AK157D1 NMPA Clearance: Phase 1 Entry Into a B7-H3 ADC Race Already Defined by Rivals

Limited efficacy of conventional therapies: Surgery, radiotherapy, and chemotherapy yield only modest survival benefits in high-mortality tumor types such as pancreatic cancer, which is projected to become the second leading cause of cancer-related death by 2030, underscoring the urgent need for more effective systemic approaches.

Poor immunotherapy response in immunologically "cold" tumors: Single-agent immune checkpoint inhibitors (ICIs) demonstrate objective response rates below 5% in MSS/pMMR CRC — which represents more than 85% of colorectal cancer cases — and have similarly shown disappointing efficacy in PDAC and ACC, reflecting profound intrinsic resistance across these histologies.

Immunosuppressive tumor microenvironment (TME): A durable immunosuppressive axis — driven by tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs) — promotes immune evasion, tumor progression, metastasis, and chemoresistance through multilayered mechanisms including bidirectional chemotactic recruitment, reciprocal cytokine signaling, metabolic suppression, and exosome-mediated communication.

Physical and molecular barriers to immune infiltration: In PDAC specifically, aberrant vasculature, cancer-associated fibroblasts (CAFs), and excessive hyaluronic acid deposition impede immune cell infiltration, while low tumor mutational burden combined with KRAS mutations and MYC overexpression further diminishes tumor immunogenicity and antitumor immune priming.

Acquired resistance to targeted therapies: In FGFR-targeted treatment, secondary mutations, activation of bypass signaling pathways, and intratumoral heterogeneity collectively drive acquired resistance, limiting the durability of initial responses.

Treatment-related toxicity burden: Immune-related adverse events (irAEs) of all grades developed in 27.0% of ICI-treated patients, with grade ≥3 events in 10.7%; cumulative irAE rates reached 43.0% by 20 cycles. In separate analyses, 29.24% of patients discontinued immunotherapy due to irAEs. Ramucirumab use was associated with a significantly elevated risk of serious adverse events (RR 1.13, 95% CI 1.05–1.21; incidence 37.5% vs. 33.5%).

Marginal clinical benefit of approved agents: Assessed using the ESMO Magnitude of Clinical Benefit Scale (MCBS), ramucirumab failed to demonstrate substantial clinical benefit across any of its approved indications — with five of six approvals receiving a "negligible benefit" score of 1 or 2 — and quality of life was either unreported (30%) or unimproved (70%) across its randomized controlled trials.