Benz, Christopher C.

10586 Background: Teschendorff et al. (Breast Cancer Res 2008) reported a 7-gene, immune response-enriched gene expression classifier using microarrays that was prognostic in women with ER-negative breast cancer. To facilitate further evaluation of the prognostic value of a classifier in archival fixed tumor tissue, we developed two multiplex TaqMan assays to quantify the expression levels of these genes, then trained and validated a 7-gene immune response score (IRS). Methods: RNA was extracted from FFPE sections of 185 ER-negative breast cancer patient samples from Mayo Clinic (n=81), Guy’s Hospital (n=50) and California Pacific Medical Center (CPMC) (n=27). Patients (N+ and N-) did not receive adjuvant therapy and were followed for a minimum of 5 years. Amplification of i) LY9, TNFRSF17, HLA-F, and IGLC2 and ii) XCL2, SPP1, C1QA and two reference genes NUP214 and PPIG were carried out in two multiplex RT-PCR TaqMan reactions and relative expression levels were determined using the DDCT method. The training set, comprised of the Mayo Clinic samples, was used to develop an IRS by using a summation of expression levels of the 7 genes. Association of the IRS with distant metastasis was assessed using a Cox proportional hazards model. The score was subsequently tested in a validation set (Guy’s + CPMC). Results: The amplification efficiency of each gene within the multiplex reactions was comparable to singleplex reactions. Duplicate amplifications showed excellent assay reproducibility and sensitivity (R2=0.98). The hazard ratio for a single standard deviation decrease in the IRS was 1.45 (95% CI 0.99-2.12, p=0.056) in the training set and 2.18 (1.32-3.61, p=0.002) in the validation set. ROC curves of continuous IRS to predict distant metastasis within 5 years had AUC of 0.74, 95% CI = 0.60-0.88. Conclusions: Robust multiplex TaqMan assays for FFPE tissue extracted RNA were developed for a 7-gene IRS. Increases in risk are associated with decreases in the IRS. Immune related gene expression clearly plays an important role in the spectrum of risk of ER-negative tumors. Additional signatures are in development that further support this conclusion.

AbstractThe many improvements in breast cancer therapy in recent years have so lowered rates of recurrence that it is now difficult or impossible to conduct adequately powered adjuvant clinical trials. Given the many new drugs and potential synergistic combinations, the neoadjuvant approach has been used to test benefit of drug combinations in clinical trials of primary breast cancer. A recent FDA-led meta-analysis showed that pathologic complete response (pCR) predicts disease-free survival (DFS) within patients who have specific breast cancer subtypes. This meta-analysis motivated the FDA's draft guidance for using pCR as a surrogate endpoint in accelerated drug approval. Using pCR as a registration endpoint was challenged at ASCO 2014 Annual Meeting with the presentation of ALTTO, an adjuvant trial in HER2-positive breast cancer that showed a nonsignificant reduction in DFS hazard rate for adding lapatinib, a HER-family tyrosine kinase inhibitor, to trastuzumab and chemotherapy. This conclusion seemed to be inconsistent with the results of NeoALTTO, a neoadjuvant trial that found a statistical improvement in pCR rate for the identical lapatinib-containing regimen. We address differences in the two trials that may account for discordant conclusions. However, we use the FDA meta-analysis to show that there is no discordance at all between the observed pCR difference in NeoALTTO and the observed HR in ALTTO. This underscores the importance of appropriately modeling the two endpoints when designing clinical trials. The I-SPY 2/3 neoadjuvant trials exemplify this approach. Clin Cancer Res; 21(13); 2911–5. ©2015 AACR.