Temozolomide belongs to a family of tetrazine derivatives that were developed in the 1980s by the now obsolete UK company May and Baker. The first US patent application was filed by May and Baker in 1982, but was rejected because it relied on animal data to show potential clinical effects. When an application is rejected, an applicant can modify the application and present it again to the US Patent and Trademark Office (PTO), who reassess the application. But, rather than do this, a new application was filed. This cycle of initial rejections and new applications was repeated numerous times until the early 1990s.
Around this time, May and Baker decided not to pursue the development of temozolomide, and passed it on to Cancer Research Technology (the plaintiffs in this case), who had previously sponsored a Phase I trial of the compound that had shown positive results, albeit with some toxicity. But because the charity could not commercialize temozolomide, it entered into a licensing agreement with Schering Corporation (now Merck), who took on the responsibility of securing a patent.
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