Inotuzumab Ozogamicin (Besponsa) Therapy Helps People with Relapsed or Refractory B-Cell ALL Reach MRD Negativity

Posted on: Aug 17, 2026

A recent study found that inotuzumab ozogamicin (InO) helped patients with acute lymphoblastic leukemia (ALL) reach minimal residual disease (MRD) negativity. The patients had relapsed or refractory B-cell ALL that was in remission but still had some remaining cancer cells.

InO, also known as Besponsa (Pfizer), is an FDA-approved antibody drug conjugate (ADC) used to treat relapsed or refractory B-cell ALL in adults. ADCs work by delivering chemotherapy directly to cancer cells. InO was approved for use in people with ALL in 2017. This research looked at previously treated B-cell ALL that was in complete remission with positive MRD.

Increased rates of MRD negativity among patients

When InO was approved in 2017, research showed that it improved complete response among patients. Complete response is a standard measurement of cancer remaining after treatment.

This recent study looked closely at the impact of InO on MRD. MRD testing uses newer technology to measure remaining cancer cells. Because the test is so sensitive, it helps predict patient outcomes. Reaching MRD negativity after induction or consolidation therapy is associated with a lower risk of relapse and better survival outcomes.

The participants in this study had relapsed or refractory B-cell ALL that was in complete remission but MRD positive. This means highly sensitive tests found small amounts of cancer cells. The patients were given up to 6 cycles of InO.

Researchers found that the treatment led to deep responses for many participants. Overall, 70% of patients achieved MRD negativity. Every patient with Ph-negative acute lymphoblastic ALL reached MRD negativity. For those with Ph-positive ALL, 65% reached MRD negativity. Using next-generation sequencing, an even more sensitive testing method, researchers reported an MRD negativity rate of 73%.

Patients were followed for a median of 50 months. The median overall survival was 61 months, and the median relapse-free survival was 40 months.

Results were better among people who had InO earlier

The timing of treatment also appeared to make a difference. Patients who received the therapy during their first remission had particularly strong outcomes. At the time of the analysis, the median overall survival for these patients had not yet been reached. This means more than half were still alive. In comparison, patients who received the treatment during their second remission or later had a median overall survival of 14 months.

What were the side effects of InO?

The treatment was generally well tolerated. Three patients (8%) developed nonfatal sinusoidal obstructive syndrome. This is a liver complication that can occur after stem cell transplantation. Researchers concluded that the treatment had an acceptable safety profile.

InO helps patients achieve deep remission

These findings suggest that this treatment may help many people with ALL achieve deep remission, especially when it is used earlier in the course of treatment. This was true even for patients who had already been treated with blinatumomab (Blincyto), another medication that is used to achieve MRD negativity. This means that InO provides an alternative for patients who are relapsed/refractory to blinatumomab.

The high MRD negativity rates and encouraging long-term survival results support further research into this approach and can help guide future treatment decisions.

Understanding the impact of MRD negativity on overall outcomes will help in decision-making about the best treatment path after diagnosis.

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