Intensity-Modulated Radiotherapy with Regional Hyperthermia for High-Risk Localized Prostate Carcinoma

Background: The purpose of this study was to evaluate the efficacy and toxicity of adding regional hyperthermia to intensity-modulated radiotherapy (IMRT) plus neoadjuvant androgen deprivation therapy (ADT) for high-risk localized prostate carcinoma. Methods: Data from 121 consecutive patients with high-risk prostate carcinoma who were treated with IMRT were retrospectively analyzed. The total planned dose of IMRT was 76 Gy in 38 fractions for all patients; hyperthermia was used in 70 of 121 patients. Intra-rectal temperatures at the prostate level were measured to evaluate thermal dose. Results: Median number of heating sessions was five and the median total thermal dose of CEM43T90 was 7.5 min. Median follow-up duration was 64 months. Addition of hyperthermia to IMRT predicted better clinical relapse-free survival. Higher thermal dose with CEM43T90 (>7 min) predicted improved biochemical disease-free survival. The occurrence of acute and delayed toxicity ≥Grade 2 was not significantly different between patients with or without hyperthermia. Conclusions: IMRT plus regional hyperthermia represents a promising approach with acceptable toxicity for high-risk localized prostate carcinoma. Further studies are needed to verify the efficacy of this combined treatment.

The Antitumor Effect of Caffeic Acid Phenethyl Ester by Downregulating Mucosa-Associated Lymphoid Tissue 1 via AR/p53/NF-κB Signaling in Prostate Carcinoma Cells

Caffeic acid phenethyl ester (CAPE), a honeybee propolis-derived bioactive ingredient, has not been extensively elucidated regarding its effect on prostate cancer and associated mechanisms. The mucosa-associated lymphoid tissue 1 gene (MALT1) modulates NF-κB signal transduction in lymphoma and non-lymphoma cells. We investigated the functions and regulatory mechanisms of CAPE in relation to MALT1 in prostate carcinoma cells. In p53- and androgen receptor (AR)-positive prostate carcinoma cells, CAPE downregulated AR and MALT1 expression but enhanced that of p53, thus decreasing androgen-induced activation of MALT1 and prostate-specific antigen expressions. p53 downregulated the expression of MALT in prostate carcinoma cells through the putative consensus and nonconsensus p53 response elements. CAPE downregulated MALT1 expression and thus inhibited NF-κB activity in p53- and AR-negative prostate carcinoma PC-3 cells, eventually reducing cell proliferation, invasion, and tumor growth in vitro and in vivo. CAPE induced the ERK/JNK/p38/AMPKα1/2 signaling pathways; however, pretreatment with the corresponding inhibitors of MAPK or AMPK1/2 did not inhibit the CAPE effect on MALT1 blocking in PC-3 cells. Our findings verify that CAPE is an effective antitumor agent for human androgen-dependent and -independent prostate carcinoma cells in vitro and in vivo through the inhibition of MALT1 expression via the AR/p53/NF-κB signaling pathways.

418 Phase 1b/2 KEYNOTE-365 cohort I: platinum-containing chemotherapy alone or in combination with pembrolizumab for treatment-emergent neuroendocrine prostate carcinoma

BackgroundTreatment-emergent neuroendocrine prostate carcinoma (t-NE) can occur de novo or after diagnosis of prostate adenocarcinoma. Treatment often includes platinum-containing chemotherapy because of t-NE’s histologic similarity to small cell lung cancer. The PD-1 inhibitor pembrolizumab has shown promising efficacy and acceptable safety when combined with olaparib, docetaxel, or enzalutamide for treatment of metastatic castration-resistant prostate cancer (mCRPC) in the multicohort phase 1b/2 KEYNOTE-365 study (NCT02861573). Cohort I will be used to compare platinum-containing chemotherapy alone with chemotherapy + pembrolizumab as treatment for t-NE.MethodsPatients who have t-NE (≥1% neuroendocrine cells in a recent biopsy specimen confirmed by central histology review); experienced progression within 6 months of starting a next-generation hormonal agent (NHA) for mCRPC or hormone-sensitive prostate cancer and experienced progression within 6 cycles of docetaxel treatment for mCRPC; and have an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 are eligible. Prior therapy with ≤2 NHAs and 1 other chemotherapy for mCRPC is permitted. Patients will be randomly assigned 1:1 to receive pembrolizumab 200 mg IV on day 1 of each cycle every 3 weeks + carboplatin AUC of 5 IV on day 1 + etoposide 100 mg/m2 IV on days 1, 2, and 3 of each 21-day cycle for 4 cycles (arm 1) or the same chemotherapy regimen without pembrolizumab (arm 2); in each arm 40–100 patients will be enrolled. Pembrolizumab treatment will continue up to 2 years until disease progression, unacceptable toxicity, or withdrawal of consent. Patients will be stratified by ECOG performance status score (0 or 1). Computed tomography or magnetic resonance imaging will be performed every 9 weeks through week 54 and every 12 weeks thereafter. Primary end points are safety and tolerability, prostate-specific antigen (PSA) response rate, and objective response rate (ORR) per RECIST v1.1 by blinded independent central review (BICR). Secondary end points are time to PSA progression; ORR and radiographic progression-free survival (PFS) per PCWG3-modified RECIST v1.1 by BICR; duration of response and disease control rate per RECIST v1.1 by BICR and PCWG3-modified RECIST v1.1 by BICR; and overall survival. End points will be summarized for each arm without formal hypothesis testing.AcknowledgementsMedical writing and/or editorial assistance was provided by Matthew Grzywacz, PhD, of ApotheCom (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Funding for this research was provided by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.Trial RegistrationClinicaltrials.gov, NCT02861573Ethics ApprovalThe study and the protocol were approved by the Institutional Review Board or ethics committee at each site.