How does inotuzumab ozogamicin influence time to first subsequent salvage therapy in patients with relapsed or refractory acute lymphoblastic leukemia?

This study analyzed the effect of inotuzumab ozogamicin (InO; Besponsa) treatment on time to subsequent salvage therapy (TST) in patients with relapsed or refractory acute lymphoblastic leukemia (R/R ALL). The data showed that TST was longer with InO compared to standard of care (SoC) treatment.

Salvage therapy (ST) is treatment given if primary therapy is ineffective, or for patients with intolerance. However, patient outcomes become poorer with successive salvage therapies. Patients may also be at an increased risk of toxicities. TST is a clinical measurement used to determine the duration of clinical benefit. It is the time from first-line treatment to the beginning of the first ST. 

R/R ALL is a rapidly progressive cancer that causes excessive production of white blood cells called lymphocytes. InO is a targeted cancer medication that binds to a protein on the surface of cancerous cells called CD22. It has been shown to improve the outcomes of patients with R/R ALL. However, whether InO also improves the TST compared to SoC treatments in these patients is still unknown.

This study involved 326 patients with CD22+ R/R ALL. Patients were randomly assigned to receive either InO treatment (164 patients) or SoC treatment (162 patients). TST and the proportion of patients that received subsequent therapies were evaluated.

Fewer patients treated with InO needed subsequent ST (34.1%) compared to those who received SoC (56.8%). The average duration of TST was significantly longer for patients who receive InO therapy (18.8 months) compared to those in the SoC group (3.9 months). 

The study concluded that ST was less likely to be needed and TST was significantly longer for patients with R/R ALL that received InO compared to those given SoC.

This study was funded by Pfizer, the manufacturer of InO. The trial was not intended for TST evaluation. Many patients included in the initial trial were lost during follow-up. This might influence the results.