Phase II study of nivolumab and ipilimumab in children and young adults with INI1-negative cancers.

Abstract

TPS10055 Background: Several aggressive pediatric and young adult cancers are characterized by SMARCB1 inactivation resulting in loss of INI1 expression, including rhabdoid tumors, epithelioid sarcoma and undifferentiated chordoma. These malignancies are associated with a poor prognosis and few effective treatment options for relapsed or refractory disease. Prior studies and emerging data suggest INI1-negative cancers may be uniquely susceptible to treatment with immune checkpoint inhibitors: Many INI1-negative pediatric tumors express PD-L1 and are infiltrated by immune cells, and there are reports of patients with advanced INI1-negative cancers with clinical responses to immune checkpoint blockade (Forrest et al. Clinical Cancer Research, 2020). We hypothesize that INI1 loss predicts tumor response to immune checkpoint inhibition (ICI). Methods: This is an ongoing multicenter, phase II, open-label clinical trial to evaluate the activity of nivolumab and ipilimumab in patients aged 6 months to 30 years with relapsed or refractory INI1-negative cancers (NCT04416568). The study enrolls patients in 2 strata: extracranial solid tumors in Stratum 1 and intracranial solid tumors in Stratum 2. Patients treated with prior ICI are excluded. Patients are treated with intravenous (IV) nivolumab 3mg/kg plus ipilimumab 1mg/kg IV every 3 weeks for 4 cycles followed by nivolumab 3mg/kg (max dose 240mg) IV every 2 weeks for up to 1-year. The primary objective is to evaluate the objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors (RECIST) for Stratum 1 and by Response Assessment in Neuro-Oncology (RANO) criteria for Stratum 2. The trial has a 2-stage design targeting a 25% or greater response rate, with each stratum assessed independently. The analysis for Stage 1 in a given Stratum will be performed after 10 patients are enrolled. If a sufficient number of responders are observed, an additional 10 patients will be enrolled at Stage 2. Secondary endpoints include progression-free survival, overall survival, and disease control rate at 12 months. Correlative aims include assessing tissue and blood biomarkers associated with treatment response. Enrollment began 14 Aug 2020 and is ongoing. Clinical trial information: NCT04416568.