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

BackgroundThis study aimed to identify microRNAs (miRs) as circulating biomarkers of resistance to first-line trastuzumab-based therapy in advanced HER2-positive oesophago-gastric cancer patients.MethodsA high-throughput 1015 Exiqon miRCURY LNA™ microRNA inhibitor library screen was performed in trastuzumab-treated HER2-positive NCI-N87 and HER2-negative FLO-1 oesophago-gastric cancer cell lines. NanoString nCounter® miR analysis was performed in NCI-N87, FLO-1, and MAGIC trial (ISRCTN93793971) formalin-fixed paraffin-embedded (FFPE) oesophago-gastric cancer patient samples. MiR-148a-3p copies in plasma samples were quantified using digital droplet polymerase chain reaction (ddPCR) from HER2-positive oesophago-gastric cancer patients treated with standard-of-care trastuzumab-based therapy within the FOrMAT (NCT02112357) and PLATFORM (NCT02678182) clinical trials. The primary endpoints were overall survival (OS) for plasma miR-148a-3p HIGH (>median) versus LOW (≤median). The secondary endpoints were progression-free survival (PFS) and 3-month progression-free rates (PFRs) miR-148a-3p HIGH versus LOW. PLATFORM sensitivity analysis normalised miR-148a-3p (NmiR-148a-3p).ResultsThe inhibition of miR-148a-3p reduced NCI-N87 relative cell viability (<0.6) and expression was high (>242) in NCI-N87 and HER2-positive MAGIC trial patients (n=5). Normalised-miR-148a-3p (NmiR-148a-3p) LOW versus HIGH demonstrated a statistically significant difference in 3-month PFRs (n=23; OR, 0.11 [0.02–0.78]; p=0.027; aOR, 0.03 [0.001–0.71], p=0.029) but no difference in OS or PFS. There was no statistically significant relationship between miR-148-3p LOW versus HIGH for OS (PLATFORM, n=62; hazard ratio [HR], 0.98 [0.57–1.66]; p=0.933; FOrMAT, n=8; HR, 0.54 [0.13–2.31]; p=0.322), PFS (n=62; HR, 1.08 [0.65–1.81]; p=0.759; FOrMAT, n=8; HR, 1.26 [0.31–5.07]; p=0.714), or PFRs (PLATFORM, n=31; odds ratio [OR], 0.67 [0.2–2.8]; p=0.577).ConclusionNormalised miR-148a-3p may be a relevant biomarker for trastuzumab-based therapy in advanced HER2-positive oesophago-gastric cancer patients

Diverse BRCA1 and BRCA2 Reversion Mutations in Circulating Cell-Free DNA of Therapy-Resistant Breast or Ovarian Cancer

Purpose:; Resistance to platinum-based chemotherapy or PARP inhibition in germline; BRCA1; or; BRCA2; mutation carriers may occur through somatic reversion mutations or intragenic deletions that restore BRCA1 or BRCA2 function. We assessed whether; BRCA1/2; reversion mutations could be identified in circulating cell-free DNA (cfDNA) of patients with ovarian or breast cancer previously treated with platinum and/or PARP inhibitors.; Experimental Design:; cfDNA from 24 prospectively accrued patients with germline; BRCA1; or; BRCA2; mutations, including 19 patients with platinum-resistant/refractory ovarian cancer and five patients with platinum and/or PARP inhibitor pretreated metastatic breast cancer, was subjected to massively parallel sequencing targeting all exons of 141 genes and all exons and introns of; BRCA1; and; BRCA2; Functional studies were performed to assess the impact of the putative; BRCA1/2; reversion mutations on BRCA1/2 function.; Results:; Diverse and often polyclonal putative; BRCA1; or; BRCA2; reversion mutations were identified in cfDNA from four patients with ovarian cancer (21%) and from two patients with breast cancer (40%).; BRCA2; reversion mutations were detected in cfDNA prior to PARP inhibitor treatment in a patient with breast cancer who did not respond to treatment and were enriched in plasma samples after PARP inhibitor therapy. Foci formation and immunoprecipitation assays suggest that a subset of the putative reversion mutations restored BRCA1/2 function.; Conclusions:; Putative; BRCA1/2; reversion mutations can be detected by cfDNA sequencing analysis in patients with ovarian and breast cancer. Our findings warrant further investigation of cfDNA sequencing to identify putative; BRCA1/2; reversion mutations and to aid the selection of patients for PARP inhibition therapy.; Clin Cancer Res; 23(21); 6708-20. ©2017 AACR;

Discovery of naturally occurring ESR1 mutations in breast cancer cell lines modelling endocrine resistance.

Resistance to endocrine therapy remains a major clinical problem in breast cancer. Genetic studies highlight the potential role of estrogen receptor-α (ESR1) mutations, which show increased prevalence in the metastatic, endocrine-resistant setting. No naturally occurring ESR1 mutations have been reported in in vitro models of BC either before or after the acquisition of endocrine resistance making functional consequences difficult to study. We report the first discovery of naturally occurring ESR1 Y537C and ESR1 Y537S mutations in MCF7 and SUM44 ESR1-positive cell lines after acquisition of resistance to long-term-estrogen-deprivation (LTED) and subsequent resistance to fulvestrant (ICIR). Mutations were enriched with time, impacted on ESR1 binding to the genome and altered the ESR1 interactome. The results highlight the importance and functional consequence of these mutations and provide an important resource for studying endocrine resistance.Cancer Research U

Reproducibility of Digital PCR Assays for Circulating Tumor DNA Analysis in Advanced Breast Cancer

<div><p>Circulating tumor DNA (ctDNA) analysis has the potential to allow non-invasive analysis of tumor mutations in advanced cancer. In this study we assessed the reproducibility of digital PCR (dPCR) assays of circulating tumor DNA in a cohort of patients with advanced breast cancer and assessed delayed plasma processing using cell free DNA preservative tubes. We recruited a cohort of 96 paired samples from 71 women with advanced breast cancer who had paired blood samples processed either immediately or delayed in preservative tubes with processing 48–72 hours after collection. Plasma DNA was analysed with multiplex digital PCR (mdPCR) assays for hotspot mutations in <i>PIK3CA</i>, <i>ESR1</i> and <i>ERBB2</i>, and for <i>AKT1</i> E17K. There was 94.8% (91/96) agreement in mutation calling between immediate and delayed processed tubes, kappa 0.88 95% CI 0.77–0.98). Discordance in mutation calling resulted from low allele frequency and likely stochastic effects. In concordant samples there was high correlation in mutant copies per ml plasma (r² = 0.98; p<0.0001). There was elevation of total cell free plasma DNA concentrations in 10.3% of delayed processed tubes, although overall quantification of total cell free plasma DNA had similar prognostic effects in immediate (HR 3.6) and delayed (HR 3.0) tubes. There was moderate agreement in changes in allele fraction between sequential samples in quantitative mutation tracking (r = 0.84, p = 0.0002). Delayed processing of samples using preservative tubes allows for centralized ctDNA digital PCR mutation screening in advanced breast cancer. The potential of preservative tubes in quantitative mutation tracking requires further research.</p></div

Mutation frequency observed in advanced breast cancer.

<p>A. Mutation frequency observed in plasma of patients with advanced cancer. Only samples with concordant mutations in both samples are assessed as having a mutation. Individual mutations observed for B. <i>PIK3CA</i> and C. <i>ESR1</i> mutations detected.</p

Comparison of total free plasma DNA levels between immediate processed EDTA samples and delayed processed Streck samples.

<p>A. Correlation plasma DNA levels of immediate processed EDTA samples and delayed processed Streck samples. Pearson correlation coefficient. B. Bland-Altman plot of data in part A with dashed lines representing 95% CI. C. Overall survival with plasma DNA quantified in immediate EDTA tubes divided on high plasma DNA levels above the upper quartile versus low plasma DNA below the upper quartile. Log rank test with hazard ratio (HR) and 95% confidence intervals (95% CI). D. Overall survival with plasma DNA quantified in delayed Streck tubes divided on high plasma DNA levels above the upper quartile versus low plasma DNA below the upper quartile. Log rank test with hazard ratio.</p

Early circulating tumor DNA dynamics and clonal selection with palbociclib and fulvestrant for breast cancer

Circulating tumor DNA (ctDNA) may provide a prediction of treatment response, but could be impacted by tumor heterogeneity. Here, the authors investigate ctDNA in CDK4/6 inhibitor treatment in advanced breast cancer, finding ctDNA levels predict progression-free survival and anticipate clonal selection

Agreement in change in mutation abundance in sequential samples between immediate EDTA and delayed Streck samples.

<p>A. Agreement in fold change in mutation allele frequency between immediate and delayed samples in sequential samples from 6 patients (r = 0.85, p = 0.0002). B. Agreement in fold change in mutant copies per ml between immediate and delayed samples in sequential samples from 6 patients (r = 0.84, p = 0.0003).</p

Clinical and pathological characteristics of study patients.

<p>Clinical and pathological characteristics of study patients.</p