Background
Phase II randomized study (within ALCL99 backbone). 66 pediatric patients (≤21 years) with newly diagnosed ALK-positive anaplastic large cell lymphoma (ALK+ ALCL). ALK+ ALCL in children harbors NPM1-ALK or variant fusions driving constitutive ALK kinase activity. Crizotinib is a first-generation ALK/MET/ROS1 inhibitor. ANHL12P1 was the first trial testing crizotinib combined with standard chemoimmunotherapy in pediatric ALK+ ALCL.
Interventions and follow up
Arm A: Crizotinib 165 mg/m² PO BID on days 1–21 of each cycle + standard ALCL chemotherapy backbone (ALCL99) × 6 courses
Arm B: ALCL99 chemotherapy backbone alone (same 6-course schedule, no crizotinib)
Primary endpoint: 2-year event-free survival (EFS)
Median follow up: 3.9 years
Arm B: ALCL99 chemotherapy backbone alone (same 6-course schedule, no crizotinib)
Primary endpoint: 2-year event-free survival (EFS)
Median follow up: 3.9 years
Results
2-year EFS (crizotinib): 76.8% vs ~50% historical ALCL99 control
2-year OS: 95.2%
ORR at end of induction: 94%
Thromboembolic events: 19.7% in crizotinib arm (grade 3–4 13%)
2-year OS: 95.2%
ORR at end of induction: 94%
Thromboembolic events: 19.7% in crizotinib arm (grade 3–4 13%)
Adverse events
Thromboembolic: Venous thromboembolism 19.7% (grade ≥3 14%); 3 VTE-related deaths
Hematologic/other: Grade ≥3 neutropenia 45.5%; grade ≥3 hepatotoxicity 10.6%; vision changes (photopsia) 18.2%
Hematologic/other: Grade ≥3 neutropenia 45.5%; grade ≥3 hepatotoxicity 10.6%; vision changes (photopsia) 18.2%
Conclusions
Crizotinib + chemotherapy achieved a 2-year EFS of 76.8% in pediatric ALK+ ALCL, substantially better than historical ALCL99 results (~50% EFS). However, thromboembolic events were a major unexpected toxicity (19.7%), leading to mandatory thromboprophylaxis recommendations for subsequent use.
Key Limitations
Comparison was to historical ALCL99 control rather than a concurrent randomized control arm, making efficacy interpretation indirect. The high rate of thromboembolic events (19.7%), including 2 treatment-related VTE deaths, was unexpected and requires mandatory prophylactic anticoagulation. Crizotinib dosing in children and chemotherapy interactions require specialized pediatric oncology expertise. Longer follow-up and next-generation ALK inhibitors (alectinib, lorlatinib) remain under investigation.
Clinical Context
FDA approved crizotinib for pediatric R/R ALK+ ALCL in 2021; frontline combination remains off-label. Based on ANHL12P1, crizotinib + chemotherapy with mandatory thromboprophylaxis is used at many pediatric centers, with a clinically meaningful 2-year EFS improvement (76.8% vs ~51%). Next-generation trials are testing lorlatinib (CNS-penetrant ALK/ROS1 inhibitor) in R/R pediatric ALK+ ALCL.
References