Outcomes of relapsed favorable-histology Wilms tumor in non-clinical trial setting

The last major North American cooperative group clinical trial for relapsed favorable-histology Wilms tumor (FHWT) was completed in 2002. The outcomes of patients with relapsed Wilms tumor subsequently treated outside of clinical trials are unknown. The aim of this study was to assess the efficacy and toxicity of salvage therapies used for patients with FHWT suffering first relapse.

We conducted a retrospective chart review of patients treated for first relapse of FHWT at six large North American institutions from January 2002 through August 2018.

Ninety-four patients were identified. Thirty-six patients were classified as standard-risk relapse (SRR), 49 patients as high-risk relapse (HRR), and seven patients as very high-risk relapse (VHRR). Two patients were unable to be classified. Twenty-one patients with SRR were treated with Regimen I. The 4-year event-free survival (EFS) and overall survival (OS) for SRR were 82.4% and 93.3%, respectively, with median follow-up of 72 months. Twenty-eight HRR/VHRR patients were treated with ICE therapy, while 13 received National Wilms Tumor Study (5th) (NWTS-5) Stratum C. No patient completed protocol therapy per Stratum C; median maintenance cycles administered were two cycles. The 4-year EFS and OS for HRR/VHRR were 32.6% and 58.3%, respectively, with median follow-up of 33 months.

Outcomes for all strata of relapsed WT patients treated in a non-clinical setting appear to have similar outcomes to historical cohorts treated on NWTS-5. Improved strategies are urgently needed for HRR and VHRR relapses.