Chow, Victor A.

We report correlative circulating tumor DNA (ctDNA) analyses from TRANSFORM (ClinicalTrials.gov identifier: NCT03575351 ) evaluating lisocabtagene maraleucel (liso-cel) versus standard of care (salvage immunochemotherapy, high-dose chemotherapy, autologous stem cell transplantation [ASCT]) in second-line large B-cell lymphoma (LBCL). ctDNA association with efficacy was investigated at predefined time points (random assignment, day 43, day 64, and day 126 [3 months after liso-cel, approximately 2 months after ASCT]) for 136 patients using ultrasensitive PhasED-Seq. ctDNA clearance (measurable residual disease [MRD] neg ) predicted longer event-free survival (EFS) at all time points in both arms, with significantly more liso-cel–treated patients achieving MRD neg . Liso-cel demonstrated superior outcomes versus ASCT, including longer EFS, progression-free survival (PFS), and duration of response among patients in complete response (CR) and MRD neg . ctDNA re-emergence in patients with CR after ASCT confirmed its potential in predicting relapse. MRD neg remained significantly associated with EFS after adjusting for positron emission tomography (PET) response, while interaction testing revealed a significant interaction between PET status and treatment arm for EFS. Liso-cel achieved deeper, more durable molecular clearance by ctDNA, consistent with superior EFS and PFS versus ASCT for second-line LBCL treatment. ctDNA-MRD provided prognostic value beyond PET, supporting its role as a complementary biomarker for treatment response and relapse prediction.

We report 3-year follow-up results from TRANSFORM comparing lisocabtagene maraleucel (liso-cel) versus standard of care (SOC) for second-line primary refractory/early relapsed (≤12 months) large B-cell lymphoma (LBCL). Adults eligible for autologous stem cell transplantation (N = 184) were randomly assigned 1:1 to liso-cel (100 × 10 6 chimeric antigen receptor–positive T cells) or SOC. Results are reported descriptively. With a median follow-up of 33.9 months, median (95% CI) event-free survival was 29.5 months (9.5 to not reached [NR]) for liso-cel versus 2.4 months (2.2 to 4.9) for SOC (hazard ratio [HR], 0.375; 95% CI, 0.259 to 0.542). Median progression-free survival was NR (12.6-NR) for liso-cel versus 6.2 months (4.3-8.6) for SOC (HR, 0.422; 95% CI, 0.279 to 0.639) with 36-month rates of 51% versus 26.5%. Median overall survival (OS) was NR for both arms (HR, 0.757; 95% CI, 0.481 to 1.191), with 66% of patients crossing over to receive liso-cel; 36-month OS rate was 63% for liso-cel versus 52% for SOC. OS HR (0.566 [95% CI, 0.359 to 0.895]) favored liso-cel when accounting for the treatment effect of crossover. Safety results were consistent with previous reports. At 3-year follow-up, liso-cel confirmed superior, more durable efficacy versus SOC with a favorable safety profile and no new safety signals. These data support liso-cel as an effective second-line treatment with curative potential for relapsed/refractory LBCL.

Background: ctDNA clearance after frontline DLBCL tx has shown strong prognostic value for favorable outcomes, with the potential to improve MRD-driven therapeutic strategies and establish MRD as a surrogate endpoint in future studies (Roschewski M, et al. Blood 2022; Goldstein J, et al. Blood 2023). However, further study is needed to evaluate the association of this noninvasive approach with efficacy outcomes after 2L LBCL tx. We previously reported ctDNA analysis after liso-cel infusion in TRANSFORM (NCT03575351; Stepan L, et al. Blood 2023;142[suppl 1]). Here, we describe the predictive value of pre-tx and on-tx ctDNA levels for durable clinical benefit (CR and event-free survival [EFS]) in both liso-cel and SOC arms from TRANSFORM (Kamdar M, et al. J Clin Oncol 2024), evaluating ctDNA as an earlier surrogate for conventional clinical outcomes. Methods: Baseline (prerandomization) and longitudinal ctDNA levels were assessed in randomized pts treated with liso-cel or SOC in TRANSFORM using the phased variant enrichment and detection sequencing assay (PhasED-Seq; Foresight Diagnostics). Phased variants were identified from baseline plasma samples for longitudinal ctDNA monitoring at multiple on-tx time points, as previously described (Stepan L, et al. Blood 2023;142[suppl 1]). Randomization was defined as study Day 1. Association of ctDNA levels with response per independent review committee using Lugano 2014 criteria and EFS was investigated at various predefined time points, including Day 43 (after 2 cycles of salvage immunochemotherapy for SOC; Day 15 after liso-cel infusion), Day 64 (after 3 cycles of salvage immunochemotherapy for SOC; 1 month after liso-cel infusion), and Day 126 (within 2 months after ASCT; 3 months after liso-cel infusion). To assess the surrogacy value of ctDNA, ctDNA-MRD dynamics and ctDNA clearance were investigated within both arms. Results: In pooled analyses combining the liso-cel and SOC arms, higher baseline ctDNA levels (above the median) were associated with shorter EFS (P = 0.05). Pts achieving Day 126 CR had substantial reductions in ctDNA burden vs baseline, while pts with PD or stable disease had persistently high ctDNA levels vs baseline. Achieving undetectable ctDNA at different time points was associated with significantly longer EFS in pooled analyses, observed as early as study visit Day 43, with the strongest association at Day 126. HR (95% CI) for inferior EFS was 3.0 (1.6-5.7) at Day 43, 3.8 (2.1-7.0) at Day 64, and 4.2 (2.3-7.7) at Day 126 in pts with detectable vs undetectable ctDNA. In the analysis by tx arm, consistent with the pooled analyses, ctDNA clearance was associated with EFS benefit at all measured time points with either liso-cel or SOC. Significantly more pts achieved undetectable ctDNA with liso-cel vs SOC during the study (39/63 [62%] vs 25/65 [38%], respectively; P = 0.013), consistent with superior EFS (primary endpoint) with liso-cel in TRANSFORM. All pts in the SOC arm with evaluable ctDNA at Day 126 (n = 28) had received high-dose chemotherapy (HDCT)/ASCT. However, pts with undetectable ctDNA in the liso-cel vs SOC arm had longer EFS at all predefined time points and had statistically longer EFS at Day 126 (SOC vs liso-cel: HR, 3.9 [95% CI, 1.4-10.6]), indicating a deeper and more durable response with liso-cel vs SOC. In pts with CR, ctDNA showed significant predictive value beyond the response assessment at all time points in the liso-cel arm with a HR (95% CI) of 3.8 (1.3-11.0) at Day 64 and 7.0 (2.0-24.3) at Day 126 for EFS in pts with detectable ctDNA vs undetectable ctDNA. Among pts in the SOC arm who experienced subsequent PD despite achieving CR (all received HDCT/ASCT) and undetectable ctDNA at Day 126, serial ctDNA assessment showed consistent reversion to detectable ctDNA at later time points. Conclusions: ctDNA data from TRANSFORM confirm the value of ctDNA as a biomarker for disease burden monitoring and early prediction of durable clinical benefit after 2L LBCL treatment. Furthermore, longitudinal ctDNA molecular response results agree with previously reported clinical efficacy data and confirm the superiority of liso-cel with deeper responses over the historical SOC in 2L LBCL. ctDNA may have a key role as a surrogate endpoint in future LBCL studies, including after CAR T cell therapies.

7013 Background: Liso-cel is an autologous, CD19-directed, 4-1BB CAR T cell product. In prespecified interim and primary analyses of TRANSFORM (NCT03575351), liso-cel showed significant improvements in efficacy vs SOC in pts with R/R LBCL. Here we report results after ~3-y FU. Methods: TRANSFORM is a randomized phase 3 study comparing liso-cel vs SOC (CT [R-DHAP, R-ICE, or R-GDP] then high-dose CT [HDCT] + ASCT) in adults aged ≤ 75 y with LBCL primary refractory to or relapsed ≤ 12 mo after first-line therapy and eligible for ASCT. Liso-cel arm pts underwent lymphodepletion followed by liso-cel (100 × 10 6 CAR + T cells). Bridging therapy was allowed. SOC arm pts received 3 cycles of CT; responding pts proceeded to HDCT + ASCT. Crossover to receive liso-cel was allowed for SOC arm pts if criteria were met. The primary endpoint was event-free survival (EFS) per independent review committee (IRC). Key secondary endpoints included CR rate and PFS per IRC, and OS. Endpoints were not statistically retested and are reported descriptively. Results: In total, 184 pts were randomized (92 per arm); baseline characteristics were reported (Abramson et al. Blood 2023). Median (range) FU was 33.9 mo (0.9–53.0). Median EFS, PFS, and duration of response (DOR) were longer for liso-cel vs SOC, similar to the primary analysis (Table). A total of 61 (66%) SOC arm pts crossed over to receive liso-cel. Median OS was not reached (NR) in either arm; 36-mo OS rates were numerically higher for liso-cel. Of 76 total deaths (liso-cel, n = 34; SOC, n = 42 [crossover pts, n = 33]), 10 occurred since the primary analysis (liso-cel, n = 6; SOC, n = 4 [all crossover pts]); most were due to disease progression or complications (n = 6). Safety results were consistent with the primary analysis. Cellular kinetics and B-cell aplasia will be presented. Conclusions: After median FU of 33.9 mo, liso-cel as 2L treatment in pts with primary refractory or early relapsed LBCL resulted in deepening of response and continued improvement in efficacy endpoints over SOC, confirming the ongoing benefit of liso-cel. Clinical trial information: NCT03575351 . [Table: see text]