Phase I dose-escalation study to determine the safety, tolerability, preliminary efficacy and pharmacokinetics of an intratumoral injection of tigilanol tiglate (EBC-46)

Tigilanol tiglate, a short-chain diterpene ester, is being developed as intratumoral treatment of a broad range of cancers. We conducted the first-in-human study of intratumoral tigilanol tiglate in patients with solid tumors. Tigilanol tiglate was administered in a multicentre, non randomized, single-arm study, with escalating doses beginning with 0·06 mg/m 2 in tumors estimated to be at least twice the volume of injection (dose-escalation cohorts). Patients with smaller tumors were assigned to the local effects cohort and received the appropriate dose for tumor size. Twenty-two patients were enrolled. The maximum dose was 3·6 mg/m 2 and the maximum tolerated dose was not reached. There was one report of dose-limiting toxicity (upper airway obstruction), two serious adverse events (upper airway obstruction and septicemia), 160 treatment-emergent adverse events, and no deaths. Injection site reactions in all tumors and tumor types occurred even at the lowest dose. Six of the 22 patients experienced a treatment response, with four of the six patients achieving complete response. Intratumoral tigilanol tiglate was generally well tolerated, the maximum tolerated dose was not reached, and clinical activity was observed in 9 tumor types including complete response in four patients. These results support the continued development of tigilanol tiglate for intratumoral administration. QBiotics Group Limited Brisbane, Queensland, Australia was the sponsor of the study.