Factor VIIa inhibitors

Details Factor VIIa inhibitors Factor VIIa inhibitors

2000-06-07

2002-12-31

Low, Christopher S. F. (Department: 1653)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Peptide containing doai

C530S331000, C514S018700, C562S445000

Reexamination Certificate

active

06500803

ABSTRACT:

The present invention relates to compounds of formula I,
in which R
1
, R
2
, R
91
, R
92
, R
93
, R
94
, R
95
, R
96
, R
97
, r, s, and t have the meanings indicated below. Compounds of formula I are valuable pharmacologically active compounds. They exhibit a strong antithrombotic effect and are suitable, for example, for the therapy and prophylaxis of thromboembolic diseases or restenoses. They are reversible inhibitors of the blood clotting enzyme factor VIIa and can in general be applied in conditions in which an undesired activity of factor VIIa is present or for the cure or prevention of conditions in which an inhibition of factor VIIa is intended. The invention further relates to processes for the preparation of compounds of formula I, their use, in particular as active ingredients in pharmaceuticals, and pharmaceutical preparations comprising them.
The ability to form blood clots is vital to survival. The formation of a blood clot or a thrombus is normally the result of tissue injury that initiates the coagulation cascade and has the effect of slowing or preventing blood flow in wound healing. Other factors that are not directly related to tissue injury like atherosclerosis and inflammation may also initiate the coagulation cascade. In general, a relationship exists between inflammation and the coagulation cascade. Inflammation mediators regulate the coagulation cascade and coagulation components influence the production and activity of inflammation mediators. However, in certain disease states the formation of blood clots within the circulatory system reaches an undesirable level and is itself the source of morbidity potentially leading to pathological consequences. It is nevertheless not desirable in such disease states to completely inhibit the blood clotting system because life threatening hemorrhage would ensue. In the treatment of such states, a well-balanced intervention into the blood clotting system is required, and there is still a need for substances exhibiting a suitable pharmacological activity for achieving such a result.
Blood coagulation is a complex process involving a progressively amplified series of enzyme activation reactions in which plasma zymogens are sequentially activated by limited proteolysis. Mechanistically, the blood coagulation cascade has been divided into intrinsic and extrinsic pathways, which converge at the activation of factor X. Subsequent generation of thrombin proceeds through a single common pathway (see Scheme 1). Present evidence suggests that the intrinsic pathway plays an important role in the maintenance and growth of fibrin formation, while the extrinsic pathway is critical in the initiation phase of blood coagulation (H. Cole,
Aust. J. Med. Sci
. 16 (1995) 87-93; G. J. Broze,
Blood Coagulation and Fibrinolysis
6, Suppl. 1 (1995) S7-S13). It is generally accepted that blood coagulation is physically initiated upon formation of a factor VIIa/tissue factor (TF) complex. Once formed, this complex rapidly initiates coagulation by activating factors IX and X. The newly generated activated factor X, i.e., factor Xa, then forms a one-to-one complex with factor Va and phospholipids to form a prothrombinase complex, which is responsible for converting soluble fibrinogen to insoluble fibrin via the activation of thrombin from its precursor prothrombin. As time progresses, the activity of the factor VIla/TF complex (extrinsic pathway) is suppressed by a Kunitz-type protease inhibitor protein, TFPI, which, when complexed to factor Xa, can directly inhibit the proteolytic activity of factor VIIa/TF.
In order to maintain the coagulation process in the presence of an inhibited extrinsic system, additional factor Xa is produced via the thrombin-mediated activity of the intrinsic pathway. Thus, thrombin plays a dual autocatalytic role, mediating its own production and the conversion of fibrinogen to fibrin. The autocatalytic nature of thrombin generation is an important safeguard against uncontrolled bleeding and it ensures that, once a given threshold level of prothrombinase is present, blood coagulation will proceed to completion. Thus, it is most desirable to develop agents that inhibit coagulation without directly inhibiting thrombin but by inhibiting other steps in the coagulation cascade like factor VIIa activity.
In many clinical applications there is a great need for the prevention of intravascular blood clots or for some anticoagulant treatment. For example, nearly 50% of patients who have undergone a total hip replacement develop deep vein thrombosis (DVT). The currently available drugs like heparin and derivatives thereof are not satisfactory in many specific clinical applications. The currently approved therapies include fixed dose low molecular weight heparin (LMWH) and variable dose heparin. Even with these drug regimes, 10% to 20% of patients develop DVT, and 5% to 10% develop bleeding complications.
Another clinical situation for which better anticoagulants are needed concerns subjects undergoing transluminal coronary angioplasty and subjects at risk for myocardial infarction or suffering from crescendo angina. The present conventionally accepted therapy, which consists of administering heparin and aspirin, is associated with a 6% to 8% abrupt vessel closure rate within 24 hours of the procedure. The rate of bleeding complications requiring transfusion therapy due to the use of heparin also is approximately 7%. Moreover, even though delayed closures are significant, administration of heparin after termination of the procedures is of little value and can be detrimental.
The widely used blood-clotting inhibitors like heparin and related sulfated polysaccharides like LMWH and heparin sulfate exert their anti-clotting effects by promoting the binding of a natural regulator of the clotting process, anti-thrombin III, to thrombin and to factor Xa. The inhibitory activity of heparin primarily is directed toward thrombin, which is inactivated approximately 100 times faster than factor Xa. Hirudin and hirulog are two additional thrombin-specific anticoagulants presently in clinical trials. However, these anticoagulants which inhibit thrombin also are associated with bleeding complications. Preclinical studies in baboons and dogs have shown that targeting enzymes involved at earlier stages of the coagulation cascade, such as factor Xa or factor VIIa, prevents clot formation without producing the bleeding side effects observed with direct thrombin inhibitors (L. A. Harker et al.,
Thromb. Hemostas
. 74 (1995) 464-472). Certain peptides and peptide analogs which inhibit blood clotting by specifically inhibiting factor Xa are disclosed, for example, in WO-A-95/29189.
Specific inhibition of the factor VIIa/TF catalytic complex using monoclonal antibodies (WO-A-92/0671 1) or a protein such as chloromethyl ketone inactivated factor VIIa (WO-A-96/12800 and WO-A-97/47651) is an extremely effective means of controlling thrombus formation caused by acute arterial injury or the thrombotic complications related to bacterial septicemia. There is also experimental evidence suggesting that inhibition of factor VIIa/TF activity inhibits restenosis following balloon angioplasty (L. A. Harker et al.,
Hemostasis
26 (1996) S1:76-82). Bleeding studies have been conducted in baboons and indicate that inhibition of the factor VIIa/TF complex has the widest safety window with respect to therapeutic effectiveness and bleeding risk of any anticoagulant approach tested including thrombin, platelet, and factor Xa inhibition (L. A. Harker et al.,
Thromb. Hemostas
. 74 (1995) 464-472).
A specific inhibitor of factor VIIa which has a favorable property profile would have substantial practical value in the practice of medicine. In particular, a factor VIIa inhibitor would be effective under circumstances where the present drugs of choice, like heparin and related sulfated polysaccharides, are ineffective or only marginally effective. Certain inhibitors of factor VIIa have already been described, e.g., in WO-A-89/09612. EP-A-987274 discloses compounds cont

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