CHICAGO – A chemotherapy-free regimen has produced promising early response and survival outcomes in patients with a particularly poor-prognosis subtype of diffuse large B-cell lymphoma, an investigator reported at the annual meeting of the American Society of Clinical Oncology.
The overall response rate was 86% after two cycles of combined rituximab, lenalidomide, and ibrutinib – or RLI – in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) of the non–germinal center (non-GCB) subtype, said Jason Westin, MD, of the department of lymphoma/myeloma at the University of Texas MD Anderson Cancer Center in Houston.
The response rate increased to 96% after subsequent cycles of RLI plus standard chemotherapy, said Dr.Westin, who added that the rates of progression-free and overall survival at 1 year were also 96% in the investigator initiated, single-arm, open-label, phase 2 study, called Smart Start.
That looks quite favorable, compared with what’s been achieved in previous studies in this poor-prognosis group of patients, Dr. Westin said during a podium presentation of Smart Start data, though he cautioned against direct comparison to historical studies and added that further follow-up is needed.
“Our survival outcomes appear excellent with about a year’s worth of follow-up,” he said during his presentation. “I’d say the novel/novel combinations, with and without chemotherapy, are feasible for large cell, and next step studies are warranted.”
Jasmine M. Zain, MD, of City of Hope Comprehensive Cancer Center, said these results so far raise the possibility of an effective chemotherapy-free treatment regimen for aggressive lymphomas.
“This regimen, particularly for non-GCB subtypes, is extremely promising,” Dr. Zain said during a podium discussion of the study. “I think we were all oohing and aahing over the results, and it could possibly even be practice changing.”
Moving to a nonchemotherapy regimen could raise new questions for treatment of non-GCB and possibly also GCB subtypes of DLBCL, such as when the treatments could be stopped, or whether a maintenance approach would be useful, she added.
The Smart Start study enrolled a total of 60 patients with non-GCB DLBCL. The patients received RLI for two 21-day cycles, followed by another six cycles of RLI plus chemotherapy, which was either EPOCH or CHOP, at the investigators’ discretion.
“With a median follow-up of 362 days, we’ve had three progression events,” Dr. Westin said in his discussion of the preliminary efficacy results.
Adverse events were similar to what would be expected for standard chemotherapy, according to Dr. Westin, except for rash, which was seen mainly in cycles one and two.
There were two deaths on study protocol, including one fatal fungal infection that investigators attributed to high dose corticosteroids and RLI. There were no subsequent fungal infections after a protocol amendment prohibiting corticosteroids during the RLI-only cycles, according to the investigators’ report.
The high response rates following the initial lead-in phase made investigators wonder what would happen without subsequent chemotherapy, Dr. Westin told attendees during his oral presentation. In one case, a 74-year-old man did complete the two lead-in cycles of RLI and declined further therapy.
“He’s now nearly 2 years out, without any additional therapy, and has not relapsed to date,” Dr. Westin said. “This is, again, with 6 weeks worth of RLI therapy.”
Final results and minimal residual disease data from the Smart Start study will be presented at a conference later in 2019, Dr. Westin said.
The study received research support and funding from the ASCO Conquer Cancer Foundation. The trial drug and support were provided by Celgene and Janssen. Dr. Westin reported disclosures related to Celgene, Genentech/Abbvie, Kite Pharma, Kite/Gilead, Novartis, ProNAi, Spectrum Pharmaceuticals, Bristol-Myers Squibb, Janssen, and Karyopharm Therapeutics.
SOURCE: Westin J et al. ASCO 2019, Abstract 7508.