Regorafenib (BAY 73-4506) in advanced colorectal cancer: a phase I study

[Bacterial outer membrane vesicles as nano carriers to study immunological activities]

Objective: To prepare a nano-carrier based on combining bacterial outer membrane vesicles (OMV) with three block polymer pluronic F127 (PEO100-PPO65-PEO100) (OMV-F127) and to investigate its immunological activity. Methods: Attenuated salmonella (sal) was cultivated. OMV were separated by centrifugal ultrafiltration or ultrasonication, and OMV-F127 was prepared by mechanical extrudation method. The protein contents and compositions were tested with BCA and SDS-PAGE; the morphology of OMV, F127 and OMV-F127 were observed with FM and TEM; the particle sizes and their zeta potential were determined with DLS. Mouse macrophage RAW246.7 cells were treated with OMV-F127 (50 μg/mL, 100 μg/mL) in vitro, and the concentrations of IL-12, TNF-α and IFN-γ in culture supernatant were measured with ELISA kits. Results: The contents of protein in separated OMV by centrifugal ultrafiltration and ultrasonication were 2.8 mg/mL and 2.7 mg/mL, respectively. SDS-PAGE showed the marker protein OmpF/C in OMV. Under the FM and TEM, ball-like structure of F127 and OMV-F127 was observed. Size analysis revealed that the diameters of OMV, F127 and OMV-F127 were 72±2 nm, 90±3 nm and 92±2 nm, respectively. ELISA tests revealed that OMV-F127 significantly stimulated the secretion of IL-12, TNF-α and IFN-γ in RAW246.7 cells. Conclusion: A nano-carrier based on bacterial outer membrane vesicles has been prepared, which can stimulate the secretion of cytokines and may have immunomodulatory effects.

Radiological imaging markers predicting clinical outcome in patients with metastatic colorectal carcinoma treated with regorafenib: post hoc analysis of the CORRECT phase III trial (RadioCORRECT study)

OBJECTIVE

To identify imaging markers predicting clinical outcomes to regorafenib in metastatic colorectal carcinoma (mCRC).

METHODS

The RadioCORRECT study is a post hoc analysis of a cohort of patients with mCRC treated within the phase III placebo-controlled CORRECT trial of regorafenib. Baseline and week 8 contrast-enhanced CT were used to assess response by RECIST 1.1, changes in the sum of target lesion diameters (ΔSTL), lung metastases cavitation and liver metastases density. Primary and secondary objectives were to develop ex novo univariable and multivariable models to predict overall survival (OS) and progression-free survival (PFS), respectively.

RESULTS

202 patients were enrolled, 134 (66.3%) treated with regorafenib and 68 (33.7%) with placebo. In the univariate analysis, PFS predictors were lung metastases cavitation at baseline (HR 0.50, 95% CI 0.27 to 0.92, p=0.03) and at week 8 (HR 0.58, 95% CI 0.36 to 0.93, p=0.02). Baseline cavitation (HR 0.23, 95% CI 0.08 to 0.66, p=0.007), RECIST 1.1 (HR 0.23, 95% CI 0.14 to 0.4, p <0.0001) and ΔSTL (HR 1.16, 95% CI 1.06 to 1.27, p=0.002) predicted OS. We found an increase of 9% of diameter as the best threshold for discriminating OS (HR 2.64, 95% CI 1.61 to 4.34, p <0.001). In the multivariate analysis, baseline and week 8 cavitation remained significant PFS predictors. Baseline cavitation, RECIST 1.1 and ΔSTL remained predictors of OS in exploratory multivariable models. Assessment of liver metastases density did not predict clinical outcome.

CONCLUSIONS

RECIST 1.1 and ΔSTL predict favourable outcome to regorafenib. In contrast to liver metastases density that failed to be a predictor, lung metastases cavitation represents a novel radiological marker of favourable outcome that deserves consideration.

Characterization of degradation products of regorafenib by LC-QTOF-MS and NMR spectroscopy: investigation of rearrangement and odd-electron ion formation during collision-induced dissociations under ESI-MS/MS

Characterization of degradation products of regorafenib by LC-QTOF-MS and NMR.

Recent Developments in Regorafenib Treatment for Gastrointestinal Cancers: Presentations at the Meeting of the European Society for Medical Oncology (ESMO) Congress 2016

The European Society for Medical Oncology (ESMO) Congress was held in Copenhagen, Denmark from 7th–11th October 2016. The use of the promiscuous multikinase inhibitor regorafenib (Stivarga®, BAY 73-4506) in the treatment of cancers of the gastrointestinal (GI) tract was strongly featured at this meeting. Regorafenib targets multiple kinases involved in oncogenesis and angiogenesis, and is US Food and Drug Administration (FDA)-approved for the treatment of advanced metastatic colorectal cancer and GI stromal tumours, following progression on standard therapies. In this review, we summarise the results of completed clinical trials on the use of regorafenib alone or in combination with other therapies for the treatment of GI cancers. We highlight the results of the Phase III RESORCE study which demonstrated the efficacy of regorafenib as a second-line therapy in patients with advanced hepatocellular carcinoma who have progressed on sorafenib. We review some promising preliminary data on the use of regorafenib in other GI cancers, such as gastric cancer, oesophageal cancer, pancreatic cancer, and soft tissue carcinomas, and provide a brief overview of ongoing and planned trials. Finally, we discuss the incidence and management of regorafenib-related toxicities and summarise attempts to identify predictive biomarkers of regorafenib sensitivity.

New chemical treatment options in second-line hepatocellular carcinoma: what to do when sorafenib fails?

INTRODUCTION

There have been no therapies available for patients who experience disease progression after sorafenib treatment. Regorafenib inhibits multiple kinases involved in tumor proliferation and neoangiogenesis, which has produced a survival benefit in hepatocellular carcinoma (HCC) after sorafenib failure. Other active candidate agents are c-Met inhibitors and immune checkpoint inhibitors. Areas covered: This paper presents an updated summary of the preclinical and clinical experience with regorafenib, c-Met inhibitors (tivantinib, cabozantinib and tepotinib), and a checkpoint inhibitor (nivolumab, pembrolizumab) in HCC. The reported data were obtained from abstracts of international conferences and journal articles published up to August 2016 and found in a PubMed search. Expert opinion: Based on favorable data from preclinical and clinical trials, regorafenib, c-Met inhibitor, and checkpoint inhibitors are promising agents for HCC after sorafenib failure. However, further efforts to maximize the survival benefit and minimize adverse events of these drugs in the treatment of HCC are still necessary. Additionally, searching for predictors of good responders could allow these new drugs to be applied in personalized treatments of HCC.

Novel investigational therapies for treating biliary tract carcinoma

INTRODUCTION

Cholangiocarcinoma (CCA) is an epithelial cell malignancy arising from bile ducts and/or peribiliary glands. Even though it is considered as a rare neoplasm, its incidence is raising, particularly in developed countries. Prognosis is generally poor with few patients who present the inclusion criteria for surgery (the mainstay treatment for this tumour). Several genetic alterations potentially driving tumour progression have been described, representing a possible target for new compounds. Areas covered: A clinical trial search in Clinicaltrials.gov encompassing a literature search in PubMed and ASCO/ESMO Websites was undertaken in March 2016. Expert opinion: Notwithstanding a large number of drug tested, results are still disappointing. The main reasons could be the low number of patients enrolled in trials, and the lack of a patient selection based on the biological profile of the tumours. Potential active drugs could have been discharged simply because beneficial in a particular subgroup of patients and not in un unselected population. The future direction of the research should consider biomarker evaluation in order to describe the genetic alteration/s that drive tumour progression and aggressiveness and the mechanisms of drug resistance. Finally, it will be of great interest to consider the results of immunotherapy whenever available.

Regorafenib induced severe toxic hepatitis: characterization and discussion

BACKGROUND

Regorafenib is the first small-molecule multikinase inhibitor which showed survival benefits in pretreated metastatic colorectal cancer (mCRC) patients. Besides classical adverse events of this drug class, hepatotoxicity has been described as a frequent side effect.

MATERIAL AND METHODS

Patients with refractory mCRC treated with regorafenib in our institution were reviewed. Severe treatment-related liver toxicity was investigated. Clinical history, liver histology and genetic assessment (sequence analysis) of cytochrome P3A4 (CYP3A4) and uridine diphosphate-glucuronosyltransferase 1A9 (UGT1A9) involved in regorafenib metabolization were here reported for patients with severe hepatotoxicity.

RESULTS

Among the 93 reviewed patients, 3 presented severe and icteric toxic hepatitis which was fatal for 1 patient. Histopathological liver lesions were different depending on the onset of hepatotoxicity (acute or subacute): acinar zone 3 necrosis in case of acute symptoms, and portal tract inflammation with porto-central bridging and fibrosis in the delayed presentation. None of the patients had CYP3A4 gene mutations. Similar polymorphisms in UGT1A9 gene promoter region (UGT1A9 variant -118T_9>10 [rs3832043]) were found in both patients who presented acute hepatitis. Moreover, it appears retrospectively that both of them already experienced significant toxicity under irinotecan-based chemotherapy.

CONCLUSION

This is the first report of severe hepatotoxicity with available liver histology and genetic assessment of enzymes involved in regorafenib metabolization. This report also reminds the importance of close liver tests monitoring during regorafenib treatment.

Pharmacologic activity and pharmacokinetics of metabolites of regorafenib in preclinical models

Regorafenib is an orally administered inhibitor of protein kinases involved in tumor angiogenesis, oncogenesis, and maintenance of the tumor microenvironment. Phase III studies showed that regorafenib has efficacy in patients with advanced gastrointestinal stromal tumors or treatment‐refractory metastatic colorectal cancer. In clinical studies, steady‐state exposure to the M‐2 and M‐5 metabolites of regorafenib was similar to that of the parent drug; however, the contribution of these metabolites to the overall observed clinical activity of regorafenib cannot be investigated in clinical trials. Therefore, we assessed the pharmacokinetics and pharmacodynamics of regorafenib, M‐2, and M‐5 in vitro and in murine xenograft models. M‐2 and M‐5 showed similar kinase inhibition profiles and comparable potency to regorafenib in a competitive binding assay. Inhibition of key target kinases by all three compounds was confirmed in cell‐based assays. In murine xenograft models, oral regorafenib, M‐2, and M‐5 significantly inhibited tumor growth versus controls. Total peak plasma drug concentrations and exposure to M‐2 and M‐5 in mice after repeated oral dosing with regorafenib 10 mg/kg/day were comparable to those in humans. In vitro studies showed high binding of regorafenib, M‐2, and M‐5 to plasma proteins, with unbound fractions of ~0.6%, ~0.9%, and ~0.4%, respectively, in murine plasma and ~0.5%, ~0.2%, and ~0.05%, respectively, in human plasma. Estimated free plasma concentrations of regorafenib and M‐2, but not M‐5, exceeded the IC₅₀ at human and murine VEGFR2, suggesting that regorafenib and M‐2 are the primary contributors to the pharmacologic activity of regorafenib in vivo.

Targeting angiogenesis in gastrointestinal tumors: current challenges

Colorectal cancer (CRC) is one of the few cancers where screening modalities are standardized, but it still remains the third leading cause of cancer related mortality. For more than a decade now, the approval of anti-angiogenic therapy has led to an increase in the rate of overall survival (OS) of patients with advanced colon cancer. The drawback of the anti-angiogenic therapy is that their effect is short-lived and many patients progress through these therapies. Various mechanisms of resistance have been hypothesized, but overcoming this has been challenging. Also, there are no standardized predictive biomarkers that could aid in selecting patients who responds to the therapy upfront. This review focuses on the basis of angiogenesis, describing the approved anti-angiogenic therapies, discusses the challenges in terms of resistance to anti-angiogenic therapy and also the role of biomarkers. In the future, hopefully newer targeted therapies, immunotherapy, combination therapies and the standardization of biomarkers may result in improved outcomes and cure rates.

Elevated prothrombin time/international normalized ratio associated with concurrent administration of regorafenib and warfarin in a patient with advanced colorectal cancer

Background

Regorafenib and its metabolites may inhibit the activities of several CYP or UDP-glucuronosyltransferase isoforms, including that of CYP2C9. Therefore, pharmacological agents that are CYP2C9 substrates may show elevated circulating levels and enhanced drug efficacy when concurrently used with regorafenib. Previous studies showed that the area under the plasma concentration-time curve of warfarin, which is the substrate for CYP2C9, increased upon co-administration of regorafenib. However, there are no reports indicating that the anticoagulant effects of warfarin increased upon co-administration of regorafenib.

Case presentation

We report a case of a 76-year-old man with liver metastasis of colon cancer. He was treated with regorafenib at a dosage of 120 mg daily on days 1 to 21 every 4 weeks as a third-line therapy. He had a history of acute myocardial infarction and had taken 2 mg warfarin daily. Three weeks after the treatment began, PT/INR values markedly increased, although there was no hemorrhage. Administration of regorafenib and warfarin was discontinued, and then PT/INR rapidly decreased. Warfarin administration was restarted (0.5 mg daily) and the dose was increased up to 1.5 mg daily. The patient’s PT/INR values exhibited a tendency to increase when concurrently used with regorafenib, the dose of which was reduced to 80 mg daily on days 1 to 14 every 3 weeks at a physician's discretion.

Conclusions

The clinical course of this patient suggested that PT/INR might increase during concurrent use of warfarin and regorafenib. Therefore, PT/INR should be periodically monitored during the concurrent use of warfarin and regorafenib.

Efficacy, Safety and Cost of Regorafenib in Patients with Metastatic Colorectal Cancer in French Clinical Practice

BACKGROUND

Regorafenib is an orally administered multikinase inhibitor that has been approved for patients with chemotherapy-refractory metastatic colorectal cancer (mCRC). Even though regorafenib significantly improved survival in two international phase 3 trials (CORRECT and CONCUR), a high rate of treatment-related toxic effects and dose modifications were observed with a modest benefit. The aim of this study was to provide information concerning the efficacy, safety, and cost of regorafenib in patients with mCRC in clinical practice.

MATERIAL AND METHODS

We retrospectively reviewed patients treated with regorafenib monotherapy for unresectable mCRC in five Franche-Comté cancer hospitals (France). The primary end point was overall survival. Secondary end points were safety and descriptive cost analyses of patients treated with regorafenib in clinical practice. Another aim of this study was to assess the impact of regorafenib prescription on the risk of hospitalization in real-life practice.

RESULTS

From January 2014 to August 2014, 29 consecutive patients were enrolled. Patients were heavily pretreated and were refractory to standard chemotherapies. The primary tumor sites were the colon and the rectum for 55% and 45% of patients, respectively. Fifteen patients (51%) harbored an RAS mutation. Eastern Cooperative Oncology Group – Performance Status (PS) was 0–1 for 86% of patients and 2 for 14% of patients. Nineteen patients (66%) initially received reduced doses of 120 or 80 mg/day. The median duration of treatment was 2.5 months (range, 0.13–11.4 months). Treatment-related adverse events occurred in 86% of patients. The most frequent adverse events of any grade were fatigue (35%), diarrhea (20%), and hand–foot skin reaction (20%). Grade 3 or 4 treatment-related adverse events occurred in 10 patients (35%). Three patients (10%) were admitted to hospital due to drug-related severe adverse events. The mean cost of patient management with regorafenib for the duration of treatment was 9908 ± 8191€, and median cost was 7917€ (Interquartile range (IQR) 4469-13,042). The median overall survival was six months (95% confidence interval, five to eight months).

CONCLUSIONS

The safety and efficacy of regorafenib in heavily pretreated mCRC patients was comparable, in our study, to prospective and retrospective trials. Toxic effects were mostly manageable in an outpatient setting. Regorafenib itself represented the most important (93%) part of supported costs. Even though most side effects were manageable in an outpatient setting, severe adverse events occurred from hospitalization in 10% of patients. These data should be confirmed in a larger real-life-based cohort. Identification of predictive biomarkers is needed for mCRC patient selection for regorafenib treatment.

Single-Agent Therapies After Standard Combination Regimens

Increasingly prolonged survival in metastatic colorectal cancer has paralleled the approval of new agents alone and in combination. Most recently, several new agents have sought approval in the heavily pretreated setting, after treatment with standard chemotherapies, alone and in combination, and with anti-vascular endothelial growth factor receptor and anti-epidermal growth factor receptor (for patients with RAS wild-type tumors). These agents have included the multitargeted tyrosine kinase inhibitor (TKI), regorafenib, and the novel antimetabolite combination, TAS-102. Both of these showed improvement in progression-free survival and overall survival compared with placebo controls and were approved in the United States and the rest of the world. Benefits of treatment and toxicities are discussed. Nintedanib, another multitargeted TKI, is already approved by the European Medicines Evaluation Agency for non-small cell lung cancer and has been studied in a similar phase III trial. Results are pending. The risks and benefits of each agent are discussed.

Targeting gastrointestinal stromal tumors: the role of regorafenib

Gastrointestinal stromal tumor (GIST) is a devastating disease in the metastatic setting, but its natural history has been dramatically altered by the development of small molecule tyrosine kinase inhibitors, most notably imatinib. Although patients with advanced GIST live much longer today than they did in the past, imatinib-refractory disease remains a tremendous problem. For disease that is refractory to imatinib and sunitinib, regorafenib is an excellent option. In this review, we discuss the biology and clinical work establishing regorafenib as the standard of care for advanced GIST refractory to both imatinib and sunitinib.

Multikinase inhibitor regorafenib inhibits the growth and metastasis of colon cancer with abundant stroma

Interaction between tumor cells and stromal cells plays an important role in the growth and metastasis of colon cancer. We previously found that carcinoma-associated fibroblasts (CAFs) expressed platelet-derived growth factor receptor-β (PDGFR-β) and that PDGFR targeted therapy using imatinib or nilotinib inhibited stromal reaction. Bone marrow-derived mesenchymal stem cells (MSCs) migrate to tumor stroma and differentiate into CAFs. A novel oral multikinase inhibitor regorafenib inhibits receptor tyrosine kinases expressed on stromal cells (vascular endothelial growth factor receptor 1-3, TIE2, PDGFR-β, and fibroblast growth factors) and tumor cells (c-KIT, RET, and BRAF). These molecules are involved in tumor growth, angiogenesis, lymphangiogenesis, and stromal activation. Therefore, we examined whether regorafenib impaired the tumor-promoting effect of CAFs/MSCs. KM12SM human colon cancer cells alone or KM12SM cells with MSCs were transplanted into the cecal wall of nude mice. Co-implantation of KM12SM cells with MSCs into the cecal wall of nude mice produced tumors with abundant stromal component and promoted tumor growth and lymph node metastasis. Single treatment with regorafenib inhibited tumor growth and metastasis by inhibiting both tumor cells and stromal reaction. This tumor-inhibitory effect of regorafenib was more obvious in tumors developed by co-implanting KM12SM cells with MSCs. Our data suggested that targeting of the tumor microenvironment with regorafenib affected tumor cell-MSC interaction, which in turn inhibited the growth and metastasis of colon cancer.

Regorafenib: A Review of Its Use in Patients with Advanced Gastrointestinal Stromal Tumours

Regorafenib (Stivarga(®)) is an orally administered small molecule inhibitor of multiple protein kinases, including kinases involved in oncogenesis and tumour angiogenesis. It was initially approved for use in patients with previously treated metastatic colorectal cancer. Based on the findings of the phase III GRID clinical trial, approval for regorafenib has been expanded to include the treatment of advanced gastrointestinal stromal tumours (GISTs) following the failure of imatinib and sunitinib. In the GRID trial, regorafenib significantly improved progression-free survival and was associated with a significantly higher disease control rate than placebo. No significant between-group difference was observed in overall survival (OS) in the trial; however, the high proportion of patients who crossed over from placebo to regorafenib likely impacted the OS analysis. Regorafenib has an acceptable tolerability profile, with most adverse events being manageable with dose modification and/or supportive measures. The most commonly reported drug-related adverse events among patients receiving regorafenib in the GRID trial were hand-foot skin reaction, hypertension, diarrhoea and fatigue. In conclusion, regorafenib presents a valuable new tool in the treatment of patients with advanced GISTs following the failure of imatinib and sunitinib.

Monitoring metabolic response using FDG PET-CT during targeted therapy for metastatic colorectal cancer

Introduction

The introduction of targeted drugs has had a significant impact on the approach to assessing tumour response. These drugs often induce a rapid cytostatic effect associated with a less pronounced and slower tumoural volume reduction, thereby impairing the correlation between the absence of tumour shrinkage and the patient’s unlikelihood of benefit. The aim of the study was to assess the predictive value of early metabolic response (mR) evaluation after one cycle, and its interlesional heterogeneity to a later metabolic and morphological response assessment performed after three cycles in metastatic colorectal cancer (mCRC) patients treated with combined sorafenib and capecitabine.

Methods

This substudy was performed within the framework of a wider prospective multicenter study on the predictive value of early FDG PET-CT response assessment (SoMore study). A lesion-based response analysis was performed, including all measurable lesions identified on the baseline PET. On a per-patient basis, a descriptive 4-class response categorization was applied based upon the presence and proportion of non-responding lesions. For dichotomic response comparison, all patients with at least one resistant lesion were classified as non-responding.

Results

On baseline FDG PET-CT, 124 measurable “target” lesions were identified in 38 patients. Early mR assessments showed 18 patients (47 %) without treatment resistant lesions and 12 patients (32 %) with interlesional response heterogeneity. The NPV and PPV of early mR were 85 % (35/41) and 84 % (70/83), respectively, on a per-lesion basis and 95 % (19/20) and 72 % (13/18), respectively, on a dichotomized per-patient basis.

Conclusions

Early mR assessment performed after one cycle of sorafenib-capecitabine in mCRC is highly predictive of non-response at a standard response assessment time. The high NPV (95 %) of early mR could be useful as the basis for early treatment discontinuation or adaptation to spare patients from exposure to non-effective drugs.

Novel anti-angiogenic therapeutic strategies in colorectal cancer

INTRODUCTION

Anti-angiogenetic agents are currently the standard of care in metastatic CRC patients. Bevacizumab, aflibercept, regorafenib and recently ramucirumab have significantly improved both progression-free and overall survival in different lines of treatment. Since bevacizumab's approval, a number of novel anti-VEGF agents have been tested in preclinical and clinical models.

AREAS COVERED

This review is focused on the most recent clinical results of novel agents targeting VEGF and its receptors with a major focus on those investigated recently in clinical trials.

EXPERT OPINION

In the last 15 years, a number of new anti-angiogenetic agents have been tested. Unfortunately, most of them have demonstrated unacceptable toxicities or failed to show activity. When tested as single agents, encouraging preliminary results were reported with fruquintinib, famitinib, and nintedanib. Interesting novel mechanisms of action are also being explored: VGX-100 is a monoclonal antibody (mAb) which binds to VEGF-C, inhibiting activation of VEGFR-2 and VEGFR-3 when combined with bevacizumab; tanibirumab is a mAb which binds to VEGFR-2 and vanucizumab is a bispecific mAb binding both to VEGF-A and Angiopoietin-2. Data about the combination of these agents with chemotherapy are very encouraging, even though preliminary. However, the definition of specific predictive biomarkers remains a priority.

Comparison of the crystal structures of the potent anticancer and anti-angiogenic agent regorafenib and its monohydrate

Regorafenib {systematic name: 4-[4-({[4-chloro-3-(trifluoromethy)phenyl]carbamoyl}amino)-3-fluorophenoxy]-1-methylpyridine-2-carboxamide}, C21H15ClF4N4O3, is a potent anticancer and anti-angiogenic agent that possesses various activities on the VEGFR, PDGFR, raf and/or flt-3 kinase signaling molecules. The compound has been crystallized as polymorphic form I and as the monohydrate, C21H15ClF4N4O3·H2O. The regorafenib molecule consists of biarylurea and pyridine-2-carboxamide units linked by an ether group. A comparison of both forms shows that they differ in the relative orientation of the biarylurea and pyridine-2-carboxamide units, due to different rotations around the ether group, as measured by the C-O-C bond angles [119.5 (3)° in regorafenib and 116.10 (15)° in the monohydrate]. Meanwhile, the conformational differences are reflected in different hydrogen-bond networks. Polymorphic form I contains two intermolecular N-H...O hydrogen bonds, which link the regorafenib molecules into an infinite molecular chain along the b axis. In the monohydrate, the presence of the solvent water molecule results in more abundant hydrogen bonds. The water molecules act as donors and acceptors, forming N-H...O and O-H...O hydrogen-bond interactions. Thus, R4(2)(28) ring motifs are formed, which are fused to form continuous spiral ring motifs along the a axis. The (trifluoromethyl)phenyl rings protrude on the outside of these motifs and interdigitate with those of adjacent ring motifs, thereby forming columns populated by halogen atoms.

Targeting FGF receptors in colorectal cancer: from bench side to bed side

Successful management of advanced colorectal cancer has been a challenging job for practicing oncologists as well as a priority for the oncology research community. The better understanding of the underlying patho-biology and critical pathway targets in this disease has contributed to major developments in that direction. In this review, we will revise the different biological and clinical aspects related to the use of FGFR pathway-targeted therapies in advanced colorectal cancer with particular focus on future perspectives in that regard.

Clinical Implication of Anti-Angiogenic Effect of Regorafenib in Metastatic Colorectal Cancer

Background

Regorafenib induces distinct radiological changes that represent its anti-angiogenic effect. However, clinical implication of the changes is unclear.

Methods

Tumor attenuation as measured by Hounsfield units (HU) in contrast-enhanced computed tomography (CT) and cavitary changes of lung metastases were analyzed in association with treatment outcome of metastatic colorectal cancer patients (N = 80) treated with regorafenib in a prospective study.

Results

141 lesions in 72 patients were analyzed with HU. After 2 cycles of regorafenib, 87.5% of patients showed decrease of HU (Median change -23.9%, range -61.5%–20.7%). Lesional attenuation change was modestly associated with metabolic changes of 18-fluoro-deoxyglucose positron emission tomography-CT (Pearson’s r = 0.37, p = 0.002). Among 53 patients with lung metastases, 17 (32.1%) developed cavitary changes. There were no differences in disease control rate, progression-free survival, or overall survival according to the radiological changes. At the time of progressive disease (PD) according to RECIST 1.1, HU was lower than baseline in 86.0% (43/50) and cavitary change of lung metastasis persisted without refilling in 84.6% (11/13).

Conclusion

Regorafenib showed prominent anti-angiogenic effect in colorectal cancer, but the changes were not associated with treatment outcome. However, the anti-angiogenic effects persisted at the time of PD, which suggests that we may need to develop new treatment strategies.

The safety of regorafenib for the treatment of gastrointestinal stromal tumors

INTRODUCTION

The management of gastrointestinal stromal tumors (GIST) evolved due to effective molecularly targeted therapy with imatinib and sunitinib which are used first- and second-line, respectively. However, due to the development of resistance to those drugs in the majority of patients, the need for third-line therapy arose.

AREAS COVERED

Regorafenib, an oral multitargeted inhibitor with activity against multiple kinases including KIT, RET, RAF1, BRAF, angiogenesis (VEGFR, TIE-2) and those involved in tumor microenvironment (PDGFR and FGFR) was introduced after the successful Phase III GRID (GIST - Regorafenib In progressive Disease) clinical trial. This study showed significant improvement in progression-free survival for patients receiving regorafenib compared to placebo (4.8 months vs 0.9 months). The treatment was reasonably well tolerated, with arterial hypertension, hand-foot syndrome, diarrhea being the most common grade ≥3 adverse events, which could be managed by dose reduction and supportive treatment. The aim of this paper is to describe, assess and advise on the safety of regorafenib as third-line therapy in GIST.

EXPERT OPINION

Regorafenib has demonstrated clinical benefit in GIST patients after progression on prior treatment with at least imatinib/sunitinib and currently it is the approved standard third-line option in therapy of advanced GIST. The safety profile is similar to other multikinase inhibitors with anti-VEGFR activity and is manageable.

Molecular profiling in the treatment of colorectal cancer: focus on regorafenib

Metastatic colorectal cancer (mCRC) is a highly heterogeneous disease. Its treatment outcome has been significantly improved over the last decade with the incorporation of biological targeted therapies, including anti-EGFR antibodies, cetuximab and panitumumab, and VEGF inhibitors, bevacizumab, ramucirumab, and aflibercept. The identification of predictive biomarkers has further improved the survival by accurately selecting patients who are most likely to benefit from these treatments, such as RAS mutation profiling for EGFR antibodies. Regorafenib is a multikinase inhibitor currently used as late line therapy for mCRC. The molecular and genetic markers associated with regorafenib treatment response are yet to be characterized. Here, we review currently available clinical evidence of mCRC molecular profiling, such as RAS, BRAF, and MMR testing, and its role in targeted therapies with special focus on regorafenib treatment.

Acute liver failure and seizures as a consequence of regorafenib exposure in advanced rectal cancer

Background

Regorafenib is a multi-targeted tyrosine kinase inhibitor approved for use in refractory colorectal cancer. We report the first case of seizures secondary to acute liver failure, shortly after initiation of regorafenib in a patient with advanced rectal carcinoma.

Case presentation

A 64 year-old Caucasian female presented with confusion and generalized tonic–clonic seizures, 5 days after initiation of regorafenib for advanced rectal cancer. Investigations revealed significant elevations in bilirubin and alanine aminotransferase. No other cause for seizures and liver dysfunction were found. After interruption of regorafenib, no further seizures occurred, the symptoms of confusion resolved and liver function returned to normal.

Conclusions

We report the first case of regorafenib-induced acute liver failure resulting in seizures. We suggest early monitoring for side effects, both clinically and biochemically after initiation of regorafenib.

Update on Anti-Angiogenesis Therapy in Colorectal Cancer

Angiogenesis is a complex biologic process critical to growth and proliferation of colorectal cancer. The safety and efficacy of various anti-angiogenic agents have been investigated in many treatment settings. Bevacizumab, an anti-vascular endothelial growth factor agent, has efficacy in both the first-line setting and beyond progression in metastatic colorectal cancer. The decoy vascular endothelial growth factor receptor aflibercept has been approved in combination with 5-fluorouracil, leucovorin and irinotecan-based chemotherapy in metastatic colorectal cancer patients whose disease has progressed on a prior oxaliplatin-based chemotherapy regimen. The multikinase inhibitor regorafenib is modestly effective in the refractory colorectal cancer setting but confers significant toxicity. Ramucirumab, an anti-vascular endothelial growth factor receptor 2 molecule, has efficacy in combination with 5-fluorouracil, leucovorin and irinotecan after disease progression on a first-line bevacizumab-, oxaliplatin- and fluoropyrimidine-containing regimen. Questions regarding optimal treatment setting, predictive biomarkers of response, and cost effectiveness of these anti-angiogenic agents and others are as yet unanswered.

Management of regorafenib-related toxicities: a review

Regorafenib (Stivarga, BAY 73-4506; Bayer Pharma AG, Berlin, Germany) is an oral multikinase inhibitor that targets the angiogenic tumor microenvironment and oncogenic kinases including vascular endothelial growth factor receptor 2 (VEGFR2), VEGFR1, VEGFR3, fibroblast growth factor receptor 1 (FGFR1), RAF, KIT, RET and BRAF. Its antiangiogenic effect is greater than that of its related drug, sorafenib. Regorafenib has been approved by the US Food and Drug Administration (FDA) for the treatment of metastatic colorectal cancer (mCRC) in patients who have failed treatment with fluoropyrimidine, oxaliplatin and irinotecan based chemotherapy, an anti-VEGF therapy and, if KRAS wild type, an anti-EGFR therapy. The FDA based this approval on data from the CORRECT trial, which showed the efficacy of regorafenib compared with placebo. The most common grade 3-4 adverse reactions with the drug are hand foot skin reactions (HFSR), diarrhea, hypertension and fatigue. This review discusses the efficacy data, and the incidence and management of regorafenib's toxicities.

A phase I open-label trial evaluating the cardiovascular safety of regorafenib in patients with advanced cancer

PURPOSE

To characterize the cardiovascular safety profile of regorafenib in patients with advanced cancer.

METHODS

Patients received regorafenib 160 mg/day for 21 days followed by a 7-day break. The primary endpoint was the change from baseline in QTcF at the regorafenib t(max) (Day 21, Cycle 1 or 2) and changes in left ventricular ejection fraction (LVEF) from baseline on Cycle 2, Day 21. Secondary objectives were pharmacokinetics, safety, anti-tumor activity and effects on electrocardiogram intervals. QT intervals were corrected using the methods of Fridericia (QTcF) and Bazett (QTcB). LVEF was assessed by multigated acquisition scanning.

RESULTS

Fifty-three patients were enrolled, and all received at least one dose of regorafenib 160 mg. Twenty-five patients received regorafenib for 21 days without dose reduction. The mean change from baseline in QTcF at t(max) was (-)2 ms (90 % CI -8, 3). No patient experienced a change from baseline in QTcF > 60 ms, and two had QTcF changes between 30 and 60 ms. No patient had a QTcF or QTcB > 480 ms. In 27 patients who received at least 80 mg of regorafenib, the mean change from baseline in LVEF% ± SD was 1.7 ± 7.8. In 14 patients without a dose reduction, the mean change from baseline in LVEF% was (-)0.1 ± 8.6 at Cycle 2, Day 21. Four patients experienced a LVEF decrease between 10 and 20 %.

CONCLUSION

The effects of regorafenib on the QT/QTc interval and LVEF were modest and unlikely to be of clinical significance in the setting of advanced cancer therapy.

[Anti-angiogenic treatments in metastatic colorectal cancer: Does a continuous angiogenic blockade make sense?]

Ten years after the approval of bevacizumab in colorectal cancer patients, results from ML18147 and CORRECT studies have recently demonstrated the possibility to target angiogenesis in patients previously exposed to anti-VEGF. An increasing number of anti-angiogenic treatments are now available, however, no biomarker has yet succeeded in rationalizing our therapeutic strategies. Nevertheless, several lessons have been learned from preclinical and pivotal clinical studies. The first clinical trials demonstrated a survival benefit, adding VEGFA targeting monoclonal antibodies to chemotherapy in metastatic colorectal cancer patients (AVF2107, ECOG 3200). Many phase III clinical trials confirmed the interest of this strategy, in combination with chemotherapies containing irinotecan, oxaliplatin, or with 5-fluorouracil in monotherapy. To date, such results have not been reproduced with tyrosine kinase inhibitors targeting the angiogenesis pathways, with an increasing rate of chemotherapy related toxicities. Clinical trials performed in the adjuvant setting (AVANT, NSABPC08) failed to demonstrate any efficacy of the anti-VEGFA treatments on the micrometastatic disease, encouraging its prescription in the unresectable cases. On the other hand, a continuous inhibition of angiogenesis during the course of the metastatic disease was shown to be feasible and to extend colon cancer patient's survival in two recent randomized trials. For these patients, the continuation of bevacizumab beyond progression in first line improves overall survival. Lastly, results achieved by the CORRECT and CONCUR studies demonstrated that anti-angiogenics might be effective in colorectal cancers resistant to chemotherapy. This review presents the main results of preclinical and clinical studies sustaining the prescription of anti-angiogenics in metastatic colorectal cancers. The future challenge is to promote the development of biomarkers to enable the stratification of the different therapeutic strategies.

Anti-angiogenic agents in metastatic colorectal cancer

Colorectal cancer (CRC) is a major public health concern being the third leading cause of cancer mortality in the United States. The availability of better therapeutic options has led to a decline in cancer mortality in these patients. Surgical resection should be considered in all stages of the disease. The use of conversion therapy has made surgery a potentially curative option even in patients with initially unresectable metastatic disease. In this review we discuss the role of various anti-angiogenic agents in patients with metastatic CRC (mCRC). We describe the mechanism of action of these agents, and the rationale for their use in combination with chemotherapy. We also review important clinical studies that have evaluated the safety and efficacy of these agents in mCRC patients. Despite the discovery of several promising anti-angiogenic agents, mCRC remains an incurable disease with a median overall survival of just over 2 years in patients exposed to all available treatment regimens. Further insights into tumor biology and tumor microenvironment may help improve outcomes in these patients.

KRAS exon 2 mutations influence activity of regorafenib in an SW48-based disease model of colorectal cancer

ABSTRACT 

Aim: To investigate the impact of KRAS mutation variants on the activity of regorafenib in SW48 colorectal cancer cells. Materials & methods: Activity of regorafenib was evaluated in isogenic SW48 KRAS wild-type (WT) and mutant cells. Subcutaneous xenografts (KRAS WT and G12C mutant variants) in NOD/SCID mice were analyzed to elucidate the effect of regorafenib treatment in vivo. Results: Compared with KRAS WT cells, all mutant variants seemed associated with some degree of resistance to regorafenib-treatment in vitro. In vivo, activation of apoptosis (TUNEL) and reduction of proliferation (Ki67) after treatment with regorafenib were more pronounced in KRAS WT tumors as compared with G12C variants. Conclusion: In SW48 cells, exon 2 mutations of the KRAS gene may influence antitumor effects of regorafenib.

Primary and Acquired Resistance of Colorectal Cancer to Anti-EGFR Monoclonal Antibody Can Be Overcome by Combined Treatment of Regorafenib with Cetuximab

PURPOSE

In colorectal cancer, the activation of the intracellular RAS-RAF and PIK3CA-AKT pathways has been implicated in the resistance to anti-EGFR mAbs. We have investigated the role of regorafenib, an oral multikinase inhibitor, in combination with cetuximab, an anti-EGFR mAb, to overcome anti-EGFR resistance.

EXPERIMENTAL DESIGN

We have tested, in vitro and in vivo, the effects of regorafenib in a panel of human colorectal cancer cell lines with a KRAS mutation (SW480, SW620, HCT116, LOVO, and HCT15) or with a BRAF mutation (HT29), as models of intrinsic resistance to cetuximab treatment, and in two human colorectal cancer cell lines (GEO and SW48) that are cetuximab-sensitive, as well as in their derived cells with acquired resistance to cetuximab (GEO-CR and SW48-CR).

RESULTS

Treatment with regorafenib determined a dose-dependent growth inhibition in all colorectal cancer cell lines. The combined treatment with cetuximab and regorafenib induced synergistic antiproliferative and apoptotic effects in cetuximab-resistant cell lines by blocking MAPK and AKT pathways. Nude mice were injected s.c. with HCT116, HCT15, GEO-CR, and SW48-CR cells. The combined treatment caused significant tumor growth inhibition. Synergistic antitumor activity of regorafenib plus cetuximab was also observed in an orthotopic colorectal cancer model of HCT116 cells. In particular, the combined treatment induced a significant tumor growth inhibition in the primary tumor site (cecum) and completely prevented metastasis formation.

CONCLUSIONS

The combined treatment with cetuximab and regorafenib could be a strategy to overcome resistance to anti-EGFR therapies in metastatic colorectal cancer patients.

Randomized phase III trial of regorafenib in metastatic colorectal cancer: analysis of the CORRECT Japanese and non-Japanese subpopulations

BACKGROUND

In the international, phase III, randomized, double-blind CORRECT trial, regorafenib significantly prolonged overall survival (OS) versus placebo in patients with metastatic colorectal cancer (mCRC) that had progressed on all standard therapies. This post hoc analysis evaluated the efficacy and safety of regorafenib in Japanese and non-Japanese subpopulations in the CORRECT trial.

METHODS

Patients were randomized 2 : 1 to regorafenib 160 mg once daily or placebo for weeks 1-3 of each 4-week cycle. The primary endpoint was OS. Outcomes were assessed using descriptive statistics.

RESULTS

One hundred Japanese and 660 non-Japanese patients were randomized to regorafenib (n = 67 and n = 438) or placebo (n = 33 and n = 222). Regorafenib had a consistent OS benefit in the Japanese and non-Japanese subpopulations, with hazard ratios of 0.81 (95 % confidence interval [CI] 0.43-1.51) and 0.77 (95 % CI 0.62-0.94), respectively. Regorafenib-associated hand-foot skin reaction, hypertension, proteinuria, thrombocytopenia, and lipase elevations occurred more frequently in the Japanese subpopulation than in the non-Japanese subpopulation, but were generally manageable.

CONCLUSION

Regorafenib appears to have comparable efficacy in Japanese and non-Japanese subpopulations, with a manageable adverse-event profile, suggesting that this agent could potentially become a standard of care in patients with mCRC.

Regorafenib-associated hand-foot skin reaction: practical advice on diagnosis, prevention, and management

Regorafenib is an oral multikinase inhibitor licensed for use in gastrointestinal cancers. In clinical trials, regorafenib showed a consistent toxicity profile, including clinically significant hand–foot skin reaction (HFSR). Treatment modifications and symptomatic measures, as recommended in this review, can be used to manage HFSR and help patients to continue treatment at an optimal dose.

Background

Regorafenib is an orally available, small-molecule multikinase inhibitor with international marketing authorizations for use in colorectal cancer and gastrointestinal stromal tumors. In clinical trials, regorafenib showed a consistent and predictable adverse-event profile, with hand–foot skin reaction (HFSR) among the most clinically significant toxicities. This review summarizes the clinical characteristics of regorafenib-related HFSR and provides practical advice on HFSR management to enable health care professionals to recognize, pre-empt, and effectively manage the symptoms, thereby allowing patients to remain on active therapy for as long as possible.

Design

This review is based on a systematic literature search of the PubMed database (using synonyms of HFSR, regorafenib, and skin toxicities associated with targeted therapies or cytotoxic chemotherapy). However, as this search identified very few articles, the authors also use their clinical experience as oncologists and dermatologists managing patients with treatment-related HFSR to provide recommendations on recognition and management of HFSR in regorafenib-treated patients.

Results

Regorafenib-related HFSR is similar to that seen with other multikinase inhibitors (e.g. sorafenib, sunitinib, cabozantinib, axitinib, and pazopanib) but differs from the hand–foot syndrome seen with cytotoxic chemotherapies (e.g. fluoropyrimidines, anthracyclines, and taxanes). There have been no controlled trials of symptomatic management of regorafenib-related HFSR, and limited good-quality evidence from randomized clinical trials of effective interventions for HFSR associated with other targeted therapies. Recommendations on prevention and management of regorafenib-related HFSR in this review are therefore based on the expert opinion of the authors (dermatologists and oncologists with expertise in the management of treatment-related skin toxicities and oncologists involved in clinical trials of regorafenib) and tried-and-tested empirical experience with other multikinase inhibitors and cytotoxic chemotherapies.

Conclusions

As recommended in this review, treatment modifications and supportive measures to prevent, reduce, and manage HFSR can allow patients to continue regorafenib at the optimal dose to derive benefit from treatment.

Regorafenib plus best supportive care versus placebo plus best supportive care in Asian patients with previously treated metastatic colorectal cancer (CONCUR): a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

In the international randomised phase 3 CORRECT trial (NCT01103323), regorafenib significantly improved overall survival versus placebo in patients with treatment-refractory metastatic colorectal cancer. Of the 760 patients in CORRECT, 111 were Asian (mostly Japanese). This phase 3 trial was done to assess regorafenib in a broader population of Asian patients with refractory metastatic colorectal cancer than was studied in CORRECT.

METHODS

In this randomised, double-blind, placebo-controlled, parallel-group, phase 3 trial done in 25 hospitals in mainland China, Hong Kong, South Korea, Taiwan, and Vietnam, we recruited Asian patients aged 18 years or older with progressive metastatic colorectal cancer who had received at least two previous treatment lines or were unable to tolerate standard treatments. Patients had to have an Eastern Cooperative Oncology Group performance status of 0 or 1, life expectancy of at least 3 months, and adequate bone marrow, liver, and renal function, without other uncontrolled medical disorders. We randomly allocated patients (2:1; with a computer-generated unicentric randomisation list [prepared by the study funder] and interactive voice response system; block size of six; stratified by metastatic site [single vs multiple organs] and time from diagnosis of metastatic disease [<18 months vs ≥18 months]) to receive oral regorafenib 160 mg once daily or placebo on days 1-21 of each 28 day cycle; patients in both groups were also to receive best supportive care. Participants, investigators, and the study funder were masked to treatment assignment. The primary endpoint was overall survival, and we analysed data on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, number NCT01584830.

FINDINGS

Between April 29, 2012, and Feb 6, 2013, we screened 243 patients and randomly assigned 204 patients to receive either regorafenib (136 [67%]) or placebo (68 [33%]). After a median follow-up of 7·4 months (IQR 4·3-12·2), overall survival was significantly better with regorafenib than it was with placebo (hazard ratio 0·55, 95% CI 0·40-0·77, one-sided p=0·00016; median overall survival 8·8 months [95% CI 7·3-9·8] in the regorafenib group vs 6·3 months [4·8-7·6] in the placebo group). Drug-related adverse events occurred in 132 (97%) of 136 regorafenib recipients and 31 (46%) of 68 placebo recipients. The most frequent grade 3 or higher regorafenib-related adverse events were hand-foot skin reaction (22 [16%] of 136 patients in the regorafenib group vs none in the placebo group), hypertension (15 [11%] vs two [3%] of 68 patients in the placebo group), hyperbilirubinaemia (nine [7%] vs one [1%]), hypophosphataemia (nine [7%] vs none), alanine aminotransferase concentration increases (nine [7%] vs none), aspartate aminotransferase concentration increases (eight [6%] vs none), lipase concentration increases (six [4%] vs one [1%]), and maculopapular rash (six [4%] vs none). Drug-related serious adverse events occurred in 12 (9%) patients in the regorafenib group and three (4%) in the placebo group.

INTERPRETATION

This phase 3 trial is the second to show an overall survival benefit with regorafenib compared with placebo in patients with treatment-refractory metastatic colorectal cancer, substantiating the role of regorafenib as an important treatment option for patients whose disease has progressed after standard treatments. In this trial, preceding standard treatments did not necessarily include targeted treatments. Adverse events were generally consistent with the known safety profile of regorafenib in this setting.

FUNDING

Bayer HealthCare Pharmaceuticals.

Preliminary Safety, Pharmacokinetics, and Efficacy of Regorafenib, Cisplatin, and Pemetrexed in Patients With Advanced Nonsquamous Non-Small-Cell Lung Cancers

Regorafenib is an oral multitargeted kinase inhibitor with potent antiangiogenic activity. In this phase I trial we evaluated the safety, pharmacokinetics, and efficacy of regorafenib with cisplatin and pemetrexed for patients with advanced nonsquamous non-small-cell lung cancers (nsNSCLCs). Nine patients enrolled before premature termination of the study. Five of 9 (56%) patients had a partial response and the median progression-free survival was 7 months (range, 1.5-15.1 months). Regorafenib had acceptable tolerability and minor pharmacokinetic interactions in combination with standard doses of cisplatin and pemetrexed in patients with advanced nsNSCLCs.

BACKGROUND

The combination of bevacizumab, an antiangiogenesis agent, with cytotoxic chemotherapy improves survival in patients with advanced nonsquamous non-small-cell lung cancers (nsNSCLCs). Regorafenib is an oral multitargeted kinase inhibitor with potent antiangiogenic activity that is approved for patients with advanced colorectal cancer and gastrointestinal stromal tumors. In this phase I trial we evaluated the safety, pharmacokinetics (PK), and efficacy of regorafenib with cisplatin and pemetrexed for patients with advanced nsNSCLCs.

PATIENTS AND METHODS

Chemotherapy-naive patients with advanced nsNSCLCs were treated with regorafenib 60 mg/d continuously and cisplatin 75 mg/m(2) with pemetrexed 500 mg/m(2) once every 21 days for up to 6 cycles. Thereafter, regorafenib with or without pemetrexed could be continued as maintenance.

RESULTS

Nine patients enrolled before premature termination of the study because of slow recruitment and a change in the development strategy of regorafenib by the study sponsor. Five patients experienced at least 1 treatment-related Grade 3 adverse event. No Grade 4 or 5 toxicity occurred. Five of 9 (56%) patients had a partial response and the median progression-free survival was 7 months (range, 1.5-15.1 months). Minor PK interactions between regorafenib and chemotherapy were observed.

CONCLUSION

Regorafenib had acceptable tolerability and minor PK interactions in combination with standard doses of cisplatin and pemetrexed in patients with advanced nsNSCLCs. Encouraging activity was appreciated in chemotherapy-naive patients with advanced nsNSCLCs. However, the small number of patients treated limits conclusions that can be drawn from these results.

Regorafenib in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the GI tract and constitute less than 1% of all digestive tract tumors--the stomach is the most common site. Regorafenib is a multi-tyrosine kinase inhibitor with regulatory approvals granted for colorectal cancers and GIST. The US FDA granted approval for the use of regorafenib in February 2013 in patients with advanced GIST for those who had failed on imatinib and sunitinib. This was based on a pivotal Phase III double-blind placebo controlled randomized trial that showed that there was a significant improvement in progression-free survival for patients on regorafenib.

Regorafenib assessment in refractory advanced colorectal cancer: RegARd-C study protocol

INTRODUCTION

Regorafenib was recently approved for patients with pretreated advanced colorectal cancer (aCRC), despite a moderate improvement of the patients' outcome, and significant toxicities. Based on previous studies showing that early fluorodeoxyglucose-positron emission tomography (FDG-PET)-based metabolic response assessment (MRA) might adequately select patients unlikely to benefit from treatment, the RegARd-C trial uses early MRA to identify likely non-responders to regorafenib in a population of patients with aCRC and guide a comprehensive evaluation of genomic and epigenetic determinants of resistance to treatment.

METHODS AND ANALYSIS

RegARd-C is a multicentric prospective study. Its primary objective is to identify non-benefitters from regorafenib given at 160 mg/day, 3 weeks out of 4 in a population of patients with pretreated aCRC. Baseline PET is repeated at day 14 of the first treatment course. MRA is blinded for the investigators. Overall survival (OS) is the primary end point and will be correlated with metabolic parameters and (epi)genetic alterations assessed from tumour and serial blood samples. A target sample size of 105 evaluable patients (70 as derivation set and 35 as validation set), is considered as sufficient to validate an expected HR for OS of metabolic responders compared to metabolic non-responders significantly <1 (with 80% power and 1-sided 5% α in case of a true HR≤0.59 and a responders rate of 47%).

ETHICS AND DISSEMINATION

The study was approved by the Institut Jules Bordet's competent ethics committee and complies with the Helsinki declaration or the Belgian laws and regulations, whichever provides the greatest protection for the patient, and follows the International Conference on Harmonisation E 6 (R1) Guideline for Good Clinical Practice, reference number CPMP/ICH/135/95. The protocol and the trials results, even inconclusive, will be presented at international oncology congresses, and published in peer-reviewed journals. Genomic and epigenetic data will be made available in public open data sets.

TRIAL REGISTRATION NUMBERS

EudraCT number: 2012-005655-16; ClinicalTrials.gov number: NCT01929616.

Discovery of anilinopyrimidine-based naphthamide derivatives as potent VEGFR-2 inhibitors

Vascular endothelial growth factor receptor-2 (VEGFR-2) plays an important role in tumor angiogenesis, and inhibition of the VEGFR-2 signaling pathway has emerged as an attractive strategy for the treatment of cancer.

Regorafenib with a fluoropyrimidine for metastatic colorectal cancer after progression on multiple 5-FU-containing combination therapies and regorafenib monotherapy

We present 2 patients with metastatic colorectal cancer who had progressed despite treatment with first-line FOLFOX and second-line FOLFIRI combination chemotherapy regimens. After failing these fluoropyrimidine-based regimens, both patients received additional cytotoxic and targeted therapies with eventual disease progression. These therapies included capecitabine plus dabrafenib and trametinib, regorafenib monotherapy, and regorafenib with panitumumab. After exhausting available options, both patients were offered regorafenib with either 5-fluorouracil (5-FU) or capecitabine. These therapies are individually approved for the treatment of colorectal cancer but have not yet been studied in combination. This regimen produced stable disease in both patients with acceptable toxicity. One patient continued therapy for 17 months. Although these patients previously progressed during treatment with regorafenib, capecitabine or 5-FU, the combination had some activity in both cases of refractory metastatic colorectal cancer and may be considered in the palliative setting. In bedside-to-bench cell culture experiments performed after the clinical observations, we observed sensitivity of human colorectal cancer cell lines (N = 4) to single agent regorafenib or 5-FU and evidence of synergy with the combination therapy. Synergistic effects were noted in colorectal cancer cells with KRAS mutation, BRAF mutation, and p53 mutation, as well as mismatch repair deficient cells. Regorafenib suppressed Mcl-1 and Bcl-XL in treated cancer cells that may have contributed to the anticancer efficacy including in combination with 5-FU. The safety and efficacy of regorafenib with 5-FU or capecitabine in combination should be further investigated as a therapy for patients with refractory metastatic colorectal cancer, including individuals who had progressed on regorafenib monotherapy.