Pazopanib may be similar to sunitinib in terms of clinical efficacy for treating metastatic renal cell carcinoma (RCC) but it may have a slight advantage when it comes to quality of life.1

Researchers conducted a post-hoc analysis of a randomized, open-label, phase 3 trial of the 2 angiogenesis inhibitors and found that pazopanib may be superior when examining the quality-adjusted time without symptoms or toxicity.1,2

“There are many competing endpoints in oncology trials: survival, tumor growth, adverse events, symptoms, and general health and well-being. For any given treatment comparison, there can be differences that contradict each other,” said study author Jennifer Beaumont, MS, of the Department of Medical Social Sciences at the Northwestern University Feinberg School of Medicine in Chicago, IL. “In this case, pazopanib and sunitinib were similar with respect to progression-free survival and overall survival, while adverse event and quality of life analyses favored pazopanib.”

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Beaumont et al studied overall treatment differences between the 2 agents by using the quality-adjusted time without symptoms or toxicity (Q-TWiST) methodology. Beaumont said the Q-TWiST method produces an overall estimate of treatment difference that incorporates survival, progression, toxicities, and quality of life.

With this methodology, the survival time is partitioned into different health states (time with toxicity, time without symptoms of disease or toxicity of treatment (TWiST), and time after tumor progression or relapse). Beaumont said the time spent in each state is weighted by a health-state utility associated with that state.

“Our analyses suggest a possible overall Q-TWiST benefit to pazopanib over sunitinib, but this effect is small and only statistically significant under particular quality of life weighting combinations. The significant differences occurred when the relative quality of life weight was lower for toxicity because this magnified the observed differences between groups in time spent with toxicities,” Beaumont told Cancer Therapy Advisor.

The analyses examined patients from a previously published study in which 557 patients were treated with pazopanib and 553 patients were treated sunitinib.3

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Beaumont said that several combinations of weights for toxicity or progression significantly favored pazopanib in the post-hoc analyses. In contrast, no combination of weights significantly favored sunitinib. She said patients treated with pazopanib had slightly longer clinical benefits according to Q-TWiST scores in comparison with those treated with sunitinib, primarily because of a reduced toxicity.

“This difference was < 10% of overall survival. Therefore, although there was a statistically significant benefit for pazopanib versus sunitinib in Q-TWiST analyses, the magnitude of that difference tended to be rather small,” said Beaumont.