Surgery (RMH) - Research Publications
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ItemPrecision oncology using a clinician-directed, tailored approach to molecular profiling(WILEY, 2018-02)AIM: Precision oncology involves molecularly matching patients to targeted agents usually in early drug development (EDD) programs. Molecular profiling (MP) identifies actionable targets. Comprehensive commercial MP platforms are costly and in resource limited environments, a more practical approach to MP is necessary to support EDD and precision oncology. We adopted a clinician-directed, tailored approach to MP to enrol patients onto molecularly targeted trials. We report the feasibility of this approach. METHODS: All patients referred to the Royal Melbourne Hospital (RMH) EDD between September 2013 and September 2015 were identified in a prospective database. Key captured data included clinicopathological data, MP platform ordered (if any), molecular targets identified and subsequent enrolment onto clinical trials. EDD-clinician decisions to order MP and the platform utilized was guided by patient consultation, tumor type, trial availability and requirement for molecular information. RESULTS: We identified 377 patients referred to RMH EDD. A total of 216 (57%) had MP ordered. The remainder had known actionable targets (19%), or were inappropriate for clinical trials (24%). In those undergoing MP, 187 genetic aberrations were found in 113 patients with 98 considered actionable targets in 86 patients. Ninety-eight (25%) patients were enrolled onto a clinical trial, including 40 (11%) receiving molecularly matched treatments. Median progression-free survival was improved in patients enrolled onto molecularly matched trials compared to those on unmatched trials (3.6 months vs 1.9 months, HR 0.58 [0.38-0.89], P = 0.013). CONCLUSION: A clinician-directed, tailored approach to the use of MP is feasible, resulting in 11% of patients enrolled onto molecularly matched trials.
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ItemChemotherapy and biologic use in the routine management of metastatic colorectal cancer in Australia: is clinical practice following the evidence?(WILEY, 2019-04)BACKGROUND: Emerging evidence on the optimal use of chemotherapy and biologics in patients with metastatic colorectal cancer should impact management in routine care. Recent studies have demonstrated benefits for initial triplet chemotherapy (5-fluorouracil, oxaliplatin and irinotecan, FOLFOXIRI) and for initial treatment with an epidermal growth factor receptor inhibitor (EGFRi) in patients with a RAS wild-type tumour and a left-sided primary tumour. AIM: To explore evolving pattern of metastatic colorectal cancer care over time in Australia. METHODS: We analysed data from the Treatment of Recurrent and Advanced Colorectal Cancer registry. RESULTS: From July 2009 to December 2017, 2552 metastatic colorectal cancer patients were entered into the Treatment of Recurrent and Advanced Colorectal Cancer registry. Of 1585 patients who initially underwent chemotherapy, treatment was with a doublet in 76%. FOLFOXIRI was given to 22 patients (1.4%), mostly young patients and those with potentially resectable disease. Along with first-line chemotherapy, 61% received bevacizumab, while 3.3% received an EGFRi, predominantly over the last 2 years. Within the KRAS wild-type left-sided tumour cohort, EGFRi use increased from 9% in 2015 to 37% in 2017. Across treatment sites, there was a wide variation in the utilisation of FOLFOXIRI and EGFRi therapy; bevacizumab use was more consistent. A clear impact on survival outcomes from these regimens is not evident, potentially due to multiple confounders. CONCLUSION: Doublet chemotherapy + bevacizumab remains the dominant initial strategy, with limited uptake of triplet chemotherapy and of EGFRi. Potential explanations include uncertainty about the significance of post hoc analyses for EGFRi and concerns regarding adverse events for both strategies.
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ItemRight versus left sided metastatic colorectal cancer: Teasing out clinicopathologic drivers of disparity in survival(WILEY, 2019-06)BACKGROUND: Metastatic colorectal cancer (mCRC) patients with a right-sided primary (RC) have an inferior survival to mCRC arising from a left-sided primary (LC). Previous analyses have suggested multiple factors contribute. METHODS: The Treatment of Recurrent and Advanced Colorectal Cancer (TRACC) Registry prospectively captured data on consecutive mCRC patients. RC were defined as tumors proximal to the splenic flexure; LC were those at and distal to the splenic flexure and included rectal cancers. Patient, tumor, treatment, and survival data were analyzed stratified by side. RESULTS: Of 2306 patients enrolled from July 2009-March 2018, 747 (32%) had an RC. Patients with RC were older, more likely to be female and have a Charlson score ≥3. RC were more frequently BRAF mutated, deficient in mismatch repair, associated with peritoneal metastases, and less likely to receive chemotherapy. Progression-free survival on first-line systemic therapy was inferior for RC patients (8.1 vs. 10.8 months, hazard ratio [HR] for progression in RC 1.38, P < 0.001). Median overall survival for all RC patients was inferior (19.6 vs. 27.5 months, HR for death in RC 1.44, P < 0.001), and inferior within the treated (21 vs. 29.5 months, HR 1.52, P < 0.001) and untreated subgroups (5.9 vs. 10.3 months, HR 1.38, P = 0.009). Primary side remained a significant factor for overall survival in multivariate analysis. CONCLUSION: Our data from a real-world population confirms the poorer prognosis associated with RC. Primary tumor location remains significantly associated with overall survival even when adjusting for multiple factors, indicating the existence of further side-based differences that are as yet undefined.
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ItemDifferent APC genotypes in proximal and distal sporadic colorectal cancers suggest distinct WNT/β-catenin signalling thresholds for tumourigenesis(NATURE PUBLISHING GROUP, 2013-09-26)Biallelic protein-truncating mutations in the adenomatous polyposis coli (APC) gene are prevalent in sporadic colorectal cancer (CRC). Mutations may not be fully inactivating, instead producing WNT/β-catenin signalling levels 'just-right' for tumourigenesis. However, the spectrum of optimal APC genotypes accounting for both hits, and the influence of clinicopathological features on genotype selection remain undefined. We analysed 630 sporadic CRCs for APC mutations and loss of heterozygosity (LOH) using sequencing and single-nucleotide polymorphism microarrays, respectively. Truncating APC mutations and/or LOH were detected in 75% of CRCs. Most truncating mutations occurred within a mutation cluster region (MCR; codons 1282-1581) leaving 1-3 intact 20 amino-acid repeats (20AARs) and abolishing all Ser-Ala-Met-Pro (SAMP) repeats. Cancers commonly had one MCR mutation plus either LOH or another mutation 5' to the MCR. LOH was associated with mutations leaving 1 intact 20AAR. MCR mutations leaving 1 vs 2-3 intact 20AARs were associated with 5' mutations disrupting or leaving intact the armadillo-repeat domain, respectively. Cancers with three hits had an over-representation of mutations upstream of codon 184, in the alternatively spliced region of exon 9, and 3' to the MCR. Microsatellite unstable cancers showed hyper-mutation at MCR mono- and di-nucleotide repeats, leaving 2-3 intact 20AARs. Proximal and distal cancers exhibited different preferred APC genotypes, leaving a total of 2 or 3 and 0 to 2 intact 20AARs, respectively. In conclusion, APC genotypes in sporadic CRCs demonstrate 'fine-tuned' interdependence of hits by type and location, consistent with selection for particular residual levels of WNT/β-catenin signalling, with different 'optimal' thresholds for proximal and distal cancers.
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ItemMultiple Common Susceptibility Variants near BMP Pathway Loci GREM1, BMP4, and BMP2 Explain Part of the Missing Heritability of Colorectal Cancer(PUBLIC LIBRARY SCIENCE, 2011-06)Genome-wide association studies (GWAS) have identified 14 tagging single nucleotide polymorphisms (tagSNPs) that are associated with the risk of colorectal cancer (CRC), and several of these tagSNPs are near bone morphogenetic protein (BMP) pathway loci. The penalty of multiple testing implicit in GWAS increases the attraction of complementary approaches for disease gene discovery, including candidate gene- or pathway-based analyses. The strongest candidate loci for additional predisposition SNPs are arguably those already known both to have functional relevance and to be involved in disease risk. To investigate this proposition, we searched for novel CRC susceptibility variants close to the BMP pathway genes GREM1 (15q13.3), BMP4 (14q22.2), and BMP2 (20p12.3) using sample sets totalling 24,910 CRC cases and 26,275 controls. We identified new, independent CRC predisposition SNPs close to BMP4 (rs1957636, P = 3.93×10(-10)) and BMP2 (rs4813802, P = 4.65×10(-11)). Near GREM1, we found using fine-mapping that the previously-identified association between tagSNP rs4779584 and CRC actually resulted from two independent signals represented by rs16969681 (P = 5.33×10(-8)) and rs11632715 (P = 2.30×10(-10)). As low-penetrance predisposition variants become harder to identify-owing to small effect sizes and/or low risk allele frequencies-approaches based on informed candidate gene selection may become increasingly attractive. Our data emphasise that genetic fine-mapping studies can deconvolute associations that have arisen owing to independent correlation of a tagSNP with more than one functional SNP, thus explaining some of the apparently missing heritability of common diseases.
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ItemPhase II trial of selective internal radiation therapy and systemic chemotherapy for liver-predominant metastases from pancreatic adenocarcinoma(BMC, 2015-10-26)BACKGROUND: This prospective, open-label phase II study assessed the impact of liver-directed therapy with selective internal radiation therapy (SIRT) and systemic chemotherapy on progression-free survival (PFS) in liver-dominant metastatic pancreatic adenocarcinoma. METHODS: Patients received yttrium-90-labelled ((90)Y) resin microspheres (SIR-Spheres; Sirtex Medical Limited, Sydney, Australia) as a single procedure on day 2 of the first weekly cycle of 5-fluorouracil (5FU; 600 mg/m(2)) with the option to switch to gemcitabine (1000 mg/m(2)) after 8 weeks of 5FU. Statistical analysis was conducted using Microsoft Excel (Microsoft Corporation, Redmond, Washington, USA). The primary endpoint of the study was PFS in the liver, with a median of ≥ 16 weeks defined as the threshold for clinical significance. PFS and overall survival (OS) were summarised by the Kaplan-Meier method using non-parametric estimates of the survivor function. RESULTS: Fourteen eligible patients were enrolled; ten had primary tumour in situ and eight had liver-only metastases. Patients received a median (90)Y activity of 1.1 GBq and 8 weekly doses of 5FU; seven patients received a median of two doses of gemcitabine. Disease control in the liver was 93% (two confirmed partial responses [PR], one unconfirmed PR, ten stable disease). Median reduction in cancer antigen 19-9 was 72%. Median PFS was 5.2 months in the liver, which met the primary endpoint of the study, and 4.4 months at any site. PFS was prolonged in those with a resected primary compared with patients with primary in situ (median 7.8 vs. 3.4 months; p = 0.017). Median OS was 5.5 months overall and 13.6 months in patients with a resected primary. Grade 3/4 adverse events occurred in eight (57%) patients during days 0-60. There was one sudden death and another patient who died from possible treatment-related liver failure 7.0 months after SIRT. CONCLUSIONS: SIRT and chemotherapy appears to be an effective treatment for liver metastases from pancreatic cancer, likely to be of most benefit in selected patients with a resected primary tumour and liver only disease. Significant toxicity was observed and the safety of this approach in patients with metastatic pancreatic cancer will need to be confirmed in subsequent studies. Further study is warranted with SIRT and modern chemotherapies. TRIAL REGISTRATION: ACTRN12606000015549.
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ItemWild-type APC predicts poor prognosis in microsatellite-stable proximal colon cancer(NATURE PUBLISHING GROUP, 2015-09-15)BACKGROUND: APC mutations (APC-mt) occur in ∼70% of colorectal cancers (CRCs), but their relationship to prognosis is unclear. METHODS: APC prognostic value was evaluated in 746 stage I-IV CRC patients, stratifying for tumour location and microsatellite instability (MSI). Microarrays were used to identify a gene signature that could classify APC mutation status, and classifier ability to predict prognosis was examined in an independent cohort. RESULTS: Wild-type APC microsatellite stable (APC-wt/MSS) tumours from the proximal colon showed poorer overall and recurrence-free survival (OS, RFS) than APC-mt/MSS proximal, APC-wt/MSS distal and APC-mt/MSS distal tumours (OS HR⩾1.79, P⩽0.015; RFS HR⩾1.88, P⩽0.026). APC was a stronger prognostic indicator than BRAF, KRAS, PIK3CA, TP53, CpG island methylator phenotype or chromosomal instability status (P⩽0.036). Microarray analysis similarly revealed poorer survival in MSS proximal cancers with an APC-wt-like signature (P=0.019). APC status did not affect outcomes in MSI tumours. In a validation on 206 patients with proximal colon cancer, APC-wt-like signature MSS cases showed poorer survival than APC-mt-like signature MSS or MSI cases (OS HR⩾2.50, P⩽0.010; RFS HR⩾2.14, P⩽0.025). Poor prognosis APC-wt/MSS proximal tumours exhibited features of the sessile serrated neoplasia pathway (P⩽0.016). CONCLUSIONS: APC-wt status is a marker of poor prognosis in MSS proximal colon cancer.
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ItemA phase I trial of imatinib in combination with mFOLFOX6-bevacizumab in patients with advanced colorectal cancer(SPRINGER, 2013-02)PURPOSE: Platelet-derived growth factor receptor (PDGFR) inhibition by reducing tumoral interstitial fluid pressure might increase the efficacy of chemotherapy. Imatinib inhibits PDGFR kinase activity at therapeutically relevant doses. This phase I study aimed to assess the maximal tolerated dose (MTD) of imatinib in combination with mFOLFOX6-bevacizumab in patients with advanced colorectal cancer and to identify pharmacokinetic (PK) interactions and toxicities. METHODS: Eligible patients had measurable disease and adequate organ function. On day-14, patients commenced imatinib daily plus bevacizumab (5 mg/kg/2 weekly). Two weeks later (day 1), patients were also treated with full dose mFOLFOX6-bevacizumab for 12 cycles. Blood samples were taken for PK. DLTs defined in the first 6 weeks. Standard dose escalation of imatinib, with 3 patient cohorts: planned dose levels (DL): DL1; 400 mg, DL2; 600 mg, DL3; 800 mg daily. RESULTS: Ten patients enrolled. DL1 3 patients, DL2 7 patients. DLTs observed in 3 of 6 patients in DL2: febrile neutropenia (2); Grade 3 infection and Grade 4 neutropenia (1). Neutropenia was most frequent AEs: Grade 3/4 in >60 % of patients overall. In DL2 pts, imatinib clearance was reduced post-chemotherapy (P < 0.05). Oxaliplatin and 5FU PK unchanged by imatinib. CONCLUSIONS: MTD was imatinib 400 mg plus full dose mFOLFOX-bevacizumab. Dose escalation of imatinib limited by neutropenia. Further study is warranted as imatinib can be delivered at levels that inhibit PDGFR.
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ItemNo Preview AvailableSMAD2, SMAD3 and SMAD4 Mutations in Colorectal Cancer(AMER ASSOC CANCER RESEARCH, 2013-01-15)Activation of the canonical TGF-β signaling pathway provides growth inhibitory signals in the normal intestinal epithelium. Colorectal cancers (CRCs) frequently harbor somatic mutations in the pathway members TGFBR2 and SMAD4, but to what extent mutations in SMAD2 or SMAD3 contribute to tumorigenesis is unclear. A cohort of 744 primary CRCs and 36 CRC cell lines were sequenced for SMAD4, SMAD2, and SMAD3 and analyzed for allelic loss by single-nucleotide polymorphism (SNP) microarray analysis. Mutation spectra were compared between the genes, the pathogenicity of mutations was assessed, and relationships with clinicopathologic features were examined. The prevalence of SMAD4, SMAD2, and SMAD3 mutations in sporadic CRCs was 8.6% (64 of 744), 3.4% (25 of 744), and 4.3% (32 of 744), respectively. A significant overrepresentation of two genetic hits was detected for SMAD4 and SMAD3, consistent with these genes acting as tumor suppressors. SMAD4 mutations were associated with mucinous histology. The mutation spectra of SMAD2 and SMAD3 were highly similar to that of SMAD4, both in mutation type and location within the encoded proteins. In silico analyses suggested the majority of the mutations were pathogenic, with most missense changes predicted to reduce protein stability or hinder SMAD complex formation. The latter altered interface residues or disrupted the phosphorylation-regulated Ser-Ser-X-Ser motifs within SMAD2 and SMAD3. Functional analyses of selected mutations showed reductions in SMAD3 transcriptional activity and SMAD2-SMAD4 complex formation. Joint biallelic hits in SMAD2 and SMAD3 were overrepresented and mutually exclusive to SMAD4 mutation, underlining the critical roles of these three proteins within the TGF-β signaling pathway.