Rapport Therapeutics Slides Despite Positive Seizure Drug Data
Shares fall over 6% in a 'sell-the-news' reaction as investors weigh promising Phase 2a results for epilepsy drug RAP-219 against its development timeline.
Shares of Rapport Therapeutics, Inc. (RAPP) fell more than 6% on Monday, a surprising downturn after the company announced positive topline results from a Phase 2a clinical trial for its leading drug candidate, RAP-219, for treating focal onset seizures.
The market's bearish reaction appears to be a classic case of 'sell-the-news,' where the positive, and perhaps anticipated, results were overshadowed by the long road still ahead for the treatment. Despite the stock's decline, the clinical data itself was robust and statistically significant.
The successfully met its primary endpoint, demonstrating a clinically meaningful impact on patients with drug-resistant focal epilepsy. According to the company, patients treated with RAP-219 achieved a 77.8% median reduction in clinical seizures. Furthermore, an impressive 24% of patients achieved complete seizure freedom during the eight-week treatment period.
RAP-219, a potential first-in-class TARPγ8-specific AMPAR negative allosteric modulator, was also generally well-tolerated, with most adverse events reported as mild to moderate. "The efficacy data and tolerability profile seen in the Phase 2a trial demonstrate RAP-219's potential to be an important treatment for patients with drug-resistant focal onset seizures," said Abe Ceesay, chief executive officer of Rapport. He added that the company believes the drug could address a significant unmet need for patients.
Despite the strong clinical showing, investors seem focused on the development timeline. Rapport stated it plans to hold an end-of-Phase 2 meeting with the U.S. Food and Drug Administration (FDA) in late 2025 and does not expect to initiate the pivotal until the third quarter of 2026. This multi-year timeline before the drug could potentially reach the market may be tempering immediate investor enthusiasm.
Dr. Jacqueline French, the study's principal investigator, praised the results, stating, "The magnitude of the reduction in clinical seizure frequency seen in this trial... give me confidence that a medication like RAP-219 has the potential to be a highly effective" treatment. Rapport is also exploring RAP-219 for other neurological conditions, including bipolar mania and diabetic peripheral neuropathic pain, signaling its .