Biotech Stocks Rally After-Hours On Trial Updates, Insider Buys, And Conference Buzz

(RTTNews) - Biotech stocks lit up the after-hours session on September 9, 2025, with several small- and mid-cap names posting sharp gains following fresh clinical updates, insider buying, and investor conference appearances. Companies like Immutep, Nautilus Biotechnology, Pliant Therapeutics, Phio Pharmaceuticals, and Kura Oncology all saw renewed momentum, driven by near-term catalysts that are drawing attention across the healthcare sector. Here's a quick look at the biggest movers and what's fueling their post-market rallies.

Shares of Immutep Ltd. (IMMP) rose by 4.37%, reaching $1.67 in after-hours trading. This rebound followed a sharp decline during regular market hours, where the stock closed at $1.60, down 6.98% from the previous session.

The most recent news came on September 9, 2025, when Immutep announced that data from its EFTISARC-NEO Phase II trial has been accepted for oral presentation at CTOS 2025, a major oncology conference scheduled for November. This trial is the first to evaluate eftilagimod alpha (efti) in a neoadjuvant setting for soft tissue sarcoma (STS), combining efti with radiotherapy and KEYTRUDA (pembrolizumab). The trial, conducted in Poland and funded by the Polish Medical Research Agency, targets a rare cancer with high unmet need and poor prognosis. The presentation is scheduled for November 13, 2025, and will highlight primary endpoints and translational correlates.

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Shares of Nautilus Biotechnology Inc. (NAUT) surged by 12.25%, rising to $0.7521 in after-hours trading. This sharp rebound followed a disappointing regular session, where the stock closed at $0.6700, down 4.42%.

The most recent catalyst came from insider buying activity. On September 8, 2025, CEO Sujal M. Patel purchased 83,500 shares of Nautilus stock, following an earlier acquisition of 116,500 shares on September 5. These transactions, totaling over $135,000, signal confidence from the company's leadership and have drawn attention from investors seeking undervalued biotech plays.

Additionally, Nautilus is scheduled to participate in the Q3 Investor Summit Group Virtual Conference on September 16-17.

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Shares of Pliant Therapeutics Inc. (PLRX) ended the regular trading session on September 9, 2025, at $1.75, up 1.16% for the day. In after-hours trading, the stock jumped sharply by 16.00%, reaching $2.03. This strong post-market move reflects heightened attention around the company's upcoming milestones.

The next key event on the calendar is the company's third-quarter earnings report, scheduled for November 6, 2025. Updates are expected on bexotegrast, Pliant's lead candidate targeting idiopathic pulmonary fibrosis, along with progress across its broader fibrosis-focused pipeline.

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Shares of Jin Medical International Ltd. (ZJYL) closed at $0.6532 on September 9, 2025, marking a gain of 3.65% during regular trading hours. In after-hours trading, the stock extended its rally, rising 7.15% to $0.6999.

The most recent catalyst came from the company's announcement of expanded production capabilities. In August 2025, Jin Medical launched operations at Plant No. 3 in Chuzhou, China, aimed at accelerating global delivery of its medical equipment, including wheelchairs and rehabilitative devices. This expansion is expected to enhance supply chain efficiency and support international growth, particularly in markets such as the United States, Japan, and Southeast Asia.

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Phio Pharmaceuticals Corp. (PHIO) saw a notable surge in after-hours trading on September 9, 2025, with its stock rising 8.20% to $2.64. This move extended the momentum from the regular session, where shares had already climbed 13.49% to close at $2.44. The continued rally highlights increased focus on the company's clinical pipeline and near-term visibility.

The most recent catalyst is Phio's participation in the H.C. Wainwright 27th Annual Global Investment Conference, taking place from September 8 to 10, 2025 in New York City. CEO Robert Bitterman is scheduled to present on September 10, offering updates on the company's ongoing Phase 1b clinical trial for PH-762, an INTASYL siRNA compound targeting PD-1 in skin cancers such as cutaneous squamous cell carcinoma, melanoma, and Merkel cell carcinoma. The presentation is expected to outline strategic next steps following the treatment phase of the study.

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Shares of Kura Oncology Inc. (KURA) jumped 6.12% in after-hours trading on September 9, 2025, reaching $8.50 after closing the regular session at $8.01, down 1.60%. The post-market rally reflects renewed focus on the company's advancing pipeline and upcoming regulatory milestones.

The most recent catalyst came from Kura's presentation at the H.C. Wainwright 27th Annual Global Investment Conference on September 8, 2025. CEO Troy Wilson outlined key developments, including preparations for the PDUFA action date on November 30 for Ziftomenib, a menin inhibitor targeting relapsed/refractory NPM1-mutant acute myeloid leukemia (AML). Two Phase 3 trials are also underway, evaluating Ziftomenib in frontline AML settings, with the potential to tap into a market opportunity exceeding $7 billion annually.

In addition, Kura is advancing its Farnesyl Transferase Inhibitor (FTI) program, with Phase 1 data expected to be presented at ESMO. This program targets resistance mechanisms in solid tumors and complements the company's broader oncology strategy.

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