On Site Manufacture of AntiCD19 CAR-T Cells. Responses in Subjects with Rapidly Progressive Refractory Lymphomas.

Abstract

<h3>Background</h3> Patients (pts) with rapidly progressive lymphoma and urgent need for therapy have worse prognosis and may not be able to receive CAR-T cells. Decreasing apheresis to infusion time can make CAR-T cells available to this patient population. We present the results of a phase I trial using rapid on-site CAR-T manufacture for relapsed/refractory B cell non Hodgkin lymphoma (NHL). <h3>Methods</h3> Adult pts with CD19+ B NHL who failed ≥ 2 lines of therapy were enrolled. Autologous T cells were transduced with a lentiviral vector (Lentigen Technology, Inc) encoding antiCD19 binding motif, CD8 linker and TNFRS19 transmembrane region, and 4-lBB/CD3z costimulatory domains. GMP compliant manufacture was done using CliniMACS Prodigy, in a 12 day culture. Dose escalation was done using 3+3 design, with 3 dose levels (0.5, 1 and 2 × 10⁶ CAR-T cells/kg). Lymphodepletion was done with cyclophosphamide (60mg/kg × 1) and fludarabine (25mg/m²/d × 3). <h3>Results</h3> As of September 30, 2019, 14 pts were enrolled and treated. Table 1 lists baseline characteristics. 12 pts had refractory NHL, 6 had bulky disease and 9 had symptomatic disease at the time of lymphocyte collection. CAR-T cell product manufacture was successful in all pts. Median transduction rate was 48% [range 29-62] with median culture expansion of 41-fold [range 30-79]. All pts received their infusion of antiCD19 CAR-T cells. CAR-T cell doses were 0.5 × 10⁶/kg (n = 4) and 1 × 10⁶/kg (n = 10). Median apheresis to infusion time was 13 days [range 13–20]. CAR-T persistence, based on vector sequence, peaked in peripheral blood MNCs between days 14-21. All evaluable subjects had persistent CAR-Ts on PCR measurements done on days 30, 60 and 90. CAR-T cell dose did not have an impact in the time to peak <i>in vivo</i> CAR-T cell expansion or in the rate of CAR-T cell persistence (fig 1). Six pts experienced CRS. Five pts had grade 1 – 2 CRS and 1 pt died on day 8 due to CRS. Two pts presented grade 4 CRES, resolved after corticosteroids. No other grade ≥3 non-hematologic toxicity was observed. The most common non – hematologic toxicity was fatigue (n=7). Hematologic toxicity was common, with grade ≥ 3 neutropenia observed in all pts. Among 12 evaluable pts, 8 have achieved complete response (CR) and two had partial response (PR). Two pts did not respond. The CR rate was 67% and overall response rate was 83%. Three pts have died, causes of death include progressive disease (n=2) and CRS (n=1). After a median follow up 4.5 months (range 1 – 14) all responding pts are alive; 1 pt relapsed 6 months after treatment with CD19+ disease and entered CR after antiCD19 antibody drug immunoconjugate. <h3>Conclusions</h3> AntiCD19 CAR-T cells with TNFRS19 transmembrane domain have potent clinical activity. The short manufacture times achieved by local CAR-T cell manufacture enables treatment of a very high risk NHL population that would otherwise not be able to receive CAR-T products due to rapidly progressive disease.