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Single
Agent Arsenic trioxide in the treatment of newly diagnosed acute
promyelocytic leukemia
Arsenic
trioxide (ATO), as a single agent, has proven efficacy in inducing
molecular remission in patients with relapsed and newly diagnosed acute
promyelocytic leukemia (APL). Single
agent ATO based regimen is significantly less expensive than conventional
ATRA based chemotherapy, in the developing world where the cost of
procuring and manufacturing clinical grade ATO is low
1
. However, there
is limited long term data with single agent ATO in the
management of newly diagnosed cases of APL and an optimal schedule has not
been described. We reported our experience with a single agent ATO regimen,
in the management of 72 newly diagnosed cases of APL. Between January 1998
to December 2004, 72 newly diagnosed cases of APL were treated with a
regimen of single agent As2O3. This was an open, non
randomized single center study. The patients were monitored for
hematological and molecular remission and the toxicity profile was
documented. Prognostic factors at diagnosis that influence the event free
survival (EFS) were analyzed. Of
the 72 patients enrolled in the study, there were 7 early deaths secondary
to intra-cranial bleeds, 3 additional patients died prior to achieving a
hematological remission (CR). The CR rate was 86.1%. Molecular remission
was achieved in all evaluable patients. At a
median follow up of 25 months, the 3 year Kaplan-Meier estimate of EFS,
DFS and OS was 74.87±5.6%, 90.17±4.67% and 86.11±4.08% respectively.
Patients presenting with a WBC count <5000 / mm3 and a
Platelet count >20,000 / mm3 at diagnosis {n=22 (30.5%)}
have an excellent prognosis with this regimen (EFS, OS and DFS of 100%).
The toxicity profile in the majority was mild (grade 1 / 2) and reversible.
Two patients had to be withdrawn from the study due to persistent toxicity.
An important aspect that contributed to the low cost of this regimen was
that in the majority post remission induction was administered on an out
patient basis. Some
of the important conclusions of this study were that single agent ATO
based regimen can potentially cure a subset of patients with newly
diagnosed APL, it was well tolerated in the majority and in the developing
world it is an alternative significantly less expensive option of treating
patients with APL. While single agent ATO is unlikely to become the
standard of care in the developed world, this study raises the potential
for considering addition of this extremely effective agent to current
conventional ATRA based regimens to further improve the outcomes in this
disease. Bibliuographical reference:
Vikram Mathews Department of Haematology, Christian Medical College, Vellore, India
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