Abstract
e13075 Background: Metastatic triple negative breast cancer (TNBC) is a disease subtype with a poor prognosis, though advancements have been made in the use of targeted therapies, such as poly (ADP-ribose) polymerase inhibitors (PARPi) for those with germline BRCA 1/2 mutations. Up to 2/3 of TNBC tumors have acquired defects in homologous recombination (HR) DNA repair, yet PARPi monotherapy has been ineffective in extending survival in these patients. Phosphoinositide-3-kinase (PI3K)/mTOR pathway alterations are also common, and preclinical data supports that PI3K/mTOR inhibition may disrupt normal function of the HR complex and increase dependency on PARP enzymes for HR DNA repair. Thus, combining a PI3K/mTORi with a PARPi may result in a synergistic anti-neoplastic effect. Methods: The safety run-in portion of this study evaluated the safety and preliminary efficacy of the combination of weekly IV gedatolisib (PI3K/mTORi) and continuous daily talazoparib. Germline BRCA mutations were not required. The safety run-in was designed to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). A 3+3 design was utilized for dose escalation, with starting dose at level 1. Dose levels are as shown in the Table. Eligibility criteria included patients ≥ age 18 who had received 1-3 prior lines of therapy for advanced TNBC or advanced HER2-negative BC with a germline BRCA 1/2 mutation. Those with untreated CNS metastasis were excluded as were those type I diabetes or uncontrolled type II diabetes, due to the risk of hyperglycemia with gedatolisib. Results: A total of 14 female patients were enrolled on to the safety run-in phase of the trial. Median age was 53 (range 30-67). Most patients (79%) were Caucasian, 14% were African American, and 7% unknown. The most common adverse events (AEs) of any grade were fatigue, anemia, nausea, and oral mucositis. Grade 1 hyperglycemia was noted in about 1/3 of the cohort, with 1 grade 3 event. There were 3 patients who experienced grade 4 AEs, thrombocytopenia (2) and lymphopenia (1). There was 1 DLT of grade 3 neutropenia which occurred at dose level 1. The MTD of gedatolisib was 180 mg and MTD of talazoparib was 1 mg. In this preliminary cohort, 3 patients achieved PR and 5 patients achieved SD. Median duration of PR was 13.34 months and median duration of SD was 4.11 months. Of the 3 patients with a BRCA 1 or 2 mutation, 2 had a best response of PR and the other SD. Conclusions: The safety run-in indicated that this combination is safe and well tolerated with mostly grade 1-2 AEs. This combination therapy has moved into the phase II trial, with 2 cohorts. Cohort A includes BRCA-wildtype patients with TNBC and cohort 2 includes those with a BRCA mutation and HER2-negative disease. Clinical trial information: NCT03911973. [Table: see text]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.