Long-Term Efficacy and Safety of Zanubrutinib in Patients with Relapsed/Refractory (R/R) Marginal Zone Lymphoma (MZL): Final Analysis of the Magnolia (BGB-3111-214) Trial

Introduction: Advanced MZL is generally incurable, with periods of remission and relapse. Zanubrutinib (BGB-3111), a potent and highly specific next-generation Bruton tyrosine kinase (BTK) inhibitor, was approved in the US and Canada for R/R MZL based on the MAGNOLIA primary analysis (BGB- 3111-214;NCT03846427);here, the final MAGNOLIA analysis is presented. Method(s): This was a phase 2, multicenter, single-arm study of adult patients (pts) with R/R MZL (>=1 prior CD20-directed therapy). Zanubrutinib (160 mg twice daily) was given until disease progression or unacceptable toxicity. The primary endpoint was overall response rate (ORR) by independent review committee (IRC) per Lugano classification. Secondary endpoints were investigator-assessed ORR, duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Efficacy was assessed by positron emission tomography (PET)-based Lugano criteria for IRC-confirmed fluorodeoxyglucose (FDG)-avid disease at baseline;non-avid disease was assessed by computed tomography (CT)-based criteria. Result(s): As of May 4, 2022, 68 pts were treated (median age=70 y [range 37-95];>=75 y=27.9%). MZL subtypes included extranodal (38.2%), nodal (38.2%), splenic (17.6%), and unknown (5.9%). The median number of prior therapies was 2 (range 1-6);32.4% of pts had disease refractory to last therapy, most (89.7%) had prior chemoimmunotherapy, and 7 (10.3%) had rituximab monotherapy as their only prior treatment. Sixty-one pts (89.7%) had FDG-avid disease. After a median follow-up of 28.0 mos (range 1.6-32.9) and a median treatment duration of 24.2 mos (range 0.9-32.9), 66 pts were efficacy- evaluable. IRC-assessed ORR (complete response [CR]+partial response [PR]) was 68.2% (CR=25.8%). By subtype, (Figure Presented)(Figure Presented)ORR/CR rates were 64.0%/40.0% (extranodal), 76.0%/20.0% (nodal), 66.7%/8.3% (splenic), and 50.0%/25.0% (unknown). Median DOR, PFS, and OS were not reached. Over 70.0% of pts were alive or progression-free after 2 years (Figure). Sensitivity analysis using only CT-based criteria (n=66) showed an ORR of 66.7% and CR of 24.2%. The most common treatment-emergent AEs were bruising (23.5%), diarrhea (22.1%), and constipation (17.6%). Neutropenia (8.8%) and COVID-19 pneumonia (5.9%) were the most common Grade >=3 AEs. Five pts (7.4%) died due to unrelated AEs: COVID-19 pneumonia=2, acute myeloid leukemia=1, myocardial infarction=1, septic encephalopathy=1. Hypertension occurred in 3 pts (4.4%), atrial fibrillation and atrial flutter in 1 pt (1.5%) each;none led to treatment withdrawal. One pt (1.5%) had a Grade 3 gastrointestinal hemorrhage while receiving rivaroxaban. None of the pts required dose reduction. Conclusion(s): In this final analysis with over 2 years of median follow-up, zanubrutinib continues to demonstrate durable disease control and was generally well tolerated, with no new safety signals observedCopyright © 2023 American Society for Transplantation and Cellular Therapy

Report of consensus panel 5 from the 11th international workshop on Waldenstrom's macroglobulinemia on COVID-19 prophylaxis and management.

Consensus Panel 5 (CP5) of the 11th International Workshop on Waldenstrom's Macroglobulinemia (IWWM-11; held in October 2022) was tasked with reviewing the current data on the coronavirus disease-2019 (COVID-19) prophylaxis and management in patients with Waldenstrom's Macroglobulinemia (WM). The key recommendations from IWWM-11 CP5 included the following: Booster vaccines for SARS-CoV-2 should be recommended to all patients with WM. Variant-specific booster vaccines, such as the bivalent vaccine for the ancestral Wuhan strain and the Omicron BA.4.5 strain, are important as novel mutants emerge and become dominant in the community. A temporary interruption in Bruton's Tyrosine Kinase-inhibitor (BTKi) or chemoimmunotherapy before vaccination might be considered. Patients under treatment with rituximab or BTK-inhibitors have lower antibody responses against SARS-CoV-2; thus, they should continue to follow preventive measures, including mask wearing and avoiding crowded places. Patients with WM are candidates for preexposure prophylaxis, if available and relevant to the dominant SARS-CoV-2 strains in a specific area. Oral antivirals should be offered to all symptomatic WM patients with mild to moderate COVID-19 regardless of vaccination, disease status or treatment, as soon as possible after the positive test and within 5 days of COVID-19-related symptom onset. Coadministration of ibrutinib or venetoclax with ritonavir should be avoided. In these patients, remdesivir offers an effective alternative. Patients with asymptomatic or oligosymptomatic COVID-19 should not interrupt treatment with a BTK inhibitor. Infection prophylaxis is essential in patients with WM and include general preventive measures, prophylaxis with antivirals and vaccination against common pathogens including SARS-CoV-2, influenza, and S. pneumoniae.

Report of Consensus Panel 5 from the 11th International Workshop on Waldenstrom's Macroglobulinemia on COVID-19 Prophylaxis and Management

Consensus Panel 5 (CP5) of the 11th International Workshop on Waldenstrom's Macroglobulinemia (IWWM-11;held in October 2022) was tasked with reviewing the current data on the coronavirus disease-2019 (COVID-19) prophylaxis and management in patients with Waldenstrom's Macroglobulinemia (WM). The key recommendations from IWWM-11 CP5 included the following: Booster vaccines for SARS-CoV-2 should be recommended to all patients with WM. Variant-specific booster vaccines, such as the bivalent vaccine for the ancestral Wuhan strain and the Omicron BA.4.5 strain, are important as novel mutants emerge and become dominant in the community. A temporary interruption in Bruton's Tyrosine Kinase-inhibitor (BTKi) or chemoimmunotherapy before vaccination might be considered. Patients under treatment with rituximab or BTK-inhibitors have lower antibody responses against SARS-CoV-2;thus, they should continue to follow preventive measures, including mask wearing and avoiding crowded places. Patients with WM are candidates for pre-exposure prophylaxis, if available and relevant to the dominant SARS-CoV-2 strains in a specific area. Oral antivirals should be offered to all symptomatic WM patients with mild to moderate COVID-19 regardless of vaccination, disease status or treatment, as soon as possible after the positive test and within 5 days of COVID-19-related symptom onset. Co-administration of ibrutinib or venetoclax with ritonavir should be avoided. In these patients, remdesivir offers an effective alternative. Patients with asymptomatic or oligosymptomatic COVID-19 should not interrupt treatment with a BTK inhibitor. Infection prophylaxis is essential in patients with WM and include general preventive measures, prophylaxis with antivirals and vaccination against common pathogens including SARS-CoV-2, influenza and S. pneumoniae.

EFFICACY OF A 3RD COVID VACCINE, INCLUDING DURING A BTKI PAUSE, IN INDIVIDUALS WITH WALDENSTRÖM MACROGLOBULINEMIA AND FOLLICULAR LYMPHOMA

Background: Patients (pts) with indolent lymphomas are at increased risk of severe COVID-19 infection. We have shown limited seroconversion and live viral neutralisation (VN), but preserved COVID-specific T cell responses after 2 doses of mRNA COVID-19 vaccination in such pts. (Beaton, B ASH 2021, 149348). A 3rd vaccine dose to complete primary vaccination has since been recommended. Aims: To assess humoral & cellular immune responses to a 3rd COVID-19 (mRNA) vaccination in pts with follicular lymphoma (FL) & Waldenström Macroglobulinemia (WM), including assessment of response after pausing BTKi therapy in WM pts. Methods: Patients with WM, FL & healthy controls (HC) were enrolled in a prospective observational study to measure immune responses 21-28 days after a 3rd mRNA COVID-19 vaccine. Immune response was measured by mean fluorescence intensity (MFI) of anti-SARS-CoV-2 spike antibodies (ASAb) obtained using a high-sensitivity live cell assay, live VN to a panel of SARS-CoV-2 variants of concern, and CD4+ & CD8+ antigen-specific T cell responses. The associated TRIBECA (TReatment Interruption of BTKi to Enhance COVID-19 Antibody response) study sought to determine if a superior immune response could be gained by pause of BTKi therapy prior to and up to 4 weeks after 3rd vaccine dose. Patients were closely monitored during the BTKi pause with weekly clinical, full blood count and IgM assessments. WM pts receiving a 3rd dose while continuing on BTKi served as a control. Statistical analysis of medians between cohorts were compared by the non-parametric Mann-Whitney (Graphpad Prism). Comparison of medians between paired grouped data was assessed by 2-way ANOVA. Results: To date, 56 of 125 pts had their ASAb measured following 3rd vaccine dose administered between October 2021 and January 2022: 28 WM pts (including 6/9 WM pts on the BTKi pause sub-study), 24 FL pts and 4 HC. Median age was 68 years with 21 females and 35 males. Median follow up from 2nd dose was 140 days (range: 79- 170 days). In antibody responders, median MFI fell from 163042 (IQR 82663-249934) 28 days post 2nd dose to 52117 (IQR 19942-60973) (p<0.0001) immediately before the 3rd dose. Median MFI in all FL & WM pts pre- 3rd dose vaccine was 17111 (IQR 0-52650), rising significantly post 3rd dose to a median of 86730 (IQR 0-221937). Only 4/20 pts without measurable ASAb prior to the 3rd dose (2 WM, 2 FL) developed measurable ASAb following the 3rd dose: 16/20 patients (8 WM, 8FL, all treated) had no ASAb response. The median MFI in pts who underwent a BTKi treatment pause rose from 9151 (IQR 1671-21232) pre-3rd dose to 87720 (IQR 2785-152195) post 3rd dose, significantly higher than the median MFI in WM pts who did not pause their BTKi , which rose from 16769 (IQR 218-22447) pre- to 20252 (IQR 168-114262) post 3rd dose, (p = 0.016). Of the 5/125 with COVID infection in the study to date, only one patient (without measurable ASAb) in this 3-dose cohort had COVID, requiring intensive care support. Summary/Conclusion: Most WM & FL pts who responded to a 2nd dose COVID vaccine showed a decline in ASAb titre over time which increased following a 3rd mRNA vaccine. Only 20% of pts without detectable ASAb pre- 3rd dose showed improvement post 3rd dose, highlighting the importance of other COVID protection strategies in these pts. Although initial numbers are small, there may be a higher increment in ASAb when BTKi therapy is paused around the time of vaccination. Comprehensive immune analysis, including VN and T-cell response on the entire FL & WM cohort will be presented at the EHA congress.

ZANUBRUTINIB IN OLDER PATIENTS (PTS) WITH RELAPSED/REFRACTORY (R/R) MARGINAL ZONE LYMPHOMA (MZL): SUBGROUP ANALYSIS OF THE MAGNOLIA STUDY

Background: MZL is the second most common lymphoma in older pts. Choosing an optimal treatment can be challenging because of patient-or disease-related risk factors and treatment-related toxicities (Curr Opin Oncol. 2019;31(5):386-393). Zanubrutinib is a potent, irreversible next-generation Bruton tyrosine kinase (BTK) inhibitor designed to maximize BTK occupancy and minimize off-target kinase inhibition, which may improve efficacy outcomes and minimize toxicities, such as cardiac arrythmias and bleeding events. Zanubrutinib received accelerated approval from the United States FDA for the treatment of pts with R/R MZL (Haematologica . 2022;107(1):35-43). Aims: We aim to present a subgroup analysis of efficacy and safety of zanubrutinib in pts aged ≥65 years with R/R MZL enrolled in MAGNOLIA (BGB-3111-214;NCT03846427). Methods: MAGNOLIA is a phase 2, multicenter, single-arm study of adults with R/R MZL who had received ≥1 line of therapy including ≥1 CD20-directed regimen. All were treated with zanubrutinib 160 mg twice daily until disease progression or unacceptable toxicity. Use of long-term antiplatelet and anticoagulation agents was permitted. The primary endpoint was overall response rate (ORR;complete response [CR] and partial response [PR]) determined by an independent review committee (IRC) in accordance with the Lugano classification. Secondary endpoints include ORR by investigator assessment (INV), duration of response (DOR), progression-free survival (PFS), and safety. All pts gave informed consent. Results: As of 18 January 2021, a total of 68 pts were enrolled (Table). Forty (61%) pts were ≥65 years old with a median age of 73 (range, 65-85);18 pts were ≥75 years old. Median number of prior therapies was 2 (range, 1-6) and 10 (25%) pts were refractory to last therapy. Most pts received prior rituximab + cyclophosphamide + vincristine + prednisone (48%) or bendamustine + rituximab (30%), while 5 (13%) pts received rituximab monotherapy. MZL subtypes included extranodal (n=17, 43%), nodal (n=14, 35%), and splenic (n=8, 20%). Median duration of treatment was 14.4 months (mo;range, 0.9-19.6). At a median follow-up of 15.8 mo (range, 2.8-21.8), ORR by IRC was 75% (CR 25%, PR 50%;Table). Responses were observed in all subtypes, with an ORR of 71%, 86%, and 75% in extranodal, nodal, and splenic subtypes, respectively (CR 41%, 21%, and 0%, respectively). Median DOR and PFS were not reached;15-month PFS was 87% and 12-month DOR was 93%. Most (63%) pts are continuing zanubrutinib. Treatment discontinuation due to disease progression was 28% by INV. Most common treatmentemergent adverse events (AEs) observed in ≥20% of pts include contusion (28%), diarrhea (25%), and constipation (20%). Grade ≥3 neutropenia occurred in 5% of pts. The most common infection was upper respiratory tract infection (10%). Two (5%) pts discontinued zanubrutinib due to unrelated fatal AEs (COVID-19 pneumonia and myocardial infarction in a patient with pre-existing coronary artery disease). Atrial fibrillation/flutter and hypertension occurred in 2 (5%) pts each and did not lead to treatment discontinuation. No pts required dose reductions, or experienced major or serious hemorrhage. Image: Summary/Conclusion: The safety profile of zanubrutinib observed in older pts was consistent with previously published results (Clin Cancer Res . 2021;27(23):6323-6332). Zanubrutinib was well tolerated and effective, as demonstrated by a high response rate and durable disease control in older pts with R/R MZL.

Efficacy of vaccine BNT162b2 (pfizer-biontech) in individuals with waldenstrom's macroglobulinemia and follicular lymphoma in Australia

Introduction Lymphoid malignancies are a risk factor for severe COVID-19. Vaccination with BNT162b2 protects the general population from severe disease, but recent studies have shown limited seroconversion after vaccination in patients with lymphoid malignancy. This reduced response is likely related to disease and treatment factors altering both humoral and cellular immunity. Assessing response in patients with the indolent lymphomas, Waldenström's Macroglobulinaemia (WM) and Follicular Lymphoma (FL), including cohorts on differing treatment regimens, may help elucidate some of these factors. Australia has had low prevalence of SARS-CoV-2 infection to date, affording a unique opportunity to assess efficacy to vaccination without the confounding impact of endemic infection. Methods Patients with WM and FL and controls were enrolled in a prospective study of immune response after two doses of BNT162b2 administered 21 days apart. The study had Human Research Ethics Committee approval and all patients gave informed consent prior to participation. Recruitment was targeted to obtain comparable proportions of controls to treatment cohorts. PBMC and sera were collected from participants immediately prior to the first dose (T1), at day 21 immediately prior to the second dose (T2), and day 49 (+/-7d) (T3). Immune response was measured by: flow cytometric detection of anti-SARS-CoV-2 spike antibodies (ASAb), performed using our recently validated flow cytometric live cell assay (Tea et.al. PLoS Medicine 2021) with increased sensitivity compared to currently available commercial ELISAs;live virus neutralisation to a panel of SARS-CoV-2 variants of concern;and CD4+and CD8+ antigenspecific T cell responses. Statistical analysis of medians between cohorts were compared by the Mann-Whitney non-parametric test using Graphpad Prism. Initial ASAb IgG data for T1 and T2 is presented here. Complete immune response data at all time points will be available for the ASH meeting. Results Eighty-five participants received their first dose of BNT162b2 from 18 May 2021 to 7 June 2021 with a second dose 21 days later: 72 lymphoma patients (WM and FL) and 13 age-matched healthy volunteers (controls). Of 37 with WM [19 (51.3%) female, median 71 years (IQR 63-74)] 9 were treatment naïve (WMN), 15 had received rituximab-chemotherapy (WMT), and 13 were currently treated with a Bruton Tyrosine Kinase inhibitor (BTKi): 5 ibrutinib, 8 zanubrutinib (WMB). Of 35 patients with FL [16 (45.7%) female, median 65 years (IQR 54-71)], 11 were treatment naïve (FLN), and 24 had received rituximab-chemotherapy (FLT). Of the 13 controls 8 (61.5%) were female, median age 72 years (IQR 57-74)]. No participants had detectable ASAb at T1, confirming no prior SARS-CoV-2 exposure. Figure 1 shows ASAb results at T2. The median mean fluorescence intensity (MFI) of healthy controls: 60802 (IQR 17565 -78443), is higher than all WM: 0 (IQR 0-15010) p<0.0001, and all FL patients: 1687 (IQR 0-25421) p=0.002, Fig 1A. The median MFI of controls was higher than WMN (p=0.036), but not higher than FLN (p=0.28). The median MFI of WMN: 20074 (IQR 5421-35695), is higher than WMB: 0 (IQR 0-4217) p=0.018, but not significantly higher than WMT: 0 (IQR 0-14356) p=0.13, Fig 1B. Median MFI of FLN: 31476 (IQR 19351-51317), is higher than FLT: 0 (IQR 0-32849) p=0.01, Fig 1B. Conclusion These early serological data show measurable ASAb in all healthy controls 21 days post first dose of BNT162b2 vaccination. Treatment naïve patients had a better response than treated patients, and this did not differ significantly to healthy controls in the FL cohort. In WM, patients on BTKi had a significantly reduced response compared to treatment-naïve patients. This same reduction was not observed in the chemotherapy-rituximab cohort, but the characteristics of early responders versus non-responders, including time since last therapy, is being analysed. FL patients treated with chemotherapy-rituximab had a significantly reduced response compared to the treatmentnaïve cohort. Time constraints before the submission deadline prevented reporting of all mature vaccination response data. Measurement of ASAb one month after second vaccination, live virus neutralisation to a panel of SARS-CoV-2 variants of concern, and CD4+ and CD8+ antigen-specific T cell responses at T1, T2 and T3, to fully characterise the immune response to BNT162b2, will be reported at the ASH meeting.

Global Waldenström's Macroglobulinemia Patient-Derived Data Registry, Whimsical, Highlights Real-World Treatment Outcomes and COVID-19 Data

Introduction: WhiMSICAL (Waldenström's Macroglobulinemia Study Involving CArt-wheeL) is the first global Waldenström's Macroglobulinemia (WM) registry capturing patient-derived data to complement scarce clinical trials data in this rare cancer (Tohidi-Esfahani et al, Am J Hematol 2021). The registry was interrogated to identify real-world first line treatment outcomes, quality of life (QoL) and coronavirus disease 2019 (COVID-19) data. Methods: The registry captures data through www.cart-wheel.org, an online rare cancer database, utilizing a tailored questionnaire developed by clinician and patient investigators. WM patients complete consent online, then enter symptom, pathology, treatment, QoL (EORTC QLQ-C30) and COVID-19 data, and can return to update their data on an ongoing basis. Recruitment is driven by social media messaging by the International Waldenström's Macroglobulinemia Foundation investigators. Time to next treatment (TTNT) was assessed from start of first therapy to start of second therapy. Patients without a documented second therapy were censored at the time of last edit to their account. COVID-19 questions included testing, disease severity, vaccination and impact on WM management. Results: As of July 2021, 558 patients from 20 countries have participated in the registry, predominantly from USA (50%), Australia (22%) and the UK (9%). Median age at diagnosis was 61 years (range 24-83) with male predominance (61%). 371 patients documented first-line therapies, with a total of 54 unique therapeutic combinations listed. The seven most common therapies were: bendamustine rituximab (BR, n=94), rituximab monotherapy (Rit., n=52), dexamethasone rituximab cyclophosphamide (DRC, n=33), ibrutinib (n=25), bortezomib dexamethasone rituximab (n=15), rituximab cyclophosphamide vincristine prednisolone (n=14) and chlorambucil (n=10). Comparison of TTNT was limited to the four most common first-line therapies: BR, Rit., DRC, with zanubrutinib (n=5) and ibrutinib plus rituximab (n=2) adding to the first line Bruton tyrosine Kinase inhibitor (BTKi) cohort (n=32). Median ages for the BR, BTKi, DRC and Rit. cohorts were 65, 66, 61 & 65 years, respectively. More patients in the BR cohort listed comorbidities (37%), with BTKi-treated patients reporting the least (19%). Pre-treatment disease burden (median IgM and hemoglobin) trended to being higher in the BR and DRC cohorts (figure 1B-D, IgM p=0.24, Hb p=0.27). At median follow up ranging from 31 to 39 months, BR had superior TTNT to DRC (median: not reached and 104 months, p=0.007, figure 1C) and Rit. (median 26 months, p < 0.0001, figure 1D), and trended to superiority compared to BTKi (median not reached, p=0.08, figure 1B). Median TTNT for the entire cohort (n=371) was 108 months (median follow up 55 months, figure 1A). Assessment of QoL was conducted in all patients (any line of treatment) and compared between patients currently on BTKi therapy (n=64) and patients not exposed to BTKi and treated within the last 12 months (n=84). The expanded BTKi cohort reported better QoL, with mean EORTC QLQ-C30 global scale of 82 ± 14.4 compared to the BTKi-naïve cohort mean 73.4 ± 20.9, p=0.005. This was despite more prior lines of treatment (median 2 [IQR 1-4] compared to 1 [IQR 1-1];p<0.0001). 324 (58%) patients responded to the COVID-19 questions. 144/324 (44%) had undergone testing for COVID-19, with 11 (8%) returning a positive result;none after vaccination. Median length of symptoms was seven days (range 2-30), with two hospitalized, one requiring intensive care. Both hospitalized patients were on second line ibrutinib. Of 211 responses regarding vaccination status, 15 (7%) were not vaccinated, eight due to availability, five due to personal choice and two due to clinician advice. Regarding impact of the pandemic on their WM management, 5% had treatment schedule disruption and 53% reported reduced face-to-face consultations. Conclusion: The WhiMSICAL registry provides a scientifically robust and ethically approved portal for the patients' voice. The data highligh the real-world efficacy of combination chemoimmunotherapy, particularly first-line BR, and suggest a better QoL with BTKi than other therapies. As this global data platform grows, the breadth of data allows for new insights into WM with patient reported outcomes advancing knowledge and facilitating treatment decisions for clinicians and patients. [Formula presented] Disclosures: D'Sa: Sanofi: Honoraria;BeiGene: Honoraria, Research Funding;Janssen Cilag: Honoraria, Research Funding. Kersten: Roche: Consultancy, Honoraria, Other: Travel support, Research Funding;Miltenyi Biotec: Consultancy, Honoraria, Other: Travel support;Novartis: Consultancy, Honoraria, Other: Travel support;BMS/Celgene: Consultancy, Honoraria;Takeda: Research Funding;Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding;Celgene: Research Funding. Thomas: Acerta Pharma: Research Funding;Ascentage Pharma: Research Funding;BeiGene: Membership on an entity's Board of Directors or advisory committees;BMS: Research Funding;Pharmacyclics: Membership on an entity's Board of Directors or advisory committees;X4 Pharma: Research Funding;Genentech: Research Funding. Palomba: Ceramedix: Honoraria;Rheos: Honoraria;Nektar: Honoraria;Priothera: Honoraria;Lygenesis: Honoraria;WindMIL: Honoraria;Wolters Kluwer: Patents & Royalties;Juno: Patents & Royalties;BeiGene: Consultancy;Kite: Consultancy;Magenta: Honoraria;Seres: Honoraria, Other: Stock, Patents & Royalties, Research Funding;PCYC: Consultancy;Notch: Honoraria, Other: Stock;Novartis: Consultancy;Pluto: Honoraria. Olszewski: Acrotech Pharma: Research Funding;Celldex Therapeutics: Research Funding;TG Therapeutics: Research Funding;PrecisionBio: Research Funding;Genentech, Inc.: Research Funding;Genmab: Research Funding. Trotman: PCYC: Research Funding;roche: Research Funding;BMS: Research Funding;TAKEDA: Research Funding;JANSSEN: Research Funding;beigene: Research Funding.

Phase 2 study of zanubrutinib in patients with relapsed/refractory marginal zone lymphoma (magnolia study)

Background: BCR signaling mediated through Bruton's tyrosine kinase (BTK) plays a critical role in the development and maintenance of marginal zone lymphoma (MZL). BTK inhibitors have established activity in relapsed/refractory (R/R) MZL with the phase 2 study of ibrutinib demonstrating an objective response rate (ORR) of 48% (Noy et al. Blood. 2017;129:2224-2232). Zanubrutinib is a potent and highly specific next-generation BTK inhibitor designed with greater selectivity for BTK vs TEC- and EGFRfamily kinases, which are thought to be related to off-target toxicities. Therapeutic activity of zanubrutinib was established in an early-phase study (BGB-3111-AU-003) of 20 patients (pts) with R/R MZL demonstrating an ORR of 80%, with a complete response (CR) rate of 15%, and partial response (PR) rate of 65% (Tedeschi et al. EHA 2020, abstract 2804). Aims: To present initial efficacy and safety results in pts with R/R MZL enrolled in MAGNOLIA (BGB-3111-214). Methods: MAGNOLIA is a phase 2, multicenter, single-arm study of adults with R/R MZL who had received ≥1 line of therapy including ≥1 CD20-directed regimen. All were treated with zanubrutinib 160 mg twice daily until disease progression or unacceptable toxicity. Use of long-term antiplatelet and anticoagulation agents was permitted. The primary end point was ORR determined by an independent review committee in accordance with the Lugano classification. Secondary end points include ORR by investigator assessment, duration of response (DOR), progression-free survival (PFS), and safety. Results: As of January 11, 2021, 68 pts were enrolled and treated. Median age was 70 years (range, 37-95), with 28% aged ≥75 years. Subtypes included extranodal (mucosa-associated lymphoid tissue;38%), nodal (38%), splenic (18%), and indeterminate (6%) MZL. Median number of prior therapies was 2 (range, 1-6) and 32% of pts had disease that was refractory to last therapy. Median duration of drug exposure was 59.1 weeks (range, 3.7-84.1). Sixty-six pts were evaluable for efficacy. At a median study follow-up of 15.5 months (range, 1.6-21.7), investigator-assessed ORR (CR + PR) was 74% (CR 24%, PR 50%, stable disease 17%). Responses were observed in all subtypes, with an ORR of 68%, 84%, 75%, and 50% in extranodal, nodal, splenic, and indeterminate subtypes, respectively. CR rate was 36% for extranodal MZL, 20% for nodal, 8% for splenic, and 25% for indeterminate subtype. Median DOR and PFS were not reached;15-month PFS was 68% and 12-month DOR was 81%. IRC review is ongoing. Twenty-eight (41%) pts discontinued treatment: 20 due to disease progression, 1 withdrew consent, 3 required prohibited medications, 4 due to adverse events (AEs;2 due to COVID-19 pneumonia, 1 due to pyrexia attributed to disease transformation, and 1 due to myocardial infarction [MI]). The most common (≥10%) treatment-emergent AEs reported were diarrhea (22%), bruising (21%), constipation (15%), pyrexia (13%), abdominal pain (12%), upper respiratory tract infection (12%), back pain (10%), and nausea (10%). Most AEs were grade 1 or 2. Neutropenia was the most common grade ≥3 AE (10%). Two pts died from COVID-19 pneumonia and 1 pt with pre-existing coronary artery disease died from MI. No fatal AEs were considered related to zanubrutinib. All-grade AEs of interest included neutropenia (13%), thrombocytopenia (13%), atrial fibrillation/flutter (3%), and hypertension (3%). No major/serious hemorrhage was reported. No AEs led to dose reductions. Summary/Conclusion: Zanubrutinib demonstrated high response rates and durable disease control with a favorable safety profile in pts with R/R MZL.