Biotech Stocks Surge After Hours On Trial Updates And Strategic Moves

(RTTNews) - After-hours trading on Tuesday featured a wave of notable price moves across the biotech and therapeutics space, with several small- and mid-cap names posting sharp gains following clinical updates, strategic announcements, or upcoming trial milestones. While regular session activity was mixed, post-market momentum reflected renewed attention to pipeline developments and near-term catalysts. Below is a roundup of key after-hours gainers.

Shares of Cyclerion Therapeutics, Inc. (CYCN) surged 48.01% in after-hours trading, climbing from $3.02 to $4.47 by 11:53 PM EDT. The move followed the company's announcement of a strategic relaunch centered on neuropsychiatric therapies, including a licensing agreement with MIT to support its lead program targeting treatment-resistant depression or TRD.

Earlier in the regular session, CYCN closed at $3.02, down 0.66% from the previous close of $3.04. Despite the modest decline during market hours, the after-hours spike reflects renewed attention to the company's updated direction.

Looking ahead, Cyclerion expects to initiate a Phase 2 proof-of-concept trial for its TRD program in 2026, with initial data anticipated in 2027.

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Clearside Biomedical Inc. (CLSD) saw a strong move in after-hours trading, rising 6.82% to $4.23 following a regular session close of $3.96. During the regular trading session, CLSD declined 9.79%, to close at $3.96. The stock traded within a range of $3.96 to $4.57, with volume reaching 75,803 shares, well below its average of 310,837.

The recent price action follows Clearside's presentations at the EURETINA Congress, where the company highlighted subgroup analyses from its Phase 2b ODYSSEY trial of CLS-AX for wet age-related macular degeneration. With those sessions now concluded, the next key catalyst is the formal initiation of the CLS-AX Phase 3 trial, which is expected to incorporate FDA feedback and focus on suprachoroidal delivery advantages.

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Shares of Reviva Pharmaceuticals Holdings Inc. (RVPH) rose 11.50% to $0.32 in the after-hours trading session, following a regular session close of $0.287. During the regular trading session, RVPH declined 6.61%, falling from an open of $0.311 to close at $0.287. The stock traded within a range of $0.2835 to $0.32, with volume reaching 10.36 million shares, well above its average of 3.77 million.

The price action comes ahead of Reviva's participation in the Lytham Partners Fall 2025 Investor Conference, scheduled for Tuesday, September 30, at 10:15 AM ET.

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Acumen Pharmaceuticals, Inc. (ABOS) advanced 5.69% in after-hours trading to $1.30, following a regular session close of $1.23. During the day, ABOS declined 3.91%, falling from an open of $1.27 to close at $1.23. The stock traded within a range of $1.22 to $1.305, with volume reaching 252,034 shares, below its average of 415,895.

Recently, the company reported second-quarter financial results and confirmed that topline data from the Phase 2 ALTITUDE-AD trial of sabirnetug (ACU193) remains on track for late 2026. Acumen also reiterated plans to decide on advancing a preclinical candidate from its Enhanced Brain Delivery program in early 2026, developed in collaboration with JCR Pharmaceuticals.

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PepGen Inc. (PEPG) rose 5.13% in after-hours trading to $2.05, following a regular session close of $1.95. During the day, PEPG declined 8.02%, to close at $1.95. The stock traded within a range of $1.95 to $2.23, with volume reaching 450,032 shares, slightly above its average of 427,585.

Recently, the company completed patient dosing in the 15 mg/kg cohort of its Phase 1 FREEDOM-DM1 trial evaluating PGN-EDODM1 for myotonic dystrophy type 1. PepGen remains on track to report topline safety, splicing, and functional data from this cohort in early Q4 2025. Clinical sites are now transitioning to the Phase 2 multiple ascending dose study, FREEDOM2-DM1, with initial results from the first dose cohort expected in Q1 2026.

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Corcept Therapeutics Inc. (CORT) gained 4.54% in after-hours trading to $87.10, following a regular session close of $83.32. During the day, CORT rose 4.15%, to close at $83.32. The stock traded within a range of $79.78 to $84.50, with volume reaching 912,642 shares, slightly below its average of 1.05 million.

Recently, the company announced it will present late-breaking data from its pivotal Phase 3 ROSELLA trial of relacorilant plus nab-paclitaxel in platinum-resistant ovarian cancer at the 2025 European Society for Medical Oncology (ESMO) Annual Meeting. The presentation, scheduled for October 19, will focus on outcomes in patients previously treated with PARP inhibitors, a subgroup with limited treatment options.

Corcept also confirmed two upcoming Prescription Drug User Fee Act (PDUFA) dates: December 30, 2025, for relacorilant in hypercortisolism, and July 11, 2026, for relacorilant in platinum-resistant ovarian cancer.