Physician Treatment Selection in the Prospective Metastatic Renal Cell Cancer (MaRCC) Registry

Characteristics of patients enrolled in clinical trials of metastatic renal cell carcinoma (mRCC) can often differ from those in the real world setting, resulting in potential bias in the literature. The MaRCC Registry is designed to survey questions not asked in trials, such as what practicing physicians choose as first-line therapy among many available options, and why physicians make certain management decisions. This analysis describes physician treatment selection of first line therapy and reasons for treatment selection in 502 real world patients enrolled in a multicenter, prospective, observational registry.

The MaRCC Registry enrolled 502 patients from 46 US academic (ACAD) (N=20) and community (N=26) sites with mRCC and no prior systemic therapy for metastatic disease. Key endpoints included descriptive treatment characteristics (e.g. treatment agents, sequence, duration, reasons for therapy choice and discontinuation), treatment effectiveness (e.g. overall response rate, progression free survival (PFS), overall survival (OS)), quality of life as collected via patient reported outcomes, medication adherence, ability to work, hospitalizations, and emergency department visits. Here we describe preliminary results from the physician surveys conducted at the time of study enrollment.

At data cut-off of August 4, 2017, 502 patients had been accrued: median age 63 (Q1-3 range, 56-70); 70% male; 75% ACAD; 78% clear cell histology; and 33% stage IV at diagnosis. Initial management decision was: 59% (294) went directly on systemic therapy (ST), whereas in 41% (208) systemic therapy was deferred (DST). At time of data cut-off and through a median follow-up of 8.5 months, 73/208 (35%) of the DST patients started ST. For all patients treated with ST (367) in the registry, first line treatments included pazopanib (45%), sunitinib (21%), clinical trial (19%), and high-dose interleukin-2 (5%). The most common categories for therapy choice as selected by providers were likelihood of clinical benefit (61%) followed by patient characteristics (25%). Within the clinical benefit category, the most common reason was OS/PFS (37%), followed by likelihood of tumor regression (27%). Within the patient characteristic category the most common reasons included prognostic factors (12%) or performance status/frailty (7%). In the DST group, ECOG 0 was seen in 46% and in ST, 35%. For first line ST, the mean and median starting pazopanib dose was 684 mg and 800 mg respectively, with 114/164 patients (69.5%) starting at full dose (800 mg). The mean and median starting sunitinib dose was 49 mg and 50 mg respectively, with 70/79 patients (88.6%) starting at full dose (50 mg).

This is the first prospective report of physician practice patterns in the first line treatment of mRCC patients in the real world setting. We describe the most common factors driving physician decision making in management of mRCC. Early experience suggests that clinical benefit associated with treatment and patient characteristics were the most common reasons for initial ST selection. Interestingly, side effect profile rarely determined initial ST selection.