Adaptive Manufacturing of LV20.19 CAR T-Cells for Relapsed, Refractory Mantle Cell Lymphoma

Introduction:

Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy characterized by the presence of t(11;14) and bright CD20 expression. Approved CD19 CAR T-cell therapy for relapsed/refractory (R/R) MCL is limited by both relapse and high rates of Grade 3+ cytokine release syndrome (CRS) and ICANS with 15% and 31% patients (pts) experiencing such toxicities, respectively. To improve outcomes we utilized dual targeted lentiviral anti-CD20/anti-CD19 (LV20.19) CAR T-cells with an adaptive manufacturing (MF) process to optimize the final CAR product as part of a Phase 1/2 clinical trial in R/R MCL.

Methods:

We conducted a Phase 1/2 single center, prospective trial (NCT04186520) evaluating LV20.19 CAR T-cells at a fixed dose of 2.5x10e6 cells/kg for pts with R/R B-cell non-Hodgkin Lymphoma. We report results of MCL pts from a fully enrolled Phase I safety run-in and Phase II efficacy cohort. The primary outcome for the Phase II cohort was day 90 complete response (CR) rate. The Phase II cohort utilized an adaptive 8/12 day MF process to enhance the percentages of T-SCM (stem cell-like memory) and T-CM (central memory) CAR T-cells in the final product by shortening culture time. CAR T-cells were harvested either on day 8 of MF or extended to a 12-day MF process depending on achieving target cell dose in culture. Fludarabine/cyclophosphamide lymphodepletion was started during MF to facilitate fresh infusion in eligible pts. Descriptive statistics were utilized for demographic data and the Kaplan Meier methodology for survival analysis.

Results:

In total 17 pts with R/R MCL received LV20.19 CAR T-cells (Phase 1=3 pts and Phase 2=14 patients). All pts achieved target cell dose. 13 pts received an 8-day product while 4 received a 12-day product. 14/17 pts received a fresh (non-cryopreserved) infusion. 8-day products were enriched for T-SCM/CM phenotype cells with significantly lower number of terminally differentiated effector memory (EMRA) T-cells in the CD4 compartment (p<0.05) than 12-day products.

The median age was 63 (50-74 years) and 15 (88%) were cisgender male. The median number of lines of therapy was 4 (3-8). p53 deletions or mutation were present in 7 pts. Day 28 overall response rate (ORR) was 100%; CR rate=76% and partial response (PR) =24%. Initial ClonoSEQ MRD assay performed within the first 90 days of LV20.19 CAR T (n=13) was negative in 10 pts (77%). Among Phase II patients with day 90 results available (n=12) the ORR was 100%, CR rate=92% and PR rate=8% exceeding the Phase II efficacy threshold. Two pts have relapsed to date, +8 months and +2 years after infusion. There were two non-relapse mortality (NRM) events that occurred beyond day 28: gram negative rod sepsis & COVID19 infection resulting in a 1-year NRM rate of 12%. The 1-year progression free survival (PFS) was 77%, 1-year duration of response (DOR) was 92%, and 1-year overall survival (OS) of 84%. Median PFS/DOR/OS have not been met with median follow-up of 14 months of surviving pts (Figure 1).

In terms of safety, 94% (n=16) experienced CRS, all grade 1-2. 18% (n=3) had ICANS in the first 28-days, 2 pts with Grade 3 toxicity. There were two pts with late (>day 28) episodes of Grade 1 neurological toxicity. Both pts had immense expansion of lymphocytes in the CSF (total nucleated cell count of 386/µLand 1005/µL) with CAR+ T cells present. Both received only a single dose of intrathecal hydrocortisone (no systemic steroids) with resolution of neurotoxicity within 24 hours of administration.

Conclusions:

Bispecific LV20.19 CAR T-cells with adaptive MF process is feasible, safe, and efficacious for R/R MCL with ORR 100%, no Grade 3+ CRS and low rates of Grade 3+ ICANS (12%). Adaptive MF enriched the final product with higher percentages of T-SCM/T-CM CAR cells and allowed most pts to receive CAR-T cells within 8 days of apheresis. Dual targeting of CD20 and CD19 with CAR-T cells may improve outcomes in pts with relapsed, refractory MCL.