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

Clinical outcomes of concomitant use of proton pump inhibitors and regorafenib in patients with metastatic colorectal cancer: a multicenter study

AIM

To compare survival outcomes, response rates, and adverse events (AEs) in proton pump inhibitor (PPI) user and non-user patients with metastatic colorectal cancer (mCRC) treated with regorafenib.

METHODS

We included 272 patients with mCRC treated with regorafenib in this study. Patients were divided into two categories according to their status of PPI use. The primary endpoint was overall survival (OS). The secondary endpoints were time to treatment failure (TTF), response rates, and safety. To exclude immortal time bias in survival analyses, we compared PPI non-user patients and all patients.

RESULTS

There were 141 and 131 patients in the PPI non-user and user groups. Baseline characteristics were similar in each group. Pantoprazole was the most used PPI. At the median 35.2 (95% confidence interval (CI): 32.6-37.9) months follow-up, the median OS was similar in PPI non-user and all patients (6.9 months (95% CI: 5.3-8.5) and 7.7 months (95% CI:6.6-8.8), p = 0.913). TTF was also similar in PPI non-user and all patients (3.3 months (95% CI: 2.7-3.9) and 3.5 months (95% CI: 3.0-4.0), p = 0.661). In multivariable analysis, no statistically significant difference was observed between PPI user and non-user groups in OS and TTF (hazard ratio (HR), 0.99; 95% CI, 0.77-1.28; p = 0.963 for OS; HR, 0.93; 0.77-1.20, p = 0.598 for TTF). The objective response rates (ORR) were similar in the PPI non-user and user groups (19.8% and 16.8%, p = 0.455). The rates of any grade AEs were also similar in each group.

CONCLUSION

This study found no worse outcome in the combined use of PPI and regorafenib among patients with mCRC.

Next questions for the medical treatment of gastrointestinal stromal tumor

PURPOSE OF REVIEW

Since its approval in 2002, imatinib remains the standard first-line treatment for patients with advanced gastrointestinal stromal tumors (GISTs). Overall, all the drugs approved for patients who have developed secondary resistance to imatinib are less effective than imatinib in first-line. Even if, overall survival of patients with advanced GIST has improved over time the last 20 years, imatinib-resistant GIST remains therefore a difficult-to-treat cancer. The aim of this review is to elaborate on the potential strategies to improve outcome for patients with imatinib-refractory disease.

RECENT FINDINGS

New-generation potent KIT and PDGFRA inhibitors such as ripretinib and avapritinib developed for the treatment of GIST have shown very promising clinical activity in patients with highly refractory disease. However, both failed to improve outcome in comparison with standard of care in earlier lines settings. Clinical trials investigating the efficacy of multikinase inhibitor with highly specific KIT inhibitors are currently ongoing. Targeting the microenvironment of GIST may also represent a promising approach and is investigated in several clinical studies.

SUMMARY

Imatinib-refractory GIST still represent a therapeutic challenge. It is likely that only combination therapies with new generation of tyrosine kinase inhibitors (TKIs) and/or immune-oncology agents might potentially result in an enhanced therapeutic efficacy compared with current standard of care.

Highly sensitive detection of anti-cancer drug based on bimetallic reduced graphene oxide nanocomposite

Herein, we describe a high-performance electrochemical sensor for the detection of regorafenib (REG) using bimetallic Pd-Ru nanoparticles anchored on pomegranate peel extract (PPE) derived reduced graphene oxide (Pd-Ru/rGO). PPE was employed to neutralize the extremely acidic graphene then cast-off along with the metal precursor for the duration of the chemical reduction to accomplish well dispersed Pd-Ru nanoparticles. Bimetallic Pd-Ru/rGO nanocomposites were synthesized using a facile chemical reduction method. Under optimal conditions, based on the differential pulse voltammetric studies it has been confirmed that the fabricated sensors has good electrocatalytic activity toward the detection of REG, spanning over the linear dynamic range of 0.5-300 nM. Moreover, the sensor exhibited a low limit of detection of 1.6 nM and a limit of quantification of 4.8 nM. The electrochemical sensor unveiled admirable selectivity and sensitivity, reproducibility, and repeatability. The fabricated sensor was suitable for real sample analysis (pharmaceutical tablet, human blood plasm, wastewater) with satisfactory recovery. The strategy presented herein can be employed in the development of electrochemical sensors for other target analytes.

Bioequivalence and Pharmacokinetic Evaluation of Two Oral Formulations of Regorafenib: An Open-Label, Randomised, Single-Dose, Two-Period, Two-Way Crossover Clinical Trial in Healthy Chinese Volunteers Under Fasting and Fed Conditions

Background

Regorafenib is an oral multi-kinase inhibitor approved for the treatment of solid tumours, but the pharmacokinetic profile of regorafenib in the Chinese population is unclear.

Objective

The aim of this study was to examine the pharmacokinetics, bioequivalence, and safety of two formulations of regorafenib 40 mg in healthy Chinese volunteers under fed and fasting conditions.

Methods

A single-centre, randomised, open-label, two-period, two-way crossover phase 1 trial was conducted by randomising a single oral dose of test (T) or reference (R, Stivarga^®) regorafenib (40 mg) to healthy Chinese volunteers under both fasting and fed conditions (high-fat and high-calorie diet). Pharmacokinetic parameters were calculated using non-compartmental methods. Adverse events were recorded to assess drug safety.

Results

Sixty-six participants were enrolled for both fasting and fed treatments. The 90% CIs geometric least-square means of ratio_T/R for regorafenib were completely contained within the equivalence margin of 80–125% under both fasting and fed conditions. Both formulations displayed similar and generally good safety profiles.

Conclusion

Single oral dose of the T (40 mg) and R (40 mg) regorafenib was bioequivalent under fasting and fed conditions and had similar favourable safety profiles among healthy Chinese volunteers.

Extended regorafenib treatment can be linked with mitochondrial damage leading to cardiotoxicity

Regorafenib (RGF) has a great success in the treatment of colorectal cancer, gastrointestinal stromal tumours and hepatocellular carcinoma by inhibiting angiogenic, stromal and oncogenic kinases. However, RGF can induce life-threatening cardiotoxicity including hypertension and cardiac ischemia/infarction. The molecular mechanism of the adverse effects has not been elucidated. Mitochondrial dysfunction is one of the major causes of cardiac diseases since cardiac cells highly need ATP for their contractility. Therefore, we aimed to investigate molecular mechanisms of RGF-induced cardiac adverse effects using H9c2 cell model by focusing on mitochondria. Cells were treated with 0-20 μM RGF for 48 and 72 h. According to our results, RGF inhibited cell proliferation and decreased the ATP content of the cells depending on the exposure time and concentration. Loss of mitochondrial membrane potential was also observed at high dose. Mitochondrial fusion/fission genes and antioxidant SOD2 (superoxide dismutase) gene expression levels increased at high doses in both treatments. Mitochondrial DNA content decreased as exposure time and concentration increased. Also, protein expression levels of mitochondrial complex I and V have reduced and stress protein HSP70 level has increased following RGF treatment. Structural abnormalities in mitochondria was seen with transmission electron microscopy at the applied higher doses. Our findings suggest that RGF-induced cardiotoxicity may be associated with mitochondrial damage in cardiac cells.

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.

Drug Sensitivity Screening and Targeted Pathway Analysis Reveal a Multi-Driver Proliferative Mechanism and Suggest a Strategy of Combination Targeted Therapy for Colorectal Cancer Cells

Treatment of colorectal cancer mostly relies on traditional therapeutic approaches, such as surgery and chemotherapy. Limited options of targeted therapy for colorectal cancer narrowly focus on blocking cancer-generic targets VEGFR and EGFR. Identifying the oncogenic drivers, understanding their contribution to proliferation, and finding inhibitors to block such drivers are the keys to developing targeted therapy for colorectal cancer. In this study, ten colorectal cancer cell lines were screened against a panel of protein kinase inhibitors blocking key oncogenic signaling pathways. The results show that four of the 10 cell lines did not respond to any kinase inhibitors significantly, the other six were mildly inhibited by AZD-6244, BMS-754807, and/or dasatinib. Mechanistic analyses demonstrate that these inhibitors independently block the MAP kinase pathway, IR/IGF-1R/AKT pathway, and Src kinases, suggesting a multi-driver nature of proliferative signaling in these cells. Most of these cell lines were potently and synergistically inhibited by pair-wise combinations of these drugs. Furthermore, seven of the 10 cell lines were inhibited by the triple combination of AZD-6244/BMS-754807/dasatinib with IC₅₀’s between 10 and 84 nM. These results suggest that combination targeted therapy may be an effective strategy against colorectal cancer.

Medication-related osteonecrosis of the jaw unrelated to bisphosphonates and denosumab-a review

The link between medication-related osteonecrosis of the jaw (MRONJ) and bone modulating drugs, such as bisphosphonates and denosumab, is well established, and the number of reported cases is increasing. The development of novel medications used in the treatment of cancer, as well as autoimmune and bone conditions, has led to more cases of MRONJ being reported. However, in addition to this group of medications, increasing numbers of new agents in cancer therapy, such as antiangiogenic agents, have also been implicated in the development of MRONJ. As these newer agents with similar mechanisms are routinely used, the numbers of reported cases will likely rise further. This article aims to identify and summarize the drugs implicated in MRONJ, besides bisphosphonates and denosumab. A wide range of medications classified as tyrosine kinase inhibitors, monoclonal antibodies, mammalian target of rapamycin inhibitors, radiopharmaceuticals, selective estrogen receptor modulators, and immunosuppressants have been implicated in MRONJ. It remains crucial that oral health care providers are aware of these new medications and their associated risks to manage their patients appropriately.

Regorafenib suppresses colon tumorigenesis and the generation of drug resistant cancer stem-like cells via modulation of miR-34a associated signaling

Background

Colorectal cancer (CRC) is one of the most prevalent malignancies in the world and developed drug resistance has represented one of the most challenging tasks for management. The current therapeutic regimens may select and enrich cancer stem-like cells (CSCs) resulting in the increased resistance against treatment, metastatic potential and mortality. Regorafenib is a multi-kinase inhibitor, an FDA-approved last-of-line treatment for patients with chemo-refractory metastatic CRC. However, regorafenib’s potential effects on CSCs have not been fully elucidated.

Methods

Here, we developed two 5-FU resistant CRC cell lines, HCT-116R and DLD-1R and showed the increased CSCs characteristics such as increased side-population cells, tumor sphere formation and expression of stemness markers. These cell lines and CSCs properties were used for evaluating the potential of regorafenib in suppressing CSCs.

Results

We showed that regorafenib treatment decreased the stemness phenotypes including tumor sphere formation, and side-population, of both HCT-116R and DLD-1R cells. Additionally, regorafenib suppressed the cell viability in both cell lines synergistically with 5-FU. In vivo, the combination of regorafenib and 5-FU significantly suppressed the tumorigenesis and stemness markers of 5-FU resistant DLD-1R. Mechanistically, regorafenib-mediated effects were associated with the induction of tumor suppressor miR-34a and suppression of WNT/β-catenin signaling. Our findings demonstrated that regorafenib treatment was associated with the increased level of miR-34a, resulting in reversing drug resistance and cancer-initiating cell phenotypes by degrading WNT/β-catenin in CRC.

Conclusion

Regorafenib might be a potential drug for colon cancer stem-like cells and it should be investigated in future clinical trials.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0836-x) contains supplementary material, which is available to authorized users.

The anti-tumor effect of regorafenib in lung squamous cell carcinoma in vitro

Lung squamous cell carcinoma (LSCC) is a common type of non-small-cell lung cancer (NSCLC) and lacks effective treatment. Regorafenib, an oral multikinase inhibitor, has demonstrated promising anti-tumor activity in various solid tumors. To study whether regorafenib inhibits LSCC cells, we investigate the compound in several LSCC cell lines and explore the possible mechanism. In this study, we confirmed that regorafenib had anti-proliferation effect on LSCC cell lines by inducing G0/G1 arrest. In addition, glycogen synthase kinase 3β (GSK3β) remained at the same level and Ser9 phosphorylation of GSK3β decreased with increasing incubation time and increasing regorafenib concentration in LSCC cells. GSK3β inhibition enhanced the anti-tumor activity of regorafenib. Thus, GSK3β activation restricted the anti-cancer effect of regorafenib on LSCC. In conclusion, regorafenib might be a promising drug for LSCC therapy. GSK3β might be a potential target to increase the anti-tumor effect of regorafenib in LSCC cells.

Topical administration of regorafenib eye drops: phase I dose-escalation study in healthy volunteers

Aim

Regorafenib is a multikinase inhibitor under investigation for use in neovascular age‐related macular degeneration. In this phase I study, regorafenib eye drops were administered to healthy volunteers to provide information on safety, tolerability and systemic exposure.

Methods

This was a single‐centre, randomized, double‐masked, parallel‐group, dose‐escalation, placebo‐controlled study. Subjects received regorafenib eye drops (30 mg ml⁻¹, 25 μl) as a 0.75 mg single dose (Cohort 1), 0.75 mg twice daily (bid) or thrice daily (tid) over 14 days (Cohorts 2 and 3, respectively), 1.5 mg tid unilaterally for 3 days, then bilaterally for up to 14 days (Cohort 4), or placebo. Plasma samples were taken to estimate systemic exposure. Safety and functional assessments were performed throughout the study.

Results

Thirty‐six subjects received regorafenib and 12 received placebo. Regorafenib was safe and well tolerated over the dose range. No pathological changes occurred in the anterior, vitreous or posterior eye compartments. Mild eyelid redness, oedema and conjunctival hyperaemia were observed across all regorafenib cohorts; these were comparable with the effects seen with placebo. Predominant symptoms were blurred vision in the active and placebo groups. Systemic safety evaluations showed no clinically relevant findings. Absolute systemic exposure after multiple administrations of regorafenib eye drops at a dose of 0.75 mg was 600–700‐fold lower than after multiple oral administration of 160 mg day⁻¹, the dose approved in cancer indications.

Conclusion

These results indicate a favourable safety and tolerability profile of regorafenib eye drops up to 30 mg ml⁻¹ tid for use in clinical studies.

ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biological therapies: an infectious diseases perspective (Cell surface receptors and associated signaling pathways)

BACKGROUND

The present review is part of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Infections in Compromised Hosts (ESGICH) consensus document on the safety of targeted and biologic therapies.

AIMS

To review, from an infectious diseases perspective, the safety profile of therapies targeting cell surface receptors and associated signaling pathways among cancer patients and to suggest preventive recommendations.

SOURCES

Computer-based Medline searches with MeSH terms pertaining to each agent or therapeutic family.

CONTENT

Vascular endothelial growth factor (VEGF)-targeted agents (bevacizumab and aflibercept) are associated with a meaningful increase in the risk of infection, likely due to drug-induced neutropaenia, although no clear benefit is expected from the universal use of anti-infective prophylaxis. VEGF tyrosine kinase inhibitors (i.e. sorafenib or sunitinib) do not seem to significantly affect host's susceptibility to infection, and universal anti-infective prophylaxis is not recommended either. Anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (cetuximab or panitumumab) induce neutropaenia and secondary skin and soft tissue infection in cases of severe papulopustular rash. Systemic antibiotics (doxycycline or minocycline) should be administered to prevent the latter complication, whereas no recommendation can be established on the benefit from antiviral, antifungal or anti-Pneumocystis prophylaxis. A lower risk of infection is reported for anti-ErbB2/HER2 monoclonal antibodies (trastuzumab and pertuzumab) and ErbB receptor tyrosine kinase inhibitors (including dual-EGFR/ErbB2 inhibitors such as lapatinib or neratinib) compared to conventional chemotherapy, presumably as a result of the decreased occurrence of drug-induced neutropaenia.

IMPLICATIONS

With the exception of VEGF-targeted agents, the overall risk of infection associated with the reviewed therapies seems to be low.

Mechanisms of toxicity associated with six tyrosine kinase inhibitors in human hepatocyte cell lines

Tyrosine kinase inhibitors have revolutionized the treatment of certain cancers. They are usually well tolerated, but can cause adverse reactions including liver injury. Currently, mechanisms of hepatotoxicity associated with tyrosine kinase inhibitors are only partially clarified. We therefore aimed at investigating the toxicity of regorafenib, sorafenib, ponatinib, crizotinib, dasatinib and pazopanib on HepG2 and partially on HepaRG cells. Regorafenib and sorafenib strongly inhibited oxidative metabolism (measured by the Seahorse-XF24 analyzer) and glycolysis, decreased the mitochondrial membrane potential and induced apoptosis and/or necrosis of HepG2 cells at concentrations similar to steady-state plasma concentrations in humans. In HepaRG cells, pretreatment with rifampicin decreased membrane toxicity (measured as adenylate kinase release) and dissipation of adenosine triphosphate stores, indicating that toxicity was associated mainly with the parent drugs. Ponatinib strongly impaired oxidative metabolism but only weakly glycolysis, and induced apoptosis of HepG2 cells at concentrations higher than steady-state plasma concentrations in humans. Crizotinib and dasatinib did not significantly affect mitochondrial functions and inhibited glycolysis only weakly, but induced apoptosis of HepG2 cells. Pazopanib was associated with a weak increase in mitochondrial reactive oxygen species accumulation and inhibition of glycolysis without being cytotoxic. In conclusion, regorafenib and sorafenib are strong mitochondrial toxicants and inhibitors of glycolysis at clinically relevant concentrations. Ponatinib affects mitochondria and glycolysis at higher concentrations than reached in plasma (but possibly in liver), whereas crizotinib, dasatinib and pazopanib showed no relevant toxicity. Mitochondrial toxicity and inhibition of glycolysis most likely explain hepatotoxicity associated with regorafenib, sorafenib and possibly pazopanib, but not for the other compounds investigated.

Regorafenib inhibited gastric cancer cells growth and invasion via CXCR4 activated Wnt pathway

AIM

Regorafenib is an oral small-molecule multi kinase inhibitor. Recently, several clinical trials have revealed that regorafenib has an anti-tumor activity in gastric cancer. However, only part of patients benefit from regorafenib, and the mechanisms of regorafenib's anti-tumor effect need further demonstrating. In this study, we would assess the potential anti-tumor effects and the underlying mechanisms of regorafenib in gastric cancer cells, and explore novel biomarkers for patients selecting of regorafenib.

METHODS

The anti-tumor effects of regorafenib on gastric cancer cells were analyzed via cell proliferation and invasion. The underlying mechanisms were demonstrated using molecular biology techniques.

RESULTS

We found that regorafenib inhibited cell proliferation and invasion at the concentration of 20μmol/L and in a dose dependent manner. The anti-tumor effects of regorafenib related to the decreased expression of CXCR4, and elevated expression and activation of CXCR4 could reverse the inhibition effect of regorafenib on gastric cancer cells. Further studies revealed that regorafenib reduced the transcriptional activity of Wnt/β-Catenin pathway and led to decreased expression of Wnt pathway target genes, while overexpression and activation of CXCR4 could attenuate the inhibition effect of regorafenib on Wnt/β-Catenin pathway.

CONCLUSIONS

Our findings demonstrated that regorafenib effectively inhibited cell proliferation and invasion of gastric cancer cells via decreasing the expression of CXCR4 and further reducing the transcriptional activity of Wnt/β-Catenin pathway.

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.