Results from the ongoing phase 1/2 ATALANTA-1 trial (CTIS: 2022-502661-23-00; NCT06561425) indicate that GLPG5101, a novel CD19-targeted chimeric antigen receptor (CAR) T-cell therapy, demonstrated a manageable safety profile and notable efficacy results in patients with relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL) including mantle cell lymphoma (MCL).1,2
Results from the MCL cohort were announced at the 2025 ASH Annual Meeting by Marie Jose Kersten, MD, PhD, professor of hematology at Amsterdam UMC, on December 7, 2025.1 Previous results were published in Blood on November 5, 2024.2
The therapy showed high and durable antitumor activity across the studied NHL subtypes. In the R/R MCL patient cohort (n = 24), at 9.1 months’ median follow-up, all the patients achieved an overall response, and the complete response (CR) rate was 95.8%.1
The therapy is distinguished by its use of a fresh, stem-like, early memory T-cell phenotype and a rapid, decentralized manufacturing platform that enables a 7-day vein-to-vein time.
Efficacy was evaluated in 42 patients who had reached the first response assessment. The objective response rate (ORR) was 88% (n = 37/42).2 The CR rate was 83% (n = 35/42). Of 11 responding patients in phase 1 of the study, 10 had an ongoing response at the data cutoff and 1 patient completed the study while in CR. In phase 2 of the study, all 21 patients had an ongoing response at the data cut off. Of the total patients, 4 (3 with diffuse large B-cell lymphoma [DLBCL] and 1 with MCL) experienced progression after achieving an initial response.
GLPG5101 demonstrated robust expansion in the body across all tested dose levels and disease indications. Persistent CAR T-cells were detected in peripheral blood for up to 21 months post-infusion, indicating long-term durability.
Minimal residual disease (MRD) negativity in plasma was achieved in 12 of 15 (80%) evaluable patients who had achieved a CR. Crucially, all 11 MRD-negative patients with a minimum of 6 months follow-up remained in ongoing CR at the time of data cut off, linking deep molecular remission to durable clinical benefit.
In the R/R MCL cohort, 90% (n = 9/10) of MRD-evaluable patients were MRD-negative at CR. Additionally, 7 of the 9 MRD-negative patients remained in CR at the time of the data cut off.1
Safety Profile of GLPG5101
GLPG5101 demonstrated a manageable safety profile with low incidence of high-grade toxicities in the MCL cohort. The reported data reflects treatment-emergent adverse events (TEAEs) reported up to 14 weeks post-infusion.
In phases 1 and 2, any grade cytokine release syndrome (CRS) occurred in 9 vs 10 patients. Grade 3 or higher CRS occurred in 1 vs 0 patients. Any grade immune effector cell–associated neurotoxicity syndrome (ICANS) occurred in 6 vs 4 patients, and grade 3 or higher ICANS occurred in 0 vs 1 patients.
The most frequently reported TEAEs of grade 3 or higher were hematologic. Out of 49 infused patients, 2 died during the treatment period and 1 died during follow-up.
Study Design and Patient Characteristics
This is an ongoing phase 1/2 study designed to evaluate the safety and efficacy of GLPG5101.
The primary objectives of phases 1 and 2 are to establish the safety, determine the recommended phase 2 dose, and to evaluate the efficacy of GLPG5101. The secondary objectives are to assess manufacturing feasibility, further safety parameters, and additional efficacy metrics such as duration of response and MRD.
The ATALANTA-1 trial enrolled heavily pretreated adult patients with various subtypes of R/R NHL. Patients had a median of 2 prior systemic therapies. Eligible indications included DLBCL, MCL, follicular lymphoma, marginal zone lymphoma, Burkitt lymphoma, and primary central nervous system lymphoma.
In the MCL cohort, the median age of patients in phase 1 was 66.5 years (range, 25–78), and 67 years (range, 40–81) in phase 2. The median range of prior therapies between both phases was 2.5 (range, 1–7) vs 3 (range, 2–11). The majority of patients had received prior Bruton tyrosine kinase inhibitor.1
As of the data cutoff, 53 patients had undergone leukapheresis, 49 received an infusion, and 47 of the 49 patients received fresh product. In the R/R MCL cohort, 25 patients received CAR T-cell infusion, with 24 patients receiving fresh product.
A 7-day vein-to-vein time was successfully achieved in 43 of the 47 patients (91%) who received the fresh product. In the R/R MCL cohort specifically, 23 of 24 patients achieved a 7-day vein-to-vein time. Short vein-to-vein time eliminated the need for cytotoxic bridging therapy for all patients who received a fresh product.
The final product demonstrated significant enrichment of desired T-cell phenotypes compared to the starting material. The proportion of early T-cell phenotypes (naive/stem cell memory and central memory) was significantly increased in both CD4+ and CD8+ CAR T cells. A median increase in the CD4:CD8 ratio of CAR+ T cells was observed in the final product.
The interim results from the ATALANTA-1 study provide strong evidence for the potential of GLPG5101 as a novel CAR T-cell therapy for R/R NHL. The rapid, 7-day vein-to-vein manufacturing time is a significant logistical advantage that can accelerate access to treatment for patients with urgent clinical needs..
“In conclusion, in the ATALANTA-1 study, we saw deep and durable responses in patients with MCL, including patients with high-risk features, of course with relatively short follow-up,” concluded Kersten during the presentation.1 “And we saw…a 96% CR in patients with high-risk disease and a duration of response at 9 months of 83%. We have a very favorable safety profile, no grade 3 or higher CRS and only 1 patient with grade 3 ICANS. We would feel very comfortable even in [patients with MCL] to deliver this therapy on an outpatient basis…All in all, we think this product should be further developed.”