ORLANDO – Updated trial results have revealed durable responses with venetoclax and ibrutinib in patients with mantle cell lymphoma (MCL), allowing some patients to stop treatment.
Five of 24 patients were able to stop treatment after achieving minimal residual disease (MRD)-negative complete responses (CRs). Four of these patients remain in CR at up to 18 months off treatment, although one patient ultimately progressed and died.
“Treatment cessation was feasible for patients in MRD-negative complete responses, raising the prospect of limited-duration, targeted-agent therapy in the management of relapsed/refractory mantle cell lymphoma,” said Sasanka M. Handunnetti, MBBS, of Peter MacCallum Cancer Centre in Melbourne. Dr. Handunnetti presented these results, from the, at the annual meeting of the American Society of Hematology.
The phase 2 trial enrolled 24 patients. At baseline, patients had a median age of 68 years (range, 47-81 years), and 88% were men. One patient was treatment-naive, but the rest had relapsed/refractory MCL. These patients had received a median of two prior therapies (range, 1-6).
The patients received venetoclax at 400 mg daily and ibrutinib at 560 mg daily.
In the primary analysis, the CR rate was 62% at week 16 and 71% overall, according to positron-emission tomography/computed tomography. MRD negativity was achieved by 67% of patients according to flow cytometry and 38% according to allele-specific oligonucleotide polymerase chain reaction (
Response and survival
For the current analysis, the median follow up was 37.5 months (range, 1.4-45.3 months). The median duration of response has not been reached, the median progression-free survival is 29 months, and the median overall survival is 32 months.
Thirteen patients have died, 8 of them due to progressive disease. The remaining 11 patients are still alive, and 9 of them are still in CR. One patient is still in partial response, and one has not responded but remains on ibrutinib and venetoclax.
Dr. Handunnetti pointed out that 12 patients had TP53 aberrations, and 8 of them died, but 4 remain alive and in CR. All four patients with SMARCA4 aberrations died.