On Apr. 7, 2026, Cornell scientists announce they have taken a major step toward developing a safe, reversible, long-acting and 100% effective nonhormonal male contraceptive, considered the holy grail of male contraception. A proof of principle study in mice, six years in the making, shows how targeting a natural checkpoint in meiosis, the process by which sex cells reproduce, safely stopped sperm production. 

The researchers made use of JQ1, a small molecule inhibitor that was developed as a research tool to study cancer and inflammatory disease. Because of its neurological side effects, it wasn’t a viable therapy for disease, or as a final contraceptive, but it’s known to disrupt a stage of meiosis called prophase 1. This enabled Cornell researchers to provide the first proof of principle that meiosis – and sperm production – can be targeted safely and reversibly. 

Stephanie Tanis and Leah Simon, both Ph.D. ’25, and currently postdoctoral researchers at Colorado University, are the paper’s co-first authors, while Cohen is senior author of the study appearing in the Proceedings of the National Academy of Sciences. “Our study shows that mostly we recover normal meiosis and complete sperm function, and more importantly, that the offspring are completely normal,” Cohen said. 

Currently, male contraceptives include condoms and vasectomies. Many men are wary of vasectomies, the only long-acting option for men, and they are technically reversible through subsequent surgery. Researchers have been especially reluctant to develop a hormonal contraceptive, as such treatments have proven potentially dangerous in women.

Moving forward, Cohen is considering new targets in meiosis that disrupt the process earlier, just at the entry into prophase 1, which would further ensure that no sperm survive. Targeting an earlier phase in the process would also improve drug delivery, due to the development of the blood testes barrier, which protects later stages of sperm development, from prophase 1. 

In next steps, the team is working towards testing three new gene targets. “We have three targets that when knocked out, we know they absolutely obliterate meiosis and the mice have no sperm, and functionally and biologically, those mice are very healthy,” Cohen said. Now they are working to show these candidates can be targeted in a reversible way. 

Cohen and colleagues intend to launch a company within the next two years to continue developing these methods. A male contraceptive would likely start in the form of an injection taken every three months, or possibly a patch, to ensure effectiveness, Cohen said.