CD20-Targeted α-Radionuclides Synergize with Immune Checkpoint Inhibition to Treat Murine Lymphoma

Area of Science:

• Oncology
• Immunology
• Radiotherapy

Background:

• Treatment-refractory and relapsed lymphomas are leading causes of patient mortality.
• Alpha-particle radiation therapy is suitable for targeting microcluster disease and can stimulate antitumor immune effects.
• Immune checkpoint inhibition is a potential combination treatment, especially when therapeutic targets are lost.

Purpose of the Study:

• To evaluate the therapeutic efficacy of combining alpha-particle radiotherapy (using 211At-labeled antihuman CD20 monoclonal antibodies) with immune checkpoint inhibition.
• To assess this combination in a preclinical model of aggressive lymphoma.

Main Methods:

• Human CD20 transgenic mice with murine lymphomas (hCD20(+) and hCD20(-)) on opposing flanks were used.
• Therapeutic efficacy was evaluated using 211At-labeled antihuman CD20 monoclonal antibodies combined with immune checkpoint inhibitors (PD1, CTLA4, CD47, TIM3).

Main Results:

• Immune checkpoint inhibitors alone or in doublets showed no efficacy.
• 211At-hCD20 alone suppressed tumor growth in a dose-dependent manner.
• Combining low-dose 211At-hCD20 with PD1 or PD1 plus CTLA4 significantly enhanced tumor suppression and increased mouse survival.

Conclusions:

• The synergistic combination of alpha-radiotherapy and immune checkpoint inhibition shows promise for treating high-risk aggressive lymphomas.
• This approach may benefit patients with minimal residual disease or antigen loss after targeted therapies.