In first-line patients (n = 29) and relapsed/refractory patients (n = 45) with TP53 mutations, complete response rates were 55% and 58%, respectively, reported hematologist-oncologist Michael Wang, MD, of the University of Texas MD Anderson Cancer Center, and colleagues, at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.
“These results are encouraging in light of the poor responses and shorter survival outcomes with standard chemotherapy,” Dr. Wang said in an ASCO presentation.
The current standard of care for relapsed/refractory MCL includes Bruton tyrosine kinase inhibitors for first relapse and CAR T-cell therapy (CAR-T) for second relapse in eligible patients or pirtobrutinib (Jaypirca) in patients ineligible for CAR T-cell therapy, Ohio State University Comprehensive Cancer Center hematology specialist Narendranath Epperla, MD, MS, said in an interview. Dr. Epperla is familiar with the new study findings but didn’t take part in the research.
Options for third relapse and beyond include clinical trial, rituximab [Rituxan] and lenalidomide [Revlimid], and bortezomib [Velcade],” Dr. Epperla said. “Venetoclax is not currently FDA-approved but can also be considered at third relapse.”
Better therapies are needed for a number of reasons, including poor outcomes in high-risk patients, such as those with TP53 mutations and those who progress following CAR T, Dr. Epperla said. Also, “as the novel agents are being moved into earlier lines of therapy, there remains an unmet need in those who progress on these agents with fewer options in the relapsed setting.”
At last December’s American Society of Hematology annual meeting, Dr. Wang and colleagues reported on the primary analysis results from the Sympatico study. Patients with relapsed/refractory MCL after 1-5 prior therapies were randomly assigned to receive 560 mg of ibrutinib once daily with either placebo (n = 133) or 400 mg daily of venetoclax after ramp-up (n = 134) for 2 years. Then subjects continued taking ibrutinib alone until their disease progressed or they reached unacceptable toxicity.
At a median follow-up of 51.2 months, median progression-free survival was longer in the ibrutinib-venetoclax group vs. ibrutinib alone (hazard ratio [HR] = 0.65, 95% CI, P = .0052).
The new analysis pools several cohorts of patients with TP53 mutations who all took the combination therapy: 5 from a safety run-in phase, 40 from the randomized phase, and 29 from a first-line cohort (median age at baseline = 67).
Median overall survival was not reached in the first-line group and 35.0 months in the relapsed/refractory group (total = 47.1 months). Median progress-free survival in the groups was 22.0 months and 20.9 months, respectively, and median duration of response was 20.5 months and 26.5 months, respectively.
With regard to the new findings, “it is good to see the responses with ibrutinib and venetoclax were deep and durable,” Dr. Epperla said. The combination treatment “provides a good alternative option for TP53-mutated MCL patients who are ineligible for CAR-T.”
Dr. Epperla added that the findings about the addition of ibrutinib could apply to newer-generation Bruton tyrosine kinase inhibitors that have relatively better safety profiles.
However, Dr. Epperla cautioned that the treatment needs to be weighed against the toxicity and cost of the regimen of ibrutinib and venetoclax for 2 years then single-agent ibrutinib until progression or unacceptable toxicity.
This news organization reported in 2023 that estimated net spending on ibrutinib per Medicare data increased by nearly half from 2014-2020, reaching $11,980 in 2020 vs. $7,787 for venetoclax.
Dr. Epperla also noted that “there are newer therapies that are emerging, such as T-cell-engaging bispecific antibodies, and they have shown promising results.”
In an interview, Brad S. Kahl, MD, a hematologist-oncologist at Washington University, St. Louis, said the improvement in outcomes are “modestly significant.”
Dr. Kahl, who is familiar with the study findings but didn’t take part in the research, said it is “worth adding the venetoclax, particularly in these biologically high risk patients with p53 mutations. Venetoclax is not FDA-approved, so insurance approval will need to be determined on a case-by-case basis. The combination is very expensive.”
Dr. Kahl agreed with Dr. Epperla that the findings could be extrapolated to other Bruton tyrosine kinase inhibitors.
The study was funded by Pharmacyclics, an AbbVie Company. Dr. Epperla disclosed relationships with BeiGene and Eli Lilly. Dr. Kahl reported ties with AstraZeneca, BeiGene, Abbvie, and Genentech.