A less cumbersome venetoclax initiation and subsequently increased access to this orally administered B-cell lymphoma 2 (BCL2) inhibitor may be possible for patients with chronic lymphocytic leukemia (CLL) and low disease burden. These findings were presented in a poster at the 2021 American Society of Hematology (ASH) Annual Meeting.

Venetoclax is FDA approved and has been shown to provide durable responses. However, an elevated risk of tumor lysis syndrome (TLS) upon venetoclax initiation requires following a strict dose titration schedule with frequent laboratory testing. The researchers sought to review the real-world situation and see how it holds up to the package insert guidelines. 

They enrolled 73 consecutive patients (64% male, 79% white) with CLL who were initiated on venetoclax between July 2017 and March 2021. Compliance criteria were strict and required patients to adhere to all laboratory checks at the various time points. Patients were considered noncompliant if they missed even a single lab test or time point.

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Ramp up dosing and laboratory testing for TLS (creatinine, potassium, calcium, phosphorous, and uric acid) during the first 2 weeks of treatment with venetoclax occurred in 66% (48) of patients.

In this cohort, 49% of patients were categorized as having low tumor burden, 44% as having medium tumor burden, and 6% as having high tumor burden. Compliance rates varied according to tumor burden (75% in high, 66% in medium, and 67% in low).

Six (8%) patients required interventions, with all interventions occurring in the medium or high tumor burden groups. None of the 73 patients with CLL required rasburicase administration, renal replacement therapy, emergency department visits, unplanned hospitalizations, or intensive care unit admissions; and no deaths occurred during the venetoclax ramp up.

This real-world study suggests that strict monitoring for TLS during venetoclax initiation may not be universal and may be due, in part, to institutional barriers. Intervention rates in this analysis were low during the first 2 weeks and no patients with a low tumor burden required an intervention.

The researchers concluded that a less strict laboratory monitoring schedule may be acceptable in patients with low tumor burden. However, they cautioned that a prospective study is needed to confirm these findings.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a complete list of authors’ disclosures.


Matuszfisher A, Bose R, Boselli D, et al. Very few interventions after tumor lysis monitoring in patients with chronic lymphocytic leukemia who are started on venetoclax in the real-world setting– suggests less intensive monitoring maybe safe for low-risk patients. Presented at ASH 2021; December 11-14, 2021. Abstract 1557.