Rhabdoid Tumor of the Kidney and Soft Tissues: Results from National Wilms Tumor Study-5 and Children's Oncology Group Study AREN0321.

Abstract

Purpose: National Wilms Tumor Study-5 (NWTS-5) and AREN0321 evaluated the outcomes of children with rhabdoid tumor of the kidney (RTK) and malignant rhabdoid tumor of soft tissues (MRT).

Patients and methods: Eligible patients with RTK were enrolled prospectively on NWTS-5 (1995-2002) and treated with carboplatin and etoposide alternating with cyclophosphamide (Regimen RTK). Patients with RTK or MRT were enrolled on AREN0321 (2005-2012) and received vincristine, doxorubicin, and cyclophosphamide alternating with carboplatin, cyclophosphamide, and etoposide (Regimens UH-1 or dose-reduced Revised UH-1). We report event-free survival (EFS) and overall survival (OS) from each study.

Results: Thirty patients received Regimen RTK on NWTS-5; on AREN0321, 20 received UH-1 and 19 received Revised UH-1. Patient and disease characteristics were statistically similar between studies. Patients on AREN0321 had significantly improved EFS and OS compared to those on NWTS-5 (4-year EFS = 23.1% vs. 16.7%; p = 0.020; 4-year OS = 30.6% vs. 20.0%; p = 0.014), mostly driven by patients with Stage I/II disease (p = 0.05). Median time to an event was 3.6 months on NWTS-5 compared to 7.2 months on AREN0321. There were no differences in EFS or OS by revised versus original Regimen UH-1 on AREN0321, or by renal versus extra-renal primary disease when the studies were pooled.

Conclusions: The more intensive treatment regimen used on AREN0321 improved EFS and OS overall, a result driven by patients with Stage I/II disease. Despite this improvement, outcomes for patients with rhabdoid tumor remain unsatisfactory and there is a need for novel therapeutic strategies.