7 Analytical comparison of a PD-L1 22C3 antibody laboratory-developed test protocol on the Benchmark XT and PD-L1 IHC 22C3 pharmDx: pan-tumor and triple-negative breast cancer samples

Background

PD-L1 IHC 22C3 pharmDx is an FDA-approved companion diagnostic for pembrolizumab across multiple tumor types designed for use on the Autostainer Link 48 (AL48). Many pathology laboratories do not have access to the AL48 and therefore do not use PD-L1 IHC 22C3 pharmDx but instead assess PD-L1 using laboratory-developed tests (LDTs) on the Ventana BenchMark platform. We compared our PD-L1 22C3 antibody-based LDT on the BenchMark XT platform with PD-L1 IHC 22C3 pharmDx using cervical cancer (CC), head and neck squamous cell carcinoma (HNSCC), urothelial carcinoma (UC), esophageal SCC (ESCC), and triple-negative breast cancer (TNBC) samples.

Methods

Tumor specimens from patients with CC, HNSCC, UC, ESCC, and TNBC were stained with the 22C3 antibody, scored using the LDT on the BenchMark XT as previously described,1 and compared with PD-L1 IHC 22C3 pharmDx scored by a trained pathologist, who measured PD-L1 with the use of combined positive score (CPS) and standard cutoffs (HNSCC and CC, ≥1; UC, ESCC, and TNBC, ≥10). Agreement in PD-L1 CPS as determined using the LDT and the PD-L1 IHC 22C3 pharmDx was evaluated.

Results

423 samples with CC (n = 77), HNSCC (n = 126), UC (n = 121), ESCC (n = 80), and TNBC (n = 19) were evaluated in this study. The pan-tumor (CC, HNSCC, UC, and ESCC) intraclass correlation coefficient (ICC) of PD-L1 CPS as a continuous variable was 0.95 (95% CI, 0.94%–0.96%); Spearman correlations were 0.95. ICC (95% CI) was 0.92 (0.88–0.95) for CC, 0.97 (0.96–0.98) for HNSCC, 0.95 (0.92–0.97) for UC, and 0.92 (0.88–0.95) for ESCC; Spearman correlation was 0.93, 0.96, 0.92, and 0.89, respectively. The overall percentage agreement at the respective CPS cutoff was 96% (CC), 96% (HNSCC), 96% (UC), and 90% (ESCC). Staining patterns by 22C3 LDT and PD-L1 IHC 22C3 pharmDx were also very similar in our TNBC pilot study; however, correlation was not calculated because of the small sample numbers.

Conclusions

The PD-L1 22C3 antibody-based LDT on the BenchMark XT demonstrated high concordance with PD-L1 IHC 22C3 pharmDx. These findings suggest the comparability of PD-L1 IHC 22C3 pharmDx with an LDT based on the 22C3 antibody across several tumor types. Further validation for TNBC is ongoing to confirm the data from the pilot run.

Reference

Neuman T, et al. J Thorac Oncol. 2016;11:1863–1868.

Abstract 503: Analytical comparison of a PD-L1 22C3 antibody LDT protocol on the BenchMark XT and PD-L1 IHC 22C3 pharmDx: Analysis of pan-tumor and esophageal cancer samples

Background: PD-L1 IHC 22C3 pharmDx is an FDA-approved companion diagnostic to pembrolizumab across multiple tumor types designed for use on the Autostainer Link 48 (AL48). Many pathology laboratories do not have access to the AL48 and therefore do not use PD-L1 IHC 22C3 pharmDx to assess PD-L1 status. As a result, these laboratories often assess PD-L1 using laboratory-developed tests (LDTs) on the Ventana BenchMark platform. We compared our PD-L1 22C3 antibody-based LDT on the BenchMark XT platform with PD-L1 IHC 22C3 pharmDx. Data using head and neck squamous cell carcinoma (HNSCC) and urothelial carcinoma (UC) samples alone have previously been presented (Vainer GW et al. 31st European Congress of Pathology; September 7-11, 2019). In the current study, we performed a pan-tumor analysis that also included samples from patients with esophageal SCC (ESCC).

Methods: The LDT used for this analysis has been described (Neuman T et al. J Thorac Oncol. 2016;11:1863-1868). Tumor specimens from patients with HNSCC, UC, and ESCC were stained with the 22C3 antibody, scored using the LDT on the BenchMark XT platform, and compared with PD-L1 IHC 22C3 pharmDx by one trained pathologist. PD-L1 was measured using the combined positive score (CPS) by the pathologist using standard cutoffs (HNSCC, ≥1; UC and ESCC, ≥10). After PD-L1 status was determined using the LDT and PD-L1 IHC 22C3 pharmDx, the agreement between both assays was measured.

Results: Samples from 327 patients with HNSCC (n = 126), UC (n = 121), and ESCC (n = 80) were evaluated for this study. The pan-tumor intraclass correlation coefficient (ICC) of PD-L1 CPS as a continuous variable was 0.96 (95% CI, 0.95-0.97); Spearman correlation was 0.95. Among patients with ESCC, ICC was 0.92 (95% CI, 0.88-0.95) and Spearman correlation was 0.89. The clinical interpretation of PD-L1 status (CPS ≥10) for ESCC samples using the 22C3 antibody LDT on the BenchMark XT platform and PD-L1 IHC 22C3 pharmDx resulted in a negative percentage agreement of 92% (95% CI, 80-97), a positive percentage agreement of 88% (95% CI, 74-95), and an overall percentage agreement of 90% (95% CI, 81-95).

Conclusions: The 22C3 antibody-based LDT on the BenchMark XT platform demonstrated high concordance with the FDA-approved PD-L1 IHC 22C3 pharmDx across tumor types and in patients with ESCC alone. These findings suggest the comparability of PD-L1 IHC 22C3 pharmDx with an LDT based on the 22C3 antibody across several tumor types. This analysis will be expanded to include additional indications for inclusion in the presentation.

Citation Format: Gilad W. Vainer, Ghadeer Zatara, Lingkang Huang, Kenneth Emancipator, Shanthy Nuti. Analytical comparison of a PD-L1 22C3 antibody LDT protocol on the BenchMark XT and PD-L1 IHC 22C3 pharmDx: Analysis of pan-tumor and esophageal cancer samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 503.

Novel Proteome Extraction Method Illustrates a Conserved Immunological Signature of MSI-H Colorectal Tumors

Using a simple, environment friendly proteome extraction (TOP), we were able to optimize the analysis of clinical samples. Using our TOP method we analyzed a clinical cohort of microsatellite stable (MSS) and unstable (MSI-H) colorectal carcinoma (CRC). We identified a tumor cell specific, STAT1-centered, immune signature expressed by the MSI-H tumor cells. We then showed that long, but not short, exposure to Interferon-γ induces a similar signature in vitro We identified 10 different temporal protein expression patterns, classifying the Interferon-γ protein temporal regulation in CRC. Our data sheds light on the changes that tumor cells undergo under long-term immunological pressure in vivo, the importance of STAT proteins in specific biological scenarios. The data generated could help find novel clinical biomarkers and therapeutic approaches.

Suppression of FoxO1 activity by long-chain fatty acyl analogs

OBJECTIVE

Overactivity of the Forkhead transcription factor FoxO1 promotes diabetic hyperglycemia, dyslipidemia, and acute-phase response, whereas suppression of FoxO1 activity by insulin may alleviate diabetes. The reported efficacy of long-chain fatty acyl (LCFA) analogs of the MEDICA series in activating AMP-activated protein kinase (AMPK) and in treating animal models of diabesity may indicate suppression of FoxO1 activity.

RESEARCH DESIGN AND METHODS

The insulin-sensitizing and anti-inflammatory efficacy of a MEDICA analog has been verified in guinea pig and in human C-reactive protein (hCRP) transgenic mice, respectively. Suppression of FoxO1 transcriptional activity has been verified in the context of FoxO1- and STAT3-responsive genes and compared with suppression of FoxO1 activity by insulin and metformin.

RESULTS

Treatment with MEDICA analog resulted in total body sensitization to insulin, suppression of lipopolysaccharide-induced hCRP and interleukin-6-induced acute phase reactants and robust decrease in FoxO1 transcriptional activity and in coactivation of STAT3. Suppression of FoxO1 activity was accounted for by its nuclear export by MEDICA-activated AMPK, complemented by inhibition of nuclear FoxO1 transcriptional activity by MEDICA-induced C/EBPβ isoforms. Similarly, insulin treatment resulted in nuclear exclusion of FoxO1 and further suppression of its nuclear activity by insulin-induced C/EBPβ isoforms. In contrast, FoxO1 suppression by metformin was essentially accounted for by its nuclear export by metformin-activated AMPK.

CONCLUSIONS

Suppression of FoxO1 activity by MEDICA analogs may partly account for their antidiabetic anti-inflammatory efficacy. FoxO1 suppression by LCFA analogs may provide a molecular rational for the beneficial efficacy of carbohydrate-restricted ketogenic diets in treating diabetes.