Universal: An Allogeneic First-in-Human Study of the Anti-Bcma ALLO-715 and the Anti-CD52 ALLO-647 in Relapsed/Refractory Multiple Myeloma

Background

Allogeneic (off the shelf) chimeric antigen receptor (CAR) T cell therapy addresses the logistical challenges, availability and variable product quality of autologous CAR T therapy. ALLO-715 is a genetically modified anti-BCMA AlloCAR T^tm cell product in which the TCR alpha constant gene is disrupted to reduce the risk of graft-versus-host disease (GvHD) and the CD52 gene is disrupted with Talen® technology to permit the use of ALLO-647, an anti-CD52 mAb, for selective and prolonged host lymphodepletion (LD).

Methods

This is an open-label, Phase 1 trial (NCT04093596) in adults with R/R multiple myeloma who have received ≥3 prior lines of therapy including a proteasome inhibitor, immunomodulator, and anti-CD38 mAb. Patients (pts) must be refractory to their last treatment line. Patients receive LD followed by ALLO-715 at 1 of 4 dose levels (DL) in a 3+3 dose escalation design: 40, 160, 320, and 480 x 10⁶ CAR+ T cells. Several LD regimens are being evaluated. These include: FCA (fludarabine (F) 90 mg/m², cyclophosphamide (C) 900 mg/m², and ALLO-647 (A) 39 mg divided over 3 days), FCA+ (same F and C but ALLO-647 (A+) dose of 90 mg divided over 3 days); as well as CA (same C and A divided over 3 days, but no F given).

Results

As of 08 July 2020, 19 pts had enrolled and 15 had received ALLO-715 at 3 DLs: 3 pts at DL1 (3 FCA and 0 CA); 7 pts at DL2 (4 FCA and 3 CA); 5 pts at DL3 (3 FCA and 2 CA). As of the data cutoff, no pts had received FCA+ or ALLO-715 DL4. Patients were heavily pre-treated and in advanced stage of disease with a median of 5 (range 3-11) prior lines of therapy and 31.6% ISS Stage III at screening. All but 1 had a prior autologous stem cell transplant. 52.6% (10/19) of patients had high risk cytogenetics, and 26.3% (5/19) had extramedullary disease. The most common Grade ≥3 adverse events were anemia (41.2%), neutropenia (41.2%), lymphopenia (29.4%), and thrombocytopenia (29.4%). Four episodes of Grade ≥3 infections occurred in 4 pts. Three of these were Grade 3 and included parvovirus B19, staphylococcal bacteremia, and pneumonia, which resolved with treatment. The fourth was a Grade 5 episode that occurred on day 8 post-ALLO-715 infusion in a rapidly progressing, refractory myeloma pt who, on day 1, developed a non-neutropenic fever and multifocal pneumonia with negative blood and sputum cultures. The patient progressed to respiratory failure and only comfort care was pursued. This death was considered related to conditioning (CA). No DLTs to ALLO-715 had been reported as of the data cutoff. In addition, no neurotoxicity (ICANS) or GvHD had been reported as of the data cutoff. Cytokine release syndrome was reported in 4 pts (24%). Three episodes were Grade 1 and 1 was Grade 2 (Lee Grading); all resolved without tocilizumab or corticosteroids. Fifteen pts were efficacy evaluable (defined as receiving ALLO-715, and undergoing at least one response assessment or discontinuing prior to the first response assessment), with a median follow-up of 2 months (range 0, 10 months). A higher dose of ALLO-715 (DL3) was associated with greater anti-cancer activity with 3/5 pts responding per IMWG (60%, 95% CI 14.7, 94.7). In pts who received DL3 FCA, 2/3 responded (1 sCR and 1 VGPR, Table 1). All DL3 pts who responded experienced at least a VGPR and achieved MRD negative status by local MRD testing. All responses were initially observed at day 14. Four (80%) out of the 5 responders were still in response at the time of the data cutoff. ALLO-715 cell expansion by qPCR was observed at all dose levels.

Conclusions

These early data suggest that ALLO-715 and ALLO-647 have a manageable safety profile. ALLO-715 shows evidence of clinical activity in the allogeneic setting in pts with R/R multiple myeloma and suggests that higher cell doses are associated with greater anti-cancer activity. Enrollment is ongoing in cohorts with higher ALLO-715 (480M CAR+ T-cells) and ALLO-647 (90mg). Updated safety, efficacy, PK/PD data will be presented. Clinical trial information: NCT04093596.