The following article features coverage from the American Society of Clinical Oncology 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Irinotecan and temozolomide (IT) led to inferior clinical outcomes for patients with recurrent and primary refractory Ewing sarcoma (RR-ES), according to the results of the second interim assessment of the multiarm randomized phase 2/3 rEECur trial. The trial results were reported at the ASCO20 Virtual Scientific Program.

A total of 366 patients with RR-ES were randomly assigned to 1 of 4 chemotherapy regimens: topotecan and cyclophosphamide (TC), IT, gemcitabine and docetaxel (GD), or high-dose ifosfamide (IFOS).

Accrual to the GD arm was stopped when the first interim assessment revealed worse objective response (OR) and poorer progression-free survival (PFS) for the regimen.

For the second interim assessment, the outcomes of the IT arm were compared to the outcomes of the other open treatment arms — TC and IFOS — but to maintain blinding, the other arms were randomly labeled as A and B.


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In all comparisons of outcomes, the patients in the IT arm had worse outcomes than those in the other treatment arms.

More specifically, there was a less than 50% probability that those in the IT arm had a higher OR than those in arm A or arm B. Regarding PFS, individuals in the IT arm had only a 7% probability of seeing prolonged PFS compared with individuals in arm A and 33% probability of longer PFS compared with arm B. As for OS, the patients in the IT arm had a 32% probability of prolonged OS compared with those in arm A and a 38% probability compared with arm B.

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Participants in the IT arm had a similar frequency of grade 3 or higher adverse events (41%) compared with those in arms A and B combined (42%) and worse nausea, vomiting, diarrhea, and colitis. However, people in the IT arm did have fewer instances of febrile neutropenia and fewer infections.

“Irinotecan and temozolomide is less effective than topotecan and cyclophosphamide and high-dose ifosfamide in achieving imaging response, progression-free [survival], and overall survival,” said study presenter Martin G. McCabe, PhD, University of Manchester, Manchester, United Kingdom.

Arms TC and IFOS continue to enroll patients.

Read more of Cancer Therapy Advisor‘s coverage of the ASCO 2020 meeting by visiting the conference page.

Reference

McCabe MG, Kirton L, Khan M, et al. Results of the second interim assessment of rEECur, an international randomized controlled trial of chemotherapy for the treatment of recurrent and primary refractory Ewing sarcoma (RR-ES). Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr 11502.