Citations

143 Background: Systemic treatment in the management of metastatic prostate cancer is inevitable. However, there is a growing interest in metastases-directed therapy (MDT). We sought to investigate the efficacy of MDT in treating patients with solitary metastatic prostate cancer and hence, delaying initiation of systemic treatment (i.e., Androgen deprivation therapy or chemotherapy). Methods: We retrospectively identified 61 patients treated with targeted therapy in the form of surgery (n = 30), stereotactic body radiation therapy (SBRT) (n = 25), or cryotherapy (n = 7) for their solitary metastases prostate cancer. Complete response was defined by achieving a PSA value of ≤0.2 ng/ml plus resolution of the solitary metastatic lesion on C-11 choline PET choline scan, while incomplete response was defined by a residual PSA of > 0.2 ng/ml and/or radiographic evidence of disease following metastases-targeted therapy. Results: Mean (±SD) age was 68.4 (±7.8) yrs., median (IQR) primary Gleason Score was 7 (7-9) and median (IQR) pre-MDT PSA was 2 (1.3-3.8) ng/ml. Median (IQR) time from primary treatment of the prostate to MDT was 5.1 (2.7-10.1) years. None of the patients were on hormone therapy at the time of presentation with solitary metastases prostate cancer. 30 patients had bone metastases, 29 patients had lymph node metastases, 1 patient had soft tissue metastasis (pelvic metastatic mass), and another patient had visceral metastasis (to the lung). 42% of the patients (n = 26) achieved complete response to targeted therapy. Median time to initiation of 2nd line systemic treatment following MDT was 17.8 months for the complete responders versus 9.3 months for incomplete responders. 11% of the patients (n = 7) did not require 2nd line therapy after their MDT for a mean (±SD) time of 56.9 (±22.5) months. Conclusions: The use of targeted therapy in the management of patients with solitary metastatic disease or low-volume metastatic disease can provide comparable outcomes to those of systemic treatment. Further studies are warranted.

AbstractBackgroundOptimal sequencing of systemic therapy in the management for metastatic castration resistant prostate cancer (mCRPC) remains poorly elucidated. The CHAARTED and STAMPEDE studies have proven that early chemotherapy in the hormone‐sensitive setting yields a greater net survival advantage than docetaxel for mCRPC. In a retrospective study, we attempt to investigate the two most common treatment sequences for mCRPC and investigate whether earlier chemotherapy for mCRPC is consequential to survival outcomes.MethodsWe identified 112 patients with mCRPC treated at the Mayo Clinic between 2011 and 2017. We identified two cohorts, 80 patients (group A) received full course docetaxel chemotherapy followed by second generation hormone therapy (2nd gen androgen deprivation therapy [ADT]; Abiraterone or Enzalutamide) and 32 patients (group B) treated with 2nd gen ADT followed by docetaxel. The primary endpoint evaluated was 3‐year cancer‐specific survival.ResultsMean prostate specific antigen at initiation of first treatment was 32.0 in group A and 21.7 in group B (P = .4). Bone metastases were more prevalent in group B (87% vs 58%, P = .01). All other clinicopathologic variables were statistically similar between group A and group B. Three‐year cancer‐specific survival was 87.4% vs 64.1% for group A and group B, respectively (P = .016). We report a univariate hazard ratio of 3.61 (95% CI, 1.74‐9.5, 0 P = .01). Three‐year overall survival was 82.4% and 60.8% for group A and group B, P = .01. These results held true when excluding patients with lymph node only metastasi.ConclusionOur data indicates that sequence of systemic therapy may influence outcomes for mCRPC and that docetaxel should be considered before 2nd generation ADT. Our results support the importance of earlier chemotherapy in the castration resistant state.

AbstractObjectivesPrevious studies noted discordance of programmed death‐1 (PD‐1) and one of its ligands (PD‐L1) across patient‐matched primary and metastatic clear cell renal cell carcinoma (ccRCC). There are inconsistencies if the primary or metastatic tumor has higher expression, and whether metastatic tumor expression is associated with patient outcome. Thus, we examined PD‐1 and PD‐L1 in patient‐matched tumors using a large number of ccRCC patients with long follow‐up.Materials and MethodsWe analyzed PD‐1 and PD‐L1 using immunohistochemistry in patient‐matched primary and metastatic tumors from 110 ccRCC patients. Concordance was assessed among longitudinal metastatic tumors, as well as across patient‐matched primary and metastatic tumors. Cox proportional hazards regression was used to evaluate the associations of metastatic tumor expression with cancer‐specific survival.ResultsWe observed inter‐metastatic tumor heterogeneity of PD‐1 in 25 (69%) of the 36 patients and of PD‐L1 in seven (19%) patients. Concordance between patient‐matched primary and metastatic tumors was 73% (Kappa = 0.16, 95% CI: −0.003‐0.32). Similarly, concordance of PD‐L1 between metastatic and patient‐matched primary tumors was 78% (Kappa = 0.27, 95% CI: 0.09‐0.46). Both markers demonstrated higher expression in primary vs metastatic tumors. Metastatic tumor expression of PD‐1 was significantly associated with metastatic location (P < .0001) and ccRCC‐specific survival (HR = 2.15, 95% CI: 1.06‐4.36, P = .035).ConclusionsThe expression of PD‐1 and PD‐L1 is discordant across patient‐matched ccRCC tumors, with higher expression in primary tumors. Higher PD‐1 expression was associated with metastatic location and lower cancer‐specific survival. If validated, these results highlight the importance of evaluating these biomarkers in metastatic tissue specifically.

52 Background: Ipi enhances antitumor immunity by blocking cytotoxic T-lymphocyte antigen-4. We recently reported the results of CA184-043, a phase 3 study of post-docetaxel mCRPC with Ipi vs Pbo, following single-dose radiotherapy (RT). While the study did not meet the primary endpoint of improving overall survival (HR=0.85, p=0.053), Ipi demonstrated antitumor activity in other efficacy endpoints, including progression-free survival. The present analyses further characterize the safety profile of Ipi in this study. Methods: Safety was evaluated for all treated patients (pts; N=393 for Ipi 10 mg/kg, N=396 for Pbo) starting from first study dose and ending 70 days after the last study dose, including maintenance dosing. Results: Any grade (Gr) irAEs occurred in 63.4% and 21.7% of pts in the Ipi and Pbo arms, respectively. Most common Gr 3/4 irAEs were gastrointestinal (GI) (18.1%; mostly diarrhea and colitis). Gr 3/4 liver irAEs (4.6%) were mostly elevations in AST or ALT. Other Gr 3/4 irAEs were uncommon: endocrine (2.0%), skin (1.0%), and neurological (0.3%). Among Ipi-treated pts, there were no meaningful differences in the frequency or severity of GI AEs between those who received baseline pelvic RT and those who did not (n=141 vs 252; any Gr 77.3% vs 69.8%; Gr 3/4 25.5% vs 21.8%, respectively). There were 5 GI perforations in the Ipi arm (3 within 70 days of last dose [2 related, 1 unrelated], 2 after 70 days of last dose, both related), and none in the Pbo arm. Deaths due to study drug toxicity, as per the investigators, occurred in 4 pts (4, Ipi and 0, Pbo). Conclusions: In this study of Ipi in mCRPC, the most frequent severe irAEs were diarrhea and colitis. Most irAEs were manageable using established treatment algorithms. Clinical trial information: NCT00861614. [Table: see text]

2 Background: The CA184-043 phase 3 study did not reach statistical significance for its primary endpoint of OS (HR=0.85, p=0.053). However, antitumor activity was observed in other efficacy endpoints, including progression-free survival. Prespecified subset analyses were performed to understand if any prognostic features may identify mCRPC patients (pts) more likely to benefit from Ipi treatment. Methods: 799 pts were randomized to receive a single dose of radiotherapy (RT) followed by either Ipi (N=399) or Pbo (N=400). Prespecified subset analyses based on Kaplan-Meier/Cox methodology were performed using known prognostic factors for OS in mCRPC. Results: Prespecified subset analyses suggested that Ipi may be more active in pts with favorable prognostic factors, including no visceral disease, alkaline phosphatase <1.5 ULN, and hemoglobin ≥11 g/dL (Table). The safety profile in this study was consistent with previous reports of Ipi. Conclusions: Based on these subset analyses, Ipi added to RT appears to have greater activity than RT alone in pts with a favorable prognostic profile. These results support continued investigation of Ipi in the ongoing CA184-095 study in chemotherapy-naive mCRPC pts. Clinical trial information: NCT00861614. [Table: see text]