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PF-08634404 plus chemotherapy for extensive-stage small cell lung cancer

A GLOBAL PHASE 2/3 INTERVENTIONAL STUDY OF PF-08634404 IN COMBINATION WITH CHEMOTHERAPY IN PARTICIPANTS WITH EXTENSIVE STAGE SMALL CELL LUNG CANCER

Phase2; Phase3 Interventional Pfizer · NCT07226999

This study will try adding PF-08634404 to chemotherapy in adults with extensive-stage small cell lung cancer to see if it works better than current first-line treatment.

Quick facts

PhasePhase2; Phase3
Study typeInterventional
Enrollment550 (estimated)
Ages18 Years and up
SexAll
SponsorPfizer Industry-sponsored
Drugs / interventionschemotherapy, atezolizumab, radiation
Locations32 sites (Fayetteville, Arkansas and 31 other locations)
Trial IDNCT07226999 on ClinicalTrials.gov

What this trial studies

The trial enrolls adults with newly diagnosed extensive-stage small cell lung cancer and gives PF-08634404 together with standard chemotherapy by IV. It has an initial safety/tolerability phase to determine how the medicine is handled with chemotherapy, followed by a randomized phase comparing PF-08634404 plus chemotherapy to the approved combination of atezolizumab plus chemotherapy. Participants must have measurable disease, good performance status (ECOG 0–1), and adequate organ function; treatments and follow-up visits occur at participating clinic sites. Outcomes include safety, tolerability, and comparative clinical outcomes such as tumor response and disease control.

Who should consider this trial

Good fit: Adults (≥18) with lab-confirmed extensive-stage small cell lung cancer who have not received prior systemic treatment for ES-SCLC, have ECOG 0–1, measurable disease, and adequate organ function are ideal candidates.

Not a fit: Patients with active central nervous system metastases, leptomeningeal disease, recent other malignancies, active autoimmune disease needing systemic treatment, poor organ function, or ECOG >1 are unlikely to qualify or benefit from this protocol.

Why it matters

Potential benefit: If successful, adding PF-08634404 to chemotherapy could improve response rates or survival compared with current first-line therapy.

How similar studies have performed: Previous trials adding immunotherapy to chemotherapy (for example atezolizumab) have modestly improved outcomes in first-line ES-SCLC, but PF-08634404 is a new agent with limited prior clinical data.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Histologically or cytologically confirmed extensive-stage small cell lung cancer (ES-SCLC).
* Participants have not received systemic therapy (chemotherapy, radiotherapy, chemoradiation) for ES-SCLC.
* Treatment-free for at least 6 months since last chemo/radiotherapy, among those treated (with curative intent) with prior chemo/radiotherapy for limited-stage SCLC
* Have at least one measurable lesion as the targeted lesion based on RECIST V1.1.
* Eastern Cooperative Oncology Group performance status of 0 or 1.
* Adequate organ function

Exclusion Criteria:

* known active CNS lesions, including brainstem, meningeal, or spinal cord metastases or compression
* Leptomeningeal disease
* Clinically significant risk of hemorrhage or fistula
* history of another malignancy within 3 years
* active autoimmune diseases requiring systemic treatment within the past 2 years

Where this trial is running

Fayetteville, Arkansas and 31 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Small Cell Lung Cancersmall cell lung cancerextensive stage small cell lung cancerfirst-line
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.