Primary objective: To assess the early signals for anti-tumor activity (i.e. objective response rate, progression-free survival) of pembrolizumab in combination with vorinostat in patients with advanced prostate, renal or urothelial cell carcinoma.

Secondary objectives: (1) To evaluate the overall safety profile of pembrolizumab in combination with vorinostat; (2) To assess the safety and tolerability of pembrolizumab in combination with vorinostat in patients with advanced prostate, renal or urothelial cell carcinoma in order to select the recommended Phase 2 Dose (RP2D)

This is a Phase I/Ib, open-label, safety, and pharmacodynamics study of pembrolizumab in combination with vorinostat in patients with advanced prostrate, renal or urothelial cell carcinoma. This clinical study will be composed of a Dose Finding Phase and an Expansion Phase. The Dose Finding Phase will estimate the Recommended Phase II Dose (RP2D) in patients with advanced renal and urothelial cell carcinoma patients. The Dose Finding Phase will lead to the identification of an Expansion Test Dose for pembrolizumab in combination with vorinostat. The Expansion Test Dose will be the Recommended Phase II Dose (RP2D) (i.e. the highest tested dose that is declared safe and tolerable by the Investigators and Sponsor). Patients will be treated with oral vorinostat every day for 14 days, and with pembrolizumab at the fixed dose of 200 mg IV. Each cycle is every 21 days. Two dose levels of vorinostat will be tested in 2-patient cohorts according to the 3 + 3 standard design (100 mg and 200 mg). 200 mg dose represents 50% of the recommended vorinostat dose as single agent.

For the Dose Finding Phase (Combination Phase), the starting dose level of vorinostat will be 100 mg by mouth (PO) every day for 14 days, with 7 days break. The first dose level will have a minimum of 3 patients treated (unless the first 2 patients experience dose-limiting toxicities (DLTs) before the 3rd patient is enrolled).

Once the RP2D is identified, the Dose Expansion Phase will be opened. During the Dose Expansion Phase, the study will have a run-in phase with sequential single-agents and then the combination phase. The run-in phase may be waived at the investigator's discretion. The reason for the run-in phase during dose expansion is to obtain data on the immunomodulatory effects of vorinostat separately from pembrolizumab. Forty-five patients with prior treatments will be enrolled in three expansion cohorts: 15 anti-PD1 naive renal and urothelial patients 15 anti-PD1 resistant renal and urothelial patients (defined as patients with transient clinical response or without clinical response to prior immune-checkpoint inhibition), and 15 patients with androgen-sensitive or castration-resistant prostate cancer. The prostate cohort has been added in an amendment during the Dose Expansion Phase, and therefore, will not be part of the Dose Finding Phase.

Subject Inclusion Criteria

In order to be eligible for participation in this trial, the subject must:

1. Have one of the following diagnoses/conditions:

   1. Renal cell carcinoma - previously treated and progressive disease, locally advanced or metastatic
   2. Urothelial cell carcinoma - previously treated and progressive disease, locally advanced or metastatic
   3. Prostate cell carcinoma - progressive disease, locally advanced or metastatic disease (enrolling only at IUSCC and its affiliates). Patients with hormone-sensitive disease where ADT in combination with either docetaxel or abiraterone is indicated will not be eligible (i.e. patients with high burden disease).

2. Be willing and able to provide written informed consent for the trial.

3. Be 18 years of age or older on day of signing informed consent.

4. Have measurable disease based on RECIST 1.1. for patients with solid malignancies or evaluable disease as assessed by bone scan and/or PET scan. Patients with advanced or metastatic prostate cancer can have either androgen-sensitive or castration-resistant disease.

5. Have a performance status of 0-2 on the ECOG Performance Scale.

6. Demonstrate adequate organ function. All screening labs should be performed within 10 days of treatment initiation.

7. Female subject of childbearing potential should have a negative urine or serum pregnancy test within 72 hours prior to receiving the first dose of study medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required.

8. Subjects of childbearing potential should be willing to use 2 methods of contraception for the course of the study through 120 days after the last dose of study medication. Acceptable methods of birth control include: abstinence, partner with previous vasectomy, placement of an intrauterine device (IUD), condom with spermicidal foam/gel/film/cream/suppository, diaphragm or cervical vault cap, or hormonal birth control (pills or injections). NOTE: Females are considered of childbearing potential unless they are surgically sterile (they have undergone a hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or they are postmenopausal (a woman who is ≥45 years of age and has not had menses for greater than 1 year).

9. Male subjects without a previous vasectomy should agree to use an adequate method of contraception (i.e. abstinence, condom with spermicidal foam/gel/film/cream) starting with the first dose of study therapy through 120 days after the last dose of study therapy.

10. Subjects with urothelial carcinoma must have received a prior platinum-based regimen in the metastatic setting or have signed consent for this study within 12 months of receiving a platinum-based regimen in the perioperative setting (neoadjuvant or adjuvant).

11. Subjects with a history of diabetes mellitus must have HgbA1c level of <8.5% upon study entry.

Subject Exclusion Criteria

The subject must be excluded from participating in the trial if the subject:

1. Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the first dose of treatment.

2. Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of trial treatment.

3. Has active TB (Bacillus Tuberculosis)

4. Hypersensitivity to pembrolizumab or any of its excipients.

5. Has had a prior anti-cancer monoclonal antibody (mAb) within 4 weeks prior to Cycle 1 Day 1 or who has not recovered (i.e. ≤ Grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier.

6. Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to Cycle 1 Day 1 or who has not recovered (i.e. ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent.

   • Note: Subjects with ≤ Grade 2 neuropathy are an exception to this criterion and may qualify for the study.
   • Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.

7. Has a known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer.

8. Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis. Subjects with previously treated brain metastases may participate provided they are stable (without evidence of progression by imaging for at least four weeks prior to the first dose of trial treatment and any neurologic symptoms have returned to baseline), have no evidence of new or enlarging brain metastases, and are not using steroids for at least 7 days prior to trial treatment. This exception does not include carcinomatous meningitis which is excluded regardless of clinical stability.

9. Has active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (e.g. thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.

10. Has known history of, or any evidence of active, non-infectious pneumonitis.

11. Has an active infection requiring systemic therapy.

12. Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject's participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.

13. Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.

14. Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the pre-screening or screening visit through 120 days after the last dose of trial treatment.

15. Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent (only during Dose Expansion Phase Cohort A).

16. Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies).

17. Has known active Hepatitis B (e.g. HBsAg reactive) or Hepatitis C (e.g. HCV RNA [qualitative] is detected).

18. Has received a live vaccine within 30 days of planned start of study therapy.