Phase 2 PF-08634404 PD‑1×VEGF bispecific antibody with platinum-etoposide in T‑SCLC.

Pfizer’s Phase 2, open-label Symbiotic‑Lung‑14 study tests PF‑08634404, a PD‑1 and VEGF‑targeted bispecific antibody intended to combine checkpoint blockade with anti-angiogenic signaling inhibition, in adults with transformed small cell lung cancer (T‑SCLC) arising after EGFR‑mutated NSCLC treated with EGFR tyrosine kinase inhibitors. Participants who are previously untreated for T‑SCLC (a single chemo cycle may be allowed) receive PF‑08634404 by IV in combination with chemotherapy, then continue PF‑08634404 as maintenance monotherapy. The main goal is to characterize anti-tumor activity and safety of bringing dual PD‑1/VEGF biology into this rare, clinically aggressive post‑TKI transformation setting. Scientifically, it targets an immune-evasive and angiogenesis-driven phenotype in a population typically excluded from mainstream SCLC trials and often lacking durable options after transformation. Today’s care for T‑SCLC commonly mirrors de novo SCLC first-line treatment—platinum plus etoposide (sometimes with a PD‑L1 inhibitor by extrapolation)—followed by rapid relapse and limited later-line benefit, so this trial probes whether a next-generation PD‑1×VEGF immuno-antiangiogenic approach can extend control beyond chemotherapy alone.