Untreated Mantle Cell Lymphoma Research Articles

Abstract CT145: The final results of a phase I study using velcade (bortezomib), cladribine, and rituximab (VCR) in treating elderly patient with mantle cell lymphoma

Abstract Background: Mantle cell lymphoma (MCL) is a moderately aggressive and incurable small to medium size B cell lymphoma. In this phase 1 study, we evaluated the safety and efficiency of Valcade, Cladribine, and Rituximab (VCR) combination treatment in MCL. Patients and Methods: This is a single arm, open label, investigator-initiated Phase 1 study. This study employed a standard 3+3 dose escalation scheme designed to determine the maximum tolerated dose (MTD) of Cladribine in VCR regimen. The treatment scheme and Cladribine dose escalation levels (1, 2, and 3) are as follows: the therapy consisted of 6 28-day cycles. At first cycle of the treatment, Rituximab 375 mg/m2 infusion started on day 5 of the first week and then given weekly for 3 weeks; in the next 5 cycles, Rituximab was given on day 5 of each cycle, and then every 2 months as the maintenance therapy. Cladribine 35 mg/m2 (3 mg/m2 for level 1, 4 mg/m2 for level 2, and 5 mg/m2 for level 3) infusion was given on days 1 to 5 for 6 cycles. If the patient was older than 70 years old, Cladribine was only given on days 1 to 3 of each cycle. Velcade 1.6 mg/m2 subcutaneous injection was given on days 12, 19 and 26 for cycles 1 to 3, then Day 5 and 19 during Cycles 4 to 6, then once per month as maintenance therapy until toxicity or progression of the disease. The primary endpoint of this study was to investigate the dose limiting toxicity (DLT), safety, and efficiency of this regimen in patients with MCL. The secondary endpoints included remission rate (RR), progression free survival (PFS) and overall survival (OS). This study is registered with clinicaltrials.gov (NCT01439750). Results: No subject experienced dose limited toxicity (DLT) at either level 1 or 2, one possible DLT (infectious colitis) was observed on a subject during 2nd cycle at level 3. Then no additional DLTs were seen in 3 subjects added to level 3. Overall, this study recruited 13 subjects, with a median age of 64 years old (range from 55 to 83), and a total of 11 male and 2 females. Ten subjects were never previously treated, while 3 either relapsed or failed previous treatments. The majority of subjects tolerated this regimen well. Two relapsed patients experienced disease progression after received two cycles of treatments and died in 5 and 7 months after initiating the treatment. Another patient died 15 months after starting treatment. The overall remission (OR) rate was 77% (10/13) and complete remission (CR) rate was 85% (10/13). In newly diagnosed subject cohort, the RR and OS rates were 90% (9/10), PFR was 80% (8/10), and CR rate was 100% (10/10), of which 3 patients have been followed for more than 4 years, 3 other patients for more than 3 years, and 3 others for over 2 years. However, in relapsed/refractory subject cohort, 1 subject achieved CR for 7 months but then relapsed, 2 subjects had no response. There were 2 blastoid subjects, one was newly diagnosed and achieved CR.No severe systemic toxicity was observed in this study. Bone marrow suppression caused prolonged anemia and thrombocytopenia were the most common toxicity (3/13 with ≤grade 2). Low grade peripheral neuropathies (≤grade 2) were observed in 15% (2/13). Mild fatigue was a frequent complaint. Conclusions: The VCR combination is a well-tolerated, low toxicity and effective regimen for for untreated MCL. Cladribine 5 mg/m2 is a tolerable dose with manageable toxicity. Citation Format: Jeffrey J. Pu, Kristin Berger, David Claxton, Joseph Drabick, Thomas Loughran, Elliot Epner. The final results of a phase I study using velcade (bortezomib), cladribine, and rituximab (VCR) in treating elderly patient with mantle cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT145.

Resolution on the experts' discussion of the TRIANGLE study results

On September 30, 2023, a discussion of the results of the European Community study on mantle cell lymphoma – TRIANGLE study was held in Moscow. The TRIANGLE phase III international randomized trial enrolled nearly 900 young subjects (up to 65 years of age) with histologically confirmed untreated mantle cell lymphoma in advanced stages II–IV. Study centers from 14 European countries participated in the study. According to the TRIANGLE study results, adding ibrutinib to autologous hematopoietic stem cell transplantation allows achieving a 3-year disease-free survival rate of 88%, which is significantly better than in the standard chemotherapy group.

Modified R-BAC plus BTK inhibitor regimen in newly diagnosed young patients with mantle cell lymphoma: a real-world retrospective study.

To explore the optimal treatment for young patients with untreated mantle cell lymphoma (MCL), we compared the efficacy and safety of R-CHOP/R-DHAP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone/rituximab, dexamethasone, cytarabine and cisplatin) and R-BAP (rituximab, bendamustine, cytarabine, and prednisone) plus BTK (Bruton's tyrosine kinase) inhibitors in newly diagnosed patients. Eighty-three young patients (≤ 65years old) with newly diagnosed MCL admitted to the First Affiliated Hospital of Zhengzhou University from January 1, 2014, to June 1, 2023, using R-CHOP/R-DHAP or R-BAP plus BTK inhibitor were assessed in this study. The median age at presentation was 60 (42-65) years in 83 patients, including 64 males and 19 females; 59 were treated with R-CHOP/R-DHAP regimen chemotherapy, and 24 were treated with R-BAP in combination with the BTK inhibitor regimen. The median follow-up was 17months (2-86months) in 83 patients, and the median PFS (progression-free survival) time was not reached. The CRR (complete response rate) of the R-BAP group was higher than that of the R-CHOP/R-DHAP group (87.5% vs. 54.2%, P = 0.005). The ORR (overall response rate) was not significantly different between the two groups (ORR: 91.7% vs. 84.7%, P = 0.497). The PFS (progression-free survival) of the R-BAP group was longer than that of the R-CHOP/R-DHAP group (P = 0.013), whereas OS was not significantly different between the two groups (P = 0.499). The most common adverse effect in both groups was hematotoxicity, with a higher incidence of grade 3-4 lymphopenia and grade 3-4 thrombocytopenia in the R-BAP group than in the R-CHOP/R-DHAP group (P = 0.015 and P = 0.039). Male sex (HR = 4.257, P = 0.013), LDH (lactate dehydrogenase) ≥ 245 U/L (HR = 3.221, P = 0.012), pleomorphic-blastoid (HR = 2.802, P = 0.043) and R-CHOP/R-DHAP regimen (HR = 7.704, P = 0.047) were independent risk factors for PFS. Ki67 ≥ 30% (HR = 8.539, P = 0.005) was an independent risk factor for OS. First-line treatment with R-BAP in combination with BTK inhibitor improved CRR and prolonged PFS in young patients with mantle cell lymphoma and adverse events were tolerable.

Ibrutinib as first-line therapy for mantle cell lymphoma: a multicenter, real-world UK study

AbstractDuring the COVID-19 pandemic, ibrutinib with or without rituximab was approved in England for initial treatment of mantle cell lymphoma (MCL) instead of immunochemotherapy. Because limited data are available in this setting, we conducted an observational cohort study evaluating safety and efficacy. Adults receiving ibrutinib with or without rituximab for untreated MCL were evaluated for treatment toxicity, response, and survival, including outcomes in high-risk MCL (TP53 mutation/deletion/p53 overexpression, blastoid/pleomorphic, or Ki67 ≥ 30%). A total of 149 patients from 43 participating centers were enrolled: 74.1% male, median age 75 years, 75.2% Eastern Cooperative Oncology Group status of 0 to 1, 36.2% high-risk, and 8.9% autologous transplant candidates. All patients received ≥1 cycle ibrutinib (median, 8 cycles), 39.0% with rituximab. Grade ≥3 toxicity occurred in 20.3%, and 33.8% required dose reductions/delays. At 15.6-month median follow-up, 41.6% discontinued ibrutinib, 8.1% due to toxicity. Of 104 response-assessed patients, overall (ORR) and complete response (CR) rates were 71.2% and 20.2%, respectively. ORR was 77.3% (low risk) vs 59.0% (high risk) (P = .05) and 78.7% (ibrutinib-rituximab) vs 64.9% (ibrutinib; P = .13). Median progression-free survival (PFS) was 26.0 months (all patients); 13.7 months (high risk) vs not reached (NR) (low risk; hazard ratio [HR], 2.19; P = .004). Median overall survival was NR (all); 14.8 months (high risk) vs NR (low risk; HR, 2.36; P = .005). Median post-ibrutinib survival was 1.4 months, longer in 41.9% patients receiving subsequent treatment (median, 8.6 vs 0.6 months; HR, 0.36; P = .002). Ibrutinib with or without rituximab was effective and well tolerated as first-line treatment of MCL, including older and transplant-ineligible patients. PFS and OS were significantly inferior in one-third of patients with high-risk disease and those unsuitable for post-ibrutinib treatment, highlighting the need for novel approaches in these groups.

A Phase II Study of Zanubrutinib-Based Induction and Maintenance Therapy in Young and Fit Patients with Untreated Mantle Cell Lymphoma (BRIDGE): An Updated Analysis with Long-Term Follow up

Introduction Studies showed that remission after induction therapy is associated with better prognosis in mantle cell lymphoma (MCL) patients, and minimal residual disease (MRD) is also considered as an independent and sensitive factor in MCL patients. As R-CHOP/R-DHAOx is the most common used induction regimen in China, we investigate the benefit of zanubrutinib-based induction (zanubrutinib plus R-CHOP) in untreated young MCL patients. We previously reported a promising result of an ORR of 100% with MRD negative rate of 100% after induction treatment in 2022 PPLC. Here, we reported a long-time (median follow-up: 25.9 months) efficacy and safety in the study. Methods In this prospective, single-center, single-arm, phase II study (NCT04736914), patients aged 18-65 years with previously untreated, Ann Arbor stage II-IV, histologically confirmed MCL will be enrolled to alternately receive R-CHOP + zanubrutinib and R-DHAOx induction for 6 cycles (every 21 days per cycle). Zanubrutinib will be administered in cycle 1, 3, 5 (R-CHOP), 160 mg BID, d1-21, and not in combination with R-DHAOx. Patients who achieve remission (≥PR) will be allowed to proceed to ASCT or maintenance depending on the investigator's evaluation and discretion. In patients who do not achieve a remission at the end of induction (treatment failure), no specific treatment is defined; rather, the further salvage treatment is upon the discretion of investigators. Patients will receive zanubrutinib maintenance for two years in case of remission at ASCT assessment or end of induction assessment. Zanubrutinib is administrated orally at 160 mg BID, continuously for 2 years or until progressive disease, unacceptable toxicity, or death, whichever occurs first. The primary endpoint was bone marrow MRD negative rate after induction therapy (at the completion of cycle 6 or at premature discontinuation). Results A total of 7 patients were enrolled, the median age was 56.3, and bone marrow (BM), peripheral blood (PB) MRD showed positive at baseline. After 6 cycles of R-CHOP + zanubrutinib and R-DHAOx induction treatment, BM and PB MRD negative rate was 100% (7/7). One patient proceeded to ASCT. At the data cut-off date of 30 Jun 2023, one patient has completed the study at week 53 with zanubrutinib maintenance treatment due to the progressive disease, while the other 6 patients remain in the zanubrutinib maintenance treatment and are still under follow-up (Figure). With a median follow-up of 25.9 months, all patients showed good tolerance, with no dose modification and discontinuation during zanubrutinib-based induction therapy, either no BTKi interested AE (includes diarrhea, hypertension, major hemorrhage, and atrial fibrillation/flutter) was observed (Table). Conclusions This prospective, phase II study with a relatively longer follow-up duration estimated the treatment regimen in untreated young MCL patients. At the time of data cut-off, zanubrutinib-based induction therapy was well tolerated in all patients and showed a promising results in response and MRD. With a median treatment duration of 16.6 months, most patients (6/7) did not relapse. The study is ongoing and further results will be continuously released.

A Multicenter Phase 2 Trial of Zanubrutinib, Obinutuzumab, and Venetoclax (BOVen) in Patients with Treatment-Naïve, TP53-Mutant Mantle Cell Lymphoma

Background: TP53-mutant mantle cell lymphoma (MCL) is associated with poor survival outcomes with chemoimmunotherapy (Eskelund, Blood 2017) with median progression-free survival (PFS) of 0.9 years and median overall survival (OS) of 1.8 years. There is no standard frontline treatment for this high-risk subset. The combination of Bruton's tyrosine kinase (BTK) inhibition and BCL2 inhibition were synergistic and active in relapsed, refractory MCL, including in patients with TP53 mutation (Tam, NEJM 2018). Obinutuzumab, ibrutinib, and venetoclax were well tolerated and efficacious in relapsed and untreated MCL patients (Le Gouill, Blood 2021). We hypothesized that treatment with zanubrutinib (Zanu), Obinutuzumab (Obin), and venetoclax (Ven) (BOVen) would be well-tolerated and efficacious in untreated TP53-mutant MCL. Methods:In this multicenter, investigator-initiated phase 2 trial (NCT03824483), eligible patients had previously untreated MCL with TP53 mutation (of any variant allele frequency) and ECOG PS ≤2, ANC >1, PLT >75, HGB ≥9 (unless if due to MCL). BOVen is administered in 28-day cycles: Zanu 160 mg PO BID starting D1; Obin 1000 mg IV D1 or split D1-2, 8, 15 of C1, D1 of C2-8; Ven ramp up initiated C3D1 (target 400 mg QD). Treatment duration is 2 years at minimum and the primary endpoint is 2-year PFS. Response was assessed using Lugano criteria (Cheson, JCO 2014). PFS and OS were estimated using the Kaplan-Meier method. Peripheral blood minimal residual disease (PB-MRD) assessment was performed using the Adaptive clonoSEQ ® assay. After 24 cycles, Zanu and Ven can be discontinued if MRD undetectable (<10 -6) complete remission (CR) is achieved. With subsequent PB-MRD monitoring, patients can be retreated if clinical progression or MRD detectability (>10 -6). Adverse events (AE) were assessed per CTCAE v5. Results: All 25 planned patients have been enrolled (May 15, 2023 data cut). The median age on study was 65 years (range 29 - 82); 76% were male (19/25); various histologic subtypes were included (15 conventional MCL, 5 non-nodal leukemic, and 5 blastoid variant); 100% stage IV (25/25); by MIPI: 68% high risk (17/25), 28% intermediate (7/25), and 4% low risk MIPI score (1/25); 67% Ki67 ≥30% (14/21); 33% Ki67≥50% (7/21); 100% TP53 mutation, and 48% 17p deletion (12/25). Treatment was overall well-tolerated. The most common treatment-related AEs (≥20%) were predominantly low-grade and manageable, including diarrhea (52%), neutropenia (28%), infusion-related reaction (24%), bruising (20%), COVID-19 infection (20%), nausea (20%), thrombocytopenia (20%), and rash (20%). The grade 3 or higher treatment-related AEs were neutropenia (12%), infusion-related reaction (8%), COVID-19 (8%), diarrhea (4%), transaminitis (4%), thrombocytopenia without bleeding (4%), and rash (4%). Detailed toxicity data will be presented in future. Median follow-up was 16.1 months. There were 5 progressions and 4 deaths on study (2 COVID-related, 1 post-operative aspiration pneumonia, 1 unknown cause), see Figure 1. All deaths occurred in patients who were in ongoing response at time of death. The best overall response rate was 95% (24/25) with 88% (22/25) achieving a CR. At C3 post Zanu-Obin, 68% (n=17/25) achieved PET-CR and post cycle 3, 5 patients converted to a PET-CR (Figure 1). The 1-year PFS and overall survival (OS) were 84% (95% CI: 71%, 100%) and 96% (95% CI: 89%, 100), respectively. The 16-month PFS and OS were 75% (95% CI: 60%, 95%) and 87% (95% CI: 75%, 100%), respectively. The 16-month PFS and OS for patients less than 65 years of age (n=9) were both 100%. Seven patients completed 24 treatment cycles. Of these, 71% (5/7 pts) were in CR and MRD undetectable (treatment discontinued) and 29% (2/7 pts) were in CR and MRD detectable (continued treatment). Outcomes post C24 will be presented in future. At 10 -6 MRD sensitivity level, 7 (28%) of 23 patients had undetectable MRD at C3 and 16 (100%) of 16 patients at C13. Conclusions:BOVen is a well-tolerated, outpatient regimen associated with high response rates and high rates of undetectable MRD in untreated TP53-mutant MCL. The early PFS and OS estimates with BOVen compare favorably with historical outcomes of chemoimmunotherapy in this high-risk subset of MCL. Based on this data, BOVen emerges as a promising treatment option for TP53-mutant MCL and, therefore, the study was expanded to include an additional 25 (total 50) TP53-mutant MCL patients.

Use of an Integrated Functional Quantitation of Modulation of Transcriptional Pathways (IFQ) Assay in Untreated Mantle Cell Lymphoma Patients

Background: Mantle cell lymphoma (MCL) is an extremely heterogenous cancer, with substantial variation in clinical presentation and genetic makeup among individual patients. Chronic exposure to cytokines or inflammatory mediators is hypothesized to mediate pathogenesis and influence presentation in MCL, thus representing a key area of interest for prognostication and identification of therapeutic targets. However, measuring a large panel of individual cytokines, binding proteins, and soluble receptors does not give an integrated measure of how much a given pathway is activated within individual cells from a patient. Therefore, we have developed a cell-based reporter assay that can measure in an integrated way the activating potential of patient plasma samples on four central transcription factor-driven pathways: the interferon pathway (STAT1), the acute phase response (STAT3), lymphocyte-targeted cytokines (STAT5), and the inflammatory pathway (NF-κB). In this study, we applied this Integrated Functional Quantitation of Modulation of Transcriptional Pathways (IFQ) assay to plasma from patients with untreated MCL. We hypothesized that the IFQ assay of these transcriptional pathways would be associated with response to treatment and provide prognostic information on the outcome of these patients. Methods: Reporter cell lines were generated in which the activity of each of these four transcription factors, STAT1, STAT3, STAT5, and NF-κB, regulated expression of a luciferase reporter gene (Figure 1). We identified stored plasma samples collected from patients with untreated MCL who had consented to an IRB-approved research protocol. Cells from the 4 cell lines were plated in quadruplicate in 96-well plates at a concentration of 5000 cells per well and treated with patient plasma prior to incubation for 1 hour. Stimulator media was then added to each well and the plates were incubated for 6 hours after which luciferase activity was quantitated by luminometry. Values were normalized to stimulator-only control and media-only control. Results: Plasma from 14 patients with untreated MCL was analyzed. The luciferase assay system was successful for all patients, with results shown in Figure 2. Five of 6 patients with downregulation of STAT1 compared to stimulator-only control went into remission without a reported relapse following frontline therapy, whereas both samples with upregulation of STAT1 later had relapsed disease within 1 year of treatment completion. Conversely, 4 of 6 samples found to have upregulation of STAT3 went into sustained remission following therapy, while the single sample showing downregulation went into sustained remission after frontline therapy. Six samples did not reveal a conclusive change in regulation of the STAT3 gene when measured against the control. When evaluating NF-κB expression levels, 12 samples showed downregulation of the gene compared to the stimulator-only control, although no pattern in treatment response was discerned. STAT5 expression showed fewer differences compared to the stimulator-only control group, as 12 of 14 plasma samples conveyed no upregulation or downregulation of the gene. Discussion: Evaluation of transcription factor expression in the plasma of patients with MCL using the luciferase reporter system is feasible. In our patient population, NF-κB was downregulated in the majority of patients, whereas STAT1 and STAT3 showed differential patterns of expression. STAT1 and STAT3 merit further investigation as possible biomarkers of treatment response, perhaps due to their role in initiating and sustaining inflammation. In the future, we hope to augment these data to strengthen this correlation and to implement this assay to aid in prognostication and treatment selection.

A Prospective Multicenter Phase II Study of Orelabrutinib-Lenalidomide-Rituximab (OLR) in Patients with Untreated Mantle Cell Lymphoma (MCL) in China (POLARIS Study): Preliminary Analysis on Efficacy, Safety, Mutation Spectrum and Impact of Mutation Profiling on Treatment Responses

Background: Recently, the first-line treatment of MCL has been continuously evolving with the introduction of targeted agents and chemo-free regimens. It is well-known that bruton's tyrosine kinase (BTK) inhibitors were effective with MCL patients (pts). Orelabrutinib (O), a novel highly selective BTK inhibitor, has shown high response rates and good tolerability in R/R MCL (Song et al. Blood. 2020). Besides, O combined with rituximab (R) could preserve NK cell mediated ADCC induced by R and enhance the apoptosis of tumor (Yu et al. Mol Ther Oncolytics. 2021). Thus, we hypothesized that OLR would exhibit synergistic antitumor activity in MCL and improve the depth and durability of responses. Here, we reported the preliminary data on efficacy, safety, and mutation spectrum of OLR regimen in untreated MCL from the POLARIS study (NCT05076097). Methods: Pts ≥18 years with untreated MCL were enrolled in this prospective, multicenter, single-arm phase 2 study. All pts received OLR-induction therapy on a 28-day cycle for 6 cycles (O, 150 mg/d; L, 15 mg on days 1-21, then 20 mg of cycles 2-6 if tolerated or 10 mg if not tolerated; R, 375 mg/m 2 on days 1, 8, 15, 22, then day 1 of cycles 3, 5), followed by OLR-maintenance therapy for up to 18 cycles. Primary endpoint was complete response rate (CRR) after 6 cycles of induction treatment. Secondary endpoints included overall response rate (ORR), time to response (TTR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Exploratory endpoint was to explore the prognostic value of detecting peripheral blood (PB) ctDNA by NGS. Results: As of July 10, 2023,a total of 28 pts (male, 89.3%; median age, 60.0 y [range, 53.0-64.5]) were enrolled. Baseline characteristics included 96.4% Eastern Cooperative Oncology Group performance status of 0-1, 82.1% stage III-IV disease, 57.1% Ki67 index (≥30%), 75.0% low-risk MIPI scores, 42.9% bone marrow involvement, and 60.7% maximum lesion diameter of ≥5 cm. Twenty-one pts (75.0%) who have completed 6 cycles of induction therapy were evaluable for response, 16 (76.2%) had a complete response (CR) and 5 (23.8%) had a partial response (PR), with an ORR of 100% ( Figure 1). In addition, 18 of 21 pts were available for minimal residual disease (MRD) analysis, and PB-MRD and bone marrow MRD (BM-MRD) of the 18 pts were negative. The results of CRR were reported across different subgroups stratified by Ki67 index (<30% vs. ≥30%, 66.7% and 83.3%), MIPI scores (low vs. intermediate, 81.3% and 60.0%), maximum lesion diameter (<5 cm vs. ≥5 cm, 87.5% and 69.2%), and bone marrow involvement (yes vs. no, 83.3% and 73.3%). With a median follow-up of 11.0 months, the median TTR was 3.0 months (range, 2.8-3.4). Median DOR and median PFS were not reached, with the estimated 12-month DOR rate and PFS rate of 90.9% and 92.3%, respectively. Mutationalspectrum (475 panels) was determined in 23 pts. The spectrum of gene mutations is depicted by PB samples and tissue samples at baseline in Figure 2. The most common mutated genes in tissues samples were: ATM (48%), KMT2D (43%), CCND1 (17%), SMARCA4(17%), ARID2 (13%), BCOR (13%), BIRC3 (13%), NFKBIE (13%), NOTCH1 (13%), ACTB (9%), CDK12 (9%), FANCC(9%),FAT1(9%),KLF2(9%),MEF2B(9%),MET(9%),SETD2(9%), TP53 (13%),TERT(9%). The most common mutated genes in PB samples were: ATM (48%), KMT2D (39%), DNMT3A (17%), BIRC3 (13%), CCND1 (13%), TP53 (13%), BCOR (9%), CARD11 (9%), CBLB (9%), CRYBG1 (9%), FAT1(9%), NOTCH1 (9%), GRIN2A (9%), KDM5A (9%), KLHL6(9%), KRAS (9%), MAP3K14 (9%). For all gene mutations, 75.4% (43/57) detected in tissue were also found in PB samples. Further, more additional mutated genes can be detected in plasma. Meanwhile, 4 of 23 pts had a PR, 1 of 4 had multiple gene mutations in PB samples, including BTK and TP53. This suggests that ctDNA detection may potentially predict that these gene mutations are associated with depth of remission. Twenty-six (92.9%) pts experienced adverse events (AEs). The most common AEs (any grades, ≥3 grades) were neutropenia (64.3%, 39.3%), leukopenia (60.7%, 14.3%), thrombocytopenia (35.7%, 7.1%), lymphopenia (35.7%, 3.6%), and COVID-19 infection (28.6%, 7.1%). At the time of data cut-off, 26 pts remained on study. No deaths were observed. Conclusions: The preliminary findings show that the OLR exerted synergistic antitumor activity, with manageable toxicity in untreated MCL. Detection of PB ctDNA by NGS method may help to predict prognosis.

Six Years Follow up of Ibrutinib Plus Rituximab (IR) Followed By Short Course R-Hyper CVAD/MTX in Patients (age ≤ 65 years) with Previously Untreated Mantle Cell Lymphoma - Phase-II Window-1 Clinical Trial

Background - We reported the efficacy and safety of using a combination of ibrutinib plus rituximab (IR) induction followed by short course (4 cycles) of R-HCVAD/MTX-ara-C as consolidation in previously untreated young (age ≤ 65 years)patients (pts) with mantle cell lymphoma (MCL), Wang M et al Lancet Oncology 2022. Here we report the long term follow up of this study. Methods - We enrolled 131 previously untreated pts in this single institution, single arm, phase II clinical trial - NCT02427620. Pts received IR induction (part-A), until they achieved complete remission (CR) for up to a maximum of 12 cycles, followed by a maximum of 4 cycles of R-HCVAD/R-MTX-ara-C (part-B) as consolidation. The primary objective was to assess overall response rate (ORR), [defined as either a partial response (PR) or a complete response (CR)] after part A. Adverse events were coded as per CTCAE version 4. High risk pts received ibrutinib for 1 year and rituximab once every 2 months for 24 months after completion of part B. Results - Among the 131 pts, the median age was 56 yrs (range - 35-65). High Ki-67 (≥30%) in 58/117 (49.5%) pts, 10 pts (8%) had high risk simplified MIPI score, 15 pts (11%) had aggressive MCL (blastoid/pleomorphic) and 114 pts (87%) had initial bone marrow involvement. Fifty percent of the patients had Ki-67 (≥30%). ORR in part-A was 98% (87% CR). After completion of part A and part B, ORR was 90% (89% CR). After a median follow up of 71 months, 43 patients progressed/died. The median progression free survival (PFS) and overall survival (OS) were not reached. Overall, 30 pts (23%) relapsed after treatment, including 5 who transformed to aggressive MCL. PFS among pts with high and low Ki-67% was 42 months vs not reached (P=0.01) while no difference was observed in OS. PFS was significantly shorter in pts with aggressive histology (p=0.001) but not the OS. PFS was similar in pts who received maintenance vs no maintenance therapy. Overall, 8 pts died (4 with progression, 2 due to disease transformation, one on study due to multiple complications including splenic hematoma, cardio-pulmonary arrest and progression and the last one expired outside and came off study due to encephalitis). 50 pts came off study for various reasons [30 disease progression (including 5 transformation), 10 pt choice, 8 intolerance, 1 second cancer and 1 lost to follow up]. Long term, grade 3-4 toxicities on part A were 6% myelosuppression and 10% each with fatigue, myalgia and rashes and 2% mucositis. Maintenance therapy did not show high toxicities. Conclusions -Long term follow up of chemo-free induction with IR induced durable and deep responses in young MCL pts in the frontline setting. Short course R-HCVAD chemotherapy minimized toxicities and consolidated responses. IR maintenance improved survival outcomes. This combined modality treatment approach may significantly improve young MCL pts outcomes across all risk groups.

Obinutuzumab Versus Rituximab in Transplant Eligible Untreated MCL Patients, a Matching Comparison between the Lyma and Lyma-101 Trials

Aim: Obinutuzumab (O) and Rituximab (R) have never been compared in a prospective randomized trial in mantle cell lymphoma (MCL). The LYMA-101 trial (NCT02896582) investigated the Obinutuzumab-DHAP (O-DHAP) regimen followed by autologous stem cell transplant (O-BEAM, ASCT) plus O maintenance (OM) in transplant eligible patients <66y with untreated MCL (Le Gouill et al, Lancet Hem 2020). The LYMA trial (NCT00921414) used the same regimen with Rituximab instead of Obinutuzumab (Le Gouill et al, NEJM 2017). Herein, we report the long-term outcome of patients enrolled in the LYMA-101 trial and used a propensity score matching (PSM) approach to allow a comparison with patients treated in the LYMA trial (i.e. O versus R group matched comparison). Method: LYMA (n=299 pts, of whom 120 received R Maintenance, RM) is a phase III prospective trial with a median follow-up of 7.5 years (7.4-7.7) from inclusion (Sarkozy et al, ASCO 2023) that randomized, after ASCT, 240 pts between observation and RM. LYMA-101 (n=86) is a prospective single arm phase 2 trial with a median FU of 5.1y (5-5.25) at the time of the present analysis. We first compared minimal residual disease (MRD) at end of induction (EOI), assessed in both trial with quantitative PCR of clonal immunoglobulin gene and used PSM based on clinical characteristics at inclusion (Sex, Ann Arbor stage, MIPI score, B symptoms, blastoid variant, bulky disease) to balance patients' discrepancies between LYMA-101 and LYMA. To compare PFS and OS from inclusion of patients treated with R versus O based regimen, half of the non-randomized LYMA patients (29 out of 58) were randomly reattributed to the RM arm to create an intention to treat RM (RM-ITT) arm including 149 pts (29 non-randomized and 120 randomized) subsequently matched with the 86 LYMA-101 pts. Balance between populations was checked using standardized mean differences (SMD). Results: Eighty-five LYMA-101 pts received the first course of O-DHAP (1 withdrew consent before treatment), 81 (95.3%) completed the 4 cycles and 73 (85.9%) underwent ASCT followed by OM in 69 (81.2%). The estimated 5y PFS and OS since inclusion were 83.4% (95%CI: 73.5-89.8%) and 86.9% (95%CI: 77.6-92.5%) respectively. At EOI, ORR were similar in both studies (89.6% versus 91.8% in LYMA versus LYMA-101 respectively), but within responders, pts treated in LYMA-101 (O-DHAP) had a more frequent MRD negativity than pts treated in LYMA (R-DHAP) both in bone marrow (BM, 82.1% versus 65.3% MRD negativity in O vs R group, Chi2 p=0.011) and blood (95.5% versus 79.2% of MRD negativity in O vs R group, Chi2 p=0.002). These results were confirmed using the propensity score matched populations, with a more frequent MRD negativity in the O versus R group in BM (82.1% vs 63.4%, Chi-2, p=0.01) and blood (95.5% vs 72.9%, Chi-2, p<0.001). To compare PFS and OS since induction, a PSM was performed using the 149 patients treated in the R-group with an RM-ITT and the 85 patients in the O group, resulting in 2 sets of 82 patients with comparable characteristics at inclusion. From treatment initiation, patients treated with O presented a prolonged PFS (p=0.029, figure 1A) and OS (p=0.039, figure 1B) compared to those treated with R, with an estimated 5-year PFS of 82.8% versus 66.6% (HR 1.99, IC95 1.05-3.76) and OS of 86.4% versus 71.4% (HR 2.08, IC95 1.01-4.16) with O and R based regimen respectively. Finally, 37/120 (30.8%) patients in LYMA and 23/69 (33.3%) in LYMA-101 prematurely stopped R and OM respectively (with a similar mean maintenance duration of 29 and 29.4m with R and OM respectively). Reason for maintenance discontinuation were adverse events in 15 cases in R group (12.5% of the population) versus 14 cases in O group (20% of the population), progression or death in 10 (8.3%) versus 3 (4.3%) cases in the R versus O group respectively. Causes of death were comparable in O and R groups, the most common being lymphoma (42% in O and 53% in R group). Infectious deaths in the O group (N=3) were all COVID related (3/12 deaths, 25%), whereas in the R group (LYMA being conducted before the pandemic), 8 deaths were related to infection (8/97 deaths, 8%, including 1 infectious death out of 22 deaths during RM, 5%). Conclusion: O-DHAP followed by OM post ASCT provide prolonged PFS and OS in young patients with MCL. O-based therapy in MCL induce deeper response with increased MRD negativity and seems to outperform R-based therapy in term of PFS and OS, without any significant excess of toxicity.

A Window Study of Acalabrutinib & Rituximab, Followed By Chemotherapy & Autograft (ASCT) in Fit Patients with Treatment Naïve Mantle Cell Lymphoma (MCL): First Report of the Investigator-Initiated Australasian Leukaemia & Lymphoma Group NHL33 ‘Wamm’ Trial

Introduction Bruton's tyrosine kinase inhibitors (BTKi) have improved 1 st line therapy efficacy in elderly (Wang NEJM 2022) and young, fit, MCL-the latter with intermittent dosing during RCHOP in an alternating RCHOP/cytarabine-based regimen (Dreyling Blood 2022). However direct combination of BTKi & intensive chemo is toxic in DLBCL studies. (Kuruvilla Haematol Oncol 2017). The highly selective BTKi, acalabrutinib (A), has proven efficacy and tolerability in relapsed MCL (Wang Lancet 2018). RDHAOx chemotherapy (rituximab, dexamethasone, cytarabine, oxaliplatin) prior to ASCT provides a complete response (CR) rate of 77% and favourable toxicity compared to many induction regimens (Le Gouill Blood 2017). Furthermore, Obinutuzumab-DHAP yields undetectable minimum residual disease (MRD) in 85% of young MCL patients. (Le Gouill Haematol Oncol 2019). Here we report the primary endpoint from the Australasian Leukaemia & Lymphoma Group phase 2 ‘WAMM’ trial exploring a ‘sandwich’ model of an acalabrutinib-rituximab (AR) ‘window’ before RDHAOx +/- ASCT, followed by fixed-duration AR-maintenance to improve therapy response and minimise additional toxicity. Methods NHL33'WAMM' (ACTRN12619000990123) is a multicentre single-arm phase 2 trial. Key eligibility included: age 18-70 years, untreated histologically-proven stage II-IV MCL, ECOG<2; no contraindications to ASCT or BTKi. Pts received 2 cycles of AR (AR window); ‘A’ dose; 100mg BD PO, ‘R’ dose; 375mg/m 2 IV (day 1) every 4 weeks, followed by RDHAOx x4 cycles. Those with an objective response (CR or partial response-PR) underwent BEAM ASCT (carmustine, etoposide, cytarabine, melphalan) then AR maintenance (A; 1yr continuous & R; 3-monthly x 8 cycles). Those who did not undergo BEAM ASCT were able to remain on study and proceed to maintenance AR in the event of ongoing response. Co-primary endpoints (EP) were safety; defined by lack of prohibitive toxicity causing treatment cessation AND PET-determined complete response (CR) rate after AR+RDHAOx. Secondary EP include overall response rates (ORR), toxicity, overall survival (OS) & progression-free survival (PFS), MRD negativity rates and quality of life. Only Grade 3+ toxicity related to acalabrutinib was collected during the ASCT period. Baseline whole exome sequencing was performed to identify mutations, MRD analysis was done by LymphoTrack® Dx and MRD Assay platform (Invivoscribe, Inc) using Illumina® MiSeq. This study was the first Australian blood cancer trial to use telehealth and a ‘hub-and-spoke’ transplant model. Results 44 pts were enrolled from Sept 2020 to Apr 2022 (43 evaluable for the primary endpoint). Baseline characteristics were typical of a young MCL cohort: median age 59 years (Interquartile range 54-64), 77% were male, ECOG was 0-1 in 98%, 84% had stage IV, lactate dehydrogenase was elevated in 35%, Ki-67 >30% in 66% and blastoid/pleomorphic histology 9%. TP53 by NGS will be reported at presentation. CR rate post AR+RDHAOx induction was 88%; (95%CI 72-95) with ORR 95% and no prohibitive toxicity. AR window ORR was 93% (CR 57%). MRD negativity was achieved in 18% (7/38) post AR window, and 94% (34/36) post RDHAOx. 43 patients remained evaluable for response after R-DHAOX and pre-maintenance with 35 (80%) who underwent ASCT and 38 (86%) who commenced AR maintenance; 7 remain on maintenance. Response in specific subgroups will be reported at the meeting. At data lock, 35 pts (81%) experienced ≥1 G3+ adverse events during induction or maintenance phases, most common were neutropenia (58% of pts), febrile neutropenia (27%), thrombocytopenia (25%), diarrhea (14%). No G5 treatment-related events have occurred to date. There have been 22 SAEs, most common were COVID (3), febrile neutropenia (2) and fever (2). 5 deaths have been reported: 4 in pts with progressive disease and 1 COVID pneumonitis during AR maintenance. After a median follow up of 22 months (range 17-28m), the 2-year OS was 89%. Analysis of survival, quality of life and biomarkers will be reported with more mature follow up. Conclusion AR delivered in a sandwich approach is active and safe. An AR window yields a high ORR and compared to historical studies, improves post-chemo induction CR rates and MRD negativity. A telehealth model allowed rapid recruitment in a rare cancer.

Minimal Residual Disease (MRD) Testing By Next Generation Sequencing (NGS) after Two Cycles (CY) of Non-Intensive Chemoimmunotherapy Is Predictive of Remission Duration and Need for Maintenance Therapy (MT) in Previously Untreated Mantle Cell Lymphoma (MCL): A Wisconsin Oncology Network Study

Introduction: Despite the variable course of MCL, limited prospective markers exist to identify more indolent disease. MCL is often diagnosed in older patients (pts) less able to tolerate intensive approaches. Bendamustine/rituximab (BR) is a standard non-intensive regimen for MCL, and use of MT remains controversial. Emerging data in MCL suggest a correlation between achieving MRD negativity (MRD-) and progression-free survival (PFS). The GALLIUM study (Marcus R, et al, N Engl J Med 2017) previously showed improved PFS with a bendamustine/obinutuzumab (BO) induction compared with BR in follicular lymphoma, and we postulated this benefit may be observed in MCL. Using MRD testing, we predicted that MT may be omitted in pts achieving MRD- status after induction BO chemoimmunotherapy for MCL. Methods: Adult pts ≥18 years (yrs) with previously untreated MCL who were ineligible for more intensive therapies (including transplant) were enrolled. Pts received 4-6 CY of BO induction intravenously (IV) every 28 days (D) with B 90 mg/m2 IV D1 & 2 every 28D for 6 CY concurrent with O IV (cycle 1 = 100 mg D1, 900 mg D2, and 1000 mg D8 & 15; then 1000 mg D1, CY 2-6). Peripheral blood (PB) MRD was obtained using NGS (ClonoSEQ®) after cycle 2 BO as an exploratory endpoint. Consolidation O (CO) 1000 mg IV weekly for 4 doses was initiated ≤12 weeks after the final dose of BO. Restaging and MRD testing of PB and bone marrow aspirate (BMA) was done ≤30 days after CO completion. For pts with complete response (CR) radiographically and MRD- in PB/BMA, maintenance O (MO) was omitted. For pts without CR or persistent MRD positivity (MRD+) in the PB or BMA, MO was given with 1000 mg IV D1 of a 56-day cycle for 8 CY. Pts were followed for ≥2 years from therapy completion. The primary endpoint is PFS from D1 of BO induction. Secondary endpoints are MRD status, concordance rate of PB/BMA in predicting MRD status, response rates and overall survival (OS). Results: Twenty-one pts (of planned 32) enrolled beginning 2/2018, with follow-up through 6/1/2023. The study closed prematurely due to slow enrollment. Median age is 70 yrs with 3 pts >80 yrs; majority were men (76%). Median MIPI score is 6.11 and median ECOG performance status 0. Twenty pts (95%) have stage IV disease. Twenty pts completed 4 (n=1) or 6 CY BO. Ten pts received MO; 10 did not receive MO per protocol due to radiographic CR and MRD- PB/BMA post-CO. Six pts did not complete MO for reasons of progressive disease (n=4), infection (n=1) and new carcinoma (n=1). After cycle 2 BO, PB analysis was MRD+ in 7 pts and MRD- in 13. Concordance rates between post-CO MRD testing in PB and BMA was 70% (14/20). Of non-concordant values, all had PB MRD- but BMA MRD+. Best responses in 20 assessable pts are: CR 75% (15/20), partial response 20% (4/20), and stable disease 5% (1/20). Most common grade 3/4 toxicities were: neutropenia (10/21), leukopenia (6/21), infections (5/21) and infusion reactions (2/21). One pt had grade 5 cardiac arrest with sepsis during BO. Most common grade 3 infections were abdominal/colitis (n=3) and pneumonia (n=2). Most common grade 1/2 toxicities were nausea (14/21), diarrhea (10/21), constipation (8/21), dysgeusia (6/21), fatigue (8/21) and dry skin/rash (12/21). After a median duration of follow-up of 43.9 months (mos) (95% confidence interval [CI] 28.3-60.1), PFS at 2-yrs and 3-yrs is 66.0% (95% CI 41.6-82.2) and 58.7% (95% CI 33.2-77.3), respectively; and median PFS is 46.5 mos (95% CI 16.4-∞). MRD- status after the exploratory endpoint post-C2 BO was predictive of 2-year PFS (Figure 1a), 83.3% (95% CI 48.2-95.6) for MRD- vs. 42.9% (95% CI 9.78-73.4) for MRD+, with hazard ratio [HR] 0.34 (95% CI 0.09-1.39), p value 0.133. Evaluation of PFS by MRD status post-CO showed similar outcomes regardless of receiving MO (Figure 1b): 2-year PFS is 77.8% (95% CI 36.5-93.9) in MRD- pts post-CO vs 60.0% (95% CI 25.3-82.7) in MRD+ pts; HR 0.45 (95% CI 0.10-1.91, p value 0.278. Median OS is 46.5 mos (95% CI 35.1-∞). Conclusion: Omission of MO in pts achieving MRD- status after induction/CO did not result in worsening PFS. Observed PFS and toxicities with BO induction and CO appears comparable with other data sets utilizing a BR-based induction +/- MT in older, less fit MCL pts. Correlation between PFS and PB MRD testing after C2 induction therapy represents a potential new prognostic marker of MCL behavior, and may be an important early disease indicator in development of risk-adapted therapies.

Harnessing Btki Therapy By CDK4/6i Control of T Effector Memory Cells and T Cell Surveillance in Mantle Cell Lymphoma

Drug resistance remains a formidable challenge in mantle cell lymphoma (MCL). Cell cycle dysregulation driven by aberrant Cyclin D1 and CDK4 expression is a hallmark for MCL, providing a rationale for targeting the cell cycle in MCL therapy. We have demonstrated in preclinical studies that inhibition of CDK4/6 not only induces early G1 cell cycle arrest, but also reprograms MCL cells for cytotoxic killing. On this basis, we investigated if inhibition of cyclin D1/CDK4 with palbociclib (CDK4/6 inhibitor) could reprogram recurrent MCL to deepen and prolong the ibrutinib (BTK inhibitor) response in a phase I clinical trial, and the resistance mechanism by longitudinal genomic analysis of sequential samples from individual patients in the context of the clinical response. Palbociclib was administered to MCL patients on days 1-21 of a 28-day cycle; ibrutinib was given continuously. For longitudinal genomic analysis, sequential tissue and blood specimens from 27 evaluable MCL patients before and during therapy, and on progression were collected. Single cell RNA-seq (scRNA-seq) of PBMC or the monocytic fractions from bone marrow and lymph node (53 samples) was performed using a unique in house MCL cell-specific library. PBMC from normal donors (n=4) and untreated MCL patients (n=4) served as controls. The data were then subject to multiplex analysis with whole transcriptome sequencing and whole exome sequencing of MCL cells isolated from the same specimens, as well as flowcytometry in conjunction with IHC. Total numbers of MCL and immune cells in each specimen were deduced by integrating complete blood counts (CBC) with differential with scRNA-seq or flowcytometry. CDK4/6 Inhibition appears to deepen and prolong the BTKi response, with a CR rate of 42% and 5 patients (2 CR and 3 PR) remained on therapy for ~ 9 years. Longitudinal scRNA-seq (210,000 cells) revealed that MCL cells comprise 4 major transcriptomically distinct clusters. Cluster 1 (C1) resembles quiescent normal B cells; C2 mimics hyper-activated B cells that are enriched for signatures of BCR and cytokine signaling; C3 represents non-proliferating, long-lived MCL cells; and C4 is highly proliferative. RNA velocity analysis further indicates that having progressed to late G1 after evading CDK4/6 inhibition, MCL cells in C2 are in transit to C4. By contrast, C3 is a terminal node of MCL cells arrested in late G1 with elevated BCL2 expression Primary resistance and progression on therapy were associated with a marked expansion of either long-live non-proliferating C3 MCL cells, or C2 MCL cells that fuel the proliferating C4 MCL cells. Resistance was also associated with a profound reduction in MHC I and MHC II expression on MCL cells in some patients. Moreover, concurrent with disease progression, CD8+ T and CD+T cells were rapidly depleted by different mechanisms ( Figure 1). CD8+ T cells were proliferating and eliminated by exhaustion, as evidenced by the marked expression of LAG3TIGIT and TIM3, and a failure to maintain CD8+ T effector memory cells. By contrast, CD4+ T cells were not proliferating and appeared die from glucose starvation. Collectively, these data suggest that T cell maintenance and surveillance is pivotal in sustaining a durable clinical response to combined inhibition of CDK4/6 and BTK. Guided by these discoveries, we have now restored BTKi sensitivity ex vivo in MCL cells from resistant patientsby targeting patient-specific expansion of C2 or C3 in vivo. In one resistant patient, this led to the maintenance of CD4+ and CD8+ T effector memory cells and a CR in response to venetoclax plus BTKi for nearly 3 years and continuing. In summary, by integrated longitudinal scRNA-seq analysis of a hypothesis-driven therapy, we have provided the first evidence that 1) MCL cells comprise 4 major transcriptomically distinct clusters; 2) resistance to CDK4/6i is associated with expansion of C2 that fuels the proliferating C4 MCL cells, or the long-lived C3 MCL cells with elevated BCL2 expression; 3) CDK4/6i harnesses BTKi response by promoting the maintenance of effector memory T cells; 4) combined inhibition of BCL2 and BTK overrides resistance to CDK4/6i and BTKi, leading to a durable clinical response; and 5) T cell surveillance is pivotal for a durable response to CDK4/6, BTK or BCL2 inhibition; implicating genome-guided combination therapy to overcome therapy resistance in MCL.

Rituximab Combined with Chemotherapy and Acalabrutinib Prior to Autologous Stem Cell Transplantation in Mantle Cell Lymphoma: The Rectangle Trial

INTRODUCTION In the European MCL Network Triangle study (Dreyling, ASH 2022) the addition of ibrutinib to frontline rituximab-containing chemotherapy and subsequent maintenance therapy improved failure-free survival in young, fit patients with mantle cell lymphoma (MCL). Ibrutinib was administered with R-CHOP, but not with R-DHAP, during the induction phase. Continuous, uninterrupted Bruton Tyrosine Kinase (BTK) inhibition could maximize the benefit of front-line therapy given that responses develop over time. Acalabrutinib has less off-target BTK inhibition than ibrutinib. We hypothesize that combining continuous acalabrutinib with R-CHOP may result in a tolerable, outpatient, highly active regimen producing favorable outcomes. METHODS NCT04566887 is a phase II, single-arm, open-label study conducted across 5 academic centres in Canada. Patients ≥ 18 years of age with previously untreated MCL, ECOG performance status 0-2, adequate organ function and considered fit for autologous stem cell transplantation (ASCT) were included. Patients received 6 cycles of R-CHOP at standard doses plus acalabrutinib 100 mg twice per day orally. Responding patients proceeded with ASCT and maintenance rituximab and acalabrutinib for a total of 2 years. The primary endpoint was the complete response (CR) rate after 6 cycles of induction with centrally reviewed PET/CT using the Lugano Criteria (Cheson, 2014). The total sample size was n=54 and the study completed accrual in May 2023. We present the results of the first 43 patients who have completed response assessment according to local investigators after 6 cycles of induction. RESULTS The median age was 62 years (range 38 - 69), 26 (60%) were male, 42 (98%) had performance status 0-1, 33 (78%) Ann Arbor stage IV, 35 (81%) bone marrow involvement, 6 (14%) high risk MIPI, 7 (16%) blastoid/pleomorphic morphology, 11 (26%) Ki67 ≥30%. All patients completed 6 cycles of induction and proceeded to ASCT. The overall response rate was 100%, and 39 (91%) patients achieved a CR. All patients started maintenance acalabrutinib + rituximab, although none have yet completed two years of protocol maintenance therapy. With a median follow up of 11.8 months (range 3.4 - 25.3) by the reverse Kaplan-Meier method, the 12-month PFS was 94% (95% CI 78.1 - 98.5), shown in Figure 1, and OS 95.5% (95% CI 71.9 - 99.3). Three subjects have developed PD so far, all with adverse clinical and biological factors: Baseline high-risk MIPI and Ki67 70%; biopsy at relapse TP53 positive by immunohistochemistry (IHC)Baseline intermediate risk MIPI and Ki67 60%; biopsy at relapse with pleomorphic morphology, TP53 positive by IHC, Ki67 100%Baseline high risk MIPI, Ki67 ≥30%, and blastoid morphology. Table 1 lists common grade 3-4 adverse events (AE) during induction and maintenance. There were no grade 5 AE. Neutropenia was the most common AE during induction and maintenance. Most infections were respiratory. Cardiovascular toxicity was uncommon. CONCLUSIONS Acalabrutinib + R-CHOP is associated with a 91% CR rate with low rates of grade 3-4 AE expected for this combination. All patients have proceeded to ASCT and subsequent maintenance therapy. Maintenance therapy in this setting is associated with additional toxicity, particularly cytopenias and infections.

The Final Results of a Phase I Study Using Bortezomib (Velcade), Cladribine, and Rituximab (VCR) in Treating Mantle Cell Lymphoma

Background: Mantle cell lymphoma (MCL) is a moderately aggressive and incurable small to medium sized B cell lymphoma. No standardized treatment exists for this disease. Cladribine is a hypomethylating agent that indirectly down-regulate DNA methylation to suppress tumorigenesis. Combination of Cladribine and Rituximab showed a synergetic effect in treating B cell lymphomas. Bortezomib (Velcade) is an FDA approved proteasome inhibitor to treat relapsed/refractory MCL. In this study, we evaluated the safety and efficacy of Valcade, Cladribine, and Rituximab (VCR) combination treatment in newly diagnosed and relapsed/refractory MCL. Patients and Methods: This is a single arm open label phase I trial. This study employed a standard 3+3 dose escalation scheme designed to determine the maximum tolerated dose (MTD) of Cladribine in VCR regimen. Briefly, the treatment scheme was consisted of 6 28-day cycles. At first cycle of the treatment, Rituximab 375 mg/m 2 infusion started on day 5 of the first week and then given weekly for 3 weeks; in the next 5 cycles Rituximab was given on day 5 of each cycle, and then every 2 months as the maintenance therapy. Cladribine 3 to 5 mg/m 2 (3 mg/m 2 for level 1, 4 mg/m 2 for level 2, and 5 mg/m 2 for level 3) infusion was given on days 1 to 5 for 6 cycles. For patient older than 70 years old, Cladribine was only given on days 1 to 3 of each cycle. Velcade 1.6 mg/m 2 subcutaneous injection was given on days 12, 19 and 26 for cycles 1 to 3, Days 5 and 19 for Cycles 4 to 6, then once per month as maintenance therapy. The primary endpoint of this study was the dose limiting toxicity (DLT), safety, and efficacy of this regimen in patients with MCL. The secondary endpoints included remission rate (RR), progression free survival (PFS) and overall survival (OS) (Figure 1). The analysis was done by intent to treat. Differentially methylated region (DMR) analysis and cytokine assay were performed to explore biomarkers differentiating good-responders from poor-responders. Results: This study recruited 13 patients, with a median age of 64 years old (range from 55 to 83) and including 11 males and 2 females. Ten patients were never previously treated, other 3 either relapsed or failed from previous treatments. Most patients tolerated this regimen well. No patient experienced DLT at either level 1 or 2, one possible DLT (infectious colitis) was observed during 2nd cycle at level 3. Two relapsed patients experienced disease progression after received two cycles of treatment and died in 5 and 7 months. Another patient died in 15 months after receiving treatment. The overall remission (OR) rate was 85% (11/13) and complete remission (CR) rate was 77% (10/13). In newly diagnosed patient cohort, CR rate was 100% (10/10), OS rates were 90% (9/10), and PFS was 80% (8/10), of which 3 patients have been followed for more than 4 years, 3 other patients for more than 3 years, and 3 others for over 2 years (Fig.1). In relapsed/refractory patient cohort, 1 achieved CR for 7 months but then relapsed, 2 had no response. There were 2 blastoid patients, 1 of these 2 patients was newly diagnosed and achieved CR. Bone marrow suppression caused prolonged anemia and thrombocytopenia were the most common toxicity (3/13 with ≤grade 2). Low grade peripheral neuropathies (≤grade 2) were observed in 15% (2/13). Mild fatigue was a frequent complaint. Cytokine assay showed decreased CXCL12 level in the good responders. Though global methylation pattern showed no difference, DMRs were identified in the good responders and the poor responders. DMRs-related genes involved in CXCL2 pathways were further extracted and enriched biological process analysis revealed the pathway profile difference between good responders and poor responders. Good responders exhibited alternation of apoptotic and Wnt signaling pathways (Fig.2). Conclusions: The VCR combination is a well-tolerated, low toxicity and effective regimen for MCL, especially for untreated MCL. Cladribine 5 mg/m 2 is a tolerable dose with manageable toxicity. Individual patient methylation profile may affect response to VCR therapy.

Evaluation of clinical parameters and biomarkers in older, untreated mantle cell lymphoma patients receiving bendamustine-rituximab.

Mantle cell lymphoma (MCL) is clinically and biologically heterogeneous. While various prognostic features have been proposed, none currently impact therapy selection, particularly in older patients, for whom treatment is primarily dictated by age and comorbidities. Herein, we undertook a comprehensive comparison of clinicopathological features in a cohort of patients 60 years and older, uniformly treated with bendamustine and rituximab, with a median survival of >8 years. The strongest prognostic indicators in this cohort were a high-risk call by a simplified MCL international prognostic index (s-MIPI) (HR: 3.32, 95% CI: 1.65-6.68 compared to low risk), a high-risk call by MCL35 (HR: 10.34, 95% CI: 2.37-45.20 compared to low risk) and blastoid cytology (HR: 4.21, 95% CR: 1.92-9.22 compared to classic). Patients called high risk by both the s-MIPI and MCL35 had the most dismal prognosis (HR: 11.58, 95% CI: 4.10-32.72), while those with high risk by either had a moderate but clinically relevant prognosis (HR: 2.95, 95% CI: 1.49-5.82). A robust assay to assess proliferation, such as MCL35, along with stringent guidelines for cytological evaluation of MCL, in combination with MIPI, may be a strong path to risk-stratify older MCL patients in future clinical trials.

FIVE‐YEAR UPDATE OF THE FIRST‐LINE IMCL‐2015 GELTAMO STUDY. PROLONGED MOLECULAR AND CLINICAL RESPONSES WERE OBSERVED AFTER MRD‐DRIVEN IBRUTINIB DISCONTINUATION

Introduction: A frontline tailored treatment for indolent clinical forms of mantle cell lymphoma (MCL) with ibrutinib in combination with rituximab was evaluated. A high rate of complete remissions (CR) with undetectable minimal residual disease (MRD) was reported, with predictable toxicity (Giné, JCO 2022). We herein present an updated analysis focusing in the data of treatment discontinuation. Methods: This was an open-label, phase II trial conducted in 14 Spanish GELTAMO sites (NCT02682641). Centralized histology, PET-CT review, MRD studies (qPCR and NGS in peripheral blood) and biological studies were conducted. Previously untreated MCL patients with indolent clinical forms were eligible according to the following criteria: no symptoms attributable to MCL, ECOG 0–1, stable disease without therapy need for at least 3 months, non-blastoid variants, Ki-67 <30% and largest tumor diameter ≤3 cm. Both leukemic non-nodal and nodal forms were acceptable. Patients received ibrutinib 560 mg daily and a total of 8 doses of rituximab 375 mg/m2 (4 weekly doses during the first 28-day cycle, followed by day 1 of cycles 3, 5, 7 and 9). Ibrutinib could be discontinued after 2 years of treatment in case of sustained undetectable MRD. Results: Fifty patients (Male 66%; median age 65 years) were enrolled in the study (June 2016 to December 2019, data cut-off 18 October 2022, median follow-up 54 months and next cut-off is planned in March 2023). The overall response (OR) and CR rates at 12 months of treatment were 84% and 80%, respectively (including 4 early discontinuations). Undetectable MRD was reached in 40 (87%) of 46 evaluable cases (sensitivity 10−5). After 24 months, 42 of 44 patients were in response, with OR and CR rates of 86% and 84%, respectively. Undetectable MRD was observed in 35 (80%) of 44 cases. Thirty-two patients discontinued ibrutinib as per protocol (64% of initial series). Twelve patients continued on ibrutinib. Median time on ibrutinib treatment was 29 months (1.7–51+ months). The median duration of undetectable MRD, achieved in 41 cases, was 60 months (95% CI: 29–92), and has not been reached in the 32 cases that stopped ibrutinib as per protocol. Six patients progressed from the disease between 12 and 72 months of follow-up and three of them eventually died of disease progression. Overall, PFS and OS at 48 months were 86% (95% CI: 75–96) and 88% (95% CI: 79–98), respectively. At current follow-up, 6 patients remain on treatment, and up to 13 patients discontinued ibrutinib because of adverse events, including 7 associated to ibrutinib with a hemorrhagic cardiac tamponade being the most severe. Five secondary neoplasms in 4 patients have been reported. Whole-genome sequencing of paired tumor/normal samples from 34 patients was obtained and will be presented. The research was funded by: The funding for the IMCL-2015 was obtained through unrestricted Janssen Clinical Investigator-Initiated Study (IIS) Research Support Keywords: aggressive B-cell non-Hodgkin lymphoma, molecular targeted therapies Conflicts of interests pertinent to the abstract E. Giné Consultant or advisory role: Gilead, Milteny Honoraria: Janssen, Genmab, Gilead Research funding: Janssen Educational grants: Janssen A. Medina-Herrera Research funding: Janssen Educational grants: Invivoscribe F. de la Cruz Honoraria: Roche, Takeda, Eusa Pharma, Abbvie, Janssen, Beigene, Kiowa Kirin, Astrazeneca and Gilead J. López Jiménez Honoraria: Roche, Abbvie, Janssen and Gilead Research funding: Roche Educational grants: Gilead, Janssen, Abbvie A. Martín García- Sancho Consultant or advisory role: Roche, Celgene/BMS, Morphosys, Kyowa Kirin, Clinigen, Eusa Pharma, Novartis, Gilead, Servier, Incyte Honoraria: Roche, Celgene, Janssen, Servier, Gilead Research funding: Janssen Educational grants: Roche, Servier, Celgene, Janssen, KernPharma M. J. Terol Research funding: Gilead Educational grants: Janssen, Gilead/Kite, Roche, Abbvie A. de la Fuente Honoraria: Abbvie, Astellas Pharma, BMS, incite, JazzPharma, Novartis, Roche and Pfizer Research funding: Janssen, Novartis Educational grants: Abbvie, Astellas Pharma, BMS, Incyte, Janssen, JazzPharma, Mundipharma, Roche, Pfizer A. Marín Niebla Consultant or advisory role: Janssen, Gilead, Kiowa Kirin, Takeda, Beigene Honoraria: Gilead/Kite, Janssen, Genmab Educational grants: Takeda, Janssen, Kiowa Kirin T. J. González López Honoraria: Novartis, Amgen, Sobi, Grifols and Mome Research funding: Novartis, Amgen X. Setoain Honoraria: Roche, Gilead, General Electric Educational grants: General Electric, Takeda R. García Sanz Honoraria: Janssen, Beigene Research funding: Janssen A. López Guillermo Consultant or advisory role: Roche, Gilead/Kite, Celgene, Novartis, Janssen, Abbie, Spectrum Honoraria: Roche, Celgene, Gilead/Kite Research funding: Roche, Celgene, Gilead

Adding venetoclax to lenalidomide and rituximab is safe and effective in patients with untreated mantle cell lymphoma

AbstractMantle cell lymphoma (MCL) is a rare, incurable hematological malignancy with a heterogeneous presentation and clinical course. A wide variety of chemotherapy-based regimens are currently used in patients who are untreated. Over the last several years, several targeted or small-molecule therapies have shown efficacy in the relapsed/refractory setting and have since been explored in the frontline setting. Lenalidomide plus rituximab was explored in a phase 2 study of 38 patients with MCL who were untreated and ineligible to receive transplantation, in which the combination produced durable remissions. We looked to build upon this regimen by adding venetoclax to the combination. We conducted a multicenter, open-label, nonrandomized, single-arm study to evaluate this combination. We enrolled 28 unselected patients with untreated disease irrespective of age, fitness, or risk factors. Lenalidomide was dosed at 20 mg daily from days 1 to 21 of each 28-day cycle. The dose of venetoclax was determined using the time-to-event continual reassessment method. Rituximab was dosed at 375 mg/m2 weekly, starting on cycle 1, day 1 until cycle 2, day 1. No dose-limiting toxicities were noted. All patients were treated with venetoclax at the maximum tolerated dose of 400 mg daily. The most common adverse events were neutropenia and thrombocytopenia. The overall and complete response rates were 96% and 86%, respectively. In total, 86% of patients achieved minimal residual disease undetectability via next-generation sequencing. The median overall and progression-free survivals were not reached. The combination of lenalidomide, rituximab, and venetoclax is a safe and effective regimen in patients with untreated MCL. This trial was registered at www.clinicaltrials.gov as #NCT03523975.

Bortezomib advanced mechanisms of action in multiple myeloma, solid and liquid tumors along with its novel therapeutic applications.

Bortezomib (BTZ) is a first-in-class reversible and selective proteasome inhibitor. It inhibits the ubiquitin proteasome pathway that leads to the degradation of many intracellular proteins. Initially, BTZ was FDA approved for the treatment of refractory or relapsed multiple myeloma (MM) in 2003. Later, its usage was approved for patients with previously untreated MM. In 2006, BTZ was approved for the treatment of relapsed or refractory Mantle Cell Lymphoma (MCL) and, in 2014, for previously untreated MCL. BTZ has been extensively studied either alone or in combination with other drugs for the treatment of different liquid tumors especially in MM. However, limited data evaluated the efficacy and safety of using BTZ in patients with solid tumors. In this review, we will discuss the advanced and novel mechanisms of action of BTZ documented in MM, solid tumors and liquid tumors. Moreover, we will shed the light on the newly discovered pharmacological effects of BTZ in other prevalent diseases.

Bendamustine, Obinutuzumab and Venetoclax Results in High Complete Response Rates in Untreated Mantle Cell Lymphoma

Bendamustine and Rituximab (BR) is a common induction therapy for untreated mantle cell lymphoma (MCL) with high efficacy in both transplant eligible (SWOG 1106 trial) and ineligible (StIL/BRIGHT trials) populations. However, patients will invariably relapse after BR and there is interest in incorporating novel agents into the frontline setting (SHINE trial). The efficacy of venetoclax has been described in the relapsed setting as both a single agent and in combination (AIM trial) in relapsed MCL. We developed a phase 2 study of bendamustine, obinutuzumab, and venetoclax (BOV) for untreated patients with MCL to determine the efficacy and toxicity of this combination (NCT03872180). Patients ≥ 18 years old with untreated MCL received up to six 28-day cycles of the regimen, consisting of bendamustine (90mg/m2 on days 1 and 2) and obinutuzumab (1000mg, C1: D 1,8,15 and C2-6: D1). Venetoclax was ramped up from 20mg to 200mg during cycle 1, and subsequently dosed at 400mg on days 1-10 of cycles 2-6. Post-induction therapy was determined by the treating physician and was not dictated by the study. The primary endpoint was CR rate by the end of induction, per Lugano criteria. Growth factor support was mandatory along with viral and PJP prophylaxis as well as CMV and tumor lysis syndrome monitoring. We targeted a sample size of 23 evaluable patients, with a target CR rate of 85%, based on the previously reported CR rate of 60% with B-R. Patients completed an interim PET/CT after 4 cycles and then again at the conclusion of cycle 6. 23 patients have enrolled, 16 patients have completed treatment per protocol and 1 patient has completed therapy, with upcoming end of treatment response assessment. 6 patients discontinued treatment prior to completion of therapy due to: disease progression (n=2), recurrent grade 3 thrombocytopenia (n=1), recurrent grade 3 neutropenia (n=2), and CMV viremia without CMV disease (n=1). Median age was 62 years old (range 41 - 80) with 9 patients 65 years and older. 6 (26%) patients were female. Of the 16 patients who completed protocol defined therapy; the responses at end of induction were: CR (n=14), PR (n=1), and PD (n=1). The final patient on protocol therapy is on cycle 6 with significant clinical improvement and a PR on interim PET. All patients who came off protocol therapy early due to toxicity (n=4) achieved a CR on their interim restaging. MRD status and survival status will be shared at the meeting. Grade 3+ hematologic toxicities include: Neutropenia (n=6), anemia (n=2), and thrombocytopenia (n=4). Two patients experienced grade 3 TLS and 1 patient experienced grade 4 TLS with hyperkalemia - all recovered and continued on therapy. Grade 3+ infectious complications included appendicitis (n=1) and CMV viremia (n=1). There were 2 patients who experienced grade 3 infusions reactions, one of whom declined further Obinutuzumab. There were no deaths attributable to therapy. One patient was unable to mobilize adequate stem cells for a planned autologous stem cell transplant. Bendamustine, obinutuzumab and venetoclax in combination is characterized with favorable response rates in the context of previous trials (StIL, BRIGHT, SHINE), with 19 of 22 patients achieving a response (86%) and 18 of 22 patients (81%) achieving a complete response (1 additional patient is pending final response assessment per protocol). The complete response rates in the StIL and BRIGHT trials were 40% and 31% respectively, and the BR+ibrutinib arm of SHINE had a CR of 66%. Three of 22 patients had to discontinue protocol therapy for high grade cytopenias. This regimen is highly active and future studies may consider an abbreviated course of bendamustine to limit myelosuppression while maintaining a high CR rate.