Recently, phase I studies with novel antibody drug conjugates targeting HER2 suggested benefit in HER2-low patients -defined as immunohistochemistry(IHC) +1 or +2 FISH/ISH non-amplified, with advanced breast cancer(BC). Data on the prognostic value of HER2-low in early stage disease is scarce. The purpose of this study was to evaluate the impact of HER2-low status on response to neoadjuvant chemotherapy(NACT) and survival outcomes in early stage HER2negative BC. MethodsRecords from all BC patients treated with NACT from January 2007 to December 2018 in a single cancer center were retrospectively reviewed. Primary objective was to compare differences between pathologic complete response(pCR) and relapse free survival(RFS) in luminal HER2-low/HER2-0 and triple negative(TNBC) HER2-low/HER2-0. Results855 non-HER2-positive patients were identified. Median follow-up was 59 months. 542 had luminal BC (63.4%) and 313 TNBC (36.6%). 285 (33.3%) were HER2-low. Among luminal tumors, 145 had HER2 IHC+1 (26.8%) and 91 IHC+2/ISH non-amplified (16.8%). In TNBC, only 36 had HER2 IHC+1 (11.5%) and 13 IHC+2/ISH non-amplified (4.2%). Among luminal/HER2-low and luminal/HER2-0 population, there was a high proportion of clinical T3/4 (61.5% vs 69.2%, p=0.053), node positive (74.2% vs 66.3%, p=0.27) and stage III tumors (63.1% vs 65%, p=0.51). The same was true TNBC/HER-low as compared to TNBC/HER2-0, despite a non-statistically significant higher cT4 among TNBC/HER-low (32.7% vs. 19.3%, p=0.17). pCR was 13% in luminal/HER2-low versus 9.5% in luminal/HER2-0 (p=0.27), and 51% in TNBC/HER2-low versus 47% in TNBC/HER2-0 (p=0.64). 5y RFS was 72.1% in luminal/HER2-low and 71.7% in luminal/HER2-0 (p=0.47), and 75.6% in TNBC/HER2-low versus 70.8% in TNBC/HER2-0 (p=0.23). HER2-low status was not associated with RFS in multivariate analysis (HR 0.83, 95%CI 0.6-1.11, p=0.21). ConclusionOur data does not support HER2-low as a biologically distinct BC subtype, with no predictive effect on pCR after NACT nor prognostic value on survival outcomes.

Purpose: Recently, phase I studies with novel antibody drug conjugates targeting HER2 suggested benefit in HER2-low patients – defined as immunohistochemistry(IHC) +1 or +2 FISH/ISH non-amplified, with advanced breast cancer(BC). Data on the prognostic value of HER2-low in early stage disease is scarce. The purpose of this study was to evaluate the impact of HER2-low status on response to neoadjuvant chemotherapy(NACT) and survival outcomes in early stage HER2- negative BC. Methods: Records from all BC patients treated with NACT from January 2007 to December 2018 in a single cancer center were retrospectively reviewed. Primary objective was to compare differences between pathologic complete response(pCR) and relapse free survival(RFS) in luminal HER2-low/HER2-0 and triple negative(TNBC) HER2-low/HER2-0. Results: 855 non-HER2-positive patients were identified. Median follow-up was 59 months. 542 had luminal BC (63.4%) and 313 TNBC (36.6%). 285 (33.3%) were HER2-low. Among luminal tumors, 145 had HER2 IHC+1 (26.8%) and 91 IHC+2/ISH non-amplified (16.8%). In TNBC, only 36 had HER2 IHC+1 (11.5%) and 13 IHC+2/ISH non-amplified (4.2%). Among luminal/HER2-low and luminal/HER2-0 population, there was a high proportion of clinical T3/4 (61.5% vs 69.2%, p=0.053), node positive (74.2% vs 66.3%, p=0.27) and stage III tumors (63.1% vs 65%, p=0.51). The same was true TNBC/HER-low as compared to TNBC/HER2-0, despite a non-statistically significant higher cT4 among TNBC/HER-low (32.7% vs. 19.3%, p=0.17). pCR was 13% in luminal/HER2-low versus 9.5% in luminal/HER2-0 (p=0.27), and 51% in TNBC/HER2-low versus 47% in TNBC/HER2-0 (p=0.64). 5y RFS was 72.1% in luminal/HER2-low and 71.7% in luminal/HER2-0 (p=0.47), and 75.6% in TNBC/HER2-low versus 70.8% in TNBC/HER2-0 (p=0.23). HER2-low status was not associated with RFS in multivariate analysis (HR 0.83, 95%CI 0.6–1.11, p=0.21). Conclusion: Our data does not support HER2-low as a biologically distinct BC subtype, with no predictive effect on pCR after NACT nor prognostic value on survival outcomes.

e21143 Background: Immune checkpoint inhibitors (ICIs) are associated with durable antitumor activity in advanced non-small cell lung cancer (NSCLC), however, selection of the best candidates for this type of therapy is a challenge. PD-L1 expression, the only adequately validated predictive biomarker of response to ICIs, is imperfect, and not completely discriminatory between responders and non-responders. Gene expression profile (GEP) is a promising way to evolve in this field. The objective of this study was to identify a GEP of immune-oncology related genes, predictive of response to ICIs in NSCLC. Methods: This study analyzed two cohorts of advanced NSCLC patients treated with ICIs in any line: a discovery cohort composed of 66 Brazilian patients and a validation cohort composed of 54 Spanish patients. Clinical data were collected from medical records. Total RNA was extracted from FFPE tumor tissue. Gene expression profile (GEP) was assessed using the nCounter PanCancer IO360 panel (NanoString Technologies), which comprises 770 genes involved in the cancer immune response. LASSO regression with Cox proportional hazards approach was used to define the new gene expression signature. Results: In the discovery cohort, median age was 62.5 years (36 - 81 years). Most patients were males (57.6%), stage IV (91.9%), ECOG-PS≤1 (90.7%), smokers/former smokers (83.3%) and had adenocarcinoma histology (67.7%). The majority was treated with ICI in the first-line setting (42.4%) and nivolumab was the most frequently used drug (52.6%). At data cutoff, median follow-up for overall survival (OS - time from ICI initiation to death by any cause) was 27.7 months and for real-world progression-free survival (rwPFS - time from ICI initiation to disease progression as assessed by treating physician) was 28.2 months. The median OS and rwPFS were 17.7 months and 5.6 months, respectively. We identified a 6-gene signature (Lung Tumor Score – LungTS) that discriminate patients at low and high risk for death (median OS: 36.1 vs 15.5 months; p < 0.001) and for disease progression (median rwPFS: 10.1 vs 4.2 months; p < 0.001). Considering the expression of CD274 (PD-L1), the LungTS signature also discriminated two populations regarding OS and rwPFS (p < 0.0001). In the validation cohort, which had clinicopathological characteristics similar to the discovery cohort, the OS for high versus low LungTS was 17.0 months and 9.0 months, respectively (p = 0.004). Patients with high score also showed better rwPFS, although not statistically significant (median 10.0 versus 4.0 months; p = 0.11). Conclusions: Our study identified a novel 6-gene immune-signature predictive of response to ICI in NSCLC.

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prolonged survival in chemo-refractory patients with mCRC. Here, we investigated the role of NLR as a predictive biomarker in the CAVE mCRC trial.Methods: 77 patients enrolled in the CAVE mCRC trial, treated with cetuximab rechallenge plus avelumab, were included in the current analysis. Baseline NLR was calculated and, in line with previous findings, a cut-off value of 3 was used. Plasma samples of 67 out of 77 patients were available for analysis of circulating tumor DNA (ctDNA) mutations of KRAS, NRAS, BRAF and EGFR-S492R. Correlation of NLR<3 vs NLR 3 with median overall survival (mOS), median progression-free survival (mPFS) in the intention to treat (ITT) and ctDNA RAS/BRAF/EGFR wild-type (WT) population was performed.Results: In the ITT population, mOS was 11.6 months [95% Confidence Interval (CI), 8.4-14.8 months] and mPFS was 3.6 months (95% CI, 3.2-4.1 months). Patients with a baseline NLR < 3 (38/77, 49%) had a statistically significant improvement in mOS, 17.3 months (95% CI, 14.2-20.3), compared with patients with NLR 3 (39/77, 51%) that exhibited mOS of 8.9 months (CI 95% 6.4-11.4), (HR 0.44, CI 95% 0.25-0.76, P¼ 0.004). mPFS was 3.9 months (CI 95% 2.9-4.9) in patients with NLR < 3, compared to 3.5 months (CI 95% 2.3-4.6) in patients with NLR 3 (HR 0.71, CI 95% 0.44-1.13, P¼ 0.15). In the ctDNA WT population, mOS was not reached in the NLR < 3 group (23/ 48, 48%), whereas a mOS of 8.9 months (CI 95% 6.1-11.7), (HR 0.24, CI 95% 0.10-0.58, P¼ 0.001) was reported in patients (25/48, 52%) with NLR 3. A trend towards increased mPFS was observed in NLR < 3 population [5.2 months (CI 95% 2.9-7.6) vs 3.6 months (CI 95% 2.8-4.3) (HR 0.67, CI 95% 0.36-1.23, P¼ 0.19)]. Conclusions:In the CAVE mCRC study, baseline neutrophil to lymphocyte ratio < 3 was strongly correlated with improved survival and may represent a useful biomarker to predict response to retreatment with cetuximab plus avelumab.