Abstract 258: MicroRNAs as biomarkers of resistance to HER2 inhibition in combination with chemotherapy in gastro-esophageal cancer

Abstract

Trastuzumab in combination with chemotherapy represents the standard of care in HER2-positive advanced gastro-esphageal cancer (GOC), but development of resistance limits response. MicroRNAs (miRs) modulate key pathways in GOC. Identification of miRs responsible for resistance to HER2 inhibition may help stratify patients, predict response and define novel strategies to restore drug sensitivity. A high-throughput LNA™ miR-inhibitor screen in HER2-positive NCI-N87 and HER2-negative FLO-1 GOC cell lines was performed in order to identify potential miRs involved in trastuzumab sensitivity/resistance. Cells were treated with a combination of cisplatin, 5FU, and trastuzumab. MiRs were considered significant if LNAs caused >40% reduction in cell viability 72 hours post treatment relative to controls with a t-test p-value of <0.001 across 3 biological replicates. Putative hits with higher baseline miR levels on nCounter® NCI-N87 cell line analysis were validated in two HER2-positive cell lines by calculating the difference (Δ) in cell viability between cells treated with trastuzumab+chemotherapy versus ‘no drug' control. MiR levels in translational samples from ten HER2-positive GOC patients recruited to the FOrMAT trial (NCT02112357) were analysed by ddPCR. MiR levels were categorized as ‘low' or ‘high' relative to median expression and correlated with clinical response. Kaplan-Meier curves for PFS and OS were generated. In NCI-N87 and FLO-1 cell lines, 59 and 37 LNAs respectively caused >40% reduction in cell viability compared to controls (p<0.001). Eighteen miRs were significant exclusively in the NCI-N87 cell line screen, suggesting potential involvement in the HER2-signaling pathway. nCounter® analysis showed 6 of these were elevated at baseline in NCI-N87: miR-1260, miR-148-3p, miR-28-3p, miR-331-3p, miR-7-5p and miR-365. Inhibition of miR-148a-3p increased sensitivity to trastuzumab + 5FU+cisplatin in both the NCI-N87 cell line (Δ 67% versus Δ 55% in the control) and OACP4C cell line (Δ 50% versus Δ 47% in the control). Patients who responded to trastuzumab + chemotherapy in FOrMAT had a trend towards lower average miR-148a-3p plasma levels than those who failed to respond. Median PFS for plasma miR-148a-3p ‘low' subgroup was 146 days versus 154 days in ‘high' subgroup. Median OS for plasma miR-148a-3p ‘low' subgroup was 357 days versus 226 days for miR-148a-3p ‘high' subgroup. Our screen identified a panel of miRs associated with GOC resistance to HER2 inhibitors in combination with chemotherapy. Inhibition of these miRs affects GOC cell viability and restores sensitivity. MiR-148a-3p emerged as a potential biomarker of resistance and further evaluation is underway in the PLATFORM trial (NCT02678182). Citation Format: Hazel Lote, Andrea Lampis, George Vlachogiannis, Jens Hahne, Sing-Yu Moorcraft, Michael Davidson, Carolin Fong, Ruwaida Begum, Matteo Fassan, Sheela Rao, David Watkins, Naureen Starling, Ian Chau, David Cunningham, Nicola Valeri. MicroRNAs as biomarkers of resistance to HER2 inhibition in combination with chemotherapy in gastro-esophageal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 258.

Resistance mechanisms to HER2-targeted therapy in gastroesophageal adenocarcinoma: A systematic review

“…Using a high-throughput miR-inhibitor screen, Lote et al described increased levels of miR-148a-3p in secondary trastuzumab resistant NCI-N87 and FLO-1 cells. Furthermore, low miR-148a-3p levels were associated with better response to trastuzumab treatment in GEA patients [108]. Others demonstrated a potential role of miRNAs in resistance to HER2 inhibition, resulting in activation of FGFRs [61,62].…”

HER2 Inhibition in Gastric Cancer—Novel Therapeutic Approaches for an Established Target

“…Other mechanisms of acquired resistance to HER2-targeted therapies include alterations in the HER2 receptor secondary to aminotruncation, resulting in the loss of the trastuzumab binding region, FGFR amplification and activation of the MAP/ERK and PI3K/mTOR downstream pathways [ 25 , 26 , 27 ]. Additionally, there is evidence that micro RNAs (miRNAs), non-coding RNAs that regulate target genes at the post-transcriptional level, may underpin trastuzumab resistance, and that serum-based miRNA signatures can distinguish trastuzumab-sensitive from resistant patients [ 28 , 29 , 30 , 31 ].…”

MicroRNAs as biomarkers for trastuzumab-based therapy in HER2-positive advanced oesophago-gastric cancer patients

“…Circulating miRs can demonstrate conflicting results: for example, circulating-tumour-miR-210 has been associated with trastuzumab response ( 45 ) and resistance ( 46 ) in HER2-positive breast cancer patients. To our knowledge, our study is the first to evaluate circulating miRs as biomarkers of response to trastuzumab-based therapy in HER2-positive advanced oesophago-gastric cancer patients ( 47 ).…”