Irinotecan-refractory Metastatic Colorectal Cancer Research Articles

Randomised phase II study of panitumumab plus irinotecan versus cetuximab plus irinotecan in patients with KRAS wild-type metastatic colorectal cancer refractory to fluoropyrimidine, irinotecan and oxaliplatin (WJOG 6510G)

BackgroundCetuximab has been shown to be clinically active when given in combination with irinotecan in patients with irinotecan-refractory metastatic colorectal cancer (mCRC). However, it has remained unclear whether panitumumab is effective when combined with irinotecan. We compared efficacies of both regimens in this randomised phase II study. Patients and methodsPatients with wild-type KRAS exon 2 mCRC previously treated with fluorouracil-, oxaliplatin- and irinotecan-based chemotherapies were randomised (1:1) to either panitumumab plus irinotecan (panitumumab arm) or cetuximab plus irinotecan (cetuximab arm). The primary end-point was progression-free survival (PFS). The planned sample size was 120, expecting a hazard ratio (HR) of 1.0 with non-inferiority margin of 1.3 (one-sided alpha error 0.2 and power 0.7). Major secondary end-points were overall survival (OS), response rate and safety. ResultsFrom December 2011 to September 2014, 121 patients were enrolled, and 61 and 59 patients were randomised to the panitumumab and cetuximab arms, respectively (1 patient excluded). Most patients (97%) had received prior chemotherapies containing bevacizumab. The median PFS was 5.42 months in the panitumumab arm and 4.27 months in the cetuximab arm (HR = 0.64, 95% confidence interval [CI] = 0.44–0.94, P < 0.001 for non-inferiority, P = 0.058 for superiority), and median OS was 14.85 and 11.53 months (HR = 0.66, 95% CI = 0.44–1.00, P = 0.050 for superiority), respectively. The incidence of grade 3 or 4 hypomagnesaemia was higher in the panitumumab arm than that in the cetuximab arm (17% vs. 7%). ConclusionPanitumumab may be non-inferior to cetuximab in combination with irinotecan in survival of patients with irinotecan-refractory mCRC.

Irinotecan, cetuximab, and bevacizumab (CBI) versus irinotecan, cetuximab, and placebo (CI) in irinotecan-refractory metastatic colorectal cancer (mCRC): Results from an ACCRU network randomized phase II trial.

102 Background: Combination irinotecan and cetuximab is approved for irinotecan-refractory mCRC; it is unknown if the addition of bevacizumab would improve outcomes. We studied the efficacy and safety of CBI compared with CI in patients (pts) with RAS wildtype, irinotecan-refractory mCRC. Methods: In this multicenter, randomized, double-blind, placebo-controlled phase II trial, pts with RAS wildtype mCRC and no prior anti-epidermal growth factor receptor therapy who failed at least 1 irinotecan-based chemotherapy regimen and received bevacizumab in at least 1 prior line of therapy were randomized 1:1 to irinotecan 180 mg/m2 (or previously tolerated dose), cetuximab 500 mg/m2, and bevacizumab 5 mg/kg vs CI every 2 wks until disease progression, intolerable toxicity, or withdrawal of consent. The primary endpoint was progression free survival (PFS). Multivariable Cox proportional hazard models stratified by number of prior lines of therapy and bevacizumab receipt in immediate prior line were performed. Secondary endpoints included overall survival (OS), objective response rate (ORR), and adverse events (AEs). The study was closed early in January 2018 for reasons related to accrual and funding after enrollment of 36 out of a planned 60 pts. Results: Between July 2015 and December 2017, 36 pts were randomized (19 to CBI, 17 to CI). 34 pts (94%) were treated with 2 or more prior chemotherapy regimens. Baseline characteristics were similar between arms. Median PFS was 9.7 vs 5.5 mo for CBI and CI arms, respectively (log-rank P =0.76; multivariable HR = 0.64; 95% CI, 0.25-1.66). Median OS was 19.7 vs 10.2 mo for CBI and CI (log-rank P= 0.04; multivariable HR = 0.41; 95% CI, 0.15-1.09). ORR was 37% for CBI vs 12% for CI ( P =0.13). Grade 3 or higher AEs occurred in 47% of pts receiving CBI vs 35% for CI ( P =0.46). Conclusions: In this prematurely discontinued trial, there were non-significant increases in PFS and ORR and a statistically significant 9.5 mo increase in median OS in favor of CBI compared to CI. Further investigation of CBI for treatment of irinotecan-refractory mCRC is warranted. Clinical trial information: NCT02292758.

A phase 2 study of panitumumab with irinotecan as salvage therapy in chemorefractory KRAS exon 2 wild-type metastatic colorectal cancer patients

BackgroundTargeted agents are standard treatment for RAS wild-type metastatic colorectal cancer in the first- and second-line settings. This phase 2 study determined the benefit of targeting the epidermal growth factor receptor (EGFR) with panitumumab plus irinotecan in irinotecan-refractory patients.MethodsKRAS exon-2 wild-type patients failing prior irinotecan received panitumumab (6 mg/kg) and irinotecan (180 mg/m²) every 2 weeks. The primary endpoint was the overall response rate (ORR). Secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS). KRAS exon-2 status was evaluated centrally, along with NRAS, BRAF mutations, epiregulin, amphiregulin, PTEN and EGFR copy number status, and correlated with efficacy.ResultsSixty-one patients were treated. Among the 46 wild-type RAS patients, the ORR was 15.2% (seven partial responses), with median PFS of 3.8 months (95% CI 2.7–4.3) and median OS of 12.5 months (95% CI 6.7–15.9). Wild-type BRAF patients showed a 13.0% response rate. No significant correlations between response and baseline biomarker expression were identified. Common grade 3–4 adverse events were diarrhoea and rash (18.0% each), hypomagnesaemia and asthenia (8.2% each).ConclusionsThe addition of panitumumab to irinotecan as salvage therapy is feasible but has limited activity in irinotecan-refractory metastatic colorectal cancer. No biomarkers predictive of response were identified.

EGFR Gene Amplification and KRAS Mutation Predict Response to Combination Targeted Therapy in Metastatic Colorectal Cancer.

Genetic variability in KRAS and EGFR predicts response to cetuximab in irinotecan refractory colorectal cancer. Whether these markers or others remain predictive in combination biologic therapies including bevacizumab is unknown. We identified predictive biomarkers from patients with irinotecan refractory metastatic colorectal cancer treated with cetuximab plus bevacizumab. Patients who received cetuximab plus bevacizumab for irinotecan refractory colorectal cancer in either of two Phase II trials conducted were identified. Tumor tissue was available for 33 patients. Genomic DNA was extracted and used for mutational analysis of KRAS, BRAF, and p53 genes. Fluorescence in situ hybridization was performed to assess EGFR copy number. The status of single genes and various combinations were tested for association with response. Seven of 33 patients responded to treatment. KRAS mutations were found in 14/33 cases, and 0 responded to treatment (p=0.01). EGFR gene amplification was seen in 3/33 of tumors and in every case was associated with response to treatment (p<0.001). TP53 and BRAF mutations were found in 18/33 and 0/33 tumors, respectively, and there were no associations with response to either gene. EGFR gene amplification and KRAS mutations are predictive markers for patients receiving combination biologic therapy of cetuximab plus bevacizumab for metastatic colorectal cancer. One marker or the other is present in the tumor of half of all patients allowing treatment response to be predicted with a high degree of certainty. The role for molecular markers in combination biologic therapy seems promising.

Abstract CT119: Early results from a phase II study of RRx-001, a novel, triple epigenetic inhibitor, showing resensitization to irinotecan in colorectal cancer

Abstract Background: Resistance acquisition to standard therapy in advanced colon cancer leads to poor patient survival. Epigenetic therapies can potentially reverse the chemoresistant phenotype. RRx-001, a novel ROS-mediated epigenetic modifier may resensitize to irinotecan-based therapies and increase overall survival compared to standard third-line regorafenib. Methods: The phase II ROCKET study evaluates a sequential rechallenge to irinotecan-based therapies after RRx-001 or regorafenib. Patients with an ECOG PS 0-1 with irinotecan-refractory metastatic colorectal cancer who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5 mg/m2 IV 1x/week or regorafenib 160 mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies. The primary end point is overall survival with secondary endpoints to investigate resensitization. The study is planned to accrue approx. 190 patients and recruitment is ongoing. Study Status and Results: To date, 23 patients have been randomized with 10 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in all 6 patients as compared to 4 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Conclusions: Early results in this study suggest that resensitization to irinotecan-based therapies mediated by RRx-001, a systemically non-toxic novel epigenetic inhibitor, may be a general effect. These early results are intriguing and may predict for increased overall survival, adding an additional regimen after disease progression. The trial is continuing. Citation Format: Tony Reid, George Fisher, Corey Carter, Cheryl Cho-Phan, Pamela Kunz, Bryan Oronsky, Gary R. Fanger, Scott Caroen, Christopher Parker, Jan Scicinski. Early results from a phase II study of RRx-001, a novel, triple epigenetic inhibitor, showing resensitization to irinotecan in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT119. doi:10.1158/1538-7445.AM2015-CT119

The Development Of RRx-001, A Novel Nitric-Oxide-Mediated Epigenetically Active Anticancer Agent

RRx-001 is a novel NO and hypoxia mediated anticancer agent with epigenetic activity. In the first-in-human, Phase I trial, 5/5 patients who progressed on RRx-001 treatment were resensitized to previously refractory therapy, hinting at a generalized resensitization effect. A randomized open-label multi-part, multi-center phase II trial of RRx-001 versus regorafenib (ROCKET) has commenced to explore the resensitization and/or 'episensitization' potential in irinotecan refractory tumors and its impact on overall survival. Patients with irinotecan-refractory metastatic colorectal cancer with an ECOG PS 0-1 who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5mg/m2 IV 1x/week or regorafenib 160mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies. To date, 26 patients have been randomized with 18 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in 12/13 patients as compared to 5 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Progression free survival (ongoing) for RRx-001+irinotecan is 4.9 months compared 1.8 months on Regorafenib+irinotecan. Early results in the ROCKET study suggest that RRx-001-mediated resensitization to previously refractory therapies may have a generalized effect, independent of KRAS or p53 status. These early results are intriguing, suggesting improved QOL and overall survival over currently approved therapy in the chemotherapy refractory colorectal cancer.

O3.8 - Early Results: “ROCKET” a phase II Study of RRx-001, a novel triple epigenetic inhibitor, Resensitization to Irinotecan in Colorectal Cancer

ABSTRACT Background: RRx-001 is a novel broad-spectrum anticancer agent that triply inhibits DNA methyltransferases (DNA MTases), Histone Deacetylases (HDAC), and Lysine Demethylases. In the first-in-human, Phase I trial, 5/5 patients who progressed on RRx-001 treatment were resensitized to previously refractory irinotecan therapy, hinting at a generalized resensitization effect. A randomized open-label multi-part, multi-center phase II trial of RRx-001 versus regorafenib (ROCKET) is underway to explore the resensitization and/or ‘episensitization’ potential in irinotecan refractory tumors and its impact on overall survival. Methods: Patients with irinotecan-refractory metastatic colorectal cancer with an ECOG PS 0–1 who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5 mg/m2 IV 1x/week or regorafenib 160 mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies. Results: To date, 23 patients have been randomized with 10 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in all 6 patients as compared to 4 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Progression free survival (ongoing) for RRx-001 + irinotecan is 5.9 months compared 0.92 months on Regorafenib + irinotecan. Combined Disease Control Rate (SD + PR) for the combination of RRx-001 and reintroduction of Irinotecan based therapy is currently 100%, whereas no patients to date randomized to the regorafenib arm have been able to start irinotecan based therapy secondary to decreasing performance status. Conclusions: Early results in the ROCKET study suggest that RRx-001-mediated resensitization to previously refractory therapies may have a generalized effect, independent of KRAS or p53 status. These early results are intriguing and may be a major advancement in epigenetic therapy. RRx-001 is a novel pan-epigenetic inhibitor that may potentially offer improved QOL and overall survival over currently approved therapy in the chemotherapy refractory colorectal cancer.

Prospective analysis of the early modulation of plasma amphiregulin (AR) during treatment with cetuximab and irinotecan in irinotecan-refractory metastatic colorectal cancer (mCRC) patients (pts).

3602 Background: The potential role of AR tissue levels in the prediction of benefit from anti-EGFRs in mCRC pts was suggested by retrospective series. Preclinical and preliminary clinical experiences showed a modulation of plasma EGFR ligands during the treatment with cetuximab. Previous data by our group evidenced that a significant increase of plasma AR occurred one hour after the administration of cetuximab and higher increases were associated with worse clinical outcome in KRAS and BRAFwt irinotecan-refractory mCRC pts receiving cetuximab and irinotecan. Methods: We designed a prospective confirmatory study in the same setting of mCRC pts. To detect a HR for PFS of 2.3 for pts with high AR levels one hour after the administration of cetuximab (1hr-AR) compared to those with low levels, with two-sided a=0.05 and b=0.2, 45 events were required. The median value was adopted as cut-off. Plasma AR levels were assessed by means of validated ELISA kits. Results: Forty-nine KRAS and BRAFwt pts were included. A significant early increase of AR levels was observed (median increase +24.7%; median levels of baseline AR and 1hr-AR: 18.06 and 24.06 pg/mL, respectively; Wilcoxon signed rank test, p&lt;0.0001). At a median follow-up of 20.4 mos, median PFS and OS were 4.6 and 12.1 mos, respectively. No differences in PFS or OS were observed according to 1hr-AR levels (median PFS 5.5 vs 4.6 mos, HR: 0.76 [95%CI:0.40-1.32], p=0.322; median OS: 15.6 vs 13.4 mos, HR:0.77 [95%CI:0.36-1.62], p=0.485). Conclusions: This prospective experience confirms that AR early increases one hour after the administration of cetuximab. Underlying biological mechanisms should be investigated. Nevertheless, this modulation of AR does not predict clinical outcome. Our work underlines the need to prospectively validate retrospective findings in independent series, to assess their reliability. Clinical trial information: 2008-003160-19.

Intrapatient Cetuximab Dose Escalation in Metastatic Colorectal Cancer According to the Grade of Early Skin Reactions: The Randomized EVEREST Study

Skin toxicity in patients receiving cetuximab has been associated positively with clinical outcome in several tumor types. This study investigated the effect of cetuximab dose escalation in patients with irinotecan-refractory metastatic colorectal cancer who had developed no or mild skin reactions after 21 days of treatment at the standard dose. This article reports clinical and pharmacokinetic (PK) data. After 21 days of standard-dose cetuximab (400 mg/m(2) initial dose, then 250 mg/m(2) per week) plus irinotecan, patients with ≤ grade 1 skin reactions were randomly assigned to standard-dose (group A) or dose-escalated (to 500 mg/m(2) per week; group B) cetuximab. Patients with ≥ grade 2 skin reactions continued on standard-dose cetuximab plus irinotecan (group C). The intent-to-treat population comprised 157 patients. PK profiles reflected the dose increase and were predictable across the dose range investigated. Weekly cetuximab doses of up to 500 mg/m(2) were well tolerated, and grade 3 and 4 adverse events were generally comparable between treatment groups. Dose escalation (n = 44) was associated with an increase in skin reactions ≥ grade 2 compared with standard (n = 45) dosing (59% v 38%, respectively). Dose escalation, compared with standard dosing, showed some evidence for improved response rate (30% v 16%, respectively) and disease control rate (70% v 58%, respectively) but no indication of benefit in relation to overall survival. In an exploratory analysis, dose escalation seemed to increase response rate compared with standard dosing in patients with KRAS wild-type but not KRAS mutant tumors. Cetuximab serum concentrations increased predictably with dose. Higher dose levels were well tolerated. The possible indication for improved efficacy in the dose-escalation group warrants further investigation.

Cetuximab in the treatment of patients with colorectal cancer

Introduction: Cetuximab is a chimeric mAb with avidity for the EGFR higher than that of the natural ligands of the receptor. Preclinical studies showed that cetuximab demonstrated synergy with topoisomerase I inhibitors in the treatment of human colorectal cancer (CRC) cell lines in vivo. Subsequent clinical trials have shown that cetuximab can reverse resistance to topoisomerase I inhibitors in addition to having modest monotherapy activity. These studies led to accelerated provisional FDA approval of the drug for the treatment of patients with irinotecan-refractory metastatic CRC. Its clinical utility has been improved with the discovery of negative predictive biomarkers; these have shown that there is a lack of cetuximab benefit for patients whose tumors generally harbor a KRAS mutation, thus sparing these patients the toxicity of the agent which would not be of treatment benefit.Areas covered: This review covers the last decade of clinical trials that have determined the toxicity and efficacy of cetuximab when given to patients with CRC, as well as some of the molecular subgroups tumors from patients with CRC who appear to not derive benefit from this mAb.Expert opinion: Cetuximab has modest single-agent efficacy in the treatment of patients with metastatic CRC whose tumors do not harbor a KRAS mutation. In combination with irinotecan, it is associated with an overall survival (OS) and progression-free survival (PFS) advantage in first-line therapy in patients with KRAS non mutant metastatic CRC; it can be combined with irinotecan to overcome resistance in patients with KRAS non mutant CRC who have previously progressed on prior irinotecan chemotherapy. Future studies of putative biomarkers are likely to give additional information to clearly define which patients with metastatic CRC receive therapeutic benefit from cetuximab and other monoclonal anti-EGFR therapies.

Cetuximab plus irinotecan in pretreated metastatic colorectal cancer patients: The ELSIE study

To evaluate the efficacy and safety of cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer (mCRC) patients from South-East Asia and Australia. In this open-label, phase II study, the main eligibility criteria were epidermal growth factor receptor-positive mCRC with progressive disease within 3 mo of an irinotecan-based regimen as the most recent chemotherapy. Patients received cetuximab 400 mg/m2 initially, then 250 mg/m2 every week, with the same regimen of irinotecan on which the patients had progressed (4 pre-defined regimens allowed). The primary objective was evaluation of progression-free survival (PFS) at 12 wk. Secondary objectives included a further investigation of PFS, and an assessment of the overall response rate (ORR), duration of response, time to treatment failure (TTF), overall survival and the safety profile. One hundred and twenty nine patients were enrolled from 25 centers in the Asia-Pacific region and of these 123 received cetuximab plus irinotecan. The most common recent irinotecan regimen used was 180 mg/m2 every 2 wk which had been used in 93 patients (75.6%). The PFS rate at 12 wk was 50% (95% confidence interval (CI, 41-59) and median PFS time was 12.1 wk (95% CI: 9.7-17.7). The ORR was 13.8% (95% CI: 8.3-21.2) and disease control rate was 49.6% (95% CI: 40.5-58.8). Median duration of response was 31.1 wk (95% CI: 18.0-42.6) and median overall survival was 9.5 mo (95% CI, 7.5-11.7). The median TTF was 11.7 wk (95% CI: 9.1-17.4). Treatment was generally well tolerated. The most common grade 3/4 adverse events were diarrhea (13.8%), neutropenia (8.9%), rash (5.7%) and vomiting (5.7%). In patients from Asia and Australia, this study confirms the activity and safety of cetuximab plus irinotecan observed in previous studies in Europe and South America.

A phase II trial of cetuximab/irinotecan every 2 weeks in patients with metastatic colorectal cancer (CRC) that expresses wild-type KRAS after failure to first-line therapy with an irinotecan-containing regimen with or without detectable epidermal growth factor receptor (EGFR) expression.

e14112 Background: Cetuximab plus irinotecan has been proven to be effective in patients (pts) with irinotecan-refractory metastatic colorectal cancer (mCRC) which express wild-type (WT) KRAS and EGFR(+). Retrospective analysis revealed that mCRC with undetectable EGFR (EGFR−) by immunohistochemistry (IHC) also showed similar efficacy to cetuximab. There has not been a prospective study to investigate the efficacy of cetuximab for mCRC pts with EGFR−. Methods: This is a prospective, nonrandomized multicenter phase II study. Between Mar. 2008 and Oct. 2009, 40 pts (20 EGFR+ and 20 EGFR− in each study arm, respectively) were enrolled. Main eligibility criteria were histologically proven adenocarcinoma expressing WT-KRAS, failed to first-line irinotecan-containing chemotherapy. EGFR expression was determined by IHC (PharmDx; Dako Corporation, Carpentino, CA, USA). Pts were treated with biweekly cetuximab (500 mg/m2) and irinotecan (150-180 mg/m2) as second-line chemotherapy. Primary endpoint was to investigate response rate (RR), and secondary endpoints were to evaluate toxicity, progression-free survival (PFS) and overall survival (OS). Results: Baseline characteristics were balanced between both arms. The overall RR was 45% (18/40, 95% CI 29.6-60.4), 55% (11/20) in EGFR+ and 35% (7/20) in EGFR− arm. Overall median PFS was 7.1 months (mo) (95% CI 5.2-9.1); 8.3 mo in EGFR+ and 5.8 mo in EGFR− arm. Median OS was not reached yet; 1-year survival rate was 81.1%, 86.6% in EGFR+ and 78.7% in EGFR− arm. Grade 3 or 4 toxicities included neutropenia in 5 pts (12.5%), and febrile neutropenia/asthenia in 2 pts (5%), respectively. Grade 2 or 3 skin rash were observed in 70% of pts (14/20) in EGFR+ and 55% (11/20) in EGFR− arm. Conclusions: Biweekly cetuximab plus irinotecan was feasible and well tolerated as a second-line treatment in mCRC. This combination showed significant anti-tumor activity in irinotecan-refractory mCRC pts with WT-KRAS regardless of EGFR expression of the tumor. No significant financial relationships to disclose.

Cetuximab Given Every 2 Weeks plus Irinotecan Is an Active and Safe Option for Previously Treated Patients with Metastatic Colorectal Cancer

Background: We gathered data from multiple institutions on the cetuximab regimen of patients with metastatic colorectal cancer. Methods: 126 patients from 19 centers were included from July 2006 to July 2007 in this prospective non-controlled study. Irinotecan-refractory metastatic colorectal cancer patients with Karnofsky ≧70 received cetuximab 500 mg/m² every 2 weeks (q2w) in combination with irinotecan 180 mg/m² q2w until disease progression or unacceptable toxicity. The primary endpoint was the progression-free rate at 12 weeks. Results: Median age was 65 years; 65.9% male; colon/rectum 64.3/34.1%; Karnofsky status ≤80/≧90% in 45.3/54.7% of the patients. The progression-free rate was 42.7 (95% CI 32.8–52.6) and 22.4% (95% CI 14.2–30.7) at 12 and 24 weeks, respectively. The main grade 3 or 4 toxicities were: diarrhea 13.5% and acne-like rash 10.3%. No grade 3 or 4 infusional or allergic reactions were reported. Conclusions: The progression-free rates confirm that cetuximab q2w in combination with irinotecan is an option, and is as active and safe as the standard weekly regimen.

Personalized cancer therapy coming of age: clinical highlights in 2009 and future directions.

Brigette BY Ma Author for correspondence: LKS Specialist Clinic, Department of Clinical Oncology, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China Tel.: +852 2632 2118 Fax: +852 2648 7097 brigette@clo.cuhk.edu.hk and State Key Laboratory in Oncology in South China, Hong Kong SAR, China and Sir YK Pao Centre for Cancer, Hong Kong SAR, China and Hong Kong Cancer Institute, Hong Kong SAR, China and Chinese University of Hong Kong, Hong Kong SAR, China

MDR1 polymorphism role in patients treated with cetuximab and irinotecan in irinotecan refractory colorectal cancer

The aim of the study was to evaluate the influence of the MDR1 C3435T polymorphism on the therapeutic response in 23 patients treated with cetuximab plus irinotecan for irinotecan refractory liver metastatic colorectal cancer considering their KRAS status. Indeed, irinotecan and its active metabolite (SN-38) are both substrates of P-glycoprotein (P-gp) encoded by MDR1. Patients received cetuximab and irinotecan up to progression. The overall survival was 55% at 10months. Overall, four patients had an undetermined KRAS status and two patients with mutated KRAS were in progression disease. The response to treatment was observed after 3months among the 17 wild-type KRAS patients. Two patients presented a progressive disease (1 TT and 1 CT), eight patients had a stable disease (5 CC and 3CT) and five patients had a partial response (3 CC and 2 CT). Importantly, 2 patients (2 TT) were in complete response and still alive 5years after starting the treatment, which suggests that the combination of wild-type KRAS and MDR1 3435 TT may be a factor of good prognosis. These results suggest that EGFR inhibition by cetuximab may overcome this irinotecan resistance by abrogating drug efflux depending on MDR1 3435 polymorphism. Among patients resistant to irinotecan, it is still possible to use the association of cetuximab plus irinotecan to obtain a complete resection of hepatic metastases that is necessary to improve their survival.

Cancer drugs in the real world

Cancer drugs in the real world

Impact of FcγRIIa-FcγRIIIa Polymorphisms and KRAS Mutations on the Clinical Outcome of Patients With Metastatic Colorectal Cancer Treated With Cetuximab Plus Irinotecan

The antiepidermal growth factor receptor antibody cetuximab shows activity in irinotecan-refractory metastatic colorectal cancer (mCRC), mainly in wild-type KRAS tumors. Cetuximab may also exert antitumor effects through antibody-dependent cell-mediated cytotoxicity (ADCC) in which antibody Fc portion interacts with Fc receptors (FcgammaRs) expressed by immune cells. ADCC is influenced by FcgammaRIIa-H131R and FcgammaRIIIa-V158F polymorphisms that are clinically relevant in follicular lymphoma and metastatic breast cancer treated with rituximab and trastuzumab, respectively. We investigated the association of FcgammaR polymorphisms and KRAS mutation with the outcome of irinotecan-refractory mCRC patients treated with cetuximab plus irinotecan. Tumor and normal tissues from 69 patients were screened for KRAS mutations using a sensitive multiplex assay and genotyped for FcgammaRIIa and FcgammaRIIIa polymorphisms by direct sequencing and multiplex allele-specific polymerase chain reaction, respectively. The results were correlated with response and progression-free survival (PFS). KRAS mutations were associated with lower response rate (4% v 27% in nonmutated patients; P = .021) and shorter PFS (3.0 v 5.3 months; P = .021). Patients with FcgammaRIIa-131H/H and/or FcgammaIIIa-158V/V genotypes had longer PFS than 131R and 158F carriers (5.5 v 3.0 months; P = .005). The difference remained significant for mutated-KRAS patients. By multivariate analysis, KRAS mutation and FcgammaR combined status were independent risk factors for PFS. Combined FcgammaRIIa/FcgammaRIIIa polymorphisms are prognostic factors for disease progression in mCRC patients treated with cetuximab plus irinotecan. As these polymorphisms are also clinically relevant in mutated-KRAS mCRC, an important role of ADCC in cetuximab efficacy is presumed.

Relationship of efficacy with KRAS status (wild type versus mutant) in patients with irinotecan-refractory metastatic colorectal cancer (mCRC), treated with irinotecan (q2w) and escalating doses of cetuximab (q1w): The EVEREST experience (preliminary data)

4001 Background: We previously demonstrated in the EVEREST trial that, in pts with mCRC after failure of irinotecan-based therapy, the efficacy could be improved by escalating the dose of cetuximab in combination with standard-regimen irinotecan (180 mg/m2 q2w) compared with standard-dose cetuximab for pts with grade 0/1 skin reactions. It has been suggested that KRAS mutation status may be a predictor for tumor response to anti-EGFR treatment. The question remains of whether dose escalation is also able to induce response in pts with mutated KRAS. Methods: Pts with grade 0/1 skin reactions after 22 days of treatment with irinotecan and standard-dose cetuximab were randomized to receive standard dose (250 mg/m2) (Arm A) or escalated (up to 500 mg/m2) (Arm B) doses of cetuximab. Archived tissue from 77 of 89 randomized pts was analyzed for KRAS mutation status. Efficacy parameters were determined and compared with the outcome of KRAS mutation analysis. Results: In Arm A, 45 pts were randomized: 19 pts (42%) were KRAS wt, 19 pts (42%) were KRAS mt, and 7 pts (16%) were non-evaluable for the preliminary analysis. In Arm B, 44 pts were randomized and the figures were 28 (64%), 11 (25%), and 5 (11%), respectively. Updated data including PFS and additional correlations of KRAS status with ligands and mRNA predictive signatures will be presented. Conclusions: These data suggest that patients with KRAS wt achieve considerable benefit from irinotecan plus cetuximab treatment. Patients with KRAS mt did not profit from irinotecan plus cetuximab treatment and cetuximab dose escalation did not increase responses in these patients. Response rate Arm A Arm B KRAS wt 4/19 (21.1%) 13/28 (46.4%) KRAS mt 0/19 0/11 Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Merck, Merck Serono Merck Merck Merck, Merck Serono

Assessment of Baseline Clinical Predictive Factors of Response to Cetuximab-Irinotecan in Patients with Irinotecan-Refractory Metastatic Colorectal Cancer

Objective: To identify easily available predictive factors of response to cetuximab-irinotecan in patients with irinotecan-refractory metastatic colorectal cancer. Methods: Retrospective analysis of patients treated with cetuximab (400 mg/m² in week 1, 250 mg/m² in subsequent weeks) plus irinotecan (180 mg/m² every 2 weeks). We assessed demographic data, prior response to chemotherapy, number of metastatic sites, disease and metastatic disease durations, irinotecan-free interval and tumoral immunohistochemical epidermal growth factor receptor status. Results: We analyzed 311 patients. Objective response rate under cetuximab-irinotecan was 26%. In univariate analysis, prior response to irinotecan, presence of only 1 metastatic site, disease duration, metastatic disease duration and irinotecan-free interval equal or above median (24, 18 and 1.8 months, respectively) were predictive of response to cetuximab-irinotecan. Multivariate analysis confirmed independent predictive value of prior response to irinotecan, number of metastatic sites and disease duration. Conclusion: Prior response to irinotecan, number of metastatic sites and disease duration may contribute to better select patients suitable for cetuximab-irinotecan therapy.

Retrospective Analysis of Patients Treated with Cetuximab plus FOLFIRI for Previous Irinotecan-combined Chemotherapy in Metastatic Colorectal Cancer

Purpose: Many reports about efficacy of cetuximab in the prolongation of survival have been published. Especially, the combination of cetuximab and FOLFIRI has a high activity even in prior irinotecan refractory metastatic colorectal cancer (mCRC). Beside small number of patients, we are trying to evaluate the efficacy and safety of cetuximab combined with FOLFIRI for patients who prior irinotecan chemotherapy had failed. Methods: A retrospective analysis of 26 patients treated with cetuximab with FOLFIRI from July 2006 to August 2007 was done. All patients had already been treated with FOLFIRI chemotherapy in 1st line or 2nd line regimens for mCRC. The initial dose of cetuximab was 400 mg/m2 at the 1st week, after which the dose was 250 mg/m2 weekly plus FOLFIRI biweekly. We defined 1 cycle as 8 weeks, and the responses were evaluated at week 8. Results: The median follow-up period was 6.2 (1.1∼13.9) months. After 8 weeks, 50% of the patients had a partial response, and the disease control rate was 57.5%. The median time to progression was 3 months. EGFR expression and tumor response had no correlation (P=0.07). Skin reaction and tumor response (median time to progression) had a significant correlation (P= 0.022). Cetuximab did not increase the toxicity associated with FOLFIRI, except for an acneiform rash. Conclusions: Cetuximab combined with FOLFIRI chemotherapy was effective in treating mCRC patients after FOLFIRI regimen chemotherapy.