LASP-1 interacts with ErbB2 in ovarian cancer cells

LASP-1 was identified as a protein following mass spectrometric analysis of phosphoproteins consequent to signaling by ErbB2 in SKOV-3 cells. It has been previously identified as an oncogene and is located on chromosomal arm 17q 0.76Mb centromeric to ErbB2. It is expressed in serous ovarian cancer cell lines as a 40kDa protein. In SKOV-3 cells, it was phosphorylated and was inhibited by Lapatinib and CP7274714. LASP-1 co-immunoprecipitated with ErbB2 in SKOV-3 cells, suggesting a direct interaction. This interaction and phosphorylation were independent of the kinase activity of ErbB2. Moreover, the binding of LASP-1 to ErbB2 was independent of the tyrosine phosphorylation of LASP-1. LASP-1 was neither expressed on the surface epithelium of the normal ovary nor in the fallopian tube. It was expressed in 28% of ovarian tumours (n=101) that did not significantly correlate with other clinical factors. In tumours from patients with invasive ductal carcinoma of the breast who had ErbB2 amplification (3+), LASP-1 was expressed in 3/20 (p <0.001). Analysis of the expression of an independent dataset of ovarian and breast tumors from TCGA showed the significant co-occurrence of ErbB2 and LASP-1 (p<0.01). These results suggest that LASP-1 and ErbB2 interaction could be important in the pathogenesis of ovarian cancer.

Real-world association of HER2/ERBB2 concordance with trastuzumab clinical benefit in advanced esophagogastric cancer

Aim: To assess concordance between HER2 status measured by traditional methods and ERBB2 amplification measured by next-generation sequencing and its association with first-line trastuzumab clinical benefit in patients with advanced esophagogastric cancer. Methods: Retrospective analysis of HER2/ ERBB2 concordance using a deidentified USA-based clinicogenomic database. Clinical outcomes were assessed for patients with HER2+ advanced esophagogastric cancer who received first-line trastuzumab. Results: Overall HER2/ ERBB2 concordance was 87.5%. Among patients who received first-line trastuzumab, concordant HER2/ ERBB2 was associated with longer time to treatment discontinuation (adjusted hazard ratio [aHR]: 0.63; 95% CI: 0.43–0.90) and overall survival (aHR: 0.51; 95% CI: 0.33–0.79). ERBB2 copy number ≥25 (median) was associated with longer time to treatment discontinuation (aHR: 0.56; 95% CI: 0.35–0.88) and overall survival (aHR: 0.52; 95% CI: 0.30–0.91). Conclusion: HER2/ ERBB2 concordance and higher ERBB2 copy number predicted clinical benefit from trastuzumab.

Imaging of Endocytic Trafficking and Extracellular Vesicles Released Under Neratinib Treatment in ERBB2+ Breast Cancer Cells

Breast cancers (BCa) with ERBB2 amplification show rapid tumor growth, increased disease progression, and lower survival rate. Deregulated intracellular trafficking and extracellular vesicle (EVs) release are mechanisms that support cancer progression and resistance to treatments. Neratinib (NE) is a Food and Drug Administration–approved pan-ERBB inhibitor employed for the treatment of ERBB2+ BCa that blocks signaling and causes survival inhibition. However, the effects of NE on ERBB2 internalization, its trafficking to multivesicular bodies (MVBs), and the release of EVs that originate from these organelles remain poorly studied. By confocal and electron microscopy, we observed that low nanomolar doses of NE induced a modest ERBB2 internalization along with an increase of clathrin-mediated endocytosis and of the CD63+ MVB compartment in SKBR-3 cells. Furthermore, we showed in the culture supernatant two distinct EV subsets, based on their size and ERBB2 positivity: small (30–100 nm) ERBB2− EVs and large (>100 nm) ERBB2+ EVs. In particular, we found that NE increased the overall release of EVs, which displayed a reduced ERBB2 positivity compared with controls. Taken together, these results provide novel insight into the effects of NE on ERBB2+ BCa cells that may lead to a reduction of ERBB2 potentially transferred to distant target cells by EVs:

Genomic alterations for novel targeted therapies in pancreatobiliary cancers from real-world data.

4124 Background: Cancers of the pancreas and biliary tract remain one of the unfavorable malignant tumors with few driver genomic alterations. Tumor-agnostic approaches are promising for cancers with poor prognosis, with some potentially actionable alterations, such as BRCA1/2 mutations, ERBB2 amplification, MSI-High, or tumor mutational burden (TMB)-High. However, co-existing alterations, clinical significance of other genomic alterations, or frequency of alterations by clinical and genomic background are unclear. Here we investigated the genomic profile in a large cohort of advanced pancreatobiliary cancers to help refine and discover new targets for improved cancer therapies. Methods: Comprehensive genomic profiling was performed at Foundation Medicine, on patients with RWD tested during the course of routine clinical care. Hybrid capture was carried out on up to 395 cancer-related genes and select introns from up to 31 genes frequently rearranged in cancer. 16,913 pancreatic cancer (PC) patients and 3,031 biliary tract cancer (BTC) patients were available for analyses and were stratified by age (≥40/ < 40), MSI status, TMB status (High ≥10/Low < 10 Muts/Mb), and select gene alterations. Using a chi-square test with Yate’s correction, frequencies of genetic alterations were analyzed according to clinical or genomic background. Results: KRAS (84.8%), TP53 (73.3%), CDKN2A (51.2%), CDKN2B (26.5%), and SMAD4 (23.2%) were frequently altered in PC patients, versus TP53 (60.6%), CDKN2A (33.5%), KRAS (27.1%), CDKN2B (20.6%) and SMAD4 (16.9%) in BTC patients. The frequency of MSI-High and TMB-High in BTC was 1.2% and 5.7%, respectively, while these were lower in PC (0.48% and 2.1%, respectively). In PC patients, the KRAS alteration rate was significantly lower in both MSI-High (57.3%, P< 0.001) and TMB-High populations (51.3%, P< 0.001). In BTC patients, the rate of ERBB2 amplification was 6.4% in TMB-High and 8.6% in TMB-Low population. Interestingly, CDK12 rearrangement was observed in BTC patients with ERBB2 amplified tumors but not in those without ERBB2 amplified tumors. In patients of pediatric/adolescents and young adults ( < 40 years old), the mutation rate of KRAS/ TP53/ CDKN2A/ SMAD4 was lower, and FGFR2 rearrangement (4%) was observed in PC patients; GATA6 amplification (11.1%) and rearrangement of BRAF (2.8%), FGFR2 (5.6%) were observed in BTC patients. Conclusions: A large real-world dataset showed differences in genomic landscape according to clinical or genomic background, and some potential targets for the development of novel drugs in advanced pancreatobiliary cancers. These findings may lead to the improvement of cancer therapies in PC and BTC patients with poor prognosis.

ARID1A mutation to predict disease progression during first-line chemotherapy in biliary tract cancer patients.

4105 Background: Biliary tract cancer (BTC) is a retractable disease showing a dismal prognosis with therapeutic resistance. There are clinical unmet needs on predicting therapeutic response and precise strategy for the patient classification according to clinically relevant tumor biology in the patients with BTC. We aimed to identify clinically detectable genomic alteration predicting therapeutic response after first-line chemotherapy in BTC using real-world data. Methods: A comprehensive genomic analysis of multi-institutional cohorts of BTC cases was performed using next-generation sequencing (NGS) with targeted DNA panel and patients’ clinicopathologic data. Results: A total of 200 BTC patients with NGS panel tests from three cancer centers were included in this study. The genomic alteration of TP53 (55.5%), KRAS (23%), ARID1A (10%), and ERBB2 amplification (10%) were the most frequent alteration events in the BTC. Pathologically-proved BTC including extrahepatic (n = 52), ampulla of Vater (n = 4), gallbladder (n = 56), intrahepatic (n = 88) cancers showed a distinct pattern of genomic alterations in terms of ARID1A for extrahepatic BTC and ERBB2 amplification, RB1, ARID2 for GB cancer, and KRAS, IDH1, PBRM1, BAP1 for intrahepatic BTC respectively (chi-square test, P < 0.05). The oncologic outcomes for progression-free and overall survival were significantly stratified according to the best response after the first-line chemotherapy (log-rank test, P < 0.001). The logistic regression test revealed that ARID1A, BRCA2, and STK11 could significantly predict disease progression during first-line chemotherapy. ARID1A, especially, was the only independent predictive marker in the multivariate regression model in total BTC (OR 3.91, 95%CI 1.25-11.66, P = 0.015) and extrahepatic BTC (OR 5.71, 95%CI 1.23-28.98, P = 0.027). The predictive performance of significant genomic alteration was enhanced with the tumor marker CA19-9 (DeLong’s test, Z = 1.933, P = 0.053, AUC 0.73, 95%CI 0.623-0.837). Conclusions: Clinically available NGS test showed distinct genomic alterations in terms of different deterioration patterns for oncogenic molecular pathways according to the anatomic locations of BTC. Integrative analysis using the data for genomic alteration and therapeutic response for the first-line chemotherapy uncover that the patients with ARID1A mutation show a significant disease progression rate during initial treatment for BTC, especially in the extrahepatic BTC. Prospective translational studies revealing underlying biology and precision strategy should be followed to improve the therapeutic response of BTC.

Genomic characteristics of breast cancer to predict response of neoadjuvant chemotherapy and long-term prognosis.

557 Background: To precisely predict neoadjuvant chemotherapy (NAC) response and long-term prognosis, we developed prediction model with clinical and genomic characteristics of breast cancer (BC). Methods: We included early and locally advanced BC that would be scheduled to receive standard NAC (four cycles of anthracycline and cyclophosphamide and four cycles of docetaxel or docetaxel plus trastuzumab for HER2+ BC) followed by curative surgery. For each patient, tumor tissue and matched blood were prospectively collected three times: at diagnosis (T1), three weeks after the first cycle of chemotherapy (T2), and curative surgery (T3). Whole exome sequencing (WES) was performed to detect somatic mutation, mutational signature and tumor mutational burden (TMB) while RNASeq with PAM50 prediction was to classify intrinsic subtype. In terms of clinical variables, clinical stage and IHC subtype at diagnosis, residual cancer burden (RCB) class and distant recurrence free survival (DRFS) were used. Logistic regression was used for predicting RCB class with clinical and genomic variables at T1. Univariate and multivariate Cox regression were performed to identify prognostic factors for DRFS. Results: In total, 210 patients were enrolled and treated with NAC as scheduled. We successfully conducted WES in 231 BC tissues (T1:117, T2:101 and T3:13) from 117 patients. In NAC response, 13 patients were in RCB class 3, 39 in class 2, 14 in class 1 and 46 in class 0. Median follow up duration was 44months and distant recurrence was observed in 13 patients. TP53 mutation (68%) was the most commonly detected genetic alteration. ARID1A, CDH1, CSMD3, LRP1B, PIK3CA, RUNX1 and TP53 were significantly mutated genes in driver gene analysis. Median TMB was 87 (range, 14-570) and signature 3 was most frequently observed. Among genetic characteristics, high TMB was significantly associated with better NAC response compared with low TMB (hazard ratio[HR] for RCB class III: 0.11, 95% confident interval[CI]: 0.01, 0.74, p = 0.05). In prediction model, combination of seven variables: intrinsic subtype, TMB, LRRK1, OPLAH, and PIK3CA hotspot mutation, ERBB2 amplification, and clinical stage had 0.83 in area under curve (AUC) and 0.75 in accuracy. High clinical stage, PTEN and PIK3CA hotspot mutation negatively affected to DRFS while high TMB had protective effect (all ps < 0.05). Prediction model made with five variables: intrinsic subtype, TMB, PTEN mutation, PIK3CA hotspot mutation and clinical stage had 0.88 in c-index (95% CI: 0.81, 0.95). Conclusions: TMB, PIK3CA hotspot mutation and clinical stage showed predictive roles on NAC response and distant recurrence of BC in NAC setting. In prediction model, intrinsic subtype, TMB, LRRK1, OPLAH, and PIK3CA hotspot mutation, ERBB2 amplification, and clinical stage affected to RCB class while intrinsic subtype, TMB, PTEN, PIK3CA hotspot mutation and clinical stage did to DRFS. Clinical trial information: NCT02591966.

Pertuzumab plus trastuzumab (P+T) in patients (Pts) with uterine cancer (UC) with ERBB2 or ERBB3 amplification, overexpression or mutation: Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) study.

5508 Background: TAPUR is a phase II basket study evaluating anti-tumor activity of commercially available targeted agents in pts with advanced cancers with genomic alterations. Results in a cohort of UC pts with ERBB2 or ERBB3 amplification , overexpression or mutation treated with P+T are reported. Methods: Eligible pts had advanced UC, no standard treatment options, measurable disease, ECOG PS 0-2, and adequate organ function. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Pts matched to P+T had UC with ERBB2 or ERBB3 amplification or overexpression or a pre-specified ERBB2 mutation. Recommended dosing was P at an initial dose of 840 mg intravenously (IV) over 60 minutes (m), then 420 mg IV over 30-60 m every 3 weeks (wks), and T at an initial dose of 8 mg/kg IV over 90 m, then 6 mg/kg IV over 30-60 m every 3 wks until disease progression. Simon 2-stage design tested the null disease control (DC) - defined as partial (PR), complete response (CR) or stable disease at 16+ weeks (SD 16+) - rate of 15% vs. 35% (power = 0.85; α = 0.10). If ≥2 of 10 pts in stage 1 have DC, 18 more pts are enrolled. If ≥7 of 28 pts have DC, the null DC rate is rejected. Secondary endpoints are progression-free survival (PFS), overall survival (OS) and safety. Results: Twenty-eight female pts were enrolled from August 2017 to November 2019; all pts were evaluable for efficacy and toxicity. Demographics and outcomes are summarized in Table. Twenty-two pts had tumors with ERBB2 amplification (21) or overexpression (1); 4 tumors had ERBB2 mutations; 1 tumor had ERBB3 amplification; 1 tumor had both an ERBB2 amplification and mutation. Two PR and 7 SD16+ were observed in pts with ERBB2 amplification, and 1 SD16+ was observed in a pt with ERBB2 V8421 mutation only (no amplification) for DC and objective response (OR) rates of 37% (95% CI, 21% to 50%) and 7.1% (95% CI, 0.8% to 24%), respectively. One pt experienced grade 3 muscle weakness at least possibly related to P+T. Conclusions: P+T demonstrated evidence of anti-tumor activity in heavily pre-treated UC pts with ERBB2 amplification or certain mutations. Additional study is warranted to confirm the efficacy of P+T in this pt population. Clinical trial information: NCT02693535. [Table: see text]