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Results from a phase 2b, randomized, multicenter study of GVAX pancreas and CRS-207 compared to chemotherapy in adults with previously-treated metastatic pancreatic adenocarcinoma (ECLIPSE Study).
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2017
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Clinical ImmunologyImmunologyImmune RegulationPathologyImmunoeditingImmunotherapeuticsImmune SystemImmunotherapyCrs-207 TreatmentOncologyPancreatic CancerGastrointestinal OncologyTumor ImmunityRadiation OncologyCancer ResearchMolecular OncologyHigh Dropout RatesPhase 2BImmune SurveillanceHumoral ImmunityT Cell ImmunityHigh Dropout RateCancer ImmunosurveillanceGvax PancreasMedicineEclipse Study
345 Background: GVAX is composed of irradiated, allogeneic pancreatic cancer cells modified to express GM-CSF and induce broad tumor antigen responses. Low-dose cyclophosphamide (CY) is administered with GVAX to inhibit regulatory T cells. CRS-207 is live, attenuated, double-deleted Listeria monocytogenes(LADD) engineered to express mesothelin. CRS-207 boosts T cell responses against mesothelin and stimulates innate and adaptive immunity. In an earlier Phase 2 study in patients with mPDA, CY/GVAX + CRS-207 resulted in a significant improvement in overall survival (OS) compared to CY/GVAX alone. Methods: Patients with previously-treated mPDA were randomized 1:1:1 to receive 2 doses of CY/GVAX + 4 doses of CRS-207 (Arm A), 6 doses of CRS-207 alone (Arm B), or physician’s choice of single-agent chemotherapy (Arm C). Two cohorts were included based on number of prior lines of therapy; the primary cohort (PC) represented those with ≥ 2 prior lines. The primary objective was to compare OS between Arms A and C in the PC. Additional objectives include OS analyses between all treatment arms, safety, tumor responses and immune analyses. Results: 303 patients were enrolled: 213 in the PC and 90 in an exploratory 2 nd -line cohort (SC). Common AEs associated with CRS-207 treatment included transient fevers, chills, and nausea. High dropout rates were observed in Arm C prior to treatment (40% in PC, 63% in SC). Clinical trial information: NCT02004262 . Subset and immune analyses, as well as OS data from SC, will be presented at the meeting. Conclusions: The combination of CY/GVAX + CRS-207 did not show a survival benefit over chemotherapy in patients with previously-treated mPDA, although survival of patients receiving CRS-207 alone appeared similar to chemotherapy. The regimens were well tolerated with no new significant safety findings. The high dropout rate in the chemotherapy arm demonstrates a potential challenge for conventional controls in immunotherapy trials. [Table: see text]