Marta Caporale

MET-Driven Resistance to Dual EGFR and BRAF Blockade May Be Overcome by Switching from EGFR to MET Inhibition in BRAF-Mutated Colorectal Cancer

UNLABELLED 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 rebiopsy 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. SIGNIFICANCE MET amplification is here identified-clinically and preclinically-as a new mechanism of resistance to EGFR and BRAF dual/triple block combinations in BRAF-mutated colorectal cancer. Switching from EGFR to MET inhibition, while maintaining BRAF inhibition, resulted in clinical benefit after the occurrence of MET-driven acquired resistance. Cancer Discov; 6(9); 963-71. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 932.

Location of Primary Tumor and Benefit From Anti-Epidermal Growth Factor Receptor Monoclonal Antibodies in Patients With RAS and BRAF Wild-Type Metastatic Colorectal Cancer

INTRODUCTION Right- and left-sided colorectal cancers (CRCs) differ in clinical and molecular characteristics. Some retrospective analyses suggested that patients with right-sided tumors derive less benefit from anti-epidermal growth factor receptor (EGFR) antibodies; however, molecular selection in those studies was not extensive. PATIENTS AND METHODS Patients with RAS and BRAF wild-type metastatic CRC (mCRC) who were treated with single-agent anti-EGFRs or with cetuximab-irinotecan (if refractory to previous irinotecan) were included in the study. Differences in outcome between patients with right- and left-sided tumors were investigated. RESULTS Of 75 patients, 14 and 61 had right- and left-sided tumors, respectively. None of the right-sided tumors responded according to RECIST, compared with 24 left-sided tumors (overall response rate: 0% vs. 41%; p = .0032), and only 2 patients with right-sided tumors (15%) versus 47 patients with left-sided tumors (80%) achieved disease control (p < .0001). The median duration of progression-free survival was 2.3 and 6.6 months in patients with right-sided and left-sided tumors, respectively (hazard ratio: 3.97; 95% confidence interval: 2.09-7.53; p < .0001). CONCLUSION Patients with right-sided RAS and BRAF wild-type mCRC seemed to derive no benefit from single-agent anti-EGFRs. IMPLICATIONS FOR PRACTICE Right- and left-sided colorectal tumors have peculiar epidemiological and clinicopathological characteristics, distinct gene expression profiles and genetic alterations, and different prognoses. This study assessed the potential predictive impact of primary tumor site with regard to anti-epidermal growth factor receptor (EGFR) monoclonal antibody treatment in patients with RAS and BRAF wild-type metastatic colorectal cancer. The results demonstrated the lack of activity of anti-EGFRs in RAS and BRAF wild-type, right-sided tumors, thus suggesting a potential role for primary tumor location in driving treatment choices.

HER2 loss in HER2-positive gastric or gastroesophageal cancer after trastuzumab therapy : Implication for further clinical research

Mechanisms of acquired resistance to trastuzumab‐based treatment in gastric cancer are largely unknown. In this study, we analyzed 22 pairs of tumor samples taken at baseline and post‐progression in patients receiving chemotherapy and trastuzumab for advanced HER2‐positive [immunohistochemistry (IHC) 3+ or 2+ with in‐situ hybridization (ISH) amplification] gastric or gastroesophageal cancers. Strict clinical criteria for defining acquired trastuzumab resistance were adopted. Loss of HER2 positivity and loss of HER2 over‐expression were defined as post‐trastuzumab IHC score <3+ and absence of ISH amplification, and IHC “downscoring” from 2+/3+ to 0/1+, respectively. HER2 IHC was always performed, while ISH was missing in 3 post‐progression samples. Patients with initial HER2 IHC score 3+ and 2+ were 14 (64%) and 8 (36%), respectively. Loss of HER2 positivity and HER2 over‐expression was observed in 32 and 32% samples, respectively. The chance of HER2 loss was not associated with any of the baseline clinicopathological variables. The only exception was in patients with initial IHC score 2+ versus 3+, for both endpoints of HER2 positivity (80 vs. 14%; p = 0.008) and HER2 over‐expression (63 vs. 14%; p = 0.025). As already shown in breast cancer, loss of HER2 may be observed also in gastric cancers patients treated with trastuzumab‐based chemotherapy in the clinical practice. This phenomenon may be one of the biological reasons explaining the failure of anti‐HER2 second‐line strategies in initially HER2‐positive disease.

Undetected toxicity risk in pharmacogenetic testing for dihydropyrimidine dehydrogenase.

Fluoropyrimidines, the mainstay agents for the treatment of colorectal cancer, alone or as a part of combination therapies, cause severe adverse reactions in about 10%–30% of patients. Dihydropyrimidine dehydrogenase (DPD), a key enzyme in the catabolism of 5-fluorouracil, has been intensively investigated in relation to fluoropyrimidine toxicity, and several DPD gene (DPYD) polymorphisms are associated with decreased enzyme activity and increased risk of fluoropyrimidine-related toxicity. In patients carrying non-functional DPYD variants (c.1905+1G>A, c.1679T>G, c.2846A>T), fluoropyrimidines should be avoided or reduced according to the patients’ homozygous or heterozygous status, respectively. For other common DPYD variants (c.496A>G, c.1129-5923C>G, c.1896T>C), conflicting data are reported and their use in clinical practice still needs to be validated. The high frequency of DPYD polymorphism and the lack of large prospective trials may explain differences in studies’ results. The epigenetic regulation of DPD expression has been recently investigated to explain the variable activity of the enzyme. DPYD promoter methylation and its regulation by microRNAs may affect the toxicity risk of fluoropyrimidines. The studies we reviewed indicate that pharmacogenetic testing is promising to direct personalised dosing of fluoropyrimidines, although further investigations are needed to establish the role of DPD in severe toxicity in patients treated for colorectal cancer.

Prognostic value of diffuse versus intestinal histotype in patients with gastric cancer: a systematic review and meta-analysis

BACKGROUND There are two distinct types of gastric carcinoma (GC), intestinal, more frequently sporadic and linked to environmental factors, and diffuse (undifferentiated) that is highly metastatic and characterized by rapid disease progression and a poor prognosis. However, there are many conflicting data in the literature concerning the association between histology and prognosis in GC. This meta-analysis was performed to provide demonstration if histology according to Lauren classification is associated with different prognosis in patients with GC. METHODS We searched PubMed, the Cochrane Library, SCOPUS, Web of Science, CINAHL, and EMBASE for all eligible studies. The combined hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) in terms of overall survival (OS) were evaluated. RESULTS A total of 73 published studies including 61,468 patients with GC were included in this meta-analysis. Our analysis indicates that GC patients with diffuse-type histology have a worst prognosis than those with intestinal subgroup in all studies (HR 1.23; 95% CI, 1.17-1.29; P<0.0001), in both loco-regional confined (HR 1.21; 95% CI, 1.12-1.30; P<0.0001) and advanced disease (HR 1.25; 95% CI, 1.046-1.50; P=0.014), in Asiatic (HR 1.2; 95% CI, 1.14-1.27; P<0.0001) and Western patients (HR 1.3; 95% CI, 1.19-1.41; P<0.0001), and in those not exposed (HR 1.15; 95% CI, 1.07-1.24; P<0.0001) or exposed (HR 1.27; 95% CI, 1.17-1.37; P<0.0001) to (neo)adjuvant therapy. CONCLUSIONS Our results indicated that histology might be a useful prognostic marker for both early and advanced GC patients, with intestinal-type associated with a better outcome. This information could be used for stratification purpose in future clinical trials.

BRAF in metastatic colorectal cancer: the future starts now

BRAF mutations are detectable in about 5-15% of metastatic colorectal cancer (mCRC) patients and represent a clear negative prognostic factor. While in BRAF-mutated (BRAFmt) metastatic melanoma TKI target therapies (BRAF and MEK inhibitor), both alone or in combination, have shown significant efficacy, in BRAFmt CRC single-agent BRAF-inhibitors as well as chemotherapy seem to be ineffective. The critical role of EGFR in CRC and its multiple downstreaming pathways seem to be involved in this lack of response. In recent years, preclinical investigations and retrospective studies slowly increased our knowledge on BRAFmt CRC. This review analyses preclinical data and discusses several clinical trials in order to explore new therapeutic strategies targeting BRAFmt mCRC.

IL-8 and eNOS polymorphisms predict bevacizumab-based first line treatment outcomes in RAS mutant metastatic colorectal cancer patients

Background Predictive biomarkers of efficacy and toxicity of bevacizumab have not yet been validated. This study assessed the influence of IL-8, eNOS and VEGF-A polymorphisms in RAS mutated metastatic colorectal cancer patients receiving bevacizumab-based chemotherapy. Methods 120 patients treated with first-line combination FOLFOX6 plus bevacizumab were included. A historical cohort of 112 RAS mutated colorectal cancer patients treated with FOLFOX6 alone served as control group. The following SNPs were analyzed: IL-8 c.-251T>A; eNOS c.-786T>C and c.-894G>T; VEGF-A c.936C>T, c.958T>C, c.1154A>G and c.2578C>A. Correlation of SNPs, baseline IL-8 serum levels and bevacizumab-efficacy was done. Results In the bevacizumab group, carriers of the IL-8 alleles c.-251TA+AA showed a shorter PFS (P=0.002) and OS (P=0.03) compared to TT alleles. Patients with pre-treatment IL-8 < 18.25 pg/ml showed significantly longer median PFS and OS (PFS: 10.9 vs 7.6 months, P=0.005; OS: 30.7 vs 18.2 months, P<0.001) compared to patients with IL-8 higher levels (>18,25 pg/ml). IL-8 c.-251TA+AA carriers had significantly higher IL-8 levels (P<0.0001). Multivariate analysis confirmed association of IL-8 polymorphism with PFS, and of IL-8 baseline levels with both PFS and OS. IL-8 SNP did not affect the outcome in the control group. The eNOS polymorphism c.-894G>T was found associated with higher severe toxicity (P=0.0002) in patients carrying the c.-894TT genotype. Conclusions Although our data need prospective validation, IL-8 and eNOS SNPs may be have a role as predictive biomarkers for bevacizumab efficacy and toxicity.

Perioperative Triplet Chemotherapy and Cetuximab in Patients With RAS Wild Type High Recurrence Risk or Borderline Resectable Colorectal Cancer Liver Metastases

Background: For borderline resectable colorectal cancer liver metastases (CLM), systemic treatment can help to achieve R0 resection and reduce the risk of relapse. We assessed the role of perioperative triplet chemotherapy in combination with cetuximab in patients with RAS wild type high recurrence risk and/or borderline resectable CLM. Patients and Methods: This was a monocenter, open‐label phase II study. Borderline resectability was defined technically as tumor involvement of >1 hepatic vein, or >4 hepatic segments, need for 2‐stage hepatectomy or radiofrequency ablation, and/or biologically (high risk): ≥4 metastatic nodules, or synchronous metastases. Patients were treated with 4 pre‐ and postoperative cycles of biweekly COI‐E (cetuximab 500 mg/m2 and irinotecan 180 mg/m2 on day 1, oxaliplatin 85 mg/m2 on day 2, and capecitabine 1000 mg/m2 twice per day on days 2‐6). The primary end point was overall response rate. Results: Forty patients were enrolled. Nine patients with KRAS mutation were excluded after amendment in 2010. In an extended RAS test we did not find additional RAS mutations. The final population was comprised of 31 patients with RAS wild type CLM (technically borderline resectable 39%; synchronous 84%; ≥4 metastatic nodules 29%). The overall response, R0 resection, and pathological response rates were 87%, 84%, and 33%, respectively. At a median follow‐up of 4 years, median progression‐free survival and overall survival were 17.8 and 62.5 months, respectively. Treatment toxicity was relevant but did not jeopardize the surgical plan. Conclusion: The COI‐E regimen was associated with high response and R0 resection rates in patients with RAS wild type CLM with borderline resectability and/or high‐risk features. &NA; In this phase II trial we aimed to evaluate the activity and safety of early resection with perioperative triplet chemotherapy in combination with cetuximab in 31 patients with high recurrence risk and/or borderline resectable RAS wild type colorectal cancer liver metastases. The results showed a high response rate (87%), depth of response (−51%), and R0 resection (83%), with manageable toxicity. Perioperative triplet chemotherapy in combination with cetuximab was a feasible strategy in this setting and should be further evaluated for unresectable or technically borderline resectable RAS and BRAF wild type colorectal cancer.

Second-line angiogenesis inhibition in metastatic colorectal cancer patients: Straightforward or overcrowded?

Although the number of therapeutic options targeting tumour angiogenesis is becoming increasingly relevant, the question of the optimal choice for second-line anti-angiogenic inhibition in combination with chemotherapy for metastatic colorectal cancer patients remains largely unanswered. In fact the lack of head to head comparison between consolidated options such as bevacizumab and new treatment alternatives such as aflibercept and ramucirumab makes the selection in the clinical practice challenging, particularly when the patient has already received an anti-angiogenic-based combination up-front. In the following pages we described the biological scenario validating second-line angiogenesis inhibition in colorectal cancer along with potential mechanism of resistance. We also critically described the available evidence recommending the use of the bevacizumab, aflibercept and ramucirumab in this setting with the final aim to guide the choice in the clinical practice.

Variant alleles in factor V, prothrombin, plasminogen activator inhibitor-1, methylenetetrahydrofolate reductase and risk of thromboembolism in metastatic colorectal cancer patients treated with first-line chemotherapy plus bevacizumab

Single-nucleotide polymorphisms (SNPs) related to hereditary thrombophilia were investigated as risk factors for thromboembolism in cancer patients. Their effect in metastatic colorectal cancer (mCRC) has never been explored so far. Our aim was to analyse the effect of coagulation factor V (FVL G1691A), prothrombin (PT G20210A), methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and plasminogen activator inhibitor type 1 (PAI-1 5G/4G) allelic variants in this setting. Fifty-two patients treated with first-line chemotherapy plus bevacizumab who developed a thromboembolic event in their lifetime were initially genotyped. A contemporary cohort of 127 patients who did not experience any thromboembolic event was also analysed. DNA was extracted from peripheral blood and genotypes were determined by real-time PCR, using LightSNiP (TIB MOLBIOL) on LightCcler 480 (Roche). The association between thromboembolism and SNPs was investigated by univariable and multivariable analyses. All SNPs were in Hardy–Weinberg equilibrium (χ2 test P>0.20). FVL G1691A and PT G20210A were present only in heterozygosis in 4 (2.2%) and 7 (3.9%) patients, respectively; MTHFR C677T in homozygosis in 29 (16.2%), MTHFR A1298C in homozygosis in 13 (7.3%); PAI-1 5G/4G in 98 (54.7%) and 4G/4G in 41 (23%) patients. At univariable analysis, treatment duration was significantly associated with thromboembolism (P<0.001), whereas gender, age, obesity, platelets count and chemotherapy backbone were not. Similarly, FVL G1691A and PT G20210A as well as MTHFR C677T and PAI-1 4G allele were significantly associated, whereas MTHFR A1298C was not. At multivariable model including PT G20210A, MTHFR C677T and PAI-1 4G (age, obesity, treatment duration and chemotherapy backbone were included as adjustment factors), the three SNPs were significantlty associated with higher risk of thromboembolism (P=0.025, <0.0001 and P=0.033, respectively). Further validation studies are warranted in order to design a prospective trial of thromboprophylaxis in mCRC patients with high-risk genotypes.