Tumor Cells Surviving Exposure to Proton or Photon Radiation Share a Common Immunogenic Modulation Signature, Rendering Them More Sensitive to T Cell–Mediated Killing

Abstract

Purpose This study was designed to provide the foundation for combining immunotherapy to induce tumor antigen-specific T cells with proton radiation therapy to exploit the activity of those T cells. We have recently defined “immunogenic modulation,” a mechanism distinct from immunogenic cell death, whereby tumor cells surviving photon radiation therapy nonetheless become more susceptible to cytotoxic T lymphocyte (CTL)-mediated lysis. However, to our knowledge, there are no prior studies examining the role of proton radiation on tumor immune sensitivity. Materials and Methods Using cell lines of tumors frequently treated with proton radiation, such as prostate, breast, lung, and chordoma, we examined the effect of proton radiation on the viability and induction of immunogenic modulation in tumor cells by flow cytometric and immunofluorescent analysis of surface phenotype and the functional immune consequences. Results These studies show for the first time that a) proton and photon radiation induced comparable upregulation of surface molecules involved in immune recognition (HLA, ICAM-1, and the tumor-associated antigens CEA and MUC-1), b) proton radiation mediated calreticulin cell-surface expression, increasing sensitivity to cytotoxic T-lymphocyte killing of tumor cells, and c) cancer stem cells (CSCs), which are resistant to the direct cytolytic activity of proton radiation, nonetheless upregulated calreticulin after radiation in a manner similar to non-CSCs. Conclusions These findings offer a rationale for the use of proton radiation in combination with immunotherapy, including for patients who have failed radiation therapy alone or have limited treatment options.

Enhanced killing of chordoma cells by antibody-dependent cell-mediated cytotoxicity employing the novel anti-PD-L1 antibody avelumab

“…This increased PD-L1 expression significantly increased the chordoma cells' sensitivity to avelumab-mediated ADCC of NK cells (Figure 3D). In a previous study we observed that radiation did not modulate PD-L1 expression on tumor cell lines [44]. Similarly, chordoma cell lines (JHC7, UM-Chor1, U-CH2, and MUG-Chor1) exposed to 8 Gy radiation showed no increase in PD-L1 expression after 72 h (Supplemental Table 1).…”

A Pilot Study of Stereotactic Body Radiation Therapy Combined with Cytoreductive Nephrectomy for Metastatic Renal Cell Carcinoma

“…3) is supported by published in vitro studies showing an upregulation of these tumor-associated antigens in multiple non renal cell carcinoma cell lines following ionizing radiation (13, 37). Similarly, the tumor-associated antigen CA9 was found to be elevated following SBRT in our study (Fig.…”

“…A growing body of evidence has also demonstrated that sublethal doses of radiation can induce expression of calreticulin and CD80, leading to increased cytotoxic lymphocyte activity following irradiation of tumor cells (12–14). Preclinical tumor models and in vitro data utilizing other tumor types have revealed that radiation therapy can increase TAA expression (13, 15). While RCC appears resistant to conventional fractionated radiation therapy (16), recent publications have shown that high doses delivered with modern stereotactic body radiation therapy (SBRT) can produce local control with limited toxicity (17, 18).…”

A Proteomic Analysis of the Malignant Mesothelioma Secretome Using iTRAQ

“…Subsets of patients with various cancers with low CALR expression responded less well to inducers of immunogenic cell death than patients with high CALR expressing tumours (65). Cells from a variety of cancers that have survived exposure to radiation express more cell surface CALR and this was associated with an enhanced sensitivity to cytotoxic T-cell killing (66). CD166 antigen (ALCAM), that was consistently up-regulated in this study, is an immunoglobulin receptor that binds to the CD6 T-cell differentiation antigen.…”