The FDA has started its priority review of Pfizer’s inotuzumab ozogamicin as a second-line therapy for acute lymphoblastic leukaemia (ALL), setting up a possible approval within six months.
The antibody drug conjugate (ADC) targets CD22-positive cells and delivers the toxic compound calicheamicin into the interior of cells. The drug is designed to kill tumour cells with minimal effects on healthy tissues, and was given breakthrough status by the FDA for ALL in 2015.
The filing is based on the results of the phase III INO-VATE ALL trial involving 326 patients with relapsed or refractory ALL, which showed that inotuzumab outperformed current standards of care. The rate of complete remission was significantly higher in the inotuzumab ozogamicin group than in a group treated with standard chemotherapy – 81% versus 29%, respectively.
The FDA is scheduled to deliver a verdict on Pfizer’s application in August, and Pfizer submitted inotuzumab ozogamicin for approval in the EU last June. The drug has orphan status in both regions.
ALL is one of the four main types of leukaemia and a particularly aggressive form, with a poor prognosis among adults. The main available treatment is long-term chemotherapy, and there is a need for targeted therapies that can improve outcomes.
“ALL that has recurred after, or is refractory to, first-line therapy is a rapidly progressing and deadly disease,” said Mace Rothenberg, chief development officer for oncology at Pfizer. “Based on the positive results of the INO-VATE phase III trial, we believe inotuzumab ozogamicin, if approved, represents a new treatment option for adult patients with relapsed or refractory B-cell precursor ALL.”
Pfizer was also developing inotuzumab ozogamicin for relapsed or refractory aggressive non-Hodgkin’s lymphoma but abandoned that programme after the drug failed to improve survival in a phase III trial. An in-house programme to develop the drug for diffuse large B cell lymphoma (DLBCL) also seems to have been dropped.
The truncated list of potential indications means that sales forecasts for the new drug are modest, with analysts at Credit Suisse suggesting inotuzumab ozogamicin will bring in around $250m in 2020 if approved in the US and EU.