Related Publications


QUB

EphA2 expression is a key driver of migration and invasion and a poor prognostic marker in colorectal cancer.
Dunne PD, Dasgupta S, Blayney J, McArt DG, Redmond KL, Weir JA, Bradley CA, Sasazuki T, Shirasawa S, Wang T, Srivastava S, Ong CW, Arthur K, Salto-Tellez M, Wilson RH, Johnston PG, Van Schaeybroeck S

Clin Cancer Res. 2015 Aug 17. pii: clincanres.0603.2015.

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PURPOSE: EphA2, a member of the Eph receptor tyrosine kinases family, is an important regulator of tumour initiation, neo-vascularization and metastasis in a wide range of epithelial and mesenchymal cancers, however its role in colorectal cancer (CRC) recurrence and progression is unclear.

RESULTS: Colorectal tumours displayed significantly higher expression levels of EphA2 compared with matched normal tissue, which positively correlated with high CD44 and Lgr5 expression levels. Moreover, high EphA2 mRNA and protein expression were found to be associated with poor overall survival in stage II/III CRC tissues, in both univariate and multivariate analyses. Pre-clinically, we found that EphA2 was highly expressed in KRASMT CRC cells and that EphA2 levels are regulated by the KRAS-driven MAPK and RalGDS-RalA pathways. Moreover, EphA2 levels were elevated in several invasive daughter cell lines and down-regulation of EphA2 using RNAi or recombinant EFNA1, suppressed migration and invasion of KRASMT CRC cells.

CONCLUSIONS: These data show that EpHA2 is a poor prognostic marker in stage II/III CRC, which may be due to its ability to promote cell migration and invasion, providing support for the further investigation of EphA2 as a novel prognostic biomarker and therapeutic target.

HDAC Inhibition Overcomes Acute Resistance to MEK Inhibition in BRAF-Mutant Colorectal Cancer by Downregulation of c-FLIPL
Robbie Carson, Basak Celtikci, Cathy Fenning, Arman Javadi, Nyree Crawford, Lucia Perez-Carbonell, Mark Lawler, Daniel B. Longley, Patrick G. Johnston, and Sandra Van Schaeybroeck

Clin Cancer Res July 15, 2015 21; 3230

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Purpose: Activating mutations in the BRAF oncogene are found in 8% to 15% of colorectal cancer patients and have been associated with poor survival. In contrast with BRAF-mutant (MT) melanoma, inhibition of the MAPK pathway is ineffective in the majority of BRAFMT colorectal cancer patients. Therefore, identification of novel therapies for BRAFMT colorectal cancer is urgently needed.

Results: Increased c-MET-STAT3 signaling was identified as a novel adaptive resistance mechanism to MEK inhibitors (MEKi) in BRAFMT colorectal cancer models in vitro and in vivo. Moreover, MEKi treatment resulted in acute increases in transcription of the endogenous caspase-8 inhibitor c-FLIPL in BRAFMT cells, but not in BRAFWT cells, and inhibition of STAT3 activity abrogated MEKi-induced c-FLIPL expression. In addition, treatment with c-FLIP–specific siRNA or HDAC inhibitors abrogated MEKi-induced upregulation of c-FLIPL expression and resulted in significant increases in MEKi-induced cell death in BRAFMT colorectal cancer cells. Notably, combined HDAC inhibitor/MEKi treatment resulted in dramatically attenuated tumor growth in BRAFMT xenografts.

Conclusions: Our findings indicate that c-MET/STAT3-dependent upregulation of c-FLIPL expression is an important escape mechanism following MEKi treatment in BRAFMT colorectal cancer. Thus, combinations of MEKi with inhibitors of c-MET or c-FLIP (e.g., HDAC inhibitors) could be potential novel treatment strategies for BRAFMT colorectal cancer.

Probing a 3,4′-bis-guanidinium diaryl derivative as an allosteric inhibitor of the Ras pathway
Elena Diez-Ceciliaa, Robert Carsonb, Brendan Kellya, Sandra van Schaeybroeckb, James T. Murrayc, Isabel Rozasa

Bioorg Med Chem Lett. 2015 Oct 1;25(19):4287-92.

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Mutations in the Ras-pathway occur in 40-45% of colorectal cancer patients and these are refractory to treatment with anti-EGFR-targeted therapies. With this in mind, we have studied novel guanidinium-based compounds with demonstrated ability to inhibit protein kinases. We have performed docking studies with several proteins involved in the Ras-pathway and evaluated 3,4′-bis-guanidinium derivatives as inhibitors of B-Raf. Compound 3, the most potent in this series, demonstrated strong cytotoxicity in (WT)B-Raf colorectal cancer cells and also cells with (V600E)B-Raf mutations. Cell death was induced by apoptosis, detected by cleavage of PARP. Compound 3 also potently inhibited ERK1/2 signalling, inhibited EGFR activation, as well as Src, STAT3 and AKT phosphorylation. Mechanistically, compound 3 did not inhibit ATP binding to B-Raf, but direct assay of B-Raf activity was inhibited in vitro. Summarizing, we have identified a novel B-Raf type-III inhibitor that exhibits potent cellular cytotoxicity.

The prognostic value of the stem-like group in colorectal cancer using a panel of immunohistochemistry markers
Ong CW, Chong PY, McArt DG, Chan JY, Tan HT, Kumar AP, Chung MC, Clément MV, Soong R, Van Schaeybroeck S, Waugh DJ, Johnston PG, Dunne PD, Salto-Tellez M.

Oncotarget. 2015 May 20;6(14):12763-73.

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Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the Western world. It is becoming increasingly clear that CRC is a diverse disease, as exemplified by the identification of subgroups of CRC tumours that are driven by distinct biology. Recently, a number of studies have begun to define panels of diagnostically relevant markers to align patients into individual subgroups in an attempt to give information on prognosis and treatment response. We examined the immunohistochemical expression profile of 18 markers, each representing a putative role in cancer development, in 493 primary colorectal carcinomas using tissue microarrays. Through unsupervised clustering in stage II cancers, we identified two cluster groups that are broadly defined by inflammatory or immune-related factors (CD3, CD8, COX-2 and FOXP3) and stem-like factors (CD44, LGR5, SOX2, OCT4). The expression of the stem-like group markers was associated with a significantly worse prognosis compared to cases with lower expression. In addition, patients classified in the stem-like subgroup displayed a trend towards a benefit from adjuvant treatment. The biologically relevant and poor prognostic stem-like group could also be identified in early stage I cancers, suggesting a potential opportunity for the identification of aggressive tumors at a very early stage of the disease.

Is precision medicine the route to a healthy world?
Horgan D, Paradiso A, McVie G, Banks I, Van der Wal T, Brand A, Lawler M

Lancet. 2015 Jul 25;386(9991):336-7.

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In their letter, John Coote and Michael Joyner argue that “Although precision medicine will almost certainly be used in niche applications, if widely implemented, it could be a distraction from low-cost and effective population-wide interventions and policies”, adding, “We believe precision medicine is not the route to a healthy world and instead urge a renewed and increased focus on public health and prevention”.

Changing the Paradigm-Multistage Multiarm Randomized Trials and Stratified Cancer Medicine.
Lawler M, Kaplan R, Wilson RH, Maughan T; S-CORT Consortium.

Oncologist. 2015 Aug;20(8):849-51.

Silencing the voice of scientific reason.
Lawler M.

Lancet Oncol. 2015 Jan;16(1):e4-5.

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In view of the central role of science in underpinning advances in cancer research and cancer care, the decision by the new President of the European Commission Jean-Claude Juncker to sack Anne Glover, the EU Chief Scientific Adviser, is baffling. As detailed in this journal, Glover, a noted cell biologist from the University of Aberdeen (Aberdeen, UK), was appointed Chief Scientific Adviser by previous President José Manuel Barroso. It would seem that her intelligence, integrity, and insight are the very qualities that led to her position being axed.

PDUM

PIK3CA mutations predict recurrence in localized microsatellite stable colon cancer

Gilles Manceau, et al.

Cancer Med. 2015 Mar;4(3):371-82.

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Abstract: PIK3CA, which encodes the p110α catalytic subunit of PI3Kα, is one of the most frequently altered oncogenes in colon cancer (CC), but its prognostic value is still a matter of debate. Few reports have addressed the association between PIK3CA mutations and survival and their results are controversial. In the present study, we aimed to clarify the prognostic impact of PIK3CA mutations in stage I-III CC according to mismatch repair status. Fresh frozen tissue samples from two independent cohorts with a total of 826 patients who underwent curative surgical resection of CC were analyzed for microsatellite instability and screened for activating point mutations in exon 9 and 20 of PIK3CA by direct sequencing. Overall, 693 tumors (84%) exhibited microsatellite stability (MSS) and 113 samples (14%) harbored PIK3CA mutation. In the retrospective training cohort (n = 433), patients with PIK3CA-mutated MSS tumors (n = 47) experienced a significant increased 5-year relapse-free interval compared with PIK3CA wild-type MSS tumors (n = 319) in univariate analysis (94% vs. 68%, Log-rank P = 0. 0003) and in multivariate analysis (HR = 0.12; 95% confidence interval, 0.029-0.48; P = 0.0027). In the prospective validation cohort (n = 393), the favorable prognostic impact of PIK3CA mutations in MSS tumors (n = 327) was confirmed (83% vs. 67%, Log-rank P = 0.04). Our study showed that PIK3CA mutations are associated with a good prognosis in patients with MSS stage I-III CC.

STRATEGIC-1: A multiple-lines, randomized, open-label GERCOR phase III study in patients with unresectable wild-type RAS metastatic colorectal cancer.

Chibaudel B, Bonnetain F, Tournigand C, de Larauze MH, de Gramont A, Laurent-Puig P, Paget J, Hadengue A, Notelet D, Benetkiewicz M, André T, de Gramont A.

BMC Cancer. 2015 Jul 4;15:496.

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Background The management of unresectable metastatic colorectal cancer (mCRC) is a comprehensive treatment strategy involving several lines of therapy, maintenance, salvage surgery, and treatment-free intervals. Besides chemotherapy (fluoropyrimidine, oxaliplatin, irinotecan), molecular-targeted agents such as anti-angiogenic agents (bevacizumab, aflibercept, regorafenib) and anti-epidermal growth factor receptor agents (cetuximab, panitumumab) have become available. Ultimately, given the increasing cost of new active compounds, new strategy trials are needed to define the optimal use and the best sequencing of these agents. Such new clinical trials require alternative endpoints that can capture the effect of several treatment lines and be measured earlier than overall survival to help shorten the duration and reduce the size and cost of trials.

Methods/Design STRATEGIC-1 is an international, open-label, randomized, multicenter phase III trial designed to determine an optimally personalized treatment sequence of the available treatment modalities in patients with unresectable RAS wild-type mCRC. Two standard treatment strategies are compared: first-line FOLFIRI-cetuximab, followed by oxaliplatin-based second-line chemotherapy with bevacizumab (Arm A) vs. first-line OPTIMOX-bevacizumab, followed by irinotecan-based second-line chemotherapy with bevacizumab, and by an anti-epidermal growth factor receptor monoclonal antibody with or without irinotecan as third-line treatment (Arm B). The primary endpoint is duration of disease control. A total of 500 patients will be randomized in a 1:1 ratio to one of the two treatment strategies.

Discussion The STRATEGIC-1 trial is designed to give global information on the therapeutic sequences in patients with unresectable RAS wild-type mCRC that in turn is likely to have a significant impact on the management of this patient population. The trial is open for inclusion since August 2013.

Trial registration STRATEGIC-1 is registered at Clinicaltrials.gov: NCT01910610, 23 July, 2013. STRATEGIC-1 is registered at EudraCT-No.: 2013-001928-19, 25 April, 2013.

Expression of pEGFR and pAKT as response-predictive biomarkers for RAS wild-type patients to anti-EGFR monoclonal antibodies in metastatic colorectal cancers.

Harlé A, Salleron J, Perkins G, Pilati C, Blons H, Laurent-Puig P, Merlin JL.

Br J Cancer. 2015 Aug 11;113(4):680-5.

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Background RAS wild-type (RASw/t) tumours have been associated with better outcomes in patients with metastatic colorectal cancer (mCRC) treated with anti-EGFR monoclonal antibodies (mAb). We investigated the expression of EGFR downstream proteins under their active phosphorylated forms as potential markers in response to these patients.

Methods One-hundred tumour samples were collected from patients with mCRC refractory to FOLFOX and/or FOLFIRI and treated by a combination of chemotherapy with anti-EGFR mAb. The outcomes were measured on response evaluation criteria in solid tumour (RECIST), progression-free survival (PFS) and overall survival (OS). All samples were assessed for RAS and BRAF mutations, and the key phosphorylated proteins of EGFR downstream signalling were quantitatively analysed using the BioPlex Protein array.

Results Among the 60 RASw/t patients, 45.0% achieved a complete or partial response when treated with anti-EGFR mAb. Expression of pAKT, pERK1/2 and pMEK1 was significantly lower in RASw/t patients (P=0.0246; P=0.004; P=0.0110, respectively). The response rate was significantly higher for RASw/t patients who express pEGFR and pAKT (P=0.0258; P=0.0277, respectively).

Conclusions Overexpression of pEGFR and pAKT may predict the response rate in RASw/t patients treated with anti-EGFR mAb. On the basis of our results, we hypothesise that the association of anti-EGFR mAb and anti-AKT therapies could be of interest.

VHIO

First-Line Treatment of Metastatic Colorectal Cancer: Interpreting FIRE-3, PEAK, and CALGB/SWOG 80405.

Elez E, Argilés G, Tabernero J.

Curr Treat Options Oncol. 2015 Nov;16(11):52.

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The advances made in the therapeutic management of colorectal cancer (CRC) over recent years with the addition of therapies targeting angiogenesis or cell proliferation have positioned bevacizumab, cetuximab, and panitumumab as accepted first-line treatments when combined with FOLFOX or FOLFIRI for RAS wild-type (WT) metastatic CRC. The question has been raised as to the choice of targeted therapy to maximize chances of an optimal outcome. Three studies, the phase III FIRE-3 (AIO KRK-0306), the phase II PEAK, and the recently presented phase III CALGB/SWOG 80405 trial, have addressed this issue face-on, directly comparing the addition of bevacizumab versus cetuximab or panitumumab to FOLFOX/FOLFIRI in terms of efficacy outcomes. None of these studies met their primary endpoint (response rate, progression-free survival or overall survival respectively), meaning we are no closer to being able to categorically define an optimal targeted treatment in the first-line setting for patients with advanced CRC. This led to reflection over study design and further analyses, raising a number of important issues. High-sensitivity analysis of the mutational status of exons identified a population with a “pure” non-RAS-mutated profile showing benefit with anti-epidermal growth factor receptor (anti-EGFR) combinations, particularly in the context of early and greater depth of response. Coherent with a personalized therapeutic approach, the importance of performing individual high-sensitivity extended RAS testing is unequivocal and is currently a requirement in many countries to identify this all-RAS WT population, thus limiting unnecessary exposure and expense in patients unlikely to respond. These three studies, particularly the CALGB/SWOG 80405 trial, mark an important milestone in the roadmap of metastatic CRC treatment, highlighting the need for close analysis to fully exploit the available data.

A Randomized Phase II/III Study of Dalotuzumab in Combination With Cetuximab and Irinotecan in Chemorefractory, KRAS Wild-Type, Metastatic Colorectal Cancer.

Sclafani F, et al.

J Natl Cancer Inst. 2015 Sep 23;107(12).

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Background Insulin-like growth factor type 1 receptor (IGF-1R) mediates resistance to epidermal growth factor receptor (EGFR) inhibition and may represent a therapeutic target. We conducted a multicenter, randomized, double blind, phase II/III trial of dalotuzumab, an anti-IGF-1R monoclonal antibody, with standard therapy in chemo-refractory, KRAS wild-type metastatic colorectal cancer.

Methods Eligible patients were randomly assigned to dalotuzumab 10mg/kg weekly (arm A), dalotuzumab 7.5mg/kg every alternate week (arm B), or placebo (arm C) in combination with cetuximab and irinotecan. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Secondary endpoints included exploratory biomarker analyses. All statistical tests were two-sided.

Results The trial was prematurely discontinued for futility after 344 eligible KRAS wild-type patients were included in the primary efficacy population (arm A = 116, arm B = 117, arm C = 111). Median PFS was 3.9 months in arm A (hazard ratio [HR] = 1.33, 95% confidence interval [CI] = 0.98 to 1.83, P = .07) and 5.4 months in arm B (HR = 1.13, 95% CI = 0.83 to 1.55, P = .44) compared with 5.6 months in arm C. Median OS was 10.8 months in arm A (HR = 1.41, 95% CI = 0.99 to 2.00, P = .06) and 11.6 months in arm B (HR = 1.26, 95% CI = 0.89 to 1.79, P = .18) compared with 14.0 months in arm C. Grade 3 or higher asthenia and hyperglycaemia occurred more frequently with dalotuzumab compared with placebo. In exploratory biomarker analyses, patients with high IGF-1 mRNA tumors in arm A had numerically better PFS (5.6 vs 3.6 months, HR = 0.59, 95% CI = 0.28 to 1.23, P = .16) and OS (17.9 vs 9.4 months, HR = 0.67, 95% CI = 0.31 to 1.45, P = .31) compared with those with high IGF-1 mRNA tumors in arm C. In contrast, in arm C high IGF-1 mRNA expression predicted lower response rate (17.6% vs 37.3%, P = .04), shorter PFS (3.6 vs 6.6 months, HR = 2.15, 95% CI = 1.15 to 4.02, P = .02), and shorter OS (9.4 vs 15.5 months, HR = 2.42, 95% CI = 1.21 to 4.82, P = .01).

Conclusions Adding dalotuzumab to irinotecan and cetuximab was feasible but did not improve survival outcome. IGF-1R ligands are promising biomarkers for differential response to anti-EGFR and anti-IGF-1R therapies.

First-in-Man Dose-Escalation Study of the Selective BRAF Inhibitor RG7256 in Patients with BRAF V600-Mutated Advanced Solid Tumors.

Dienstmann R, Lassen U, Cebon J, Desai J, Brown MP, Evers S, Su F, Zhang W, Boisserie F, Lestini B, Schostack K, Meresse V, Tabernero J.

Target Oncol. 2015 Aug 27. [Epub ahead of print]

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BRAF mutations are a validated target for cancer therapy. A second-generation BRAF inhibitor with an improved preclinical safety profile (RG7256) was evaluated in a first-in-man study in order to determine the safety, efficacy, pharmacokinetics and pharmacodynamics in patients with BRAF V600-mutated advanced solid tumors.

PATIENTS AND METHODS: Patients received RG7256 orally over 8 dose levels from 200 mg once a day (QD) to 2400 mg twice a day (BID) (50-, 100- and 150-mg tablets) using a classic 3 + 3 dose escalation design.

RESULTS: In total, 45 patients were enrolled; most (87 %) had advanced melanoma (94 % BRAF V600E). RG7256 was rapidly absorbed, with limited accumulation and dose-proportional increase in exposure up to 1950 mg BID. The maximal tolerated dose (MTD) was not reached. The most common drug-related adverse events (AEs) were dyspepsia (20 %), dry skin (18 %), rash (18 %), fatigue (16 %) and nausea (13 %), mainly grade 1. Three patients (7 %) developed cutaneous squamous cell carcinoma. Photosensitivity, arthralgia and increased liver enzyme levels were each observed in only one patient each. Of 44 evaluable patients, 14 (32 %) had a partial response (melanoma and thyroid cancer). At high dose levels (>1200 mg BID), 10 of 16 (63 %) patients had a partial response. A decrease in maximum standardized uptake value (SUVmax) on FDG-PET of ≥25 % was observed in 19 of 37 patients. On-treatment reductions in pERK were documented in eight of ten paired tumor samples.

CONCLUSIONS: RG7256 has a favorable safety profile compared to other BRAF inhibitors while maintaining clinical activity, and MTD was not reached. The excessive pill burden needed to provide the desired exposure, and thus concerns about patient compliance, limited further development of this agent. Study Identifier: ClinicalTrials.gov (NCT01143753).

Analysis of circulating DNA and protein biomarkers to predict the clinical activity of regorafenib and assess prognosis in patients with metastatic colorectal cancer: a retrospective, exploratory analysis of the CORRECT trial.

Tabernero J, et al.

Lancet Oncol. 2015 Aug;16(8):937-48.

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Tumour mutational status is an important determinant of the response of metastatic colorectal cancer to targeted treatments. However, the genotype of the tissue obtained at the time of diagnosis might not accurately represent tumour genotype after multiple lines of treatment. This retrospective exploratory analysis investigated the clinical activity of regorafenib in biomarker subgroups of the CORRECT study population defined by tumour mutational status or plasma protein levels.

METHODS We used BEAMing technology to identify KRAS, PIK3CA, and BRAF mutations in DNA obtained from the plasma of 503 patients with metastatic colorectal cancer who enrolled in the CORRECT trial. We quantified total human genomic DNA isolated from plasma samples for 503 patients using a modified version of human long interspersed nuclear element-1 (LINE-1) quantitive real-time PCR. We also measured the concentration of 15 proteins of interest-angiopoietin 2, interleukin 6, interleukin 8, placental growth factor, soluble TIE-1, soluble VEGFR1, VEGF-A, VEGF-C, VEGF-D, VEGF-A isoform 121, bone morphogenetic protein 7, macrophage colony-stimulating factor, stromal cell-derived factor-1, tissue inhibitor of metalloproteinase 2, and von Willebrand factor-in plasma samples from 611 patients. We did correlative analyses of overall survival and progression-free survival in patient subgroups based on mutational status, circulating DNA concentration, and protein concentrations. The CORRECT trial was registered with ClinicalTrials.gov, number NCT01103323.

INTERPRETATION BEAMing of circulating DNA could be a viable approach for non-invasive analysis of tumour genotype in real time and for the identification of potentially clinically relevant mutations that are not detected in archival tissue. Additionally, the results show that regorafenib seems to be consistently associated with a clinical benefit in a range of patient subgroups based on mutational status and protein biomarker concentrations.

OXFORD

Phase I expansion and pharmacodynamic study of the oral MEK inhibitor RO4987655 (CH4987655) in selected patients with advanced cancer with RAS-RAF mutations

Zimmer L, Barlesi F, Martinez-Garcia M, Dieras V, Schellens JH, Spano JP, Middleton MR, Calvo E, Paz-Ares 9, Larkin J, Pacey S, Venturi M, Kraeber-Bodéré F, Tessier JJ, Eberhardt WE, Paques M, Guarin E, Meresse V, Soria JC.

Clin Cancer Res. 2014 Aug 15;20(16):4251-61.

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This phase I expansion study assessed safety, pharmacodynamic effects, and antitumor activity of RO4987655, a pure MEK inhibitor, in selected patients with advanced solid tumor.

We undertook a multicenter phase I two-part study (dose escalation and cohort expansion). Here, we present the part 2 expansion that included melanoma, non-small cell lung cancer (NSCLC), and colorectal cancer with oral RO4987655 administered continuously at recommended doses of 8.5 mg twice daily until progressive disease (PD). Sequential tumor sampling investigated multiple markers of pathway activation/tumor effects, including ERK phosphorylation and Ki-67 expression. BRAF and KRAS testing were implemented as selection criteria and broader tumor mutational analysis added.

Ninety-five patients received RO4987655, including 18 BRAF-mutant melanoma, 23 BRAF wild-type melanoma, 24 KRAS-mutant NSCLC, and 30 KRAS-mutant colorectal cancer. Most frequent adverse events were rash, acneiform dermatitis, and gastrointestinal disorders, mostly grade 1/2. Four (24%) of 17 BRAF-mutated melanoma had partial response as did four (20%) of 20 BRAF wild-type melanoma and two (11%) of 18 KRAS-mutant NSCLC. All KRAS-mutant colorectal cancer developed PD. Paired tumor biopsies demonstrated reduced ERK phosphorylation among all cohorts but significant differences among cohorts in Ki-67 modulation. Sixty-nine percent showed a decrease in fluorodeoxyglucose uptake between baseline and day 15. Detailed mutational profiling confirmed RAS/RAF screening and identified additional aberrations (NRAS/non-BRAF melanomas; PIK3CA/KRAS colorectal cancer) without therapeutic implications.

Safety profile of RO4987655 was comparable with other MEK inhibitors. Single-agent activity was observed in all entities except colorectal cancer. Evidence of target modulation and early biologic activity was shown among all indications independent of mutational status. Clin Cancer Res; 20(16); 4251-61. ©2014 AACR.

UNITO

Emergence of MET hyper-amplification at progression to MET and BRAF inhibition in colorectal cancer

Oddo, D. et al.

Br. J. Cancer June 2017 (DOI: 10.1038/bjc.2017.196)

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Background: Combined MET and BRAF inhibition showed clinical benefit in a patient with rectal cancer carrying BRAFV600E and MET amplification. However, after 4 months, acquired resistance emerged and the patient deceased shortly after disease progression. The mechanism of resistance to this drug combination is unknown.

Methods: We analysed plasma circulating tumour DNA obtained at progression by exome sequencing and digital PCR. MET gene and mRNA in situ hybridisation analyses in two bioptic specimens obtained at progression were used to confirm the plasma data.

Results: We identified in plasma MET gene hyper-amplification as a potential mechanism underlying therapy resistance. Increased MET gene copy and transcript levels were detected in liver and lymph node metastatic biopsies. Finally, transduction of MET in BRAF mutant colorectal cancer cells conferred refractoriness to BRAF and MET inhibition.

Conclusions: We identified in a rectal cancer patient MET gene hyper-amplification as mechanism of resistance to dual BRAF and MET inhibition.

MET-driven resistance to dual EGFR and BRAF blockade may be overcome by switching from EGFR to MET inhibition in BRAF mutated colorectal cancer

Pietrantonio, F. et al.

Cancer Discovery June 2016 doi: 10.1158/2159-8290.CD-16-0297

Details

A patient with metastatic BRAF-mutated colorectal cancer initially responded to combined EGFR and BRAF inhibition with panitumumab plus vemurafenib. Pre-existing cells with increased MET gene copy number in the archival tumor tissue likely underwent clonal expansion during treatment, leading to the emergence of MET amplification in the re-biopsy taken at progression. In BRAF-mutated colorectal cancer cells, ectopic expression of MET conferred resistance to panitumumab and vemurafenib, which was overcome by combining BRAF and MET inhibition. Based on tumor genotyping and functional in vitro data, the patient was treated with the dual ALK-MET inhibitor crizotinib plus vemurafenib, thus switching to dual MET and BRAF blockade, with rapid and marked effectiveness of such strategy. Although acquired resistance is a major limitation to the clinical efficacy of anticancer agents, the identification of molecular targets emerging during the first treatment may afford the opportunity to design the next-line of targeted therapies, maximizing patient benefit.

Clonal evolution and resistance to EGFR blockade in the blood of colorectal cancer patients

Siravegna G, et al.

Nat Med. 2015 Jul;21(7):795-801.

Details

Colorectal cancers (CRCs) evolve by a reiterative process of genetic diversification and clonal evolution. The molecular profile of CRC is routinely assessed in surgical or bioptic samples. Genotyping of CRC tissue has inherent limitations; a tissue sample represents a single snapshot in time, and it is subjected to spatial selection bias owing to tumor heterogeneity. Repeated tissue samples are difficult to obtain and cannot be used for dynamic monitoring of disease progression and response to therapy. We exploited circulating tumor DNA (ctDNA) to genotype colorectal tumors and track clonal evolution during treatment with the epidermal growth factor receptor (EGFR)-specific antibodies cetuximab or panitumumab. We identified alterations in ctDNA of patients with primary or acquired resistance to EGFR blockade in the following genes: KRAS, NRAS, MET, ERBB2, FLT3, EGFR and MAP2K1. Mutated KRAS clones, which emerge in blood during EGFR blockade, decline upon withdrawal of EGFR-specific antibodies, indicating that clonal evolution continues beyond clinical progression. Pharmacogenomic analysis of CRC cells that had acquired resistance to cetuximab reveals that upon antibody withdrawal KRAS clones decay, whereas the population regains drug sensitivity. ctDNA profiles of individuals who benefit from multiple challenges with anti-EGFR antibodies exhibit pulsatile levels of mutant KRAS. These results indicate that the CRC genome adapts dynamically to intermittent drug schedules and provide a molecular explanation for the efficacy of rechallenge therapies based on EGFR blockade.

Molecular heterogeneity and receptor co-amplification drive resistance to targeted therapy in MET-amplified esophagogastric cancer

Kwak EL, Ahronian LG, Siravegna G, Mussolin B, Godfrey JT, Clark JW, Blaszkowsky LS, Ryan DP, Lennerz JK, Iafrate AJ, Bardelli A, Hong TS, Corcoran RB.

Cancer Discov. 2015 Oct 2. [Epub ahead of print]

Details

MET inhibition is effective in some MET-amplified esophagogastric cancer (EGC) patients, but understanding acquired and de novo resistance mechanisms will be critical to improving therapy. We identified KRAS mutation as a novel cause of acquired resistance in a patient after a two-year response to MET inhibitor. We also observed that 40-50% of MET-amplified EGC patients harbor co-amplification of HER2 and/or EGFR concurrently in the same tumor cells, which can drive de novo resistance. One patient with concurrent MET and HER2-amplification was refractory to HER2 blockade, but responded to combined MET/HER2 inhibition. We also found striking heterogeneity in MET-amplification between distinct metastatic lesions and primary tumors in individual EGC patients. In these patients, MET inhibition led to mixed responses and disease progression through outgrowth of non-MET-amplified clones, which could be monitored in circulating tumor DNA. Thus, receptor co-amplification and molecular heterogeneity may be key drivers of clinical resistance in MET-amplified EGC.

Vertical suppression of the EGFR pathway prevents onset of resistance in colorectal cancers

Misale S, Bozic I, Tong J, Peraza-Penton A, Lallo A, Baldi F, Lin KH, Truini M, Trusolino L, Bertotti A, Di Nicolantonio F, Nowak MA, Zhang L, Wood KC, Bardelli A.

Nat Commun. 2015 Sep 22;6:8305

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Molecular targeted drugs are clinically effective anti-cancer therapies. However, tumours treated with single agents usually develop resistance. Here we use colorectal cancer (CRC) as a model to study how the acquisition of resistance to EGFR-targeted therapies can be restrained. Pathway-oriented genetic screens reveal that CRC cells escape from EGFR blockade by downstream activation of RAS-MEK signalling. Following treatment of CRC cells with anti-EGFR, anti-MEK or the combination of the two drugs, we find that EGFR blockade alone triggers acquired resistance in weeks, while combinatorial treatment does not induce resistance. In patient-derived xenografts, EGFR-MEK combination prevents the development of resistance. We employ mathematical modelling to provide a quantitative understanding of the dynamics of response and resistance to these single and combination therapies. Mechanistically, we find that the EGFR-MEK Combo blockade triggers Bcl-2 and Mcl-1 downregulation and initiates apoptosis. These results provide the rationale for clinical trials aimed at preventing rather than intercepting resistance.

The molecular landscape of colorectal cancer cell lines unveils clinically actionable kinase targets

Medico E, Russo M, Picco G, Cancelliere C, Valtorta E, Corti G, Buscarino M, Isella C, Lamba S, Martinoglio B, Veronese S, Siena S, Sartore-Bianchi A, Beccuti M, Mottolese M, Linnebacher M, Cordero F, Di Nicolantonio F, Bardelli A.

Nat Commun. 2015 Apr 30;6:7002.

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The development of molecularly targeted anticancer agents relies on large panels of tumour-specific preclinical models closely recapitulating the molecular heterogeneity observed in patients. Here we describe the mutational and gene expression analyses of 151 colorectal cancer (CRC) cell lines. We find that the whole spectrum of CRC molecular and transcriptional subtypes, previously defined in patients, is represented in this cell line compendium. Transcriptional outlier analysis identifies RAS/BRAF wild-type cells, resistant to EGFR blockade, functionally and pharmacologically addicted to kinase genes including ALK, FGFR2, NTRK1/2 and RET. The same genes are present as expression outliers in CRC patient samples. Genomic rearrangements (translocations) involving the ALK and NTRK1 genes are associated with the overexpression of the corresponding proteins in CRC specimens. The approach described here can be used to pinpoint CRCs with exquisite dependencies to individual kinases for which clinically approved drugs are already available.

UZA

Analysis of KRAS/NRAS Mutations in a Phase 3 Study of Panitumumab With FOLFIRI Compared With FOLFIRI Alone as Second-Line Treatment for Metastatic Colorectal Cancer

Peeters M, et al.

Clin Cancer Res. 2015 Sep 4. [Epub ahead of print]

Details

We evaluated the influence of RAS mutation status on the treatment effect of panitumumab in a prospective-retrospective analysis of a randomized, multicenter phase 3 study of panitumumab plus fluorouracil, leucovorin, and irinotecan (FOLFIRI) versus FOLFIRI alone as second-line therapy in patients with metastatic colorectal cancer (mCRC; ClinicalTrials.gov, NCT0039183).

EXPERIMENTAL DESIGN Outcomes were from the study’s primary analysis. RAS mutations beyond KRAS exon 2 (KRAS exons 3, 4; NRAS exons 2, 3, 4; BRAF exon 15) were detected by bidirectional Sanger sequencing in wild-type KRAS exon 2 tumor specimens. Progression-free survival (PFS) and overall survival (OS) were coprimary endpoints.

RESULTS The RAS ascertainment rate was 85%; 18% of wild-type KRAS exon 2 tumors harbored other RAS mutations. For PFS and OS, the hazard ratio for panitumumab plus FOLFIRI versus FOLFIRI alone more strongly favored panitumumab in the wild-type RAS population than in the wild-type KRAS exon 2 population (PFS HR, 0.70 [95%CI=0.54‒0.91];P=0.007 versus 0.73 [95%CI=0.59-0.90];P=0.004; OS HR, 0.81 [95%CI=0.63‒1.03];P=0.08 versus 0.85 [95%CI=0.70‒1.04];P=0.12). Patients with RAS mutations were unlikely to benefit from panitumumab. Among RAS wild-type patients, the objective response rate was 41% in the panitumumab-FOLFIRI group versus 10% in the FOLFIRI group.

CONCLUSIONS Patients with RAS mutations were unlikely to benefit from panitumumab-FOLFIRI and the benefit-risk of panitumumab-FOLFIRI was improved in the wild-type RAS population compared to the wild-type KRAS exon 2 population. These findings support RAS testing for patients with mCRC.

Randomized trial of TAS-102 for refractory metastatic colorectal cancer

Mayer RJ, Van Cutsem E, Falcone A, Yoshino T, Garcia-Carbonero R, Mizunuma N, Yamazaki K, Shimada Y, Tabernero J, Komatsu Y, Sobrero A, Boucher E, Peeters M, Tran B, Lenz HJ, Zaniboni A, Hochster H, Cleary JM, Prenen H, Benedetti F, Mizuguchi H, Makris L, Ito M, Ohtsu A; RECOURSE Study Group.

N Engl J Med. 2015 May 14;372(20):1909-19.

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Early clinical trials conducted primarily in Japan have shown that TAS-102, an oral agent that combines trifluridine and tipiracil hydrochloride, was effective in the treatment of refractory colorectal cancer. We conducted a phase 3 trial to further assess the efficacy and safety of TAS-102 in a global population of such patients.

METHODS In this double-blind study, we randomly assigned 800 patients, in a 2:1 ratio, to receive TAS-102 or placebo. The primary end point was overall survival.

RESULTS The median overall survival improved from 5.3 months with placebo to 7.1 months with TAS-102, and the hazard ratio for death in the TAS-102 group versus the placebo group was 0.68 (95% confidence interval [CI], 0.58 to 0.81; P<0.001). The most frequently observed clinically significant adverse events associated with TAS-102 were neutropenia, which occurred in 38% of those treated, and leukopenia, which occurred in 21%; 4% of the patients who received TAS-102 had febrile neutropenia, and one death related to TAS-102 was reported. The median time to worsening performance status (a change in Eastern Cooperative Oncology Group performance status [on a scale of 0 to 5, with 0 indicating no symptoms and higher numbers indicating increasing degrees of disability] from 0 or 1 to 2 or more) was 5.7 months with TAS-102 versus 4.0 months with placebo (hazard ratio, 0.66; 95% CI, 0.56 to 0.78; P<0.001). CONCLUSIONS In patients with refractory colorectal cancer, TAS-102, as compared with placebo, was associated with a significant improvement in overall survival.

cMET in NSCLC: Can We Cut off the Head of the Hydra? From the Pathway to the Resistance

Van Der Steen N, Pauwels P, Gil-Bazo I, Castañon E, Raez L, Cappuzzo F, Rolfo C.

Cancers (Basel). 2015 Mar 25;7(2):556-73.

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In the last decade, the tyrosine kinase receptor cMET, together with its ligand hepatocyte growth factor (HGF), has become a target in non-small cell lung cancer (NSCLC). Signalization via cMET stimulates several oncological processes amongst which are cell motility, invasion and metastasis. It also confers resistance against several currently used targeted therapies, e.g., epidermal growth factor receptor (EGFR) inhibitors. In this review, we will discuss the basic structure of cMET and the most important signaling pathways. We will also look into aberrations in the signaling and the effects thereof in cancer growth, with the focus on NSCLC. Finally, we will discuss the role of cMET as resistance mechanism.

VCC

Epidermal growth factor receptor immunohistochemistry: new opportunities in metastatic colorectal cancer

Hutchinson RA, Adams RA, McArt DG, Salto-Tellez M, Jasani B, Hamilton PW.

J Transl Med. 2015 Jul 7;13:217.

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The treatment of cancer is becoming more precise, targeting specific oncogenic drivers with targeted molecular therapies. The epidermal growth factor receptor has been found to be over-expressed in a multitude of solid tumours. Immunohistochemistry is widely used in the fields of diagnostic and personalised medicine to localise and visualise disease specific proteins. To date the clinical utility of epidermal growth factor receptor immunohistochemistry in determining monoclonal antibody efficacy has remained somewhat inconclusive. The lack of an agreed reproducible scoring criteria for epidermal growth factor receptor immunohistochemistry has, in various clinical trials yielded conflicting results as to the use of epidermal growth factor receptor immunohistochemistry assay as a companion diagnostic. This has resulted in this test being removed from the licence for the drug panitumumab and not performed in clinical practice for cetuximab. In this review we explore the reasons behind this with a particular emphasis on colorectal cancer, and to suggest a way of resolving the situation through improving the precision of epidermal growth factor receptor immunohistochemistry with quantitative image analysis of digitised images complemented with companion molecular morphological techniques such as in situ hybridisation and section based gene mutation analysis.