Purpose: Pegylated liposomal doxorubicin (PLD) is often used in elderly people, due to its improved tolerability. However, clinical and pharmacological data in the subset of patients over 70 are scanty.
Methods: PLD safety was evaluated in 35 patients (aged ≥70 years) who were treated with PLD as a single agent for 165 cycles. Doxorubicin plasma levels, leukocyte DNA breaks and monocyte count variations were measured as markers of drug exposure, DNA repair capability and reticuloendothelial system activation, respectively. A correlation between these markers and age was sought.
Results: Treatment was generally well tolerated. Skin erythrodysesthesia was the most frequent side effect, and no severe (G4) toxicity occurred. PLD plasma half-life generally correlated with age (P < 0.001) and was particularly prolonged in octogenarians (P = 0.005). Doxorubicin clearance significantly declined up to 70 % at cycle 7. DNA breaks increased over the first two cycles (P = 0.007) and were inversely correlated with age (P = 0.007) and directly with clearance (P = 0.006). Pre-treatment monocyte counts increased over cycles (P < 0.001) and were associated with an increase in clearance at cycle 3 (P = 0.015). The hand-foot-skin syndrome was significantly more severe in patients of advanced age or longer PLD half-life.
Conclusions: This study showed (1) increased systemic drug exposure over subsequent cycles; (2) association of age with increased drug exposure, reduced DNA repair capability and worse skin toxicity; (3) a relation between monocyte count and drug clearance.