Conference Coverage

Relapsed MCL: Options for treatment


 

EXPERT ANALYSIS FROM MHM 2018

Bruton’s tyrosine kinase (BTK) inhibitors are particularly useful in the setting of relapsed mantle cell lymphoma, according to Kristie A. Blum, MD.

Dr. Kristie A. Blum of Emory University

Dr. Kristie A. Blum

Venetoclax and lenalidomide can also be considered in the relapsed mantle cell lymphoma (MCL) setting, Dr. Blum, a professor in the department of hematology and medical oncology at Emory University in Atlanta, said at the American Society of Hematology Meeting on Hematologic Malignancies.

“I tend to favor BTK inhibitors as my first line of therapy,” she said, later qualifying that this applies when clinical trial enrollment is unavailable.

Ibrutinib

The BTK inhibitor ibrutinib is well established as a treatment for MCL and for use in the relapsed setting, she said, noting that pooled data from the phase 2 CYC-1104 trial, the phase 2 MCL 2001 (SPARK) trial, and the phase 3 MCL3001 (RAY) trial showed an overall response (OR) rate of 66% in 370 patients and a complete response (CR) rate of 20%.

The median duration of response (DOR) was 18.6 months, median progression-free survival (PFS) was 12.8 months, and median overall survival (OS) was 25 months (Br J Haematol. 2017 Nov;179[3]:430-8).

Adding rituximab to ibrutinib (R-ibrutinib) improved outcomes, at least in one single center phase 2 trial of 50 relapsed patients with a median of three prior therapies, she said. The OR rate in that study was 88%, and the CR rate was 58% (Br J Haematol. 2018 May;182[3]:404-11).

“What was really impressive to me was that the median duration of response was about 46 months. PFS was 43 months, and patients were on [treatment] as long as 56 cycles,” she said.

Acalabrutinib

The newer BTK inhibitor acalabrutinib also shows benefit in the relapsed MCL setting, Dr. Blum said.

In a recent multicenter, open-label, phase 2 study of 124 patients with a median age of 68 years and a median of two prior therapies, acalabrutinib at a dose of 100 mg twice daily was associated with an OR rate of 81% and a CR rate of 40% (Lancet. 2018 Feb 17;391:659-67).

“Seems a little better than what you’d expect with single agent ibrutinib,” she said, noting that median DOR and PFS have not been reached in that study.

The main toxicities have been “headache and some diarrhea,” but follow-up is currently only about 15 months, she added.

Venetoclax

Another option in this setting is the B-cell lymphoma 2 (BCL-2) inhibitor venetoclax, which was shown in a recent phase 1 study of patients with various lymphoma subtypes to have activity in relapsed MCL, Dr. Blum said.

The OR rate in 28 relapsed MCL patients in that study was 75%, and the median PFS was 14 months (J Clin Oncol. 2017 Mar;35:826-33).

Additionally, an “intriguing combination study of venetoclax and ibrutinib” was recently published in the New England Journal of Medicine, she noted.

That study included only 23 patients with relapsed MCL, but they were a “pretty high-risk” group with a median age of 68 years, about half having a TP53 abnormality, and 30% having a prior transplant.

The OR and CR rates at 16 weeks by positron emission tomography were 71% and 62%, respectively (N Engl J Med. 2018 Mar 29;378:1211-23).

“Actually, about 40% achieved [minimal residual disease] negativity, but this was only checked in about half the patients,” she said. “So this is an intriguing combination and hopefully something we’ll see more of in the upcoming years.”

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