Sunitinib: the first to arrive at first-line metastatic renal cell carcinoma

Negative Effect of Immediate Sunitinib Interruption on Survival in Patients With Metastatic Renal Cell Carcinoma

BACKGROUND

Treatment modification due to adverse events reduces the dose intensity in cancer treatment. The prognostic impact of sunitinib treatment interruption within the initial period of therapy for metastatic renal cell carcinoma (mRCC) remains unknown.

PATIENTS AND METHODS

We retrospectively evaluated 97 patients with mRCC treated with first-line sunitinib treatment. The patients were classified into two groups according to the presence of treatment interruption (TI) within the initial two cycles. The prognostic impact of TI was analyzed using the Kaplan-Meier method and log-rank test, and multivariate analyses using the Cox proportional hazard model.

RESULTS

Thirty-eight patients (39.2%) experienced an immediate TI. The median progression-free (PFS) and overall (OS) survival were significantly shorter in patients with a TI than in those without (PFS= 6.54 vs. 11.3 months, p=0.0246; OS=16.9 vs. 30.0 months, p=0.0420). Multivariate analyses for PFS and OS showed that TI was an independent factor predicting poorer PFS (hazard ratio(HR)=1.93, p=0.0141) and OS (HR=2.09, p=0.0102). In addition, the relative dose intensity within the initial two cycles was significantly lower in patients with a TI than in those without (52.7% vs. 75.0%, p<0.0001).

CONCLUSION

This study showed the significantly negative effect of immediate TI on survival of patients under sunitinib treatment for mRCC. Therefore, the careful monitoring of patient tolerability is required in order to maintain therapeutic efficacy in the early phase of sunitinib treatment.

Does sunitinib have a patient-specific dose without diminishing its antitumor effect on advanced pancreatic neuroendocrine neoplasms?

PURPOSE

Because it is unknown whether adjusting the dose of sunitinib can benefit patients with pancreatic neuroendocrine neoplasms (Pan-NENs), this retrospective study examined maximum tumor shrinkage rates and prognoses in patients with and without low doses of sunitinib administration.

METHODS

Eighty-seven patients with metastatic and unresectable neoplasms, treated with sunitinib for > 1 month, were divided into a low-dose (LD) or high-dose (HD) group. The tumor response rates were investigated over time using computed tomography according to the response evaluation criteria in solid tumors criteria.

RESULTS

The LD and HD groups included 42 and 45 patients, respectively. There were no differences in baseline characteristics (tumor size, Ki-67 index, mitosis, and differentiation) between the two groups. Progressive disease (PD), stable disease (SD), and partial response (PR) were observed in 16.7, 54.8, and 28.6% of patients in the LD group, respectively, and in 13.3, 60, and 26.7% of patients in the HD group, respectively. There were no differences in tumor shrinkage rates between the two groups (p = 0.87). The 3-year progression-free survival rates for the LD and HD groups were 2.4% and 2.3%, respectively (p = 0.67), and the 3-year overall survival rates were 57.9% and 70.5%, respectively (p = 0.76). The occurrence of adverse events was similar between the two groups (61.9% vs. 60.0%, p > 0.95).

CONCLUSIONS

Dose reduction of sunitinib did not alter tumor shrinkage rates or prognoses for patients with advanced Pan-NENs.

Overcoming intratumoural heterogeneity for reproducible molecular risk stratification: a case study in advanced kidney cancer

BACKGROUND

Metastatic clear cell renal cell cancer (mccRCC) portends a poor prognosis and urgently requires better clinical tools for prognostication as well as for prediction of response to treatment. Considerable investment in molecular risk stratification has sought to overcome the performance ceiling encountered by methods restricted to traditional clinical parameters. However, replication of results has proven challenging, and intratumoural heterogeneity (ITH) may confound attempts at tissue-based stratification.

METHODS

We investigated the influence of confounding ITH on the performance of a novel molecular prognostic model, enabled by pathologist-guided multiregion sampling (n = 183) of geographically separated mccRCC cohorts from the SuMR trial (development, n = 22) and the SCOTRRCC study (validation, n = 22). Tumour protein levels quantified by reverse phase protein array (RPPA) were investigated alongside clinical variables. Regularised wrapper selection identified features for Cox multivariate analysis with overall survival as the primary endpoint.

RESULTS

The optimal subset of variables in the final stratification model consisted of N-cadherin, EPCAM, Age, mTOR (NEAT). Risk groups from NEAT had a markedly different prognosis in the validation cohort (log-rank p = 7.62 × 10^-7; hazard ratio (HR) 37.9, 95% confidence interval 4.1-353.8) and 2-year survival rates (accuracy = 82%, Matthews correlation coefficient = 0.62). Comparisons with established clinico-pathological scores suggest favourable performance for NEAT (Net reclassification improvement 7.1% vs International Metastatic Database Consortium score, 25.4% vs Memorial Sloan Kettering Cancer Center score). Limitations include the relatively small cohorts and associated wide confidence intervals on predictive performance. Our multiregion sampling approach enabled investigation of NEAT validation when limiting the number of samples analysed per tumour, which significantly degraded performance. Indeed, sample selection could change risk group assignment for 64% of patients, and prognostication with one sample per patient performed only slightly better than random expectation (median logHR = 0.109). Low grade tissue was associated with 3.5-fold greater variation in predicted risk than high grade (p = 0.044).

CONCLUSIONS

This case study in mccRCC quantitatively demonstrates the critical importance of tumour sampling for the success of molecular biomarker studies research where ITH is a factor. The NEAT model shows promise for mccRCC prognostication and warrants follow-up in larger cohorts. Our work evidences actionable parameters to guide sample collection (tumour coverage, size, grade) to inform the development of reproducible molecular risk stratification methods.

Effective chemotherapy of heterogeneous and drug-resistant early colon cancers by intermittent dose schedules: a computer simulation study

PURPOSE

The effectiveness of cancer chemotherapy is limited by intra-tumor heterogeneity, the emergence of spontaneous and induced drug-resistant mutant subclones, and the maximum dose to which normal tissues can be exposed without adverse side effects. The goal of this project was to determine if intermittent schedules of the maximum dose that allows colon crypt maintenance could overcome these limitations, specifically by eliminating mixtures of drug-resistant mutants from heterogeneous early colon adenomas while maintaining colon crypt function.

METHODS

A computer model of cell dynamics in human colon crypts was calibrated with measurements of human biopsy specimens. The model allowed simulation of continuous and intermittent dose schedules of a cytotoxic chemotherapeutic drug, as well as the drug's effect on the elimination of mutant cells and the maintenance of crypt function.

RESULTS

Colon crypts can tolerate a tenfold greater intermittent dose than constant dose. This allows elimination of a mixture of relatively drug-sensitive and drug-resistant mutant subclones from heterogeneous colon crypts. Mutants can be eliminated whether they arise spontaneously or are induced by the cytotoxic drug.

CONCLUSIONS

An intermittent dose, at the maximum that allows colon crypt maintenance, can be effective in eliminating a heterogeneous mixture of mutant subclones before they fill the crypt and form an adenoma.

Treatment of sunitinib-induced hypertension in solid tumor by nitric oxide donors

Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) are overexpressed in the majority of renal cell carcinomas. This characteristic has supported the rationale of targeting VEGF-driven tumour vascularization, especially in clear cell RCC. VEGF-inhibiting strategies include the use of tyrosine kinase inhibitors (sunitinib, axitinib, pazopanib, and sorafenib) and neutralizing antibodies such as bevacizumab.

Hypertension (HTN) is one of the most common adverse effects of angiogenesis inhibitors. HTN observed in clinical trials appears to correlate with the potency of VEGF kinase inhibitor against VEGFR-2: agents with higher potency are associated with a higher incidence of HTN. Although the exact mechanism by tyrosine kinase inhibitors induce HTN has not yet been completely clarified, two key hypotheses have been postulated. First, some studies have pointed to a VEGF inhibitors-induced decrease in nitric oxide synthase (NOS) and nitric oxide (NO) production, that can result in vasoconstriction and increased blood pressure. VEGF, mediated by PI3K/Akt and MAPK pathway, upregulates the endothelial nitric oxide synthase enzyme leading to up-regulation of NO production. So inhibition of signaling through the VEGF pathway would lead to a decrease in NO production, resulting in an increase in vascular resistance and blood pressure. Secondly a decrease in the number of microvascular endothelial cells and subsequent depletion of normal microvessel density (rarefaction) occurs upon VEGF signaling inhibition.

NO donors could be successfully used not only for the treatment of developed angiogenesis-inhibitor-induced hypertension but also for preventive effects.

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Hypertension appears to correlate with the potency of VEGF kinase inhibitor against VEGFR-2.

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Sunitinib is associated with several side effects, with hypertension being the most common one.

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VEGF inhibitors induce decrease in nitric oxide synthase and nitric oxide production, that can result in vasoconstriction and increased blood pressure.

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NO donors could be successfully used for the treatment of angiogenesis-inhibitor-induced hypertension and also for preventive effects.

Hampering immune suppressors: therapeutic targeting of myeloid-derived suppressor cells in cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells with suppressive properties that preferentially expand in cancer. Myeloid-derived suppressor cells mainly suppress T-cell proliferation and cytotoxicity, inhibit natural killer cell activation, and induce the differentiation and expansion of regulatory T cells. The wide spectrum of MDSC suppressive activity in cancer and its role in tumor progression have rendered these cells a promising target for effective cancer immunotherapy. In this review we briefly discuss the origin of MDSCs and their main mechanisms of suppression and focus more on the approaches developed up to date targeting of MDSCs in tumor-bearing animals and cancer patients.

Ageing-related responses to antiangiogenic effects of sunitinib in atherosclerosis-prone mice

Antiangiogenic therapies in cancer exert their effects in the context of age-related comorbidities, which affect the entirety of the vascular system. Among those conditions, the impact of atherosclerosis is especially prevalent, but poorly understood, and not reflected in mouse models routinely used for testing antiangiogenic therapeutics. Our earlier work suggested that these obstacles can be overcome with the use of atherosclerosis-prone ApoE-/- mice harbouring syngeneic transplantable Lewis Lung Carcinoma (LLC). Here we report that, sunitinib, the clinically approved, antiangiogenic inhibitor impedes global tumor growth to a greater extent in aged then in young mice. This activity was coupled with changes in the tumor microenvironment, which in aged mice was characterized by pronounced hypoxia, reduction in microvascular density (MVD) and lower pericyte coverage, relative to young controls. We also detected soluble VEGR2 in plasma of sunitinib treated mice. Interestingly, sunitinib modulated tumor infiltration with bone marrow-derived cells (CD45+), recruitment of M2-like macrophages (CD163+) and activation of inflammatory pathways (phospho-STAT3) in a manner that was age-dependent. We suggest that age and atherosclerosis may alter the effects of sunitinib on the tumor microenvironment, and that these considerations may also apply more broadly to other forms of antiangiogenic treatment in cancer.

The effect of sunitinib on the plasma exposure of intravenous paracetamol and its major metabolite: paracetamol glucuronide

The study aimed to examine the effect of sunitinib on the plasma exposure of intravenous paracetamol and its major metabolite, paracetamol glucuronide. Both drugs share metabolic pathways in the liver, and the drug interactions between sunitinib and paracetamol administered in higher doses were reported. These interactions resulted in hepatotoxicity. The adult New Zealand male rabbits were divided into three groups (6 animals each): rabbits receiving sunitinib and paracetamol (SUN + PC), rabbits receiving sunitinib (SUN), and a control group receiving paracetamol (PC). Sunitinib was administered orally (25 mg) and paracetamol was administrated intravenously (35 mg/kg). Blood samples for sunitinib and SU12662 assays were collected up to 96 h after drug administration and for paracetamol and paracetamol glucuronide up to 300 min after drug administration. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin were analysed before and after drug administration. A number of pharmacokinetic parameters were analysed. There were no differences in the levels of AST, ALT, and bilirubin among the groups at either time point. Significantly higher values of AUC_0–t, AUC_0–∞, and C_max and lower clearance and volume of distribution of paracetamol were observed in group PC vs. group SUN + PC (p < 0.01). The maximum plasma concentration of paracetamol glucuronide tended to be higher in group PC 213.27 μg/mL (90 % CI 1.06, 1.25; p = 0.0267). Statistically significant differences were revealed for paracetamol glucuronide mean residence time (MRT); MRT was higher in group SUN + PC than in group PC (p = 0.0375). The mean t_max of paracetamol glucuronide was similar in both groups: SUN + PC and group PC (15 and 20 min, respectively). The mean t_max of sunitinib was different in groups SUN + PC and SUN (10.0 and 7.0, respectively; p = 0.0134). At the studied doses, neither of the drugs, whether administered alone or together, had hepatotoxic effects. The present study was not able to confirm that sunitinib, administered at low doses in conjunction with paracetamol, displays a hepatoprotective effect. Significant differences were observed in some pharmacokinetic parameters of paracetamol.

Anti-angiogenic drug discovery: lessons from the past and thoughts for the future

INTRODUCTION

Since the pioneering work of Judah Folkman, the discovery of bevacizumab has introduced the use of anti-angiogenic agents as a new modality for the treatment of cancer. Currently, hundreds of clinical trials involving anti-angiogenic agents, targeting different elements of the tumour angiogenesis pathway, are underway. However, thus far, the benefits of anti-angiogenic therapy in unselected patient populations are often marginal with harmful side effects.

AREAS COVERED

This article presents a detailed discussion of the lessons learnt from the use of bevacizumab and other VEGF pathway inhibitors in the clinical setting. Specifically, this article provides a review of the literature on anti-VEGF agents and other angiogenesis inhibitors used in pre-clinical and clinical trials for cancer treatment.

EXPERT OPINION

Future anti-angiogenic drug design centres on multiple protein targets and combinations including: growth factors, hypoxia-inducible factor and tumour endothelial cell markers unique to the tumour vasculature. Furthermore, treatment dosing, scheduling and combination with radiation and chemotherapy require further investigation, as does the potential of treating early disease, and the development of biomarkers which accurately predict response to therapy. These are essential for the future development of these drugs with individualised therapy likely to be the ultimate goal.