The novel bispecific antibody odronextamab (REGN1979) is demonstrating encouraging activity, durable responses, and acceptable safety in a phase 1 study of patients with highly refractory B-cell non-Hodgkin lymphoma, according to an investigator.
Durable complete responses (CRs) to odronextamab are being observed in more than 80% of heavily pretreated patients with follicular lymphoma (FL) in the ongoing study, said Rajat Bannerji, MD, PhD, of Rutgers Cancer Institute of New Jersey, New Brunswick.
Likewise, durable CRs were seen in greater than 80% of patients diffuse large B-cell lymphoma (DLBCL) not previously exposed to chimeric antigen receptor (CAR) T-cell therapy, and also in about 20% of patients who were treated with CAR T cells, Dr. Bannerji reported at the annual meeting of the American Society of Hematology, held virtually this year.
For these patients with FL or DLBCL in the phase 1 study, cytokine release syndrome (CRS) and neurotoxicity events did not exceed grade 3 in severity, and no cases of tumor lysis syndrome (TLS) were observed, Dr. Bannerji added in his presentation.
Those findings suggest odronextamab, which binds to CD3 on T cells and CD20 on malignant B cells, may offer an “off-the-shelf, primarily outpatient treatment option” for patients with relapsed or refractory B-cell NHL, he said in concluding remarks on the study.
This first-in-human study took a conservative approach, according to Dr. Bannerji, by mandating hospital admission during an initial step-up dosing schedule used along with dexamethasone to mitigate risk of CRS.
“With our step-up dosing and steroid premedication, we really have not seen too many cytokine release issues, and I do think that in the future it would be safe even to do step-up in the majority of patients as an outpatient,” he said in a discussion following his presentation.
Durability with further follow-up
Phase 1 data for odronextamab reported by Dr. Bannerji at the 2019 ASH meeting showed encouraging safety, tolerability, and preliminary efficacy in patients with relapsed or refractory B-cell NHL at doses up to 320 mg weekly.
In the presentation at this year’s ASH meeting, Dr. Bannerji provided updated safety and efficacy results, including longer follow-up for duration of response.
In patients with relapsed/refractory FL, the overall response rate (ORR) was 90% (27 of 30 patients), including a CR rate of 70% (21 of 30 patients), it was reported at ASH 2020. The median duration of complete response (DoCR) was not reached, with 81% of CRs durable and ongoing for up to 41 months, according to Dr. Bannerji.
In patients with relapsed/refractory DLBCL who had not received prior CAR T-cell therapy, the ORR was 55% (6 of 11 patients), all of which were complete responses, data show. The median DoCR was again not reached, with 83% of CRs durable and ongoing for up to 21 months as of this report.
In a larger group of patients with relapsed/refractory DLBCL who had received CAR T-cell therapy, the ORR was 33% (8 of 24 patients) including a 21% CR rate (5 of 24 patients). Median DoCR was not reached, the study data show, with 100% of these CRs ongoing for up to 20 months.
Odronextamab was given up to 320 mg weekly with no dose-limiting toxicities and the maximum tolerated dose not reached, according to Dr. Bannerji, who noted that no patients had discontinued treatment because of CRS or neurotoxicity.
Cytokine release syndrome was seen in about 35% of patients with DLBCL, FL, or other B-cell NHLs (48 of 136 patients), and most cases were grade 1 or 2 in severity. No FL or DLBCL patients experienced CRS higher than grade 3, according to the investigator, who reported one case of grade 3 CRS occurring out of 38 FL patients (about 3%) and four cases of grade 3 CRS out of 78 total DLBCL patients (about 5%).
No patients with FL experienced immune effector cell-associated neurotoxicity syndrome (ICANS)-like events of grade 3 or greater, the investigator said. Three cases of grade 3 ICANS-like events were reported among DLBCL patients: two cases that occurred during the step-up dosing phase and one that occurred at full dose.
No TLS events of grade 3 or greater were observed in any FL or DLBCL patients, he added.