EDINBURGH – Impaired renal function may indicate excess risk of tumor lysis syndrome (TLS) in venetoclax-treated chronic lymphocytic leukemia (CLL) patients and should be considered when assessing TLS risk, according to findings from a retrospective cohort study.
Complex karyotype may also affect TLS risk, Anthony Mato, MD, reported at the International Workshop on Chronic Lymphocytic Leukemia.
Of 339 CLL patients who were treated with venetoclax, 38%, 34%, and 28% were considered to have low, medium, or high risk for TLS, respectively, according to the standard definition based on absolute lymphocyte count as a measure of tumor burden and/or lymph node size.
TLS occurred in 35 patients (10%), including 26 cases of laboratory-confirmed TLS and 9 clinical TLS cases; 1 patient required dialysis and 1 death occurred, which was attributable to the TLS,of Memorial Sloan Kettering Cancer Center, New York, and colleagues reported in a poster at the workshop.
Univariate analysis was performed to “understand baseline factors associated with TLS development during dose escalation,” and it examined sex, creatinine clearance (CrCl), complex karyotype, immunoglobulin heavy chain variable mutation status, prior ibrutinib exposure, venetoclax monotherapy vs. combination therapy, and TLS risk group. The investigators observed no significant difference between the low- and medium-risk patients, therefore those two groups were combined and compared with the high-risk patients.
The univariate analysis showed significant associations between TLS and CrCl (odds ratio, 2.9 for 80 mL/min or less vs. greater than 80 mL/min), complex karyotype (OR, 2.2), and low/medium vs. high TLS risk based on the standard definition (OR, 2.56).
A multivariable analysis of the predictors identified as significant in the univariate analyses showed that standard TLS risk group and CrCl remained independent predictors of TLS.
“Although the odds ratio for complex karyotype suggested potential clinical significance, this did not meet the threshold for statistical significance and was not included in the final model,” they wrote.
The area under the receiver operating characteristic curve for a model including TLS risk group and CrCl was 74.6%, compared with 65% for the area under the ROC curve using the standard tumor burden/lymph node size approach for defining TLS risk, which is described in the venetoclax package insert.
Patients included in the study had a median age of 67 years at venetoclax initiation, 69% were men, 85% were white, and 13% were treated on a clinical trial. Complex karyotype was present in 39%, del(17p) in 43%, and 84% had immunoglobulin heavy chain variable–unmutated disease.
Most patients received venetoclax monotherapy (79%), had relapsed/refractory disease (94%), and had previously received ibrutinib (78%). The median number of prior therapies was 3, but the number ranged from 0-15, the investigators noted.
The findings of this study suggest that, in addition to defining risk based on absolute lymphocyte count and lymph node size, patients with CrCl less than 80 mL/min – indicating impaired renal function – have excess risk of TLS.
Although complex karyotype did not reach statistical significance as an independent predictor of TLS, the findings in this study suggest it “may impact TLS risk and is worthy of further study in larger samples,” they said, concluding that consideration of baseline renal function, and possibly karyotype, could “further guide practitioners in their approach to prophylaxis and patient counseling, allowing for improved safety in the use of this effective agent in CLL.”
Additional planned analyses will focus on TLS risk score development and further refinement of TLS risk stratification, they noted.
Dr. Mato has received grant support, consulting fees, and/or fees for serving on a data and safety monitoring board or advisory board from AbbVie, AstraZeneca, Celgene, Janssen, TG Therapeutics, Pharmacyclics, Loxo, Sunesis, prIME Oncology, Pfizer, Johnson & Johnson, and Regeneron.