CTIM-05. COMBINATION OF CONTROLLED INTERLEUKIN-12 GENE THERAPY WITH IMMUNE CHECKPOINT BLOCKADE IN RECURRENT GLIOBLASTOMA: UPDATED RESULTS OF A MULTI-INSTITUTIONAL, OPEN LABEL PHASE 1 TRIAL

Abstract

A published clinical trial of veledimex (V)-regulatable interleukin-12 (IL-12) gene therapy (“Controlled IL-12”) under the control of a transcriptional switch (RheoSwitch Therapeutic Systemâ, RTSâ) as monotherapy in recurrent glioblastoma (rGBM) showed sustained infiltration of activated T cells within the tumor months after treatment (Sci Transl Med. 2019;11(505)). These T cells demonstrated up-regulation of immune checkpoint signaling, providing a rationale for combination therapy with the PD-1 inhibitor, nivolumab (nivo). We report interim findings following completion of enrollment (with follow-up ongoing) for a multi-institutional, open label, dose-escalation phase 1 trial (NCT03636477) evaluating safety and tolerability of loco-regional Controlled IL-12 in combination with nivo in adults with rGBM. Replication-incompetent adenovirus coding for RTS-IL-12 (Ad) was administered during surgery by free-hand injection into the tumor and periphery (2 x 1011 viral particles, Day 0) accompanied by V (10 or 20 mg) PO QD x 15 (Days 0 to 14) in combination with nivo (1 or 3 mg/kg) IV on Days -7, 15, then Q2W. Twenty-one subjects were treated (Cohort 1: V 10 mg, nivo 1 mg/kg, n=3; Cohort 2: V 10 mg, nivo 3 mg/kg, n=3; and Cohort 3: V 20 mg, nivo 3 mg/kg, n=3 & 12 in expansion). Safety data were comparable to Ad+V monotherapy. Adverse reactions (ARs) during follow-on nivo dosing were consistent with nivo labeling. ARs were manageable and generally reversible with no synergistic toxicities. Updated overall survival findings will be presented. Baseline and post-treatment histochemical staining and multiplex immunofluorescence analyses for a subgroup of subjects will be discussed. The safety of this combination immunotherapy has been established, leading to a currently accruing phase 2 clinical trial of loco-regional Controlled IL-12 gene therapy in combination with the PD-1 inhibitor cemiplimab-rwlc (NCT 04006119).