Rapport Therapeutics, Inc. (Nasdaq: RAPP) announced on October 20, 2026, that its Phase 2 trial of RAP-219 for the treatment of acute bipolar mania met its primary endpoint. The randomized, double-blind, placebo-controlled trial was conducted in the United States and enrolled 253 adults with bipolar I disorder experiencing a manic episode.

The trial met its primary endpoint, with RAP-219 achieving a statistically significant 3.1-point placebo-adjusted improvement in the Young Mania Rating Scale (YMRS) total score at Week 3. Patients treated with RAP-219 showed a mean reduction of 15.4 points from a baseline of 36.9, compared to a reduction of 12.3 points in the placebo group. The difference was statistically significant with a p-value of 0.045. Additionally, RAP-219 demonstrated a statistically significant improvement in the Clinical Global Impression—Bipolar Version (CGI-BP) mania severity scale, a pre-specified secondary endpoint (0.4 points; p=0.024).

According to the filing, all 11 YMRS items improved on RAP-219 compared to placebo at Week 3, with improvements in irritability, thought content, disruptive-aggressive behavior, and sexual interest reaching nominal significance. The data indicates progressive improvement in YMRS scores over the three-week treatment period.

Regarding safety, RAP-219 was well-tolerated during the three-week treatment period. The incidence of treatment-emergent adverse events (TEAEs) was similar between the RAP-219 group (51.6%) and the placebo group (52.8%). All TEAEs were mild or moderate in severity, and there were no serious adverse events (SAEs). The most common TEAEs in the RAP-219 group included agitation, insomnia, restlessness, anxiety, headache, and nausea. Adverse effects commonly associated with current bipolar medications, such as orthostatic hypotension, akathisia, and extrapyramidal symptoms, were not reported.

Rapport plans to meet with the U.S. Food and Drug Administration (FDA) in the first quarter of 2027 to discuss the Phase 2 data and registrational trial design. The company expects to initiate two Phase 3 pivotal trials of RAP-219 in acute bipolar mania in the second half of 2027.

As of June 30, 2026, Rapport reported having $436.1 million in cash, cash equivalents, and short-term investments, excluding restricted cash, which is expected to fund operations into the second half of 2029.