Boehringer's $358M Bet on Six Blind Preclinical ADCs Tests Discipline

Next-generation co-inhibitory and co-stimulatory checkpoints: lymphocyte activation gene-3 [LAG-3], T cell immunoglobulin and mucin-domain containing-3 [TIM-3], TIGIT, VISTA, and IGSF8, alongside ICOS, OX40, GITR, 4-1BB, CD40, and CD27 that regulate the balance between immune activation and tolerance, particularly in ICI-refractory settings.

TME remodeling and innate immune activation: targeting immunometabolic pathways (IDO1 and CD73), innate immune sensing (toll-like receptors [TLRs] and stimulator of interferon genes [STING] signaling in combination with immune checkpoint blockade), cytokine signaling (IL-2), micronutrient immunoregulators (vitamin D), and gut microbiota.

Adoptive cell therapy expansion: lymphokine-activated killer cells (LAK), tumor-infiltrating lymphocytes (TIL), cytokine-induced killer cells (CIK), dendritic cells (DC), T cell receptor-modified T cells (TCR-T), chimeric antigen receptor T cells (CAR-T), natural killer (NK) cells, chimeric antigen receptor-modified NK cells (CAR-NK), and CAR-M, with universal CAR structural optimization, iPSC-derived cell products, multifunctional CAR design, and AI-assisted antigen screening.

Bispecific T-cell engagers: EGFR-Vδ2 bispecific T-cell engager directing Vγ9Vδ2 T cells to EGFR-expressing tumors, inducing downstream activation of CD4+ and CD8+ T cells and natural killer (NK) cells.

Antibody-drug conjugates for solid tumors: CDH17-targeted ADC 7MW4911 incorporating topoisomerase inhibitor MF-6 via cleavable linker, tissue factor ADC ADCE-T02 comprising monoclonal antibody Ab-T02 conjugated via self-immolative linker to Topoisomerase-1 inhibitor Exatecan at average drug-to-antibody ratio of 4.5, and B7-H3-directed programs.

KRAS beyond G12C and targeted protein degradation: KRAS G12D inhibitors, pan-RAS and RAS(ON) inhibitors, including Setidegrasib (ASP3082) proteolysis-targeting chimera molecule targeting KRAS G12D mutation and Daraxonrasib (RMC-6236) pan-RAS inhibitor targeting all ON-state RAS via tri-complex/molecular glue spanning Switch I and Switch II regions, plus PROTACs, molecular glue, and hydrophobic tagging degraders targeting epigenetic proteins and EGFR C797S/L858R/T790M mutations.

Radionuclide-based therapy: lutetium-177 (Lu) targeted radionuclide therapy emitting both γ and β rays, allowing imaging with single photon emission computed tomography and tumor treatment in metastatic prostate cancer, neuroendocrine tumors and other solid tumors.

Acquired resistance limits therapeutic durability, including for antibody-drug conjugates, with 4 FDA-approved agents to date, and 15 for the entire cancer landscape, and for PD-1/PD-L1 inhibitors where emergence of intrinsic or acquired resistance warrants investigation and management.

Narrow therapeutic index and systemic toxicity, due to agents that may damage not only cancer cells, but also normal and healthy tissue, dose-limiting systemic toxicity of cytokines, and a narrow therapeutic window requiring lower dosage strategies to reduce off-target toxicity.

Intratumor heterogeneity and clonal evolution, with genetically diverse cell subpopulations, branched trajectory with divergent subclones evolving simultaneously, and shifting clonal populations that drive tumor progression, chemoresistance and relapse; acquired or intrinsic drug resistance is responsible for almost 90% of treatment failure.

Tumor microenvironment barriers to delivery and immune activity, where stromal architecture, vascular heterogeneity, and immune modulation intersect with clonal evolution, phenotypic plasticity, and pathway reprogramming, and stromal components establish physical barriers and foster immunosuppressive niches that facilitate tumor immune evasion; efficacy remains dependent on T cell infiltration into the tumor microenvironment with response rate remaining relatively low (<30%).

Immune-related adverse events and precision-monitoring constraints, with incidence of irAEs was 42.1% in patients treated with anti-programmed cell death 1(PD-1)/PD-1 ligand (PD-L1) inhibitors, and widespread NGS adoption constrained by technical limitations (e.g., coverage uniformity and sample quality), economic challenges (high costs and complex reimbursement), and interpretative issues, including the management of variants of uncertain significance (VUSs).

DNA damage response and S-G(2) checkpoint regulation: Checkpoint kinase 1 (Chk1) is described as a key element in the DNA damage response pathway with a crucial role in the S-G(2)-phase checkpoints, with PF-00477736 identified as a potent, selective ATP-competitive small-molecule inhibitor that inhibits Chk1 with a K(i) of 0.49 nM. PF-00477736 abrogates cell cycle arrest induced by DNA damage and enhances cytotoxicity of gemcitabine and carboplatin, and in xenografts enhanced the antitumor activity of gemcitabine in a dose-dependent manner. Additional regulation includes glycogen synthase kinase 3 β (GSK3B) governing DNA double-strand break repair pathway choice by phosphorylating 53BP1 at threonine 334 (T334), and lysine demethylase 4A (KDM4A) catalyzing truncation removing two C-terminal amino acids critical for ATM/ATR-dependent phosphorylation of histone H2AX at serine 139.

Cell-surface targets for antibody-drug conjugates: Lymphocyte antigen 6 complex locus E (LY6E), an IFN-inducible glycosylphosphatidylinositol (GPI)-linked cell membrane protein, was overexpressed and amplified with high protein expression in breast, lung, gastric, ovarian, pancreatic, kidney and head/neck carcinomas. Delta-like canonical notch ligand 1 (DLK1) was prioritized as an immunotherapeutic target in neuroblastoma, with ADCT-701 showing potent and specific cytotoxicity in DLK1-expressing neuroblastoma xenograft models, and highly expressed in adrenocortical carcinoma (ACC), pheochromocytoma/paraganglioma (PCPG), hepatoblastoma, and small cell lung cancer (SCLC). Other ADC approaches include carbonic anhydrase (CAIX) targeted delivery potentiated by inhibition of glycosaminoglycan biosynthesis with xylosides, CD30 targeted by brentuximab vedotin for relapsed Hodgkin and systemic anaplastic large cell lymphomas, and an anti-epidermal growth factor receptor (EGFR) × cotinine bispecific antibody mixed with cotinine-conjugated duocarmycin active against EGFR-positive, cetuximab-refractory lung adenocarcinoma cells with KRAS mutations.

Next-generation immune checkpoints and tumor microenvironment modulation: Co-inhibitory pathways include lymphocyte activation gene-3 [LAG-3], T cell immunoglobulin and mucin-domain containing-3 [TIM-3], TIGIT, VISTA, and IGSF8, and co-stimulatory pathways include ICOS, OX40, GITR, 4-1BB, CD40, and CD27. Complementary strategies include targeting immunometabolic pathways (IDO1 and CD73), innate immune sensing (toll-like receptors [TLRs]), cytokine signaling (IL-2), micronutrient immunoregulators (vitamin D), and the gut microbiota, guided by T cell infiltration, tumor mutational burden (TMB), and microbiome composition.

Metabolic, transcriptional and stromal regulators: The C1 NDUFAB1+ subtype in gastric cancer exhibited high proliferative activity, metabolic reprogramming capabilities, and immune evasion properties, with ELK4 identified as a key regulatory factor and knockdown substantially curbing tumor cell proliferation, migration, and invasion. Aldolase A (ALDOA) was significantly overexpressed with elevated expression correlated with poor overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in lung squamous cell carcinoma, with ALDOA-high tumors showing increased M0 macrophage and reduced CD8+ T-cell infiltration and co-localization with CD68+ tumor-associated macrophages. Ten prognosis-related itaconate and Hallmark pathway-related genes (TIMP1, FJX1, CD36, CXCL1, ETS2, CDKN2A, INHBB, PLEC, TUBB2, and P4HA1) were selected from 448 colon cancer patients, and EphA3 was expressed in the tumor microenvironment in glioblastoma with ifabotuzumab targeting showing chronological stable expression across tumour and non-tumour compartments.