“In a large cohort of patients with APL, the chemo-free combination of ATRA/ATO is confirmed as the best treatment option, prolonging overall and event-free survival and reducing the relapse rate compared with ATRA/chemotherapy,” said first author Maria Teresa Voso, MD, of Tor Vergata University, in Rome, in presenting the findings at the 2023 annual meeting of the European Hematology Association.
APL, though rare, makes up about 10% of new AML cases, and the advent of the chemo-free ATRA-ATO regimen in recent years has transformed the disease, significantly improving survival.
However, with ongoing questions regarding factors associated with treatment benefits based on issues including the level of risk, Dr. Voso and colleagues turned to data from the large European Union–funded HARMONY registry, a big data project that uniquely provides real-world as well as clinical trial findings from diverse APL patient populations.
They identified 937 patients in the registry with newly diagnosed APL between 2007 and 2020 who met the study’s data quality criteria, including 536 (57.2%) patients from two clinical trials, the UK AML-17 and GIMEMA APL0406 trials, and 401 (42.8%) patients from national registries in 6 countries, representing real-world data.
The median duration of follow-up was 5.66 years, with a range of 0-14 years.
The patients had an average age of about 50, which is consistent with the lower age of diagnosis typical of APL, compared with other forms of AML.
Among them, 380 (40.6%) were treated with the ATRA-ATO regimen while 509 (54.3%) received the chemotherapy combination of ATRA-Idarubicin (AIDA).
Overall, 37.8% were determined to be low risk, as assessed by the Sanz risk-score; 42.3% were intermediate risk, and 18.7% were considered high risk. The rate of complete remission among the patients was 87.5%, and 9% had relapsed.
The results showed the 10-year overall survival (OS) rate to be 92% among the chemo-free ATRA-ATO-treated patients versus 75% in the AIDA-treated patients (P = .001).
Likewise, those treated with the chemo-free regimen had a higher event-free survival and a lower cumulative incidence of relapse (CIR) versus chemotherapy over 10 years (P < .001 for both).
In further stratifying by risk, patients who were low risk also had greater improvements with the chemo-free regimen in overall survival (P = .004), event-free survival, and CIR versus AIDA treatment (P < .001).
Among high-risk patients, however, only event-free survival was significantly improved in the chemo-free treated patients (P = .046).
Older age stood out as a significant determinant of survival, with patients in the age 50-69 and 70 or over age groups having a significantly lower rate of overall survival and event-free survival, compared with those under 50 years of age (P < .001), with those risks observed regardless of treatment type.
Age was not a significant factor in terms of the incidence of relapse (P = .159).