Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving transferase
Reexamination Certificate
2000-03-03
2003-05-27
Gitomer, Ralph (Department: 1651)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving transferase
C435S069200, C435S184000
Reexamination Certificate
active
06569638
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is a method for identifying compounds potentially useful for the selective treatment and prevention of pre-cancerous and cancerous lesions in mammals, as well as pharmaceutical compositions containing such compounds.
For many years, researchers have sought compounds that selectively treat neoplastic cells without substantial growth-inhibiting adverse effects on normal cells. Conventional cancer chemotherapeutics—regardless of the type of cancer against which they have been directed—share one common feature: conventional compositions (e.g. herceptin, taxol, cisplatin, tamoxifen etc), to the extent they have any substantial effects on neoplastic cells—virtually always have significant adverse effects on normal tissues. Many of the side effects are debilitating and life-threatening. Thus, conventional chemotherapeutics are typically administered only after the neoplasia has significantly progressed to the stage where the drug side effects clearly outweigh the risks of no chemotherapy.
Conventional chemotherapeutics also typically are used to treat fairly specific types of neoplasias. For example, leuprolide is commonly prescribed to treat advanced prostate cancer, but not colon or lung cancers. Compositions with activities against broader ranges of neoplasias are desired.
In Pamukcu et al., in U.S. Pat. No. 5,401,774, compounds such as those now known as exisulind are disclosed for anti-neoplastic purposes. Contrary to conventional chemotherapeutics, such compounds are very selective against neoplastic cells as opposed to normal cells. Thus, such compounds can be administered on a chronic basis without the side effects normally associated with conventional chemotherapeutics. In addition, because of their safety profile, such compounds can be administered at the earliest stages of disease. Thus, new compounds have become recognized as a new class of antineoplastics known as selective apoptotic anti-neoplastic drugs (“SAANDs”).
Besides outstanding safety advantages over conventional chemotherapeutics, SAANDs also have a wider range of therapeutic application compared to conventional chemotherapeutics. For example, the first SAAND, exisulind, has been reported to have anti-neoplastic effects on colon, breast, lung, prostate, kidney, and melanoma neoplasias. It also has effects on other neoplasias.
SAANDs have the further advantage over anti-neoplastic NSAIDS (e.g., sulindac) because, unlike NSAIDs, SAANDs do not inhibit COXI/II enzymes. Inhibition of COX I and/or COX II enzymes (e.g., by indomethacin, celecoxib and other NSAIDs) lead to considerable side effects when taken on a chronic basis. In addition, COX inhibition is unnecessary for anti-neoplastic efficacy. Not surprisingly, many such COX I and COX II inhibitors also have not been demonstrated to have significant anti-neoplastic activities. The side effects of COX I and COX II inhibitors include gastric irritations that can lead to severe ulceration, and kidney toxicities. Since SAANDs antineoplastic therapy is enhanced with chronic or long-term administration, the COX inhibitors—to the extent any exhibit anti-neoplastic properties—are inappropriate simply because of safety considerations, since few patients can realistically take COX inhibitors chronically or long-term. For inflammation, COX inhibitors are commonly used only on a short-term or acute basis as a result.
How SAANDs can work without the side effects of COX inhibitors (or the even more severe side effects of conventional chemotherapeutics) remained a mystery until recently. As reported in U.S. Pat. No. 5,858,694, SAANDs work, in part by the inhibition of PDE5, which appears to be a necessary part of how SAANDs induce apoptosis (a form of cell death) in neoplastic, but not in normal cells. It was also discovered that SAANDs work by increasing cGMP and reducing cAMP in neoplastic cells, also as reported in the '694 patent.
However, it was later discovered that some PDE5 inhibitors did not induce apoptosis (see, e.g. U.S. patent application Ser. No. 09/173,375 filed Oct. 15, 1998). In the '375 application, the discovery of a new cGMP-specific PDE found in neoplastic cells was first reported. One observation that separated anti-neoplastic PDE5 inhibitors from inactive PDE5 inhibitors was that the anti-neoplastic PDE5 inhibitors inhibited the new cGMP-specific PDE, whereas the inactive PDE5 inhibitors (e.g., sildenafil) had little relative effect. This observation, as disclosed in the '375 application, led to more accurate drug discovery screening methods to identify active, anti-neoplastic PDE5 inhibitors (i.e. additional SAANDs).
However, more accurate and alternative methods to evaluate and identify compounds for their usefulness as SAANDs are desired.
SUMMARY OF THE INVENTION
This invention relates to a novel method for screening and identifying compounds for their usefulness as SAANDs. In particular, this invention provides a method for identifying compounds that can be used to treat and prevent neoplasia, including precancerous lesions, with minimal side effects associated with COX inhibition and other non-specific interactions associated with conventional chemotherapeutics.
In the course of researching why some PDE5 inhibitors induced apoptosis, we discovered that those that do induce apoptosis do so by ultimately activating JNK1 kinase activity. JNK is a proline-directed kinase of the MAP kinase extended family. It is believed that this effect is caused upstream of the JNK apoptotic pathway by the regulation of cGMP and cAMP by pro-apoptotic PDE5 inhibitors, as taught in U.S. Pat. No. 5,858,694 to Piazza et al. This connection between cGMP/cAMP regulation and JNK1 activity was surprising, and forms a useful way of ascertaining whether a cGMP inhibitor is a SAAND. In contrast to this effect on JNK kinase activity, tested SAANDs caused only slight activation of ERK2 kinase activity, a related but separate pathway of signal transduction commonly reported to play a role in stimulating cell proliferation.
This invention involves evaluating whether a compound causes an increase in cGMP-dependent protein kinase G (“PKG”) activity and activates JNK1 kinase in neoplastic cells. We believe that the elevation of PKG activity is due at least in part by the increase in cGMP caused by SAANDs inhibition of the appropriate PDEs, as described above.
The other characteristics of SAANDs are (1) inhibition of PDE5 as reported in the '694 patent above, (2) inhibition of the novel cGMP-specific PDE conformation, (3) inhibition of PDE2; (4) the fact that SAANDs increase intracellular cGMP in neoplastic cells, and (5) the fact that they decrease cAMP levels in some types of neoplastic cells.
Thus, one embodiment of the novel method of this invention is evaluating whether a compound activates JNK, causes PKG activity to elevate in neoplastic cells and whether that compound inhibits PDE5. Another embodiment of the novel screening method of this invention is evaluating whether a compound that activates JNK, causes PKG activity to elevate in neoplastic cells and whether that compound inhibits the novel cGMP-specific PDE described above and/or PDE2. Still a third embodiment is evaluating whether a compound activates JNK, causes PKG activity to elevate in neoplastic cells and whether that compound causes cGMP to rise in neoplastic cells and/or causes cAMP levels to fall. Compounds successfully evaluated in such fashions have application as SAANDs.
Among other things, this invention relates to novel in vitro and in vivo methods for selecting compounds for their ability to treat and prevent neoplasia, especially pre-cancerous lesions, safely. In particular, the present invention is a method for selecting compounds that can be used to treat and prevent neoplasia, including precancerous lesions. The compounds so identified can have minimal side effects attributable to COX inhibition and other non-specific interactions associated with conventional chemotherapeutics. The compounds of interest can be tested by exposing neoplastic cel
Li Han
Liu Li
Soh Jae-Won
Thompson W. Joseph
Weinstein I. Bernard
Cell Pathways Inc
Gitomer Ralph
Stevenson Robert W.
LandOfFree
Method for screening compounds for the treatment of neoplasia does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for screening compounds for the treatment of neoplasia, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for screening compounds for the treatment of neoplasia will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3021640