Pfizer’s ADC ambition bolstered by US Besponsa approval
Besponsa (inotuzumab ozogamicin), indicated for the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia, was granted approval from the US Food and Drug Administration (FDA) under its breakthrough therapy designation and priority review programme.
“Besponsa will help address a significant need for new treatment options in B-cell acute lymphoblastic leukemia, and may help more patients reach stem cell transplant, which provides the best chance for long term remission,” said president of Pfizer Oncology, Liz Barrett.
Besponsa
Besponsa is an ADC comprised of a monoclonal antibody (mAb) targeting CD22, a cell surface antigen expressed on cancer cells, linked to a cytotoxic agent.
Besponsa binds to the CD22 antigen on B-cells, it is internalised into the cell, where the cytotoxic agent calicheamicin is released causing cell death.
The drug is administered intravenously via hour-long infusions.
The US labelling for the drug includes a warning for hepatotoxicity, including hepatic veno-occlusive disease (VOD), and increased risk of post-HSCT (hematopoietic stem cell transplantation) non-relapse mortality.
Pfizer spokesperson Dervila Keane told Biopharma-Reporter Besponsa is manufactured at Pfizer’s Pearl River, NY, US-based facility, where the firm also makes its acute myeloid leukemia (AML) ADC Mylotarg.
Mylotarg was the first ADC launched in the US, following FDA approval in May, 2000. The firm voluntarily withdrew the drug in 2010, after results from a post-approval clinical trial raised concerns about its safety and efficacy.
Earlier this year, Pfizer resubmitted a biologics license application (BLA) for Mylotarg. On June 11, the firm announced the FDA’s Oncologic Drug Advisory Committee (ODAC) voted that clinical results demonstrated a favourable risk:benefit profile for Mylotarg.
The firm expects a decision by the FDA next month.
More ADCs for Pfizer?
While Keane did not provide specific details on future ADC-related projects for Pfizer, she told us the firm is exploring a number of antibody-linker-cytotoxin options.
“Pfizer is using its understanding of the biology of cancer to explore a number of antibody-linker-cytotoxin combinations and build proprietary ADC platforms using a diverse array of ADC design components.”
Pricing
Pfizer spokesperson Dervila Keane told Biopharma-Reporter the cost of Besponsa will vary in individual countries.
“However, it is Pfizer’s priority to make Besponsa broadly accessible and available to patients with relapsed/refractory acute lymphoblastic leukemia,” she said.
“In setting a price for any new medicine, we work with a broad array of experts and with payers and governments around the world to negotiate a price that reflects the value of the medicine relative to the unmet need it addresses, other innovative alternative treatments and considering affordability in the context of the local market,” said Keane.
