Abstract OT1-01-05: AIPAC (Active Immunotherapy PAClitaxel): A randomized, double blind, placebo controlled, multinational phase IIb trial evaluating the efficacy of eftilagimod alpha (a soluble LAG-3 fusion protein) in combination with paclitaxel in hormone receptor positive metastatic breast cancer

Abstract

Abstract Background: Eftilagimod alpha (efti, previously IMP321) is a recombinant LAG-3Ig fusion protein that binds to MHC class II and mediates antigen-presenting cell (APC) activation followed by CD8 T-cell activation. Efti may lead to the activation of the dendritic cell network and to a strong anti-tumor CD8 T cell response when injected s.c. after chemotherapy at a time when these APC are loaded with tumor antigens. AIPAC (Active Immunotherapy PAClitaxel; NCT02614833) is a Phase IIb trial in hormone receptor (HR)-positive metastatic breast carcinoma patients receiving efti or placebo as adjunctive to weekly paclitaxel as a first-line chemotherapy. The randomized double blinded part (stage 2) has finished recruitment in June 2019. Primary analysis is expected Q1 2020. Methods: This clinical trial is a placebo-controlled, double-blind, 1:1 randomized Phase IIb study aimed to enrol 226 patients at multiple centres across 7 different European countries. Patients with metastatic, HR-positive breast adenocarcinoma receiving first line chemotherapy with weekly paclitaxel and with measurable disease according to RECIST 1.1 are eligible. Patients suitable for Her2/neu targeted therapy are excluded from the trial. In the first treatment phase, paclitaxel (80 mg/m² IV at D1, D8, D15 plus efti (30 mg s.c.) or placebo at D2, D16 will be administered for 6 cycles (1 cycle = 4 weeks). This is followed by a maintenance phase in which stable or responding patients will receive efti or placebo for up to additional 52 weeks (12 injections). The primary endpoint is progression-free survival (PFS) by blinded independent central imaging review. Secondary endpoints include PFS by local assessment, overall survival, tumor response according to RECIST 1.1., time to and duration of response, duration of stable disease and quality of life. Citation Format: Luc Dirix, Hans Wildiers, Manon T Huizing, Eveline De Cuypere, Carolina P Schröder, Anne C Armstrong, Jans Huober, Frederik Marmé, Andreas Schneeweiss, Sarah Khan, Fréderic Triebel. AIPAC (Active Immunotherapy PAClitaxel): A randomized, double blind, placebo controlled, multinational phase IIb trial evaluating the efficacy of eftilagimod alpha (a soluble LAG-3 fusion protein) in combination with paclitaxel in hormone receptor positive metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-01-05.