According to a media release issued today by GenSpera, Inc., the U.S. Food & Drug Administration (FDA) has approved the proposed structure of a small, non-randomized, Phase II clinical trial of G-202 for the treatment of men with metastatic, castration-resistant prostate cancer (mCRPC).
The media release states that the company expects to conduct this trial “at up to six sites in the United States and the United Kingdom” and expects to enroll about 40 patients with chemotherapy-naïve mCRPC. However, there is no information yet about when or where the trial will actually start to enroll patients because the trial still needs approval from institutional review boards (IRBs) at the currently proposed clinical sites. Nor do we yet know the dose level of the drug that will be used in the Phase II clinical trial announced today.
There was a good deal of media “noise” about G-202 recently (see, for example, “‘Death carrot’ comes to cancer“) — based on minimal information related to a very early (Phase Ia) clinical study. Back in March, Genspera announced that G-202 had been tested in 28 people with “advanced solid tumors” (i.e., not necessarily advanced forms of prostate cancer) who participated in a Phase I clinical study. They were treated with doses ranging from 1.2 mg/m2 (~2 mg) up to 88 mg/m2 (~150 mg) per dose. According to that announcement, “The drug exposure in patients receiving the higher doses of G-202 falls within the range associated with anti-tumor efficacy in animal models.” To date, however, there has been no formal announcement or publication of the results of this Phase I study. We don’t even know how many of the participants had prostate cancer.
G-202 is an investigational drug that has been developed from extracts of a plant called Thapsia garganica. However, it is by no means a “natural product.” Like many, many other pharmaceuticals, it is a product that has been significantly modified from a naturally occurring agent in a specific plant. Detailed information about the development and pre-clinical data on the activity of G-202 was published in Science Translational Medicine by Denmeade et al. back in June and was followed by a media release from Johns Hopkins in July. G-202 is a combination of a naturally occurring product called thapsigargin, described by Genspera as “a powerful, plant-derived cytotoxin” (so it is by no means benign) and what they call “a prodrug delivery system that appears to release the drug only within the tumor.”
It is worth noting that GenSpera has three other drugs in development for the treatment of prostate cancer, but none of these have yet been tested in humans. It is also worth noting that early studies on the development of G-202 have been supported by grants from the Prostate Cancer Research Program of the Department of Defense’s Congressionally Directed Medical Research Programs (which we regularly ask our US-based readers to tell their Congressmen and Congresswomen to support).