Axitinib, Sorafenib Offer Similar Survival in mRCC Patients
VIENNA—Axitinib therapy is associated with an overall survival (OS) similar to that of sorafenib therapy as second-line treatment of metastatic renal cell carcinoma (mRCC), according to updated findings presented at the European Society for Medical Oncology 2012 Congress.
Study investigator Brian Rini, MD, reported updated findings from the phase 3 AXIS trial, which showed that axitinib prolonged progression-free survival compared with sorafenib as second-line therapy for mRCC (median 6.7 vs. 4.7 months). He presented data on 723 patients with clear cell mRCC who experienced progressive disease after an initial course of systemic therapy. Patients with an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1 were stratified by ECOG PS and prior therapy and then enrolled in the study. All patients were randomized to receive axitinib 5 mg twice daily or sorafenib 400 mg twice daily.
Dr. Rini and his colleagues analyzed OS as a secondary endpoint based on 425 events. The investigators grouped subjects according to diastolic blood pressure (DBP) on therapy (one or more DBP measurements of 90 mm Hg or higher compared with DBP less than 90 mm Hg).
The median OS was 20.1 months for the axitinib arm and 19.2 months for the sorafenib arm. “We were not surprised. The overall survival was not significantly better, but numerically different,” said Dr. Rini, Professor of Medicine at Cleveland Clinic's Lerner College of Medicine of Case Western Reserve University.
Effect of prior therapy
The investigators studied prior therapy subsets and found that the median OS with axitinib compared to sorafenib with prior cytokine use favored axitinib over sorafenib (29.4 vs. 27.8 months). Among patients previously treated with sunitinib, however, sorafenib was associated with better OS than axitinib (15.2 vs. 16.5 months).
Prognostic factors associated with longer OS with second-line therapy included type of prior therapy and ECOG PS = 0, Dr. Rini and colleagues found. Other factors associated with longer OS were elevated hemoglobin levels, the absence of bone metastases, and low corrected calcium levels.
OS in both arms of the study was significantly longer in patients with a DBP of 90 mm Hg or greater compared with a lower DBP (20.7 vs. 12.9 months in the axitinib arm and 20.2 vs. 14.8 months in the sorafenib arm) at the 12-week evaluation.
“They [the drugs] both have different targets and we need to get a handle on which one may work better in different patient subgroups,” Dr. Rini said. “We don't have any biomarkers to predict yet which patients will do better with each agent.”