Proton treatment suppresses exosome production in head and neck squamous cell carcinoma

Proton therapy can be an effective and less-toxic alternative to conventional radiation therapy for patients with advanced cancers of the head and neck, according to a study conducted by researchers at the Proton Therapy Center on the Liberty Campus of Cincinnati Children’s.

The study’s authors report that proton therapy is effective because it can be delivered with a degree of precision that spares surrounding normal tissue and therefore causes fewer side effects than X-ray based photon therapy.

“When using proton therapy, there was a significant reduction (75%) in the production of small extracellular vesicles, commonly known as exosomes, from cancer cells, which usually suppress the immune system,” the authors wrote in the study, which was published online in Cancers.

X-ray based photon therapy did not reduce exosome production, though exosomes from both proton therapy and X-ray based photon therapy had similar inhibitory effects on immune cells, according to the study, which was titled “Proton Treatment Suppresses Exosome Production in Head and Neck Squamous Cell Carcinoma.”

“Our findings suggest that proton therapy might be better at reducing the immune-suppressing effects of cancer exosomes by producing fewer of them,” the authors concluded.

Head and neck squamous cell carcinoma is the sixth-most prevalent cancer worldwide and among the most immunosuppressive, the authors stated.

“Effective cancer treatment relies on the ability of effector T and natural killer cells to infiltrate tumors and perform their effector functions,” the authors noted. “However, these immune functions are suppressed in (head and neck squamous cell carcinoma). Circulating exosomes from … patients have been shown to suppress the activities of local and peripheral effector T and (natural killer) cells.”

The researchers noted that proton and/or photon irradiation studies were conducted on primary cell cultures established from surgically resected tumors obtained from three de-identified patients treated at the University of Cincinnati Medical Center. Informed consent was obtained from the patients.

Chimote AA, Lehn MA, Bhati J, Mascia AE, Sertorio M, Lamba MA, Ionascu D, Tang AL, Langevin SM, Khodoun MV, Wise-Draper TM, Conforti L. (2024) Proton Treatment Suppresses Exosome Production in Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 16(5):1008. [article]

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