Recent studies in cancer research have focused intensely on the antineoplastic effects of immune checkpoint inhibitors. While the development of these inhibitors has progressed successfully, strategies to further improve their efficacy and reduce their toxicity are still needed. We hypothesized that the delivery of anti–PD-1 antibody encapsulated in PLGA nanoparticles (anti–PD-1 NPs) to the spleen would improve the antitumor effect of this agent. Unexpectedly, we found that mice treated with a high dose of anti–PD-1 NPs exhibited significantly higher mortality compared with those treated with free anti–PD-1 antibody, due to the overactivation of T cells. Administration of anti–PD-1 NPs to splenectomized LT-α–/– mice, which lack both lymph nodes and spleen, resulted in a complete reversal of this increased mortality and revealed the importance of secondary lymphoid tissues in mediating anti–PD-1–associated toxicity. Attenuation of the anti–PD-1 NPs dosage prevented toxicity and significantly improved its antitumor effect in the B16-F10 murine melanoma model. Furthermore, we found that anti–PD-1 NPs undergo internalization by DCs in the spleen, leading to their maturation and the subsequent activation of T cells. Our findings provide important clues that can lead to the development of strategies to enhance the efficacy of immune checkpoint inhibitors.
Farideh Ordikhani, Mayuko Uehara, Vivek Kasinath, Li Dai, Siawosh K. Eskandari, Baharak Bahmani, Merve Yonar, Jamil R. Azzi, Yousef Haik, Peter T. Sage, George F. Murphy, Nasim Annabi, Tobias Schatton, Indira Guleria, Reza Abdi
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. We reserve the right to edit any letter for length, content, and clarity. Authors will be notified by e-mail if their letters were accepted. No appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.