Zamtocabtagene autoleucel: dual CD20-CD19 targeting for NHL

In this issue of Blood Advances, Balke-Want et al¹ report the results of a phase 1 study that evaluated zamtocabtagene autoleucel (zamto-cel) for relapsed/refractory (R/R) non-Hodgkin lymphomas (NHLs). Chimeric antigen receptor T-cell (CAR-T) therapy has transformed the treatment landscape for B-cell NHL, yet relapse after CD19-directed CAR-T therapy remains problematic. The efficacy of CD19 CAR-T therapy is limited by both tumor-intrinsic factors, such as target antigen modulation that leads to CD19-negative relapse,¹ and by T-cell–intrinsic factors, such as diminished expansion, exhaustion, and lack of central memory and naïve T-cell phenotypes.² Zamto-cel, an autologous anti–CD20-CD19 tandem CAR-T product that is rapidly produced using fresh T cells, challenges both of these shortcomings.

Zamto-cel is an autologous anti–CD20-CD19 tandem CAR-T product with a 4-1BB costimulatory domain that activates via an OR logic-gate. In this study, zamto-cel was manufactured using the fully automated, closed-loop CliniMACS Prodigy system, obviating the need for cryopreservation and leading to a median vein-to-vein time of 14 days (range, 13-14 days). Twelve patients with R/R NHLs were enrolled with 6 patients receiving dose level (DL) 1 (1 × 10⁶ cells per kg) and 6 receiving DL2 (2.5 × 10⁶ cells per kg). For DL1, patients with a variety of NHL histologies were enrolled, whereas for DL2, enrollment was restricted to patients with diffuse large B-cell lymphoma (DLBCL) who relapsed after 1 line of therapy and who were ineligible for autologous stem cell transplantation (ASCT). CAR-T therapy–mediated toxicities were infrequent and low grade; there were no cases of grade ≥3 cytokine release syndrome, and only 1 patient developed reversible immune effector cell associated neurotoxicity syndrome. In terms of efficacy, the best overall response was achieved in 50% of patients who received DL1 and in 100% of patients who received DL2. Durable responses were observed with 3-year progression free survival rates of 66.7% (95% confidence interval [CI], 19.5-90.4) and 33.3% (95% CI, 4.6-67.6) at DL1 and DL2, respectively.

To investigate the mechanism of zamto-cel activity, the authors performed detailed correlative studies. Zamto-cel maximal expansion in vivo was not different between the DLs but was significantly higher in complete responders (CRs) than in non-CRs (mean C_max, 1092.5 vs 111.3 cells per μL). Immunophenotypic analysis of the zamto-cel drug products (DPs) revealed low expression of exhaustion markers, such as programmed cell death protein-1 and lymphocyte activation gene 3, and relative but nonsignificant increases in CD27 and CD127/interleukin-7R on CD8⁺ CAR-Ts. To evaluate the phenotypic consequence of the increases in these cell markers, the authors performed single-cell RNA sequencing on CAR⁺CD27⁺CD127⁺ cells in the zamto-cel DPs. They found increased expression of genes related to protein biosynthesis and of KLF2, which regulates the migration of naïve T cells. In contrast, these cells exhibited lower transcription levels of genes related to cell division, suggesting that this CD27⁺CD127⁺ immunophenotype represented central memory T cells (T_cm). Indeed, the authors found that the T_cm CD8⁺ and CD4⁺ T cells were relatively enriched in the DP of CRs when compared with that of non-CRs and that these T_cm exhibited greater persistence in patients who achieved CR than in those who achieved non-CR.

This phase 1 clinical trial is the second to show a favorable safety and efficacy signal with zamto-cel at the recommended phase 2 dose (2.5 × 10⁶ cells per kg) using fresh, noncryopreserved autologous T cells.³ Although this study and the previously published phase 1 trial by Shah et al used a similar manufacturing system, Shah et al used a point-of-care CAR-T manufacturing strategy, whereas manufacturing for the current trial was performed centrally.³ Reassuringly, zamto-cel performed similarly across the 2 trials. Taken together, these data provide the rationale for 2 ongoing phase 2 pivotal trials, namely DALY2-US (zamto-cel DL2 as third line in R/R DLBCL, ClinicalTrials.gov identifier: NCT04792489) and DALY2-EU (zamto-cel DL2 as second line in R/R DLBCL and ASCT-ineligible, ClinicalTrials.gov identifier: NCT04844866).

Although these data strengthen the evidence for zamto-cel as a novel CAR-T product for the treatment of NHL, several questions remain. First, the authors propose that dual targeting of CD19 and CD20 may limit CD19 modulation as a mechanism of post–CAR-T therapy immune escape. However, previous experience with bispecific CAR-T constructs suggests that achieving robust, simultaneous engagement of both antigens is not guaranteed.⁴ Although all patients had CD20 expression at baseline and 10 of the 12 patients expressed CD19, the extent to which zamto-cel effectively targets both antigens or prevents antigen-loss relapse was not reported and must be evaluated in future studies. A clue may be gleaned from a recently presented preplanned interim analysis of DALY2-US that showed that a few of the patients who relapsed following zamto-cel had target antigen loss.⁵ Second, although the authors postulated that their manufacturing approach yielded products with improved phenotypic characteristics, their small sample size precluded definitive conclusions. Nonetheless, the vein-to-vein time of 14 days compares favorably with commercially available CAR-T products, which typically range from 30 to 48 days.⁶ With the results of DALY2-US and DALY2-EU forthcoming, we will likely soon know the answers to these questions and, importantly, whether the early promise of zamto-cel will be realized.

Conflict-of-interest disclosure: L.S.M. reports serving as an advisor for Kite-Gilead, Autolus, and Incyte; receiving consultation fees from Kite-Gilead and Autolus; and receiving research funding from Kite-Gilead, Vor, Wugen, and Autolus. H.K.S. declares no competing financial interests.