Refractory Follicular Lymphoma Research Articles

457 A Phase I Trial of Tazemetostat and Venetoclax in Relapsed and Refractory non-Hodgkin Lymphoma

OBJECTIVES/GOALS: Primary Objective: To evaluate the safety of venetoclax plus tazemetostat in patients with relapsed and refractory (R/R) Follicular lymphoma (FL) or Diffuse large B-cell lymphoma (DLBCL) Secondary Objectives: 1. To evaluate the tolerability of the combination of T+V using patient reported outcomes (PROs) 2. To evaluate the efficacy of T+V METHODS/STUDY POPULATION: Study design: A phase I trial in two parts: Part 1: a single-arm, open-label sequential dose escalation (3+3) of venetoclax in combination with tazemetostat, given at its recommended phase II dose (RP2D) of 800mg BID, to determine the maximum tolerated dose (MTD) of venetoclax. Part 2: two expansion cohorts (R/R DLBCL and R/R FL) to further characterize the safety and tolerability of the combination, and to estimate the preliminary efficacy. We will perform additional exploratory studies to determine if there are biologic features that correlate with responses. Eligibility: up to 38 patients aged >/=18 years old with histologically confirmed diagnosis of FL or DLBCL who have received at least 2 prior lines of therapy for lymphoma with evidence of disease progression and meet inclusion criteria RESULTS/ANTICIPATED RESULTS: Primary Endpoints: 1. Incidence and severity of adverse events as per CTCAEv5 2. Dose-limiting toxicity (DLT) of T+V, and to establish the maximum tolerated dose (MTD) of V plus fixed dose T Secondary Endpoints: 1. Incidence and Severity of toxicity and quality of life as per PRO-CTCAE and FACT-Lym 2. Overall response rate (ORR), complete response (CR) rate, partial response (PR) rate, as per Lugano criteria 3. Duration of response (DOR), progression-free survival (PFS), overall survival (OS)Exploratory Endpoints: 1. Characterization of tumor cells pre-treatment (including EZH2 mutations and BCL2 translocations) 2. Phenotypic analysis (including BCL2 expression) and quantification of the tumor microenvironment in pre-treatment samples (using image mass cytometry)Explorato DISCUSSION/SIGNIFICANCE: There is a need for novel therapeutic approaches to improve the prognosis for patients with R/R NHL. Preclinical data suggests synergism between the pair.5 Importantly, this represents a chemotherapy-free, oral regimen. If well tolerated, this could present an alternative therapeutic option for patients ineligible for more intensive therapies.

Investigator choice of standard therapy versus sequential novel therapy arms in the treatment of relapsed follicular lymphoma (REFRACT): study protocol for a multi-centre, open-label, randomised, phase II platform trial

BackgroundRelapsed or refractory follicular lymphoma (rrFL) is an incurable disease associated with shorter remissions and survival after each line of standard therapy. Many promising novel, chemotherapy-free therapies are in development, but few are licensed as their role in current treatment pathways is poorly defined.MethodsThe REFRACT trial is an investigator-initiated, UK National Cancer Research Institute, open-label, multi-centre, randomised phase II platform trial aimed at accelerating clinical development of novel therapies by addressing evidence gaps. The first of the three sequential novel therapy arms is epcoritamab plus lenalidomide, to be compared with investigator choice standard therapy (ICT). Patients aged 18 years or older with biopsy proven relapsed or refractory CD20 positive, grade 1-3a follicular lymphoma and assessable disease by PET-CT are eligible. The primary outcome is complete metabolic response by PET-CT at 24 weeks using the Deauville 5-point scale and Lugano 2014 criteria. Secondary outcomes include overall metabolic response, progression-free survival, overall survival, duration of response, and quality of life assessed by EQ-5D-5 L and FACT-Lym. The trial employs an innovative Bayesian design with a target sample size of 284 patients: 95 in the ICT arm and 189 in the novel therapy arms.DiscussionWhilst there are many promising novel drugs in early clinical development for rrFL, understanding the relative efficacy and safety of these agents, and their place in modern treatment pathways, is limited by a lack of randomised trials and dearth of published outcomes for standard regimens to act as historic controls. Therefore, the aim of REFRACT is to provide an efficient platform to evaluate novel agents against standard therapies for rrFL. The adaptive Bayesian power prior methodology design will minimise patient numbers and accelerate trial delivery.Trial registrationClinicalTrials.gov: NCT05848765; 08-May-2023.EudraCT2022-000677-75; 10-Feb-2022.

Budget Impact of Introducing Fixed-Duration Mosunetuzumab for the Treatment of Relapsed or Refractory Follicular Lymphoma After Two or More Lines of Systemic Therapy in the USA.

This study aimed to assess the budget impact of introducing fixed-duration mosunetuzumab as a treatment option for adult patients with relapsed or refractory follicular lymphoma after at least two prior systemic therapies and to estimate the total cumulative costs per patient in the USA. A 3-year budget impact model was developed for a hypothetical 1-million-member cohort enrolled in a mixed commercial/Medicare health plan. Comparators were: axicabtagene ciloleucel, tisagenlecleucel, tazemetostat, rituximab plus lenalidomide, copanlisib, and older therapies (rituximab or obinutuzumab ± chemotherapy). Costs per patient comprised treatment-associated costs including the drug, its administration, adverse events, and routine care. Dosing and safety data were ascertained from respective package inserts and clinical trial data. Drug costs (March 2023) were estimated based on the average wholesale acquisition cost reported in AnalySource®, and all other costs were based on published sources and inflated to 2022 US dollars. Market shares were obtained from Genentech internal projections and expert opinion. Budget impact outcomes were presented on a per-member per-month basis. Compared with a scenario without mosunetuzumab, its introduction over 3 years resulted in a budget increase of $69,812 (1% increase) and an average per-member per-month budget impact of $0.0019. Among the newer therapies, mosunetuzumab had the second-lowest cumulative per patient cost (mosunetuzumab = $202,039; axicabtagene ciloleucel = $505,845; tisagenlecleucel = $476,293; rituximab plus lenalidomide = $263,520; tazemetostat = $250,665; copanlisib = $127,293) and drug costs, and its introduction only increased total drug costs by 0.1%. By year 3, the cumulative difference in the per patient cost with mosunetuzumab was -$303,805 versus axicabtagene ciloleucel, -$274,254 versus tisagenlecleucel, -$61,481 versus rituximab plus lenalidomide, -$48,625 versus tazemetostat, and $74,747 versus copanlisib. Older therapies were less costly with 3-year cumulative costs that ranged from $36,512 to $147,885. Over 3 years, the estimated cumulative per patient cost of mosunetuzumab is lower than most available newer therapies, resulting in a small increase in the budget after its formulary adoption for the treatment of relapsed or refractory follicular lymphoma.

Deep and Durable Responses with Epcoritamab SC Monotherapy in Patients with Relapsed or Refractory Follicular Lymphoma: Data from the Epcore NHL-1 Follicular Lymphoma Dose-Expansion Cohort

Deep and Durable Responses with Epcoritamab SC Monotherapy in Patients with Relapsed or Refractory Follicular Lymphoma: Data from the Epcore NHL-1 Follicular Lymphoma Dose-Expansion Cohort

Comparative efficacy and safety of tisagenlecleucel and axicabtagene ciloleucel among adults with r/r follicular lymphoma

Regulatory approvals of tisagenlecleucel (tisa-cel) and axicabtagene ciloleucel (axi-cel) have established the feasibility of chimeric antigen receptor T-cell therapies for the treatment of adults with relapsed or refractory follicular lymphoma (r/r FL). This study used individual patient data from ELARA (tisa-cel) and aggregate published patient data from ZUMA-5 (axi-cel) to compare efficacy and safety outcomes in r/r FL using matching-adjusted indirect comparison methods. After adjustment for baseline differences in the trial populations, the results suggested that tisa-cel (n = 52), compared with axi-cel (n = 86), had similar effects on overall response rate (91.2% vs. 94.2%; p = .58), complete response rate (74.0% vs. 79.1%; p = .60), progression-free survival (HR [95% CI]: 0.8 [0.4, 1.9]; p = .67), and overall survival (HR [95% CI]: 0.5 [0.2, 1.5]; p = .21). Tisa-cel (n = 53) was associated with better safety outcomes than axi-cel (n = 124), reflected by lower rates of any grade and grade ≥3 cytokine release syndrome and neurological events.

EE536 Cost-Effectiveness of Axicabtagene Ciloleucel (axi-cel) Vs Standard of Care for Adult Patients with Relapsed or Refractory Follicular Lymphoma as 4TH or Later Line Treatment in Sweden

EE536 Cost-Effectiveness of Axicabtagene Ciloleucel (axi-cel) Vs Standard of Care for Adult Patients with Relapsed or Refractory Follicular Lymphoma as 4TH or Later Line Treatment in Sweden

HTA83 Economic Evaluations in Relapsed or Refractory (R/R) Follicular Lymphoma (FL): Challenges for Health Technology Assessment (HTA) Submissions

HTA83 Economic Evaluations in Relapsed or Refractory (R/R) Follicular Lymphoma (FL): Challenges for Health Technology Assessment (HTA) Submissions

Matching-adjusted indirect comparison from the Lymphoma Epidemiology of Outcomes Consortium for Real World Evidence (LEO CReWE) study to a clinical trial of mosunetuzumab in relapsed or refractory follicular lymphoma.

Mosunetuzumab is a novel bispecific antibody targeting epitopes on CD3 on T cells and CD20 on B cells with the goal of inducing T-cell mediated elimination of malignant B cells. A recent pivotal phase I/II clinical trial (GO29781) demonstrated that mosunetuzumab induced an overall response rate of 80%, complete response rate of 60%, and a median progression-free survival of 17.9 months in patients with relapsed/refractory (r/r) follicular lymphoma (FL) following at least two prior lines of systemic therapy, including alkylator and anti-CD20 antibody-based therapy. Historical data from cohorts receiving therapy for r/r FL can provide some context for interpretation of single-arm trials. We compared the results from the mosunetuzumab trial to outcomes from a cohort of patients with r/r FL from the LEO Consortium for Real World Evidence (LEO CReWE). We applied clinical trial eligibility criteria to the LEO CReWE cohort and utilized matching-adjusted indirect comparison weighting to balance the clinical characteristics of the LEO CReWE cohort with those from the mosunetuzumab trial. Overall response rates (73%, 95% CI:65-80%) and complete response rates (53%, 95% CI:45-61%) observed in the weighted LEO CReWE cohort were lower than those reported on the mosunetuzumab trial (ORR=80%, 95% CI:70-88%; CR=60%, 95% CI:49-70% respectively). Progression-free survival at 12 months was similar in the weighted LEO CReWE (60%, 95% CI:51-69%) and the mosunetuzumab trial (PFS 58%, 95% CI:47-68%). Sensitivity analyses examining the impact of matching variables, selection of line of therapy, and application of eligibility criteria, provide context for best practices in this setting.

Comparative Effectiveness of Axicabtagene Ciloleucel Vs Historical Standard-of-Care in Patients with Relapsed or Refractory Follicular Lymphoma: An Analysis of CIBMTR and SCHOLAR-5 Data

Background: Axicabtagene ciloleucel (axi-cel), an autologous chimeric antigen receptor (CAR) T-cell therapy, achieved an overall response rate (ORR) of 94% and a complete response (CR) rate of 79% in patients with relapsed or refractory (r/r) follicular lymphoma (FL) after two or more prior lines of therapy in the ZUMA-5 trial ( Jacobson et al. Lancet Oncol. 2022). Since its FDA approval in March 2021, there has been little evidence on comparative effectiveness (CE) studies of axi-cel vs standard-of-care (SoC), except ones using ZUMA-5 and historical SCHOLAR-5 data (eg, Ghione et al. Blood. 2022). This study was aimed to address this evidence gap in CE of axi-cel vs SoC used to treat r/r FL in real-world settings. Methods: The two data sources in this study were patients who received commercial axi-cel between March 2021 and May 2023 from the CIBMTR and patients who received historical SoC (eg, chemotherapy, anti-CD20 mAb + chemotherapy, immunomodulatory imide drugs) between July 2014 and December 2020 from SCHOLAR-5, which served as an external control of ZUMA-5 trial. The index date was defined as the initiation date of either the infusion for axi-cel patients or the last eligible systemic therapy for SoC patients. Patients were included if they were age ≥ 18, had documented r/r FL with histological grade 1, 2 or 3a, and received at least 2 prior lines of therapy at the index. Patients were excluded if they had transformed diffused large B-cell lymphoma, central nervous system involvement, prior receipt of CAR T or other non-CAR T cellular therapies or allogeneic stem cell transplant, or no post-index information on outcomes. Four effectiveness outcomes were ORR, CR rate, progression-free survival (PFS), and overall survival (OS). Imbalance in observed prognostic risk factors between the two was adjusted via a propensity score analysis using the standard mortality ratio weighting (SMRW). The primary analyses included weighted univariable analysis and multivariable logistic (ORR and CR rate) or Cox (PFS and OS) regressions that were adjusted for the covariates after the SMRW. A sub-analysis of patients age ≥ 65 was conducted using the same methods as the primary analyses. Results: The unweighted study cohort included 376 patients, in which 256 (68%) received axi-cel . Thepatients who received axi-cel were more likely to be younger (median age 61 for axi-cel vs 67 for SoC), have grade 3a FL (37% vs 12%), received 3 or more prior lines of therapy (83% vs 58%), or remained refractory to the last prior therapy (79% vs 73%) vs those who received SoC. The imbalance in the observed prognostic risk factors was mitigated via the SMRW. The weighted univariable analysis, in which the sample size by treatment reflected the SMRW, is shown in Table 1. In patients of all ages, ORR was 92% in axi-cel vs 67% in SoC, and CR rate was 84% vs 37%. Because of varying follow-up lengths by treatment (median 7 months for axi-cel and 37 months for SoC), survival outcomes were reported at month 6, at which time PFS rate was 88% in axi-cel vs 64% in SoC and OS rate was 97% vs 85%. The corresponding proportions for patients age ≥ 65 were similar to those reported for patients of all ages. In the weighted multivariable regressions, axi-cel was associated with statistically significantly better outcomes by all 4 effectiveness measures vs SoC (Table 1). Specifically, in patients of all ages, the odds ratios for axi-cel were 4.93 (95% CI, 2.35−10.34) for ORR and 16.72 (95% CI, 7.03−39.73) for CR rate, and the hazard ratios for axi-cel were 0.41 (95% CI, 0.22−0.77) for PFS and 0.15 (95% CI, 0.06−0.34) for OS. Similar to the patients of all ages in the primary analyses, patients age ≥ 65 in the sub-analysis also demonstrated improved outcomes associated with axi-cel (Figure 1). Conclusions: This study showed that patients with r/r FL after two or more prior lines of therapy treated with axi-cel experienced better outcomes compared with patients treated with SoC, and that older patients also benefited significantly from axi-cel. These findings suggest that axi-cel addresses an important unmet medical need in patients with r/r FL. Future research should include longer follow-up data on outcomes of axi-cel and CE of axi-cel vs other contemporary SoC therapies.

Dose Adjustments of Linperlisib in Relapsed or Refractory Follicular Lymphoma: A Post-Hoc Analysis of a Pivotal Phase II Study

Background: The oral PI3Kδ inhibitor linperlisib has proven to be a significant therapeutic option for patients with relapsed or refractory follicular lymphoma (FL) in a phase II study. As a result, linperlisib was approved in China for the management of adult patients with relapsed or refractory FL who had undergone at least two prior systemic treatments. In addition to linperlisib, several PI3K inhibitors were approved by Food and Drug Administration for relapsed or refractory FL. Despite their confirmed efficacy, these drugs encountered substantial tolerability issues, leading to the rescission from indications for FL. In response to these challenges, we undertook a post-hoc analysis of the phase II linperlisib study to evaluate its safety profile in treating FL, as well as assessing the impact of dose adjustments on prognosis of patients. Methods: In the single-arm, open-label, multicenter phase II study, eligible patients (adults with histologically confirmed relapsed or refractory FL showing disease progression post at least two prior systemic therapies) were administered daily doses of 80mg linperlisib until disease progression or the emergence of unacceptable toxicity. The primary endpoint was the objective response rate (ORR). For this post-hoc analysis, patients were stratified into three groups: the dose-adjusted group (patients who had dose adjusted or interrupted due to adverse events [AEs]); the treatment-terminated group (patients who ceased treatment for a variety of reasons, which included AEs, withdrawal of informed consent, and the investigator's judgment); and the dose-unadjusted group (patients who experienced neither dose adjustment nor interruption). Results: Of 84 patients in the study, dose adjustments or interruptions due to AEs were required for 26 patients, while 34 patients terminated their treatment (15 due to AEs, 6 as per the investigator's discretion, and 14 due to withdrawal of informed consent). A remaining subset of 24 patients experienced no dose modifications. Notably, the dose-adjusted and treatment-terminated groups contained more patients aged 60 and above (19.2% and 29.4% respectively), compared to only 4.2% in the dose-unadjusted group. Other baseline characteristics appeared comparable across all three groups. Among 26 patients in the dose-adjusted group, 25 had dose adjustments due to AEs, and 11 experienced dose interruptions. Infectious pneumonia and interstitial pneumonia were reported in 20.2% (17 cases) and 4.8% (4 cases) of patients, and represent the primary AEs causing treatment termination (9 cases and 4 cases, respectively). Thirteen patients experienced diarrhea during the study, with six requiring dose adjustments, and one patient ceasing treatment due to autoimmune colitis combined with a fungal infection. Rashes, which had an incidence of 11.9% (10 cases), necessitated dose interruptions in four patients but did not require any dose reductions. The ORR was comparable among the three groups (84.6% in dose-adjusted group, 79.4% in treatment-terminated group, and 75.0% in dose-unadjusted group). However, the dose-adjusted and dose-unadjusted groups demonstrated superior duration of response (median DOR, 15.9 months in dose-adjusted group, 9.7 months in treatment-terminated group, and 14.8 months in dose-unadjusted group) and progression-free survival (median PFS, 19.4 months in dose-adjusted group, 11.5 months in treatment-terminated group, and 16.6 months in dose-unadjusted group) than the treatment-terminated group (Figure 1). The median overall survival was not reached in three groups. Conclusion: Our post-hoc analysis reveals that elderly patients (≥60 years old) have reduced tolerance to linperlisib, necessitating more frequent dose adjustments due to AEs. Notably, treatment discontinuation results in inferior DOR and PFS, while dose adjustments or suspensions yield comparable DOR and PFS to full-dose treatment, suggesting that tolerability-guided dose modification effectively reduces AEs without sacrificing therapeutic efficacy.

Maintenance of Moderate to High Levels of Functioning and Quality of Life with Odronextamab Monotherapy in Patients with Relapsed or Refractory Follicular Lymphoma

Background: Goals of patient-centered care for management of relapsed or refractory follicular lymphoma (R/R FL) are to improve clinical outcomes while maintaining or improving health-related quality of life (HRQoL). In ELM-2 (NCT03888105), a Phase 2, open-label, multicohort, multicenter study, odronextamab monotherapy demonstrated high and durable complete response rates and generally manageable safety in patients with R/R FL. We report here, for the first time, patient-reported outcome (PRO) results from ELM-2 in patients with R/R FL. Methods: Patients with R/R FL Grade 1-3a received odronextamab IV at 80 mg weekly in 21-day cycles in Cycles (C) 1-4. Optimization of the step-up regimen to mitigate cytokine release syndrome (CRS) was reported previously. Odronextamab was administered with steroid prophylaxis and step-up doses of 0.7/4/20 mg in C1, then 80 mg on Days 1, 8, and 15 of C2-4. After C4, odronextamab maintenance continued at 160 mg every 2 weeks until disease progression or unacceptable toxicity. Patients with durable complete response (≥9 months) switched to dosing every 4 weeks. Patients completed EORTC QLQ-C30, FACT-Lym, and EQ-5D-3L questionnaires at Weeks 1 (baseline), 2, 3, 4, and 10, then every 8 weeks for the remainder of the first year and every 12 weeks in the second year. Results here focus on six key PRO scales: EORTC QLQ-C30 Global Health Status/Quality of Life (GHS/QOL), physical functioning (PF), role functioning (RF), and fatigue; FACT-Lym lymphoma subscale (LymS); and EQ-5D-3L visual analog score (VAS). Longitudinal analyses using mixed models for repeated measures (MMRM) were conducted through Week 50 (the last visit with ≥10 patients with PRO data). Changes from baseline were considered statistically significant if the 95% confidence interval did not contain zero. No adjustment for multiplicity was performed, hence all statistical significance is nominal. Published ranges for minimum important difference (MID) to define clinically meaningful changes are: EORTC QLQ-C30 scales, 10 points; FACT-Lym LymS, 2.9-5.4 points; and EQ-5D-3L VAS, 7-12 points. For responder and time to definitive deterioration (TTDD) analyses, the upper end of these published MID ranges was used to define deterioration or improvement. Results: At the ELM-2 interim data cutoff on 31-Jan-2023, 140 patients with R/R FL Grade 1-3a had received at least 1 dose of odronextamab. Median age was 60.5 years (range: 22-84), with 38.6% ≥65 years, 52.9% male, 57.1% White, 32.1% Asian, 52.2% ECOG=0, and 47.1% ECOG=1. Median duration of follow-up was 26.6 months (range: 6.2-37.5). PRO completion rates for EORTC-QLQ-C30, FACT-Lym, and EQ-5D-3L were high at baseline and remained high for all assessments through Week 50. At baseline, moderate levels of general health (GHS/QoL) and high levels of functioning (PF and RF) were observed that were higher (better) than reference values for general cancer or non-Hodgkin's Lymphoma (NHL). Fatigue scores at baseline were lower (less symptoms) than reference values for general cancer or NHL. EORTC QLQ-C30 GHS/QOL, PF, RF, and fatigue scores were maintained from baseline through Week 50 (Table). For EQ-5D-3L VAS, the overall estimated mean changes from baseline improved statistically significantly but did not reach MID thresholds (Table). For FACT-Lym LymS, overall estimated mean change from baseline statistically significantly improved, and scores improved statistically significantly from Weeks 10 to 42 (except Week 34), with clinically meaningful improvements at Weeks 26 and 42 (Figure). The proportion of patients reporting meaningful improvement or stability across the six scales was higher than the proportion reporting meaningful worsening through Week 50 (Table). The median TTDD for EORTC-QLQ-C30 GHS/QoL was 22.41 (95% CI: 14.59 to not yet reached) months, corresponding to the median PFS. Median TTDD was not reached for EORTC QLQ-C30 PF, FACT-Lym LymS, and EQ-5D-3L VAS scales. Conclusions: For patients with R/R FL, patient-reported HRQoL results were favorable during odronextamab treatment until disease progression, with no detriments on patient-reported symptoms, functioning, and overall quality of life. These results complement encouraging clinical efficacy, durability of responses, and tolerability observed in this highly refractory patient population and support the future role of odronextamab in the management of patients with R/R FL.

EPCORE FL-1: Phase 3 Trial of Subcutaneous Epcoritamab with Rituximab and Lenalidomide (R 2) Vs R 2 Alone in Patients with Relapsed or Refractory Follicular Lymphoma

Background: Follicular lymphoma (FL) is the most common form of indolent non-Hodgkin lymphoma (NHL). Several treatment options are approved by the US Food and Drug Administration for second- or later-line FL therapy, including rituximab + lenalidomide (R 2). However, advanced-stage FL remains incurable and new treatment options for relapsed or refractory (R/R) disease are needed. Epcoritamab, a subcutaneously administered, bispecific antibody that binds CD3 on T lymphocytes and CD20 on B cells, induces potent and selective T-cell-mediated killing of malignant CD20 + B cells (van der Horst et al, Blood Cancer J 2021). In the first-in-human, phase 1/2 EPCORE NHL-1 trial (NCT03625037) in heavily pretreated patients with B-cell NHL (N=68), epcoritamab showed manageable safety and promising single-agent anti-tumor activity (Hutchings et al, Lancet 2021). Among 10 patients with R/R FL, objective response rate (ORR) was 90% (95% CI: 55-100) and complete response (CR) rate was 50%. In the ongoing phase 1b/2 trial evaluating epcoritamab + R 2 for R/R FL (EPCORE NHL-2 arms 2a and 2b; NCT04663347), ORR was 98% among 104 efficacy-evaluable patients, with a complete metabolic response in 87%. Most cytokine release syndrome (CRS) events were low grade (n=111; grade 1-2, 46%; grade 3, 2%) and occurred in cycle 1; all CRS events resolved with routine management. These encouraging data, and the distinct mechanisms of action of epcoritamab and R 2, support ongoing evaluation of this combination for its potential to improve clinical outcomes in patients with R/R FL. The phase 3 EPCORE FL-1 trial was designed to evaluate epcoritamab in combination with R 2 vs R 2 alone in patients with R/R FL with ≥1 prior line of anti-lymphoma therapy. We present an updated protocol, reflecting recent developments and revisions implemented in this study. Study Design and Methods: EPCORE FL-1 (NCT05409066) is a global, randomized, open-label, multicenter phase 3 trial designed to evaluate efficacy and safety of epcoritamab in combination with R 2 vs R 2 alone in patients with R/R FL. Adult patients must have histologically confirmed classic FL (previously grades 1 to 3a FL) stage II, III, or IV with a CD20 + tumor on a representative biopsy based on local pathology report and no evidence of histologic transformation. Patients must have R/R disease after ≥1 prior anti-lymphoma regimen that contained an anti-CD20 monoclonal antibody in combination with chemotherapy; patients receiving only prior anti-CD20 monoclonal antibody monotherapy and/or radiation are not eligible. Other key eligibility criteria include Eastern Cooperative Oncology Group performance status 0 to 2, fluorodeoxyglucose positron emission tomography-avid disease, and ≥1 measurable disease site per Lugano 2014 criteria. Lenalidomide-refractory FL (best response to lenalidomide of stable or progressive disease or progressive disease within 6 months of completion of lenalidomide) is excluded. Approximately 520 patients will be enrolled and randomized 1:1 to receive a full dose of epcoritamab in combination with R 2 or R 2 alone ( Figure); the trial is currently enrolling in 2 arms, Arms A & C. Based on emerging safety and efficacy data, Arm B has been closed to enrollment and the recommended dose of epcoritamab in combination with R 2 is 48 mg. Epcoritamab will be subcutaneously administered using a step-up dosing regimen to full dose in cycle 1 (28 days/cycle). Full dose of epcoritamab will be administered weekly in cycles 2-3 and monthly from cycle 4 onward for up to 12 cycles of treatment. Patients will be serially assessed for disease progression at prespecified intervals. The primary endpoint is progression-free survival assessed by independent review committee (IRC) per Lugano criteria. Key secondary efficacy endpoints include CR rate (by IRC per Lugano criteria), overall survival, and minimal residual disease negativity. Other efficacy endpoints include best overall response, duration of response, duration of complete response, time to progression, event-free survival, time to next anti-lymphoma treatment, and patient-reported outcomes. Safety endpoints include incidence and severity of treatment-emergent adverse events and adverse events of special interest. Exploratory endpoints include assessments of pharmacodynamic and pharmacokinetic data. The study opened for enrollment in 2022 in North America, South America, Europe, Africa, Asia, and Australia.

An Economic Model to Estimate Costs of Cytokine Release Syndrome and Neurological Events Among Patients Treated with CAR T Cell Therapies for Relapsed or Refractory Follicular Lymphoma

Background: CAR T cell therapies have exhibited promising clinical responses in populations that are traditionally challenging to treat. Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are 2 CAR T cell therapies now available in the United States (US) for the treatment of R/R follicular lymphoma (FL) after 2 or more lines of systemic therapy. Lisocabtagene maraleucel (liso-cel) is currently being investigated in clinical trials for the treatment of patients with R/R second-line high-risk and third line or later FL. As observed in other approved indications, the improved response and survival rates from the introduction of CAR T cell therapies are typically accompanied by the potential for AEs, such as cytokine release syndrome (CRS) and neurological events (NEs). However, the rates and severity of these AEs tend to vary across CAR T cell therapies. Understanding the economic implications of these 3 CAR T cell therapies and their associated AEs is crucial for informed decision-making and to underscore key economic and safety differences across the 3 CAR T cell therapies. The primary objective of this analysis was to estimate the average per-patient weighted costs of CRS and NEs for a patient with R/R FL treated with a CAR T cell therapy (liso-cel, axi-cel, or tisa-cel) based on clinical trial rates. Secondary objectives included estimates for (1) the opportunity cost of treating with axi-cel or tisa-cel versus liso-cel and (2) the additional number of patients eligible for treatment with liso-cel based on a hypothetical sample of 100 treated patients. Methods: An economic model was developed using data from the TRANSCEND FL (NCT04245839; n = 130), ZUMA-5 (NCT03105336; n = 124), and ELARA (NCT03568461; n = 97) studies. CRS and NE rates reported in the FL studies were incorporated in a decision analytic economic model to estimate costs from a health care system perspective in 2023 US dollars. Microcosting analysis data from the TRANSCEND FL study were used as CRS and NE cost inputs; the model assumed that CRS and NE management costs across CAR T cell therapies would not differ. The analysis used a Monte Carlo simulation approach to address uncertainty surrounding the clinical and economic data. The model output was a weighted average that represented cost for the average treated patient, including those with and without CRS and/or NEs. The average per-patient total cost difference between CAR T cell therapies was used to estimate the number of additional patients who could be treated with liso-cel versus axi-cel or tisa-cel. Results: Rates of CRS grade 1‒2/≥ 3 were 56.9/0.8% for liso-cel, 71.8%/6.5% for axi-cel, and 48.5%/0.0% for tisa-cel. Rates of NE grade 1‒2/≥ 3 were 13.1%/2.3% for liso-cel, 41.1%/ 15.3% for axi-cel, and 34.0%/ 3.1% for tisa-cel. The overall per-patient weighted average costs for CRS and NEs were estimated to be $20,626 for liso-cel, $44,096 for axi-cel, and $26,460 for tisa-cel (Figure). The per-patient weighted average cost per CRS event was $14,631 for liso-cel, $21,299 for axi-cel, and $12,456 for tisa-cel. The per-patient weighted average cost per NE was $5994, $22,797, and $14,004 for liso-cel, axi-cel, and tisa-cel, respectively. Total per-patient cost differences for liso-cel compared with axi-cel and tisa-cel were −$23,470 and −$5835, respectively. The resulting opportunity costs from treating 100 patients with liso-cel instead of axi-cel and tisa-cel would allow for the treatment of an additional 5.2 and 1.3 patients, respectively. Conclusions: This economic analysis revealed lower overall per-patient weighted average costs associated with liso-cel compared with axi-cel and tisa-cel, primarily due to lower CRS and NE rates versus axi-cel and lower NE rates versus tisa-cel. In comparison with axi-cel and tisa-cel, liso-cel demonstrated robust economic and clinical value, with lower rates of CRS and/or NEs associated with substantial cost savings per AE event.

Subgroup Analysis from a Phase 2, Single-Arm Trial of the Oral PI3Kδ Inhibitor Linperlisib in Patients with Relapsed or Refractory Follicular Lymphoma

Background In our previous phase 2 trial (NCT04370405), linperlisib, an oral phosphatidylinositol 3-kinase delta (PI3Kδ) inhibitor, demonstrated encouraging activity and manageable safety in adult patients with relapsed/refractory (R/R) follicular lymphoma (FL) who had received at least 2 prior systemic therapies. It's crucial to note that FL patients with bone marrow involvement (BMI) generally present more unfavorable prognosis. Here, we present a subgroup analysis from this phase 2 study, which is specifically focused on BMI at baseline. Methods Details of the trial design and study population have been previously reported. In brief, eligible patients (age > 18 years; histologically confirmed relapsed or refractory FL; disease progression post at least 2 prior systemic therapies) received 80 mg linperlisib tablets daily in a 28-day cycle, until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) assessed by independent review committee (IRC); secondary endpoints included the duration of response (DOR), disease control rate (DCR), progression free survival (PFS), overall survival (OS) and safety profile. For this subgroup analysis, patients were grouped based on the presence or absence of BMI at baseline. For those with baseline BMI, biopsies were evaluated to confirm complete responses. Evaluations of antitumor response were conducted every 2 treatment cycles, following the guidelines of the International Research Working Group. Results As previously reported, 84 patients included in the full analysis set (FAS). By subgroup, 25 had baseline BMI and 59 did not. Baseline characteristics by subgroup are shown in Table 1. In this subgroup analysis, a trend toward higher response rate was seen in R/R FL patients with BMI compared to those without such involvement: ORR based on IRC assessment was 88.0% vs 76.3%; best overall response (BOR) of CR was 24.0% vs 11.9%; BOR of PR was 64.0% vs 64.4%. Patients with BMI had DCR that was consistent with those without BMI (92.0% vs 93.2%). The median DOR and PFS were similar across this subgroup (DOR: 11.7 months vs 13.0 months; PFS: 13.3 months vs 13.7 months) (Table 2). Although the median OS was not reached, 12-month OS rates for patients with and without BMI was 91.7% and 91.5%, respectively (Table 2). Safety was evaluated in all R/R FL patients who had received ≥1 dose of linperlisib. Rates of any-grade treatment-related adverse events (TRAEs) were similar across this subgroup and comparable with the overall population (Table 2). When compared to the overall population, patients without BMI experienced fewer grade ≥3 TRAEs, while a marginally higher incidence of grade ≥3 TRAEs was observed in patients with BMI (Table 2). Conclusions This subgroup analysis indicated that linperlisib is an effective and well-tolerated treatment option for patients with R/R FL, irrespective of BMI. Although minor differences were observed in this subgroup, their significance is limited due to the small sample sizes and probably do not alter the overall clinical benefit of linperlisib. Nevertheless, these findings warrant further investigation.

Mosunetuzumab Monotherapy Continues to Demonstrate Durable Responses in Patients with Relapsed and/or Refractory Follicular Lymphoma after ≥2 Prior Therapies: 3-Year Follow-up from a Pivotal Phase II Study

Background: Mosunetuzumab is a CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells. In a pivotal Phase II study (NCT02500407), mosunetuzumab demonstrated a high complete response (CR) rate with a manageable safety profile in patients with relapsed/refractory (R/R) follicular lymphoma (FL) and ≥2 prior lines of therapy (Budde et al. Lancet Oncol 2022). Mosunetuzumab is a fixed-duration treatment that can be administered in an outpatient setting. Here, we present updated data for patients with R/R FL and ≥2 prior lines of therapy, after 3 years of follow-up. Methods: Eligible patients with R/R FL Grade (Gr) 1-3a and ≥2 prior therapies received intravenous mosunetuzumab in 21-day cycles with step-up dosing in Cycle (C) 1 (C1 Day [D] 1, 1mg; C1D8, 2mg; C1D15/C2D1, 60mg; C3D1 and onwards, 30mg). Hospitalization for treatment was not required. Patients achieving a CR by C8 completed treatment without additional cycles; patients with a partial response or stable disease received a total of 17 cycles. The primary endpoint was CR rate as determined by an Independent Review Committee (as best response; Cheson 2007 criteria). Duration of response (DOR), duration of complete response (DOCR), progression-free survival (PFS), event-free survival (EFS), and safety were secondary endpoints. Time to next treatment (TTNT), response to retreatment, biomarkers of minimal residual disease (MRD), and circulating B-cell counts were exploratory endpoints. Results: Ninety patients with R/R FL were enrolled. As of May 2, 2023, median time on study was 37.4 (range: 2.0-48.0) months. Investigator-assessed best overall response and CR rates were 77.8% (95% CI: 67.8-85.9) and 60.0% (95% CI: 49.1-70.2), respectively. The median DOR was 35.9 months (95% CI: 20.7-not reached [NR]). Median DOCR was NR (95% CI: 33.0-NR); the estimated 30-month DOCR rate was 72.4% (95% CI: 59.2-85.6) ( Table). Three years after the end of treatment, 57.1% of 70 responding patients were alive and disease progression-free. Median PFS was 24.0 months (95% CI: 12.0-NR) ( Figure). The median TTNT was 37.3 months (95% CI: 18.0-NR); estimated EFS at 36 months was 51.8% (95% CI: 40.8-62.8). After initial mosunetuzumab treatment, 34/90 (37.8%) patients had received a new anti-lymphoma therapy, including 33/90 (36.7%) patients who received a new systemic treatment (8/33 [24.2%] of these patients received chimeric antigen receptor T-cell therapy); 8/90 (8.9%) had radiotherapy; 2/90 (2.2%) had excision of tumor; 2/90 (2.2%) had an allogeneic stem cell transplant; and 1/90 (1.1%) had an autologous stem cell transplant. Five patients received retreatment with mosunetuzumab, 3/5 of these patients had a CR. No new cytokine release syndrome (CRS) events, serious, or Gr ≥3 adverse events (AEs) were reported since the previous analysis (median follow-up of 28.3 months; Bartlett et al. ASH 2022). CRS events occurred in 44.4% of patients and 2.2% were Gr 3/4 in severity; all CRS events resolved. Overall AEs and serious AEs were comparable to the previous analysis (Bartlett et al. ASH 2022); febrile neutropenia was not reported. Forty-six (51.1%) patients experienced Gr 3/4 AEs related to mosunetuzumab; the rate of AEs leading to discontinuation was low (4.4%). Peripheral blood B-cell depletion following treatment with mosunetuzumab occurred in all patients, and recovery was observed after a median of 18 months following the end of treatment in patients with a sustained response using follow-up samples. MRD kinetics following mosunetuzumab therapy will be presented. Conclusions: In this updated analysis, with a median follow-up of 37.4 months, durable responses continued to be observed with fixed-duration mosunetuzumab in patients with R/R FL. The manageable safety profile was consistent with previous reports. Evidence of B-cell recovery was observed after a median of 18 months following the end of treatment.

TRANSCEND FL: Phase 2 Study Primary Analysis of Lisocabtagene Maraleucel as Second-Line Therapy in Patients with High-Risk Relapsed or Refractory Follicular Lymphoma

Background: Results with CD19-directed CAR T cell therapy in patients (pts) with second-line (2L) R/R follicular lymphoma (FL) and high-risk features, such as progression of disease within 24 months (POD24) from diagnosis or double refractory to anti-CD20 antibody plus alkylator, have not been previously reported. TRANSCEND FL (NCT04245839), a global, phase 2, open-label, single-arm, multicohort, pivotal study, assessed efficacy and safety of the anti-CD19 CAR T cell therapy lisocabtagene maraleucel (liso-cel) in pts with second line or later (2L+) R/R indolent NHL. Some data from the primary analysis were previously reported, including safety in 2L+ R/R FL, and focused on efficacy in third line or later R/R FL (Morschhauser F, et al. Hematol Oncol 2023;41[S2]:877‒880). Here, we report primary analysis results in the cohort of pts with 2L high-risk R/R FL. Methods: Eligible pts in the 2L R/R FL cohort had biopsy-confirmed FL before enrollment and must have had POD24 with treatment ≤ 6 months from original FL diagnosis and/or must have had high tumor burden as defined by modified Groupe d'Etude des Lymphomes Folliculaires (mGELF) criteria. All pts received 1 prior combination systemic therapy with an anti-CD20 antibody and alkylator. Eligible pts received liso-cel (100 × 10 6 CAR + T cells) after lymphodepleting chemotherapy (LDC). Bridging therapy was allowed with reconfirmation of PET-positive disease before LDC. The primary endpoint was ORR per independent review committee (IRC) by PET/CT using Lugano 2014 criteria. Secondary endpoints included CR rate, duration of response (DOR), PFS, OS, safety, and cellular kinetics. Pharmacodynamic endpoints were exploratory. Results: At data cutoff (January 27, 2023), 23 of 25 leukapheresed pts received liso-cel and were evaluable for safety and efficacy per IRC; 1 received nonconforming product and 1 reached CR after bridging therapy and no longer met eligibility criteria. Median (range) age was 53 y (34-69), 74% had stage III/IV disease, and 35% were high-risk per FL International Prognostic Index (FLIPI). Sixty-five percent of pts had POD24 from initiation of first-line combination chemoimmunotherapy (52% had POD24 from diagnosis), 70% met mGELF criteria (mGELF only, 48%; mGELF and POD24 from diagnosis, 22%), and 48% were double refractory to anti-CD20 antibody plus alkylator. Median (range) on-study follow-up was 18.1 months (1.0-26.8). In efficacy-evaluable pts, the ORR and CR rate were both 95.7% (95% CI, 78.1-99.9; 1-sided P < 0.0001; Table). With a median follow-up of 16.8 months and 17.8 months, respectively, median DOR and PFS were not reached; 12-month DOR and PFS were 89.8% and 91.3%, respectively. The most common grade (gr) ≥ 3 treatment-emergent AEs (TEAE) were cytopenias; neutropenia was most frequent (52%). Cytokine release syndrome (CRS) occurred in 12 (52%) pts (no gr ≥ 3). Median (range) time to onset and resolution of CRS was 6 days (2-9) and 3 days (2-7), respectively. Neurological events (NE) occurred in 4 (17%) pts, with 1 (4%) gr 3 and no gr 4-5 (Table). Median (range) time to onset and resolution of NEs was 8.5 days (6-11) and 2.5 days (1-4), respectively. Three (13%) pts received tocilizumab/steroids for CRS/NEs. Prolonged cytopenia (gr ≥ 3 laboratory values at Day 29) occurred in 3 (13%) pts; all recovered to gr ≤ 2 by Day 90. No gr ≥ 3 infections were reported. One TEAE death occurred in the context of IRC-assessed disease progression due to gr 5 macrophage activation syndrome (MAS). Liso-cel showed rapid expansion with median (range) time to maximum transgene levels of 10 days (7-11). Persistence of liso-cel transgene was detected up to Month 12 in 5 of 18 (28%) pts. B-cell aplasia (< 3% CD19 + B cells in peripheral blood lymphocytes) after liso-cel infusion was rapid and maintained in ≥ 95% of pts through Month 2. Conclusions: This is the first report of outcomes in 2L high-risk R/R FL with CD19-directed CAR T cell therapy. In this population, liso-cel achieved very high CR rates (22 of 23 pts); deep and durable remissions, with follow-up ongoing; and a favorable safety profile with low rates of severe (gr ≥ 3) CRS, NEs, and prolonged cytopenia, and no severe infections. These data support liso-cel as a potential new treatment option in pts with 2L R/R FL at high-risk for treatment failure.

Epcoritamab SC Monotherapy Leads to Deep and Durable Responses in Patients with Relapsed or Refractory Follicular Lymphoma: First Data Disclosure from the Epcore NHL-1 Follicular Lymphoma Dose-Expansion Cohort

Background: Despite recent therapeutic advances, an unmet need exists for efficacious, well-tolerated, and convenient treatment (tx) options for patients (pts) with relapsed/refractory (R/R) follicular lymphoma (FL). In particular, pts with high-risk disease, including those refractory to both anti-CD20 tx and an alkylating agent (double refractory) and those with disease progression within 2 y of first-line (1L) immunochemotherapy (POD24), require more effective options. Epcoritamab, a subcutaneous (SC) CD3xCD20 bispecific antibody, was recently approved by the US FDA for the tx of adults with R/R diffuse large B-cell lymphoma (DLBCL), not otherwise specified, including DLBCL arising from indolent lymphoma, and high-grade B-cell lymphoma after ≥2 lines of systemic tx. Here we present initial results from the FL dose-expansion cohort of the EPCORE™ NHL-1 trial (NCT03625037; phase 1/2). Methods: Pts with CD20 + R/R FL (grade [G] 1-3A) who had received ≥2 prior lines of systemic tx received epcoritamab SC in step-up doses (SUD 1 and 2) in cycle (C) 1, followed by full doses of 48 mg in 28-d Cs: QW, C1-3; Q2W, C4-9; and Q4W, C≥10 until disease progression or unacceptable toxicity. The primary endpoint of overall response rate (ORR) was assessed per Lugano criteria by an independent review committee. As a secondary analysis, minimal residual disease (MRD) was assessed in peripheral blood using the clonoSEQ ® assay (Adaptive Biotechnologies, Seattle, WA). Results: Between Sep 2020 and Oct 2022, 128 pts with R/R FL G1-3A were enrolled to receive epcoritamab SC. As of Apr 21, 2023, the median follow-up was 17.4 mo. Median age was 65 y, 61% of pts had FLIPI 3-5, and 85% had stage III-IV disease. The median number of prior lines of tx was 3 (range, 2-9); 31% of pts had ≥4 prior lines of tx. Common prior therapies included anthracyclines (77%), lenalidomide (31%), and autologous stem cell transplant (19%). Most pts were primary refractory (54%), double refractory (70%), or refractory to their last prior tx (69%); 42% had POD24, and 52% progressed within 2 y of initiating any 1L tx. The ORR was 82%, with a complete response (CR) rate of 63% ( Figure). The median time to response and CR was 1.4 and 1.5 mo, respectively. ORRs/CR rates were generally consistent across prespecified high-risk subgroups: double refractory, 76%/56%; refractory to last prior tx, 74%/51%; POD24, 80%/61%; progression within 2 y of initiating any 1L tx, 79%/64%. High ORRs/CR rates were observed across lines of tx, with a trend of higher rates in earlier lines: 2 prior lines, 89%/72%; 3 prior lines, 88%/68%; ≥4 prior lines, 68%/45%. Median progression-free survival (PFS) was 15.4 mo; median duration of response, duration of CR, and overall survival were not reached. An estimated 85% and 74% of pts with CR remained in response at 12 and 18 mo, respectively. MRD negativity was correlated with improved PFS. The most common tx-emergent AEs (TEAEs) of any grade were CRS (66%), injection-site reaction (57%), COVID-19 (40%), fatigue (30%), neutropenia (28%), diarrhea (27%), and pyrexia (25%). TEAEs leading to tx discontinuation occurred in 19% of pts, the most common being COVID-19. CRS was mostly low grade (40% G1, 25% G2, 2% G3) and primarily occurred following the first full dose (median time to onset after first full dose, 15 h). No CRS events led to tx discontinuation. ICANS was reported in 8 pts (6% overall; 4% G1, 2% G2); all resolved without leading to tx discontinuation. Fatal TEAEs occurred in 13 pts (10%). In a separate R/R FL cohort evaluating an optimized SUD regimen in C1 to mitigate CRS risk, a clinically meaningful reduction in CRS incidence and severity was observed (data to be presented). Conclusions: Single-agent epcoritamab SC resulted in deep and durable responses with high ORR and CR rates in hard-to-treat, high-risk pts with R/R FL. Responses were consistent across subgroups. A correlation between MRD negativity and PFS was observed. The safety profile was manageable; CRS occurrence was predictable, and a reduction in CRS occurrence and severity was seen with an optimized SUD regimen. Overall, no new safety signals were detected. Epcoritamab is currently being investigated in several FL trials across lines of tx, including an ongoing phase 3 trial (NCT05409066) in R/R FL.

Novel CD20 Mutations As a Mechanism of Resistance to CD20-CD3 Targeted Therapies in Non-Hodgkin's Lymphoma

Non-Hodgkin's Lymphoma (NHL) is one of the most common blood cancer types in the world. CD20 is a B cell restricted lineage marker that is a well-established target for the treatment of NHL and anti-CD20 agents are included as in standard of care regimens. Given the success of these targeted therapies, strategies to further enhance therapeutic activity are being explored, including the CD20-CD3 bispecific molecule, mosunetuzumab, which is approved for treatment of relapsed and refractory Follicular Lymphoma in adults who have received >2 lines of treatment. Mosunetuzumab acts by redirecting CD3+ T cells to engage and eliminate CD20-expressing B cells. As with other targeted therapies, mutations and loss of target expression have been described following mosunetuzumab therapy [1]. Here we describe the impact of novel mutations identified in patient biopsy samples from the mosunetuzumab monotherapy trial, GO29781 that were located within the extracellular and transmembrane domains of CD20 on protein expression, localization and T-cell mediated killing. NHL cell lines, SU-DHL-16 and MAVER-1, were engineered using CRISPR-Cas9 system to create CD20 knock out (KO) cell lines. Wild-type (WT) or mutant CD20 were exogenously re-expressed in the CD20 KO cell lines and in the CD20 negative acute lymphoblastic leukemia cell line, REH, to create isogenic cell lines for further analysis. Complete CD20 loss was observed in cells expressing CD20 P160fs (frameshift) and Q187* (truncating) mutations. CD20 missense mutations located in the extracellular domain (C167G, K175E) expressed CD20 protein levels comparable to CD20 WT cells and membrane localization was confirmed by flow cytometry and immunofluorescence microscopy. To test the functional effect of CD20 mutations, in vitro co-culture cell killing assays were carried out using healthy donor CD8+ T cells, isogenic cell lines (3:1 effector to tumor cell ratio) and a proof-of-concept CD20-CD3 bispecific antibody. Differences in T-cell mediated killing were observed across mutation types. CD20 WT cell lines demonstrated 95-99% cell killing following 48 hour treatment while the CD20 KO, frameshift and truncating mutations all showed negligible T-cell mediated killing (~10-17% cell death). Cells expressing the missense mutations in the extracellular domain showed resistance to T-cell mediated killing (~30-45% cell death) compared to CD20 WT cells. T-cell activation was assessed by CD69 (early) and CD25 (late) surface markers. In all co-cultures, the level of CD69+ T cells was equivalent, while the CD69+CD25+ CD8 T cells were only significantly increased in the CD20 WT co-cultures, consistent with the high level of T-cell mediating killing. We have confirmed that these mutations can play a role in the development of resistance through both loss of target protein expression and interference within the anti-CD20 binding site. These studies help to characterize mechanisms of resistance to mosunetuzumab that could be extended to other anti-CD20 targeted agents. [1] Schuster et al. Journal of Clinical Oncology 2022, 40 (16), 7526.

Subcutaneous (SC) Mosunetuzumab (mosun) As First-Line Therapy for Patients (pts) with High Tumor-Burden Follicular Lymphoma (FL): First Results of a Multicenter Phase 2 Study

Introduction: Cytotoxic chemotherapy plus anti-CD20 antibodies is the current standard of care for pts with newly diagnosed high-burden FL. While effective, this approach is burdened by toxicities, including infections and second cancers, and up to 20% of pts progress within 2 years and have poor outcomes. Intravenous (IV) mosun is a CD20xCD3 bispecific antibody recently approved for the treatment of pts with relapsed or refractory FL based on remarkable efficacy data, and its activity may be even greater in chemotherapy-naïve patients. Furthermore, SC mosun proved as effective as, and possibly better tolerated than, the IV formulation while increasing administration efficiency and convenience. Here, we present the first results of a phase 2 multicenter trial of SC mosun in patients with untreated high-burden FL. Methods: Key eligibility criteria included: Age ≥18 years, stage 2-4 FL in need of therapy per GELF criteria, being fit for chemoimmunotherapy, adequate bone marrow and organ function. SC mosun was administered at the dose of 5 mg on D1 and 45 mg on D8 and D15 of C1, and 45 mg on D1 of each subsequent 21-day cycle. Premedication consisted of dexamethasone, diphenhydramine, and acetaminophen before each mosun dose during C1 and on C2D1 if cytokine release syndrome (CRS) occurred in C1. Subjects with ≥3 CRS risk factors (stage 3-4, bulky disease, bone marrow (BM) involvement, elevated LDH) received dexamethasone 10 mg for 3 days with each mosun dose in C1 and C2. Prophylactic hospitalization was not required. Treatment lasted 8 cycles in pts who achieved complete response (CR), and up to 17 in those with partial response. Response was assessed per the Lugano 2014 and LYRIC 2016 criteria. BM evaluation was mandated in pts with baseline BM involvement who achieved radiographic CR. CRS and neurotoxicity were graded per the 2019 ASTCT criteria. Results: Between July 2022 and July 2023, 43 pts were enrolled. Median age was 55 years (range 26-77), 40% of pts had bulky disease (≥7 cm), 25% had grade 3A FL, and 27% had a FLIPI score ≥3. The median SUV max was 11.5 (range 3.7-41.1)(Table). At the cutoff date of 07/21/2023, 4 pts were in screening, 22 were on treatment, and 13 completed treatment. Four pts discontinued therapy early due to progressive disease (1), or adverse events (AE) (3, one related to study drug). Out of 230 patient-cycles administered, 9 (4%) were delayed due to AEs, by a median of 13 days (range 7-17). Among 39 safety-evaluable pts, the most common treatment-emergent AE were injection site reaction (72%, all G1), CRS (51%), fatigue (33%), dry skin (33%), skin rash (26%), ALT elevation (23%), and AST elevation (21%). G≥3 neutropenia occurred in 4 pts (10%), while infections occurred in 10 pts (26%), and were G1-2 in 8 cases and G3 in 2 cases. One pt died of cardiac arrhythmia in the setting of COVID19-associated pneumonia. CRS occurred most commonly after C1D1 and was G1 in 18 pts (90%) and G2 in 2 (10%). Median time to onset of the first CRS episode was 31h (2-91). Hospitalization and tocilizumab were only required in the two pts who experienced G2 CRS. Twenty-six pts were evaluable for response (1 had concurrent neoplasm at first response assessment, 1 had indeterminate response (IR)3 per LYRIC criteria, and 15 are yet to be evaluated). The best overall response rate was 96% and the CR rate was 81%. All 22 CR were seen at the first response assessment (Figure). Similar response rates were observed among higher-risk subgroups, including pts with high-risk FLIPI (figure), grade 3A FL (ORR 100%, CR 75%), bulky disease (ORR 100%, CR 82%), or SUVmax ≥13 (ORR 83%, CR 83%)). At a median follow-up for response-evaluable pts of 6.0 months, 2 pts have experienced progression, one with CD20-negative FL at the end of therapy, the other with DLBCL diagnosed 6 weeks after treatment initiation on a left axillary lymph node with baseline SUV 41 and not previously biopsied. Conclusion: SC mosun demonstrated a manageable safety profile and highly encouraging efficacy in pts with newly diagnosed high-burden FL, including those with higher-risk disease. Assessment of durability of responses will require additional follow-up. Enrollment continues and updated data will be presented.

Matching-Adjusted Indirect Comparison (MAIC) of Efficacy and Safety of Lisocabtagene Maraleucel (liso-cel) and Mosunetuzumab for the Treatment (Tx) of Third Line or Later (3L+) Relapsed or Refractory (R/R) Follicular Lymphoma (FL)

Background:The tx landscape of R/R FL is evolving with the availability of anti-CD19 chimeric antigen receptor (CAR) T cell therapies and CD20xCD3 bispecific T-cell-engaging monoclonal antibodies (mAb). Liso-cel is an autologous, CD19-directed, 4-1BB CAR T cell therapy which recently reported a positive benefit-risk tx profile for the 3L+ tx of patients with R/R FL (Morschhauser F, et al. ICML 2023; LBA4). Mosunetuzumab, a CD20xCD3 bispecific T-cell-engaging mAb, is approved for the tx of R/R FL after 2 or more lines of therapy (LOT). In the absence of head-to-head data, we conducted an unanchored MAIC to compare the efficacy and safety of liso-cel and mosunetuzumab for the 3L+ tx of patients with R/R FL. Methods: Unanchored MAICs were used to estimate population-adjusted relative tx effects between individual patient-level data from TRANSCEND FL (NCT04245839; data as of January 27, 2023; median follow-up of 19.3 months) and aggregate data from GO29781 (NCT02500407; data as of August 27, 2021; median follow-up of 18.3 months; N = 90). For TRANSCEND FL, the leukapheresed (intention to treat [ITT]) set (N = 114) was used for primary comparisons of efficacy endpoints: Progression-free survival (PFS), objective response rate, and complete response rate (all per independent review committee assessment). Overall survival was not analyzed due to the low rate of events. The treated efficacy set (n = 101) was used for a sensitivity analysis of efficacy comparisons. The treated set (n = 107) was used for comparisons of safety endpoints: cytokine release syndrome (CRS), neurological events (NEs), serious infections, and use of corticosteroids or tocilizumab for CRS. Baseline characteristics and outcome measures in TRANSCEND FL were redefined to align with those reported in GO29781. Data from TRANSCEND FL were weighted using a method-of-moments propensity score model to match the marginal distribution (ie, mean, variance) of clinical factors among patients from GO29781. A panel of expert clinicians selected and ranked tx effect modifiers separately for efficacy and safety endpoints. For efficacy, factors adjusted for included number of prior systemic LOTs, progression of disease ≤ 24 months from initiation of immunochemotherapy, bulky disease at screening, FL International Prognostic Index risk factor, refractory to last therapy, double refractory to an anti-CD20 antibody and alkylating agent, ECOG PS at screening, sex, and prior autologous HSCT. For safety, factors adjusted for included age, bulky disease at screening, refractory to last therapy, number of prior systemic LOTs, ECOG PS at screening, Ann Arbor stage, and sex. Hazard ratios (HR) were used to compare PFS, and odds ratios (OR) were used for response rates and safety outcomes. Results: After adjusting for all available factors, when compared with mosunetuzumab, liso-cel was associated with higher objective response rate (OR, 3.78 [95% CI, 1.48‒9.67]), and complete response rate (OR, 6.46 [2.85‒14.65]), and improved PFS (HR, 0.28 [0.16‒0.49]) based on an effective sample size (ESS) of 71.4 (Figure). Results were consistent across all scenario analyses, including unadjusted comparisons and sensitivity analyses using the treated efficacy set for TRANSCEND FL. Although liso-cel was associated with higher incidence of any-grade CRS (OR, 1.86 [1.01‒3.43]) and any-grade NEs (OR, 2.16 [0.72‒6.44]), it demonstrated a lower incidence of grade ≥ 3 CRS (OR, 0.45 [0.04‒5.13]) and grade 3-4 serious infections (OR, 0.35 [0.12‒1.03]) based on an ESS of 81.9 compared with mosunetuzumab. Furthermore, liso-cel was associated with reduced use of corticosteroids for CRS management (OR, 0.14 [0.03‒0.65]), while the use of tocilizumab was higher in patients treated with liso-cel (OR, 2.27 [0.86‒5.99]). Conclusions: In this MAIC, liso-cel was associated with improved efficacy compared with mosunetuzumab. Liso-cel had a lower incidence of grade ≥ 3 CRS, grade 3-4 serious infections, and steroid use for management of CRS; however, liso-cel exhibited higher incidence of any-grade CRS, any-grade NEs, and tocilizumab use for CRS management. Safety comparisons were confounded by preventative use of corticosteroids in all patients in GO29781 and definition differences, most notably for NEs. These findings highlight a potential positive benefit-risk profile of liso-cel over mosunetuzumab as a 3L+ tx option for R/R FL.