Venetoclax Re-Treatment of Chronic Lymphocytic Leukemia (CLL) Patients after a Previous Venetoclax-Based Regimen
Authors: Thompson Meghan C. , Allan John N. , Sail Kavita , Manzoor Beenish S. , Pu Jeffrey J. , Barr Paul M. , Coombs Catherine C. , Schuster Stephen J. , Skarbnik Alan , Rhodes Joanna M , Barrientos Jacqueline C. , Roeker Lindsey E , Leslie Lori A. , Kamdar Manali , Choi Michael Y. , Simkovic Martin , Lansigan Frederick , Hale Brittany Jane , Zelenetz Andrew D , Moskowitz Alison J. , Bantilan Kurt S. , Komari Celina J. , Goy Andre H. , Feldman Tatyana A. , Furman Richard R. , Mato Anthony R. 
Published: February 2021

BACKGROUND:
Treatment of chronic lymphocytic leukemia (CLL) with a fixed-duration venetoclax (Ven)-based regimen is now a standard of care (SOC) option for both frontline and relapsed refractory (R/R) disease based on results of the CLL14 and MURANO trials (Fischer et al NEJM 2019, Seymour et al NEJM 2018). As fixed-duration Ven regimens are now a SOC, it is expected that an increasing number of patients (pts) will ultimately progress after Ven exposure and require additional CLL-directed therapy. While many discuss re-treatment with Ven as a subsequent treatment option, the current literature contains response data on an extremely limited number of evaluable pts (11 pts MURANO, overall response rate (ORR) 55%; 3 pts VEN 365, ORR 100%). Whether re-treatment with Ven is an acceptable option remains an important unanswered clinical question.
METHODS:
We conducted a multicenter, retrospective study of CLL pts treated with a Ven-based regimen (Ven1) and then re-treated with a second Ven-based regimen (Ven2) in a later line of therapy (LOT). Data were collected from 13 centers and the CLL Collaborative Study of Real-World Evidence database. CLL pts were eligible for inclusion if they were treated with a Ven-based regimen in any LOT and then re-treated with a Ven-based regimen as a later LOT. Collected data included demographics, prognostic disease characteristics, tumor lysis syndrome (TLS) risk and incidence, clinical response and reasons for treatment discontinuation (dc). The primary study endpoint was investigator-assessed ORR (CR: complete response, PR: partial response, SD: stable disease, PD: progression of disease, iwCLL 2018). Kaplan-Meier method was used to estimate progression free survival (PFS). All other analyses were descriptive.
RESULTS:
We identified 25 pts who were re-treated with Ven. Pt characteristics prior to treatment with Ven1 are summarized in Table 1. In 24% of pts (n=6), Ven1 was administered as part of a clinical trial. Median prior LOT was 2 (range 0-10) with 12.0% treatment naïve and 60% with prior BTKi exposure. The majority of pts had ≥1 high-risk prognostic marker: del17p (39%), TP53 mut (27%), complex karyotype ≥5 abnormalities (30%) and unmutated IGHV (84%). For Ven1, treatment regimens, TLS risk, and dose are summarized in Table 2.
With a median duration of exposure of 15 months (mos) (64% pts &gt; 12 mos) for Ven1, the ORR was 88% (CR: 48%, PR: 40%, Figure 1A). Ten pts had minimal residual disease (MRD) assessments by flow cytometry; 8 pts (80%) achieved undetectable MRD (10^-4). Most common reasons for Ven1 dc included: toxicity (28%), completion of planned therapy (24%), MD/pt preference (24%), other (12%), alloHSCT (4%) and cost (4%).
There was a median of 8.7 mos (36% &gt; 12 mos) between Ven1 and the initiation of Ven2, and 88% did not receive another LOT between Ven1 and Ven2. Reasons for Ven2 initiation were either CLL progression (87.5%) or MRD-positive relapse (12.5%). For Ven2, TLS risk, TLS incidence and dose information are outlined in Table 2. TLS was a rare event during Ven re-treatment (4.5%, lab only). For Ven2, Ven monotherapy was the most common regimen (52%). Standard Ven dose-escalation was used for re-initiation in 17 of 19 pts with available data, however 1 pt started Ven2 at 400 mg daily (no TLS) and another underwent a prolonged ramp-up period.
At the time of this analysis, 18 pts had available response assessments for Ven2: ORR is 72.2% (CR: 4, PR: 9, SD: 4 and PD: 1, Figure 1B). Median time from Ven2 to progression or last follow up is 8 mos (0.2-29 mos). Median PFS has not been reached. Estimated 12-month PFS is 69.1%. For pts with a CR to Ven2, median follow up time is 14.5 mos vs 7 mos for pts with PR or SD. Of 25 pts re-treated with Ven, 68% remain on Ven2 presently and 32% have discontinued Ven2, including due to CLL progression (n=4), completion of planned therapy (n=1), unrelated death (n=1), MD/pt preference (n=1).
CONCLUSIONS:
To our knowledge, this is the largest reported cohort of CLL pts re-treated with Ven after a prior Ven-based regimen. The high ORR in this pt population (median 2 prior therapies) suggests that re-treatment is a promising strategy and should be considered in treatment sequencing algorithms. Notably, pts with a CR to Ven2 had a longer median follow up than those with a PR or SD, suggesting a likelihood of deeper responses with time. Given the promising ORR, further research to prospectively validate Ven re-treatment is warranted. Updated data will be presented.

Disclosures
Allan: Celgene, Genentech, Janssen, TG Therapeutics: Research Funding; Abbvie, Janssen, AstraZeneca, Pharmacyclics: Honoraria; Acerta, Genentech, Abbvie, Sunesis, Ascentage, Pharmacyclics, Janssen, AstraZeneca, BeiGene: Consultancy. Sail:AbbVie Inc.: Current Employment, Current equity holder in publicly-traded company. Manzoor:Abbvie: Current Employment, Other: may hold stock or stock options. Pu:Takeda Pharmaceuticals: Consultancy. Barr:Gilead: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy, Research Funding; Abbvie/Pharmacyclics: Consultancy, Research Funding; Verastem: Consultancy; Morphosys: Consultancy; TG therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; Celgene: Consultancy; Merck: Consultancy; Genentech: Consultancy. Coombs:LOXO Oncology: Honoraria; MEI Pharma: Honoraria; Abbvie: Consultancy, Honoraria; Genentech: Honoraria; AstraZeneca: Honoraria; Octapharma: Honoraria; Novartis: Honoraria. Schuster:AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria; Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding. Skarbnik:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Consultancy; Beigene: Speakers Bureau; Verastem: Speakers Bureau; Novartis: Speakers Bureau; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CLL Society: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rhodes:Verastem: Consultancy; Abbvie/Genentech: Consultancy; Pharmacyclics: Consultancy; AstraZeneca: Consultancy. Barrientos:Janssen: Honoraria; Sandoz: Consultancy; Oncternal Therapeutics: Research Funding; Bayer: Consultancy; Genentech: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy. Roeker:American Society of Hematology: Research Funding; Abbott Laboratories: Other: spouse with minority ownership interest ; AbbVie: Other: spouse with minority ownership interest . Leslie:Celgene: Speakers Bureau; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; KitePharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Epizyme: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; ADC therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kamdar:Roche: Research Funding. Choi:Pharmacyclics/Abbvie: Research Funding; Genentech: Consultancy. Simkovic:Abbvie: Consultancy, Other: travel expenses. Lansigan:Seattle Genetics: Consultancy; BMS: Consultancy; BMS Steering Committee for MAGNIFY Program: Membership on an entity's Board of Directors or advisory committees; Spectrum Pharma: Consultancy, Research Funding. Zelenetz:Novartis: Consultancy; Gilead: Research Funding; Janssen: Consultancy; Celgene: Consultancy; Gilead: Consultancy; Genentech/Roche: Consultancy; Roche: Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnology: Consultancy; MorphoSys: Research Funding; Amgen: Consultancy; Sandoz: Research Funding; Celgene: Research Funding; MEI Pharma: Research Funding. Moskowitz:Merck: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Miragen Therapeutics: Consultancy; Incyte: Research Funding; Merck: Consultancy; Imbrium Therapeutics, L.P.: Consultancy; Seattle Genetics: Consultancy. Goy:Morphosys: Research Funding; AbbVie: Research Funding; MD Anderson: Research Funding; Regional Cancer Care Associates/OMI: Current Employment; Infinity Verastem: Research Funding; Infinity: Research Funding; Karyopharm: Research Funding; Genentech/Roche: Research Funding; CALBG: Research Funding; Constellation: Research Funding; Bayer: Research Funding; PracticeUpdate Oncology: Consultancy; RCCA/OMI: Current Employment; Acerta: Consultancy, Honoraria, Other: leadership role, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: leadership role, Research Funding; Celgene: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: leadership role, Research Funding; COTA: Consultancy, Current equity holder in publicly-traded company, Other: leadership role; Kite, a Gilead Company: Consultancy, Current equity holder in publicly-traded company, Honoraria, Other: leadership role, Research Funding; Xcenda: Consultancy; Hackensack UMC and University of Nebraska: Research Funding. Feldman:Pfizer: Research Funding; Kyowa Kirin: Consultancy, Research Funding; Eisai: Research Funding; Cell Medica: Research Funding; Amgen: Research Funding; Pharmacyclics: Honoraria, Other, Speakers Bureau; Abbvie: Honoraria; Bayer: Consultancy, Honoraria; Trillium: Research Funding; Portola: Research Funding; Janssen: Speakers Bureau; AstraZeneca: Consultancy; Viracta: Research Funding; Rhizen: Research Funding; Corvus: Research Funding; BMS: Consultancy, Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; Celgene: Honoraria, Research Funding; Takeda: Honoraria, Other: Travel expenses; Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau. Furman:Verastem: Consultancy; Genentech: Consultancy; Beigene: Consultancy; AstraZeneca: Consultancy, Research Funding; Acerta: Consultancy; Abbvie: Consultancy; TG Therapeutics: Consultancy, Research Funding; Sunesis: Consultancy; Pharmacyclics: Consultancy; Oncotarget: Consultancy; Loxo Oncology: Consultancy; Janssen: Consultancy, Speakers Bureau; Incyte: Consultancy. Mato:Genentech: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; BeiGene: Consultancy; LOXO: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Adaptive: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding.