Real-World Venetoclax-Obinutuzumab in 232 Treatment Naive CLL Patients: Feasibility and Tolerability

Fixed duration venetoclax-obinutuzumab (VO) is approved in treatment naïve (TN) chronic lymphocytic leukemia (CLL), based on CLL14 study addressed to patients (pts) with coexisting conditions. The combinations showed also to be effective and well tolerated in the younger population enrolled in the randomized CLL13 trial. The aim of this retrospective, multicenter Italian study is to evaluate the feasibility and tolerability of this combination in TN CLL in common clinical practice as well as reasons for choosing fixed-duration VO instead of continuous BTKi.

Consecutive pts receiving first-line therapy after VO approval/reimbursement in Italy (May 2022) were considered. Reasons for choosing the fixed duration treatment were recorded. The impact of clinical, biological, and demographic characteristics on VO feasibility (definitive treatment discontinuation and/or schedule modifications due to toxicity) and tolerability were analyzed. Debulking (Deb) phase (D1-D56) was separately evaluated to better understand its influence on treatment management. From May 2022 to June 2023, 790 treatment naïve continuous pts were treated with targeted agents in 49 centers. Treatment choice consisted of: continuous BTKi in 558 pts and fixed-duration VO in 232 (the latter representing the population of our analysis). The main reasons given by physicians for choosing VO instead of BTKi were: disease biology 46% (mutated IgHV status), fixed duration 33%, comorbidities 15%, patient choice 6%. Pts' characteristics are shown in Table 1. When considering Deb-phase (232 pts), VO was regularly administered according to the investigator brochure in 150 (64.7%). In 22 cases (9.5%) the schedule was a priori modified by clinicians: 12 pts started with V led-in and postponed O infusion at C2D1; in 10 planned O D8 and D15 infusions were omitted. Overall, 12 pts (5.2%) permanently discontinued VO due to toxicity. 3 of them dying due to: COVID pneumonia, invasive aspergillosis, VO-unrelated cachexia. In the remaining 48 (20.7%) schedule was adjusted due to AEs. Treatment modifications, overlapping in some cases were: 42 extended the Deb-phase (median days to completion 63, range 59-130); 14, never reached the full V dose; 31 did not perform the planned 5 O infusions (median 3 infusions, range 1-4). No age, neither coexisting conditions influenced treatment feasibility. The only parameters having an impact on Deb-phase discontinuation or schedule modifications due to toxicity were: baseline ANC<1500/mmc (OR 3.1, p=.035), hypogammaglobulinemia (OR 2.2, p=.018), concomitant use of anticoagulants (3.13, p=.029). Overall 23 pts (9.9%), including 7 categorized as high risk TLS, were hospitalized for treatment initiation. During Deb-phase grade 3-4 AEs occurred in 69 pts (30%): neutropenia (18%); thrombocytopenia (14%); infections (5%); IRR (5%). Development of any severe AE was influenced by: upper GI disorder, baseline neutropenia or thrombocytopenia. TLS was recorded in 13 pts (6%): 11 O-related and 4 V-related. All 4 clinical TLS were considered as secondary to O. Only high CLL-CI risk was associated with TLS. None of the baseline factors nor type of steroids premedication predicted IRR.

At the present follow-up of the 232 pts considered: 142 completed the 6 cycles of combinations treatment, 75 are still ongoing, 15 definitively discontinued treatment for AEs. Overall, 42 pts received VO with an adjusted schedule for toxicities: 22 are receiving V at reduced dose, 39 pts did not complete the planned O infusions (treatment modifications overlapping in some cases). G 3-4 toxicity developed in 78 pts being neutropenia and infections the most common reported. At univariate analysis factors affecting treatment feasibility were: presence of endocrine comorbidity; intermediate/high CLL-CI and hypogammaglobulinemia.

To our knowledge this is the first real-world study on clinical factors that may influence VO feasibility. Despite this setting of unselected population, most clinicians were adherent to VO schedule. A low rate of pts permanently discontinued therapy during Deb-phase with no impact of age or comorbidities on feasibility. Furthermore, TLS and IRR were in line with clinical trials. Longer follow-up data will be reported at the meeting allowing by multivariate analysis to better clarify the role of comorbidities on treatment management and the reproducibility of VO tolerability in common clinical practice.