Session: 642. Chronic Lymphocytic Leukemia: Clinical and Epidemiological I
Hematology Disease Topics & Pathways:
Lymphoid Leukemias, Adults, Biological, Clinical Trials, CLL, Clinical Research, Diseases, Therapies, Lymphoid Malignancies, Monoclonal Antibody Therapy, Study Population
Methods: This is a phase II, multicenter, open label clinical trial (NCT04016805). Eligible patients were receiving ongoing ibrutinib, in any line of therapy, for a minimum duration of 6 months and had detectable residual CLL in the peripheral blood via MRD assay (flow cytometry with a cutoff of 10^-4 for uMRD). Umbralisib (administered daily at 800mg) and ublituximab (administered intravenously at 900 mg on Days 1/2 [split 150/750 mg], 8, and 15 of Cycle 1, Day 1 of Cycles 2–6, and on Day 1 every 3 cycles after Cycle 6) were added to ibrutinib, and patients were monitored serially for MRD starting on Cycle 3 Day 1. Once uMRD was achieved and confirmed 4 weeks later, patients entered a period of TFO. Patients who did not attain uMRD continued treatment for up to 24 cycles followed by TFO. The primary objective of the study was rate of uMRD, with a prespecified MRD conversion rate of 25% defined as promising. Secondary endpoints included safety and durability of clinical benefit after treatment discontinuation.
Results: In this fully accrued study, U2 was added to ibrutinib in 26 patients. Median age was 63 years (range, 48-81) and 77% were male. Disease characteristics included del(17p) in 8%, del(11q) in 12%, and unmutated IGHV in 31%. Median duration of ibrutinib treatment prior to addition of U2 was 22 months (range 7–66 months). The swimmer plot in Figure 1 depicts time on ibrutinib prior to enrolling in this study, the duration of treatment with triplet therapy, achievement of uMRD, and TFO.
MRD has been assessed in 24 patients; 71% (17/24) had uMRD in at least 1 assessment. Median time to first uMRD result was 5 months (range 2 – 12). A total of 16 patients (67%) entered TFO; 15 had 2 consecutive uMRD assessments and 1 completed 24 cycles with detectable MRD. TFO appears durable, with a median of 242 days off therapy (range 5-538 days) as of the data cutoff. 73% remain uMRD at last follow up. No patient has progressed or required re-treatment per iwCLL criteria.
U2 plus ibrutinib was well tolerated. All-causality grade 3/4 adverse events of special interest included ALT/AST increase (4%), diarrhea (4%), and hypertension (8%). Two patients discontinued all therapy due to rash; both were uMRD at the time of treatment discontinuation and remain uMRD. One patient died due to complications of COVID-19.
Conclusions: This is the first MRD-driven approach utilizing the combination of BTKi, PI3Ki, and anti-CD20 monoclonal antibody. This novel agent combination therapy was well tolerated and effective, with achievement of uMRD in 71% of evaluable patients. This “add-on” approach for patients on continuous ibrutinib resulted in deep remissions that allowed for a tailored, time-limited therapy and sustained treatment-free observation.
Disclosures: Roeker: AstraZeneca: Consultancy; Nurix: Consultancy; Abbott Laboratories: Current holder of individual stocks in a privately-held company; Beigene: Consultancy; Janssen: Consultancy; Loxo Oncology: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Aptose Biosciences: Research Funding; TG Therapeutics: Consultancy; AbbVie: Consultancy, Other: Prior holder of individual stocks in a privately-held company; Pharmacyclics: Consultancy; Vaniam group: Consultancy; Verastem: Consultancy. Leslie: Karyopharm Therapeutics: Honoraria, Speakers Bureau; TG Therapeutics: Consultancy, Honoraria, Speakers Bureau; Epizyme: Consultancy, Honoraria, Speakers Bureau; Abbvie: Consultancy, Honoraria; Merck: Consultancy; Janssen: Consultancy, Speakers Bureau; Kite, a Gilead Company: Consultancy, Honoraria, Speakers Bureau; ADC Therapeutics: Consultancy; BeiGene: Consultancy, Honoraria, Speakers Bureau; Seagen: Consultancy, Honoraria, Speakers Bureau; Celgene/BMS: Consultancy, Honoraria, Speakers Bureau; PCYC/Janssen: Consultancy, Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Speakers Bureau. Soumerai: Abbvie: Consultancy; Adaptive Biotechnologies: Consultancy; AstraZeneca: Consultancy; BeiGene: Consultancy, Research Funding; BMS: Consultancy; BostonGene: Research Funding; GlaxoSmithKline: Research Funding; Seattle Genetics: Consultancy; TG Therapeutics: Consultancy, Research Funding. Zelenetz: MorphoSys: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria, Research Funding; Verastem: Honoraria; BMS/Celgene/JUNO: Honoraria, Other; NCCN: Other; Gilead: Honoraria; LFR: Other; MEI Pharma: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Janssen: Honoraria; Beigene: Honoraria, Other, Research Funding; SecuraBio: Honoraria; Amgen: Honoraria; Pharmacyclics: Honoraria; MethylGene: Research Funding; Genentech/Roche: Honoraria, Research Funding; Novartis: Honoraria. Falchi: Abbvie: Consultancy, Research Funding; Roche: Research Funding; Genetech: Research Funding; Genmab: Consultancy, Research Funding. Park: Curocel: Consultancy; PrecisionBio: Consultancy; BMS: Consultancy; Minerva: Consultancy; Novartis: Consultancy; Affyimmune: Consultancy; Innate Pharma: Consultancy; Kite Pharma: Consultancy; Autolus: Consultancy; Kura Oncology: Consultancy; Servier: Consultancy; Amgen: Consultancy; Artiva: Consultancy; Intellia: Consultancy. Battiato: Janssen Pharmaceutical: Other: Advisory Board July 2020; Abbvie Pharmaceuticals: Other: CLL Steering Committee November 2020-present. Thompson: VJHemOnc: Honoraria; Curio Science: Honoraria; MJH Life Sciences: Honoraria. Miskin: TG Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Sportelli: TG Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Mato: Janssen: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; MSKCC: Current Employment; Adaptive Biotechnologies: Consultancy, Research Funding; BeiGene: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Nurix: Research Funding; AstraZeneca: Consultancy; Acerta/AstraZeneca: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Genmab: Research Funding; AbbVie: Consultancy, Research Funding; DTRM BioPharma: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Johnson and Johnson: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding.
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