Imatinib—A New Tyrosine Kinase Inhibitor for First-Line Treatment of Chronic Myeloid Leukemia in 2015

Abstract

A final point concerns the costs of the different therapies: even when other factors are not considered, the cost for using imatinib is going to decrease substantially in 2015, at least in the United States, because of patent expiration. Therefore, the cost of 1 quality-adjusted life-year saved using the different TKIs is going to diverge dramatically in favor of imatinib. This fact will need proper consideration when budget-conscious decisions are made in the future. Generic imatinib has been available since 2013 in Canada and South Korea, at prices between 10% and 25% of the branded version. The availability of generic imatinib will facilitate access to this costly drug in countries such as the United States and will contribute to eliminating the related financial hurdles that were documented in previous multinational studies.⁹ In such a scenario, if generic imatinib will cost between 10% and 30% as much as the branded product and the organization of care for patients with CML is optimized,⁸,9 an amelioration of CML long-term prognosis in the United States can be expected and will be testified by the shrinkage of the differences in CML mortality between Surveillance, Epidemiology, and End Results and other registries such as the Swedish Cancer Registry, which are presently approximately 20%.

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Copyright 2015 American Medical Association. All rights reserved.
Imatinib—A New Tyrosine Kinase Inhibitor
for First-Line Treatment of Chronic
Myeloid Leukemia in 2015
Imatinib mesylate changed the prognosis for chronic
myeloid leukemia (CML) so dramatically that patients
with newly diagnosed CML starting treatment with ima-
tinib now have a normal life expectancy,
1,2
compared
with the historical median survival of 2 to 3 years. In ad-
dition to its outstanding therapeutic activity, imatinib
possesses a remarkably safe profile.
Second- and third-generation tyrosine kinase
inhibitors (TKIs) were developed primarily for second-
and third-line use: bosutinib monohydrate, dasatinib,
nilotinib, and ponatinib hydrochloride constitute a set
of formidable “spare wheels” for patients whose ima-
tinib treatment fails, giving a viable option to more than
50% of them. These drugs contributed to achieving
the observed normal life expectancy in patients with
CML who start first-line imatinib treatment. Dasatinib
and nilotinib also obtained first-line indication and have
been aggressively marketed as a replacement for the
“aging” imatinib.
The supposed superiority of second-generation
TKIs is based on 2 registration studies, the DASISION
and ENESTnd protocols, which showed a faster reduc-
tion of BCR/ABL 1 gene transcripts, a 10% to 15%
increase in the rate of complete cytogenetic responses
(CCRs) by 12 months, and a protection from progres-
sion to accelerated phase–blast crisis (APBC) of 2% to
3.5%. This last effect, however, is not established;
although it was statistically significant in the ENESTnd
study, it was reported as a statistically insignificant
“trend” in the DASISION trial; in fact, a subsequent
independent replica of the DASISION trial failed to
show any difference in progression to APBC between
patients treated with imatinib and nilotinib.
3
Moreover, the way that data were initially col-
lected in ENESTndraises doubts that some patients could
have discontinued participation in the study for rea-
sons different from those reported.
4
Because the dif-
ference in progression to APBC between the 2 groups
of patients is small, even a few cases can make a sub-
stantial impact on the final results. In fact, a recent up-
date of the ENESTndstudy, presented at the 2014Ameri-
can Society of Hematology meeting, showed that the
difference in progression to APBC between the ima-
tinib and the nilotinib 300 mg twice daily treatment
groups lost its statistical significance.
5
Finally, a recent
replica of ENESTnd (ENESTChina) in 267 Chinese pa-
tients did not show any significant difference between
patients with newly diagnosed CML receiving imatinib
or nilotinib in overall survival, progression-free sur-
vival, progression to APBC (1.5% in each arm), and
6-month (66% vs 57%) and 12-month(77% vs 77%) CCR
rates; the only significant difference observed was in the
rate of major molecular response at 12 months.
6
It has to be remembered that it has always been
difficult to discern an independent prognostic value for
molecular responses outside of cytogenetic ones.
7
If
obtaining “faster and deeper” responses using second-
generation TKIs does not convert into a better progno-
sis, then this phenomenon should not dictate a change
in therapy by itself.
Whereas the superiority of second-generation TKIs
over imatinib in terms of first-line therapeutic activity
seems questionable, the safety profiles of these drugs
are also a matter of debate. Dasatinib’s safety profile
includes pleural and pericardial effusion in a sizeable
proportion of patients, especially after long-term use.
Nilotinib is even more dangerous: the drug causes a sort
of “metabolic syndrome” characterized by increased
glucose, cholesterol, and triglyceride levels, which lead
to clinical diabetes mellitus in up to 18% of patients and
to accelerated atherosclerosis and arterial thrombosis
including peripheral arterial occlusive disease in a yet-
unspecified proportion of patients, which can be
gauged to be between 5% and 25% after 5 years of
treatment.
8
Imatinib, in contrast, shows a remarkably safe tox-
icity profile, even in long-term studies
9
; however, its ad-
verse effects are felt by patients and can diminish their
quality of life, decrease adherence, and cause treat-
ment failures and must therefore be tackled by treating
physicians. In this respect, the logistical organization of
care plays a fundamental role in the final outcome, as wit-
nessed by wide variations in response rates in different
logistical settings. The rates of CCR after 12 months of
imatinib therapy can span from values close to 90%
1
down to 40% and even 18%.
8
A recent analysis per-
formed in the US community setting of the types of lo-
gistical and geographical CML management, and ef-
fects on patients’ survival,
10
supports this conclusion.
A final point concerns the costs of the different
therapies: even when other factors are not considered,
the cost for using imatinib is going to decrease substan-
tially in 2015, at leastin the United State s, because of pat-
ent expiration. Therefore, the cost of 1 quality-adjusted
life-year saved using the different TKIs is going to di-
verge dramatically in favorof imatinib. This fact will need
proper consideration when budget-conscious deci-
sions are made in the future. Generic imatinib has been
available since 2013 in Canada and South Korea,at prices
between 10% and 25% of the branded version. Theavail-
ability of generic imatinib will facilitate access to this
costly drug in countries such as the United States and
VIEWPOINT
Carlo Gambacorti-
Passerini, MD
Department of Health
Sciences, University of
Milano-Bicocca, Monza,
Italy; and Section of
Hematology, San
Gerardo Hospital,
Monza, Italy.
Rocco Piazza, MD,
PhD
Department of Health
Sciences, University of
Milano-Bicocca, Monza,
Italy.
Corresponding
Author: Carlo
Gambacorti-Passerini,
MD, Department of
Health Sciences,
University of
Milano-Bicocca,
Via Cadore 48,
20900 Monza, Italy
(carlo.gambacorti
@unimib.it).
Opinion
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Copyright 2015 American Medical Association. All rights reserved.
will contribute to eliminating the related financial hurdles that were
documented in previous multinational studies.
9
In such a scenario,
if generic imatinib will cost between 10% and 30% as much as the
branded product and the organization of care for patients with CML
is optimized,
8,9
an amelioration of CML long-term prognosis in the
United States can be expected and will be testified by the shrink-
age of the differences in CML mortality between Surveillance, Epi-
demiology, and End Results and other registries such as the Swed-
ish Cancer Registry, which are presently approximately 20%.
Thus, what is “aging” here is only the lifespan of the imatinib pat-
ent; imatinib is well, and its generic form represents the true “new”
TKI for 2015. Rigorous quality control on the activity and safety of
generic imatinib and a sufficiently high number of producers (>5) will
be vital to ensure confidence in its use.
ARTICLE INFORMATION
Published Online: March 12, 2015.
doi:10.1001/jamaoncol.2015.50.
Conflict of Interest Disclosures: Dr Gambacorti-
Passerini has received research grants from Pfizer
and serves on the advisory boards of Pfizer and
Bristol-Myers Squibb. No other disclosures are
reported.
Funding/Support: This study was supported by the
Associazione Italiana per la Ricerca sul Cancro (AIRC
2013 IG-14249 to Dr Gambacorti-Passerini).
Role of the Funder/Sponsor:The funder had no
role in the collection, management, analysis, and
interpretation of the data; preparation, review, or
approval of the manuscript; and decision to submit
the manuscript for publication.
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