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Case Reports
PD-1 blockade after bispecific LV20.19 CAR T modulates CAR T-cell immunophenotype without meaningful clinical response
Progression after anti-CD19 chimeric antigen receptor T (CAR T) cells is a major limitation of this novel form of immunotherapy. Proposed mechanisms of resistance include downregulation of target antigen and loss of CAR T-cell persistence.1 As part of a phase I, single-center clini- cal trial, patients with relapsed, refractory (R/R) B-cell non-Hodgkin lymphoma were given bispecific lentiviral anti-CD20, anti-CD19 (LV20.19) CAR T cells to mitigate resistance due to CD19 antigen loss.2,3 Among treatment failures, loss of CD19 was not identified and several patients who experienced treatment failures main- tained high levels of CAR T cells at relapse.2 We hypothe- sized that T-cell exhaustion or tumor checkpoint upregula- tion could be contributing to treatment failures. One pro- posed approach to mitigate these effects in CAR T cells has been through PD-1 inhibitors. For patients who progress after anti-CD19 CAR T, there are reports suggesting that PD-1 inhibitors at time of relapse could lead to response in some.4-6 However, currently published data is limited to anti-CD19 CAR T cells with no data on the use of PD-1 inhibitors after bispecific CAR T cells. We describe two cases, detailing the clinical and immunophenotypic impacts of giving pembrolizumab, a PD-1 inhibitor, after failure of LV20.19 CAR T therapy.
In order to evaluate the impact of pembrolizumab on CAR T cells, cryopreserved peripheral blood mononuclear cell (PBMC) samples from two patients treated on a phase I clinical trial with LV20.19 CAR T cells (clinicaltrials gov. Identifier: NCT03019055) were thawed and analyzed by
flow cytometry to determine immunophenotypic profile and persistence. Markers of T-cell exhaustion (PD1 [CD279], LAG3 [CD223] and TIM-3 [CD366]) and T-cell activation (CD154 [CD40L], CD25 [IL2RA], and CD137 [4-1BB]) were assessed before and after administration of PD-1 inhibitor. Institutional Review Board submission was deferred per institutional policy for case series including less than three patients.
Patient 1 is a 56-year-old man diagnosed with stage IV c-MYC+ diffuse large B-cell lymphoma (DLBCL) who achieved a complete remission (CR) with R-CHOP. He progressed within 6 weeks and achieved a CR with R-ICE (rituximab, ifosfamide, carboplatin and etoposide). Autologous hematopoietic cell transplant (HCT) was planned but relapse occurred within 4 weeks. The patient’s disease was then refractory to R-GDP (rituximab, gemcitabine, cisplatin, and dexamethasone). LV20.19 CAR T cells were given at a dose of 2.5x105 cells/kg. His course was complicated by grade 1 cytokine release syndrome (CRS) and neurotoxicity which did not require treatment. Flow cytometry studies demonstrated exponential expan- sion of circulating CAR T cells (Figure 1A); however, day 28 positron emission tomography–computed tomography (PET/CT) demonstrated progressive disease (PD). Day 34 biopsy revealed no meaningful change in CD19 or CD20 expression (93% and 97% at relapse; 73% and 97% pre- CAR T) (Figure 2A and B). Infiltrating T cells in relapse biopsy were seen (Figure 2C). Flow cytometry revealed 21% of infiltrating T cells were CAR+ whereas 54% of cir- culating T cells were CAR+ at relapse. PD-L1 expression in the relapse specimen was 5-10% (Figure 2D). The patient’s pre-CAR T biopsy had absent PD-L1 expression. Pembrolizumab 200 mg was given intravenously (IV) on day 36. Day 51 CT revealed a decrease in the dominant
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Figure 1. Chimeric antigen receptor (CAR) T-cell product composition, absolute numbers on of CAR+ cells in peripheral blood and PD-1 expression before and after PD-1 inhibitor. (A) Chimeric antigen receptor T (CAR T) product composition and CAR+ cells/mL of blood in patient 1; (B) PD-1 expression on CAR T cells in patient 1; (C) CAR T product composition and CAR+ cells/mL of blood in patient 2; (D) PD-1 expression on CAR T cells in patient 2.
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haematologica | 2021; 106(10)