A novel dual-targeted chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable efficacy in patients with relapsed or refractory mantle cell lymphoma (MCL), according to results from a single-center phase I/II study conducted at the Medical College of Wisconsin.
The investigational therapy, which targets both CD20 and CD19 antigens (LV20.19), achieved an unprecedented 100% objective response rate among all 17 treated patients, with 15 patients (88%) achieving complete responses. These findings, recently published in the Journal of Clinical Oncology, suggest a potentially significant advancement in the treatment landscape for this challenging hematologic malignancy.
Innovative Manufacturing Approach
A distinctive feature of this study was the on-site, adaptive manufacturing process using CliniMACS Prodigy, which produced the CAR T-cell product in just 8 to 12 days. This approach was specifically designed to optimize the final product for increased numbers of naive and stem cell memory-like T cells, potentially enhancing efficacy.
"Dual targeting in mantle cell lymphoma, a disease characterized by bright CD20 expression, may have potential benefits based on this clinical trial," explained Dr. Nirav N. Shah, associate professor of medicine at Medical College of Wisconsin and corresponding author of the study. "We're excited to learn more by expanding on this single center clinical trial with an ongoing multicenter trial that's actively enrolling."
Impressive Durability of Response
The therapy demonstrated remarkable durability, with a median duration of response not reached at the time of analysis. At one year, the response durability rate was 93%, with only two patients experiencing relapse at 8 and 24 months, respectively.
At a median follow-up of 15.8 months, the one-year progression-free survival rate was 80% (95% CI = 49%–93%), and the one-year overall survival rate was 86% (95% CI = 55%–96%). Additionally, 79% of evaluable patients showed no minimal residual disease at a median follow-up of 96 days.
Favorable Safety Profile
The safety profile appears promising compared to existing CAR T-cell therapies for MCL. Cytokine release syndrome (CRS) occurred in 94% of patients but was exclusively grade 1 or 2 in severity, requiring no intensive interventions.
Immune effector cell-associated neurotoxicity syndrome (ICANS) was observed in only three patients (18%) within 28 days of treatment, with grade 3 events in two patients that were successfully resolved. This compares favorably to approved therapies like brexucabtagene autoleucel (Tecartus), which has reported rates of grade 3 or worse CRS in approximately 15% of patients and grade 3 or worse ICANS in 31%.
"I would say that the toxicity profile of this is similar to lisocabtagene maraleucel," noted Dr. Shah, referring to another approved CAR T-cell therapy with a more favorable safety profile but typically lower efficacy in MCL.
Three non-relapse mortality events were reported, all occurring in the context of ongoing B-cell aplasia and related to infectious complications.
Clinical Context and Unmet Need
Mantle cell lymphoma represents a challenging B-cell malignancy with a 5-year relative survival rate of only 55.6%. While two CD19-directed CAR T-cell therapies—brexucabtagene autoleucel and lisocabtagene maraleucel—are currently approved for relapsed/refractory MCL, both have limitations.
"Biologically, mantle cell is a CD20 bright lymphoma, leading us to hypothesize that targeting both CD19, which we know is an effective target in CAR-T, and CD20, which is effectively harnessed with other types of drugs, could lead to better outcomes," Dr. Shah explained.
The dual-targeting approach may address some limitations of existing therapies. Lisocabtagene maraleucel offers a better safety profile but demonstrates lower response rates and a median progression-free survival of only 15.3 months. Brexucabtagene autoleucel shows higher efficacy but with significantly more toxicity concerns.
Study Design and Patient Population
The trial enrolled 17 patients with a median age of 63 years (range 50-74 years), predominantly male (88%), who had failed at least two previous lines of therapy (median of four prior therapies, range 2-8) or relapsed after transplantation.
Following lymphodepletion, patients received a single dose of LV20.19 CAR T cells at 2.5 x 10^6 cells/kg. The primary endpoint was the 3-month complete response rate, with secondary endpoints including overall response rate, duration of remission, minimal residual disease status, safety outcomes, progression-free survival, and overall survival.
Future Directions
Based on these promising results, a multicenter phase II investigation is currently underway, aiming to enroll approximately 70 patients with mantle cell lymphoma within a year.
"We still don't have a good understanding as to why CAR-T was so successful in some, and why others relapsed," Dr. Shah acknowledged. "The other big thing is [that] this looks good in a single-center study. We're very experienced with this CAR-T and so it is important to evaluate in a multicenter fashion, which we have initiated as part of the DALY II USA clinical trial."
The researchers are also exploring applications of this dual-targeting approach in other B-cell malignancies, including chronic lymphocytic leukemia, diffuse large B-cell lymphoma, marginal zone lymphoma, and follicular lymphoma.
"By targeting CD20 and CD19, you really open yourself up to almost any malignancy in lymphoma. CD20 is the most ubiquitous target out there in lymphoma," Dr. Shah noted. "We focused initially on DLBCL and mantle because those are ones where there's a clear clinical indication for CAR-T, but we hope to continue to develop this for other B cell malignancies, as well."
The investigators concluded that on-site adaptive manufactured LV20.19 CAR T cells are feasible, safe, and highly efficacious for relapsed/refractory mantle cell lymphoma, with an exceptional response rate and favorable safety profile that warrants further investigation in larger, multicenter studies.
