Safety and Efficacy of Venetoclax-Based Treatment in Elderly CLL Patients: A Retrospective Study from the Filo Group

Median age at diagnosis of chronic lymphocytic leukemia is 72 years. However, only few patients over 80 years of age are included in clinical trials, even in those devoted to unfit patients. In order to evaluate both efficiency and safety of venetoclax in this category of patients, we conducted a multicentric retrospective study and collected data from 77 CLL patients from 19 FILO centers who started venetoclax after 80 years of age.

Median age at venetoclax initiation was 86 years old (81-97). 63% of patients had a history of heart disease, 62% had renal failure (moderate 59% and severe 3%) and 29% had a history of severe infections. Despite their comorbidities and a CIRS greater than 6 in 70% of cases, their autonomy was preserved with a median performans status of 1 (0-4). In this comorbid geriatric population, pretherapeutic geriatric assessment was only performed in a single patient. The median number of prior therapies was 2 (0-6) with an exposure to a BCR inhibitor in 56% of cases. 11q and 17p deletion were found in 39% and 30% of cases respectively, 39% of patients had a complex karyotype and 30% harbored a TP53 mutation. However, in this real life population, these prognostic factors were only performed in half of patients. IGHV mutational status was only available in 11 patients, and 83% of them had unmutated IGHV. At the time of venetoclax initiation, the tumor lysis syndrome (TLS) risk was moderate in 57% of cases and high in 8% of cases. Venetoclax was administered as a single agent (42%) or in association with rituximab (58%). In total, half of the patients were hospitalized at each dose ramp-up, and only 3 patients were treated on outpatient basis. 82% of the cohort was able to reach the daily dose of 400mg. Half of the patients were included in a phone call monitoring program with oncology nurses to pre-emptively manage side effects and foster therapy adherence. The safety study reported 14% of TLS, with 2 discontinuations of treatment within the first month: one of which led to dialysis and the other to death. As in the previously published studies, 25% of patients had infectious complications, and grade 3 haematological and digestive toxicities were reported in 42% and 22% of cases, respectively. The reduction of the daily dose of venetoclax was necessary for 33%. Permanent discontinuation of venetoclax occurred in 40% of subjects, including 29% of early withdrawal (within the first 3 months). Main reasons for discontinuation were intolerance (21%), CLL progression (21%), death (21%) and scheduled treatment discontinuation (10%). The overall response rate was 86%, consisting of 49% of complete response (unconfirmed by bone marrow biopsy) and 37% of partial response. With a median follow-up of 21months, estimated progression free survival and overall survival were 29 and 38 months respectively. Prior exposure to a BCR inhibitor had no impact on progression free survival.

To conclude, venetoclax has a manageable safety profile in elderly patients with comorbidities and can induce prolonged responses. Finally, if additional follow-up by oncology nurses seems to be more and more implemented, the pre-therapeutic onco-geriatric evaluation remains underexploited in this population.