Docetaxel, Carboplatin, and Rucaparib Camsylate in Treating Patients With Metastatic Castration Resistant Prostate Cancer With Homologous Recombination DNA Repair Deficiency

PRIMARY OBJECTIVES:

I. To determine radiographic progression free survival with 4 cycles of docetaxel with
carboplatin followed by maintenance rucaparib camsylate (rucaparib) in the treatment of
patients with metastatic castration resistant prostate cancer with homologous recombination
DNA repair deficiency.

SECONDARY OBJECTIVES:

I. To assess maximal prostate-specific antigen (PSA) response to induction docetaxel and
carboplatin.

II. To assess PSA response to switch maintenance with rucaparib. III. To assess PSA response
duration to docetaxel and carboplatin followed by switch maintenance with rucaparib.

IV. To assess response of measurable disease.

OUTLINE:

INDUCTION: Patients receive docetaxel intravenously (IV) and carboplatin IV on day 1.
Treatment repeats every 21 days for 4 courses in the absence of disease progression or
unacceptable toxicity.

MAINTENANCE: Patients receive rucaparib camsylate orally (PO) twice daily (BID) on days 1-28.
Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed up periodically.

Inclusion Criteria:

- Signed informed consent form (ICF) providing agreement to adhere to the dosing
schedule, report for all trial visits and authorization, use and release of health and
research trial information

- Histologically or cytologically confirmed adenocarcinoma of the prostate (excluding
predominant small cell histology)

- Ongoing gonadal androgen deprivation therapy with gonadotropin-releasing hormone
(GnRH) analogues, antagonists or orchiectomy; patients who have not had an orchiectomy
must be maintained on effective GnRH analogue/antagonist therapy

- Castration resistant prostate cancer as defined by serum testosterone < 50 ng/ml and
PSA level of at least 2 ng/ml that has risen on at least 2 successive occasions at
least 1 week apart

- Presence of metastatic disease on bone or computed tomography (CT) scan

- Evaluable disease progression by modified RECIST 1.1 (Response Evaluation
Criteria in Solid Tumors)

- Bone disease on bone scan

- Prior therapy with sipuleucel-T, abiraterone, enzalutamide, docetaxel, and/or
cabazitaxel; there is no limit to the number of prior treatment regimens, so long as
prior therapy does not include platinum chemotherapy or a PARP inhibitor

- Eastern Cooperative Oncology Group (ECOG) performance status of =< 1

- Life expectancy >= 12 weeks

- No prior malignancy is allowed except:

- Adequately treated basal cell or squamous cell skin cancer or

- In situ carcinoma of any site or

- Other adequately treated malignancy for which the patient has been disease-free
for at least one year (any prior chemotherapy is allowed)

- Documented evidence of at least ONE or MORE of the following:

* Pathogenic mutation or inactivating alteration of a gene involved in homologous
recombination repair in the tumor

- Note, that if this alteration is identified in a circulating tumor
deoxyribonucleic acid (ctDNA) assay, the variant-allele fraction must be > 20% to
indicate relevance to predominant tumor clone

- Mutation in one or more other genes involved in homologous DNA recombination
repair in the tumor may be included at investigator's discretion

- Homologous recombination repair deficiency by genomic signature in the tumor
by BROCA-HR, Foundation One or equivalent assay

- Presence of pathogenic or likely pathogenic germline mutation/variant in
BRCA2, BRCA1, ATM or PALB2

- Note: Germline mutations in other HR genes will be considered at investigator's
discretion)

- Absolute neutrophil count (ANC) >= 1.5 x 10^9/L (within 14 days of first dose of study
drug)

- Platelets > 100 x 10^9/L (within 14 days of first dose of study drug)

- Hemoglobin >= 9 g/dL (within 14 days of first dose of study drug)

- Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) =< 3 x ULN; if
liver metastases, then =< 5 x ULN (within 14 days of first dose of study drug)

- Bilirubin =< 1.5 x ULN (< 2 x ULN if hyperbilirubinemia is due to Gilbert's syndrome)
(within 14 days of first dose of study drug)

- Serum creatinine =< 1.5 x ULN or estimated glomerular filtration rate (GFR) >= 45
mL/min using the Cockcroft Gault formula (within 14 days of first dose of study drug)

Exclusion Criteria:

- Currently receiving active therapy for other neoplastic disorders

- Symptomatic and/or untreated central nervous system (CNS) metastases; patients with
asymptomatic previously treated CNS metastases are eligible provided they have been
clinically stable for at least 4 weeks

- Known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome
(AIDS)-related illness, active or symptomatic viral hepatitis or chronic liver disease

- Clinically significant heart disease as evidenced by myocardial infarction, or
arterial thrombotic events in the past 6 months, severe or unstable angina, or New
York Heart Association (NYHA) class II-IV heart disease or cardiac ejection fraction
measurement of < 35 % at baseline

- Treatment with an investigational therapeutic drug within 30 days of cycle 1

- Prior therapy with a PARP inhibitor (e.g., olaparib, talazoparib, veliparib,
niraparib, rucaparib)

- Prior therapy with a platinum chemotherapy (e.g. cisplatin, carboplatin, oxaliplatin)

- Active, ongoing toxicity (Common Terminology Criteria for Adverse Events [CTCAE] grade
2 or higher) from prior therapy

- Presence of dementia, psychiatric illness, and/or social situations limiting
compliance with study requirements or understanding and/or giving of informed consent

- Pre-existing duodenal stent and/ or any gastrointestinal disorder or defect that
would, in the opinion of the Investigator, interfere with absorption of rucaparib

- Any condition(s), medical or otherwise, which, in the opinion of the investigators,
would jeopardize either the patient or the integrity of the data obtained