Phase 1 / 2 Study of SAR439859 Single Agent and in Combination With Palbociclib in Postmenopausal Women With Estrogen Receptor Positive Advanced Breast Cancer

Study Overview

Primary Objectives:

Dose Escalation: Part A (SAR439859 monotherapy); Part C (combination of SAR439859 with palbociclib)

• To determine the maximum tolerated dose (MTD) and recommended dose (RD) of SAR439859 based on the dose-limiting toxicity (DLT) observance in monotherapy (Part A), and in combination with palbociclib (Part C)

Dose Expansion: Part B (SAR439859 monotherapy); Part D (combination of SAR439859 with palbociclib)

• To assess antitumor activity by Objective Response Rate (ORR) at the SAR439859 recommended dose in monotherapy (Part B), and in combination with palbociclib (Part D)

Secondary Objectives:

• Overall safety profile of SAR439859 as monotherapy (Parts A, B), and in combination with palbociclib (Parts C, D)
• Pharmacokinetic (PK) profile of SAR439859 as monotherapy (Parts A, B), and of SAR439859 in combination with palbociclib (Parts C, D), and of palbociclib in combination with SAR439859 (Parts C, D)
• Antitumor activity of SAR439859 as monotherapy (Part A), and in combination with palbociclib (Part C) as well as the Clinical Benefit Rate (CBR: Complete Response [CR], Partial Response [PR] and Stable Disease [SD] =24 weeks) in Parts A, B, C, and D
• ORR and CBR (CR, PR and SD =24 weeks) according to the estrogen receptor 1 (ESR1) gene mutational status (mutant and wild type) at baseline and in treatment
• Time to first tumor response (CR or PR) in Parts B and D
• Residual estrogen receptor (ER) availability with [(18)F] Fluoroestradiol Positron Emission Tomography (FES PET) scan (Part A)
• To assess potential induction/inhibition effect of SAR439859 on CYP3A (Part B)

• ClinicalTrials.gov Identifier: NCT03284957
• Protocol Number: 17-371
• Principal Investigator: Jaymin Patel