Relapsed ALL: Examining factors that can affect treatment outcomes

This study examined factors important for prognosis in relapsed adult acute lymphoblastic leukemia (ALL). The authors identified a number of factors that can affect the chances of responding to salvage treatment. Authors advised that clinical outcomes for relapsed ALL may be improved with earlier relapse detection and treatment, stem cell transplantation performance, and novel therapies.

Treatment outcomes for ALL have improved in recent years. Complete remission rates after first-line treatment are now between 85 and 90%. However, it has been estimated that at least one-third of intermediate-risk patients and up to two-thirds of high-risk patients eventually experience a relapse. Remission rates after secondary treatment are believed to range from 31 to 44%. This is even lower for patients who have developed a treatment resistance over time. This means they no longer respond to standard therapy and can be difficult to treat. Identifying predictors of long-term prognoses for relapsed ALL is important to help improve clinical outcomes.

The aim of this study was to examine factors that affect treatment outcomes in patients with relapsed ALL.

The records of 547 ALL patients were analyzed. All patients had experienced their first relapse. The average time to relapse was 162 days. 79% of patients had an early relapse (before 18 months) and 21% had a late relapse (after 18 months). 69% of patients relapsed during or after first-line chemotherapy. The remaining 31% relapsed after stem cell transplantation (process in which healthy stem cells are reintroduced to the bone marrow of patients) following complete remission. All patients then underwent secondary (salvage) treatment (mostly with additional chemotherapy).

The time to relapse was significantly shorter in patients who relapsed after a stem cell transplant (average 122 days) compared with those who relapsed during or after chemotherapy (average 288 days). Late relapse was also less common (3%) compared with chemotherapy (29%).

The overall complete remission rate after first salvage treatment was 42%. It was 36% for early relapse and 58% for late relapse. The complete remission rate after first salvage was 46% for patients with B-precursor ALL (most common type in adults). It was 34% for T-precursor ALL patients (more likely to affect young adults and is more common in men). For relapse after a stem cell transplant, the complete remission rate after first salvage treatment was 23%.

Remission rates after first salvage were influenced by age. They decreased from 53% for patients aged 25 years or younger to 37% for patients older than 25. Complete remission was also more likely for late relapse compared to early relapse.

Overall survival (time from treatment until death from any cause) after relapse was 8.4 months. 3-year overall survival was 24%. Predictors of survival included duration of first remission, where the cancer had relapsed, response to salvage treatment, stem cell transplant success, and age. Responding to first salvage treatment increased survival at 3 years 3.2-fold.

The authors reported on a number of factors that can affect the chances of responding to salvage treatment in patients with relapsed ALL. These included age, timing of relapse, and previous treatments received. Response to first salvage therapy is likely the most important predictor of survival. Authors also advised that clinical outcomes for relapsed ALL may be improved with earlier relapse detection and treatment, stem cell transplantation performance, and novel therapies.