Irinotecan and temozolomide chemotherapy in paediatric and adult populations with relapsed Ewing Sarcoma

Background Irinotecan and temozolomide (IT) is a widely used regimen for relapsed Ewing sarcoma (ES), although studies are largely limited to paediatric populations. Methods We retrospectively reviewed paediatric (< 18 years) and adult patients (>= 18 years) treated with salvage IT at two institutions. Haematologic toxicities were graded according to common terminology criteria of adverse events. Survival was estimated by the Kaplan-Meier method and compared by the Log Rank test. Results Fifty-three patients were treated with IT from Jan, 2010 to Dec, 2018 (n = 16 paediatric;n = 37 adult). IT was given as second-line (n = 34; 64%) or >= third-line (n = 19; 36%). There was no difference in >= grade 3/4 haematologic toxicity between paediatrics and adults (31% vs. 35% respectively;p = 0.76). The frequency of diarrhoea of any grade was similar (38% in each group). Of 43 patients assessable for response, 12 (28%) had objective response (1 CR, 11 PR), 12 (28%) stable disease and 19 (44%) disease progression. Objective response rate did not differ between the two groups (36% in paediatrics vs. 25% in adults;p = 0.47). Median PFS was superior in paediatrics vs. adults (7.4 vs. 2.2 months,p = 0.039). Conclusion Irinotecan and temozolomide (IT) chemotherapy has activity for relapsed ES, with favourable toxicity and equally observed objective responses in the paediatric and adult populations. The observed superior PFS for the paediatric cohort requires further confirmation in future studies.

Automated summary

Irinotecan and temozolomide (IT) chemotherapy shows similar efficacy and favorable toxicity in pediatric and adult patients with relapsed Ewing sarcoma, with superior median progression-free survival (PFS) observed in the pediatric cohort. The results suggest that IT regimen is effective for relapsed ES in both pediatric and adult populations.