Decitabine Super-Responders: Challenging the Dogma of Long-Term Remission for Acute Myeloid Leukemia
Authors: Maakaron Joseph , Mannis Gabriel N. , Walker Alison R. , Mims Alice S. 
Published: October 2019

Abstract
Introduction
Decitabine and hypomethylating agents are considered non-curative treatments for patients with acute myeloid leukemia (AML) and are a standard approach for those patients not fit for intensive induction chemotherapy, usually due to age and multiple comorbidities. A phase 2 study reported a better overall response rate of 64% with a 10-day schedule of decitabine (Blum, Garzon et al. 2010). A second study reported on a higher rate of response among patients with TP53 mutations (Welch, Petti et al. 2016). However, these responses were not considered durable with median duration of response of about 11 months. We herein describe four patients with longer than expected response duration to decitabine, two of which were able to discontinue therapy with sustained multi-year remission and an apparent cure of their AML.
Methods
We sought to evaluate the clinical and pathological characteristics of patients with a particular long-term response to decitabine. We screened patients at two institutions who have been in complete remission (CR) for greater than 2 years with single-agent decitabine therapy. Current efforts are on-going to identify patients from five other institutions that also meet these criteria and will be added for the final presentation of this data.
Results
Four patients have been identified who have experienced CR for over 2 years with average age at diagnosis of 70 years (range 60-76). Three patients had cytogenetically normal (CN) AML and one had core-binding factor (CBF) with t(8;21). Time to treatment response for CR was as follows: 2 patients required 2 cycles, 1 required 1 cycle, and 1 required 4 cycles of decitabine. Two CN patients received 27 cycles of decitabine in total before therapy discontinuation because of trial termination [1]. One patient has remained in CR for 4 years while the second CR lasted for 8 years after cessation of therapy. Both patients were lost to follow-up after those time periods. The other CN patient remains in CR and continues on therapy (30 cycles). The CBF patient relapsed after 28 cycles of therapy and unfortunately succumbed to complications of relapsed AML. Molecular testing was performed on 2 of 4 patients as listed in Table 1 with no clear correlation to outcomes with this limited number of patients.
Discussion
Currently, the only acceptable long-term cure for patients with AML is intensive induction followed by consolidation with high-dose chemotherapy or allogeneic stem cell transplant. Elderly patients and patients with multiple comorbid conditions are not candidates for this aggressive approach. Here we present 4 patients with prolonged responses to 10-day decitabine induction therapy with 2 patients who appear to be cured of their AML with this approach. Further study is warranted to better characterize these super-responders and determine if there is a particular subpopulation of patients with AML that can achieve long-term survival without the perils of intensive chemotherapy or stem-cell transplantation.

Disclosures
Mannis: NKarta: Membership on an entity's Board of Directors or advisory committees; Agios: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees. Mims:Abbvie Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees.