Conference Coverage

Efficacy of postvenetoclax therapy may depend on prior agent exposure in CLL



– For a patient with chronic lymphocytic leukemia (CLL) who has discontinued venetoclax, choosing the best next therapy may depend on what novel agents the patient was exposed to and why they discontinued them, according to Anthony R. Mato, MD, with the Center for CLL at Memorial Sloan Kettering Cancer Center in New York.

Dr. Anthony Mato of Memorial Sloan Kettering Cancer Center in New York Andrew D. Bowser/MDedge News

Dr. Anthony Mato

If the patient is Bruton tyrosine kinase (BTK) inhibitor naive, then use of a BTK inhibitor after venetoclax would be supported, Dr. Mato said, by the high overall response rates and durable remissions that he and his coinvestigators documented in a retrospective, multicenter study designed specifically to address the gap in knowledge regarding what to use after venetoclax.

If the patient is BTK inhibitor exposed, then the reason for discontinuation needs to be considered before going with that venetoclax-to-BTK inhibitor sequence, Dr. Mato said during an oral presentation at the annual meeting of the American Society of Hematology.

“In patients with resistance to a BTK inhibitor, the sequence was not supported – it did not appear to be effective,” he said. “However, in the setting of intolerance, an alternate BTK inhibitor could be considered.”

The study did not support a venetoclax-to-PI3K inhibitor sequence in PI3K-naive patients, he added, noting that remissions did not appear to be durable, suggesting a potential overlap in resistance mechanisms between agents.

All told, the most effective therapies for in the postvenetoclax setting included the use of a BTK inhibitor in BTK inhibitor–naive or previously responsive patients, and allogeneic transplant following double novel-agent exposure.

“These data may provide support for venetoclax’s earlier use in the course of CLL, and may guide clinical practice and aid in the design of future clinical trials to address sequencing of novel agents,” Dr. Mato told attendees.

While prospective and real-world data clearly show that venetoclax is active in ibrutinib- or idelalisib-exposed patients, data are conversely “variable and limited” with regard to outcomes for next therapies following venetoclax.

“Current data addressing this key sequencing question, I feel, is a major limitation in supporting the sequence of venetoclax to a BTK inhibitor,” Dr. Mato said.

Accordingly, Dr. Mato and colleagues at 31 centers internationally planned and conducted this study, which included data on 326 patients treated with venetoclax who then discontinued for any reason.

“I wanted to highlight that 50% of the sites for this trial were recruited by a single tweet,” said Dr. Mato, adding that he and his coauthors received no funding to conduct this study and volunteered their time to complete it.

They found that, in BTK inhibitor–naive patients who discontinued venetoclax, subsequent BTK inhibitor treatment was associated with a high overall response rate and durable remissions, with a median progression-free survival (PFS) of 32 months.

In BTK inhibitor–exposed patients, response to postvenetoclax BTK inhibitor treatment depended on the reason for discontinuation, with a favorable result (PFS not reached with a mean follow-up of 7.7 months) in patients who were intolerant of the prior BTK inhibitor. By contrast, median PFS was only about 4 months for patients who were resistant to the prior BTK inhibitor.

PI3K inhibitors did not produce durable remissions after venetoclax, with a median PFS also of just 4 months, Dr. Mato reported.

However, cellular therapies appeared to be effective after venetoclax. Allogeneic hematopoietic stem cell transplantation was particularly effective, with the median PFS not reached, while chimeric antigen receptor T-cell therapy produced a PFS of 9 months.

Dr. Mato emphasized that the results of the retrospective trial were “hypothesis generating” and noted that patients in the study had received a median of 3, and up to 11, prior therapies. “This population are probably not our patients receiving venetoclax in clinical practice. They’re more heavily pretreated.”

Dr. Mato reported disclosures related to Gilead, AstraZeneca, AbbVie, Sunesis, Johnson & Johnson, TG Therapeutics, Loxo Oncology, DTRM Biopharma, Genentech, Janssen, Acerta Pharma, Pharmacyclics, and Celgene.

SOURCE: Mato AR et al. ASH 2019, Abstract 502.

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