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The following is a summary of “Phase II Trial of Risk-Enabled Therapy After Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer (RETAIN 1),” published in the December 2024 issue of Oncology by Geynisman et al.
Cisplatin-based neoadjuvant chemotherapy (NAC) followed by cystectomy is the standard treatment for people with muscle-invasive bladder cancer (MIBC). Mutations in DNA damage repair genes are linked to pathologic downstaging after NAC.
Researchers conducted a prospective study to evaluate a risk-adapted approach to treatment for people with MIBC after NAC.
They enrolled people with clinical stage cT2-T3N0M0 MIBC who underwent NAC with accelerated methotrexate, vinblastine, doxorubicin, and cisplatin (AMVAC). Pre-treatment tumor samples were sequenced for mutations in ATM, ERCC2, FANCC, and RB1 genes. People with mutations and clinical stage T0 after NAC began active surveillance (AS). The primary endpoint was metastasis-free survival (MFS) at 2 years, with the null hypothesis rejected if the lower bound of the 95% CI exceeded 64%.
The results showed that 70 people had mutations, 33 (47%), and 25 (36%) began AS. The 2-year MFS for the entire group was 72.9% (lower bound exact one-sided 95% CI, 62.8). The MFS was 76.0% (95% CI, 54.2 to 88.4) in the AS group and 71.1% (95% CI, 55.5 to 82.1) in the non-AS group. In the AS group, 17 people (68%) had some recurrence, and 12 (48%) remained metastasis-free with an intact bladder. The 2-year OS was 84.3% (95% CI, 73.4 to 91.0), OS was 88.0% (95% CI, 67.3 to 96.0) in the AS group and 82.2% (95% CI, 67.6 to 90.7) in the non-AS group.
They concluded that a risk-adapted approach to MIBC after NAC resulted in 73% MFS at 2 years, with 48% of people in the AS group avoiding cystectomy without metastatic disease.
Source: ascopubs.org/doi/10.1200/JCO-24-01214
