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Small Cell Lung Cancer (SCLC)Phase 2/3NCT07226999

Symbiotic-Lung-04: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Adult Participants With Extensive-Stage Small Cell Lung Cancer

A Phase 2/3 study testing PF-08634404, Atezolizumab and Chemotherapy in people with Small Cell Lung Cancer (SCLC), run by Pfizer at 82 sites in 10 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
Search all trials

Trial summary

This study is being done to learn more about a new medicine called PF-08634404 and how well it works when given with chemotherapy to adults with extensive-stage small cell lung cancer (ES-SCLC), a fast-growing type of lung cancer that has spread widely in the body. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Small Cell Lung Cancer (SCLC)
What is being tested?
PF-08634404, Atezolizumab and Chemotherapy
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
550 participants
Where
82 sitesin 10 countries
Study dates
9 Dec 2025to 11 Mar 2034
Phase
Phase 2/3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • 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

Who cannot join

  • 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

Trial locations and contacts

82 sites in 10 countries. Contact the study team or a site near you to ask about taking part.

Pfizer CT.gov Call Center contact

1-800-718-1021

ClinicalTrials.gov_Inquiries@pfizer.com

82 sites in 10 countries

United States54 sites, 54 recruiting

  • Texas Oncology - Northeast Texas

    Allen, Texas, 75013

    Recruiting

  • Texas Oncology - DFW

    Arlington, Texas, 76012

    Recruiting

  • Texas Oncology - DFW

    Arlington, Texas, 76014

    Recruiting

  • Texas Oncology - Gulf Coast

    Beaumont, Texas, 77702

    Recruiting

  • Texas Oncology - DFW

    Bedford, Texas, 76022

    Recruiting

  • Oncology & Hematology Associates of Southwest Virginia, Inc., DBA Blue Ridge Cancer Care

    Blacksburg, Virginia, 24060

    Recruiting

  • Virginia Oncology Associates

    Chesapeake, Virginia, 23320

    Recruiting

  • University Hospitals Cleveland Medical Center

    Cleveland, Ohio, 44106

    Recruiting

  • BRCR Coral Springs

    Coral Springs, Florida, 33065

    Recruiting

  • Texas Oncology - DFW

    Dallas, Texas, 75203

    Recruiting

  • Texas Oncology - DFW

    Dallas, Texas, 75230

    Recruiting

  • Texas Oncology - DFW

    Dallas, Texas, 75231

    Recruiting

  • Texas Oncology - DFW

    Dallas, Texas, 75237

    Recruiting

  • Texas Oncology - DFW

    Dallas, Texas, 75246

    Recruiting

  • Texas Oncology - Northeast Texas

    Denison, Texas, 75020

    Recruiting

  • Texas Oncology - Northeast Texas

    Denton, Texas, 76201

    Recruiting

  • Highlands Oncology Group

    Fayetteville, Arkansas, 72703

    Recruiting

  • Texas Oncology - Northeast Texas

    Flower Mound, Texas, 75028

    Recruiting

  • Texas Oncology - DFW

    Fort Worth, Texas, 76104

    Recruiting

  • Texas Oncology - San Antonio

    Fredericksburg, Texas, 78624

    Recruiting

  • Texas Oncology - DFW

    Grapevine, Texas, 76051

    Recruiting

  • Virginia Oncology Associates

    Hampton, Virginia, 23666

    Recruiting

  • Texas Oncology - Gulf Coast

    Houston, Texas, 77024

    Recruiting

  • Texas Oncology - Gulf Coast

    Houston, Texas, 77054

    Recruiting

  • US Oncology Investigational Product Center (IPC)

    Irving, Texas, 75063

    Recruiting

  • US Oncology Investigational Products Center (IPC)

    Irving, Texas, 75063

    Recruiting

  • Texas Oncology - Northeast Texas

    Lewisville, Texas, 75056

    Recruiting

  • Texas Oncology - Northeast Texas

    Longview, Texas, 75601

    Recruiting

  • Oncology & Hematology Associates of Southwest Virginia, Inc., DBA Blue Ridge Cancer Care

    Low Moor, Virginia, 24457

    Recruiting

  • Texas Oncology - Northeast Texas

    McKinney, Texas, 75071

    Recruiting

  • Texas Oncology - San Antonio

    New Braunfels, Texas, 78130

    Recruiting

  • Virginia Oncology Associates

    Newport News, Virginia, 23606

    Recruiting

  • Virginia Oncology Associates

    Norfolk, Virginia, 23502

    Recruiting

  • Mid Florida Hematology and Oncology Center

    Orange City, Florida, 32763

    Recruiting

  • Texas Oncology - Northeast Texas

    Palestine, Texas, 75801

    Recruiting

  • Texas Oncology - Northeast Texas

    Paris, Texas, 75460

    Recruiting

  • Texas Oncology - Gulf Coast

    Pearland, Texas, 77584

    Recruiting

  • Texas Oncology - DFW

    Plano, Texas, 75075

    Recruiting

  • Texas Oncology - DFW

    Plano, Texas, 75093

    Recruiting

  • Oncology & Hematology Associates of Southwest Virginia, Inc., DBA Blue Ridge Cancer Care

    Roanoke, Virginia, 24014

    Recruiting

  • Highlands Oncology Group

    Rogers, Arkansas, 72758

    Recruiting

  • Oncology & Hematology Associates of Southwest Virginia, Inc., DBA Blue Ridge Cancer Care

    Salem, Virginia, 24153

    Recruiting

  • Texas Oncology - San Antonio

    San Antonio, Texas, 78217

    Recruiting

  • Texas Oncology - San Antonio

    San Antonio, Texas, 78240

    Recruiting

  • Texas Oncology - San Antonio

    San Antonio, Texas, 78258

    Recruiting

  • Highlands Oncology Group

    Springdale, Arkansas, 72762

    Recruiting

  • Texas Oncology - Gulf Coast

    Sugar Land, Texas, 77479

    Recruiting

  • BRCR Global - Tamarac

    Tamarac, Florida, 33321

    Recruiting

  • Texas Oncology - Gulf Coast

    The Woodlands, Texas, 77380

    Recruiting

  • Texas Oncology - Northeast Texas

    Tyler, Texas, 75702

    Recruiting

  • Virginia Oncology Associates

    Virginia Beach, Virginia, 23456

    Recruiting

  • Texas Oncology - Gulf Coast

    Webster, Texas, 77598

    Recruiting

  • Virginia Oncology Associates

    Williamsburg, Virginia, 23188

    Recruiting

  • Oncology & Hematology Associates of Southwest Virginia, Inc., DBA Blue Ridge Cancer Care

    Wytheville, Virginia, 24382

    Recruiting

Other trials in United States

Spain7 sites, 7 recruiting

  • Parc de Salut Mar - Hospital del Mar

    Barcelona, 08003

    Recruiting

  • CETIR

    Barcelona, 08029

    Recruiting

  • Hospital Universitari Vall d'Hebron

    Barcelona, 08035

    Recruiting

  • HT Médica Jaen LAs Nieves

    Jaén, Andalusia, 23007

    Recruiting

  • Hospital Universitario de Jaen

    Jaén, 23007

    Recruiting

  • Hospital Jerez de la Frontera

    Jerez de la Frontera, Cádiz, 11407

    Recruiting

  • Hospital Universitario 12 de Octubre

    Madrid, Madrid, Comunidad de, 28041

    Recruiting

Other trials in Spain

Puerto Rico4 sites, 4 recruiting

  • Doctor's Center Hematology & Oncology Group

    Manati, 00674

    Recruiting

  • Pan American Center for Oncology Trials, LLC - Mayaguez Office Mayaguez Medical Center

    Mayagüez, 00680

    Recruiting

  • Pan American Center for Oncology Trials LLC

    San Juan, 00909

    Recruiting

  • Hospital Oncologico Dr. Isaac Gonzalez-Martinez

    San Juan, 00935

    Recruiting

Other trials in Puerto Rico

Italy3 sites, 3 recruiting

  • Centro di Riferimento Oncologico (CRO) IRCCS

    Aviano, Pordenone, 33081

    Recruiting

  • Azienda Ospedaliero-Universitaria San Luigi Gonzaga

    Orbassano, Turin, 10043

    Recruiting

  • IRCCS Istituto Nazionale dei Tumori Regina Elena

    Roma, ROME, 00144

    Recruiting

Other trials in Italy

Japan3 sites, 3 recruiting

  • Kansai Medical University Hospital

    Hirakata, Osaka, 573-1191

    Recruiting

  • Japanese Foundation for Cancer Research

    Kotoku, Tokyo, 135-8550

    Recruiting

  • Shizuoka Cancer Center

    Nagaizumi-cho, Shizuoka, 411-8777

    Recruiting

Other trials in Japan

Taiwan3 sites, 3 recruiting

  • National Cheng Kung University Hospital

    Tainan, 704302

    Recruiting

  • National Taiwan University Hospital

    Taipei, 10002

    Recruiting

  • Taipei Medical University Hospital

    Taipei, 110

    Recruiting

Other trials in Taiwan

Australia2 sites, 2 recruiting

  • Sunshine Coast University Hospital

    Birtinya, Queensland, 4575

    Recruiting

  • Westmead Hospital

    Westmead, New South Wales, 2145

    Recruiting

Other trials in Australia

China2 sites, 2 recruiting

  • Guangdong Provincial People's Hospital

    Guangzhou, Guangdong, 510180

    Recruiting

  • Fudan University Shanghai Cancer Center

    Shanghai, Shanghai Municipality, 200032

    Recruiting

Other trials in China

France2 sites, 2 recruiting

  • Hôpital Ambroise Paré

    Boulogne-Billancourt, Île-de-France Region, 92100

    Recruiting

  • Gustave Roussy

    Villejuif, 94805

    Recruiting

Other trials in France

Germany2 sites, 2 recruiting

  • Marien Hospital Düsseldorf

    Düsseldorf, 40479

    Recruiting

  • Krankenhaus Nordwest GmbH

    Frankfurt am Main, 60488

    Recruiting

Other trials in Germany

About this study

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

This study is being done to learn more about a new medicine called PF-08634404 and how well it works when given with chemotherapy to adults with extensive-stage small cell lung cancer (ES-SCLC), a fast-growing type of lung cancer that has spread widely in the body.

To join the study, participants must meet the following conditions:

Read more
  • Be 18 years or older.
  • Have extensive-stage small cell lung cancer confirmed by lab tests.
  • Have not received chemotherapy or radiation for this type of lung cancer.
  • Be in good physical condition and have healthy organs based on medical tests.

The study has two parts:

  • In the first part, researchers will check how safe the study medicine is and how well people tolerate it when given with chemotherapy.
  • In the second part, they will compare study medicine plus chemotherapy to another approved treatment (atezolizumab plus chemotherapy) to see which works better.

Participants will receive the treatment through IV infusions (medicine given directly into a vein). The treatment will be given in repeated time periods called cycles. Some participants will continue receiving the study medicine alone after the initial treatment.

Being tested
PF-08634404, Atezolizumab, Chemotherapy
Keywords
small cell lung cancer, extensive stage small cell lung cancer, first-line
Medical subject headings
Small Cell Lung Carcinoma

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • PF-08634404Drug

    Concentrate for solution for infusion

  • AtezolizumabBiological

    Injection for intravenous use

  • ChemotherapyDrug

    Injection for intravenous use

Study groups in NCT07226999
Study groupRoleWhat they receive
Phase 2 Single armExperimentalParticipants will receive PF-08634404 in combination with chemotherapy
Receives: Drug: PF-08634404; Drug: Chemotherapy
Phase 3 Experimental ArmExperimentalParticipants will receive PF-08634404 in combination with chemotherapy
Receives: Drug: PF-08634404; Drug: Chemotherapy
Phase3 Control ArmActive comparatorParticipants will receive atezolizumab in combination with chemotherapy
Receives: Biological: Atezolizumab; Drug: Chemotherapy

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Phase 2: Confirmed Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors version 1.1 [RECIST 1.1] based on the investigator's assessment

    Defined as the proportion of participants in whom a confirmed complete response (CR) or partial response (PR) is observed as best overall response. ORR using RECIST v1.1 as assessed by investigator.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  2. Phase 2: Number of participants with treatment-emergent adverse events

    Adverse Events (AEs) as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), timing, seriousness, and relationship to study intervention.

    Measured: Up to 90 days after the last dose of treatment

  3. Phase 3: Overall Survival (OS)

    OS is defined as the time from the date of randomization to the date of death due to any cause. OS is secondary outcome measure in Phase 2 portion of the study.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

Secondary outcomes (14)

  1. Duration of Response (DOR) as assessed by Investigator based on RECIST v1.1

    DOR is defined as the time from the first documentation of objective response (CR or PR) to the date of first documentation of progressive disease (PD) or death due to any cause.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  2. Progression Free Survival (PFS) as assessed by investigator based on RECIST v1.1

    PFS is defined as the time from the date of randomization to the date of first documented disease progression, per RECIST v1.1, or death to any cause, whichever occurs first

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  3. Number of participants with Laboratory abnormalities

    Laboratory abnormalities as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), and timing.

    Measured: Up to 90 days after the last dose of treatment

  4. Phase 2: Number of Participants who Experience a Dose-Limiting Toxicity (DLT)

    DLT (any of the prespecified AEs that are attributable to study treatment(s), excluding toxicities clearly due to underlying disease or extraneous causes) rate estimated based on data from DLT-evaluable participants during the DLT evaluation period.

    Measured: Up to 90 days after the last dose of treatment

  5. Pharmacokinetics: Serum concentrations of PF-08634404

    Measured: Up to 37 days after the last dose of treatment

  6. Incidence of antidrug antibody against PF-08634404

    Measured: Up to 37 days after the last dose of treatment

  7. Phase 2: Overall Survival

    Overall survival defined as the time from the date of randomization to the date of death due to any cause.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  8. Phase 3: PFS using RECIST v1.1 as assessed by blinded independent central review (BICR)

    Progression Free Survival (PFS) is defined as the time from the date of randomization to the date of the first documentation of objective PD assessed by BICR per RECIST v1.1, or death due to any cause, whichever occurs first.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  9. Phase 3: Confirmed ORR using RECIST v1.1 as assessed by BICR

    ORR is defined as the proportion of participants in the analysis population having a best overall response (BOR) of confirmed CR or confirmed PR according to RECIST v1.1 as assessed by BICR.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  10. Phase 3: DOR using RECIST v1.1 as assessed by BICR

    The time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of the first documentation of PD as determined by BICR assessment per RECIST v1.1, or death due to any cause, whichever occurs first.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  11. Phase 3: Mean scores and Change from baseline in the global health status/quality of life (QoL), function, and symptom scores on the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30)

    The EORTC QLQ-C30 is a questionnaire for quantitative measure of health-related quality of life pertinent to participants with a broad range of cancers who are participating in international clinical trials.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  12. Phase 3: Mean scores and Change from Baseline on the EORTC Quality of Life Cancer Questionnaire - Lung Cancer 13 (EORTC QLQ-LC13)

    EORTC QLQ-LC13 is a lung cancer specific module that serves as an additional 13 item questionnaire to the general EORTC cancer questionnaire, the EORTC QLQ-C30.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  13. Phase 3: Time to definitive deterioration (TTdD) in the global health status/QoL, function, and symptom scores on the EORTC QLQ-C30

    TTdD is defined as the time from date of randomization to first onset of Patient Reported Outcome (PRO) deterioration without subsequent recovery.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

  14. Phase 3: TTdD in the dyspnea, cough, and chest pain scores on the EORTC QLQ-LC13

    TTdD is defined as the time from date of randomization to first onset of Patient Reported Outcome (PRO) deterioration without subsequent recovery.

    Measured: Up to approximately 2 years after completion of study treatment of last study participant

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted12 Nov 2025
  2. Study start9 Dec 2025
  3. Primary completion14 Jun 2030 (estimated)
  4. Study completion11 Mar 2034 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2/3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
550 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07226999
Sponsor's protocol ID
C6461004
Other IDs
2025-523522-41-00, Symbiotic-Lung-04, 2025
Status last verified
Oct 2026
First submitted
7 Nov 2025
Last updated
8 Oct 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Questions about this trial

What is this clinical trial studying?

A Phase 2/3 study testing PF-08634404, Atezolizumab and Chemotherapy in people with Small Cell Lung Cancer (SCLC), run by Pfizer at 82 sites in 10 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 8 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 82 sites in United States, Spain, Puerto Rico, Italy, Japan and 5 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Phase 2: Confirmed Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors version 1.1 [RECIST 1.1] based on the investigator's assessment (time frame: Up to approximately 2 years after completion of study treatment of last study participant). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07226999.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Oct 2026.

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