The excuse for not using ivermectin in the NIH site is that the donations were growing so fast they were trying to fund more research of other medicines.

"Therefore, this review summarized the latest findings on the anticancer effect of IVM and discussed the mechanism of the inhibition of tumor proliferation and the way that IVM induces tumor programmed cell death to provide a theoretical basis for the use of IVM as a potential anticancer drug. As the cost of the research and development of new anticancer drugs continues to increase, drug repositioning has become increasingly important. Drug repositioning refers to the development of new drug indications that have been approved for clinical use [28]. For some older drugs that are widely used for their original indications and have clinical data and safety information, drug repositioning allows them to be developed via a cheaper and faster cycle and to be used more effectively in clinical use clinically [29]. Here, we systematically summarized the anticancer effect and mechanism of IVM, which is of great significance for the repositioning of IVM for cancer treatment."