Saeed Rafii

Phase I, dose-escalation, two-part trial of the PARP inhibitor talazoparib in patients with advanced germline BRCA1/2 mutations and selected sporadic cancers

Talazoparib inhibits PARP catalytic activity, trapping PARP1 on damaged DNA and causing cell death in BRCA1/2-mutated cells. We evaluated talazoparib therapy in this two-part, phase I, first-in-human trial. Antitumor activity, MTD, pharmacokinetics, and pharmacodynamics of once-daily talazoparib were determined in an open-label, multicenter, dose-escalation study (NCT01286987). The MTD was 1.0 mg/day, with an elimination half-life of 50 hours. Treatment-related adverse events included fatigue (26/71 patients; 37%) and anemia (25/71 patients; 35%). Grade 3 to 4 adverse events included anemia (17/71 patients; 24%) and thrombocytopenia (13/71 patients; 18%). Sustained PARP inhibition was observed at doses ≥0.60 mg/day. At 1.0 mg/day, confirmed responses were observed in 7 of 14 (50%) and 5 of 12 (42%) patients with BRCA mutation-associated breast and ovarian cancers, respectively, and in patients with pancreatic and small cell lung cancer. Talazoparib demonstrated single-agent antitumor activity and was well tolerated in patients at the recommended dose of 1.0 mg/day.Significance: In this clinical trial, we show that talazoparib has single-agent antitumor activity and a tolerable safety profile. At its recommended phase II dose of 1.0 mg/day, confirmed responses were observed in patients with BRCA mutation-associated breast and ovarian cancers and in patients with pancreatic and small cell lung cancer. Cancer Discov; 7(6); 620-9. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 539.

Higher Risk of Infections with PI3K–AKT–mTOR Pathway Inhibitors in Patients with Advanced Solid Tumors on Phase I Clinical Trials

Purpose: Novel antitumor therapies against the PI3K–AKT–mTOR pathway are increasingly used to treat cancer, either as single agents or in combination with chemotherapy or other targeted therapies. Although these agents are not known to be myelosuppressive, an increased risk of infection has been reported with rapamycin analogues. However, the risk of infection with new inhibitors of this pathway such as PI3K, AKT, mTORC 1/2, or multikinase inhibitors is unknown. Experimental Design: In this retrospective case–control study, we determined the incidence of infection in a group of 432 patients who were treated on 15 phase I clinical trials involving PI3K–AKT–mTOR pathway inhibitors (cases) versus a group of 100 patients on 10 phase I clinical trials of single agent non-PI3K–AKT–mTOR pathway inhibitors (controls) which did not involve conventional cytotoxic agents. We also collected data from 42 patients who were treated with phase I trials of combinations of PI3K–AKT–mTOR inhibitors and MEK inhibitors and 24 patients with combinations of PI3K–AKT–mTOR inhibitors and cytotoxic chemotherapies. Results: The incidence of all grade infection was significantly higher with all single-agent PI3K–AKT–mTOR inhibitors compared with the control group [27% vs. 8%, respectively, OR, 4.26; 95% confidence intervals (CI), 1.9–9.1, P = 0.0001]. The incidence of grade 3 and 4 infection was also significantly higher with PI3K–AKT–mTOR inhibitors compared with the control group (10.3% vs. 3%, OR, 3.74; 95% CI, 1.1–12.4; P = 0.02). Also, the combination of PI3K–AKT–mTOR inhibitors and chemotherapy was associated with a significantly higher incidence of all grade (OR, 4.79; 95% CI, 2.0–11.2; P = 0.0001) and high-grade (OR, 2.87; 95% CI, 1.0–7.6; P = 0.03) infection when compared with single-agent PI3K–AKT–mTOR inhibitors. Conclusions: Inhibitors of the PI3K–AKT–mTOR pathway can be associated with a higher risk of infection. Combinations of PI3K–AKT–mTOR inhibitors and cytotoxic chemotherapy significantly increase the risk of infection. This should be taken into consideration during the design and conduct of trials involving PI3K–AKT–mTOR pathway inhibitors, particularly when combined with chemotherapy or myelosuppressive agents. Clin Cancer Res; 21(8); 1869–76. ©2015 AACR.

Complications of hyperglycaemia with PI3K–AKT–mTOR inhibitors in patients with advanced solid tumours on Phase I clinical trials

Background:PI3K–AKT–mTOR inhibitors (PAMi) are promising anticancer treatments. Hyperglycaemia is a mechanism-based toxicity of these agents and is becoming increasingly important with their use in larger numbers of patients.Methods:Retrospective case-control study comparing incidence and severity of hyperglycaemia (all grades) between a case group of 387 patients treated on 18 phase I clinical trials with PAMi (78 patients with PI3Ki, 138 with mTORi, 144 with AKTi and 27 with PI3K/mTORi) and a control group of 109 patients treated on 10 phase I clinical trials with agents not directly targeting the PAM pathway. Diabetic patients were excluded in both groups.Results:The incidence of hyperglycaemia was not significantly different between cases and controls (86.6% vs 80.7%, respectively, P=0.129). However, high grade (grade 3–4) hyperglycaemia was more frequent in the PAMi group than in controls (6.7% vs 0%, respectively, P=0.005). The incidence of grade 3–4 hyperglycaemia was greater with AKT and multikinase inhibitors compared with other PAMi (P<0.001). All patients with high-grade hyperglycaemia received antihyperglycemic treatment and none developed severe metabolic complications (diabetic ketoacidosis or hyperosmolar hyperglycemic nonketotic state). High-grade hyperglycaemia was the cause of permanent PAMi discontinuation in nine patients.Conclusions:PI3K–AKT–mTOR inhibitors are associated with small (6.7%) but statistically significant increased risk of high-grade hyperglycaemia compared with non-PAM targeting agents. However, PAMi-induced hyperglycaemia was not found to be associated with severe metabolic complications in this non-diabetic population of patients with advanced cancers.

Baseline clinical predictors of antitumor response to the PARP inhibitor olaparib in germline BRCA1/2 mutated patients with advanced ovarian cancer

Background The PARP inhibitor olaparib was recently granted Food and Drug Administration (FDA) accelerated approval in patients with advanced BRCA1/2 mutation ovarian cancer. However, antitumor responses are observed in only approximately 40% of patients and the impact of baseline clinical factors on response to treatment remains unclear. Although platinum sensitivity has been suggested as a marker of response to PARP inhibitors, patients with platinum-resistant disease still respond to olaparib. Results 108 patients with advanced BRCA1/2 mutation ovarian cancers were included. The interval between the end of the most recent platinum chemotherapy and PARPi (PTPI) was used to predict response to olaparib independent of conventional definition of platinum sensitivity. RECIST complete response (CR) and partial response (PR) rates were 35% in patients with platinum-sensitive versus 13% in platinum-resistant (p<0.005). Independent of platinum sensitivity status, the RECIST CR/PR rates were 42% in patients with PTPI greater than 52 weeks and 18% in patients with PTPI less than 52 weeks (p=0.016). No association was found between baseline clinical factors such as FIGO staging, debulking surgery, BRCA1 versus BRCA2 mutations, prior history of breast cancer and prior chemotherapy for breast cancer, and the response to olaparib. Methods We conducted an international multicenter retrospective study to investigate the association between baseline clinical characteristics of patients with advanced BRCA1/2 mutation ovarian cancers from eight different cancer centers and their antitumor response to olaparib. Conclusion PTPI may be used to refine the prediction of response to PARP inhibition based on the conventional categorization of platinum sensitivity.

863PPREDICTIVE FACTORS OF SURVIVAL FOR PATIENTS WITH BLADDER CANCER (BC) IN PHASE I CLINICAL TRIALS

ABSTRACT Background: There are limited anticancer therapies available for BC. Novel targeted therapies (TT) may offer more treatment options. Methods: Retrospective data was collected on clinical treatment and tumour characteristics on patients (pts) with BC treated in the Drug Development Unit, at the Royal Marsden Hospital (RMH) between August 1996 and January 2014.Survival analyses were performed using the Kaplan-Meier method and Cox proportional hazards model, and associations were tested with Fischers Exact test. Results: 125 pts with BC were referred and 36 (29%) were treated. Median age was 58 yrs (range: 30-68). 7 female, 38% ECOG 0 and 62% ECOG 1-2. Histological types included: transitional cell (n = 24), squamous cell (n = 2), urachal (n = 2), papillary cell (n = 2) and adenocarcinoma (n = 2). 51% pts had 1 line of prior treatment, 33% 2 lines and 16% ≥3 lines.Pts were treated on 20 phase 1 trials; 6 trials were combination chemotherapy and TT, and 14 trials were single agents, targeting: PI3K (n = 3), HDAC (n = 3), EGFR/VEGFR (n = 3), oncolytic viruses (n = 2), mTOR (n = 1), AKT (n = 1), PARP (n = 1), TS (n = 1), c-MET (n = 1), nucleoside (n = 1), microtubule (n = 1), Rho (n = 1) and Bcl2 (n = 1). Median time on trial was 1.8 months (m; range: 0.1 -15.6).Objective response rate was 14%, and the clinical benefit rate (CBR: CR + PR + SD) was 47%, as defined by RECIST 1.0. Median overall survival (OS) for pts with a CB was 9.2 m versus 3.3 m for pts with progressive disease (HR0.29, CI 0.07-0.037,P Conclusions: Predictors of OS for BC patients on phase I clinical trials include CB and WCC. The number of BC pts treated is low, although outcomes are comparable to the general phase I patient population. With the limited treatment options available for this group, phase 1 trial participation should be considered at an earlier stage for these patients. Disclosure: All authors have declared no conflicts of interest.