Feasibility of multiple immunoexpression assay for immune tumor micrornvironment (I-TME) on matched metastatic and primary renal cell carcinoma (RCC) for patient prognostication and predictiveness to immunotherapy (preliminary analyses of the Meet URO 18 study).
Authors: Matteo Brunelli, Sara Elena Rebuzzi, Valerio Gaetano Vellone, Marta Sbaraglia, Gabriele Gaggero, Matteo Fassan, Marco Maruzzo, Umberto Basso, Melissa Bersanelli, Alessandra Damassi, Valentino Martelli, Fabio Catalano, Francesco Pierantoni, Chiara Casartelli, Sara Merler, Gianluca Businello, Michele Milella, Sebastiano Buti, Giuseppe Fornarini
Journal: Journal of Clinical Oncology (2021)

e16545 Background: The Meet-URO 18 study is ongoing to assess the prognostic role of I-TME in advanced RCC patients treated with ≥second line nivolumab divided into two cohorts according to clinical benefit [progression-free survival ≥ 12 and ≤ 3 months]. We primarily assessed the feasibility of multiple antibody testing related to I-TME on matched metastases and primary tumor. Methods: Immunohistochemical analyses were used for the TME assessment of T-lineage (CD3, CD4, CD8), FOXP-3, granulocytes (CD15), macrophage-lineage (CD68), natural killer (NK)-cells (CD56), tumor cells (TCs) (CD56), B-lineage (CD20) and phosphorylated mTOR (phmTOR). TCs were quantitatively assessed for CD15, CD56 and phmTOR positivity. For T-, B- and CD68 cells within TC nests, the number of immunoreactive cells were counted with a microscopic field of x200 (0.933 mm 2 ). Results: Overall, 42 tumor tissue samples (primary tumors, metastases) were available and for 17 patients both metastatic and primary tumor tissues were assessable for matched analyses. Among these patients, 12 had clear cell, 1 papillary and 4 mucinous tubular and spindle cell histotype according to WHO 2016 classification. Intratumoral T/CD8 cells ranged from 32 to &gt;400 spots (mean 240; &gt;400 in 7 samples) and intratumoral T/CD4 cells from 4 to &gt;400 spots (mean 168; &gt;400 in 5 samples). Nine samples showed absence of phmTOR expression, while 8 ranged from 10% to 90% of positive TCs. We did not observe countable NK-cells, whereas CD56 was visible in 5 samples (mean 55% of positive TCs). Intratumoral CD68 cells ranged from 34 to &gt;400 spots (mean 175, &gt;400 in 3 patients). Agreement of CD15 method of reporting granulocytic presence was high, thus only CD15 neoplastic expression was reported and ranged from 12% to 55% (mean 30%) in 15 patients. TME multiple analysis resulted equally clustered in 8 patients (&lt;20% variability of single immuno-test) whereas the remaining 9 patients showed significant differences as percentage of immuno-tissue expression in at least one of the 5 immuno-indicators (T/CD8-CD4, C15, CD68, CD56, phmTOR). The remaining 8 samples of patients without matched analyses were used to test the feasibility of multiple analyses; among all antibodies exclusion of the CD20 and FOXP-3 final evaluation was needed, due to technical standardization. According to the 5 immuno-indicators, double-triple positive or penta-positive TME indicators may be identified and graded. Conclusions: Providing multiple immunoexpression platforms on a single specimen may be used as routine workflow. Profiling I-TME, especially CD56, CD15 on TCs and CD68 cells and phmTOR, deserves investigation with extensive control groups. A validation cohort will be tested at tissue level and in correlation with peripheral blood markers.