ARST2032: A Prospective Phase 3 Study of Patients with Newly Diagnosed Very Low-risk and Low-risk Fusion Negative Rhabdomyosarcoma

Patients with low-risk rhabdomyosarcoma (LR-RMS) have excellent outcomes with 4-year event free survival (EFS) rates of approximately 90% when treated on recent North American trials (D9602 and ARST0331). Molecular prognostic features have recently been described for fusion negative RMS but have yet to be incorporated into a prospective clinical trial. By reclassifying patients with LR-RMS who have adverse molecular features (TP53 or MYOD1 mutations), the LR-RMS group may be enriched with patients with a more favorable prognosis. This study will redefine patients with LR-RMS into two subgroups: 1) very low-risk (VLR): Patients with fusion negative (FN), Stage 1/CG I disease with MYOD1/TP53 wildtype (WT) tumors, and 2) low-risk (LR): Patients with Stage 1/CG II, or Stage 2/CG I/II or CG III (orbit only) disease with MYOD1/TP53 WT tumors. Patients with VLR-RMS will be treated with 24 weeks of VA therapy, representing both a reduction in the duration of therapy compared to that used in D9602 as well as an elimination of any alkylating agent as used in ARST0331. Patients with LR- RMS will be treated with 12 weeks of VAC followed by 12 weeks of VA with the goal of achieving superior outcomes in this now enriched population (MYOD1/TP53 WT). For patients with clinically defined VLR or LR disease whose tumors harbor pathogenic MYOD1 or TP53 mutations, therapy will be escalated to 42 weeks of VAC therapy.