Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2026

A phase 2/3 trial of a PD-1/VEGF bispecific antibody (PF-08634404) in combination with chemotherapy in first-line for extensive-stage small cell lung cancer (ES-SCLC; Symbiotic-Lung-04)  (145940)

Federico Capuzzo 1 , Eric S Schaefer 2 , Yuta Yamanaka 3 , Bryan A Chan 4 , Adnan Nagrial 5 , Yi-Long Wu 6 , David Planchard 7 , Stefanie Gropper 8 , Pedro Rocha 9 , Silvia Novello 10 , Jennifer Park 11 , Mo Huang 12 , Afshin Dowlati 13
  1. National Cancer Institute Regina Elena, Rome, Italy
  2. Highlands Oncology Group, Fayetteville, AR, United States
  3. Kansai Medical University Hospital, Osaka, Japan
  4. Sunshine Coast University Hospital, Birtinya, Queensland, Australia
  5. Westmead Hospital, Sydney, Australia
  6. Guangdong Provincial People's Hospital & Guangdong Academy of Medical Sciences, Guangdong, China
  7. Medical Oncology, Thoracic Group, Gustave Roussy, Villejuif, France
  8. Marien Hospital Dusseldorf, Dusseldorf, Germany
  9. Vall d'Hebron University Hospital, Barcelona, Spain
  10. Oncology, AOU San Luigi, University of Turin, Turin, Italy
  11. Pfizer, Bothell, WA, United States
  12. Pfizer, Collegeville, PA, United States
  13. University Hospitals Cleveland Medical Center, Cleveland, OH, United States

Background: PF-08634404 is a fully human IgG4 bispecific antibody that simultaneously targets PD-1 and VEGF. Phase 2 studies have shown promising efficacy and manageable safety with PF-08634404 as a monotherapy and with chemotherapy in first-line NSCLC. This study will evaluate the outcomes of PF-08634404 in combination with chemotherapy in ES-SCLC.  

Trial design: Symbiotic-Lung-04 is a phase 2/3 trial (NCT07226999) in adult patients with histologically confirmed ES-SCLC who have not received prior systemic therapy. Patients must have measurable disease per RECIST 1.1, ECOG performance status of 0 or 1, and life expectancy ≥3 months. Patients with active CNS lesions or leptomeningeal disease are excluded. Patients may receive 1 cycle of chemotherapy without immune checkpoint inhibitors before enrollment for the management of life-threatening ES-SCLC. 

The phase 2 portion is an open-label, multicenter, dose expansion study to confirm the recommended phase 3 dose (RP3D) and evaluate safety, tolerability, and preliminary efficacy of PF-08634404 plus chemotherapy. Approximately 40 patients will receive PF-08634404 plus carboplatin and etoposide for 4 cycles followed by PF-08634404 monotherapy. Primary endpoints are confirmed objective response rate (ORR) by investigator assessment per RECIST 1.1 and safety. Secondary endpoints include duration of response (DOR) and progression-free survival (PFS) by investigator, overall survival (OS), and dose-limiting toxicities. Phase 2 enrollment has begun. 

The phase 3 portion is a double-blind, randomized study to evaluate the efficacy and safety of PF-08634404 plus chemotherapy versus anti–PD-L1 plus chemotherapy. Approximately 500 patients will be randomized 1:1 to receive PF-08634404 at RP3D or anti–PD-L1 plus carboplatin and etoposide for 4 cycles followed by maintenance therapy with PF-08634404 or anti–PD-L1. The primary endpoint is OS. Secondary endpoints include PFS, confirmed ORR, and DOR by blinded independent central review and safety.  

Previously presented at ELCC 2026, FPN: 440TiP, Federico Cappuzzo et al. - Reused with permission