Second Breath (in silico - validated concept): biomarker-guided sequential local immune programming for desmoplastic tumors

SECOND BREATH (IN SILICO VALIDATED): BIOMARKER-GUIDED LOCAL IMMUNE SEQUENCING FOR DESMOPLASTIC TUMORS Article type: Hypothesis / Concept Paper (Preclinical) Disclaimer: Research concept for discussion and preclinical testing only. This document contains no clinical instructions and is not medical advice. Consent statement/ethical approval: This work does not require ethical approval as there are no proced-ures in human or animal subjects. Funding support: This research did not receive any specific grant from fundingagencies in the public, commercial, or not-for-profit sectors. Ethics statement: This manuscript does not require any ethical review, there is no use of data or manipulations in animals or subjects. Attachments: The manuscript includes 6 figures and 2 tables. Murad Novruzov - corresponding author (ORCID: 0009-0007-2386-6332) E-mail: [email protected] Independent Biomedical Researcher - Azerbaijan, Baku Primary Author & Concept Originator of Second Breath;Project Director responsible for overall concept development, strategic planning, and coordination of all research stages, including in silico and in vivo phases. Developed the hypothesis, cascade design and manages the implementation of the methodology in silico. Keval Raval, PhD (ORCID: 0000-0003-4114-0352) Ramanbhai Patel College of Pharmacy, CHARUSAT University - India, Anand In Silico Modeling Engineer; responsible for the development, execution, and optimization of in silico modeling workflows, data analysis, and integration of computational results into the cascade framework. Ulkar Shiraliyeva, PhD candidate (ORCID: 0009-0005-1314-2774) Azerbaijan State Oil and Industry University - Azerbaijan, Baku Project Member (Chemistry); Participated in the project as an additional contributor from the field of chemistry, supporting the interdisciplinary format of the team and taking part in general discussions during the early development phase. ABSTRACT Background: Despite the success of immune checkpoint inhibitors (ICIs) in certain cancers, many late-stage solid tumors remain “immune-cold,” characterized by low T-cell infiltration, dense extracellular matrix (ECM), stromal and vascular barriers, and poor responses to systemic immunotherapy [4,5,6,7,32,33]. Overcoming these resistance mechanisms requires localized and controlled reprogramming of the tumor microenvironment (TME) to permit effective anti-tumor immunity [4,5]. Objective: The Second Breath strategy proposes a biomarker-guided, staged, and locally confined immune cascade designed to enable reinfiltration and activation of endogenous or autologous T cells in previously unresponsive solid tumors. Methods: Second Breath involves a sequential intervention targeting physical and immunologic barriers. Local enzymatic matrix disruption using a collagenase–hyaluronidase mixture combined with lysyl oxidase inhibition reduces ECM density and stromal barriers [31,32]. Transient recruitment and activation of innate immune cells is induced using weakly immunogenic bacteria or localized toll-like receptor agonists to generate local danger signals [18,19,20,34]. Controlled, microdosed intratumoral cytokine pulses (IL-12, IFN-γ, TNF-α) amplify local antigen presentation and effector T-cell priming priming while minimizing systemic exposure [1,2,9,10,11,21,22,23]. Optional autologous T-cell augmentation can be administered intratumorally or systemically during the window of heightened immune activation [16,17,24,25,26,27]. A recovery or containment phase using local antibiotics or immunomodulators limits excessive inflammation and restores tissue homeostasis after bacteriotherapy [18,19,20,34]. Results: Target validation identified key proteins and genes involved in immune activation, ECM remodeling, and cytokine signaling. Protein–protein interaction analysis revealed densely interconnected hub nodes, including TNF, TLR4, CTLA4, STAT1, and CD274. Functional enrichment highlighted significant involvement of the Wnt signaling pathway, with hub nodes such as APC, LRP5, CTNNB1, and AXIN1 potentially regulating β-catenin activation and cell proliferation. Gene co-occurrence network analysis demonstrated strong interdependencies among IFNG, TLR4, CD86, TNF, NFKB1, CTLA4, and CD8A, suggesting coordinated regulation of immune activation and checkpoint mechanisms within the proposed cascade. Conclusions: Second Breath represents a novel preclinical approach to convert immunologically “cold” tumors into responsive targets for anti-tumor immunity. Its sequential, localized design aims to enhance efficacy while minimizing systemic toxicity. Preclinical network and enrichment analyses provide mechanistic support for its proposed multi-step immune cascade, guiding future in vitro and in vivo validation. Keywords: Tumor microenvironment, immune-cold tumors, intratumoral immunotherapy, extracellular matrix remodeling, autologous T-cell therapy INTRODUCTION Immunologically “cold” solid tumors are defined by low intratumoral CD8⁺ T-cell density, a weak IFN-γ signature, and the presence of abnormal vasculature, elevated interstitial fluid pressure (IFP), and a dense extracellular matrix (ECM) [6,7,32,33]. These features hinder antigen presentation, restrict effector-cell infiltration, and contribute to the poor responsiveness of such tumors to immune checkpoint inhibitors (ICIs) [13,14,15]. To address this challenge, it is hypothesized that sequential local immune programming can effectively convert a cold tumor phenotype into a hot, immunologically active state. This strategy involves PRR-driven innate priming, reinforcement of the IL-12/IFN-γ/TNF-α axis, and controlled ECM modulation, thereby creating favorable conditions for ICI responsiveness while minimizing systemic exposure [1,2,4,5,9,10,11]. This study represents a logical continuation of the article ‘Cascade Medicine: Architecture of Therapy for a Sustainable Outcome’ (M. Novruzov, 2025), where the initial cascade hypothesis was introduced. The conceptual framework proposed for this approach consists of five interrelated modules: (A) local innate priming, (B) local Th1 activation, (C) controlled ECM modulation to reduce IFP and increase tissue porosity, (D) targeted delivery of CD8⁺ T cells and NK cells, and (E) systemic ICI sensitization. Transitions between these modules are guided by local biomarker signals, and readiness for ICI therapy is quantified by a composite Warmth Readiness Index (WRI). This model is particularly relevant for late-stage desmoplastic or exclusionary tumors, which are characterized by substantial physical delivery barriers and an initially cold phenotype [31,32,33]. Despite advances, significant knowledge gaps remain. Intratumoral interventions such as PRR or STING agonists, local IL-12 formulations, and ECM-targeting methods have yielded limited efficacy or unacceptable toxicity under systemic exposure [4,5,9,11]. It is not yet known whether an ordered and biomarker-guided sequence of PRR activation, Th1 reinforcement, and ECM modulation is essential for phenotype conversion and ICI sensitivity. Moreover, operational retention criteria and clear go/no-go rules for such interventions are lacking. The central research question, therefore, is whether biomarker-guided sequential local activation (PRR→Th1→ECM) in immunologically cold, desmoplastic tumors can elevate the WRI above a predefined threshold and improve CD8⁺/NK cell infiltration and ICI sensitivity, compared with either simultaneous delivery of the same components or partial application of individual modules. The primary endpoints include an increase in IFN-γ signature, a reduction in IFP, and enhanced CD8⁺ density per mm² [6,7]. The null hypothesis assumes no measurable differences compared with matched controls. Operationally, an immune-cold tumor is defined by low CD8⁺ infiltration density, a weak IFN-γ signature, low or focal PD-L1 expression, and low tumor mutational burden, combined with a dense ECM and elevated IFP [6,7,32,33]. Stratification relies on a combination of these features, with “cold” tumors classified as those meeting at least two of the three key criteria, with priority given to CD8⁺ density and IFN-γ score. Baseline biomarker monitoring includes CD8⁺/mm², NK signatures, IFN-γ signature, MHC-I/II expression, vascular normalization markers, IFP and perfusion levels, ECM density, TCR clonality, and epitope spreading. Taken together, this framework emphasizes the need for a structured and biomarker-driven strategy to transform immune-cold tumors into responsive phenotypes. By systematically testing whether sequential local immune programming improves tumor immunogenicity and sensitizes tumors to ICIs, this research seeks to close critical gaps in cancer immunotherapy and provide a path toward safer and more effective interventions for desmoplastic and exclusionary tumor types [4,13,14,15,31,32,33]. 2. MATERIALS & METHODS 2.1 Materials 2.1.1 Key Design Principles and Novelty The study was built on three central pillars of novelty. First, local sequential immune programming was designed to engage innate activation, Th1 axis polarization, and controlled ECM remodeling in a stepwise and causal manner, with the goal of converting immune-cold tumors into immune-hot phenotypes [1,2,4,5,9,10,11]. Second, biomarker-gated go/no-go transitions were incorporated to ensure that each stage advanced only upon achieving defined local thresholds, including increases in IFN-γ signature, reductions in IFP with improved perfusion, and enhanced CD8⁺ T-cell density [6,7,32]. Third, a safety-by-design framework was implemented, which emphasized exposure localization and the inclusion of a mandatory antibacterial safety window following bacterial priming to minimize systemic toxicity while maintaining a durable immune imprint [18,19,20,34]. Distinctive elements included the framing of immune pre-conditioning as an investigational stage with defined markers and transition rules, physiologically gentle ECM co-modulation using a combination of collagenase, hyaluronidase, and a lysyl oxidase inhibitor in isotonic saline (0.9% NaCl) [31,32], and protective scaffolding of supportive modules such as NK/IL-15 or extracorporeal measures applied strictly by indication [17,27]. 2.1.2 Classes of Tools Local innate priming (PRR): attenuated bacteria, bacterial patterns, TLR/STING agonists, and PAMP carriers [18,19,20,34]. Local Th1 axis: IL-12 → IFN-γ → TNF-α administered at low, localized exposure with matrix-bound carriers for retention [1,2,9,10,11,21,22,23]. ECM modulation: controlled delivery of collagenase, hyaluronidase, and a lysyl oxidase inhibitor in 0.9% NaCl to reduce IFP and enhance porosity without systemic exposure [31,32]. Effector-cell vectors: autologous or HLA-compatible CD8⁺ T cells and/or NK cells without mandatory genetic modification [16,17,24,25,26,27]. Systemic sensitization: immune checkpoint inhibitors (anti-PD-1/PD-L1, anti-CTLA-4) administered after successful phenotype conversion [13,14,15,28,29,30]. Systemic/supportive therapy: NK-cell products, γc-cytokine support (IL-15 class), crystalloids/plasma, extracorporeal methods, microbiota-directed therapies, and hepatoprotective measures applied strictly under predefined safety indications [17,27]. Antimicrobial protection: antibiotic regimens tailored to the bacterial agent used for PRR priming [18,19,20,34]. 2.1.3 ECM Modulation Mixture A minimal-dose formulation of collagenase, hyaluronidase, and lysyl oxidase inhibitor is proposed for intratumoral delivery in cycles, until biomarker thresholds would indicate ECM remodeling (reduction in IFP and improvement in perfusion). Treatment would be withdrawn upon any indication of over-degradation, vascular compromise, edema, or leakage. 2.1.4 Computational and Bioinformatic Inputs To evaluate pharmacological and genomic influences on cascade progression, an open-source computational toolchain was applied: Chemical & PK/ADME tools: RDKit, Open Babel, SwissADME, pkCSM, admetSAR. Genomics (pharmacogenomics): PharmGKB, CPIC, gnomAD, 1000 Genomes, Ensembl VEP, and SnpEff. Systems/Network analysis: STRING (v11.5), Cytoscape (v3.9.1), cytoHubba plugin, DAVID (v2021), and g:Profiler. Cancer co-occurrence and outcome data: TCGA and cBioPortal. 2.1.5 Preclinical Models Orthotopic, desmoplastic, and immune-excluding tumor models are proposed for preclinical validation to mimic cold tumor microenvironments with delivery barriers [31,32,33]. Intervention arms are designed to include single-step ablations (e.g., PRR only), sequential combinations (PRR→Th1→ECM), and supportive additions (effector cells, ICI). Negative controls were established by switching off PRR pathways, neutralizing IFN-γ, or inhibiting ECM modulators. 2.1.6 Safety and Bioethics All interventions were designed exclusively for preclinical research under IACUC and biosafety oversight. Safety provisions are integrated to include antibacterial phases following PRR priming, cytokine localization with matrix-bound carriers to avoid systemic leakage, controlled ECM modulation to prevent over-degradation, monitoring for hyperinflammatory responses during effector delivery, and strict donor-material compatibility checks for adoptive transfers [9,10,11,18,19,20,24,25,26,27,34]. 2.2 Methods 2.2.1 Sequential Intervention Framework The experimental protocol structured a ten-stage sequence designed to gradually convert immunecold tumors into immune-hot phenotypes. Each stage is defined by a specific goal, transition biomarkers, and safety checks. 1. Immunostimulation (Preparatory): Microbiota, metabolites, and micronutrients were optimized to restore baseline immune competence prior to tumor-directed interventions. Transition to the next stage required normalization of immune parameters and exclusion of active infections. 2. Intratumoral Bacteriotherapy (PRR Priming): Attenuated bacterial preparations or PRR agonists were intended for localized intratumoral delivery in future preclinical settings to activate dendritic cells (DCs) and initiate a local danger cascade [18,19,20,34]. Early increases in IFN-γ signature without systemic inflammation were required to advance. 3. Antibacterial Phase (Safety Window): An antibiotic regimen tailored to the bacterial agent was administered systemically to mitigate sepsis risk while preserving local immune imprinting [18,19,20,34]. 4. Local Anticoagulant Bridge (By Indication): Applied only in cases of hypercoagulability, this stage involved anticoagulant delivery to reduce microthrombosis and vasospasm. Progression required improved coagulation/perfusion markers without bleeding risk. 5. Local Cytokine Axis (IL-12 → IFN-γ → TNF-α): Cytokines were intended for localized intratumoral delivery in future preclinical settings in low doses via matrix-bound carriers to promote Th1 polarization and vascular permeability. Transition required increases in IFN-γ signature and MHC-I/II expression without systemic leakage [1,2,9,10,11,21,22,23]. 6. ECM Modulation: A minimal-dose intratumoral mixture of collagenase, hyaluronidase, and a lysyl oxidase inhibitor in 0.9% NaCl was delivered cyclically to reduce IFP and increase porosity. Advancement required reductions in ECM density and IFP, with improved perfusion but without bleeding or edema. 7. Effector-Cell Administration: Autologous or HLA-compatible CD8⁺ T cells and/or NK cells were administered intratumorally or systemically after barrier relief [16,17,24,25,26,27]. Transition required evidence of infiltration, increased TCR clonality, and absence of hyperinflammation. 8. Personalized Oncovaccination (Optional): Applied selectively to consolidate epitope coverage. Transition required induction of antigen-specific T-cell responses without interference in the base cascade. 9. Supportive Immunomodulation and ICI (Optional): Systemic checkpoint inhibitors (anti-PD-1/PD-L1, anti-CTLA-4) and supportive modules (e.g., NK products, IL-15) were introduced only when biomarker evidence of ICI sensitivity was achieved [13,14,15,28,29,30]. 10. Adjuvant Local Methods (Restricted): Local modalities were reserved for residual lesions after confirming the effects of stages 1–7. 2.2.2 Causal Checks and Go/No-Go Criteria At predefined checkpoints, biomarker thresholds determined whether to proceed, pause, or terminate: After PRR priming: DC activation and early IFN responses [18,19,20,34]. After Th1 axis: Sustained IFN-γ signature without systemic cytokine leakage [1,2,9,10,11]. After ECM modulation: Significant reduction in IFP and increased perfusion [31,32]. After effector delivery: Elevated CD8⁺ T-cell density and cytotoxic activity [16,24,25]. Before ICI initiation: Confirmed transition to a “hot” phenotype (↑ IFN-γ, ↑ infiltration, ↑ PD-L1 expression) [13,14,15]. Safety overrides were triggered by systemic cytokine leakage, ECM over-degradation, microbleeding, edema, or lack of CD8⁺ infiltration despite IFP reduction. 2.2.3 Prediction Matrix and Falsification Criteria To ensure causal attribution, predictions were mapped to specific outcomes: PRR priming → DC activation (assessed by IHC for CD11c and RNA signatures) [18,19,20,34]. IL-12/IFN-γ/TNF-α signaling → “warming” (assessed by IFN-γ score, MHC-I/II upregulation) [1,2,9,10,11]. ECM modulation → improved infiltration (assessed by SHG microscopy, IHC, IFP/perfusion measurements) [31,32]. Effector delivery → tumor control (assessed by growth kinetics, TCR clonality, epitope spreading) [16,24,25]. Warm phenotype → ICI sensitivity (assessed by response analogs such as ORR/PFS in preclinical models) [13,14,15,28,29,30]. Falsification was defined as the absence of predicted biomarker changes compared with matched controls. 2.2.4 In-Silico Modeling and Network Pharmacology To complement preclinical testing, a dynamic cascade simulator (Python/NumPy/Matplotlib code bundle) was applied under the Massive route (PRR→Th1→ECM→Effectors→ICI). Interventions were modeled exclusively with intratumoral local delivery; systemic pharmacokinetics (Cmax, AUC) were analyzed only for antibiotics. Pharmacogenomics integration: Variants in PRR pathways (TLR4, TLR9, STING), cytokine signaling (IFNGR1/2, STAT1), and immune checkpoints (CD274, CTLA4) were mapped from PharmGKB, CPIC, gnomAD, and Ensembl VEP to parameter multipliers in the simulator. Network construction: Candidate gene sets were mapped into protein–protein interaction networks using STRING v11.5. Network topology was analyzed with Cytoscape v3.9.1 and cytoHubba. Functional enrichment: Top hub proteins were subjected to KEGG pathway enrichment via DAVID v2021, with significance at Benjamini-adjusted p < 0.05. Pathway and co-occurrence analysis: Genetic pathway enrichment was cross-validated using TCGA and cBioPortal datasets. Mutual exclusivity and co-occurrence of top hub proteins were assessed across 10,897 tumors spanning 32 cancer types. 2.2.5 Endpoints Primary endpoints: Increase in IFN-γ signature, reduction in IFP, and rise in intratumoral CD8⁺ density [6,7]. Secondary endpoints: TCR clonality, epitope spreading, perfusion/porosity, tumor growth control, survival analogs, and safety of localized exposure (no systemic signal leakage) [4,5,13,14,15,31,32,33]. 3. RESULTS 3.0.1 Supporting in vivo and in vitro evidence from the literature Published experimental studies from other independent groups provide empirical support for each step of the proposed cascade. Enzymatic degradation of extracellular matrix has been shown to reduce interstitial fluid pressure and enhance T-cell infiltration in murine tumor models [31,32]. Local administration of IL-12, IFN-γ, or TNF-α increased antigen presentation and promoted CD8⁺ T-cell priming while minimizing systemic exposure [1,2,9–11,21–23]. Toll-like receptor agonists and attenuated bacterial vectors have successfully triggered local innate immune activation and danger signaling [18–20,34]. Transient containment strategies, including local antibiotics or immunomodulators, have been reported to resolve excessive inflammation following bacteriotherapy [18–20]. Collectively, these in vivo and in vitro observations [1–34] confirm the feasibility of the individual modules, providing a biological foundation for the subsequent in silico network validation of the full Second Breath cascade. 3.0.2 In silico validation 3.1 Target Validation A list of proteins/genes corresponding to each set is summarized in Table 1. Table 1: List of proteins/genes corresponding to different routes Route List of genes Massive Route TLR4, LY96, TLR9, MB21D1, TMEM173, MYD88, TICAM1, TBK1, IRF3, IRF7, NFKB1, RELA, CD80, CD86, CCR7, IL12A, IL12B, IL12RB1, IL12RB2, STAT4, IFNG, IFNGR1, IFNGR2, JAK1, JAK2, STAT1, TNF, TNFRSF1A, TNFRSF1B, MAP3K7, NFKBIA, COL1A1, COL3A1, HAS2, HYAL1, HYAL2, LOX, MMP2, MMP9, ICAM1, VCAM1, VEGFA, KDR, ANGPT1, ANGPT2, TEK, CD8A, CD8B, PRF1, GZMB, KLRK1, MICA, MICB, HLA-A, HLA-B, B2M, TAP1, TAP2, CTSS, PDCD1, CD274, CTLA4, CD80, CD86, LAG3, TIGIT, HAVCR2 3.2 Protein-Protein Interactions Massive The base network was generated from the defined target list, forming discrete, module-specific clusters. STRING enrichment produced an enriched network with dense interconnectivity, indicating extensive functional relationships. Hub analysis (degree >10) identified the top 10 key nodes including TNF, TLR4, CTLA4, STAT1, and CD274 - representing critical regulators within the Massive route cascade. 5. CONCLUSION This multi-layered in silico investigation combining network pharmacology, functional enrichment, and co-occurrence analyses provides a systems-level perspective on the mechanistic underpinnings of the Massive immunological route. PPI network analysis identified central hub proteins, such as IFNG, TNF, CTLA4, CD86, and STAT1, forming the backbone of each route’s regulatory framework. Functional enrichment revealed that these hubs are embedded in distinct but complementary pathways: the Massive route prominently engages Wnt signaling with proliferative and immunoregulatory processes. Co-occurrence network mapping further demonstrated that these hub proteins exhibit strong functional interdependencies, with recurrent high-frequency associations linking immune checkpoint regulators, cytokines, and co-stimulatory molecules. 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