Treatment-specific patient characteristics and outcomes may change over time with new information and approved treatments. Real-world data analyses aimed at informing clinical decision-making must account for non-random treatment assignment by physicians. Treatment pattern changes in 1L mRCC across periods defined by approved therapies have not been described in mRCC.

A retrospective cohort study of newly diagnosed mRCC patients initiating FDA-approved systemic treatment was conducted within the de-identified Optum Clinformat-ics^™administrative claims database and stratified by year of treatment initiation. Counts and proportions of patients assigned to first (1L) systemic treatment, patient characteristics and duration of therapy were determined. Significance testing was not performed. Results for current 1L SOC treatments, sunitinib and pazopanib, are highlighted.

Following pazopanib approval (2009-2011), sunitinib- and pazopanib-treated patients numerically differed in age (62.4±9.8 years vs. 59.7±10.7 years; age≥65, 38.1% vs 35.2%), region (46.7% vs 63.0% South) and complete nephrectomy within 6 months of initiating therapy (22.7% vs. 31.5%). Gender, insurance, comorbidity index, pre-index inpatient hospital admissions (RCC and overall) were similar. During 2012-2014, the pattern persisted with the proportion of elderly (age ≥65, 59.1% vs 49.8%) and Medicare-insured (51.5% vs 41.8%) sunitinib patients increasing. In 2015-2016, sunitinib patients had a lower average age than pazopanib patients (age 64.9±11.0 vs 67.5±11.2, ≥65, 49.7% vs 62.6%), a higher proportion males (74.9% vs 66.7%), more pre-index RCC-hospitalizations (47.2% vs 39.6%), lower Medicare (45.7% vs 55.4%), and similarly complete nephrectomy proportions (34.7% vs 37.8%).

Treatment-specific duration of therapy (DoT) measures changed over time. During 2006-2008, 32.9% and 10.6% of sunitinib initiators remained on therapy at 6 and 12 months, respectively, compared with 26.0% and 8.6% in 2009-2011, 30.0% and 9.7% in 2012-2014 and 25.1% and 7.0% during 2015-2016. During 2009-2011, pazopanib-treated patients’ DoT at 6 and 12 months were 35.2% and 18.5%; falling to 26.2% and 12.9% in 2012-2014 and 27.9% and 7.7% in 2015-2016.

The study results demonstrate that 1L mRCC baseline patient demographics and treatment patterns have evolved over time given the rapidly changing treatment environment that saw three targeted mRCC therapies in 2007 to ten available in mid-2017. Specific reasons and implications of why baseline patient characteristics have changed over time requires future research; however, given these results, real-world data studies in mRCC should evaluate the need for matching patient characteristics and accounting for temporal impact of when the patient initiated treatment. Without these adjustments, RWD studies in mRCC may be confounded and lead to biased results.