Ashley Jacobs

Abstract H3K27M-mutant diffuse midline gliomas (DMGs) express high levels of the disialoganglioside GD2 (ref. 1 ). Chimeric antigen receptor-modified T cells targeting GD2 (GD2-CART) eradicated DMGs in preclinical models 1 . Arm A of Phase I trial no. NCT04196413 (ref. 2 ) administered one intravenous (IV) dose of autologous GD2-CART to patients with H3K27M-mutant pontine (DIPG) or spinal DMG (sDMG) at two dose levels (DL1, 1 × 10 6 kg − 1 ; DL2, 3 × 10 6 kg −1 ) following lymphodepleting chemotherapy. Patients with clinical or imaging benefit were eligible for subsequent intracerebroventricular (ICV) intracranial infusions (10–30 × 10 6 GD2-CART). Primary objectives were manufacturing feasibility, tolerability and the identification of maximally tolerated IV dose. Secondary objectives included preliminary assessments of benefit. Thirteen patients enroled, with 11 receiving IV GD2-CART on study ( n = 3 DL1 (3 DIPG); n = 8 DL2 (6 DIPG, 2 sDMG)). GD2-CART manufacture was successful for all patients. No dose-limiting toxicities occurred on DL1, but three patients experienced dose-limiting cytokine release syndrome on DL2, establishing DL1 as the maximally tolerated IV dose. Nine patients received ICV infusions, with no dose-limiting toxicities. All patients exhibited tumour inflammation-associated neurotoxicity, safely managed with intensive monitoring and care. Four patients demonstrated major volumetric tumour reductions (52, 54, 91 and 100%), with a further three patients exhibiting smaller reductions. One patient exhibited a complete response ongoing for over 30 months since enrolment. Nine patients demonstrated neurological benefit, as measured by a protocol-directed clinical improvement score. Sequential IV, followed by ICV GD2-CART, induced tumour regressions and neurological improvements in patients with DIPG and those with sDMG.

H3K27M-mutant diffuse midline gliomas (DMGs) express high levels of the GD2 disialoganglioside and chimeric antigen receptor modified T-cells targeting GD2 (GD2-CART) eradicate DMGs in preclinical models. Arm A of the Phase I trial NCT04196413 administered one IV dose of autologous GD2-CART to patients with H3K27M-mutant pontine (DIPG) or spinal (sDMG) diffuse midline glioma at two dose levels (DL1=1e6/kg; DL2=3e6/kg) following lymphodepleting (LD) chemotherapy. Patients with clinical or imaging benefit were eligible for subsequent intracerebroventricular (ICV) GD2-CART infusions (10-30e6 GD2-CART). Primary objectives were manufacturing feasibility, tolerability, and identification of a maximally tolerated dose of IV GD2-CART. Secondary objectives included preliminary assessments of benefit. Thirteen patients enrolled and 11 received IV GD2-CART on study [n=3 DL1(3 DIPG); n=8 DL2(6 DIPG/2 sDMG). GD2-CART manufacturing was successful for all patients. No dose-limiting toxicities (DLTs) occurred on DL1, but three patients experienced DLT on DL2 due to grade 4 cytokine release syndrome (CRS). Nine patients received ICV infusions, which were not associated with DLTs. All patients exhibited tumor inflammation-associated neurotoxicity (TIAN). Four patients demonstrated major volumetric tumor reductions (52%, 54%, 91% and 100%). One patient exhibited a complete response ongoing for >30 months since enrollment. Eight patients demonstrated neurological benefit based upon a protocol-directed Clinical Improvement Score. Sequential IV followed by ICV GD2-CART induced tumor regressions and neurological improvements in patients with DIPG and sDMG. DL1 was established as the maximally tolerated IV GD2-CART dose. Neurotoxicity was safely managed with intensive monitoring and close adherence to a management algorithm.

Abstract Background: H3K27M-mutated DMGs are universally lethal central nervous system tumors that express high levels of the disialoganglioside GD2. IV administered GD2-CAR T cells (GD2-CART) regress DMG in preclinical models, and locoregionally delivered CARs demonstrate enhanced activity in xenograft models of brain tumors. Methods: NCT04196413 is a 3+3 Phase I dose escalation trial testing GD2-CART in patients with H3K27M DMG, with dose-limiting toxicities (DLT) considered independently for DIPG and spinal DMG (sDMG). Arm A tested escalating doses of IV GD2-CART (DL1: 1e6 GD2-CART/kg; DL2=3e6 GD2-CART/kg) following lymphodepletion (LD). After the DLT period, patients with clinical and/or radiographic benefit were eligible for subsequent ICV GD2-CART (10-30e6 GD2-CART) administered via Ommaya catheter without LD every 4-8 weeks for a maximum of 12 doses. We previously reported early results from 4 patients treated on DL1, which demonstrated clinical activity and manageable toxicity. Here we provide updated results for DL1 and DL2. Results: Thirteen subjects were enrolled and 11 treated [n=4 DL1 (3 DIPG/1 sDMG); n=9 DL2 (7 DIPG/2 sDMG)]. Two subjects were removed prior to treatment due to rapid progression. No DLTs were observed on DL1. Three subjects experienced DLT on DL2 (2 DIPG/1 sDMG) due to grade 4 cytokine release syndrome (CRS), successfully managed with tocilizumab, anakinra, and corticosteroids. CRS occurred earlier on DL2 vs. DL1 (Day 3 vs 7). On both dose levels, all subjects exhibited transient symptoms related to on-tumor inflammation, termed Tumor Inflammation-Associated Neurotoxicity (TIAN), which was successfully managed with anakinra and, in some cases, CSF drainage and dexamethasone. No DLT due to TIAN has occurred. Ten patients have had adequate follow-up to assess benefit. Nine experienced radiographic and/or clinical benefit after IV infusion, and they received subsequent ICV GD2-CART infusions (median= 4 ICV infusions/pt, range 1-6). ICV infusions were not associated with high-grade CRS, although some subjects developed transient fever, headache, meningismus, nausea, and/or vomiting, and several subjects developed TIAN. Four patients continue to receive ICV infusions on study and have experienced continued clinical and radiographic benefit at 11+, 9.5+, 8+ and 7+ months following enrollment. A 31-year-old with sDMG has experienced a near-complete (>95%) reduction in tumor volume and a 17-year-old with DIPG experienced a near-complete (>98%) reduction in volume of a pontine tumor. Conclusions: IV treatment of DIPG and sDMG with GD2-CART is safe at a dose of 1e6/kg, but associated with unacceptable rates of high-grade CRS at 3e6/kg. ICV GD2-CART without LD, administered following a previous course of IV GD2-CART with LD, has been well tolerated and has mediated impressive sustained clinical benefit in some patients with DIPG/sDMG. Given these findings, we are launching a new arm to assess safety and activity and to define the recommended phase 2 dose for ICV delivery of GD2-CART without LD. Patients are eligible for up to 12 ICV infusions of GD2-CART administered every 4-6 weeks. Clinical benefit will be formally assessed using patient-reported outcomes. GD2-CART has the potential to transform therapy for patients with H3K27M+ DIPG/sDMG. Citation Format: Robbie G. Majzner, Jasia Mahdi, Sneha Ramakrishna, Shabnum Patel, Harshini Chinnasamy, Kristen Yeom, Liora Schultz, Valentin Barsan, Rebecca Richards, Cynthia Campen, Agnes Reschke, Angus Martin Shaw Toland, Christina Baggott, Sharon Mavroukakis, Emily Egeler, Jennifer Moon, Ashley Jacobs, Karen Yamabe-Kwong, Lindsey Rasmussen, Esther Nie, Sean Green, Michael Kunicki, Michelle Fujimoto, Zach Ehlinger, Warren Reynolds, Snehit Prabhu, Katherine E. Warren, Tim Cornell, Sonia Partap, Paul Fisher, Gerald Grant, Hannes Vogel, Bita Sahaf, Kara Davis, Steven Feldman, Michelle Monje, Crystal L. Mackall. Major tumor regressions in H3K27M-mutated diffuse midline glioma (DMG) following sequential intravenous (IV) and intracerebroventricular (ICV) delivery of GD2-CAR T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT001.