Promising combo trial for prostate cancer halted early

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adenocarcinoma of the prostate that is metastatic or unresectable and for which standard curative options do not exist * Radiographic evidence of metastatic prostate cancer * Progressive disease despite ongoing androgen deprivation therapy (ADT), defined as castration resistant prostate cancer (CRPC) * Other than ongoing prior treatment with other hormonal agents such as antiandrogens or ketoconazole must have been stopped at least two weeks prior to enrollment * Have received prior docetaxel-based chemotherapy for prostate cancer within the past 12 months. Such chemotherapy must have been stopped at least 3 weeks prior to the first dosing in this study * Life expectancy of at least 12 weeks * Must agree to use adequate contraception prior to study entry and for the duration of study participation Exclusion Criteria: * Prior treatment with enzalutamide, TOK-001, or ARN-509 * Participants who have received more than two prior chemotherapy regimens for metastatic CRPC * Receiving any other investigational anticancer agents * Known brain metastases * History of allergic reactions attributed to compounds of similar chemical or biologic composition to tivozanib or enzalutamide * Radiotherapy or minor surgical procedure within 2 weeks, or major surgical procedure within 4 weeks prior to administration of first dose of study drug; inadequate recovery from prior surgical procedure * History of seizure of condition that may predispose to seizure * Significant cardiovascular disease * Non-healing wound, bone fracture or skin ulcer * Active peptic ulcer disease, inflammatory bowel disease, ulcerative colitis or other gastrointestinal condition with increased risk of perforation; history of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within 4 weeks prior to administration of first dose of study drug * Serious/active infection or infection requiring parenteral antibiotics * Significant thromboembolic or vascular disorders within 6 months prior to administration of first dose of study drug * Currently active second primary malignancy, including hematologic malignancies, except for non-melanoma skin cancers, in situ cervical cancer, and ductal or lobular carcinoma in situ of the breast * History of genetic or acquired immune suppression disease such as HIV; subjects on immune suppressive therapy for organ transplant * Inability to swallow capsules, malabsorption syndrome or gastrointestinal disease that severly affects the absorption of study drugs, major resection of the stomach or small bowel, or gastric bypass procedure * Significant bleeding disorders within 6 months prior to administration of first dose of study drug * Psychiatric disorder or altered mental status precluding informed consent or protocol-related testing