Biomarker List

Overview StrataEXPTM is an analytically and clinically validated multi-gene expression test that uses RNA sequencing to report the expression of 10 biomarkers, which are targeted by multiple approved and investigational therapies, including antibodies, antibody drug conjugates, radiopharmaceuticals and immunotherapies. StrataEXP is performed in parallel to StrataNGS testing from the same isolated RNA and results are provided as supplemental information. The following table summarizes the biomarkers included in StrataEXP, associated therapies and the rationale for inclusion.

Target Associated Therapies Rationale Statement ERBB2 trastuzumab, Several antibodies, small molecule inhibitors, bispecific antibodies, and antibody (Her2) pertuzumab, tucatinib, drug conjugates targeting HER2 have been approved for HER2 3+ by IHC in breast neratinib, trastuzumab and other tumor types. The gene expression threshold for HER2 was set at 13.2, deruxtecan, which associated with 100% sensitivity and 85.5% specificity for 3+ expression by margetuximab, HER2 IHC in a cohort of 253 Strata-tested breast cancer samples. trastuzumab emtansine CD274 pembrolizumab, Several antibodies targeting PD-L1 (and/or PD-1) have been approved in multiple (PD-L1) atezolizumab, tumor types, with PD-L1 expression by IHC predicting benefit in some tumor types by nivolumab+ipilimumab, a variety of scoring systems. The gene expression threshold for PD-L1 was set at 11.3, nivolumab, durvalumab, which associated with 82% sensitivity and 82% specificity for PD-L1 expression by cemiplimab TPS >50% (22C3 clone) in a cohort of 136 Strata-tested NSCLC tumor samples. AR ADT+bicalutamide, Multiple hormonal androgen deprivation therapies (ADT) and small molecule AR (Androgen enzalutamide, inhibitors (e.g. bicalutamide, enzalutamide, apalutamide and darolutamide) are receptor) apalutamide, approved for treating patients with metastatic prostate cancer. ADT + bicalutamide darolutamide are recommended by the NCCN for salivary gland carcinoma expressing AR by IHC. Although recent evidence suggests AR may act as a tumor suppressor in ER+ breast cancer (PMID: 33462444), enzalutamide showed an 8% objective response rate (and 22% rate of at least stable disease at 24 weeks) in patients with triple negative breast cancer expressing >10% AR by IHC (PMID: 29373071). The gene expression threshold for AR was set at 14.4, which corresponds to the top 80% of AR expression in Strata-tested salivary gland carcinoma samples. PVRL4 enfortumab vedotin Enfortumab vedotin, an antibody drug conjugate targeting Nectin-4, is approved for (Nectin-4) treating patients with metastatic urothelial (bladder) carcinoma, where it showed a 41% and 52% objective response rates in the 3rd and 2nd line, respectively (PMID: 33577729; GU ASCO 2021). The gene expression threshold for Nectin-4 was set at 12.5, which corresponds to the top 45% of Nectin-4 expression in Strata-tested bladder cancer samples. TACSTD2 sacituzumab govitecan Sacituzumab govitecan, an antibody drug conjugate targeting TROP2, is approved (TROP2) for treating patients with triple negative breast cancer, where it demonstrated a 33% objective response rate (ORR; PMID: 30786188). In a phase II study in patients with 3rd line bladder cancer, sacituzumab govitecan showed a 27% ORR (ESMO 2020). The gene expression threshold for TROP2 was set at 12.5, which corresponds to the top 36% of TROP2 expression in Strata-tested bladder cancer samples.

StrataEXP is provided as supplemental information. Target Associated Therapies Rationale Statement SLC39A6 ladiratuzumab vedotin Ladiratuzumab vedotin, an investigational antibody drug conjugate targeting LIV-1, (LIV-1)* demonstrated a 32% objective response rate in unselected patients with 3rd line triple negative breast cancer (PMID: 32426047). The gene expression threshold for LIV-1 was set at 11.6, which corresponds to the top 25% of LIV-1 expression in Strata- tested triple negative breast cancer samples. SLC34A2 XMT-1536 XMT-1536, an investigational antibody drug conjugate targeting NaPi2b, (NaPi2b)* demonstrated a 32% objective response rate in patients with heavily pre-treated ovarian cancer and high NaPi2b expression by IHC (Mersana; JPM 2021). The gene expression threshold for NaPi2b was set at 17.5, which corresponds to the top 35% of NaPi2b expression in Strata-tested ovarian cancer samples. FOLR1 STRO-002, STRO-002, an investigational antibody drug conjugate targeting FOLR1, (Folate mirvetuximab demonstrated a 32% objective response rate in unselected patients with heavily pre- receptor)* soravtansine treated ovarian cancer (Sutro Biopharma; JPM 2021). Mirvetuximab soravtansine, an investigational antibody drug conjugate targeting FOLR1, demonstrated a 31% objective response rate in a pooled cohort of patients with platinum resistant ovarian cancer and high FOLR1 expression by IHC (Immunogen JPM; 2021). The gene expression threshold for FOLR1 was set at 17.2, which corresponds to the top 25% of FOLR1 expression in Strata-tested ovarian cancer samples. FOLH1 177Lu-PSMA-617 177Lu-PSMA-617, an investigational radioligand therapy targeting PSMA, (PSMA)* demonstrated a 66% serum PSA response rate and a 49% objective response rate in PSMA-PET positive patients with post-abiraterone/enzalutamide treated castration resistant prostate cancer (PMID: 33581798). The gene expression threshold for PMSA was set at 14.0, which corresponds to the top 85% of PMSA expression in Strata-tested prostate cancer samples. Proliferation Cell proliferation, as measured by Ki67 IHC, is prognostic in many tumor types, and is the main component of many prognostic tissue-based expression tests (PMID: 16720680, PMID: 21310658). The gene expression proliferation score combines UBE2C and TOP2A, which showed a Pearson correlation coefficient of 0.82 with Ki67 proliferation index in a cohort of 250 Strata-tested tumor samples. Proliferation is reported on a scale of 7.79 to 12.1, where 7.79 represents the lowest average scoring tumor type (GIST) and 12.1 represents the highest average scoring tumor type (small cell lung cancer)

* Investigational