Palbociclib and ganitumab combo shows limited efficacy for relapsed Ewing sarcoma

The combination therapy of palbociclib and ganitumab in Ewing sarcoma (EWS) did not demonstrate sufficient therapeutic activity to warrant further investigation, according to a study. However, a subset of patients experienced prolonged stable disease.

The Phase 2 trial was an open-label, non-randomized study that enrolled patients aged ≥12 years who had confirmed molecular diagnosis of EWS and measurable disease according to RECIST criteria. The treatment regimen consisted of oral palbociclib (125 mg) on Days 1-21 and intravenous ganitumab (18 mg/kg) on Days 1 and 15 of a 28-day cycle. The primary endpoints of the study were objective response (complete or partial) according to RECIST criteria and toxicity assessment using CTCAE.

A total of 10 evaluable patients were enrolled in the study, with a median age of 25.7 years. The median duration of therapy was 2.5 months (ranging from 0.9 to 10.8 months).

There were no complete or partial responders among the patients. However, 3 out of 10 patients experienced stable disease for more than 4 cycles, and 2 patients had stable disease until completion of the planned therapy or study closure. The 6-month progression-free survival rate was 30% (95% CI 1.6% – 58.4%).

Reference
Shulman DS, Merriam P, Choy E, et al. Phase 2 trial of palbociclib and ganitumab in patients with relapsed Ewing sarcoma. Cancer Med. 2023 Jun 12. doi: 10.1002/cam4.6208. Epub ahead of print. PMID: 37306107.