Recruiting
Phase 1

Mevrometostat

Sponsor:

Pfizer

Code:

NCT03460977

Conditions

Metastatic Castration Resistant Prostate Cancer (mCRPC)

Small Cell Lung Cancer (SCLC)

Follicular Lymphoma (FL)

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

Mervometostat (PF-06821497)

Enzalutamide

Itraconazole

Study Details

Brief summary:

The purpose of this study is to learn about the safety and effects of the study medicine (called Mevrometostat) for the possible treatment of Relapsed/ Refractory Small Cell Lung Cancer (SCLC), Castration Resistant Prostate Cancer (CRPC) and Follicular Lymphoma (FL). The study consists of 3 parts; Part 1 and 2 enrolled participants with SCLC, metastatic CRPC, and FL are closed for enrollment.

Part 3, which is open for enrollment is seeking men who:

  • have Castration Resistant Prostate Cancer (CRPC) and
  • have previously received treatment for CRPC and have progressed from the last treatment

All participants in Part 3 of this study will receive mevrometostat and/ or enzalutamide. Part 3 consists of 2 sub studies each has an assessment phase and a maintenance phase. The Part 3 DDI substudy consist of 2 cohorts, Cohort 1 (monotherapy cohort) and Cohort 2 (Combination cohort).

In the assessment phase:

  • participants in the BE substudy will take 3 single doses of mevrometostat by mouth over 3 periods.
  • participants in the DDI substudy Cohort 1 (monotherapy cohort) will take mevrometostat 2 times a day and/or itraconazole 1 time a day based on a present schedule.
  • participants in the DDI substudy Cohort 2 (combination cohort) will take mevrometostat 2 times a day, enzalutamide 1 time a day, and/or itraconazole 1 time a day based on a present schedule.

After completion of the assessment phase, participants will enter the maintenance phase where they will receive mevrometostat 2 times a day and enzalutamide 1 time a day by mouth until their cancer is no longer responding.

The study will look at the experiences of participanrs receiving the study medicine. This will help see if the study medicine is safe and effective.

Conditions

Metastatic Castration Resistant Prostate Cancer (mCRPC)

Small Cell Lung Cancer (SCLC)

Follicular Lymphoma (FL)

Study ID

NCT03460977

Start date

Apr 17, 2018

Status verified date

Aug, 2026

Completion date

Jul 7, 2029

Anticipated

Primary completion date

Apr 20, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Part 1 and Part 2 (Closed for enrollment).

Part 3 Key Inclusion Criteria:

  • Histological or cytological diagnosis of castration resistant prostate cancer.
  • Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0-2 with expected life expectancy of at least 6 months.
  • Adequate bone marrow, renal, and liver function

Part 3 Key Exclusion Criteria:

  • Prior irradiation to >25% of the bone marrow.
  • QTcF interval >480 msec at screening.
  • Hypertension that cannot be controlled by medications (>150/90 mmHg despite optimal medical therapy).
  • Known or suspected hypersensitivity to PF 06821497 or any components or enzalutamide (CRPC)
  • Active inflammatory gastrointestinal disease, chronic diarrhea, known diverticular disease or previous gastric resection or lap band surgery.
  • Current use or anticipated need for food or drugs that are known strong and moderate CYP3A4/5 inducers or inhibitors
  • Prior enzalutamide within the last 4 weeks
  • DDI SUBSTUDY:
  • history of CHF or evidence of ventricular dysfunction
  • fructose intolerance
  • coadministration of CYP3A4 substrates

Study Design

Enrollment

453 participants

Anticipated

Allocation

Non randomized

Intervention Model

Sequential

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Dose Escalation (Part 1A)

Participants with SCLC, CRPC and FL will receive mevrometostat at escalating dose levels

experimental: Dose Escalation (Part 1B)

Participants with FL will receive mevrometostat at escalating dose levels

experimental: Dose Escalation (Part 1C)

Participants with mCRPC will receive mevrometostat at escalating dose levels.

experimental: Dose Escalation (Part 2A)

Participants with mCRPC and SCLC will receive mevrometostat at escalating dose levels in combination with SOC.

experimental: Dose Expansion (Part 2B)

Participants with CRPC will receive mevrometostat in combination with SOC or SOC alone.

experimental: Japan Cohort

Participants with CRPC will receive mevrometostat at one or two doses

experimental: China cohort

Participants will receive mevrometostat at one or two doses

experimental: Dose Expansion (Part 2C)

Participants with mCRPC will receive mevrometostat at a different dose/dosing regimen than that of Part 2B in combination with SOC

experimental: BE Substudy

In the assessment phase, each enrolled participant will receive single doses of the 2 different mevrometostat formulations in 3 periods with alternating dosing and washout between each dose. In the maintenance phase, each participant will receive mevrometostat 2 times a day and enzalutamide 1 time a day.

experimental: DDI Substudy

The DDI substudy assessment phase will consist of 2 Cohorts, Cohort 1 (monotherapy cohort) and Cohort 2 (combination cohort). In the Cohort 1 assessment phase, each enrolled participant will receive a combination of mevrometostat and itraconazole based on preset schedule. In the Cohort 2 assessment phase, each enrolled participant will receive a combination of mevrometostat, enzalutamide, and itraconazole based on preset schedule. In the maintenance phase, each participant will receive mevrometostat 2 times a day and enzalutamide 1 time a day.

Interventions

Mervometostat (PF-06821497)

Oral continuous

Enzalutamide

Oral continuous

Itraconazole

Oral solution

Primary outcome measure

  • Percentage of patients with dose limiting toxicities (DLTs) to determine the maximum tolerated dose (MTD) [ Time Frame: Baseline up to 90 days ]
  • Overall safety profile including adverse events [ Time Frame: Baseline up to approximately 2 years ]
  • Preliminary efficacy determination as evaluated by disease specific response criteria [ Time Frame: Through study completion, approximately 2 years past last patient first visit. ]
  • Overall safety profile including laboratory abnormalities [ Time Frame: Baseline up to approximately 2 years ]
  • Overall safety profile including vital signs [ Time Frame: Baseline up to approximately 2 years ]
  • Evaluate time to event mevrometostat and enzalutamide vs enzalutamide alone including radiographic prgression free survival [ Time Frame: Baseline until disease progression or death or through study completion (approx 2 years) ]

Central Contacts and Locations

Central contacts

Pfizer CT.gov Call Center

1-800-718-1021ClinicalTrials.gov_Inquiries@pfizer.com

Locations

Oncology Hematology West, PC dba Nebraska Cancer Specialists

Recruiting

Omaha, Nebraska, United States, 68130

OU Health University of Oklahoma Medical Center

Recruiting

Oklahoma City, Oklahoma, United States, 73104

Stephenson Cancer Center (chemo location)

Recruiting

Oklahoma City, Oklahoma, United States, 73104

Carolina Urologic Research Center

Recruiting

Myrtle Beach, South Carolina, United States, 29572

Parkway Surgery Center

Recruiting

Myrtle Beach, South Carolina, United States, 29572

Sarah Cannon Research Institute - Pharmacy

Recruiting

Nashville, Tennessee, United States, 37203

SCRI Oncology Partners

Recruiting

Nashville, Tennessee, United States, 37203

NEXT Dallas

Recruiting

Irving, Texas, United States, 75039

NEXT Oncology

Recruiting

San Antonio, Texas, United States, 78229

More Information

Sponsor

Pfizer

Last update posted

Aug 24, 2026

Last verified

Aug, 2026

Keywords

  • EZH2
  • enhancer of zeste homolog 2
  • castrate resistant prostate cancer
  • prostatecancer-study.com
  • mCRPC
  • efficacy
  • safety
  • pharmacokinetics
  • pharmacodynamics
  • dose escalation
  • dose expansion
  • open-label
  • small cell lung cancer
  • SCLC
  • follicular lymphoma
  • FL
  • relapsed
  • refractory

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Pfizer on 2026-08-24.