CHICAGO—Polatuzumab vedotin, when added to bendamustine (B) and rituximab (R), significantly improved response and survival rates in a cohort of patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), according to a phase 2 study.
By contrast, there were no such improvements in a cohort of follicular lymphoma (FL) patients, at least in short-term follow-up, investigator Laurie Helen Sehn, MD, of the BC Cancer Agency in Vancouver, Canada, said at the 2018 ASCO Annual Meeting.
However, the improvement in overall survival in DLBCL patients is “remarkable,” Dr Sehn affirmed in an oral presentation (abstract 7507).
“Based on these encouraging results, polatuzumab vedotin has received breakthrough therapy designation and priority medicines designation by the FDA and EMA for patients with relapsed or refractory DLBCL,” she said.
Polatuzumab-BR study (NCT02257567)
The study by Dr Sehn and colleagues included a cohort of 80 DLBCL patients randomized to BR or polatuzumab-BR for 6 planned 21-day cycles.
Investigators randomized another cohort of 80 FL patients to BR or polatuzumab-BR for 6 planned 28-day cycles.
The primary endpoint was complete response (CR) assessed by fluorodeoxyglucose positron emission tomography (FDG-PET) at 6 to 8 weeks after the end of treatment.
A total of 40% of polatuzumab-BR-treated DLBCL patients achieved CR at the end of treatment, versus 15% of BR-treated patients (P=0.012).
That CR improvement translated into a significantly higher progression-free survival (PFS) (6.7 months for polatuzumab-BR vs 2.0 months for BR, P<0.0001) and overall survival (11.8 months versus 4.7 months, P=0.0008), according to Dr Sehn.
The FDG-PET CR rates were higher in the polatuzumab-BR arm regardless of the number of prior lines of treatment for DLBCL, and regardless of relapsed versus refractory status, Dr. Sehn added.
By contrast, in the FL cohort, the FDG-PET CR rate was high for both arms, at 69% for polatuzumab-BR and 63% for BR.
And there was no significant difference in progression-free survival (P=0.58) with “relatively short-term follow-up,” she said.
The most common grades 3 – 5 adverse events for both DLBCL and FL patients were higher in the polatuzumab-BR arm than the BR arm and included cytopenias, febrile neutropenia, and infections.
Serious AEs were also higher in the polatuzumab-BR arm and included febrile neutropenia for both FL and DLBCL patients and infection for FL patients.
Five percent of FL patients and 18% of DLBCL had a grade 5 event.
Whether polatuzumab vedotin will change treatment paradigms for DLBCL patients may be answered by the ongoing POLARIX study, according to Alison Moskowitz, MD, of Memorial Sloan Kettering Cancer Center in New York, NY.
The randomized phase 3 POLARIX study (abstract TPS7589) is comparing polatuzumab plus R-CHP to R-CHOP in patients with previously untreated DLBCL.
“Certainly, there are patients who do very well with R-CHOP chemotherapy alone, and so we need to learn whether this is necessary for all patients, or only the high-risk patients,” Dr Moskowitz said in a talk at ASCO commenting on the results of the polatuzumab-BR study.
Hoffman-LaRoche is the sponsor of the study.