Long-term axitinib in RCC effective with ‘controllable’ toxicities

By Shreeya Nanda, Senior medwireNews Reporter

Axitinib treatment is effective in the long-term in Japanese patients with metastatic renal cell carcinoma (RCC) and has manageable toxicity, a phase II study suggests.

In this multicentre, open-label trial, 64 Japanese patients were treated with the vascular endothelial growth factor receptor (VEGFR) inhibitor axitinib at a starting dose of 5 mg twice daily for a median duration of 14.2 months.

The objective response rate, as assessed by an independent review committee (IRC), was 51.6%, with 33 participants achieving a partial response and 28 having stable disease for at least 8 weeks. The median duration of response was 11.1 months, and median progression-free survival, as per the IRC assessment, was 11.0 months.

Masatoshi Eto (Kumamoto University) and co-workers report that median overall survival (OS) at the data cutoff point was 37.3 months. Patients categorised in the favourable-, intermediate- and poor-risk groups in accordance with the Memorial Sloan-Kettering Cancer Center criteria had a median OS of 33.8, 41.3 and 17.4 months, respectively.

Noting that intermediate-risk patients had a better prognosis than those in the favourable-risk group, the researchers point out that such associations are assessed on the basis of baseline status and that "any changes in the status or factors during the study are not being taken into account and a possible impact of any such changes would likely be magnified with a smaller number of patients analyzed."

Exploratory analysis showed a significant correlation between OS and changes in the levels of soluble VEGFR-2 from baseline. Median OS was 47.0 months in patients who had a greater percent decrease than the median of 33.5% and 34.6 months in those whose soluble VEGFR-2 levels decreased by less than the median.

“Changes in the plasma levels of [soluble] VEGFR-2 may be used as a prognostic factor for OS in [metastatic RCC] following axitinib treatment”, say Eto et al.

The grade 3 or 4 treatment-related adverse events that occurred most frequently included hypertension (73%), hand–foot syndrome (22%), fatigue (6%) and diarrhoea (5%). Proteinuria at grade 3 or 4, which occurred in 9% of patients, was the only adverse event to result in treatment discontinuation.

Forty-four percent of patients were taking antihypertensive medication at study entry; this increased to 94% following axitinib treatment. Additionally, 31 participants developed hypothyroidism during the course of the study.

The authors therefore conclude in Cancer Science that the toxicities with long-term treatment with axitinib were generally controllable but recommend close monitoring and management.

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