Dosimetric Characterization of an Abscopal Response in a Patient With Oligometastatic Melanoma Undergoing Concurrent Treatment With Pembrolizumab and Stereotactic Body Radiotherapy (SBRT).
Recently, preclinical and clinical evidence has shown that a synergy may exist between radiation and immune check-point therapies such as pembrolizumab. Radiation has been shown to activate the immune system, and in combination with immunotherapy may lead to systemic anti-tumor responses. However, the exact dose regimens needed to induce synergistic responses are unclear.
Here, we report a Dosimetric characterization of a patient treated with stereotactic radiation in combination with immune check-point therapy. Stereotactic Body Radiotherapy (SBRT) is a sophisticated form of radiation that allows high dose, conformal radiation delivery to solid tumors. In addition to providing local control, reports of Abscopal (or out-of-field) effects indicate a possible systemic effect of SBRT.
Although, clinical reports of Abscopal immune responses induced by SBRT are relatively rare, recent advances
in immunotherapy and the potential benefits of the combination of immunotherapy and SBRT have driven interest in radiation induced anti-tumor immune responses. Several clinical studies are currently underway to determine the effects of combined radiation and check-point inhibition.
Although, results of clinical trials combining PD-1 inhibition and radiation are still forthcoming,
clinical reports demonstrate that combination radio-immunotherapy may yield therapeutic advantage.4,5 While reports suggest that hypo fractionated regimens used in SBRT may induce superior immune priming, the optimal dose, and fractionation regimens are still to be determined.
Cancer Stud Mol Med Open J. 2018; 4(1): 1-4. doi: 10.17140/CSMMOJ-4-121