Regorafenib: a review of its use in previously treated patients with progressive metastatic colorectal cancer

Association between albumin-bilirubin grade and plasma trough concentrations of regorafenib and its metabolites M-2 and M-5 at steady-state in Japanese patients

The aim of the present study was to determine whether the trough plasma concentrations (C0) of regorafenib and its metabolites, the N-oxide metabolite (M-2) and the desmethyl N-oxide metabolite (M-5), in 21 patients receiving regorafenib therapy were affected by albumin-bilirubin (ALBI) grade. Regorafenib was administered at dosages ranging from 40 to 160 mg once daily on a 3-week-on, 1-week-off cycle. C0 values of regorafenib and its major metabolites were measured by high-performance liquid chromatography on day 8 after treatment initiation. The C0 values of regorafenib and metabolites M-2 and M-5 were significantly lower in patients with ALBI grade 2 as compared with grade 1 (P = 0.023, 0.003 and 0.017, respectively). The total C0 of regorafenib and its metabolites was significantly higher in ALBI grade 1 patients relative to grade 2 (3.489 μg/mL vs. 1.48 μg/mL; P = 0.009). The median relative dose intensity (RDI) of patients categorized as ALBI grade 2 was significantly lower than that of grade 1 patients (21.9% vs. 62.9%; P = 0.006). In 15 colorectal cancer patients among the total 21 patients, patients with ALBI grade 2 (n = 9) had a significantly shorter median overall survival time than patients with grade 1 (n = 6; P = 0.013). Administering a low dose of regorafenib to patients with ALBI grade 2 reduces the RDI of regorafenib and lowers treatment efficacy, as an appropriate C0 of regorafenib is not maintained. Monitoring the C0 of regorafenib regularly is necessary to guide dose adjustment.

Current Targeted Therapy for Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer and the second leading cause of cancer deaths worldwide. Surgery or surgery plus radiotherapy and/or chemotherapy for patients with metastatic CRC (mCRC) were accepted as the main therapeutic strategies until the early 2000s, when targeted drugs, like cetuximab and bevacizumab, were developed. The use of targeted drugs in clinical practice has significantly increased patients' overall survival. To date, the emergence of several types of targeted drugs has opened new possibilities and revealed new prospects for mCRC treatment. Therapeutic strategies are continually being updated to select the most suitable targeted drugs based on the results of clinical trials that are currently underway. This review discusses the up-to date molecular evidence of targeted therapy for mCRC and summarizes the Food and Drug Administration-approved targeted drugs including the results of clinical trials. We also explain their mechanisms of action and how these affect the choice of a suitable targeted therapy.

Oral drugs in the treatment of metastatic colorectal cancer

Colorectal cancer (CRC) is one of the most common forms of cancer, with an estimated 1.36 million new cases and almost 700,000 deaths annually. Approximately 21% of patients with CRC have metastatic disease at diagnosis. The objective of this article is to review the literature on the efficacy and safety of oral drugs available for the treatment of metastatic colorectal cancer (mCRC). Several such drugs have been developed, and fluoropyrimidines are the backbone of chemotherapy in this indication. They exert their antitumour activity by disrupting the synthesis and function of DNA and RNA. Oral fluoropyrimidines include prodrugs capecitabine, tegafur, eniluracil/5-fluorouracil, tegafur/uracil, tegafur/gimeracil/oteracil and trifluridine/tipiracil (FTD/TPI). Oral drugs offer several advantages over injectable formulations, including convenience, flexibility, avoidance of injection-related adverse events (AEs) and, in some circumstances, lower costs. However, oral drugs may not be suitable for patients with gastrointestinal obstruction or malabsorption, they may result in reduced treatment adherence and should not be co-administered with drugs that interfere with absorption or hepatic metabolism. Oral fluoropyrimidines such as capecitabine, as monotherapy or in combination with oxaliplatin, irinotecan or bevacizumab, are as effective as intravenous 5-fluorouracil (5-FU) in first-line treatment of mCRC. Other oral fluoropyrimidines, such as FTD/TPI, are effective in patients with mCRC who are refractory, intolerant or ineligible for 5-FU. In addition, oral fluoropyrimidines are used in adjuvant treatment of mCRC. Regorafenib is an oral multikinase inhibitor used in patients in whom several previous lines of therapy have failed. Frequent AEs associated with oral drugs used in the treatment of CRC include hand-foot syndrome and gastrointestinal and haematological toxicities.

Quality-adjusted survival in patients with metastatic colorectal cancer treated with fruquintinib in the FRESCO trial

Aim: To assess whether the survival benefit of fruquintinib is quality-adjusted. Materials & methods: Data of 416 metastatic colorectal cancer patients from the Phase III FRESCO trial were used. The Quality-adjusted Time Without Symptoms or Toxicity (Q-TWiST) analysis assessed the quality-adjusted survival benefit of fruquintinib versus placebo, accounting for freedom from symptomatic disease and from severe side effects of treatment. Results: Fruquintinib significantly improved patients' Q-TWiST (difference: 2.23 [1.41, 3.04] months) versus placebo. The Q-TWiST gain was 28.3% in the base case and ranged from 16.7 to 39.9% in the threshold analysis, favoring fruquintinib. The Q-TWiST benefit was observed in fruquintinib-treated patients regardless of prior targeted therapy. Conclusion: Fruquintinib provides a clinically meaningful quality-adjusted survival benefit versus placebo as a third-line treatment for metastatic colorectal cancer patients.

The inhibition of colorectal cancer growth by the natural product macrocarpal I

BACKGROUND

Presently, few small molecule compounds are used as targeted therapy drugs in the treatment of colorectal cancer (CRC). It is important to identify new small molecule compounds, which can be used in the treatment of CRC.

METHODS

In this study, we selected four protein molecules as drug targets: PRL-3 (Phosphatase of regenerating liver 3), CLIC4 (Chloride intracellular channel 4), THBS2 (Thrombospondin 2), and BGN (Biglycan). These protein molecules were associated with the growth and metastasis of CRC cells. Small molecular compounds were screened on the basis of their target structures. Thus, five small molecule compounds were screened from each target structure, and three small molecule compounds (macrocarpal I, sildenafil, and neoandrographolide) were found to bind with two drug targets at the same time. Further experiments revealed that the inhibition rate of macrocarpal I was the highest in CRC cells. Therefore, we determined the effects of macrocarpal I on proliferation, apoptosis, cytoskeleton of CRC cells, and subcutaneous tumorigenesis in nude mice. Furthermore, RNA-seq analysis was performed to determine the molecular mechanism through which macrocarpal I inhibited the progression of CRC.

RESULTS

We found that macrocarpal I could effectively inhibit proliferation, colony formation of CRC cells, and subcutaneous tumorigenesis in nude mice. Moreover, it also destroyed the cytoskeleton of CRC cells and promoted apoptosis. The effects on kinase activity, cytoskeleton, and DNA repair is the mechanism of macrocarpal I to inhibiting CRC growth.

CONCLUSION

Macrocarpal I is a small molecule compound that can effectively inhibit the progression of CRC. Thus, macrocarpal I is a therapeutic compound that shows promising results in the treatment of advanced CRC.

Targeted therapy for colorectal cancer metastases: A review of current methods of molecularly targeted therapy and the use of tumor biomarkers in the treatment of metastatic colorectal cancer

Despite recent advances in the management of colorectal cancer, metastatic disease remains challenging, and patients are rarely cured. However, a better understanding of the pathways implicated in the evolution and proliferation of cancer cells has led to the development of targeted therapies, that is, agents with action directed at these pathways/features. This approach is more specific to cells within which these pathways, such as epidermal growth factor receptor (EGFR), are overactive; this is in contrast to the relatively indiscriminate mechanism by which cytotoxic chemotherapy tends to affect rapidly dividing cells, regardless of their role. Although factors unique to a given patient, such as the location of the primary tumor (sidedness) or the presence of mutations that confer resistance, may limit the utility of these agents, targeted therapies are now a part of the treatment paradigm for metastatic colorectal cancer, and survival outcomes have significantly improved. This review provides an overview of the role of targeted therapy in the management of patients with colorectal cancer metastases as well as a discussion of issues in patient selection, with a focus on inhibitors of angiogenesis, EGFR-targeted therapy, BRAF mutation-targeted therapies, and other novel strategies, including immunotherapy.

Regorafenib: A Review in Metastatic Colorectal Cancer

Regorafenib (Stivarga^®) is an oral small-molecule multiple kinase inhibitor. It is indicated worldwide for patients with metastatic colorectal cancer (mCRC). In the EU and USA it is indicated for patients with mCRC who have been previously treated with, or are not considered candidates for available therapies, including fluoropyrimidine-based chemotherapy, an anti-VEGF therapy and, if RAS wild-type, an anti-EGFR therapy. In Japan, it is indicated for the treatment of unresectable, advanced/recurrent CRC. The addition of regorafenib to best supportive care prolonged median overall survival (OS; by up to 2.5 months) and progression-free survival (PFS; by up to 1.5 months) relative to the addition of placebo in double-blind phase 3 studies (CORRECT and CONCUR) in patients with mCRC who had progressed after failure of standard therapy. Health-related quality of life was not adversely affected with regorafenib relative to placebo. A large open-label phase 3 study (CONSIGN) and several large real-world studies supported the efficacy of regorafenib in this setting. Regorafenib had a generally manageable tolerability profile, which was consistent with the profile of a typical small-molecule multiple kinase inhibitor. Treatment-related adverse events (AEs), mostly of mild or moderate severity, were reported in the majority of patients receiving regorafenib, with dermatological toxicities and liver enzyme elevations among the most common AEs. Although identification of biomarkers/parameters predicting efficacy outcomes with regorafenib will help to individualize therapy, current evidence indicates that regorafenib is a valuable treatment option for patients with refractory mCRC who have a very poor prognosis.

Regorafenib: A Review in Hepatocellular Carcinoma

Regorafenib (Stivarga^®), a small molecule inhibitor of multiple kinases, is the first drug to be approved for the treatment of hepatocellular carcinoma (HCC) in patients who have progressed during or after sorafenib therapy. Its approval was based on the results of the randomized, double-blind, placebo-controlled, multinational, phase III RESORCE trial in patients with HCC who had progressed during sorafenib therapy. In RESORCE, regorafenib significantly prolonged overall survival (OS; primary endpoint), progression-free survival (PFS) and time to progression (TTP) compared with placebo, with the OS benefit appearing to be largely due to disease stabilization. Regorafenib had an acceptable tolerability profile. The most common treatment-related adverse events in the regorafenib group included hand-foot skin reaction, fatigue, diarrhoea and hypertension. No fatal hepatic failure was reported with regorafenib in patients with HCC in RESORCE. In conclusion, current evidence suggests that regorafenib is an important new targeted therapy option for the treatment of HCC patients who have progressed on sorafenib therapy.

Early modifications of circulating microRNAs levels in metastatic colorectal cancer patients treated with regorafenib

Biomarkers able to improve the cost/benefit ratio are urgently needed for metastatic colorectal cancer patients that are eligible to receive regorafenib. Here, we measured plasma levels of ten circulating microRNAs (c-miRNAs) and we investigated their early changes during treatment, as well as possible correlation with clinical outcome. Ten literature-selected c-miRNAs were quantified by qRT-PCR on plasma samples collected at baseline (d1) and after 15 days of treatment (d15). C-miRNAs showing significant changes were further analyzed to establish correlations with outcome. A decision tree-based approach was employed to define a c-miRNA signature able to predict the outcome. Results achieved in an exploratory cohort were tested in a validation group. In the exploratory cohort (n = 34), the levels of c-miR-21 (p = 0.06), c-miR-141 (p = 0.04), and c-miR-601 (p = 0.01) increased at d15 compared with d1. A c-miRNA signature involving c-miR-21, c-miR-221, and c-miR-760 predicted response to treatment (p < 0.0001) and was significantly associated to PFS (HR = 10.68; 95% CI 3.2-35.65; p < 0.0001). In the validation cohort (n = 36), the increase in c-miR-21 (p = 0.02) and c-miR-601 (p = 0.02) levels at d15 was confirmed, but the associations with outcome were not. Our data indicate that early changes of c-miRNA levels might be influenced by regorafenib treatment. However, further studies are needed to establish the predictive power of such modifications.

Metabolic profiling of the anti-tumor drug regorafenib in mice

Regorafenib is a novel tyrosine kinase inhibitor, which has been approved by the United States Food and Drug Administration for the treatment of various tumors. The purpose of the present study was to describe the metabolic map of regorafenib, and investigate its effect on liver function. Mass spectrometry-based metabolomics approach integrated with multiple mass defect filter was used to determine the metabolites of regorafenib in vitro incubation mixtures (human liver microsomes and mouse liver microsomes), serum, urine and feces samples from mice treated with 80 mg/kg regorafenib. Eleven metabolites including four novel metabolites were identified in the present investigation. As halogen substituted drug, reductive defluorination and oxidative dechlorination metabolites of regorafenib were firstly report in present study. By screening using recombinant cytochrome P450 s (CYPs), CYP3A4 was found to be the principal isoforms involved in regorafenib metabolism. The predication with a molecular docking model confirmed that regorafenib had potential to interact with the active sites of CYP3A4, CYP3A5 and CYP2D6. Serum chemistry analysis revealed no evidence of hepatic damage from regorafenib exposure. This study provided a global view of regorafenib metabolism and its potential side-effects.

The malignant progression effects of regorafenib in human colon cancer cells

A number of anti-angiogenic drugs targeting vascular endothelial growth factor receptors (VEGF-R) have developed and enabled significant advances in cancer therapy including colorectal cancer. However, acquired resistance to the drugs occurs, leading to disease progression, such as invasion and metastasis. How tumors become the resistance and promote their malignancy remains fully uncertain. One of possible mechanisms for the resistance and the progression may be the direct effect of VEGF-R inhibitors on tumor cells expressing VEGF-R. We investigated here the direct effect of a VEGF-R-targeting agent, regorafenib, which is the first small molecule inhibitor of VEGF-Rs for the treatment of patients with colorectal cancer, on phenotype changes in colon cancer HCT116 cells. Treatment of cells with regorafenib for only 2 days activated cell migration and invasion, while vehicle-treated control cells showed less activity. Intriguingly, chronic exposure to regorafenib for 90 days dramatically increased migration and invasion activities and induced a resistance to hypoxia-induced apoptosis. These results suggest that loss of VEGF signaling in cancer cells may induce the acquired resistance to VEGF/VEGF-R targeting therapy by gaining two major malignant phenotypes, apoptosis resistance and activation of migration/invasion.

Overcoming dynamic molecular heterogeneity in metastatic colorectal cancer: Multikinase inhibition with regorafenib and the case of rechallenge with anti-EGFR

In metastatic colorectal cancer (mCRC), fluorouracil-based combination therapy with oxaliplatin or irinotecan is the mainstay of first-line treatment. Patient survival has been significantly improved with the introduction of monoclonal antibodies against VEGF (bevacizumab), VEGFR2 (ramucirumab) or EGFR (cetuximab or panitumumab) in first- and second-line therapies. However, all patients treated with chemotherapy and targeted therapies will eventually relapse, and recently the emergence of alterations in EGFR, RAS, BRAF, ERB-B2, MET and possibly in other genes has been shown to jeopardize response to EGFR blockade. In chemorefractory patients, multikinase inhibition with regorafenib has proved to be effective and rechallenge with chemotherapy or anti-EGFR agents is empirically pursued. This review will critically discuss how the evolving knowledge of mechanisms of resistance driven by intratumoural dynamic molecular heterogeneity can impact on rational choice of treatments in this setting.

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.

Monitoring Cell Death in Regorafenib-Treated Experimental Colon Carcinomas Using Annexin-Based Optical Fluorescence Imaging Validated by Perfusion MRI

Objective

To investigate annexin-based optical fluorescence imaging (OI) for monitoring regorafenib-induced early cell death in experimental colon carcinomas in rats, validated by perfusion MRI and multiparametric immunohistochemistry.

Materials and Methods

Subcutaneous human colon carcinomas (HT-29) in athymic rats (n = 16) were imaged before and after a one-week therapy with regorafenib (n = 8) or placebo (n = 8) using annexin-based OI and perfusion MRI at 3 Tesla. Optical signal-to-noise ratio (SNR) and MRI tumor perfusion parameters (plasma flow PF, mL/100mL/min; plasma volume PV, %) were assessed. On day 7, tumors underwent immunohistochemical analysis for tumor cell apoptosis (TUNEL), proliferation (Ki-67), and microvascular density (CD31).

Results

Apoptosis-targeted OI demonstrated a tumor-specific probe accumulation with a significant increase of tumor SNR under therapy (mean Δ +7.78±2.95, control: -0.80±2.48, p = 0.021). MRI detected a significant reduction of tumor perfusion in the therapy group (mean ΔPF -8.17±2.32 mL/100 mL/min, control -0.11±3.36 mL/100 mL/min, p = 0.036). Immunohistochemistry showed significantly more apoptosis (TUNEL; 11392±1486 vs. 2921±334, p = 0.001), significantly less proliferation (Ki-67; 1754±184 vs. 2883±323, p = 0.012), and significantly lower microvascular density (CD31; 107±10 vs. 182±22, p = 0.006) in the therapy group.

Conclusions

Annexin-based OI allowed for the non-invasive monitoring of regorafenib-induced early cell death in experimental colon carcinomas, validated by perfusion MRI and multiparametric immunohistochemistry.

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.