Shee Eun Lee1, Seol Hee Hong1, Hye Hwa Lee1, Kwangjoon Jeong1, Tan Wenzhi1, Mee Sun Yoon2, In-Kyu Park1, Jung-Joon Min1, Joon Haeng Rhee1
1Clinical Vaccine R&D Center, Chonnam National University, Gwangju, Republic of Korea;
2Department of Radiation Oncology, Chonnam National University Hwasun Hospital, Chonnam National University Medical School, Gwangju, Republic of Korea
Accumulating evidence demonstrates that radiotherapy enhances anti-tumor immune responses induced by immunomodulatory therapeutic approaches. Radiotherapy (RT) is widely used cost-effective therapeutics for the various cancers having accompanying adverse effect. Recently it has been reported that flagellin derivatives significantly reduced the severity of radiation-induced side effect and accelerated tissue recovery. We previously demonstrated that flagellin potentiates tumor antigen-specific CD8⁺ T cell immune responses through TLR5 signaling in a TC-1 cancer immunotherapy (IT) model. And intravaginal (IVAG) co-administration of E6/E7 peptides with flagellin resulted in tumor suppression indicating flagellin is a potent vaginal adjuvant for a therapeutic peptide cancer vaccine. In this regard, we examined whether flagellin can be used as an adjuvant performing dual role of radioprotection and immunomodulation in an RT/IT combinatorial cervical cancer therapeutic model. When the tumor-bearing mice (5 ~8 mm in mean diameter) were locally received 20 Gy single dose irradiation, tumor growth was significantly reduced. Additional administration of flagellin-adjuvanted peptide vaccine showed comparable inhibitory effect on tumor growth. Surprisingly the combination therapy of flagellin-adjuvanted cancer vaccine and radiotherapy induced eradication of tumor mass and long-term memory protection against the re-challenge of the same tumor. These results suggest that flagellin is a promising radioprotective adjuvant for RT/IT combination therapeutics modalities against intractable cancers.
Credits: None available.
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