Geoerger B, Zwaan CM, Marshall LV, et al. - Researchers tested atezolizumab, an inhibitor of PD-L1, in children and young adults with refractory or relapsed solid tumours, with known or expected PD-L1 expression, to determine its safety, pharmacokinetics, and activity in these patients enrolled in a multicentre, open-label, phase 1–2 trial, named iMATRIX. This trial included patients (aged < 30 years) with solid tumours or lymphomas selected from 28 hospitals in ten countries (USA, France, Italy, UK, Spain, the Netherlands, Denmark, Israel, Switzerland, and Germany). In this study, 15 mg/kg atezolizumab (maximum 1200 mg) was administered to eligible patients younger than 18 years; the adult dose (1200 mg) was administered to patients aged 18–29 years until disease progression or loss of clinical benefit. Enrolled patients (with a median age of 14 years) were 90 in total. Pyrexia and fatigue were identified as the most common adverse events that occurred in the safety-evaluable population (n = 87). Anaemia was detected as the most common grade 3–4 adverse event. No fatal adverse events were reported. All patients exhibited serum levels of atezolizumab above the target exposure level. An objective response (all partial responses) was attained by four patients (5%) at 6 months. Findings revealed restricted response to atezolizumab, as well as good tolerability of atezolizumab with generally comparable exposure across populations.