Mevrometostat Treatment of Relapsed/Refractory SCLC, Castration Resistant Prostate Cancer, and Follicular Lymphoma

Key Inclusion Criteria:

Histological or cytological diagnosis of advanced / metastatic solid tumor with the following tumor types in individual study parts:

Part 1A (closed to enrollment):

Part 1B (closed to enrollment):

Part 1C:

• Metastatic Castration resistant prostate cancer. Patients should have receivedeither abiraterone and/or enzalutamide treatment and have evidence of prostatecancer progression (per PCWG3) Japan cohort

• Castration resistant prostate cancer that is resistant to SOC or for which no localregulatory approved SOC is available that would confer significant clinical benefitin the medical judgement of the investigator. Patients should have received eitherabiraterone and/or enzalutamide treatment and have evidence of prostate cancerprogression (per PCWG3) China cohort

• Castration resistant prostate cancer that is intolerant/resistant to SOC or forwhich no local regulatory approved SOC is available that would confer significantclinical benefit in the medical judgement of the investigator. Patients who refusedSOC may be eligible. Patients should have received either abiraterone and/orenzalutamide treatment and have evidence of prostate cancer progression (per PCWG3)

Part 2A:

• Metastatic Castration resistant prostate cancer. Patients should have received either abiraterone and/or enzalutamide treatment, may have received up to 1 line of chemotherapy and have evidence of prostate cancer progression (per PCWG3)

Part 2B/2C:

• Metastatic Castration resistant prostate cancer. Patients should have receivedabiraterone treatment, may have received up to 1 prior line of chemotherapy, havenot received prior enzalutamide, apalutamide or darolutamide and have evidence ofprostate cancer progression (per PCWG3)

• Patients must have radiographic evidence of disease

Other inclusion criteria:

-Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0 or 1.

Key Exclusion Criteria:

• Prior Chemotherapy: Part 1C , Japan cohort and China cohort (CRPC): no more than 2previous regimens of chemotherapy Part 2A: mCRPC: no more than 1 previous regimen ofsystemic chemotherapy Part 2B (mCRPC): no more than 1 previous regimen ofchemotherapy

• 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 optimalmedical therapy).

• Known or suspected hypersensitivity to PF 06821497 or any components or enzalutamide (CRPC)

• Active inflammatory gastrointestinal disease, chronic diarrhea, known diverticulardisease or previous gastric resection or lap band surgery. Gastroesophageal refluxdisease under treatment with proton pump inhibitors is allowed.

• Current use or anticipated need for food or drugs that are known strong CYP3A4/5inducers or inhibitors, including their administration within 10 days or 5 halflives of the CYP3A4/5 inhibitor, whichever is longer prior to first dose ofinvestigational product.