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A study of PF-08634404 and a drug combination for adult patients with extensive-stage small cell lung cancer

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on individuals with Extensive-Stage Small Cell Lung Cancer, a type of lung cancer that has spread to other parts of the body. The purpose of the study is to evaluate how well a new experimental medicine, PF-08634404, works when used together with chemotherapy, which is a type of treatment that uses powerful drugs to kill cancer cells. In this study, the experimental combination includes PF-08634404 along with etoposide and carboplatin. These medications are administered through intravenous infusion, meaning they are delivered directly into a vein.

Participants in the study may receive different treatment paths. One group will receive the combination of PF-08634404 and chemotherapy. Another group will receive a comparison treatment consisting of atezolizumab and chemotherapy. This comparison is used to see if the new experimental combination is more effective at helping people live longer, which is referred to as overall survival. The study will monitor how the body responds to the treatments and track any side effects that may occur during the course of the medical care.

The research process

The trial runs in 2 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Study participation and treatment assignment

    Participation in this study involves being assigned to one of two different treatment groups to compare how well they work for extensive-stage small cell lung cancer, which is an advanced type of lung cancer.

    One group receives an experimental treatment consisting of a combination of pf-08634404 (administered as an intravenous infusion, which is a liquid medicine delivered into a vein) and chemotherapy. the chemotherapy includes etoposide, given by intravenous infusion at a dose of 0 mg/m2, and carboplatin, given by intravenous infusion at a dose of 0 mg.

    The other group receives a comparison treatment consisting of atezolizumab, given by intravenous infusion at a dose of 1200 mg, combined with chemotherapy.

  2. Step 2

    Monitoring and evaluation

    During the study, medical evaluations are performed to check how the body responds to the medications and to monitor safety.

    Checks include measuring tumor response, which looks at whether the cancer has changed in size, and monitoring for adverse events, which are any side effects or health problems that occur during the study.

    Regular laboratory tests are conducted to monitor blood and bodily functions, and assessments are made regarding overall survival and progression-free survival, which tracks how long the disease stays stable without getting worse.

Who can join the trial?

12 criteria

  • You must be 18 years of age or older or meet the legal age for providing consent in your area.
  • People who are able to become pregnant must have a negative pregnancy test (a blood test showing no pregnancy) within 72 hours before receiving the first dose of the study medicine.
  • You must have a confirmed diagnosis of extensive-stage small cell lung cancer, which is a type of lung cancer that has spread widely. This diagnosis must be confirmed using specific medical staging systems that describe the size and location of the cancer.
  • You cannot have a history of non-small cell lung cancer that has changed into small cell lung cancer due to specific genetic mutations.
  • You must not have received systemic therapy (medicine that travels through the entire body, such as chemotherapy) for your extensive-stage small cell lung cancer before joining the study.
  • If you previously had limited-stage small cell lung cancer (cancer that is in a smaller area), you must have finished all treatments for it at least 6 months ago.
  • You must have at least one measurable lesion, which is a tumor or area of cancer that is large enough to be clearly seen and measured on medical imaging scans.
  • You must have enough tumor tissue available from a recent biopsy (a procedure where a small sample of tissue is removed) for testing. This tissue must be provided in a specific format, such as a wax-embedded block or slides.
  • You must have an ECOG performance status of 0 or 1, which is a scale used by doctors to measure how well you can perform daily activities and your overall level of physical functioning.
  • You must have a life expectancy of more than 12 weeks.
  • You must have adequate organ function, meaning your blood counts and organs like your heart, liver, and kidneys are working well enough.
  • You must be able to provide written informed consent, which is a signed document stating that you understand the study and agree to participate.

Who cannot join the trial?

26 criteria

  • People with active cancer spreading to the central nervous system, which includes the brainstem, the protective layers around the brain and spinal cord (meninges), or the spinal cord itself.
  • People with brain metastases (cancer that has spread to the brain) that have not been stable for at least 14 days after treatment or who have needed steroids (strong anti-inflammatory medicine) for symptoms in the last 7 days.
  • People with a QTcF interval (a measurement of the heart's electrical timing) greater than 480 msec on an ECG (a test that records the heart's electrical activity).
  • People who have had major surgery or severe injury within 4 weeks, or who have a major surgery planned during the study.
  • People who have had minor surgery (not including certain types of central line placements) within 3 days and have not fully recovered.
  • People with fluid buildup in the lungs (pleural effusion), around the heart (pericardial effusion), or in the abdomen (ascites) that causes symptoms or requires regular drainage.
  • People with a history of severe bleeding issues, such as gastrointestinal bleeding (bleeding in the stomach or intestines), hemoptysis (coughing up blood), or epistaxis (nosebleeds), within 1 month.
  • People with certain stomach or intestinal issues within 6 months, such as esophageal varices (swollen veins in the food pipe), ulcers, perforation (a hole in the digestive tract), fistula (an abnormal connection between organs), or obstruction (a blockage).
  • People with active infections, such as those caused by viruses, bacteria, or fungi, that require systemic antimicrobial treatment (medicine that travels through the whole body to fight infection).
  • People with HIV, unless the infection is well-controlled with ART (medicine used to treat HIV) and certain blood counts are stable.
  • People who test positive for HBV (Hepatitis B) or have an active HCV (Hepatitis C) infection.
  • People with an active TB (tuberculosis) infection or suspected infection.
  • People with a history of immunodeficiency (a weakened immune system).
  • People who have had a severe allergic reaction, such as anaphylaxis (a life-threatening allergic reaction), to any of the study medicines.
  • People with certain mental health conditions, including suicidal ideation (thoughts of suicide) in the past year or suicidal behavior in the past 5 years.
  • People with leptomeningeal disease (cancer that spreads to the fluid and membranes surrounding the brain and spinal cord).
  • People at high risk of hemorrhage (severe bleeding) due to tumor growth or tumor invasion into critical organs like the heart, aorta, or windpipe.
  • People who have had another type of cancer within the last 3 years, unless it was a low-risk type like certain skin cancers.
  • People who still have toxicities (harmful side effects) from previous cancer treatments that have not improved to a safe level.
  • People who have had an allogeneic organ transplant (receiving an organ from another person) or a stem cell transplant from another person.
  • People with active autoimmune diseases (conditions where the immune system attacks the body) that required systemic medicine in the last 2 years.
  • People with certain lung conditions, such as ILD or pneumonitis (inflammation of the lung tissue), or those with low DLCO (a measure of how well the lungs transfer gas into the blood).
  • People with severe lung diseases like COPD (chronic obstructive pulmonary disease) or a recent pulmonary emboli (blood clot in the lung).
  • People with uncontrolled heart problems, such as unstable angina (chest pain), myocardial infarction (heart attack), or arrhythmia (irregular heartbeat).
  • People with uncontrolled hypertension (high blood pressure) or diabetes (high blood sugar).
  • People with uncontrolled hypercalcemia (too much calcium in the blood).
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Investigated drugs

  • Etoposide

    is a type of chemotherapy drug used to treat cancer by stopping the growth and division of cancer cells.

  • Atezolizumab

    is an immunotherapy drug that helps the body's own immune system recognize and attack cancer cells.

  • PF-08634404

    is an experimental drug being studied to see if it can help fight cancer when used alongside chemotherapy.

  • Carboplatin

    is a chemotherapy drug used to kill cancer cells by interfering with their ability to copy their DNA.

What is already known about the treatment

  • Etoposide

    This medication is an anticancer drug administered through an intravenous injection into a vein. It is widely used in standard medical practice to treat various types of cancer, including small cell lung cancer. The drug works by interfering with the way cancer cells copy their DNA, which prevents them from growing and multiplying. It belongs to a group of medicines known as topoisomerase inhibitors.

  • Atezolizumab

    This is an immunotherapy drug that is given to patients through an intravenous infusion. It is an established treatment used to help the body's immune system fight certain types of cancer. The drug works by blocking a specific protein on immune cells that cancer cells often use to hide from the body's natural defenses. It is classified as a checkpoint inhibitor.

  • PF-08634404

    This experimental drug is provided as a concentrate for infusion and is administered directly into a vein. It is currently being studied in clinical trials to determine its effectiveness in treating advanced lung cancer. The medication works at a molecular level to disrupt specific biological processes that allow cancer cells to survive and spread. It is categorized as a targeted therapy under investigation.

  • Carboplatin

    This is a chemotherapy medication that is delivered to the patient through an intravenous infusion. It is a common and well-known treatment used to manage many different types of cancer. The drug works by attaching itself to the DNA of cancer cells, which damages their genetic material and stops them from dividing. It belongs to a class of drugs called platinum-based antineoplastic agents.

Investigated diseases

Extensive-Stage Small Cell Lung Cancer - This is a type of cancer that begins in the cells of the lungs. It is characterized by the rapid growth and spread of abnormal cells. In the extensive stage, the cancer has moved beyond the primary site in the lung to other parts of the body or to lymph nodes. The disease progresses as these cancerous cells multiply and travel through the bloodstream or lymphatic system. This spread can affect various organs throughout the body.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2025-523522-41-00Protocol codeC6461004Estimated enrolment540 patientsSponsorPfizer Inc.

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