Citius Oncology (NASDAQ:CTOR) reported positive topline results on Tuesday from an investigator-initiated Phase 1 clinical trial evaluating its flagship immunotherapy, LYMPHIR (denileukin diftitox-cxdl), in combination with Merck’s pembrolizumab (Keytruda).
The study focused on patients with relapsed or refractory gynecologic cancers, including ovarian and endometrial malignancies, who have historically limited options after failing standard chemotherapy.
The trial, led by investigators at the University of Pittsburgh, demonstrated a manageable safety profile with no unexpected safety signals or serious immune-related adverse events across escalating dose levels.
Among 21 efficacy-evaluable patients, the combination produced a 24% objective response rate (ORR) and a 48% clinical benefit rate (CBR).
These metrics are particularly notable in a heavily pretreated population, where sustained disease control is difficult to achieve with checkpoint inhibitors alone.
LYMPHIR, which received FDA approval in December 2025 for cutaneous T-cell lymphoma, works by transiently depleting T-regulatory (Treg) cells—immunosuppressive cells that often help tumors evade the immune system.
By clearing these "shield" cells, LYMPHIR appears to augment the anti-tumor activity of pembrolizumab.
Management stated that the data supports the transition to a Phase 2 study to further evaluate the combination's potential as a non-chemotherapy alternative.
Full results from the Phase 1 trial are scheduled for presentation at an international cancer conference later this year.