P06.18.b overview of the glitipni trial - local administration of immune checkpoint inhibition and/or dendritic cells following resection of recurrent glioblastoma

Abstract BACKGROUND Intravenous (IV) administration of the Immune checkpoint inhibitor (ICI) nivolumab (NIVO) for recurrent glioblastoma (rGB) has proven mostly ineffective, and the combination of IV ipilimumab (IPI) plus nivolumab (NIVO) is associated with a high incidence of irAE. Combinatorial immunotherapy strategies are likely to be more effective, and direct Intracerebral (iCE) administration following the resection of rGB could be a more effective and safer alternative to iv-dosing METHODS We previously demonstrated that intra-operative intracerebral (iCE) administration of the Immune checkpoint inhibitors (ICI) ipilimumab (IPI) and nivolumab (NIVO) after resection of recurrent glioblastoma (rGB) is safe and resulted in encouraging survival. The adaptive phase I Glitipni trial was further expanded with more cohorts (C) exploring the implantation of an Ommaya reservoir for intracavitary (iCav) administration of escalating doses of ICI, complementary iCE injection of increasing numbers of myeloid dendritic cells (myDC). We provide an overarching overview of all patients included in the program. RESULTS 102 patients have been included in the Glitipni trial. In C1 and 2 (3 and 24 patients) iCE IPI and IPI+NIVO were followed by IV NIVO every two weeks. Next, we combined this peroperative backbone with postoperative iCav injection of NIVO 1-/5-/10 mg every two weeks through an Ommaya reservoir following stereotactic biopsy (C3, 16 patients) or resection (C4, 16 patients). No dose-related toxicity was seen for iCav NIVO. iCE injection of BDCA-1 and BDCA-3+ myDC (escalating from 1-/10- to 20.10E6) was added to the backbone of C3/4 with adjuvant 10mg iCav NIVO (resection in C5, 11 patients, biopsy in C6, 2 patients). In C7 (27+patients), patients had resection, iCE IPI+NIVO, and postoperative IV NIVO with iCav NIVO 10mg and IPI escalating 1/5/10mg. Dose limiting toxicity (aseptic neutrophilic pleocytosis) was encountered with iCav IPI (5-10mg Q2w). Median Overall Survival (mOS) was 38 weeks (C1/2), 23 weeks (C3), 42 weeks (C4), 44 weeks (C5/6) and 40 weeks (C7) CONCLUSION Peroperative iCer administration of IPI and NIVO is feasible and associated with an acceptable safety profile. A potential beneficial effect on overall survival was restricted to patients with resectable recurrences. Addition of myDC my improve PFS and OS. There is no indication for an additional benefit of adjuvant iCav IPI or NIVO. Further research will expand on iCer myDC administration and investigate complementary neo-adjuvant ICI administration.