High-Dose Methotrexate Usage Without Drug-Level Monitoring in Advanced Pediatric Mature B-Cell Non-Hodgkin Lymphoma...

Excellent survival for advanced (stages II with high lactate dehydrogenase, III, and IV) pediatric mature B-cell non-Hodgkin lymphoma (MB-NHL) has been achieved with intensive regimens, but adoption in sub-Saharan Africa is limited by inadequate supportive care. We provide real-world data on treating advanced MB-NHL with high-dose methotrexate (HD-MTX; ≥1,000 mg/m²/cycle) where real-time serum MTX monitoring is unavailable.

We identified two cohorts-a retrospective (January 2017-December 2020) cohort treated with 1,000 or 3,000 mg/m²/cycle of HD-MTX and a prospective (July 2022-July 2023) cohort-with a modified LMB96 protocol containing 3,000 mg/m²/cycle of HD-MTX. All doses of HD-MTX were given over 3 hours. Estimates of 12-month event-free survival (EFS) and overall survival (OS) were calculated with abandonment as an event. Clinical toxicity data were available for the prospective cohort.

The retrospective cohort had 108 patients who received HD-MTX 1,000 mg/m² (n = 98, 91%) or 3,000 mg/m² per cycle. The 12-month EFS and OS were 39% (95% CI, 30 to 50) and 54% (95% CI, 44 to 64), respectively. HD-MTX at 3,000 mg/m² had superior EFS: 69% (95% CI, 49 to 96) versus 33% (95% CI, 24 to 46), P = .004. The prospective cohort had 38 patients. Two ≥grade 3 mucositis, one acute kidney injury, and three treatment-related deaths (8%) occurred. Seven (18%) abandoned treatment. With a median follow-up of 14.5 months, 12-month EFS and OS were 45% (95% CI, 32 to 65) and 59% (95% CI, 45 to 79), respectively. Most relapses were stage IV: EFS 20% versus 51% (non-stage IV; P = .057). Severe malnutrition was associated with OS of 33% versus 58% (normal) or 76% (moderate; P = .055).

HD-MTX dosed at 3,000 mg/m²/cycle is feasible in low-resource settings where routine MTX monitoring is unavailable. Stage IV disease and severe malnutrition may contribute to poorer outcomes.