Antibodies for the treatment of brain metastases, a dream or a reality?

pha maceu ics Re iew An ibodies o he T ea men o B ain Me as ases, a D eam o a Reali y? Ma co Ca aco, Diana Gaspa , Miguel ARB Cas anho * and Ve a Ne es * Ins i u o de Medicina Molecula , Faculdade de Medicina, Uni e sidade de Lisboa, A . P o . Egas Moniz, 1649-028 Lisboa, Po ugal *Co espondence: [email p o ec ed] (M.A.R.B.C.); [email p o ec ed]a.p (V.N.) Recei ed: 19 No embe 2019; Accep ed: 28 Decembe 2019; Published: 13 Janua y 2020   Abs ac : The incidence o b ain me as ases (BM) in cance pa ien s is inc easing. A e diagnosis, o e all su i al (OS) is poo , elici ed by he lack o an e ec i e ea men . Monoclonal an ibody (mAb)-based he apy has achie ed ema kable success in ea ing bo h hema ologic and non-cen al-ne ous sys em (CNS) umo s due o hei inhe en a ge ing speci ici y. Howe e , he use o mAbs in he ea men o CNS umo s is es ic ed by he blood–b ain ba ie (BBB) ha hinde s he deli e y o ei he small-molecules d ugs (sMDs) o he apeu ic p o eins (TPs). To o e come his limi a ion, ac i e esea ch is ocused on he de elopmen o s a egies o deli e TPs and inc ease hei concen a ion in he b ain. Ye , hei molecula weigh and hyd ophilic na u e u n his ask in o a challenge. The use o BBB pep ide shu les is an elegan s a egy. They explo e ei he ecep o -media ed anscy osis (RMT) o adso p i e-media ed anscy osis (AMT) o c oss he BBB. The la e is p e e able since i a oids enzyma ic deg ada ion, ecep o sa u a ion, and compe i ion wi h na u al ecep o subs a es, which educes ad e se e en s. The e o e, he combina ion o mAbs p ope ies (e.g., selec i i y and long hal -li e) wi h BBB pep ide shu les (e.g., BBB ansloca ion and deli e y in o he b ain) u ns he he apeu ic conjuga e in a alid app oach o sa ely o e come he BBB and e icien ly elimina e me as a ic b ain cells. Keywo ds: adso p i e-media ed anscy osis; an ibody agmen s; blood–b ain ba ie ; b ain me as ases; monoclonal an ibodies; pep ide shu les 1. B ain Me as ases B ain me as ases (BM) accoun o signi ican mo bidi y and mo ali y. The exac incidence is unknown [ 1 , 2 ]. Based on a ious s udies, in es iga o s es ima e ha BM occu s in 10%–20% o adul pa ien s wi h cance [ 3 ]. Ne e heless, he incidence migh be highe , and i is inc easing due o p olonged li e expec ancy, inc eased esis ance o cance he apies, and imp o ed imaging echniques. In addi ion, he inc eased pa ien su i al by ea ing p ima y umo s may inc ease he numbe o pa ien s ha will de elop mo e agg essi e BM, o ha a e esis an o he apy. Among he di e en cance ypes, lung cance (19.9%), b eas cance (15.2%), and melanoma (6.9%) a e he mos common p ima y umo s de eloping BM [ 4 ]. A e diagnosis, o e all su i al (OS) is poo . Howe e , ea ly diagnosis, imp o ed sys emic he apies, and mul imodali y ea men s ha e signi ican ly inc eased pa ien s’ su i al [5]. 1.1. BM Pa hophysiology The pa hophysiology o BM is complex and in ol es a mul i-s ep p ocess cons i u ed o wo majo s ages (Figu e 1) [ 6 ]. The i s s age is umo mig a ion, which includes (i) me as a ic clone p og ession, due o umo cells’ abili y o deg ade ex acellula ma ix (ECM); (ii) in a asa ion ( ansendo helial mig a ion o cance cells in o essels); (iii) dissemina ion (sp ead o umo cells ia bloods eam); (i ) Pha maceu ics 2020,12, 62; doi:10.3390/pha maceu ics12010062 www.mdpi.com/jou nal/pha maceu ics Pha maceu ics 2020,12, 62 2 o 22 ex a asa ion ( ansendo helial mig a ion o cance cells in o issues). The second s age co esponds o umo coloniza ion. Pha maceu ics 2020, 12, x FOR PEER REVIEW 2 o 25 bloods eam); (i ) ex a asa ion ( ansendo helial mig a ion o cance cells in o issues). The second s age co esponds o umo coloniza ion. Figu e 1. S eps in he o ma ion o b ain me as ases (BM). Me as ases o ma ion begins in he mic oen i onmen o he p ima y umo wi h 1. me as a ic clones de eloping, deg ading he ex acellula ma ix (ECM), and su e ing an epi helial–mesenchymal ansi ion (EMT) o u he de ach om he connec i e issue. 2. Subsequen ly, umo cells in ade and en e he ci cula ion (in a a ion). 3. The dissemina ion wi hin he ascula sys em d i es umo cells o dis an si es, like he b ain. 4. Then, hey ex a asa e ac oss he blood–b ain ba ie (BBB) and en e he b ain pa enchyma due o he elease o p o eoly ic enzymes and cellula in e ac ions. 5. Once inside he b ain, cance cells colonize he issue and de elop seconda y umo s. The cells p esen ed in he p ima y umo a e he e ogeneous. Among o he s, he umo mic oen i onmen is composed o cance s em cells (CSCs), pa ially di e en ia ed p ogeni o cells, and ully di e en ia ed end-s age cells [6]. Recen indings a ibu e o CSCs he p ima y esponsibili y o enhanced malignancy since hey can comple e he wo s ages o me as ases o ma ion (Figu e 1) [7]. Howe e , du ing cance p og ession, o he cells unde go an epi helial– mesenchymal ansi ion (EMT), changing hei plas ici y by mo phological and pheno ypical con e sions [8,9]. EMT enables non-CSCs o esemble a CSC s a e. Thus, hey acqui e he abili y o in ade and colonize dis an si es, c ea ing seconda y niches ha may p og ess o a seconda y umo [10]. The e o e, in he end, wi hin he umo mic oen i onmen , all cells a e malignan . Ne e heless, he de elopmen o dis al me as ases only occu s in <0.1% o dissemina ed cance cells. Thus, al hough he o ma ion o me as ases ep esen s a majo h ea , i is conside ed highly ine icien [8,11]. 1.2. BBB Physiology BBB is a complex sys em composed o a s uc u ally dis inc and con inuous endo helial cell laye sepa a ing wo b ain compa men s, namely, he blood and ex acellula luid. I s componen s include an endo helial cell laye , adjoined by igh cell- o-cell junc ion p o eins, and pinocy ic esicles [12]. All oge he , hey con ibu e o he selec i e pe meabili y o he ba ie , allowing b ain homeos asis. The BBB is also dynamic. I esponds o egula o y signals om bo h he blood and he b ain [13], being he main po al in o he b ain o gaseous molecules, such as O 2 and CO 2 , ions, nu ien s, ho mones, and wa e (Figu e 2). Hyd ophobic compounds (<500 Da) di use ac oss he endo helium memb ane. Ca ie -media ed anspo (CMT) is esponsible o he anspo o glucose Figu e 1. S eps in he o ma ion o b ain me as ases (BM). Me as ases o ma ion begins in he mic oen i onmen o he p ima y umo wi h 1. me as a ic clones de eloping, deg ading he ex acellula ma ix (ECM), and su e ing an epi helial–mesenchymal ansi ion (EMT) o u he de ach om he connec i e issue. 2. Subsequen ly, umo cells in ade and en e he ci cula ion (in a a ion). 3. The dissemina ion wi hin he ascula sys em d i es umo cells o dis an si es, like he b ain. 4. Then, hey ex a asa e ac oss he blood–b ain ba ie (BBB) and en e he b ain pa enchyma due o he elease o p o eoly ic enzymes and cellula in e ac ions. 5. Once inside he b ain, cance cells colonize he issue and de elop seconda y umo s. The cells p esen ed in he p ima y umo a e he e ogeneous. Among o he s, he umo mic oen i onmen is composed o cance s em cells (CSCs), pa ially di e en ia ed p ogeni o cells, and ully di e en ia ed end-s age cells [ 6 ]. Recen indings a ibu e o CSCs he p ima y esponsibili y o enhanced malignancy since hey can comple e he wo s ages o me as ases o ma ion (Figu e 1) [ 7 ]. Howe e , du ing cance p og ession, o he cells unde go an epi helial–mesenchymal ansi ion (EMT), changing hei plas ici y by mo phological and pheno ypical con e sions [ 8 , 9 ]. EMT enables non-CSCs o esemble a CSC s a e. Thus, hey acqui e he abili y o in ade and colonize dis an si es, c ea ing seconda y niches ha may p og ess o a seconda y umo [ 10 ]. The e o e, in he end, wi hin he umo mic oen i onmen , all cells a e malignan . Ne e heless, he de elopmen o dis al me as ases only occu s in <0.1% o dissemina ed cance cells. Thus, al hough he o ma ion o me as ases ep esen s a majo h ea , i is conside ed highly ine icien [8,11]. 1.2. BBB Physiology BBB is a complex sys em composed o a s uc u ally dis inc and con inuous endo helial cell laye sepa a ing wo b ain compa men s, namely, he blood and ex acellula luid. I s componen s include an endo helial cell laye , adjoined by igh cell- o-cell junc ion p o eins, and pinocy ic esicles [ 12 ]. All oge he , hey con ibu e o he selec i e pe meabili y o he ba ie , allowing b ain homeos asis. The BBB is also dynamic. I esponds o egula o y signals om bo h he blood and he b ain [ 13 ], being he main po al in o he b ain o gaseous molecules, such as O 2 and CO 2 , ions, nu ien s, ho mones, and wa e (Figu e 2). Hyd ophobic compounds (<500 Da) di use ac oss he endo helium memb ane. Pha maceu ics 2020,12, 62 3 o 22 Ca ie -media ed anspo (CMT) is esponsible o he anspo o glucose and amino acid esidues. While wa e -soluble molecules (e.g., ions) c oss he BBB h ough ion channels. On he o he hand, mac omolecules (p o eins and pep ides) anspo ely on endocy ic esicles, which in ol e ei he ecep o -media ed anspo (RMT) o adso p i e-media ed anspo (AMT) [14,15]. Pha maceu ics 2020, 12, x FOR PEER REVIEW 3 o 25 and amino acid esidues. While wa e -soluble molecules (e.g., ions) c oss he BBB h ough ion channels. On he o he hand, mac omolecules (p o eins and pep ides) anspo ely on endocy ic esicles, which in ol e ei he ecep o -media ed anspo (RMT) o adso p i e-media ed anspo (AMT) [14,15]. Figu e 2. Pa hways ac oss he blood–b ain ba ie (BBB). Rep esen a ion o he BBB o med by he endo helial cells and hei in e ac ion wi h as ocy es. Di e en ansloca ion ou es a e p esen ed. (a) Tigh junc ions usually es ic he pene a ion o wa e -soluble compounds. (b) The la ge su ace a ea o he lipid memb anes o he endo helium o e s an e icien di use ou e o lipid-soluble agen s. (c) Se e al anspo p o eins (ca ie s) a e p esen in he endo helium o glucose (Gluc-1), amino acids, nucleosides, and o he subs ances. (d) La ge molecules such as an ibodies, lipop o eins, p o eins, and pep ides can only ans e se he BBB by ecep o -media ed anspo (RMT). (e) The anspo o na i e plasma p o eins o pep ides is limi ed, bu ca ioniza ion can inc ease hei up ake by adso p i e-media ed anspo (AMT). Ne e heless, he BBB in e ac s wi h he me as a ic cells in an uniden i ied way. The BBB is hypo hesized o c ea e a unique b ain mic oen i onmen and o in luence me as a ic coloniza ion [16]. The inc eased pe meabili y o umo -associa ed endo helial cells, due o umo pene a ion in o he b ain, pe mi s leakage o p o eins and wa e in o b ain pa enchyma. The mechanism desc ibed is esponsible o he edema o en associa ed wi h BM [17]. Mic oglia and mac ophages in luence umo p oli e a ion and in asion by sec e ing mul iple cy okines, g ow h ac o s, enzymes, and eac i e oxygen species (ROS). O he immune cells may also pa icipa e in he BBB ansloca ion. Howe e , he exac mechanisms a e deba able [18–21]. The BBB s uc u e may be a ec ed momen a ily du ing cance cells’ in asion; howe e , in o he non-cance - ela ed cen al-ne ous sys em (CNS) pa hologies, only in ad anced disease s ages, he dys unc ion is usually signi ican . 1.3. BM T ea men Majo de elopmen s ha e been made in unde s anding b ain unc ion, me as ases p og ession, and he de elopmen o medical echnologies. Howe e , in many cases, he majo d awback in BM Figu e 2. Pa hways ac oss he blood–b ain ba ie (BBB). Rep esen a ion o he BBB o med by he endo helial cells and hei in e ac ion wi h as ocy es. Di e en ansloca ion ou es a e p esen ed. ( a ) Tigh junc ions usually es ic he pene a ion o wa e -soluble compounds. ( b ) The la ge su ace a ea o he lipid memb anes o he endo helium o e s an e icien di use ou e o lipid-soluble agen s. ( c ) Se e al anspo p o eins (ca ie s) a e p esen in he endo helium o glucose (Gluc-1), amino acids, nucleosides, and o he subs ances. ( d ) La ge molecules such as an ibodies, lipop o eins, p o eins, and pep ides can only ans e se he BBB by ecep o -media ed anspo (RMT). ( e ) The anspo o na i e plasma p o eins o pep ides is limi ed, bu ca ioniza ion can inc ease hei up ake by adso p i e-media ed anspo (AMT). Ne e heless, he BBB in e ac s wi h he me as a ic cells in an uniden i ied way. The BBB is hypo hesized o c ea e a unique b ain mic oen i onmen and o in luence me as a ic coloniza ion [ 16 ]. The inc eased pe meabili y o umo -associa ed endo helial cells, due o umo pene a ion in o he b ain, pe mi s leakage o p o eins and wa e in o b ain pa enchyma. The mechanism desc ibed is esponsible o he edema o en associa ed wi h BM [ 17 ]. Mic oglia and mac ophages in luence umo p oli e a ion and in asion by sec e ing mul iple cy okines, g ow h ac o s, enzymes, and eac i e oxygen species (ROS). O he immune cells may also pa icipa e in he BBB ansloca ion. Howe e , he exac mechanisms a e deba able [ 18 – 21 ]. The BBB s uc u e may be a ec ed momen a ily du ing cance cells’ in asion; howe e , in o he non-cance - ela ed cen al-ne ous sys em (CNS) pa hologies, only in ad anced disease s ages, he dys unc ion is usually signi ican . Pha maceu ics 2020,12, 62 4 o 22 1.3. BM T ea men Majo de elopmen s ha e been made in unde s anding b ain unc ion, me as ases p og ession, and he de elopmen o medical echnologies. Howe e , in many cases, he majo d awback in BM ea men is he ine icien d ug deli e y in o he b ain [ 22 , 23 ]. The BBB emains he mos signi ican obs acle o he e icien deli e y o small-molecule d ugs (sMDs) and he apeu ic p o eins (TPs) [ 24 ]. In addi ion, some au ho s also a ibu ed o he he apeu ic esis ance o me as a ic cells he esponsi i y o he apy ine iciency. Acco ding o hem, du ing cance p og ession, some su i al pa hways, such as he PI3K/AKT/mTOR a e ac i a ed in speci ic cells, which con ibu es o he poo esponse o me as a ic cells [25,26]. In he end, bo h mechanisms migh be con ibu ing o he apeu ic ailu e. The i s -line app oach o ea BM includes su ge y, s e eo ac ic adiosu ge y (SRS), and whole-b ain adia ion he apy (WBRT) [ 27 – 29 ]. Howe e , bo h sys emic and in ac anial disease con ol a e also possible wi h he imp o ed sys emic he apies ha ha e begun o o e g ea e po en ial o speci ic cance ypes and geno ypes. Thus, he managemen o BM has become inc easingly indi idualized [ 1 ]. Depending on he his ology and sys emic disease s a us, physicians may conside all he a ailable he apies. Fo ins ance, ecommenda ions sugges be e disease managemen by using a mul idisciplina y modali y in pa ien s wi h BM om b eas cance , melanoma, and speci ic geno ypes o non-small cell lung cance (NSCLC) (e.g., epide mal g ow h ac o ecep o (EGFR) gene mu a ions, ansloca ions in he anaplas ic lymphoma kinase (ALK) gene). Whene e possible, pa ien s may en oll in clinical ials o a no el o exis ing he apy. S ill, gi en he pauci y o e ec i e ea men op ions, BM elimina ion ep esen s an unme clinical need [30]. 2. S a egies o O e come he BBB The BBB es ic s he deli e y o he apeu ics o he b ain. O e all, 98% o sMDs and p obably all TPs canno c oss he ba ie by ee di usion [ 31 – 33 ]. In he las decade, in ense in es iga ion allowed he disco e y o new s a egies o inc ease b ain pene a ion o exis ing he apeu ics (in asi e, pha macological, and physiological) [ 34 – 36 ]. Ideally, he ansloca ion should no comp omise he BBB in eg i y. Howe e , some o he cu en s a egies do no mee his c i e ion, namely, he in asi e and pha macological app oaches. 2.1. In asi e App oach This s a egy allows d ugs o low di ec ly om he sys emic ci cula ion in o he b ain by BBB dis up ion using di e en me hodologies. The mos impo an a e: (1) osmo ic dis up ion, due o he adminis a ion o hype onic solu ions (e.g., manni ol) causing cells sh inking based on cell dehyd a ion [ 37 ]; (2) ul asound me hods, which ely on ansc anial deli e y o low- equency ul asound wa es esul ing in he opening o igh junc ions [ 38 ]; and (3) pha macological agen s, such as b adykinin-like compounds (e.g., his amine, b adykinin) ha dis up igh junc ions by s imula ing B 2 ecep o s p esen ed in endo helial cells and ansien ly inc easing cy osolic Ca 2+ [ 39 ]. The cos s, anes he ic adminis a ion, and hospi aliza ion a e signi ican d awbacks o all hese app oaches. Also, he dis up ion o he BBB may inc ease umo dissemina ion, as well as i e e sible neu opa hological changes due o he en y o unwan ed subs ances [34]. 2.2. Pha macological App oach The pha macological app oach elies on he obse a ion ha some molecules eely en e he b ain owing o hei molecula weigh (<500 Da), cha ge (low hyd ogen bonding capabili ies), and lipophilici y [ 40 ]. Thus, esea che s s a ed modi ying, h ough medicinal chemis y, molecules ha a e ac i e agains CNS diseases o BM o enable hem o ge in o he b ain [ 31 ]. Al hough i has eno mous po en ial, he modi ica ions may esul in loss o pha macological ac i i y. In addi ion, he new molecule may become a subs a e o he e lux pumps by inc easing d ugs’ lipophilici y, which dec eases b ain accumula ion [34]. Pha maceu ics 2020,12, 62 5 o 22 2.3. Physiological App oach This na u al s a egy exploi s he a ious anspo e s and ecep o s exp essed a he BBB, as well as he physiological p ope ies o he BBB (e.g., cha ge and lipid composi ion) (Figu e 2) [ 41 – 43 ]. These ansloca ion mechanisms a e undamen al o he up ake o essen ial subs ances o main ain b ain homeos asis. They can be classi ied in o: (1) CMT, which a e esponsible o he c oss o glucose (glucose anspo e —GLUT1), amino acids (la ge neu al amino acid anspo e —LAT1, and ca ionic amino acid anspo e —CAT1), and nucleosides (nucleobase anspo e —NBT); (2) RMT, undamen al o la ge molecules ansloca ion, such as ans e in ( ans e in ecep o —T R), insulin (insulin ecep o —IR), low-densi y lipop o ein (lipop o ein ecep o -media ed p o ein—LRP), lep in (lep in ecep o —LEPR), and agmen c ys allizable (Fc) agmen o immunoglobulin G (IgG) (Fc agmen o IgG ecep o anspo e α —FCGRT); and inally, (3) AMT ha d i es albumin and o he plasma p o eins o b ain [44]. CMT is an in e es ing anspo e due o he easy coupling o endogenous subs a es o sMDs [ 45 ]. Besides, i is also possible o pe o m di ec modi ica ion o sMDs o esemble CMT na u al subs a es. The changes allow d ugs o be ecognized and anspo ed ac oss he BBB [ 46 ]. Ne e heless, he molecules gene a ed: (1) mus mimic ha o he endogenous CMT subs a e; (2) should no a ec CMT physiological unc ion; and (3) mus main ain i s pha macological ac i i y. So a , a ge ing nanoca ie s o CMTs ha e been he bes example o he s a egy’s success. Howe e , he applica ion o his app oach was only possible o small molecules, as e ised in Wi e al. [47]. Ano he p omising s a egy o de elop molecules ha can e icien ly c oss he BBB is he RMT. These molecules a e known as T ojan Ho ses and can be ei he pep ides o an ibodies [ 48 ]. T R and IR a e he mos impo an BBB ecep o s explo ed by esea che s. Pa d idge e al. ha e ex ensi ely documen ed he use o an ibodies a ge ing hese ecep o s [ 49 – 51 ]. The in i o s udies demons a ed an accumula ion o di e en an i-T R monoclonal an ibodies (mAbs) in he b ain issue and a dis inc biodis ibu ion. The high a ini y o an ibodies owa ds hese ecep o s is, howe e , a limi a ion since esul s in weak ecep o dissocia ion. Consequen ly, he high-a ini y an ibodies ollow he lysosomes pa hway du ing in acellula a icking leading o i s deg ada ion [52]. Yu e al. elegan ly sol ed he p oblem by educing he a ini y o an i-T R mAbs [ 53 ]. Nex , he g oup de eloped a bispeci ic he apeu ic an ibody wi h a low a ini y o T R and a high a ini y o he enzyme β -sec e ase (BACE1), an Alzheime ’s disease d ug a ge . Rele an esul s we e ob ained om he e alua ion o he bispeci ic an ibody e icacy in non-human p ima es. The b ain accumula ion was signi ican ly highe han con ol, and he amyloid β -pep ide p esence in he b ain and se um educed conside ably [ 54 ]. Simila ly o T R, exci ing s udies a ge ing IR ha e been de eloped. Pa d idge e al. ha e shown a o al o 4% b ain up ake 3 h a e in a enous adminis a ion in Rhesus monkeys. In he ea men o Pa kinson’s, s oke, me ach oma ic leukodys ophy, and San ilippo ype A synd ome, some he apeu ic d ugs ha e been linked o he mAb and success ully ansloca ed ac oss he BBB [49,55]. Ano he in e es ing s a egy o deli e d ugs in o he b ain exploi ing RMT is he use o nanopa icles (NPs) coupled wi h mAbs o pep ides ha ecognize hese ecep o s [ 43 , 56 , 57 ]. NPs a e colloidal ca ie s o na u al o syn he ic o igin wi h a size a ying om 1 o 1000 nm. They a e a ascina ing sys em due o hei modula ing capaci y conce ning shape, size, hyd ophobici y, coa ing, chemis y, and su ace cha ge [ 58 ]. In addi ion, hey also ha e a high capaci y o d ug payload, he ela i ely ew mAbs o pep ides o achie e high le els o d ug a ge ing, p o ec ion o he encapsula ed d ug, and he abili y o p o ide a con olled elease o he d ug [59,60]. Al hough he conside able achie emen s accomplished, he d awback o hese RMT sys ems is ela ed o he compe i ion wi h na u al subs a es, which may a ec b ain homeos asis; and may esul in ecep o s’ sa u a ion due o he high a ini y o an ibodies [ 34 , 61 , 62 ]. To o e come hese limi a ions, ecen ly, mo e a en ion has been gi en o AMT. The concep o AMT h ough he BBB began wi h he obse a ion ha polyca ionic p o eins’ b ain up ake did no in ol e binding o he endo helial cell su ace [ 63 ]. Elec os a ic in e ac ion be ween posi i ely cha ged subs ances and Pha maceu ics 2020,12, 62 6 o 22 nega i ely cha ged BBB d i es he ansloca ion. The esicles c ea ed allow BBB c oss and, consequen ly, b ain accumula ion [ 64 ]. Lack o selec i i y o hese sys ems and possible BBB dis up ion we e he majo conce ns highligh ed by esea che s. Howe e , he ecen p oo -o -concep gi en by he use o cell-pene a ing pep ides (CPPs) in BBB ansloca ion (BBB pep ide-shu le) has launched a new in e es in his s a egy. These pep ides ha e demons a ed a na u al selec i i y owa ds nega i ely cha ged memb anes and he abili y o ansloca e la ge ca goes wi hou BBB damage bo h in i o and in i o models [ 65 – 67 ]. The e o e, he op imiza ion o BBB pep ide shu les based-sys ems in he deli e y o sMDs and TPs, using AMT, will be an a ea o in ense in es iga ion du ing he nex decade. 3. The apeu ic An ibodies o BM Elimina ion TPs a e he s anda d o ca e in a numbe o he apeu ic a eas [ 68 ]. They a e p o ein manu ac u ed o biopha maceu ical use and include, o ins ance, mAbs, pep ides, g ow h ac o s, cy okines, and enzymes [ 69 ]. Thei p oduc ion is ela i ely easy and elies mos ly on ei he simple pu i ica ion o ecombinan DNA echnology. Th oughou he ollowing sec ions, he desc ip ion o an ibodies’ ac i i y and hei he apeu ic alue only conce n human an ibodies. The ac i i y o an ibodies is species dependen . Thus, some ea u es p esen ed migh no be accu a e o non-human an ibodies. 3.1. Monoclonal An ibodies mAbs ep esen he as es g owing class o TPs. Cu en ly, o e 50 he apeu ic an ibodies a e on he ma ke [ 70 ]. They a e complex molecules consis ing o homodime s o a iable and cons an egions (Figu e 3) [ 71 ]. The o me has an igen speci ici y owing o he p esence o complemen a y de e mining egions (CDRs). On he o he hand, he Fc domain is esponsible o he long hal -li e o an ibodies, due o an ibody ecycling a e in e ac ion o he neona al Fc ecep o (FcRn) [ 72 ]; and immune ac i a ion (complemen -dependen cy o oxici y—CDC; and an ibody-dependen cellula cy o oxici y—ADCC) by engaging Fc γ ecep o s (Fc γ Rs) on immune cells (e.g., neu ophils, na u al kille cells, monocy es) [ 73 ]. High he apeu ic ole abili y and low isk- o-bene i a ios a o he use o he apeu ic an ibodies. Thus, hei exquisi e speci ici y, high binding a ini y, long hal -li e, low oxici y, and e sa ili y a e cha ac e is ics ha con ibu ed o an ibodies’ success [ 74 , 75 ]. Addi ionally, he low numbe o d ug–d ug in e ac ions be ween mAbs and sMDs inc eased hei combina ion in many he apeu ic egimens [70]. The mechanism o ac ion o mAbs di e s depending on he molecule enginee ed (Figu e 3). They can a ge soluble media o s (e.g., cy okines) o inhibi hei binding o ecep o s and, consequen ly, inhibi signaling; o hey can a ge memb ane ecep o s ei he inducing o an agonizing signaling (e.g., p og ammed-cell dea h ligan -1—PD-L1; o human epide mal ecep o -2—HER2, espec i ely) [ 76 ]. In addi ion, he p esence o he Fc domain allows immune s imula ion (CDC and/o ADCC). CDC is ela ed o complemen ac i a ion. Complemen is one o he i s media o s o he immune esponse o pa hogens and cells. A e binding, an ibodies ac i a e he classical complemen cascade. Thus, eleasing cy okines (e.g., anaphyla oxins and opsonins) and o ming he memb ane a ack complex (MAC), which lead o cell lysis and phagocy osis [ 77 ]. On he o he hand, ADCC occu ed due o he in e ac ion o he Fc domain wi h Fc γ Rs on e ec o immune cells (e.g., neu ophils—Fc γ RI, na u al kille cells—Fc γ IIIA; o monocy es—Fc γ IIIB). A e ecogni ion o an an ibody-coa ed a ge cell, e ec o cells engage he elease o g anzymes and pe o ins [ 78 ]. The consequence is cell dea h. The magni ude o he s imula ion o ei he CDC o ADCC depends on he IgG subse (IgG 1–4). Fo ins ance, IgG2 and IgG4 do no ac i a e bo h mechanisms. The e o e, hey a e designed p ima ily o signaling blockage. Opposi ely, IgG1 and IgG3 s ongly ac i a e bo h CDC and ADCC. Owing o i s sho hal -li e due o a low FcRn a ini y, IgG3 does no ha e he he apeu ic alue o o he IgG subse s [79]. Pha maceu ics 2020,12, 62 7 o 22 Pha maceu ics 2020, 12, x FOR PEER REVIEW 7 o 25 Figu e 3. Main unc ions o he apeu ic monoclonal an ibodies (mAbs). mAbs ha e wo an igen- binding agmen s (Fabs) and one cons an agmen c ys allizable (Fc). The a iable domain o he Fab con e s speci ici y and binding a ini y o ei he memb ane ecep o s o soluble an igens. The Fc domain binds neona al Fc ecep o (FcRn), p olonging he hal -li e o mAbs; and connec s immunoglobulin G (IgG) an ibodies o immune e ec o mechanisms (an ibody-dependen cell cy o oxici y—ADCC; and complemen -dependen cy o oxici y—CDC) by engaging Fcγ ecep o s (FcγR) on immune cells, p omo ing cell lysis. 3.2. The apeu ic Value The i s mAb app o ed was mu omonab-CD3 in he p e en ion o ansplan ejec ion. E e since, mAbs ha e been in oduced in a numbe o he apeu ic egimens in a wide ange o condi ions, such as o gan ansplan a ion (e.g., basiliximab and bela acep ), in lamma o y diseases (e.g., adalimumab and ocilizumab), and cance (e.g., as uzumab and ce uximab) [70]. The use o an ibodies is inc easing and imp o ed mAb-based s a egies will appea on he ma ke in esponse o cu en he apeu ic challenges (Figu e 4). In pa icula , an ibody esea ch ocused on he de elopmen o an ibody agmen s (e.g., single-chain F —scF , single-domain an ibody—sdAb, an igen-binding agmen s—Fab); an ibody–d ug conjuga es (ADC) (e.g., as uzumab em ansine); usion p o eins (e.g., e ane cep ); and in abodies [80–82]. Al hough physicians use mAbs in a a ie y o condi ions, hei applicabili y in he ea men o CNS diseases and BM emains challenging. Ne e heless, he e a e some mAb-based sys ems al eady app o ed (Table 1) o in in es iga ion (Table 2). Figu e 3. Main unc ionso he apeu icmonoclonalan ibodies(mAbs). mAbsha e wo an igen-binding agmen s (Fabs) and one cons an agmen c ys allizable (Fc). The a iable domain o he Fab con e s speci ici y and binding a ini y o ei he memb ane ecep o s o soluble an igens. The Fc domain binds neona al Fc ecep o (FcRn), p olonging he hal -li e o mAbs; and connec s immunoglobulin G (IgG) an ibodies o immune e ec o mechanisms (an ibody-dependen cell cy o oxici y—ADCC; and complemen -dependen cy o oxici y—CDC) by engaging Fc γ ecep o s (Fc γ R) on immune cells, p omo ing cell lysis. 3.2. The apeu ic Value The i s mAb app o ed was mu omonab-CD3 in he p e en ion o ansplan ejec ion. E e since, mAbs ha e been in oduced in a numbe o he apeu ic egimens in a wide ange o condi ions, such as o gan ansplan a ion (e.g., basiliximab and bela acep ), in lamma o y diseases (e.g., adalimumab and ocilizumab), and cance (e.g., as uzumab and ce uximab) [ 70 ]. The use o an ibodies is inc easing and imp o ed mAb-based s a egies will appea on he ma ke in esponse o cu en he apeu ic challenges (Figu e 4). In pa icula , an ibody esea ch ocused on he de elopmen o an ibody agmen s (e.g., single-chain F —scF , single-domain an ibody—sdAb, an igen-binding agmen s—Fab); an ibody–d ug conjuga es (ADC) (e.g., as uzumab em ansine); usion p o eins (e.g., e ane cep ); and in abodies [ 80 – 82 ]. Al hough physicians use mAbs in a a ie y o condi ions, hei applicabili y in he ea men o CNS diseases and BM emains challenging. Ne e heless, he e a e some mAb-based sys ems al eady app o ed (Table 1) o in in es iga ion (Table 2). Pha maceu ics 2020,12, 62 8 o 22 Pha maceu ics 2020, 12, x FOR PEER REVIEW 8 o 25 Figu e 4. No el o inno a i e monoclonal an ibody (mAb) s a egies. Schema ic ep esen a ion o di e en an ibody o ma s cu en ly in esea ch. (A) An in ac IgG molecule alongside wi h a ious an ibody agmen s and hei espec i e molecula weigh . (B) An ibody-d ug conjuga es (ADC) a e usually in ac IgG molecules linked o a d ug, oxin, o pep ide o inc ease he ca go selec i i y. (C) Fusion p o eins a e biopha maceu ical molecules whe e he binding domains can be de i ed om a ecep o ex acellula domain, cy okine, enzyme, and pep ide. Depending on he IgG molecule, he Fc egion is capable o FcγR and C1q binding, po en ially enabling he usion p o ein o ini ia e an ibody-dependen cell-media ed cy o oxici y (ADCC) and complemen -dependen cy o oxici y (CDC). (D) The scheme shows an in abody made o a a iable egion o he ligh and hea y chain cons i u ing he an igen-binding domain and an in acellula loca ion domain o allow nuclea binding. 3.3. CNS Diseases Mul iple scle osis and episodic headache a e he only neu ologic pa hologies whe e mAbs ha e been adminis a ed, which s a ed wi h he app o al o na alizumab [83] and e enumab [84], espec i ely. Na alizumab is an IgG4 mAb a ge ing α4β1-in eg in ( e y la e ac i a ion an igen-4— VLA-4), which is p esen on he su ace o leukocy es. A e binding o VLA-4, he mAb inhibi s he in e ac ion be ween VLA-4 and ascula cell adhesion molecule-1 (VCAM-1). Consequen ly, educing he adhesion, a achmen , and mig a ion o leukocy es ac oss he BBB in o he CNS [85]. In a pi o al phase III ial (AFFIRM), na alizumab educed clinical elapse a one-yea by 68% and he isk o con inuous p og ession o disabili y by 42–54% o e wo yea s [86]. Ne e heless, he he apeu ic e ec obse ed occu s due o a pe iphe al ac ion, ins ead o a di ec an ibody pene a ion in o he b ain. E enumab is an IgG2, which a ge s he calci onin gene- ela ed pep ide (CGRP) ecep o [87]. The mAb compe es wi h he binding o CGRP and inhibi s i s unc ion a he CGRP ecep o . The CGRP ecep o s a e loca ed a ele an si es o mig aine pa hophysiology, such as he igeminal ganglion and he pa a en icula s uc u es. The BBB does no p o ec hese egions. Thus, e enumab also exe s ac ion a he pe iphe y and no a he b ain. In phase III STRIVE clinical ial, Figu e 4. No el o inno a i e monoclonal an ibody (mAb) s a egies. Schema ic ep esen a ion o di e en an ibody o ma s cu en ly in esea ch. ( A ) An in ac IgG molecule alongside wi h a ious an ibody agmen s and hei espec i e molecula weigh . ( B ) An ibody-d ug conjuga es (ADC) a e usually in ac IgG molecules linked o a d ug, oxin, o pep ide o inc ease he ca go selec i i y. ( C ) Fusion p o eins a e biopha maceu ical molecules whe e he binding domains can be de i ed om a ecep o ex acellula domain, cy okine, enzyme, and pep ide. Depending on he IgG molecule, he Fc egion is capable o Fc γ R and C1q binding, po en ially enabling he usion p o ein o ini ia e an ibody-dependen cell-media edcy o oxici y(ADCC) and complemen -dependen cy o oxici y (CDC). ( D ) The scheme shows an in abody made o a a iable egion o he ligh and hea y chain cons i u ing he an igen-binding domain and an in acellula loca ion domain o allow nuclea binding. 3.3. CNS Diseases Mul iple scle osis and episodic headache a e he only neu ologic pa hologies whe e mAbs ha e beenadminis a ed,whichs a edwi h heapp o alo na alizumab[ 83 ]ande enumab[ 84 ], espec i ely. Na alizumab is an IgG4 mAb a ge ing α 4 β 1-in eg in ( e y la e ac i a ion an igen-4—VLA-4), which is p esen on he su ace o leukocy es. A e binding o VLA-4, he mAb inhibi s he in e ac ion be ween VLA-4 and ascula cell adhesion molecule-1 (VCAM-1). Consequen ly, educing he adhesion, a achmen , and mig a ion o leukocy es ac oss he BBB in o he CNS [ 85 ]. In a pi o al phase III ial (AFFIRM), na alizumab educed clinical elapse a one-yea by 68% and he isk o con inuous p og ession o disabili y by 42–54% o e wo yea s [ 86 ]. Ne e heless, he he apeu ic e ec obse ed occu s due o a pe iphe al ac ion, ins ead o a di ec an ibody pene a ion in o he b ain. E enumab is an IgG2, which a ge s he calci onin gene- ela ed pep ide (CGRP) ecep o [ 87 ]. The mAb compe es wi h he binding o CGRP and inhibi s i s unc ion a he CGRP ecep o . The CGRP ecep o s a e loca ed a ele an si es o mig aine pa hophysiology, such as he igeminal ganglion and he pa a en icula s uc u es. The BBB does no p o ec hese egions. Thus, e enumab also exe s ac ion a he pe iphe y and no a he b ain. In phase III STRIVE clinical ial, e enumab was able o signi ican ly educe he Pha maceu ics 2020,12, 62 9 o 22 numbe o mig aine days pe mon h by 3.2 e sus 1.8 in he placebo g oup. E icacy was sus ained up o one yea [88]. A di e en s a egy was applied in he managemen o Alzheime ’s disease. In his case, ins ead o an ibodies ac ing a he pe iphe y, esea che s a e using mAbs and e-enginee ed an ibody agmen s a ge ing na u al b ain po als (e.g., T R and IR) [ 44 ]. Pa d idge e al. epo ed o he i s ime an an i- β -amyloid (A β ) scF used o mAbs a ge ing ei he T R o IR [ 89 ]. The b ain up ake o he molecule was o 0.88% ID/b ain. The alue is wi hin he bounda ies o he b ain up ake o o he d ugs ha a e ac i e in he b ain [ 44 , 90 , 91 ]. Howe e , he mAb demons a ed a high a ini y owa ds he ecep o . Thus, ecep o dissocia ion was a majo limi a ion. The consequence migh be an ibody deg ada ion since he molecules, ins ead o c ossing he BBB, ollow he lysosomal pa hway. Yu e al. elegan ly sol ed he p oblem by educing he a ini y o hese mAb [ 53 ]. In addi ion, he g oup u he de eloped a bispeci ic he apeu ic an ibody wi h a low a ini y o T R and a high a ini y o ano he Alzheime ’s disease d ug a ge , he BACE1 [ 54 ]. The b ain accumula ion o he molecule in non-human p ima es was signi ican ly highe han con ol, and he amyloid β -pep ide p esence in he b ain and se um educed conside ably. The d awback o hese RMT sys ems is he compe i ion wi h na u al subs a es, which may a ec b ain homeos asis; and ecep o sa u a ion due o he high a ini y o he an ibodies enginee ed [44]. 3.4. B ain Me as ases In he ea men o BM, he eali y is di e en . In he ec ui men phase o clinical ials, an ac i e exclusion o pa ien s p esen ing BM occu s [ 92 , 93 ]. The e o e, o da e, no clinical ial suppo s he use o mAbs in he managemen o BM. The lack o in o ma ion conce ning e icacy and sa e y a e he main easons. Consequen ly, he s anda d cance egimens wi h well-es ablished an ibody-based ea men s canno be applied o pa ien s wi h BM [ 94 ]. Thei use by physicians ep esen s an o -label use. Ne e heless, a class o mAbs ela ed o immuno he apy (e.g., ni olumab, pemb olizumab) is showing p omising esul s. Se e al s udies sugges hei ole in he elimina ion o me as a ic umo s, such as in he b ain. S ill, mo e da a is necessa y o app o e hese an ibodies in he ea men o me as a ic b ain cance s [ 95 ]. Ano he p omising ield is he adionuclide he apy. In he las yea s, nume ous pape s ha e been published epo ing i s success in b ain umo s and me as ases [96]. New he apeu ic a ge s in me as a ic p og ession in ei he p ima y o seconda y umo s ha e d i en in ense esea ch in o he de elopmen o mAb-based sys ems [ 97 , 98 ], as hey o e e ec i e a ge ed ea men wi h low ad e se e en s. Howe e , he lack o speci ici y and poo BBB pene a ion ende hem ine ec i e. I is he e o e impe a i e o ind s a egies ha allow an ibody ansloca ion ac oss he BBB. Fo ins ance, he use o an ibody agmen s o educe hei molecula weigh . O modi y he mAbs o con ain a ansloca ion moie y, such as a CPPs. CPPs a e e ec i e in he deli e y o la ge ca goes ac oss cell memb anes and e en ac oss he BBB (BBB pep ide shu les) [ 66 , 99 ]. Simila o he T ojan ho se app oach hey engage in e ac ion wi h BECs and BBB ansloca ion, he main ad an age being ha CPP does no equi e ecep o s in he majo i y o he cases, hus educing he oxici y o he sys em signi ican ly. Pha maceu ics 2020,12, 62 16 o 22 inc ease in cance incidence and mo ali y was he de elopmen o mo e e ec i e, umo -speci ic, and less oxic an i-cance d ugs. The use o a ge ed he apy o human cance s using mAb-based sys ems has e olu ionized cance he apy. They a e cu en ly being used as he i s choice o ea some o he mos equen me as a ic cance s, such as HER2+b eas cance s o colo ec al cance s. Mo e ecen ly, he e icacy demons a ed by an ibodies inhibi ing immune checkpoin s has ex ended hei use in o he umo ypes. In addi ion, hey ha e also been in oduced in many he apeu ic p o ocols in combina ion wi h sMDs. Fo he ea men o cance , he Food and D ug Adminis a ion (FDA) and he Eu opean Medicines Agency (EMA) ha e app o ed 32 mAbs-based sys ems. In e es ingly, be ween 2012 and 2017 he numbe has doubled. The e o e, he alue o mAbs in cance he apy is undispu able. Despi e he exci emen o mAbs-based sys ems in cance ea men , hei use in b ain cance s and BMs a e limi ed since hey a e unable o c oss he BBB. Thei molecula weigh and hyd ophilic na u e di icul b ain accumula ion. The e o e, o c ea e BM speci ic mAbs-based sys ems, hey need o be modi ied o ge ac oss he BBB. Many s a egies ha e been employed o mAbs o become a eali y in he ea men o BMs. The mos p omising uses BBB pep ide shu les conjuga ed o mAbs-based sys ems. These pep ides use endogenous ou es, such as RMT o AMT o c oss he BBB. Al hough RMT has been by a he mos exploi ed ou e, i p esen s se e al disad an ages, namely, he ecep o ’s sa u a ion and na u al ligand compe i ion. The e o e, wi h he ad en o many pep ide shu les explo ing AMT, he c ossing o he BBB wi hou in e e ing wi h b ain homeos asis has become a eali y. Consequen ly, he numbe o s udies in ol ing BBB pep ide shu les mAb-based sys ems a e inc easing in he li e a u e. In conclusion, BBB pep ide shu les mAb-based sys ems a e being designed and s udied wi h some limi a ions. Howe e , he a ac i e esul s wi hin di e en s udies alida e hei applica ion. Consequen ly, in he nea u u e, i is expec ed a signi ican inc ease in he numbe o molecules conjuga ed o BBB pep ide shu les pushing he use o an ibodies o he ea men o BMs in o a eali y. Au ho Con ibu ions: M.C., D.G., M.A.R.B.C., and V.N. con ibu ed o he s uc u ing o he p esen e iew, o he li e a u e sea ch, and o he w i ing o he manusc ip . All au ho s ha e ead and ag eed o he published e sion o he manusc ip . Funding: This esea ch was unded by he Po uguese Funding Agency, Fundaç ã o pa a a Ci ê ncia e Tecnologia, FCT IP, g an s PD/BD/128281/2017, PTDC/BBB-BQB/1693/2014 and PTDC/BBB-NAN/1578/2014. Con lic s o In e es : The au ho s decla e no con lic o in e es . Re e ences 1. Lin, X.; DeAngelis, L.M. T ea men o B ain Me as ases. J. Clin. Oncol. 2015 ,33, 3475–3484. [C ossRe ] [PubMed] 2. Cagney, D.N.; Ma in, A.M.; Ca alano, P.J.; Redig, A.J.; Lin, N.U.; Lee, E.Q.; Wen, P.Y.; Dunn, I.F.; Bi, W.L.; Weiss, S.E.; e al. Incidence and p ognosis o pa ien s wi h b ain me as ases a diagnosis o sys emic malignancy: A popula ion-based s udy. Neu o-Oncology 2017,19, 1511–1521. [C ossRe ] 3. Nayak, L.; Lee, E.Q.; Wen, P.Y. Epidemiology o B ain Me as ases. Cu . Oncol. Rep. 2012 ,14, 48–54. [C ossRe ] [PubMed] 4. Tabou e , E.; Chino , O.; Me ellus, P.; Talle , A.; Viens, P.; GonÇAl es, A. Recen T ends in Epidemiology o B ain Me as ases: An O e iew. An icance Res. 2012,32, 4655–4662. [PubMed] 5. Eichle , A.F.; Loe le , J.S. Mul idisciplina y Managemen o B ain Me as ases. Oncology 2007 ,12, 884–898. [C ossRe ] [PubMed] 6. Massagué, J.; Obenau , A.C. Me as a ic Coloniza ion. Na u e 2016,529, 298–306. [C ossRe ] 7. Ren, D.; Zhu, X.; Kong, R.; Zhao, Z.; Sheng, J.; Wang, J.; Xu, X.; Liu, J.; Cui, K.; Zhang, X.H.F.; e al. Ta ge ing B ain-Adap i e Cance S em Cells P ohibi s B ain Me as a ic Coloniza ion o T iple-Nega i e B eas Cance . Cance Res. 2018,78, 2052–2064. [C ossRe ] 8. an Zijl, F.; K upi za, G.; Mikuli s, W. Ini ial s eps o me as asis: Cell in asion and endo helial ansmig a ion. Mu a . Res. 2011,728, 23–34. [C ossRe ] Pha maceu ics 2020,12, 62 17 o 22 9. Jee an, D.S.; Coope , J.B.; B aun, A.; Mu ali, R.A.J.; Jhanwa -Uniyal, M. Molecula Pa hways Media ing Me as ases o he B ain ia Epi helial- o-Mesenchymal T ansi ion: Genes, P o eins, and Func ional Analysis. An icance Res. 2016,36, 523–532. 10. Mani, S.A.; Guo, W.; Liao, M.-J.; Ea on, E.N.; Ayyanan, A.; Zhou, A.Y.; B ooks, M.; Reinha d, F.; Zhang, C.C.; Shipi sin, M.; e al. The epi helial–mesenchymal ansi ion gene a es cells wi h p ope ies o s em cells. Cell 2008,133, 704–715. [C ossRe ] 11. Celi à -Te assa, T.; Kang, Y. Me as a ic niche unc ions and he apeu ic oppo uni ies. Na . Cell Biol. 2018 ,20, 868–877. [C ossRe ] [PubMed] 12. Se lin, Y.; Shele , I.; Knyaze , B.; F iedman, A. Ana omy and Physiology o he Blood–b ain Ba ie . Semin. Cell De . Biol. 2015,38, 2–6. [C ossRe ] [PubMed] 13. S azielle, N.; Ghe si-Egea, J.F. Physiology o Blood–B ain In e aces in Rela ion o B ain Disposi ion o Small Compounds and Mac omolecules. Mol. Pha m. 2013,10, 1473–1491. [C ossRe ] [PubMed] 14. Sha i , Y.; Jumah, F.; Coplan, L.; K osse , A.; Sha i , K.; Tubbs, R.S. Blood b ain ba ie : A e iew o i s ana omy and physiology in heal h and disease. Clin. Ana . 2018,31, 812–823. [C ossRe ] 15. Daneman, R.; P a , A. The blood–b ain ba ie . Cold Sp ing Ha b. Pe spec . Biol. 2015 ,7, a020412. [C ossRe ] 16. Weil, R.J.; Palmie i, D.C.; B onde , J.L.; S a k, A.M.; S eeg, P.S. B eas Cance Me as asis o he Cen al Ne ous Sys em. Am. J. Pa hol. 2005,167, 913–920. [C ossRe ] 17. Lesniak, M.S.; B em, H. Ta ge ed he apy o b ain umou s. Na . Re . D ug Disco . 2004 ,3, 499–508. [C ossRe ] 18. G een, C.E.; Liu, T.; Mon el, V.; Hsiao, G.; Les e , R.D.; Sub amaniam, S.; Gonias, S.L.; Klemke, R.L. Chemoa ac an Signaling be ween Tumo Cells and Mac ophages Regula es Cance Cell Mig a ion, Me as asis and Neo ascula iza ion. PLoS ONE 2009,4, e6713. [C ossRe ] 19. Gonzalez, H.; Hage ling, C.; We b, Z. Roles o he immune sys em in cance : F om umo ini ia ion o me as a ic p og ession. Genes De . 2018,32, 1267–1284. [C ossRe ] 20. You, H.; Baluszek, S.; Kaminska, B. Immune Mic oen i onmen o B ain Me as ases—A e Mic oglia and O he B ain Mac ophages Li le Helpe s? F on . Immunol. 2019,10, 1941. [C ossRe ] 21. Leibold, A.T.; Monaco, G.N.; Dey, M. The ole o he immune sys em in b ain me as asis. Cu . Neu obiol. 2019,10, 33–48. [PubMed] 22. DiLo enzo,R.; Ahluwalia,M.S.Ta ge ed he apyo b ainme as ases: La es e idence andclinicalimplica ions. The . Ad . Med. Oncol. 2017,9, 781–796. [C ossRe ] [PubMed] 23. F anchino, F.; Rud à , R.; So ie i, R. Mechanisms and The apy o Cance Me as asis o he B ain. F on . Oncol. 2018,8, 161. [C ossRe ] [PubMed] 24. Pa d idge, W.M. Blood–b ain ba ie deli e y. D ug Disco . Today 2007,12, 54–61. [C ossRe ] [PubMed] 25. Kab aji, S.; Ni, J.; Lin, N.U.; Xie, S.; Wine , E.P.; Zhao, J.J. D ug Resis ance in HER2-Posi i e B eas Cance B ain Me as ases: Blame he Ba ie o he B ain? Clin. Cance Res. O . J. Am. Assoc. Cance Res. 2018 ,24, 1795–1804. [C ossRe ] 26. Dong, R.; Ji, J.; Liu, H.; He, X. The e ol ing ole o as uzumab em ansine (T-DM1) in HER2-posi i e b eas cance wi h b ain me as ases. C i . Re . Oncol. Hema ol. 2019,143, 20–26. [C ossRe ] 27. Niede , C.; G osu, A.L.; Gaspa , L.E. S e eo ac ic adiosu ge y (SRS) o b ain me as ases: A sys ema ic e iew. Radia . Oncol. 2014,9, 155. [C ossRe ] 28. P o opapa,M.; Kouloulias, V.; Nikoloudi,S.; Papadimi iou,C.; Gogalis, G.; Zygogianni, A. F omWhole-B ain Radio he apy o Immuno he apy: A Mul idisciplina y App oach o Pa ien s wi h B ain Me as ases om NSCLC. J. Oncol. 2019,2019, 12. [C ossRe ] 29. Ulahannan, D.; Khali a, J.; Fai e-Finn, C.; Lee, S.M. Eme ging ea men pa adigms o b ain me as asis in non-small-cell lung cance : An o e iew o he cu en landscape and challenges ahead. Ann. Oncol. 2017 , 28, 2923–2931. [C ossRe ] 30. Ha des y, D.A.; Nakaji, P. The Cu en and Fu u e T ea men o B ain Me as ases. F on . Su g. 2016 ,3, 30. [C ossRe ] 31. Papademe iou, I.T.; Po e , T. P omising app oaches o ci cum en he blood–b ain ba ie : P og ess, pi alls and clinical p ospec s in b ain cance . The . Deli . 2015,6, 989–1016. [C ossRe ] [PubMed] 32. Teleanu, D.M.; Chi co , C.; G umezescu, A.M.; Volceano , A.; Teleanu, R.I. Blood–b ain Deli e y Me hods Using Nano echnology. Pha maceu ics 2018,10, 269. [C ossRe ] [PubMed] 33. Dong, X. Cu en S a egies o B ain D ug Deli e y. The anos ics 2018,8, 1481–1493. [C ossRe ] [PubMed] Pha maceu ics 2020,12, 62 18 o 22 34. Gaba hule , R. App oaches o anspo he apeu ic d ugs ac oss he blood–b ain ba ie o ea b ain diseases. Neu obiol. Dis. 2010,37, 48–57. [C ossRe ] 35. Belle a o, C.M.; Sca pa, M. Possible s a egies o c oss he blood–b ain ba ie . I al. J. Pedia ics 2018 ,44, 131. [C ossRe ] 36. Pandey, P.K.; Sha ma, A.K.; Gup a, U. Blood b ain ba ie : An o e iew on s a egies in d ug deli e y, ealis ic in i o modeling and in i o li e acking. Tissue Ba ie s 2015,4, e1129476. [C ossRe ] 37. Fo in, D.; Gend on, C.; Boud ias, M.; Ga an , M.-P. Enhanced chemo he apy deli e y by in aa e ial in usion and blood–b ain ba ie dis up ion in he ea men o ce eb al me as asis. Cance 2007 ,109, 751–760. [C ossRe ] 38. Kinoshi a, M.; McDannold, N.; Jolesz, F.A.; Hynynen, K. Ta ge ed deli e y o an ibodies h ough he blood–b ain ba ie by MRI-guided ocused ul asound. Biochem. Biophys. Res. Commun. 2006 ,340, 1085–1090. [C ossRe ] 39. Bo longan, C.V.; Eme ich, D.F. Facili a ion o d ug en y in o he CNS ia ansien pe mea ion o blood b ain ba ie : Labo a o y and p elimina y clinical e idence om b adykinin ecep o agonis , Ce epo . B ain Res. Bull. 2003,60, 297–306. [C ossRe ] 40. Lipinski, C.A.; Lomba do, F.; Dominy, B.W.; Feeney, P.J. Expe imen al and compu a ional app oaches o es ima e solubili y and pe meabili y in d ug disco e y and de elopmen se ings1PII o o iginal a icle: S0169-409X(96)00423-1. The a icle was o iginally published in Ad anced D ug Deli e y Re iews 23 (1997) 3–25.1. Ad . D ug Deli . Re . 2001,46, 3–26. [C ossRe ] 41. Tajes, M.; Ramos-Fe n á ndez, E.; Weng-Jiang, X.; Bosch-Mo a ó , M.; Gui e nau, B.; E aso-Picho , A.; Sal ado , B.; Fe n à ndez-Busque s, X.; Roque , J.; Muñoz, F.J. The blood–b ain ba ie : S uc u e, unc ion and he apeu ic app oaches o c oss i . Molec. Memb . Biol. 2014,31, 152–167. [C ossRe ] [PubMed] 42. Pa odi, A.; Rudzi´nska, M.; De ia kin, A.A.; Soond, S.M.; Baldin, A.V.; Zamya nin, A.A., J . Es ablished and Eme ging S a egies o D ug Deli e y Ac oss he Blood–b ain Ba ie in B ain Cance . Pha maceu ics 2019 , 11, 245. [C ossRe ] [PubMed] 43. Pulga , V.M. T anscy osis o C oss heBlood B ainBa ie , NewAd ancemen s andChallenges. F on . Neu osci. 2019,12, 1019. [C ossRe ] [PubMed] 44. Ne es, V.; Ai es-da-Sil a, F.; Co e-Real, S.; Cas anho, M.A.R.B. An ibody App oaches To T ea B ain Diseases. T ends Bio echnol. 2015,34, 36–48. [C ossRe ] 45. Khan, N.U.; Miao, T.; Ju, X.; Guo, Q.; Han, L. 6—Ca ie -Media ed T anspo a ion h ough BBB. In B ain Ta ge ed D ug Deli e y Sys em; Gao, H., Gao, X., Eds.; Academic P ess: New Yo k, NY, USA, 2019; pp. 129–158. [C ossRe ] 46. Pa an, B.; Dalpiaz, A.; Cilibe i, N.; Ve uani, S. P og ess in D ug Deli e y o he Cen al Ne ous Sys em by he P od ug App oach. Molecules 2008,13, 1035–1065. [C ossRe ] 47. Wi , K.A.; Gillespie, T.J.; Hube , J.D.; Egle on, R.D.; Da is, T.P. Pep ide d ug modi ica ions o enhance bioa ailabili y and blood–b ain ba ie pe meabili y. Pep ides 2001,22, 2329–2343. [C ossRe ] 48. Pa d idge, W.M. D ug anspo ac oss he blood–b ain ba ie . J. Ce eb Blood Flow. Me ab. 2012 ,32, 1959–1972. [C ossRe ] 49. Coloma, M.J.; Lee, H.J.; Ku iha a, A.; Landaw, E.M.; Boado, R.J.; Mo ison, S.L.; Pa d idge, W.M. T anspo Ac oss he P ima e Blood–b ain Ba ie o a Gene ically Enginee ed Chime ic Monoclonal An ibody o he Human Insulin Recep o . Pha m. Res. 2000,17, 266–274. [C ossRe ] 50. Pa d idge, W. Blood–b ain ba ie d ug a ge ing: The u u e o b ain d ug de elopmen . Mol. In e . 2003 , 3, 90–105. [C ossRe ] 51. Zhang, Y.; Pa d idge, W.M. Blood–b ain ba ie a ge ing o BDNF imp o es mo o unc ion in a s wi h middle ce eb al a e y occlusion. B ain Res. 2006,1111, 227–229. [C ossRe ] 52. Bien-Ly, N.; Yu, Y.J.; Bumbaca, D.; Els o , J.; Boswell, C.A.; Zhang, Y.; Luk, W.; Lu, Y.; Dennis, M.S.; Weime , R.M.; e al. T ans e in ecep o (T R) a icking de e mines b ain up ake o T R an ibody a ini y a ian s. J. Exp. Med. 2014,211, 233–244. [C ossRe ] 53. Yu, Y.J.; Zhang, Y.; Ken ick, M.; Hoy e, K.; Luk, W.; Lu, Y.; A wal, J.; Ellio , J.M.; P abhu, S.; Wa s, R.J.; e al. Boos ing B ain Up ake o a The apeu ic An ibody by Reducing I s A ini y o a T anscy osis Ta ge . Sci. T ansl. Med. 2011,3, 84 a44. [C ossRe ] [PubMed] Pha maceu ics 2020,12, 62 19 o 22 54. Yu, Y.J.; A wal, J.K.; Zhang, Y.; Tong, R.K.; Wildsmi h, K.R.; Tan, C.; Bien-Ly, N.; He som, M.; Maloney, J.A.; Meiland , W.J.; e al. The apeu ic bispeci ic an ibodies c oss he blood–b ain ba ie in nonhuman p ima es. Sci. T ansl. Med. 2014,6, 261 a154. [C ossRe ] [PubMed] 55. Boado, R.J.; Zhang, Y.; Zhang, Y.; Pa d idge, W.M. Humaniza ion o an i-human insulin ecep o an ibody o d ug a ge ing ac oss he human blood–b ain ba ie . Bio echnol. Bioeng. 2007 ,96, 381–391. [C ossRe ] [PubMed] 56. Viei a, D.B.; Gama a, L.F. Mul i unc ional Nanopa icles o Success ul Ta ge ed D ug Deli e y ac oss he Blood–b ain Ba ie , Molecula Insigh o D ug Design. In echOpen 2018. [C ossRe ] 57. Tang, W.; Fan, W.; Lau, J.; Deng, L.; Shen, Z.; Chen, X. Eme ging blood–b ain-ba ie -c ossing nano echnology o b ain cance he anos ics. Chem. Soc. Re . 2019,48, 2967–3014. [C ossRe ] 58. Sa ai a, C.; P aça, C.; Fe ei a, R.; San os, T.; Fe ei a, L.; Be na dino, L. Nanopa icle-media ed b ain d ug deli e y: O e coming blood–b ain ba ie o ea neu odegene a i e diseases. J. Con ol. Release 2016,235, 34–47. [C ossRe ] 59. Lou ei o, J.A.; Gomes, B.; Coelho, M.A.N.; Ca mo Pe ei a, M.d.; Rocha, S. Ta ge ing nanopa icles ac oss he blood–b ain ba ie wi h monoclonal an ibodies. Nanomedicine 2014,9, 709–722. [C ossRe ] 60. Fu ado, D.; Bjö nmalm, M.; Ay on, S.; Bush, A.I.; Kempe, K.; Ca uso, F. O e coming he Blood–B ain Ba ie : The Role o Nanoma e ials in T ea ing Neu ological Diseases. Ad . Ma e . 2018,30, 1801362. [C ossRe ] 61. Abdul Razzak, R.; Flo ence, G.J.; Gunn-Moo e, F.J. App oaches o CNS D ug Deli e y wi h a Focus on T anspo e -Media ed T anscy osis. In . J. Mol. Sci. 2019,20, 3108. [C ossRe ] 62. Mäge , I.; Meye , A.H.; Li, J.; Len e , M.; Hildeb and , T.; Lepa c, G.; Wood, M.J.A. Ta ge ing blood–b ain-ba ie anscy osis—Pe spec i es o d ug deli e y. Neu opha macology 2017 ,120, 4–7. [C ossRe ] [PubMed] 63. Bickel, U. An ibody deli e y h ough he blood–b ain ba ie . Ad . D ug Deli . Re . 1995 ,15, 53–72. [C ossRe ] 64. Kumagai, A.; Eisenbe g, J.; Pa d idge, W. Adso p i e-media ed anscy osis o ca ionized albumin and a be a-endo phin-ca ionized albumin chime ic pep ide by isola ed b ain capilla ies. Model sys em o blood–b ain ba ie anspo . J. Biol. Chem. 1987,262, 15414–15419. 65. He é , F.; Ghinea, N.; Sche mann, J.-M. CNS Deli e y Via Adso p i e T anscy osis. AAPS J. 2008 ,10, 455–472. [C ossRe ] 66. Olle -Sal ia, B.; Sanchez-Na a o, M.; Gi al , E.; Teixido, M. Blood–b ain ba ie shu le pep ides: An eme ging pa adigm o b ain deli e y. Chem. Soc. Re . 2016,45, 4690–4707. [C ossRe ] 67. McCully, M.; Sanchez-Na a o, M.; Teixido, M.; Gi al , E. Pep ide Media ed B ain Deli e y o Nano- and Submic opa icles: A Syne gis ic App oach. Cu . Pha m. Des. 2018,24, 1366–1376. [C ossRe ] 68. Lagass é , H.A.D.; Alexaki, A.; Simhad i, V.L.; Ka agi i, N.H.; Jankowski, W.; Sauna, Z.E.; Kimchi-Sa a y, C. Recen ad ances in ( he apeu ic p o ein) d ug de elopmen . F1000Resea ch 2017,6, 113. [C ossRe ] 69. Lee, J.I.; Zhang, L.; Men, A.Y.; Kenna, L.A.; Huang, S.M. CYP-Media ed The apeu ic P o ein-D ug In e ac ions. Clin. Pha m. 2010,49, 295–310. [C ossRe ] 70. Ca aco, M.; Goncal es, J. In e ac ions be ween he apeu ic p o eins and small molecules: The sha ed ole o pe pe a o s and ic ims. Clin. Pha m. The . 2016,102, 649–661. [C ossRe ] 71. Moo hy, B.S.; Xie, B.; Moussa, E.M.; Iye , L.K.; Chand asekha , S.; Panchal, J.P.; Topp, E.M. S uc u e o Monoclonal An ibodies. In Biobe e s: P o ein Enginee ing o App oach he Cu a i e; Rosenbe g, A., Demeule, B., Eds.; Sp inge : New Yo k, NY, USA, 2015; pp. 81–89. [C ossRe ] 72. Roopenian, D.C.; Akilesh, S. FcRn: The neona al Fc ecep o comes o age. Na . Re . Immunol. 2007 ,7, 715–725. [C ossRe ] 73. Weine , L.M.; Su ana, R.; Wang, S. An ibodies and cance he apy: Ve sa ile pla o ms o cance immuno he apy. Na . Re . Immunol. 2010,10, 317–327. [C ossRe ] [PubMed] 74. Dobson, C.L.; De ine, P.W.A.; Phillips, J.J.; Higazi, D.R.; Lloyd, C.; Popo ic, B.; A nold, J.; Buchanan, A.; Lewis, A.; Goodman, J.; e al. Enginee ing he su ace p ope ies o a human monoclonal an ibody p e en s sel -associa ion and apid clea ance in i o. Sci. Rep. 2016,6, 38644. [C ossRe ] [PubMed] 75. Rodge s, K.R.; Chou, R.C. The apeu ic monoclonal an ibodies and de i a i es: His o ical pe spec i es and u u e di ec ions. Bio echnol. Ad . 2016,34, 1149–1158. [C ossRe ] [PubMed] 76. Shup ine, C.; Su ana, R.; Weine , L.M. Monoclonal An ibodies o he T ea men o Cance . Semin. Cance Biol. 2012,22, 3–13. [C ossRe ] Pha maceu ics 2020,12, 62 20 o 22 77. S oe me , K.A.; Mo ison, T.E. Complemen and Vi al Pa hogenesis. Vi ology 2011 ,411, 362–373. [C ossRe ] 78. Kubo a, T.; Niwa, R.; Sa oh, M.; Akinaga, S.; Shi a a, K.; Hanai, N. Enginee ed he apeu ic an ibodies wi h imp o ed e ec o unc ions. Cance Sci. 2009,100, 1566–1572. [C ossRe ] 79. I ani, V.; Guy, A.J.; And ew, D.; Beeson, J.G.; Ramsland, P.A.; Richa ds, J.S. Molecula p ope ies o human IgG subclasses and hei implica ions o designing he apeu ic monoclonal an ibodies agains in ec ious diseases. Mol. Immunol. 2015,67, 171–182. [C ossRe ] 80. Chames, P.; Van Regenmo el, M.; Weiss, E.; Ba y, D. The apeu ic an ibodies: Successes, limi a ions and hopes o he u u e. B . J. Pha m. 2009,157, 220–233. [C ossRe ] 81. Xenaki, K.T.; Oli ei a, S.; an Be gen en Henegouwen, P.M.P. An ibody o An ibody F agmen s: Implica ions o Molecula Imaging and Ta ge ed The apy o Solid Tumo s. F on . Immunol. 2017,8, 1287. [C ossRe ] 82. Ba es, A.; Powe , C.A. Da id s. Golia h: The S uc u e, Func ion, and Clinical P ospec s o An ibody F agmen s. An ibodies 2019,8, 28. [C ossRe ] 83. B ands ad e , R.; Ka z Sand, I. The use o na alizumab o mul iple scle osis. Neu opsychia . Dis. T ea . 2017 , 13, 1691–1702. [C ossRe ] [PubMed] 84. Lip on, R.B.; Teppe , S.J.; Reu e , U.; Silbe s ein, S.; S ewa , W.F.; Nilsen, J.; Leona di, D.K.; Desai, P.; Cheng, S.; Mikol, D.D.; e al. E enumab in ch onic mig aine. Neu ology 2019 ,92, e2250. [C ossRe ] [PubMed] 85. S ü e, O.; Benne , J.L. Pha macological P ope ies, Toxicology and Scien i ic Ra ionale o he use o Na alizumab (Tysab i®) in In lamma o y Diseases. CNS D ug Re . 2007,13, 79–95. [C ossRe ] [PubMed] 86. Yaldizli, Ö.; Pu zki, N. Na alizumab in he T ea men o Mul iple Scle osis. The . Ad . Neu ol. Diso d. 2009 ,2, 115–128. [C ossRe ] 87. Ohlsson, L.; Haanes, K.A.; K on all, E.; Xu, C.; Snellman, J.; Ed insson, L. E enumab (AMG 334), a monoclonal an agonis an ibody agains he canonical CGRP ecep o , does no impai asodila o y o con ac ile esponses o o he asoac i e agen s in human isola ed c anial a e ies. Cephalalgia 2019 ,39, 1745–1752. [C ossRe ] [PubMed] 88. Goadsby, P.J.; Reu e , U.; Halls öm, Y.; B oessne , G.; Bonne , J.H.; Zhang, F.; Sap a, S.; Pica d, H.; Mikol, D.D.; Lenz, R.A. A Con olled T ial o E enumab o Episodic Mig aine. N. Engl. J. Med. 2017 ,377, 2123–2132. [C ossRe ] [PubMed] 89. Zhou, Q.-H.; Fu, A.; Boado, R.J.; Hui, E.K.-W.; Lu, J.Z.; Pa d idge, W.M. Recep o -media ed abe a amyloid an ibody a ge ing o Alzheime ’s disease mouse b ain. Mol. Pha m. 2011,8, 280–285. [C ossRe ] 90. Zuche o, Y.J.; Chen, X.; Bien-Ly, N.; Bumbaca, D.; Tong, R.K.; Gao, X.; Zhang, S.; Hoy e, K.; Luk, W.; Hun ley, M.A.; e al. Disco e y o No el Blood–b ain Ba ie Ta ge s o Enhance B ain Up ake o The apeu ic An ibodies. Neu on 2016,89, 70–82. [C ossRe ] 91. Sehlin, D.; Sy änen, S.; Ballange , B.; Ba hel, H.; Bischo , G.N.; Boche, D.; Boecke , H.; Bohn, K.P.; Bo ghamme , P.; C oss, D.; e al. Enginee ed an ibodies: New possibili ies o b ain PET? Eu . J. Nucl. Med. Mol. Imaging 2019. [C ossRe ] 92. Camidge, D.R.; Lee, E.Q.; Lin, N.U.; Ma golin, K.; Ahluwalia, M.S.; Bendszus, M.; Chang, S.M.; Dancey, J.; de V ies, E.G.E.; Ha is, G.J.; e al. Clinical ial design o sys emic agen s in pa ien s wi h b ain me as ases om solid umou s: A guideline by he Response Assessmen in Neu o-Oncology B ain Me as ases wo king g oup. Lance Oncol. 2018,19, e20–e32. [C ossRe ] 93. Wang, A.; Komiya, T. B ain me as asis as exclusion c i e ia in clinical ials in ol ing ex ensi e-s age small cell lung cance . J. Cance Res. Clin. Oncol. 2019,145, 3099–3144. [C ossRe ] [PubMed] 94. Baik, C.S.; Chambe lain, M.C.; Chow, L.Q. Ta ge ed The apy o B ain Me as ases in EGFR-Mu a ed and ALK-Rea anged Non-Small-Cell Lung Cance . J. Tho ac. Oncol. 2015,10, 1268–1278. [C ossRe ] [PubMed] 95. Laza o, T.; B as ianos, P.K. Immuno he apy and a ge ed he apy in b ain me as ases: Eme ging op ions in p ecision medicine. CNS Oncol. 2017,6, 139–151. [C ossRe ] [PubMed] 96. Pu emans, J.; Lahou e, T.; D’Huy e e , M.; De oogd , N. Beyond he Ba ie : Ta ge ed Radionuclide The apy in B ain Tumo s and Me as ases. Pha maceu ics 2019,11, 376. [C ossRe ] [PubMed] 97. Zhang, X.; Hao, J. De elopmen o an icance agen s a ge ing he Wn / β -ca enin signaling. Am. J. Cance Res. 2015,5, 2344–2360. [PubMed] 98. Li, Z.; Kang, Y. Eme ging he apeu ic a ge s in me as a ic p og ession: A ocus on b eas cance . Pha macol. The . 2016,161, 79–96. [C ossRe ] Pha maceu ics 2020,12, 62 21 o 22 99. S almans, S.; B acke, N.; Wynendaele, E.; Ge ae , B.; Pe emans, K.; Bu enich, C.; Polis, I.; De Spiegelee , B. Cell-Pene a ing Pep ides Selec i ely C oss he Blood–b ain Ba ie In Vi o. PLoS ONE 2015 ,10, e0139652. [C ossRe ] 100. An ibodySocie y. The apeu ic Monoclonal An ibodies App o ed o in Re iew in he EU o he US. A ailable online: h ps://www.an ibodysocie y.o g/ esou ces/app o ed-an ibodies/(accessed on 5 Decembe 2019). 101. De Angelis, F.; Cha away, J. No el Mul iple Scle osis D ugs in he Pipeline. Clin. Pha macol. The . 2019 ,105, 1082–1090. [C ossRe ] 102. Jo ˇce ska, I.; Muylde mans, S. The The apeu ic Po en ial o Nanobodies. BioD ugs 2019. [C ossRe ] 103. Cummings, J.; Lee, G.; Ri e , A.; Sabbagh, M.; Zhong, K. Alzheime ’s disease d ug de elopmen pipeline: 2019. Alzheime ’s Demen . (N.Y.) 2019,5, 272–293. [C ossRe ] 104. Kaplon, H.; Reiche , J.M. An ibodies o wa ch in 2019. mAbs 2019,11, 219–238. [C ossRe ] [PubMed] 105. Guo, Z.; Peng, H.; Kang, J.; Sun, D. Cell-pene a ing pep ides: Possible ansduc ion mechanisms and he apeu ic applica ions. Biomed. Rep. 2016,4, 528–534. [C ossRe ] [PubMed] 106. A ci, F.G.; Akbulu , B.S.; Ozki imli, E. Memb ane Ac i e Pep ides and Thei Biophysical Cha ac e iza ion. Biomolecules 2018,8, 77. [C ossRe ] [PubMed] 107. Bolin ineanu, D.S.; Kaznessis, Y.N. Compu a ional s udies o p o eg in an imic obial pep ides: A e iew. Pep ides 2011,32, 188–201. [C ossRe ] [PubMed] 108. Madani, F.; Lindbe g, S.; Langel, U.; Fu aki, S.; G äslund, A. Mechanisms o cellula up ake o cell-pene a ing pep ides. J. Biophys. (Hindawi Publ. Co p. Online) 2011,2011, 414729. [C ossRe ] [PubMed] 109. De akhshankhah, H.; Ja a i, S. Cell pene a ing pep ides: A concise e iew wi h emphasis on biomedical applica ions. Biomed. Pha maco he . 2018,108, 1090–1096. [C ossRe ] 110. Zhang, T.-T.; Li, W.; Meng, G.; Wang, P.; Liao, W. S a egies o anspo ing nanopa icles ac oss he blood–b ain ba ie . J. Bioma e . Sci. 2016,4, 219–229. [C ossRe ] 111. F ankel, A.D.; Pabo, C.O. Cellula up ake o he a p o ein om human immunode iciency i us. Cell 1988 , 55, 1189–1193. [C ossRe ] 112. K is ensen, M.; B odin, B. Rou es o d ug ansloca ion ac oss he blood–b ain ba ie : Exploi ing pep ides as deli e y ec o s. J. Pha m. Sci. 2017,S0022-3549, 30361. [C ossRe ] 113. Ducha d , F.; Fo in-Mleczek, M.; Schwa z, H.; Fische , R.; B ock, R. A Comp ehensi e Model o he Cellula Up ake o Ca ionic Cell-pene a ing Pep ides. T a ic2007,8, 848–866. [C ossRe ] 114. Schwa ze, S.R.; Ho, A.; Voce o-Akbani, A.; Dowdy, S.F. In Vi o P o ein T ansduc ion: Deli e y o a Biologically Ac i e P o ein in o he Mouse. Science 1999,285, 1569. [C ossRe ] 115. An oniou, X.; Bo sello, T. Cell Pe meable Pep ides: A P omising Tool o Deli e Neu op o ec i e Agen s in he B ain. Pha maceu ics 2010,3, 379–392. [C ossRe ] [PubMed] 116. Zou, L.-L.; Ma, J.-L.; Wang, T.; Yang, T.-B.; Liu, C.-B. Cell-Pene a ing Pep ide-Media ed The apeu ic Molecule Deli e y in o he Cen al Ne ous Sys em. Cu . Neu opha macol. 2013,11, 197–208. [C ossRe ] 117. Ben-Z i, T.; Yayon, A.; Ge le , A.; Monsonego-O nan, E. Supp esso s o cy okine signaling (SOCS) 1 and SOCS3 in e ac wi h and modula e ib oblas g ow h ac o ecep o signaling. J. Cell Sci. 2006 ,119, 380. [C ossRe ] [PubMed] 118. Demeule, M.; R é gina, A.; Ch é , C.; Poi ie , J.; Nguyen, T.; Gaba hule , R.; Cas aigne, J.-P.; B é li eau, R. Iden i ica ion and Design o Pep ides as a New D ug Deli e y Sys em o he B ain. J. Pha m. Exp. 2008 ,324, 1064. [C ossRe ] 119. Regina, A.; Demeule, M.; T ipa hy, S.; Lachowicz, J. ANG4043, a No el B ain-Pene an Pep ide-mAb Conjuga e, Is E icacious agains HER2-Posi i e In ac anial Tumo s in Mice. Mol. Cance 2015 ,14, 129–140. [C ossRe ] [PubMed] 120. Lim, S.; Kim, W.J.; Kim, Y.H.; Lee, S.; Koo, J.H.; Lee, J.A.; Yoon, H.; Kim, D.H.; Pa k, H.J.; Kim, H.M.; e al. dNP2 is a blood–b ain ba ie -pe meable pep ide enabling c CTLA-4 p o ein deli e y o amelio a e expe imen al au oimmune encephalomyeli is. Na . Commun. 2015,6, 8244. [C ossRe ] 121. Ne es, V.; Ai es-da-Sil a, F.; Mo ais, M.; Gano, L.; Ribei o, E.; Pin o, A.; Aguia , S.; Gaspa , D.; Fe nandes, C.; Co eia, J.D.G.; e al. No el pep ides de i ed om Dengue i us capsid p o ein ansloca e e e sibly he blood–b ain ba ie h ough a ecep o - ee mechanism. ACS Chem. Biol. 2017. [C ossRe ] 122. C ô e-Real, S.; Ne es, V.; Oli ei a, S.; Canh ã o, P.; Ou ei o, T.; Cas anho, M.; Ai es da Sil a, F. An ibody Molecules and Pep ide Deli e y Sys ems o Use in Alzheime ’S Disease and Rela ed Diso de s. WO2016120843A1, 29 Janua y 2016. Pha maceu ics 2020,12, 62 22 o 22 123. Ca aco, M.; Cas anho Miguel, A.R.B.; Ne es, V. Pep ibodies: An elegan solu ion o a long-s anding p oblem. Pep . Sci. 2018,110, e23095. [C ossRe ] 124. Pyzik, M.; Ra h, T.; Lence , W.I.; Bake , K.; Blumbe g, R.S. FcRn: The A chi ec Behind he Immune and Nonimmune Func ions o IgG and Albumin. J. Immunol. 2015,194, 4595. [C ossRe ] 125. Samec, N.; Jo ce ska, I.; S ojan, J.; Zo el, A.; Lio ic, M.; Mye s, M.P.; Muylde mans, S.; Š iba , J.; K ižaj, I.; Komel, R. Glioblas oma-speci ic an i-TUFM nanobody o in- i o immunoimaging and cance s em cell a ge ing. Onco a ge 2018,9, 17282–17299. [C ossRe ] [PubMed] 126. Hu, Y.; Liu, C.; Muylde mans, S. Nanobody-Based Deli e y Sys ems o Diagnosis and Ta ge ed Tumo The apy. F on . Immunol. 2017,8, 1442. [C ossRe ] [PubMed] © 2020 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h p://c ea i ecommons.o g/licenses/by/4.0/).