3359 - The Role of Stereotactic Body Radiotherapy in Oligoprogressive Renal Cell Carcinoma: A Site-Specific Analysis of the Phase II RADIANT Trial
Presenter(s)
N. K. Rastogi1, A. Barry2,3, J. Helou4,5, X. Y. Ye6, P. Chung1,7, K. M. Ruicci1, A. Berlin1,7, C. Catton1,7, E. Gutierrez1,7, A. Mesci1,8, A. McPartlin1,7, B. Id Said1,7, S. Raman9,10, J. Winter7,11, J. Dang7, N. Fallah-Rad12,13, V. Kumar12,13, S. S. Sridhar12,13, and R. Glicksman1,7; 1Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada, 2University College Cork, Cork, Ireland, 3Cork University Hospital, Cork, Ireland, 4Verspeeten Family Cancer Centre, London Health Sciences Centre, London, ON, Canada, 5Division of Radiation Oncology, Western University, London, ON, Canada, 6Department of Biostatistics, University Health Network, Toronto, ON, Canada, 7Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada, 8Princess Margaret Hospital, UNH, University of Toronto, Toronto, ON, Canada, 9Radiation Oncology, BC Cancer, Vancouver, BC, Canada, 10Department of Surgery, The University of British Columbia,, Vancouver, BC, Canada, 11Department of Medical Physics, Princess Margaret Cancer Centre, Toronto, ON, Canada, 12Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, Toronto, ON, Canada, 13Department of Medicine, University of Toronto, Toronto, ON, Canada
Purpose/Objective(s):
For progressive metastatic renal cell carcinoma (mRCC), the standard approach has been to change systemic therapy, often at the expense of additional toxicity, costs, and limited subsequent options. Stereotactic body radiation therapy (SBRT) is increasingly explored as a strategy to ablate limited sites of disease progression (‘oligoprogression’), thus prolonging effective systemic therapy. Here, we analyze clinical, toxicity and health-related quality of life (HRQOL) data for an oligoprogressive mRCC cohort from the prospective RADIANT clinical trial (NCT04122469).Materials/Methods:
RADIANT is a single-arm, phase II basket trial of patients with metastatic cancers, including mRCC, on systemic therapy >3 months with radiographic oligoprogression in <5 sites. Analysis by primary histology was planned a priori. Patients received SBRT (1-5 fractions) to all progressive sites and continued their current systemic therapy. The primary endpoint was time to systemic therapy change (measured from SBRT start date), analyzed using cumulative incidence methods. Secondary endpoints included local control, adverse events (CTCAE v5.0), and HRQOL (EORTC QLQ-C30; minimal clinically important difference (MCID) defined as 10-point change from baseline).Results:
Twenty-two patients with mRCC were analyzed; 16 (72%) had clear cell histology. Median age was 67.5 years, 23% were women and 55% had de novo mRCC. Most patients (55%) were on first line systemic therapy, 27% were on second line, and 14% were on third line. Most common systemic therapy at time of enrollment was combination immunotherapy and targeted agent (36%), targeted agent alone (36%), or immunotherapy alone (18%). Most patients (n=20; 91%) had 1-3 oligoprogressive sites, of which twelve (55%) had a single one. Metastasis locations were predominantly visceral (n=15; 68%). SBRT was most commonly delivered as 30-40 Gy in 5 fractions (n=16; 73%), with a mean treated gross tumor volume (GTV) of 39cc. At a median follow-up of 13.8 months (IQR 10.6-27.7), 71.5% (95% CI 42.5-85.9%) of patients remained on the same systemic therapy at 1-year. One-year local control was 80.7% (95% CI 51.8-92.2%). There was 1 instance of acute grade 2 chest wall pain with no grade =3 adverse events. Mean decrease in HRQOL at 6 months was 7.6 pts which did not reach threshold for MCID.Conclusion:
In this prospective phase 2 cohort, SBRT for oligoprogressive mRCC enabled approximately three-quarters of patients to remain on their current systemic therapy at 1 year, with favourable local control, minimal toxicity and preserved HRQOL. These findings support the strategy of local ablative therapy to prolong effective systemic therapy and warrant validation in randomized trials.