83 Background: Most prostate cancers are driven by the androgen receptor (AR) and have significant responses to AR inhibition. However, approximately 20-30% respond poorly to AR signaling inhibitors and have an atypical and virulent clinical course. Previous studies have shown that early declines in PSA and CTC on treatment are linked with “AR-responsiveness” in metastatic castration resistant prostate cancer (mCRPC). Few non-androgen directed therapies are approved for AR-unresponsive patients though combination cabazitaxel and carboplatin showed efficacy in this patient population in a phase I/II trial (Corn et al. Lancet Oncol, 2019). We hypothesized that early addition of chemotherapy in AR-unresponsive patients would improve outcomes. Methods: In a modular phase II trial (NCT02703623), men with mCRPC treated with abiraterone acetate plus prednisone and apalutamide were classified at week 8 as having a ‘satisfactory’ decline in PSA (≥ 50% from baseline) and CTC (≤5/7.5mL) or ‘unsatisfactory’. Patients with ‘unsatisfactory’ declines had carboplatin and cabazitaxel added to the AR inhibitors. Primary objectives included the estimation of the overall survival (OS) of patients in this cohort. Results: 198 men were registered. 59 (31.5%) of 187 evaluable had ‘unsatisfactory’ marker declines. Patients were primarily white/non-Hispanic men (81%) over the age of 60 (78%) with ECOG score of 0 (75%). Median baseline PSA and CTC were 11.3 ng/mL and 9.0 cells/mL respectively. Median follow-up was 31.7 months with median OS 19.2 months (95% CI 14.8-27.8). Median TTF was 9.0 months (6.9-11.0). Related adverse events included decreased WBC (39%; 15% G3+), anemia (56%; 7% G3+), and lymphopenia (59%; 8% G3+). There was one grade 5 sepsis of unknown attribution. Conclusions: Although early platinum-based chemotherapy offers a durable response in a subset of AR unresponsive patients, there were patients that continued to have rapid progression. We will present additional clinical and molecular data (IHC, RNA-seq, WES) in an attempt to further differentiate AR responders from AR non-responders. Clinical trial information: NCT02703623.
Chronic thyroiditis in patients with advanced breast carcinoma: metabolic and morphologic changes on PET-CT
