J. Med. Chem. 2009, 52, 6527–6530 6527
DOI: 10.1021/jm9010065
such as breast, ovarian, and bladder tumors, as well as in
squamous cell carcinomasofthe headandneck.3 Heterodimer
signaling is believed to play a significant role in the pathobio-
logy of these tumors. The ability of HER2 to transactivate
other receptors of the HER family by heterodimerization
suggests that simultaneous inhibition of HER1 and HER2
may provide superior efficacy than single receptor targeting
via different and potentially nonoverlapping mechanisms.1 A
high degree of sequence homology (83% identity) between the
two kinase domains supports the feasibility of identifying
compounds that inhibit both receptors with comparable
potency. Lapatinib, an oral dual inhibitor of HER1 and
HER2, was recently approved in combination with capecita-
bine for the treatment of patients with HER2 overexpressing
advanced or metastatic breast cancer.4
We have previously reported the discovery of pyrrolo[2,1-f ]-
[1,2,4]triazine nucleus as a versatile scaffold for ATP-compe-
titive kinase inhibitors.5 Subsequently, we demonstrated that
dual inhibitors of HER1 and HER2 kinases can be prepared
via introduction of a lipophilic 5-amino-1-benzylindazole
substituent at C4 and a carbamate linker at the C6 position
of the pyrrolotriazine.6 The extended aniline motif conferred
improved potency against HER2 while retaining HER1 in-
hibition. As depicted in Table 1, 1 was the initial lead that
exhibited potent inhibition of HER2/HER1 enzymes and
submicromolar potency in antiproliferative assays using
HER2/HER1-dependent cells. Compound 1 did not show
significant activity against HER2/HER1 independent A2780
tumor cells, suggesting thereby that the cellular effects are
specific to inhibition of HER kinases. This paper describes
further optimization of in vitro potency and pharmacokinetic
properties leading up to the identification of 13, a HER1/
HER2 kinase inhibitor that has advanced into clinical devel-
opment.7
Discovery and Preclinical Evaluation of
[4-[[1-(3-fluorophenyl)methyl]-1H-indazol-
5-ylamino]-5-methylpyrrolo[2,1-f][1,2,4]triazin-
6-yl]carbamic Acid, (3S)-3-Morpholinylmethyl
Ester (BMS-599626), a Selective and Orally
Efficacious Inhibitor of Human Epidermal
Growth Factor Receptor 1 and 2 Kinases
Ashvinikumar V. Gavai,*,§ Brian E. Fink,§
David J. Fairfax,‡ Gregory S. Martin,‡ Lana M. Rossiter,‡
Christian L. Holst,‡ Soong-Hoon Kim,§ Kenneth J. Leavitt,§
Harold Mastalerz,§ Wen-Ching Han,§ Derek Norris,§
Bindu Goyal,§ Shankar Swaminathan,§ Bharat Patel,§
Arvind Mathur,§ Dolatrai M. Vyas,§ John S. Tokarski,§
Chiang Yu,§ Simone Oppenheimer,§ Hongjian Zhang,§
Punit Marathe,§ Joseph Fargnoli,§ Francis Y. Lee,§
Tai W. Wong,§ and Gregory D. Vite§
§Bristol-Myers Squibb Research and Development,
P.O. Box 4000, Princeton, New Jersey 08543, and
‡Albany Molecular Research, 21 Corporate Circle,
P.O. Box 15098, Albany, New York 12212
Received July 8, 2009
Abstract: Structure-activity relationships in a series of 4-[1H-
indazol-5-ylamino]pyrrolo[2,1-f][1,2,4]triazine-6-carbamates identi-
fied dual human epidermal growth factor receptor (HER)1/HER2
kinase inhibitors with excellent biochemical potency and kinase
selectivity. On the basis of its favorable pharmacokinetic profile and
robust in vivo activity in HER1 and HER2 driven tumor models, 13
(BMS-599626) was selected as a clinical candidate for treatment of
solid tumors.
Previous studies had established that biochemical potency
could be improved via optimization of the linker group at C6
position.6 In the proposed binding model for the pyrrolotria-
zine nucleus in the ATP binding site of HER1 kinase, the C6
position points toward a specificity pocket that leads to sur-
face exposed protein.6 It was deemed to be an appropriate
position to incorporate a polar functionality, such as an
aliphatic amine, through the C6 carbamate. This change
was predicted to favorably influence physical properties and
the pharmacokinetic profile of the kinase inhibitors. To
evaluate this hypothesis, a variety of cyclic amines were
appended to the pyrrolotriazine using the C6 carbamate
linker. As shown in Table 1, the N-piperidinylethyl and
N-piperazinylethyl analogues 2 and 3 displayed the desired
increase in potency in HER2 overexpressing BT474 and N87
cell proliferation assays. The corresponding morpholine deri-
vative 4 was less potent in the enzymatic assays. It was
expected that sustained inhibition of HER1 and HER2 for a
prolonged period of time would be necessary for robust in
vivo activity in tumor models. To that end, plasma exposures
of lead candidates were investigated in mice for 4 h following
oral administration. The observed low systemic exposures of2
and 3 (Table 1) were attributed to a combination of poor
absorption and insufficient metabolic stability in isolated liver
microsomes.8 It has been suggested that the greater polarity
Receptor tyrosine kinases play a crucial role as signal
transducers in dysregulated cell proliferation, differentiation,
and evasion from apoptosis. Two members of the epidermal
growth factor receptor family, HER1 (EGFR) and HER2
(ErbB2), have been clinically validated as rational targets for
cancer therapy.1 Activation of the HERa receptors via homo-
orheterodimerizationis followed by receptor autophosphory-
lation, recruitment of adaptor proteins, and the activation of
downstream signaling, such as those mediated by Ras/Raf/
MAPK and the PI3K/Akt pathways.2 Overexpression or
constitutiveactivation of HER1 and HER2 has been observed
in many tumor types, including colon, breast, ovarian, head
and neck, and non-small cell lung cancer, and frequently
correlates with poor clinical prognosis.
A number of pharmacologic agents have demonstrated
clinical benefit via modulation of HER1 or HER2 receptor.1
These include HER1-specific antibody cetuximab, HER2-
specific antibody trastuzumab, and small molecule HER1
kinase inhibitors gefitinib and erlotinib. Coexpression of
HER1 and HER2 kinases has been shown in many tumors,
*To whom correspondence should be addressed. Phone: 609-252-
5091. Fax: 609-252-3993. E-mail: ashvinikumar.gavai@bms.com.
a Abbreviations: HER, human epidermal growth factor receptor;
MRT, mean residence time; TGI, tumor growth inhibition.
r
2009 American Chemical Society
Published on Web 10/12/2009
pubs.acs.org/jmc