Timing of anti-PD-L1 antibody initiation affects efficacy/toxicity of CD19 CAR T-cell therapy for large B-cell lymphoma

Abstract

More than half of the patients treated with CD19-targeted chimeric antigen receptor (CAR) T-cell immunotherapy for large B-cell lymphoma (LBCL) do not achieve durable remission, which may be partly due to PD-1/PD-L1-associated CAR T-cell dysfunction. We report data from a phase 1 clinical trial (NCT02706405), in which adults with LBCL were treated with autologous CD19 CAR T cells (JCAR014) combined with escalating doses of the anti-PD-L1 monoclonal antibody, durvalumab, starting either before or after CAR T-cell infusion. The addition of durvalumab to JCAR014 was safe and not associated with increased autoimmune or immune effector cell-associated toxicities. Patients who started durvalumab before JCAR014 infusion had later onset and shorter duration of cytokine release syndrome and inferior efficacy, which was associated with slower accumulation of CAR T cells and lower concentrations of inflammatory cytokines in the blood. Initiation of durvalumab before JCAR014 infusion resulted in an early increase in soluble PD-L1 (sPD-L1) levels that coincided with the timing of maximal CAR T-cell accumulation in the blood. In vitro, sPD-L1 induced dose-dependent suppression of CAR T-cell effector function, which could contribute to inferior efficacy observed in patients who received durvalumab before JCAR014. Despite the lack of efficacy improvement and similar CAR T-cell kinetics early after infusion, ongoing durvalumab therapy after JCAR014 was associated with re-expansion of CAR T cells in the blood, late regression of CD19+ and CD19- tumors, and enhanced duration of response. Our results indicate that the timing of initiation of PD-L1 blockade is a key variable that affects outcomes after CD19 CAR T-cell immunotherapy for adults with LBCL.

Graphical abstract

Figure 1.

Best response rate at 3 months. (A) Best response at 3 months on 26 of the 29 patients included in the efficacy-evaluable set according to disease histology (DLBCL NOS; tDLBCL; and HGBL with MYC and BCL2 and/or BCL6 rearrangements) and in the whole cohort. (B) Subgroup analysis of the ORR for key baseline and clinical covariates. ∗Indicates double expressor excluding double- or triple-hit lymphoma (total of 23 patients). † indicates cell of origin by the Hans algorithm. ‡ indicates the sum of the product of the perpendicular diameters of up to 6 target measurable nodes and extranodal sites. § indicates the maximum standardized uptake value in target lesion. The 95% CI was calculated with the use of the Wilson/Brown method. ECOG PS, Eastern Cooperative Oncology Group performance score; HGBL, high-grade B-cell lymphoma; IPI, International Prognostic Index; LDH, lactate dehydrogenase; NOS, not otherwise specified; SPD, sum of the product of the perpendicular diameters of up to 6 target measurable nodes and extranodal sites; tDLBCL, DLBCL transformed from indolent histology.

Figure 2.

CAR T-cell kinetics in patients treated with JCAR014 with and without durvalumab. (A) CAR T-cell counts in the blood by qPCR in groups 1 and 2 (NCT02706405) and JCAR014 alone (NCT01865617) cohorts. Each thin line represents a single patient; bold lines represent the averaged data using local polynomial regression (LOESS) curve fitting approximation with the standard error in gray. (B) Time to CAR T-cell peak counts in the blood by qPCR in groups 1 and 2 (NCT02706405) and the JCAR014 alone (NCT01865617) cohorts. Mann-Whitney tests were used to compare differences between the groups.

Figure 3.

Serum biomarkers in patients treated with JCAR014 with and without durvalumab. AUC_0-28/D0 after CAR T-cell infusion of serum IFN-γ (A), macrophage inflammatory protein-1β (MIP-1β) (B), and sPD-L1 (C) according to the treatment group. (D) Serum sPD-L1 peak concentration after CAR T-cell infusion according to treatment group. (E) Serum sPD-L1 in the JCAR014 in combination with durvalumab (groups 1 and 2; NCT02706405) and JCAR014 alone cohorts (NCT01865617). (F) Serum sPD-L1 and CAR T-cell counts in the blood by qPCR in the JCAR014 in combination with durvalumab (groups 1 and 2; NCT02706405) and JCAR014 alone cohorts (NCT01865617). (E-F) Each thin line represents a single patient, and each dot represents a sample; bold lines represent the averaged data using LOESS curve fitting approximation. Mann-Whitney tests were used to compare differences between groups.

Figure 4.

sPD-L1 inhibits CAR T-cell cytokine production in vitro in a dose-dependent manner. Human CD19 CAR T cells were generated from healthy donors (n = 3) and assayed on days 14 to 16 after the start of manufacturing. CD4⁺ CAR T cells were cocultured with CD19-expressing K562 cells at a 1:1 effector-to-target ratio and the indicated sPD-L1 concentrations or media alone for ∼24 hours. (A) The percentages of CD4⁺ CAR T cells expressing the indicated numbers of cytokines were measured by intracellular flow cytometry. IFN-γ (B) and IL-2 (C) individual production. Data are representative of at least 2 independent experiments. Figures show mean ± standard error of the mean. One-way analysis of variance tests with Tukey correction for multiple comparisons were used to compare differences between groups. IL-2, interleukin-2; ns, not significant.

Figure 5.

DOR in patients treated with JCAR014 with and without durvalumab. Kaplan-Meier estimates of the DOR according to treatment cohort. P value per log-rank test. The numbers of patients at risk at 10-month intervals are indicated.

Figure 6.

CAR T-cell progenitor exhausted phenotype and in vivo re-expansion in the blood with repeated dosing of durvalumab after JCAR014. (A) Aliquots of the infusion products (n = 26) and blood collected after CAR T-cell infusion (expansion, n = 26; contraction, n = 21; day 28, n = 12) were analyzed by flow cytometry. Percentage of PD-1⁺, TCF-1⁺, and PD-1⁺TCF-1⁺ CD3⁺ CAR T cells at each timepoint are shown. Figures show mean ± standard error of the mean. (B) CAR T-cell counts in the blood by qPCR in patients treated with JCAR014 in combination with durvalumab who experienced in vivo re-expansion of CAR T cells. Arrowheads on the x-axis indicate the time of durvalumab doses. Arrows show re-expansion events. Horizontal dashed lines show the qPCR assay limit of detection.

Figure 7.

Tumor burden stabilization/regression and late conversion to CR with repeated dosing of durvalumab after JCAR014. (A) Spider plot of the change in the sum of the product of the perpendicular diameters of ≤6 target measurable nodes and extranodal sites (SPD) over time compared with the baseline prelymphodepletion according to best response at 3 months. ∗ represents patients with extranodal disease and no measurable target lesion. ‡ represents patients who converted to CR at 1 year. PET/CT (B) and immunohistochemistry (C) images at different timepoints in a patient with late conversion to CR with continued durvalumab despite evidence of CD19^– escape. Images were taken at original magnification ×40.