General Information

**Withdrawn from market in May of 2022 after failing to confirm clinical benefit in a post-marketing trial**

Marqibo (vinCRIStine sulfate LIPOSOME injection) is vincristine encapsulated in sphingomyelin/cholesterol liposomes. The encapsulation formulation was designed to enhance efficacy, with the potential for reduced toxicity. Vincristine is a vinca alkaloid; it is thought to work by interfering with cancer cell growth during mitosis.

Marqibo is specifically indicated for the treatment of adults with Philadelphia chromosome-negative (Ph-) acute lymphoblastic leukemia in second or greater relapse or whose disease has progressed following two or more anti-leukemia therapies.

Marqibo is supplied as a solution for intravenous injection. The recommended initial dose is 2.25 mg/m2 intravenously over one hour once every seven days.

Clinical Results

The FDA accelerated approval of Marqibo was based on an international, open-label, multi-center, single-arm trial. The trial enrolled 65 adults with Philadelphia chromosome negative ALL in second or greater relapse or whose disease progressed after two or greater treatment lines of anti-leukemia therapy. Subjects had to have achieved a complete remission to at least one prior anti-leukemia chemotherapy. The subjects received intravenous Marqibo monotherapy at 2.25 mg/m2 over 60 minutes every seven days. Concomitant corticosteroids were not permitted beyond Day 5. Three subjects (4.6%) achieved complete remission (CR); Seven subjects (10.8%) achieved CR with incomplete blood count recovery (CRi) and ten subjects (15.4%) achieved CR + Cri. The median duration of CR or CRi, based on the first date of CR or CRi to the date of the last available histologic assessment of the same response (n=8) was 28 days. The median duration of CR or CRi, based on the first date of CR or CRi to date of documented relapse, death, or subsequent chemotherapies including hematopoietic stem cell transplant (n=10), was 56 days.

Side Effects

Adverse events associated with the use of Marqibo may include, but are not limited to, the following:

• constipation
• nausea
• pyrexia
• fatigue
• peripheral neuropathy
• febrile neutropenia
• diarrhea
• anemia
• decreased appetite
• insomnia

Mechanism of Action

Marqibo (vinCRIStine sulfate LIPOSOME injection) is vincristine encapsulated in sphingomyelin/cholesterol liposomes. Non-liposomal vincristine sulfate binds to tubulin, altering the tubulin polymerization equilibrium, resulting in altered microtubule structure and function. Non-liposomal vincristine sulfate stabilizes the spindle apparatus, preventing chromosome segregation, triggering metaphase arrest and inhibition of mitosis.