RAS Wild-type mCRC Research Articles

Biologic Response of Colorectal Cancer Xenograft Tumors to Sequential Treatment with Panitumumab and Bevacizumab

Recent studies in RAS wild-type (WT) metastatic colorectal cancer (mCRC) suggest that the survival benefits of therapy using anti-epidermal growth factor receptor (anti-EGFR) and anti-vascular endothelial growth factor (anti-VEGF) antibodies combined with chemotherapy are maximized when the anti-EGFR antibody is given as first-line, followed by subsequent anti-VEGF antibody therapy. We report reverse-translational research using LIM1215 xenografts of RAS WT mCRC to elucidate the biologic mechanisms underlying this clinical observation. Sequential administration of panitumumab then bevacizumab (PB) demonstrated a stronger tendency to inhibit tumor growth than bevacizumab then panitumumab (BP). Cell proliferation was reduced significantly with PB (P < .01) but not with BP based on Ki-67 index. Phosphoproteomic analysis demonstrated reduced phosphorylation of EGFR and EPHA2 with PB and BP compared with control. Western blotting showed reduced EPHA2 expression and S897-phosphorylation with PB; RSK phosphorylation was largely unaffected by PB but increased significantly with BP. In quantitative real-time PCR analyses, PB significantly reduced the expression of both lipogenic (FASN, MVD) and hypoxia-related (CA9, TGFBI) genes versus control. These results suggest that numerous mechanisms at the levels of gene expression, protein expression, and protein phosphorylation may explain the improved clinical activity of PB over BP in patients with RAS WT mCRC.

Colorectal Cancer: Why Does Side Matter?

Colorectal cancer (CRC) is a heterogeneous disease, and the search for clinical and molecular prognostic and predictive factors is thus necessary to better tailor each individual patient's management. Primary tumor location (PTL) seems to act as a master prognostic factor pooling different clinical, pathological, and molecular poor prognostic factors. In fact, right-sided (RS) CRC patients are more frequently femaleand elderly with microsatellite unstable, BRAF mutated, CpG island methylator phenotype (CIMP)-high, poorly differentiated tumors, compared to left-sided (LS) CRC patients. PTL does not seem to clearly influence disease-free survival (DFS) in localised colon cancer even though the opposite prognostic value of RS tumors on DFS depending on RAS/BRAF mutational status has been recently suggested in these patients. In metastatic CRC (mCRC), the poor prognosis associated with RS tumors is confirmed in the most recent publications in the era of double and triple chemotherapeutic regimens and targeted agents. Concerning the predictive value of PTL, in patients with RAS wild-type mCRC in the first-line setting, anti-epidermal growth factor receptor (EGFR) therapy combined with chemotherapy appears to be more effective than bevacizumab in LS CRC, while patients with RS CRC benefit less from anti-EGFR therapy, and intensive chemotherapy plus bevacizumab may be more appropriate but EGFR antibodies remain an option if objective response is needed. Due to the limitation of the current data (unplanned and retrospective analyses), these conclusions must be interpreted with caution. Clinical trials in RS CRC may be of interest to clarify what is the best treatment strategy in these patients.

Final Analysis of Outcomes and RAS/BRAF Status in a Randomized Phase 3 Study of Panitumumab and Best Supportive Care in Chemorefractory Wild Type KRAS Metastatic Colorectal Cancer

IntroductionTumor rat sarcoma gene (RAS) status is a negative predictive biomarker for anti-epidermal growth factor receptor (EGFR) therapy in metastatic colorectal cancer (mCRC). We analyzed outcomes according to RAS and v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutational status, and evaluated early tumor shrinkage (ETS) and depth of response (DpR) for patients with wild type RAS. Patients and MethodsPatients with confirmed metastatic colon or rectum adenocarcinoma, wild type Kristen rat sarcoma gene tumor exon 2 status, clinical/radiologic disease progression or toxicity during irinotecan or oxaliplatin treatment, and no previous anti-EGFR therapy were randomized 1:1 to receive best supportive care (BSC) with or without panitumumab (6.0 mg/kg, intravenously, on day 1 of each 14-day cycle) in this open-label, multicenter, phase III study (20100007). RAS and BRAF mutation status were determined using Sanger sequencing. ETS was evaluated as maximum percentage change from baseline to week 8; DpR was calculated as the percentage change for tumor shrinkage at nadir versus baseline. ResultsOverall, 270 patients had RAS wild type mCRC (panitumumab with BSC, n = 142; BSC, n = 128). For patients with wild type RAS tumors, median overall survival (OS; hazard ratio [HR], 0.72; P = .015) and progression-free survival (PFS; HR, 0.45; P < .0001) were improved with panitumumab with BSC versus BSC. Similar improvements were seen for patients with wild type RAS, and wild type BRAF tumors (OS: HR, 0.75; P = .04; PFS: HR, 0.45; P < .0001). Median DpR was 16.9% for the evaluable panitumumab with BSC wild type RAS population. Overall, 69.5% experienced any type of tumor shrinkage at week 8; 38.2% experienced ≥ 20% shrinkage. Similar improvements in OS and PFS were seen with stratification according to ETS. ConclusionThis analysis showed that panitumumab improved outcomes in wild type RAS mCRC and indicated that ETS and DpR could be used as additional efficacy markers.

The best strategy for RAS wild-type metastatic colorectal cancer patients in first-line treatment: A classic and Bayesian meta-analysis.

At present, there is uncertainty on the best systemic treatment in first-line setting for RAS wild-type (WT) metastatic colorectal cancer (mCRC) patients. Indeed, several chemotherapy and biologics combinations showed an improvement on survival. We performed a systematic review with a pair-wise and bayesan meta-analysis to rank the best strategy for these patients. A systematic literature search through March 2017 was performed to evaluate the association between several treatment combinations and overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and toxicity rate (TR) in RAS WT mCRC patients. Data were extracted from studies and pooled using the random-effect model for pair-wise meta-analyses and bayesan model for network meta-analysis (NMA). Eight studies with a total of 2518 individuals were included in the meta-analyses. Pooled analyses for subgroups stratified by type of schedule and tumor location demonstrated that anti-EGFR + doublet had the best OS when compared to doublet ± bevacizumab (0.767; 95%CI, 0.695-0.846; P < 0.0001). This benefit is limited to LSCC when compared to a doublet-based schedule and doublet + bevacizumab (HRs, 0.692; 95%CI, 0.596-0.804; P < 0.001; 0.706; 95%CI, 0.584-0.854; P < 0.001; respectively). No significant differences are detected in PFS, whereas the cetuximab-based regimens showed the highest ORR and TR. In NMA our ranking showed the best performance for FOLFOX + panitumumab. Our study indicates that FOLFOX + panitumumab has the major probability to provide an improvement of survival with a good safety profile in patients with RAS WT mCRC with an added value from selection based on sidedness.

Effect of Primary Tumor Location on Second- or Later-line Treatment Outcomes in Patients With RAS Wild-type Metastatic Colorectal Cancer and All Treatment Lines in Patients With RAS Mutations in Four Randomized Panitumumab Studies

BackgroundThe primary tumor location has a prognostic impact in metastatic colorectal cancer (mCRC). We report the results from retrospective analyses assessing the effect of tumor location on prognosis and efficacy of second- and later-line panitumumab treatment in patients with RAS wild-type (WT) mCRC and on prognosis in all lines of treatment in patients with RAS mutant (MT) mCRC. Patients and MethodsRAS WT data (n = 483) from 2 randomized phase III panitumumab trials (ClinicalTrials.gov identifiers, NCT00339183 and NCT00113763) were analyzed for treatment outcomes stratified by tumor location. The second analysis assessed the effect of tumor location in RAS MT patients (n = 1205) from 4 panitumumab studies (ClinicalTrials.gov identifiers, NCT00364013, NCT00819780, NCT00339183, and NCT00113763). Primary tumors located in the cecum to transverse colon were coded as right-sided; those located from the splenic flexure to the rectum were coded as left-sided. ResultsOf all patients, the tumor location was ascertained for 83% to 88%; 71% to 77% of patients had left-sided tumors. RAS WT patients with right-sided tumors did worse for all efficacy parameters compared with those with left-sided tumors. The patients with left-sided tumors had better outcomes with panitumumab than with the comparator treatment. Because of the low patient numbers, no conclusions could be drawn for right-sided mCRC. The prognostic effect of tumor location on survival was unclear for RAS MT patients. ConclusionThese retrospective analyses have confirmed that RAS WT right-sided mCRC is associated with a poor prognosis, regardless of the treatment. RAS WT patients with left-sided tumors benefitted from the addition of panitumumab in second or later treatment lines. Further research is warranted to determine the optimum management of right-sided mCRC and RAS MT tumors.

Phase I study of primary treatment with 5-FU, oxaliplatin, irinotecan, levofolinate, and panitumumab combination chemotherapy in patients with advanced/recurrent colorectal cancer involving the wild-type RAS gene: the JACCRO CC-14 study

BackgroundFOLFOXIRI is now regarded as the chemotherapy regimen that offers the best platform for the treatment of colorectal cancer. However, the safety and efficacy of FOLFOXIRI + panitumumab has not been demonstrated. We conducted a phase I study to determine the recommended dose of FOLFOXIRI + panitumumab as first-line treatment for RAS wild-type metastatic colorectal cancer (mCRC).MethodsPatients received combination therapy consisting of panitumumab (6 mg/kg on day 1) + FOLFOXIRI [irinotecan (CPT-11), oxaliplatin (L-OHP) 85 mg/m2, and folinate (LV) 200 mg/m2] on day 1, followed by fluorouracil (5-FU) 3200 mg/m2 infused as a 46-h continuous infusion starting on day 1) repeated every 2 weeks as first-line treatment of RAS wild-type mCRC patients. A decrease in CPT-11 dose was planned (started at level 1: CPT-11 165 mg/m2).ResultsSeven patients were enrolled, and six were assessed for safety and efficacy. Maximum tolerated dose was not reached at level 1; all patients were treated at these levels. The common Grade 3 or 4 relevant toxicities were diarrhea (50%), hypokalemia (33%) and stomatitis (33%). No treatment-related deaths occurred. Of the six patients assessed four had partial response and the two others had stable disease; hence, the response rate was 66.7% (95% confidence interval 28.9–100%) and the disease control rate was 100%. Time to protocol treatment failure was 7.2 (1.4–7.3) months.ConclusionThe FOLFOXIRI + panitumumab chemotherapy regimen was well tolerated by our patients with mCRC and showed promising anti-tumor activity. The recommended phase II dose was determined to be the same as the standard doses of this regimen used worldwide.

Activity and Safety of Cetuximab Plus Modified FOLFOXIRI Followed by Maintenance With Cetuximab or Bevacizumab for RAS and BRAF Wild-type Metastatic Colorectal Cancer

The combination of a triple-drug chemotherapy regimen with an anti-epidermal growth factor receptor (EGFR) agent as a first-line treatment of metastatic colorectal cancer (mCRC) showed promising activity along with safety concerns in single-arm phase 2 trials. The role of maintenance following chemotherapy and anti-EGFR and the optimal regimen to be adopted are not established. To evaluate the activity and safety of cetuximab plus modified FOLFOXIRI (mFOLFOXIRI) and explore the role of maintenance with cetuximab or bevacizumab in RAS and BRAF wild-type mCRC. In a prospective, noncomparative, open-label, multicenter, randomized phase 2 trial, patients aged 18 to 75 years with unresectable, previously untreated RAS and BRAF wild-type (before amendment, KRAS wild-type) mCRC were recruited from 21 oncology units in Italy from October 19, 2011, to March 1, 2015 (followed up through May 31, 2017). In total, 323 patients were screened and 143 were randomized to 2 treatment arms to receive as a first-line induction a regimen of mFOLFOXIRI plus cetuximab followed by cetuximab (arm A) or bevacizumab (arm B) until disease progression. Primary analyses were conducted in a modified intention-to-treat population. mFOLFOXIRI plus cetuximab repeated every 2 weeks for up to 8 cycles, followed by maintenance with cetuximab or bevacizumab until disease progression. The primary end point was the 10-month progression-free rate (PFR); secondary end points included progression-free and overall survival, response rate, rate of metastases resection, and adverse events. Of 143 patients randomized, 116 (81.1%) (median [interquartile range (IQR)] age, 59.5 [53-67] years; 34 [29.3%] women) had RAS and BRAF wild-type mCRC. At a median (IQR) follow-up of 44.0 (30.5-52.1) months, 10-month PFRs were 50.8% (90% CI, 39.5%-62.2%) in arm A and 40.4% (90% CI, 29.4%-52.1%) in arm B. The overall response rate was 71.6% (95% CI, 62.4%-79.5%). Main grade 3/4 adverse events were neutropenia (occurring in 36 patients [31%]), diarrhea (in 21 patients [18%]), skin toxic effects (in 18 patients [16%]), asthenia (in 11 patients [9%]), stomatitis (in 7 patients [6%]), and febrile neutropenia (in 3 patients [3%]). Although neither of the 2 arms met the primary end point, the findings indicate that a 4-month induction regimen of mFOLFOXIRI plus cetuximab is feasible and provides relevant activity results, leading to a high surgical resection rate. clinicaltrials.gov Identifier: NCT02295930.

A triplet combination with irinotecan, oxaliplatin, continuous infusion 5-fluorouracil and leucovorin (FOLFOXIRI) plus cetuximab as first-line treatment in RAS wild-type, metastatic colorectal cancer: A phase 1 dose finding study.

856 Background: The FOLFOXIRI regimen (irinotecan, oxaliplatin, 5-fluorouracil and leucovorin) improves the response rate and overall survival compared to FOLFIRI in pts with metastatic colorectal cancer (mCRC), and addition of cetuximab to chemotherapy increases efficacy in pts with RAS wild-type mCRC. We conducted a phase 1 study of FOLFOXIRI plus cetuximab to determine the maximum-tolerated dose (MTD) and recommended dose (RD) and to assess its safety and efficacy in Japanese pts with RAS wild-type mCRC. Methods: Main eligibility criteria were: histologically confirmed colorectal adenocarcinoma; KRAS and NRAS wild-type status; measurable metastatic disease according to Response Evaluation Criteria in Solid Tumors version 1.1; age 20-74 years; Eastern Cooperative Oncology Group performance status 0 or 1. Pts with UDP-glucuronosyltransferase 1A1*6/*6, *28/*28 and *6/*28 genotypes were excluded. Pts received an escalating dose of intravenous irinotecan (100, 120, and 150 mg/m2 in the dose levels 0, 1, and 2, respectively) and a fixed dose of intravenous oxaliplatin (85 mg/m2), continuous infusion 5-fluorouracil (2400 mg/m2) plus l-leucovorin (200 mg/m2), and cetuximab (an initial dose of 400 mg/m2 followed by 250 mg/m2 per week). Results: A total of 9 Japanese pts were treated (3 and 9 in the dose levels 1 and 2, respectively). No patients experienced a dose-limiting toxicity (the MTD was not reached), and the dose level 2 (irinotecan 150 mg/m2) was established as the RD. With a median 8 cycles per patient, the most common grade 3 or 4 adverse events included neutropenia (44%), paronychia (22%), and acne-like rash (11%). No febrile neutropenia and treatment-related death were observed. Among 9 pts, 1 pt had complete response, 7 pts had partial response, and 1 pt had progressive disease, for an overall response rate of 89%. As of September 24, 2017, median progression free survival was 14.0 (95% CI 7.2-20.7) months. Conclusions: The combination of cetuximab and FOLFOXIRI has shown a favorable toxicity profile and promising antitumor activity in pts with RAS wild-type mCRC. Clinical trial information: UMIN000018217.

Impact of primary tumour location (PTL) on outcomes in patients (pts) with metastatic colorectal cancer (mCRC) undergoing first-line panitumumab (Pmab) + FOLFIRI treatment .

820 Background: Prognosis in pts with mCRC is affected by PTL; PTL may also affect the activity of the epidermal growth factor receptor inhibitor Pmab (+ FOLFIRI). Methods: In this phase II, single-arm study (NCT00508404), pts received first-line Pmab+FOLFIRI Q2W until disease progression (PD); primary endpoint: objective response rate (ORR). Analyses included pts with RAS wild-type (WT) mCRC (no mutations in KRAS/ NRAS exons 2, 3 and 4). Baseline demographics/disease characteristics were summarised by PTL and the effect of PTL on outcome was analysed. Early tumour shrinkage (ETS) was defined as a ≥30% reduction in the sum of the longest diameters of measurable target lesions at week 8. Depth of response (DpR) was the maximum % change from baseline to nadir in pts with shrinkage, or the change at PD in pts with no shrinkage. DpR was positive for shrinkage, negative for growth and zero for no change. Progression-free survival (PFS) was analysed by PTL and ETS status. There was no long-term follow-up of overall survival in this study. Results: PTL could be determined in 52/69 (75%) RAS WT pts; 45/52 (87%) had left (L)-sided disease. Pts with L- vs right (R)-sided disease were more likely to have BRAF WT mCRC (91% vs 71%), an ECOG performance status of 0 (56% vs 43%) and liver+other metastases (53% vs 29%). Pts with L- vs R-sided disease had longer median (95% CI) PFS (11.2 [7.6,17.0] vs 7.2 [1.1,19.1] months) and were more likely to experience ETS ≥30% (53% vs 29%). ORR (60% vs 57%), median (95% CI) duration of response (DoR; 13.2 [9.3,47.7] vs 14.3 [3.5,17.3] months), median DpR (61% vs 60%), and resection rates (any: 13% vs 14%; R0: 7% vs 14%) were similar for L- and R-sided pts. ETS ≥30% was associated with improved PFS irrespective of PTL (HR [95% CI] vs ETS &lt; 30%: 0.53 [0.22,1.29] on L; 0.35 [0.03,3.54] on R). Conclusions: These post-hoc data are in line with larger previous studies suggesting improved ETS/PFS with Pmab treatment in RAS WT left-sided mCRC; ORR, DoR and DpR were similar regardless of PTL. No formal conclusions can be drawn regarding the activity of Pmab+FOLFIRI in right-sided mCRC due to the small pt numbers, but ETS may also predict PFS benefit in right-sided disease. Clinical trial information: NCT00508404.

Intensive first-line triplet chemotherapy plus cetuximab FIr-C/FOx-C in RAS wild-type MCRC: Preliminary phase II data and prediction of individual limiting toxicity syndromes by pharmacogenomic biomarkers.

673 Background: Intensive first line bevacizumab added to triplet, and cetuximab (CET) to doublet in RAS wild-type MCRC significantly increased outcomes. We investigated safety/activity of FIr-C/FOx-C adding CET to triplet in RAS wild-type. Methods: Phase II study according to Simon two-step design: delta 15% (p070%, p185%), power80%, α5%, β20%; projected ORR I step 14/19. FIr-C/FOx-C: 5-fluorouracil (5-FU) 12h-TFI 900 mg/m2 days (d) 1-2,8-9,15-16,22-23 associated to weekly alternating irinotecan (CPT-11) 160 mg/m2 d1,15 or oxaliplatin 80 mg/m2 d8,22; CET loading dose, then 250 mg/m2 d1,8,15,22; every 28d. Toxicity, LTS evaluated/compared by chi-square test; activity/efficacy by log-rank. Pharmacogenomic biomarkers of 5-FU/CPT-11, 5-FU degradation rate (5-FUDR), Single Nucleotide Polimorphisms (SNP) ABCB1, CYP3A4, DYPD, UGT1A1, evaluated in individual patients with limiting toxicity syndromes (LTS) and at recommended dose. Results: 29 patients &lt; 75 years, primary/intermediate CIRS. From April 2014, KRAS/NRAS wild-type eligible: median age 59; young-elderly (yE) 7, 24%; liver-limited (L-L) 7, 24%. Recommended CPT-11/5-FU doses 120/750 mg/m2. Activity met primary endpoint: OR 14/18 evaluable as-treated (76%), confirmed in preliminary phase II, 17/23 intent-to-treat (74%). Liver metastasectomies 14%, 57% L-L. At median follow-up 18 months, PFS 12, OS 23 months. At recommended doses, received DI &gt; 80% for each drug; cumulative G3-4 toxicities: diarrhea 23%, asthenia 15%, vomiting 8%, hypertransaminasemy 8%; LTS, consisting of the LT, associated or not to G2 or other LT, in 19 patients (65.5%), 83% yE. LTS prevalently multiple than single site (59 vs 7% p0.006). Reduced FUDR, CYP3A4 and UGT1A1 SNPs, frequently associated, prevalently in patients with gastrointestinal LTS, while not without LTS. Conclusions: Intensive first-line FIr-C/FOx-C at recommended dose is tolerable, highly effective in RAS wild-type. Reduced FUDR, CYP3A4, UGT1A1 SNPs may predict individual LTS to select fit patients. Prospective studies will confirm efficacy and personalization by companion toxicity biomarkers. Clinical trial information: EudraCT 2009-016793-32.

Chemotherapy plus Panitumumab Versus Chemotherapy plus Bevacizumab in Metastatic Colorectal Cancer: A Meta-analysis

Panitumumab and bevacizumab have been widely used in combination with chemotherapy for patients with wild type RAS metastatic colorectal cancer (mCRC). Whether panitumumab or bevacizumab was the optimal option remained controversial. Thus, we conducted a meta-anaylsis to evaluate chemotherapy plus panitumumab (C + P) versus chemotherapy plus bevacizumab (C + B) in wild type RAS mCRC. Electronic databases including PubMed, Embase, and Web of Science, Cochrane Library, ClinicalTrials.gov, were searched. This meta-analysis estimated the progression-free survival (PFS), overall survival (OS), overall response rate (ORR) and adverse events (AEs). Three randomized controlled trials with a total number of 577 patients were included. In wild type RAS population, PFS [hazard ratio (HR) = 0.96; 95% confidence interval (CI), 0.76 to 1.15] and OS (HR = 0.90; 95% CI, 0.54 to 1.27) and ORR [relative ratio (RR) = 2.06; 95% CI, 0.86 to 4.90] appeared similar between the two treatments, the incidence of AEs slightly increased (RR = 1.16; 95% CI 1.08 to 1.26). In conclusion, there was insufficient evidence to precisely conclude that combination treatment of C + P had an improved efficacy compared with C + B. Further large-scale and better-designed clinical trials are still needed to evaluate the combination treatment of C + P in patients with wild type RAS mCRC.

Panitumumab use in metastatic colorectal cancer and patterns of RAS testing: results from a Europe-wide physician survey and medical records review

BackgroundIn Europe, treatment of metastatic colorectal cancer (mCRC) with panitumumab requires prior confirmation of RAS wild-type mutation status. Two studies – a physician survey and a medical records review (MRR) – were conducted to evaluate the use of panitumumab and awareness among prescribing oncologists of the associated RAS testing requirements in clinical practice.MethodsBoth studies enrolled participants from nine European countries and were carried out in three consecutive rounds. Rounds 1 and 2 (2012–2013) examined KRAS (exon 2) testing only; the results have been published in full previously. Round 3 (2014–2015) examined full RAS testing (exons 2, 3, 4 of KRAS and NRAS) and was initiated following a change in prescribing guidelines, from requiring KRAS alone to requiring full RAS testing. For the physician survey, telephone interviews were conducted with oncologists who had prescribed panitumumab to patients with mCRC in the previous 6 months. For the MRR, oncologists were asked to provide anonymised clinical information, extracted from their patients’ records.ResultsIn Round 3, 152 oncologists and 131 patients’ records were included in the physician survey and MRR, respectively. In Round 3 of the physician survey, 95.4% (n = 145) of participants correctly identified that panitumumab should only be prescribed in RAS wild-type mCRC compared with 99.0% (n = 298) of 301 participants in Rounds 1 and 2, responding to the same question about KRAS testing. In Round 3 of the MRR, 100% (n = 131) of patients included in the study had confirmed KRAS or RAS wild-type status prior to initiation of panitumumab compared with 97.7% (n = 299) of 306 patients in Rounds 1 and 2 (KRAS only). Of those patients in Round 3, 83.2% (n = 109) had been tested for RAS status and 16.8% (n = 22) had been tested for KRAS status only.ConclusionsPhysicians’ adherence to prescribing guidelines has remained high over time in Europe, despite the change in indication for panitumumab treatment, from KRAS to RAS wild-type mCRC. Additionally, this study demonstrates the uptake of full RAS testing among the majority of oncologists and pathologists.

Relevance of liver‐limited disease in metastatic colorectal cancer: Subgroup findings of the FIRE‐3/AIO KRK0306 trial

In metastatic colorectal cancer (mCRC), liver-limited disease (LLD) is associated with a higher chance of metastectomy leading to long-term survival. However, limited data describes the prognostic and predictive relevance of initially unresectable LLD with regard to targeted first-line therapy. The present analysis investigated the relevance of initially unresectable LLD in mCRC patients treated with targeted therapy against either the epidermal growth factor receptor (EGFR) or vascular epithelial growth factor (VEGF). The analysis was performed based on FIRE-3, a randomized phase III trial comparing first-line chemotherapy with FOLFIRI plus either cetuximab (anti-EGFR) or bevacizumab (anti-VEGF) in RAS wild-type (WT) mCRC. Of 400 patients, 133 (33.3%) had LLD and 267 (66.8%) had non-LLD. Median overall survival (OS) was significantly longer in LLD compared to non-LLD patients (36.0 vs. 25.4 months; hazard ratio [HR] = 0.66; 95% confidence interval [CI]: 0.51-0.87; p = 0.002). In a multivariate analysis also including secondary hepatic resection as time-dependent variable, LLD status was independently prognostic for OS (HR = 0.67; 95% CI: 0.50-0.91; p = 0.01). As assessed by interaction tests, treatment benefit from FOLFIRI plus cetuximab compared to FOLFIRI plus bevacizumab was independent of LLD status with regard to objective response rate (ORR), early tumour shrinkage ≥20% (ETS), depth of response (DpR) and OS (all p > 0.05). In conclusion, LLD could be identified as a prognostic factor in RAS-WT mCRC, which was independent of hepatic resection in patients treated with targeted therapy. LLD had no predictive relevance since benefit from FOLFIRI plus cetuximab over bevacizumab was independent of LLD status.

Exploratory analyses assessing the impact of early tumour shrinkage and depth of response on survival outcomes in patients with RAS wild-type metastatic colorectal cancer receiving treatment in three randomised panitumumab trials

PurposeTo report exploratory analyses of early tumour shrinkage (ETS) and depth of response (DpR) in patients with RAS wild-type (WT) metastatic colorectal cancer (mCRC), receiving the first-line treatment in three randomised panitumumab trials.MethodsData from the PRIME (NCT00364013), PEAK (NCT00819780) and PLANET (NCT00885885) studies were included. Median DpR, the proportion of patients achieving ETS ≥ 20% or ≥ 30% at week 8, and the impact of ETS and DpR (including by category) on outcome were analysed. Factors associated with ETS and DpR and the optimal ETS/DpR cut-off values for predicting improved overall survival (OS) were assessed.ResultsOverall, 505, 170 and 53 patients had RAS WT mCRC in PRIME, PEAK and PLANET, respectively. Patients receiving panitumumab had higher ETS rates (≥ 30%: PRIME 59% vs. 38%; PEAK 64% vs. 45%) and greater DpR (PRIME: 54% vs. 46%; PEAK: 65% vs. 46%) than those receiving treatment without panitumumab. In multiple regression analyses, panitumumab treatment, liver-only metastases and WT BRAF status were consistently associated with improved ETS and DpR outcomes. Irrespective of treatment, ETS and DpR were associated with improved progression-free survival, overall survival and resection rates; most resections occurred in patients in the two highest DpR categories. In PRIME and PEAK, respectively, the optimal cut-offs for predicting improved OS were 32 and 34% for ETS, and 59 and 70% for DpR.ConclusionsThese exploratory analyses suggest that panitumumab is associated ETS and DpR benefits in patients with RAS WT mCRC and that achieving these endpoints during first-line treatment is linked with favourable outcomes.

Protein biomarkers predictive for response to anti-EGFR treatment in RAS wild-type metastatic colorectal carcinoma

Background:Metastatic colorectal cancer (mCRC) patients with mutant KRAS or NRAS are ineligible for anti-epidermal growth factor receptor (anti-EGFR) therapy, as RAS mutations activate downstream pathways independently of EGFR and induce primary resistance. However, even among RAS wild-type (WT) patients, only a fraction responds to anti-EGFR therapy, suggesting that other mechanisms of resistance exist. We hypothesise that different (epi)genetic alterations can lead to primary anti-EGFR resistance and that the crucial end point is the activation of protein signalling pathways.Methods:We analysed the expression and activation of proteins involved in cell signalling, using reverse phase protein arrays, on a multicentre French cohort of RAS WT mCRC treated with anti-EGFR treatment.Results:We identify activated EGFR and HER3 as protein biomarkers predictive for better overall survival. Active EGFR signalling and downstream PI3K, but not MAPK, pathway activation are associated with response to anti-EGFR treatment. Left-sided mCRC displays active ErbB2/3 and Wnt pathways and a better response to anti-EGFR therapy compared to right-sided mCRC.Conclusions:We identify active EGFR and PI3K signalling as a key factor for response to anti-EGFR treatment in mCRC and highlight the importance of developing these biomarkers in clinical practice for the selection of RAS WT mCRC patients that would benefit from anti-EGFR treatment.

Survival Outcomes in Patients With RAS Wild Type Metastatic Colorectal Cancer Classified According to Köhne Prognostic Category and BRAF Mutation Status

BackgroundKöhne prognostic score is used to classify patients with metastatic colorectal cancer (mCRC) as high, intermediate, or low risk. Using data from 2 phase III trials, we analyzed survival in patients categorized according to Köhne prognostic category and virus-induced rapidly accelerated fibrosarcoma murine sarcoma viral oncogene homolog B (BRAF) mutation. Patients and MethodsPRIME (Panitumumab Randomized Trial In Combination With Chemotherapy for Metastatic Colorectal Cancer to Determine Efficacy) (first-line) and 20050181 (second-line) were studies of chemotherapy with or without panitumumab. Progression-free survival (PFS) and overall survival (OS) were analyzed retrospectively in rat sarcoma viral oncogene homolog (RAS) wild type (WT) and RAS WT+BRAF WT mCRC in each Köhne category, and in BRAF mutant (MT) mCRC. ResultsIn PRIME (n = 495) and 20050181 (n = 420), 53 (11%) and 44 (10%) patients, respectively, had BRAF MT mCRC. Of the RAS WT+BRAF WT/unknown populations, 85/267/90 and 82/211/83 were categorized as high/medium/low risk, respectively. PFS and OS hazard ratios (HRs), adjusted for Köhne group, for patients with RAS WT + BRAF WT/unknown mCRC favored panitumumab with chemotherapy versus chemotherapy alone in both studies. In PRIME, the PFS HR was 0.74 (95% confidence interval [CI], 0.61-0.90) and OS HR was 0.78 (95% CI, 0.64-0.95). In 20050181, PFS and OS HRs were 0.80 (95% CI, 0.65-0.99) and 0.78 (95% CI, 0.62-0.99), respectively. Median PFS and OS were lower in patients with BRAF MT mCRC than in any of the 3 risk categories for patients with RAS WT+BRAF WT/unknown mCRC. ConclusionDuring first- and second-line treatment, Köhne prognostic score allows accurate risk classification in RAS WT mCRC. BRAF MT mCRC should be classified as high risk regardless of other parameters. Panitumumab with chemotherapy might provide survival benefits versus chemotherapy alone in RAS WT and RAS WT+BRAF WT/unknown mCRC, overall and across risk categories.

Eph A2 expression is a predictive biomarker of poorer activity and efficacy of FOLFIRI + cetuximab in RAS WT metastatic colorectal cancer (mCRC) patients (pts) in the CAPRI GOIM trial

Background: Eph A2 promotes tumor growth, invasiveness and angiogenesis in mCRC. Targeting Eph A2 could overcome resistance to anti-epidermal growth factor receptor (EGFR) treatment in colon cancer preclinical models. Methods: Formalin-fixed paraffin-embedded tumor specimens from 82 RAS wild type (WT) mCRC pts treated with cetuximab + FOLFIRI as first line therapy in the CAPRI GOIM trial were assessed for Eph A2 expression by immunohistochemistry. Eph A2 levels were evaluated developing an HSCORE [1 × (% cells 1+) + 2 × (% cells 2+) + 3 × (% cells 3+)] (range: 0-300). A cut off was set by ROC analysis to define high (>50) and low (≤50) Eph A2 levels. Results: Eph A2 expression was found in 55/82 (67%) cases. According to HSCORE Eph A2 levels were low in 54 (66%) and high in 28 (34%) samples. Eph A2 expression resulted in mostly complete membranous staining. Tumor stroma was positive in 15/82 (18%) cases. In most of these cases an intense immune infiltrate was observed. Non-tumor adjacent normal mucosa was assessable in 34/82 samples. Eph A2 was expressed in 16/34 (47%), more frequently in dysplastic epithelial areas. A significant correlation between Eph A2 expression in tumor and stroma was found (p < 0.0001). Eph A2 was more frequently expressed in less differentiated tumors (p = 0.02), as well as in left-sided tumors compared to right-sided tumors [17/28 (61%), 11/28 (39%), respectively p = 0.04]. Eph A2 expression was associated with higher rate of disease progression (PD) 8/28 (29%) vs 5/54 (9%) (p = 0.02), and with worse median PFS [8.6 m (CI95% 6.4-10.8) vs 12.3 m (CI95% 10.4-14.2) p = 0.030], both in left and right-sided tumours. Moreover, median OS was 28.4 m (CI95% 13.1-43.7) vs 39.8 m (CI95% 30.2-49.4), although this result did not reach statistical significance (p = 0.23). Conclusion: Eph A2 levels were significantly associated with a worse PFS and an increase in PD in RAS WT mCRC pts treated with cetuximab + FOLFIRI as first line therapy in the CAPRI GOIM trial in both right and left-sided tumors. A similar trend was observed for OS. Eph A2 might represent an additional predictive biomarker of lack of efficacy in RAS WT mCRC pts treated with FOLFIRI + cetuximab.

583P - Impact of tumor location on the efficacy of first-line anti-EGFR monoclonal antibody plus chemotherapy in patients (pts) with metastatic colorectal cancer (mCRC): Retrospective analyses of the randomized MACRO-2 and PLANET trials from TTD Group

Background: mCRC is a group of heterogeneous diseases rather than a homogeneous one, resulting in clinical and molecular characteristics between right- and left-sided tumors driving to different prognosis. Methods: Pts with KRAS Wild-Type (WT) mCRC treated in 1st-line with EGFR monoclonal antibody inhibitors (EGFRI) plus either FOLFOX or FOLFIRI from two randomized phase II trials (MACRO-2/PLANET) were included in the analysis. Pts were classified according to their primary tumor location as right-sided or left-sided. The main objective was to analyze the effect of primary tumor location on objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). Differential responses in RAS WT pts according to tumor location were also evaluated. Results: Pts with KRAS WT left-sided primary tumors (N = 209) versus right-sided primary tumors (N = 52) were analyzed. RAS was retrospectively determined in 69% of pts. Both KRAS and RAS WT left-sided had significantly superior ORR, median PFS and median OS compared with right-sided (Table).Table583PKRAS WTRAS WTRight-sided (N = 52)Left-sided (N = 209)Right-sided (N = 33)Left-sided (N = 148)ORR (confirmed)Rate, %25.046.933.352.7OR (95% CI)0.38 (0.19 – 0.75)0.45 (0.20 – 0.99)P-value0.0040.044PFSMedian, m (95% CI)7.209.866.5410.09(4.21 – 11.14)(9.13 – 11.73)(3.91 – 12.58)(9.43 – 12.06)HR (95% CI)0.64 (0.44 – 0.92)0.63 (0.40 – 0.99)P-value0.0160.044OSMedian, m (95% CI)13.5727.7313.5732.79(8.44 – 26.02)(24.97 – 36.17)(8.41 – 34.23)(26.45 – 39.85)HR (95% CI)0.47 (0.33 – 0.67)0.44 (0.28 – 0.68)P-value<0.00010.0002CI: confidence intervals; HR: hazard ratio; m: months; OR: odds ratio; ORR: objective response rate; OS: overall survival; PFS: progression-free survival WT: wild-type. Open table in a new tab CI: confidence intervals; HR: hazard ratio; m: months; OR: odds ratio; ORR: objective response rate; OS: overall survival; PFS: progression-free survival WT: wild-type. Conclusions: Pts with Left-sided primary tumors KRAS or RAS WT mCRC treated with first-line EGFRI plus chemotherapy have significantly improved efficacy outcomes as compared with pts with right-sided primary tumors KRAS or RAS WT mCRC Clinical trial identification: MACRO-2 trial: NCT01161316, PLANET trial: NCT00885885 Legal entity responsible for the study: Spanish Cooperative Group for the Treatment of Digestive Tumors (TTD) Funding: Amgen SA (PLANET), Merck. S. L. (MACRO-2) Disclosure: C. Guillen-Ponce: Consultant or advisory role, travel and accommodation: Roche Pharma, Merck Serono. E. Diaz Rubio: Consultant or advisory role, research funding: Bayer, Amgen and Merck. E. Aranda Aguilar: Advisory role: Amgen, Bayer, Celgene, Merck, Roche, Sanofi. All other authors have declared no conflicts of interest.

Clinical Features and Outcomes of Patients with Colorectal Cancers Harboring NRAS Mutations.

Purpose:NRAS mutations are now routinely included in RAS testing prior to EGFR inhibitor therapy for metastatic colorectal cancer (mCRC). The clinical implications of NRAS mutation beyond lack of response to anti-EGFR therapy, however, are not known. We undertook this study to determine the clinical features and treatment outcomes of patients with NRAS-mutant mCRC.Experimental Design: We reviewed clinical characteristics, concurrent mutations, and outcomes for all mCRC cases with NRAS mutations undergoing standard genotyping at our institution from 2008 to 2015. Comparison groups consisted of RAS wild-type and KRAS-mutant mCRC consecutive cases genotyped from 2008 to 2012.Results: Three percent (87/2764) of mCRC patients had NRAS-mutant tumors (45% exon 2 and 55% exon 3), including three cases with concurrent NRAS and KRAS mutations. Left-sided primary site and African American self-reported race were associated with NRAS mutation (P < 0.01). Resection rate at 12 months was lower for NRAS-mutant mCRC than for RAS wild-type or KRAS-mutant mCRC. Median survival from time of first known metastasis was 33 months for NRAS-mutant, 47 months for KRAS-mutant, and 78 months for RAS wild-type cases (P < 0.001). Multivariate analysis assigned an HR for overall survival of 2.0 for NRAS mutation and 1.5 for KRAS mutation (P < 0.01).Conclusions:NRAS defines a molecular subset with distinct clinical characteristics from KRAS-mutant and wild-type mCRC. NRAS mutations are enriched in left-sided primary tumors and among African Americans. Mutations in NRAS are associated with poor survival and worse outcomes than either KRAS-mutant or wild-type mCRC. Clin Cancer Res; 23(16); 4753-60. ©2017 AACR.

Anti-EGFR monoclonal antibody panitumumab for the treatment of patients with metastatic colorectal cancer: an overview of current practice and future perspectives

ABSTRACTIntroduction: Targeted agents alone or in combination with chemotherapy are current standard of treatment for metastatic colorectal cancer (mCRC). Panitumumab is a fully human monoclonal antibody which inhibits the epidermal growth factor receptor (EGFR). It is currently approved in combination with chemotherapy in first- and second-line and as a monotherapy in chemorefractory patients. RAS gene mutations confer resistance to anti-EGFR agents; thus, panitumumab is restricted to the treatment of RAS wild-type (WT) tumors.Areas covered: This review explores the available data on panitumumab and presents new perspectives on predictive markers of anti-EGFR efficacy including primary tumor sidedness and BRAF mutations. Other details covered include panitumumab’s mechanism of action, pharmacokinetics, pharmacodynamics and safety aspects of the therapy as well as mechanisms of secondary resistance and future prospects of treatment in different settings.Expert opinion: Panitumumab has significantly added to the treatment armamentarium for RAS WT mCRC. The effort spent in identifying predictive biomarkers of panitumumab efficacy has been of pivotal importance to development of the molecular selection of patients with mCRC. Primary and secondary resistance, however, still represent important issues. Novel strategies to overcome those issues are currently underway with promising results which highlight the potential use of panitumumab in combination with other targeted agents in the future.