EHA 2026 | Final analysis of the APOLLO trial: ATRA-ATO versus AIDA in high-risk acute promyelocytic leukemia

The Apollo trial was designed for high-risk acute promyelocytic leukemia, including patients with white blood cell counts equal to or over 10,000. And it was designed to compare the classical AIDA regimen to an almost chemo-free regimen, including arsenic trioxide and also all-trans retinoic acid combined during induction with two idarubicin doses and followed by four consolidation cycles with no maintenance as opposed to the AIDA regimen which includes two years of maintenance treatment. And the results have been published last year in the Journal of Clinical Oncology, and the trial met its primary endpoint, which is significantly superior event-free survival of patients treated in the experimental arm, with fewer hematological side effects and also similar rates of differentiation syndrome and early deaths. 

Now at the EHA 2026 we are presenting the updated follow-up, which is now 50 months, median follow-up, and the data confirmed superiority of the experimental arm over standard AIDA, and we are now by over 85% event-free survival for patients treated with ATRA-ATO, similar overall survival, and a significantly inferior probability of relapse, with only one relapse in the experimental arm and 13 relapses in the AIDA arm. We also looked at some additional analysis for EHA, and also, for instance, we evaluated the efficiency of cytoreduction by the two idarubicin doses in the ATRA-ATO arm, and we were able to show that hydroxyurea, which is used conventionally as cytoreduction during induction, is given at similar doses and duration in the experimental versus standard arm. So ATRA-ATO is very efficient in reducing white blood cell counts and this is also the reason why we don’t have more differentiation syndrome despite the fact that we are looking at high-risk APL. And also, of course, the time in the hospital for the patients was reduced, significantly inferior for ATRA-ATO, where we only admit patients during induction and not during consolidation, while for the chemotherapy arm we need several cycles of admission, of hospital admission, during the consolidation phase. And so, you know, we may say that ATRA-ATO is now the standard of care also for high-risk APL and it is being adopted throughout Europe, also accepted, you know, according to several regulations or regulatory agencies are accepting it as a standard of care and this is of course very important for the patients since we also have parallel quality of life analysis which are being presented at EHA this year which show also a significant improved quality of life for patients treated with ATRA-ATO versus chemotherapy.

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