Harshini Chinnasamy

Abstract Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal paediatric tumours of the central nervous system 1 . We have previously shown that the disialoganglioside GD2 is highly expressed on H3K27M-mutated glioma cells and have demonstrated promising preclinical efficacy of GD2-directed chimeric antigen receptor (CAR) T cells 2 , providing the rationale for a first-in-human phase I clinical trial (NCT04196413). Because CAR T cell-induced brainstem inflammation can result in obstructive hydrocephalus, increased intracranial pressure and dangerous tissue shifts, neurocritical care precautions were incorporated. Here we present the clinical experience from the first four patients with H3K27M-mutated DIPG or spinal cord DMG treated with GD2-CAR T cells at dose level 1 (1 × 10 6 GD2-CAR T cells per kg administered intravenously). Patients who exhibited clinical benefit were eligible for subsequent GD2-CAR T cell infusions administered intracerebroventricularly 3 . Toxicity was largely related to the location of the tumour and was reversible with intensive supportive care. On-target, off-tumour toxicity was not observed. Three of four patients exhibited clinical and radiographic improvement. Pro-inflammatory cytokine levels were increased in the plasma and cerebrospinal fluid. Transcriptomic analyses of 65,598 single cells from CAR T cell products and cerebrospinal fluid elucidate heterogeneity in response between participants and administration routes. These early results underscore the promise of this therapeutic approach for patients with H3K27M-mutated DIPG or spinal cord DMG.

Abstract Despite impressive progress, more than 50% of patients treated with CD19-targeting chimeric antigen receptor T cells (CAR19) experience progressive disease. Ten of 16 patients with large B cell lymphoma (LBCL) with progressive disease after CAR19 treatment had absent or low CD19. Lower surface CD19 density pretreatment was associated with progressive disease. To prevent relapse with CD19 − or CD19 lo disease, we tested a bispecific CAR targeting CD19 and/or CD22 (CD19-22.BB.z-CAR) in a phase I clinical trial ( NCT03233854 ) of adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) and LBCL. The primary end points were manufacturing feasibility and safety with a secondary efficacy end point. Primary end points were met; 97% of products met protocol-specified dose and no dose-limiting toxicities occurred during dose escalation. In B-ALL ( n = 17), 100% of patients responded with 88% minimal residual disease-negative complete remission (CR); in LBCL ( n = 21), 62% of patients responded with 29% CR. Relapses were CD19 −/lo in 50% (5 out of 10) of patients with B-ALL and 29% (4 out of 14) of patients with LBCL but were not associated with CD22 −/lo disease. CD19/22-CAR products demonstrated reduced cytokine production when stimulated with CD22 versus CD19. Our results further implicate antigen loss as a major cause of CAR T cell resistance, highlight the challenge of engineering multi-specific CAR T cells with equivalent potency across targets and identify cytokine production as an important quality indicator for CAR T cell potency.

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.

BACKGROUND: Outcomes are poor for patients with large B-cell lymphoma who relapse after CD19-directed chimeric antigen receptor (CAR) T-cell therapy (CAR19). CD22 is a nearly universally expressed B-cell surface antigen and the efficacy of a CD22-directed CAR T-cell therapy (CAR22) in large B-cell lymphoma is unknown, which was what we aimed to examine in this study. METHODS: In this single centre, open-label, dose-escalation phase 1 trial, we intravenously administered CAR22 at two dose levels (1 million and 3 million CAR22-positive T cells per kg of bodyweight) to adult patients (aged ≥18 years) who relapsed after CAR19 or had CD19-negative large B-cell lymphoma. The primary endpoints were manufacturing feasibility, safety measured by the incidence and severity of adverse events and dose-limiting toxicities, and identification of the maximum tolerated dose (ie, the recommended phase 2 dose). This study is registered with ClinicalTrials.gov (NCT04088890) and is active, but closed for enrolment. FINDINGS: From Oct 17, 2019, to Oct 19, 2022, a total of 41 patients were assessed for eligibility; however, one patient withdrew. 40 patients underwent leukapheresis and 38 (95%) had CAR T-cell products manufactured successfully. The median age was 65 years (range 25-84), 17 (45%) were women, 32 (84%) had elevated pretreatment lactate dehydrogenase, 11 (29%) had refractory disease to all previous therapies, and patients had received a median of four lines of previous therapy (range 3-8). Of the 38 patients treated, 37 (97%) had relapsed after previous CAR19. The identified maximum tolerated dose was 1 million CAR T cells per kg. Of 29 patients who received the maximum tolerated dose, no patients developed a dose-limiting toxicity or grade 3 or higher cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, or immune effector cell-associated haemophagocytic lymphohistiocytosis-like syndrome. INTERPRETATION: This trial identifies CD22 as an immunotherapeutic target in large B-cell lymphoma and demonstrates the durable clinical activity of CAR22 in patients with disease progression after CAR19 therapy. Although these findings are promising, it is essential to recognise that this is a phase 1 dose-finding study. Further investigations are warranted to establish the long-term efficacy and to delineate the patient subgroups that will derive the most benefit from this therapeutic approach. FUNDING: National Cancer Institute, National Institutes of Health, Stanford Cancer Institute, Leukemia & Lymphoma Society, Parker Institute for Cancer Immunotherapy, Lymph & Co, and the European Hematology Association.