A phase I dose-finding and pharmacokinetic study of subcutaneous semisynthetic homoharringtonine (ssHHT) in patients with advanced acute myeloid leukaemia

Abstract

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities and pharmacokinetic of semisynthetic homoharringtonine (ssHHT), given as a twice daily subcutaneous (s.c.) injections for 9 days, in patients with advanced acute leukaemia, 18 patients with advanced acute myeloid leukaemia were included in this sequential Bayesian phase I dose-finding trial. A starting dose of 0.5 mg m(-2) day(-1) was explored with subsequent dose escalations of 1, 3, 5 and 6 mg m(-2) day(-1). Myelosuppression was constant. The MTD was estimated as the dose level of 5 mg m(-2) day(-1) for 9 consecutive days by s.c. route. Dose-limiting toxicities were hyperglycaemia with hyperosmolar coma at 3 mg m(-2), and (i) one anasarque and haematemesis, (ii) one life-threatening pulmonary aspergillosis, (iii) one skin rash and (iv) one scalp pain at dose level of 5 mg m(-2) day(-1). The mean half-life of ssHHT was 11.01+/-3.4 h, the volume of distribution at steady state was 2+/-1.4 l kg(-1) and the plasma clearance was 11.6+/-10.4 l h(-1). Eleven of the 12 patients with circulating leukaemic cells had blood blast clearance, two achieved complete remission and one with blast crisis of CMML returned in chronic phase. The recommended daily dose of ssHHT on the 9-day schedule is 5 mg m(-2) day(-1).

Figure 1

Kaplan–Meier survival curve in treated patients (n=18).

Figure 2

Concentration–time profiles of HHT at dose levels ranging from 0.5 to 5 mg m⁻² day⁻¹ after last injection at day 9. Data from the same dose levels were grouped and are presented as mean values (symbols)±s.e. (error bar). The legend indicates each of the dose levels used.