A phase I/II trial for the experimental drug mosunetuzumab met its primary endpoint, leading to deep, durable remissions for patients with relapsed or refractory follicular lymphoma.

In the single-arm study, presented at ASH 2021, 80% of patients responded to the treatment and 60% experienced a complete response.

“This is a very efficacious, very safe drug, even for subgroups of patients who typically do not respond well to existing therapies,” said L. Elizabeth Budde, MD, PhD, of City of Hope Comprehensive Cancer Center in California. “The results are a strong endorsement of the unique mechanism of action for this drug.”

Mosunetuzumab is a type of bispecific antibody designed to recognize a target on the lymphoma cells and a target on the patient’s own immune T cells and bring the two together.

“It acts as a bridge to give a patient’s T cells guidance to help them get in the proximity of the lymphoma cell, become active, and destroy the lymphoma cell,” said Dr. Budde.

Unlike CAR T-cell therapy, which also uses T cells to fight cancer, mosunetuzumab can be infused directly into the bloodstream without requiring the removal and modification of patients’ immune cells.

The trial enrolled 90 patients who had seen their follicular lymphoma return after two or more rounds of treatment with existing therapies.

Patients were infused with mosunetuzumab and followed for a median of more than 18 months.

More than 60% of those who responded to the treatment and 76% of those who achieved a complete response experienced no complications or cancer progression a year after treatment.

Similar to CAR T-cell treatment, the trial also saw cytokine release syndrome (CRS), which occurred in 44.4% of patients.

All but two instances of CRS were low-grade, and all CRS events were manageable and reversible.

CRS is an inflammatory response common in immune-modulating therapies.

Overall, the therapy was well tolerated and the participants, including older patients, did not require hospitalization.

Many participants were able to continue their normal daily routines throughout treatment, researchers said.

“The goal is not only to treat the lymphoma but to improve the quality of life for patients,” said Dr. Budde. “By motivating our immune system to recognize lymphoma cells, this drug could give us an opportunity for chemotherapy-free treatment for follicular lymphoma.”

See the video interview of Prof Budde here.

Source: American Society of Haematology (ASH)