Clinical efficacy of combination therapies with androgen receptor antagonists for treatment of multiple refractory cancers.

Abstract

115 Background: Androgen Receptor (AR) antagonists have been the mainstay of prostate cancer treatments. However, there is increasing interest in the use of anti-AR agents in treatment of other cancers such as Triple Negative Breast Cancer and Lung Cancer. AR antagonists are usually administered as single agents and rarely in combination with other cytotoxic or targeted agents. We hypothesized that administration of AR antagonists indicated by Encyclopedic Tumor Analysis (ETA) in synergistic combination with cytotoxic, targeted or other endocrine agents may afford clinical benefit for refractory cancers. Methods: We evaluated treatment response in a basket of 18 patients with various advanced refractory solid organ malignancies, who received personalized treatments based on ETA investigations. As part of ETA, freshly biopsied tumor tissue and blood samples were evaluated for various markers such as gene mutations (DNA), gene expression (RNA) and receptor proteins (immunohistochemistry). Finally, viable tumor cells from the freshly biopsied tissue were used in in vitro chemosensitivity analysis with a panel of cytotoxic and targeted therapy agents. Radiological disease status was evaluated retrospectively and treatment response as well as Progression Free Survival (PFS) was determined. Results: Among the 18 patients, there were 8 males (44%) and 10 females (56%) with median age of 58 years (range 28 – 79). Patients had received a median of 3 prior lines of treatment (range 1 – 14). All 18 patients received ETA guided combination treatments which included an AR blockade. 9 patients showed Partial Response ( PR) with an Objective Response Rate (ORR) of 50%. 5 patients (28%) showed stable disease for ≥3 months (Clinical Benefit Rate = 77.8%), while 4 patients (22%) showed disease progression. In 2 patients (11%) disease progressed at ~60 days and in the remaining 2 patients (11%) progression was seen at > 120 days. Treatments were well tolerated without severe adverse events. Conclusions: Androgen addicted, refractory solid organ tumors respond to combinations of cytotoxic, targeted and endocrine agents along with AR antagonists guided by ETA.