medwireNews: Patients with bone metastases respond better to cabozantinib than everolimus, demonstrates a subgroup analysis of renal cell carcinoma (RCC) patients from the METEOR trial.
Initial findings for the multi-kinase inhibitor in the phase III trial led to cabozantinib being the standard of care for advanced RCC, explain Bernard Escudier, from Institut Gustave Roussy in Villejuif, France, and co-workers.
To investigate the impact of cabozantinib on patients with bone metastases in the study, the team collated data for 77 patients who were randomly assigned to receive cabozantinib 60 mg/day and 65 patients who were given the mTOR inhibitor everolimus 10 mg/day.
Median progression-free survival (PFS) was 7.4 months with cabozantinib versus 2.7 months for everolimus, giving a hazard ratio (HR) of 0.33. The corresponding values for overall survival (OS) were 20.1 and 12.1 months and a HR of 0.54.
“Although our study was not powered for statistical testing of the subgroup analyses, the values of the HRs and medians for PFS and OS for patients with bone metastases were notable and favored cabozantinib over everolimus”, the team writes in the Journal of Clinical Oncology.
Furthermore, the objective response rate (ORR) was 17% for the 77 patients with bone metastases alone and 20% for the 60 patients with both bone and visceral metastases, whereas none of the everolimus-treated patients with bone metastases showed an objective response.
In addition, an independent radiology committee-assessed bone scan response was noted in 20% of the cabozantinib group and 10% of the everolimus group. Patients given cabozantinib also had greater changes in bone biomarkers than their everolimus-treated counterparts, namely decreases in the bone formation marker P1NP and the resorption marker CTx.
Cabozantinib and everolimus showed “similar” safety profiles, the researchers say, although grade 3 and 4 adverse events were more common with cabozantinib than everolimus, at 73% versus 51%. This might be explained by patients using cabozantinib remaining on treatment for a median of 9.8 months compared with just 3.7 months for those taking everolimus, they suggest.
The rate of skeletal-related events – defined as pathologic fracture, spinal cord compression, or the need for surgery or radiotherapy – was 23% and 29%, respectively, occurring after a median of 3.7 and 2.5 months.
“Our results are also consistent with those from the phase II CABOSUN trial in first-line patients with advanced RCC, in which a PFS benefit with cabozantinib was maintained in patients with bone metastases compared with sunitinib”, Bernard Escudier et al comment.
Recognising the need for new therapies for this patient population with a poor prognosis, the researchers conclude: “Cabozantinib is a standard of care for previously treated patients with advanced RCC, with clinical benefits in PFS, OS, and ORR that are observed irrespective of the presence of bone metastases.
“On the basis of these outcomes, cabozantinib represents a good treatment option for this difficult-to-treat patient population.”
Escudier B, Powles T, Motzer RJ, et al. Cabozantinib, a new standard of care for patients with advanced renal cell carcinoma and bone metastases? Subgroup analysis of the METEOR trial. J Clin Oncol; Advance online publication 8 January 2018. DOI: 10.1200/JCO.2017.74.7352
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