Phase I and pharmacokinetic study of IHL-305 (PEGylated liposomal irinotecan) in patients with advanced solid tumors

Purpose

IHL-305 is a novel PEGylated liposome containing irinotecan. This study examined the safety profile and pharmacokinetics of IHL-305 and established the maximum tolerated dose and recommended phase II dose (RP2D).

Patients and methods

In a standard 3?+?3 design, IHL-305 was administered IV on day 1 of a 28-day treatment schedule. Subsequently, a 14-day treatment schedule was also explored. Two patient populations were evaluated separately: Patients with at least one wild-type (wt) allele of UGT1A1 (UDP glucoronosyltransferase 1A1) wt/wt or wt/*28 as one group (referred to as UGT1A1 wt group) and patients with UGT1A1*28 homozygous variant (*28/*28) as another group.

Results

Sixty patients were treated: 42 on the 28-day schedule and 18 on the 14-day schedule. Seven patients were homozygous variant (*28/*28). In the UGT1A1 wt group, the MTD and RP2D of IHL-305 was 160?mg/m² every 28?days and 80?mg/m² every 14?days. DLTs included nausea, vomiting, diarrhea, and neutropenia. The most common adverse events were nausea (75?%), vomiting (52?%), diarrhea (62?%), anorexia (57?%), and fatigue (57?%). At the MTD for both schedules, IHL-305 administration resulted in a high and prolonged exposure of sum total irinotecan, released irinotecan, and SN-38 in plasma. One partial response was observed in a patient with breast cancer and eight patients had stable disease for >6?months.

Conclusions

IHL-305, a novel preparation of irinotecan encapsulated in liposomes, can be safely given to patients in a repeated fashion on a 4- or 2-week dosing schedule.