Long-term responders to targeted therapy for metastatic renal cell carcinoma (mRCC) have excellent outcomes, with patients who have a complete response to treatment experiencing the longest survival, researchers reported.
In a retrospective registry-based study, Tomas Buchler, MD, PhD, of Charles University and Thomayer University Hospital in Prague, Czech Republic, and colleagues analyzed the outcomes of 219 mRCC patients who received continuous first-line targeted therapy with inhibitors of vascular endothelial growth factor (VEGF), namely sunitinib, sorafenib, pazopanib, or bevacizumab, for at least 2 years. The vast majority of the cohort (166 patients, 75.8%) received sunitinib.
Median progression-free survival (PFS) after initiation of treatment was 39.7 months, with 5-year PFS of 34.2%, Dr Buchler’s team reported online in Clinical Genitourinary Cancer. Median overall survival (OS) reached 79.1 months, with 5-year OS of 62.1%. Of the 219 patients, 28 achieved complete response (CR) and 103 and 88 achieved partial response (PR) or had stable disease (SD), respectively.
Among the CR patients, the median PFS and OS had not been reached. The median PFS and OS in the PR group was 36.4 months and 64.9 months, respectively. In the SD group, the median PFS and OS were 39.2 months and 67.9 months, respectively.
“The present analysis of a large cohort of long-term responders to anti-VEGF therapy has shown marked differences in PFS and OS between patients achieving CR and non-CR as the best clinical response at the landmark of 2 years,” the authors concluded. “Patients with non-CR experienced a relatively high progression rate shortly after the landmark time point.”
The median follow-up duration for CR, PR, or SD patients who were still alive was 62, 52, and 51 months, respectively, Dr Buchler and his collaborators noted. As of the data cutoff date, median treatment duration in these groups was 40, 32, and 35 months.
Of the 68 deaths that occurred during the study period, 89.5% were cancer-related.
Beyond 2 years, targeted treatment was discontinued in 21 (75%), 80 (77.7%), and 71 (80.7%) patients in the CR, PR, and SD groups, respectively. In the CR group, the most common reason for treatment discontinuation, observed in 12 (42.9%) of the 28 patients, was achievement of CR. In the PR and SD groups, the most common reason was disease progression, occurring in 86.4% and 83% of patients, respectively.
The CR, PR, and SD groups were similar with respect to median age (65, 63, and 64 years, respectively). Clear cell carcinoma was the predominant histologic subtype; it was present in 92.9%, 97.1%, and 95.5% of the CR, PR, and SD groups.
The investigators acknowledged limitations of the study, including the retrospective design and lack of independent validation of treatment responses.
Buchler T, Poprach A, Bortlicek Z, et al. Outcomes of patients with long-term treatment response to vascular endothelial growth factor-targeted therapy for metastatic renal cell cancer. Clin Genitourin Cancer 2017; published online ahead of print. doi: 10.1016/j.clgc.2017.06.006