e12579 Background: Metaplastic breast carcinoma is a rare histological subtype that has basal like characteristics and is reported to have a poorer prognosis than no specific type/ductal carcinoma (ductal/NST). We aimed to investigate clinicopathological features and outcome from a single institution based registry. Methods: Clinical records of breast cancer patients treated during 2012-2019 were screened and 31 cases of metaplastic breast carcinoma were found. Descriptive analysis was done for patients’ demographics and clinicopathological features. Kaplan Meier method was used to assess survival outcomes. Results: The incidence of metaplastic breast cancer was 0.5% (31/6180) in our study out of which the most common histopathological differentiation was squamous (45.16%). The second most common was sarcomatoid histology (32.25%), followed by chondroid (9.68%) and mixed histology (12.9%). The median age at diagnosis was 60 years ranging from 28 to 82 years. 64.15% of patients were post-menopausal. At presentation, three (9.67%) patients had metastatic disease while the rest were diagnosed with early (51.61%) and locally advanced cancers (38.72%). Triple negative cancers (ER/PR/Her2 negative) constituted the vast majority with 22 cases (80.6%) while hormone receptor positive (ER/PR positive, Her-2 negative) and Her-2 neu positive (ER/PR negative) made up the rest with three patients (9.67%) each group respectively. The median overall survival was found to be 39 months (95% CI 25.46 - 52.53). Conclusions: After a thorough search in PubMed and Google Scholar, we could not find a larger case series from India with clinical outcomes for metaplastic breast carcinoma. Our results suggest that metaplastic breast carcinoma is a heterogenous disease. Outcomes of metaplastic breast carcinoma are relatively worse when compared with literature for triple negative breast cancer and breast cancer in general. Further biological understanding may offer valuable insights for newer targets and therapeutic approaches to metaplastic breast cancer.

1078 Background: Androgen receptor (AR) expressing triple negative breast cancer (TNBC) is a sub-set of TNBC with an evolving prognostic and predictive behaviour. AR immunohistochemical threshold for positivity has not been standardized and a wide range of cut-offs have been used across studies ( > 0% to 75%). In this study we explored AR immunohistochemistry thresholds in relation to disease free survival (DFS) and clinical outcomes in non-metastatic TNBC using the Allred and H-Score systems. Increasing interest in AR as a therapeutic target for TNBC and the use of digital tissue image analysis makes it important to standardize AR immunohistochemistry reporting. Methods: 100 FFPE (formalin-fixed paraffin-embedded) tumour blocks were retrieved for non-metastatic TNBCs diagnosed between January 2015 and May 2017 and immunostained using AR441 (IgG1) mouse monoclonal antibody. Clinical follow-up ranged from 59 to 31 months and DFS was calculated. Cut-off scores were explored using Evaluate Cutpoints ( R maxstat package) and X-tile software. The score with maximum split in DFS (based on log-rank statistics and lowest p-value) was chosen as the cut-off. Descriptive and survival statistics was performed. Results: The median age was 51 (SD 11.262; range 28 to 82) years. Using Evaluate Cutpoints ≥3 was found as the threshold for AR by Allred Score. 36% cases were AR positive using Allred score (HR 0.508; CI 0.234 - 1.11; p-value 0.08). Using Evaluate Cutpoints ≥30 was found as the threshold for AR by H-Score (HR 0.624, CI 0.306 - 1.27; p-value 0.19). 35% cases were AR positive using H-Score. X-tile analysis also found the cut-offs as ≥3 and ≥30 for Allred and H-Score respectively (p < 0.05). A significant correlation was seen between the two scoring systems (Pearson Correlation 0.935; p < 0.01). A significantly higher number of grade III TNBCs were AR negative (n = 55/76) compared to grade II (n = 9/24) (p = 0.002). Cut-off for Ki67 was 75 (HR 1.61, CI 0.85-3.04, p-value 0.141) with a significantly higher number of AR negatives in the Ki67≥75 group (21/26; p < 0.05). The overall median DFS was 51.9 months. There was no significant difference in DFS for the AR negative (median: 47.4 months; mean: 39.39 months) and AR positive (Median survival not reached; mean: 41.3 months) groups(p = 0.23). Conclusions: AR immunohistochemistry cut-offs using the Allred (≥3) and H-Score (≥30) are close to the ones used for ER/PR immunohistochemistry as per ASCO/CAP guidelines, making a strong case for universal application of these systems for harmonization of AR data.

e12570 Background: Gene expression profiling for breast cancer has classified ER positive subtype into luminal A and luminal B. Luminal B breast cancer (LBBC) have a higher proliferation and poorer prognosis than luminal A tumors. Ki-67 index is the commonly used proliferation marker in breast cancer; however Ki67 expression can also be used to identify a subset of patients among LB with a favorable prognosis. This study attempts to verify this subset of LBBC patients based on DFS and PFS in non-metastatic and metastatic patients respectively. Methods: We retrospectively analyzed 80 IDC breast cancer patients diagnosed in 2013-2016 with complete follow-up till January-2021. We defined LBBC as ER+, PR+ or PR- , HER2+ or HER2- with a Ki67 index >20%. PFS was considered as the endpoint in patients presenting with metastatic disease whereas DFS was used in non-metastatic disease. The cut-off for ki67 was calculated using an X-tile plot (version 3.6.1, Yale University) by dividing Ki67 data into two populations: low and high, with randomized 1:1 “training” and “validation” cohorts. Results: Median age was 51.5 years. 18.7% (n=15) presented with metastasis at the time of diagnosis and their overall median PFS was found to be 25.8 months. The incidence of HER2 positive LBBC was found to be 15% (n=12) and none of them were found to be presented with metastasis. Survival and frequency of various sub groups in our study are enlisted in the given table. We estimated a Ki67 cut-off of 30% in patients with upfront metastatic disease and PFS was found to be higher in <30% compared to a Ki67 index >30% (38.9 months vs 19.7 months, p-0.002). Overall median DFS was not achieved in non-metastatic group (Mean DFS: 64.7 months) where as a statistically significant difference was observed in the survival of HER2 positive (median DFS: 53.5 months, mean DFS: 50.9) than HER2 negative patients (median DFS not achieved, mean: 66.97 months) ( p-0.021). We obtained a Ki67 cut-off of 32% in non- metastatic group and mean DFS was found to be higher in Ki67<32% (69 months) compared to Ki67>32% (61.4 months), however it failed to exhibit a statistically significant relationship ( p-0.373). Conclusions: Our study indicates that a subset of patients exists within metastatic and non-metastatic LBBC with differing prognosis based on Ki67. Larger studies are further required to confirm the findings and therapeutic implications.[Table: see text]

e15020 Background: Neutrophil-Lymphocyte Ratio (NLR) and Lymphocyte-Monocyte Ratio (LMR) have been under scrutiny for their potential as a prognostic tool in various cancers. While there have been conflicting opinions on their reliability, NLR has shown rather near accurate predictions in previous studies. Targeted tyrosine kinase inhibitors have shown good results in improving OS and PFS of patients with EGFR-mutated NSCLC but the prognostic indicators are limited. This study aims to decipher if baseline NLR and LMR ratios are valid tools to predict prognosis of patients with EGFR-mutated NSCLC. Methods: We analyzed 78 advanced NSCLC patients harboring Exon 19 Deletion and Exon 21 L858R mutation undergoing EGFR-TKI therapy. Baseline NLR and LMR were measured in peripheral blood within two weeks prior to the initiation of TKIs. Overall survival was used as an outcome measure for TKI therapy and it is defined as from the initiation of TKIs to death by any cause. The cut-off for NLR and LMR was calculated using an X-tile plot (version 3.6.1, Yale University, New Haven, CT, USA) by dividing marker data into three populations: low, middle, and high (i.e., two divisions), with randomized 1:1 “training” and “validation” cohorts. Results: Overall median survival of the study group was 31.5 months and median age was found to be 60 years. Gefitinib (35.9%) and afatinib (34.6%) were the most commonly prescribed followed by erlotinib (21.8%) and osimertinib (7.7%). With cut-points of 1.8 and 4.9 we analyzed three populations for baseline NLR as ≤1.8, 1.9-4.9 and > 4.9. Similarly, for LMR cut-points of 3.49 and 5 were found and we analyzed patients with LMR of ≤3.49, 3.5-5 and >5. There was a statistically significant overall median survival observed as per the obtained NLR as well as LMR cut-off as given in the table. Conclusions: A statistically significant co-relation was observed with baseline NLR and LMR ratio in predicting response to EGFR TKIs in NSCLC. Our study further strengthens the concept of using NLR and LMR as peripheral blood biomarkers for prognostic assessment in cancer patients undergoing treatment.[Table: see text]

e16269 Background: Combination of Gem+Nab-P is considered as a dose intense regimen which exhibits synergistic cytotoxic activity and equally effective in increasing survival as FOLFIRINOX regimen in pancreatic cancer. However, number of patients who tolerates such dose intense regimen is found to be less in Indian population. The importance of maintaining optimum RDI is well-known however a low RDI may reflect a poor tolerability. Therefore, the present study aimed to identify desired relative dose intensity and explore the potential of baseline NLR as a prognostic biomarker. Methods: A retrospective chart review was performed of 26 patients with a median age of 65.5 years who received this drug combination either as first-line or second-line treatment for pancreatic adenocarcinoma at a single institution. Treatment outcome was measured using overall survival and toxicities were classified according to CTCAE guidelines. The thresholds for RDI of Gem and Nab-P, and baseline NLR cut-off for predicting survival was calculated by constructing ROC curves. Results: Median overall survival was 11.5 months. Median RDI of Gem and Nab-P was found to be 79% (30-94) and 71% (39 –114) respectively. We estimated a RDI cut-off of 67% in Nab-P and 68% in Gem and observed a statistically significant favorable outcome in patients who received Nab-P with RDI > 67% ( p-0.021). No significant relationship of Gem RDI with outcome was observed. Median overall survival was found to be higher in patients with a baseline NLR < 2.35, patients on D1, D8, D15 treatment regimen and those who received Nano particle bound paclitaxel. Complete assessment of study subjects are enlisted in the table. Grade 3 neuropathy, fatigue, and hyponatremia were reported in 2, 5 and 4 patients respectively. Grade 2 skin rashes and neuropathy were seen in 3 patients each. Conclusions: Our study concludes that tolerability of Gem+Nab P is a concern and it is expected to exhibit a durable response only if it achieves an optimum RDI of Nab-P. The study indicates varied efficacy in different pharmaceutical preparations of paclitaxel favoring the use of nano-particle formulations. The study also indicates that baseline NLR is an important prognostic biomarker in pancreatic cancer[Table: see text]