s been reported in both male and female post-pubertal patients who received multi-agent chemotherapy including non-liposomal vincristine sulfate. The degree to which testicular or ovarian functions are affected is age-, dose-, and agent-dependent. Recovery may occur in some but not all patients.
Animal Toxicology and/or Pharmacology
In a repeat-dose comparative toxicology study in rats, vincristine sulfate liposome injection or non-liposomal vincristine sulfate was administered to animals intravenously once per week for 6 weeks. Clinical signs of toxicity consistent with neurotoxicity were greater with vincristine sulfate liposome injection than with non-liposomal vincristine sulfate at equal vincristine sulfate doses of 2 mg/m2/week and included uncoordinated movements, weakness, reduced muscle tone, and limited usage of the limbs. Neurological testing indicated drug-induced peripheral neurotoxicity with both drugs. Based on the histopathology examination after 6 weekly doses, vincristine sulfate liposome injection induced greater peripheral neurotoxicity (nerve fiber degeneration) and secondary skeletal muscle atrophy than the equal dose of non-liposomal vincristine sulfate. In a separate tissue distribution study in rats, administration of 2 mg/m2 of intravenous liposomal or non-liposomal vincristine sulfate showed greater accumulation of vincristine sulfate in sciatic and tibial nerves (as well as the lymph nodes, spleen, and bone marrow) of the animals following vincristine sulfate liposome injection.
Clinical Studies
Acute Lymphoblastic Leukemia
Marqibo was studied in an international, open-label, multi-center, single-arm trial (Study 1). Eligible patients were 18 years of age or older with Philadelphia chromosome negative ALL in second or greater relapse or whose disease progressed after two or greater treatment lines of anti-leukemia therapy. Patients had to have achieved a complete remission (CR) to at least one prior anti-leukemia chemotherapy, defined by a leukemia-free interval of equal or more than 90 days. Patients were not eligible for immediate hematopoietic stem cell transplantation (HSCT) at the time of screening and enrollment.
Patients received intravenous Marqibo monotherapy at 2.25 mg/m2 over 60 minutes every 7 days. Concomitant corticosteroids were not permitted beyond Day 5.
The treated population included 65 patients who received at least 1 dose of Marqibo. All of the treated patients had received prior vincristine sulfate and 80% had evidence of residual neuropathy at study baseline. Among treated patients, 51% were male, 86% were white, 45% were under 30 years of age, 11% were age 65 or older, 48% had undergone prior HSCT, 51% had received 3 or more prior therapies, and 45% were refractory to their immediate prior therapy. Disease characteristics were 85% precursor B-cell ALL and 15% precursor T-cell ALL. In addition, 22 of 65 (34%) treated patients did not receive asparaginase products prior to enrollment. Efficacy results are shown in Table 4.
Table 4. Study 1 Results Study 1
(N=65)
n (%)
*
CI = Confidence interval (Clopper-Pearson).
Complete remission (CR) 3 (4.6)
CR with incomplete blood count recovery (CRi) 7 (10.8)
CR + CRi 10 (15.4)
(95% CI*) (7.6 – 26.5)
MEDIAN DURATION of CR or CRi: Days (95% CI)
Based on the first date of CR or CRi to the date of the last available histologic assessment of the same response (n=8) 28 (7, 3
