Inhibrx has reported initial findings from the Phase I clinical trial of INBRX-109 plus Irinotecan and Temozolomide (IRI/TMZ) to treat advanced or metastatic, unresectable Ewing sarcoma (EWS).
The trial analysed the safety and efficacy of the combination treatment for EWS, a rare, aggressive tumour that occurs in adults and children.
According to trial data from 13 evaluable subjects, a 76.9% disease control rate, as measured by RECISTv1.1, was reported.
These subjects comprise seven classical EWS patients and six round-cell sarcoma patients (RCS).
Furthermore, 53.8% of patients attained partial responses of which 71.4% were classical EWS and 33.3% were RCS patients.
Durable clinical benefit was reported in 30.8% of participants who attained disease control that was sustained for more than six months.
As of 8 September 2023, the longest period of stable condition was more than ten months.
In the trial, the combination treatment was also found to be well tolerated with diarrhoea, nausea and fatigue reported as the most frequently seen adverse events.
These adverse events were in line with the already reported safety profile of IRI/TMZ.
No Grade 3 or higher liver-associated events were observed in the trial.
A tetravalent death receptor 5 (DR5) agonist antibody, INBRX-109 is designed for exploiting the tumour-biased cell death caused by activation of DR5.
The US Food and Drug Administration (FDA) awarded fast track designation to INBRX-109 in January 2021 to treat unresectable or metastatic conventional chondrosarcoma. The antibody also received orphan drug status for treating chondrosarcoma.
