Product Information

Registration Status: Active

BESPONSA POWDER FOR CONCENTRATE FOR SOLUTION FOR INFUSION 1MG/VIAL is approved to be sold in Singapore with effective from 2019-07-17. It is marketed by PFIZER PTE LTD, with the registration number of SIN15747P.

This product contains Inotuzumab Ozogamicin 1mg/vial in the form of POWDER, FOR SOLUTION. It is approved for INTRAVENOUS use.

This product is manufactured by Wyeth Pharmaceutical Division of Wyeth Holding LLC in UNITED STATES.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Inotuzumab Ozogamicin


Inotuzumab ozogamicin is an antibody-drug conjugate using linker and cytotoxic drug technology similar to that developed for the ground-breaking treatment Mylotarg ([DB00056]), which was approved by the US FDA in 2000 for the treatment of acute myeloid leukaemia. Inotuzumab ozogamicin consists of a recombinant humanised IgG4 kappa CD22-targeting monoclonal antibody covalently attached to calicheamicin derivative, N-acetyl-gamma-calicheamicin dimethylhydrazide, which is a potent DNA-binding cytotoxic agent [A20352]. Developed by Pfizer and UCB, inotuzumab ozogamicin was granted approval by EU in June 2017 followed by FDA on August 17th, 2017 for the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). ALL is a rapidly progressing cancer of the bone marrow that is associated with high mortality rates and low therapeutic response from standard chemotherapies in relasping conditions. In a randomized trial, inotuzumab ozogamicin displayed higher percentages of patients undergoing longer periods of complete remission with no evidence of disease in comparison to patients receiving alternative chemotherapy [A20353].


Indicated as monotherapy for the treatment of adults with relapsed or refractory CD22-positive B cell precursor acute lymphoblastic leukaemia (ALL).

Mechanism of Action

Inotuzumab ozogamicin is comprised of cytotoxic antibiotic N-acetyl-gamma-calicheamicin dimethylhydrazide attached to a humanized monoclonal IgG4 antibody via 4-(4 acetylphenoxy) butanoic acid (acetyl butyrate) linker. The drug exerts a potent cytotoxic effect against CD22+ B-cell lymphoma when the antibody binds to the CD22 receptor on the surface of B cells . The drug-CD22 complex is rapidly internalized into the cell, forming an endosome which subsequently fuses with lysosomes. N-acetyl-gamma-calicheamicin dimethylhydrazide is then intracellularly released into the acidic environment. N-acetyl-gamma-calicheamicin dimethylhydrazide is a calicheamicin derivative, which is naturally produced by the bacterium Micromonospora echinospora, and is toxic to the body when not bound to the antibody. It mediates apoptosis of the cell by binding to the minor groove of DNA in a sequence-specific manner and undergoing a structural change to generate diradicals [A20354]. These changes abstract hydrogen ions from the phosphodiester bonds of double-stranded DNA, resulting in breaks and cell apoptosis [A3883, A3884, A20352].


Inotuzumab ozogamicin is intended to be administered in cycles that each run for 3 to 4 weeks. The steady state exposure of the drug is reached by Cycle 4. The mean (SD) maximum serum concentration (Cmax) of inotuzumab ozogamicin was 308 ng/mL (362) with patients receving the recommended dose of 1.8 mg/m^2/cycle [L938].
The total volume of distribution of inotuzumab ozogamicin is approximately 12L [L938].
N-acetyl-gamma-calicheamicin dimethylhydrazide primarily undergoes nonenzymatic reduction *in vitro*. The metabolism of N-acetyl-gamma-calicheamicin dimethylhydrazide in human serum is not clearly understood as the level of the drug is below the limit of quantification of 50 pg/mL [L938]. The antibody portion of the drug is thought to undergo proteolytic degradation into amino acids then recycled into other proteins [A20351].


The clearance of inotuzumab ozogamicin at steady state is 0.0333 L/h [L938].


Inotuzumab ozogamicin was shown to be clastogenic *in vivo* in the bone marrow of male mice but was not mutagenic in an* in vitro* bacterial reverse mutation (Ames) assay. In rat toxicity studies, rats developed oval cell hyperplasia, altered hepatocellular foci, and hepatocellular adenomas however the carcinogenic potential of inotuzumab ozogamicin on humans is undetermined. Based on reproductive toxicity studies involving female rats and non-clinical studies, inotuzumab ozogamicin has the potential to impair reproductive function and fertility in men and women [L938].

Active Ingredient/Synonyms

Inotuzumab ozogamicin | Inotuzumab ozogamicin |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank