A maintenance therapy regimen comprising oral cyclophosphamide plus celecoxib has demonstrated feasibility in patients with metastatic Ewing sarcoma, according to data being presented at the virtual 2020 ASCO Annual Meeting.

Nadia Puma, MD, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy, and colleagues conducted the ISG/AIEOP EW2 Study to assess the feasibility and efficacy of cyclophosphamide plus celecoxib as maintenance therapy for patients with metastatic Ewing sarcoma.

Between June 1, 2009, and November 22, 2019, a total of 112 patients with metastatic Ewing sarcoma were enrolled in the study and given induction chemotherapy, radiotherapy, and/or surgery at the site of the primary tumor; a consolidation phase with high-dose busulphan/melphalan plus autologous stem cell rescue; whole-lung irradiation 12 Gy to 15Gy; and a maintenance phase of cyclophosphamide 50 mg daily for 180 days (35 mg/mq daily if <14 years) plus celecoxib 400 mg twice daily (250 mg/mq twice daily if <14 years).

Patients with disease progression, cardiac comorbidity, or gastrointestinal comorbidity were excluded from the maintenance phase of the trial. Temporary interruptions were planned for any patents who had grade 3-4 toxicities a temporary interruption was planned.

Ultimately, 71 patients (median age, 16 years) were deemed eligible for the maintenance phase of the study. The majority (n = 56) of these patients had metastases of the lung or single bone and 15 had multicentric metastatic spread.

Maintenance therapy was halted in 61 patients, and 4 are still receiving treatment. One patient had therapy interrupted because of auto-immune thrombocytopenia at 4 months, and 5 patients withdrew from the maintenance phase because of disease progression/relapse.

Maintenance therapy lasted for 89% of the scheduled days, and patients had a median suspension length of 12 days. Temporary suspensions that occurred were attributed to hematologic toxicities (19 episodes), infections (12 episodes), gastrointestinal disorders (9 episodes), fluid retention/distal edema (3 episodes), and renal disorders (3 episodes).

The median follow-up time frame was 42 months. Patients in the maintenance phase had a 3-year EFS of 0.79 ± 0.09 if they had metastases of the lung or single bone and 0.19 ± 0.11 if they had multicentric metastatic spread.

“This schedule of maintenance phase is feasible, despite previous intensive treatment. A longer follow-up is needed to monitor side effects and to evaluate clinical outcome of patients with lung or single bone metastases, while the outcome remains dismal for multicentric metastatic Ewing sarcoma,” Dr Puma and colleagues concluded.—Hina M. Porcelli

Puma N, Sebastian AD, Paioli A, et al. Maintenance therapy with oral cyclophosphamide plus celecoxib in patients with metastatic Ewing sarcoma: Results of the Italian Sarcoma Group/AIEOP EW-2 study. Presented at: the 2020 ASCO Annual Meeting; May 29-31, 2020. Abstract 10517.