Amsterdam – For patients with untreated mantle cell lymphoma (MCL), the anti-CD20 monoclonal antibody obinutuzumab may one day offer an alternative to rituximab, according to investigators.
Patients in the LYMA-101 trial were given four cycles of obinutuzumab in combination with dexamethasone, high-dose aracytine, and platinum chemotherapy (O-DHAP), followed by autologous stem cell transplantation (ASCT) and maintenance obinutuzumab. After a median follow-up of 14.6 months, ranging from 3.8 to 24.4 months, 85% of evaluable patients had achieved minimal residual disease (MRD) in bone marrow, reported lead author Steven Le Gouill, MD, PhD, of the University Hospital of Nantes, and his colleagues.
In this disease population, an MRD rate of 85% is “unprecedented,” Dr. Le Gouill said during his presentation at the annual congress of the European Hematology Association. Based on findings from LYMA-101 and preclinical data, Dr. Le Gouill suggested that obinutuzumab may become an alternative to rituximab, the current standard anti-CD20 antibody.
“There are few data of interest for obinutuzumab in MCL, but there is a strong rationale in the lab as obinutuzumab has a different mechanism of action against tumor cells [than rituximab], with more efficacy against MCL cells,” Dr. Le Gouill said.
Data from the ongoing phase 2 trial were drawn from 85 patients with untreated MCL who were 65 years or younger at the time of enrollment. More specifically, median patient age was 55.5 years and 17.4% of patients had blastoid disease. All patients were given the O-DHAP/ASCT/obinutuzumab protocol, with a maintenance period of 3 years. Thereafter, MRD-positive patients may receive obinutuzumab on-demand.
The primary endpoint was MRD in bone marrow after induction therapy, measured by quantitative PCR (qPCR) and droplet digital PCR (ddPCR). Secondary endpoints included response rates, survival measures, incidence of stem cell collection failure after O-DHAP, and MRD rates at additional therapeutic time points.
Owing to the ongoing nature of the study, Dr. Le Gouill focused on the primary endpoint during his presentation.
Analysis showed that 75% and 85% of evaluable patients had achieved negative MRD in bone marrow after induction, according to qPCR and ddPCR, respectively.
These early findings give “a flavor of the results in terms of efficacy,” Dr. Le Gouill said, noting that “the median follow-up is pretty short.”
Still, 1-year findings were “very promising,” he said, with a progression-free survival of 93.4% and overall survival of 96%.
Twelve patients stopped treatment before ASCT, three prior to maintenance, and nine during maintenance. Of these 24 patients, 13 stopped treatment because of adverse events. The remaining 11 patients halted therapy because of disease progression, other malignancies, or death.
From the original 85 patients, 3 patients died and 3 progressed. Considering all of these findings, and that no major toxicities were encountered, the investigators concluded that the regimen was safe.
Overall, the results suggest that further research is needed, Dr. Le Gouill concluded. “Maybe this is where obinutuzumab may have stronger efficacy in MCL, as compared to rituximab,” he said.
The study is sponsored by the Lymphoma Academic Research Organisation. The investigators reported relationships with Roche, Janssen-Cilag, Gilead, Servier, and Novartis.
SOURCE: Le Gouill S et al. EHA Congress, Abstract S103.