Loss of PD-L1 (SP-142) expression characterizes renal vein tumor thrombus microenvironment in clear cell renal cell carcinoma

Immunotherapy is a promising tool in the treatment of patients with advancer renal cancer, in particular the blockage of immune checkpoint inhibitors. Clear cell renal cell carcinoma is an example of heterogeneous neoplasm and this particular characteristic is responsible of many therapeutic failures so far. Since variations in the local microenvironment across a tumor may conditionate the effect of this new therapy, a deeper knowledge of this issue seems advisable for any treatment success. We have analyzed the PD-L1 (SP142) expression in three different areas in the tumor and in two areas in the renal vein/caval thrombi in 39 advanced clear cell renal cell carcinomas to determine the extent and potential clinical significance of this regional variability. A statistically significant decrease in PD-L1 expression has been detected between the main tumor and its thrombus faction (p < 0.0001). Also, we have observed a high variability in the PD-L1 positivity across the three different areas of the main tumor tested, with only three cases being uniformly positive in all tested areas. In conclusion, PD-L1 expression display a highly variable distribution in clear cell renal cell carcinomas and this particularity should be kept in mind when selecting the tumor samples to be tested for immunotherapy.

A multi-site cutting device implements efficiently the divide-and-conquer strategy in tumor sampling

We recently showed that in order to detect intra-tumor heterogeneity a Divide-and-Conquer (DAC) strategy of tumor sampling outperforms current routine protocols. This paper is a continuation of this work, but here we focus on DAC implementation in the Pathology Laboratory. In particular, we describe a new simple method that makes use of a cutting grid device and is applied to clear cell renal cell carcinomas for DAC implementation. This method assures a thorough sampling of large surgical specimens, facilitates the demonstration of intratumor heterogeneity, and saves time to pathologists in the daily practice. The method involves the following steps: 1. Thin slicing of the tumor (by hand or machine), 2. Application of a cutting grid to the slices ( e.g., a French fry cutter), resulting in multiple tissue cubes with fixed position within the slice, 3. Selection of tissue cubes for analysis, and finally, 4. Inclusion of selected cubes into a cassette for histological processing (with about eight tissue fragments within each cassette). Thus, using our approach in a 10 cm in-diameter-tumor we generate 80 tumor tissue fragments placed in 10 cassettes and, notably, in a tenth of time. Eighty samples obtained across all the regions of the tumor will assure a much higher performance in detecting intratumor heterogeneity, as proved recently with synthetic data.

A multi-site cutting device implements efficiently the divide-and-conquer strategy in tumor sampling

We recently showed that in order to detect intra-tumor heterogeneity a Divide-and-Conquer (DAC) strategy of tumor sampling outperforms current routine protocols. This paper is a continuation of this work, but here we focus on DAC implementation in the Pathology Laboratory. In particular, we describe a new simple method that makes use of a cutting grid device and is applied to clear cell renal cell carcinomas for DAC implementation. This method assures a thorough sampling of large surgical specimens, facilitates the demonstration of intratumor heterogeneity, and saves time to pathologists in the daily practice. The method involves the following steps: 1. Thin slicing of the tumor (by hand or machine), 2. Application of a cutting grid to the slices ( e.g., a French fry cutter), resulting in multiple tissue cubes with fixed position within the slice, 3. Selection of tissue cubes for analysis, and finally, 4. Inclusion of selected cubes into a cassette for histological processing (with about eight tissue fragments within each cassette). Thus, using our approach in a 10 cm in-diameter-tumor we generate 80 tumor tissue fragments placed in 10 cassettes and, notably, in a tenth of time. Eighty samples obtained across all the regions of the tumor will assure a much higher performance in detecting intratumor heterogeneity, as proved recently with synthetic data.