Janux Therapeutics Craters 50% On Prostate Cancer Update;...

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Janux Therapeutics Craters 50% On Prostate Cancer Update; Is It An 'Overreaction'?

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ALLISON GATLIN
10:10 AM ET 12/02/2025

Janux Therapeutics (JANX) stock crashed Tuesday in what one analyst called an "overreaction" to the biotech company's updated test results for a prostate cancer treatment.

The company tested its drug, JANX007, in patients with castration-resistant prostate cancer who had received a median of four prior treatments. Of the 27 patients who could be evaluated, 30% responded to the treatment. That's down from 50% in the previous update a year ago. But the earlier analysis included just eight patients.

Still, analysts remained upbeat on Janux's chances.

"Focusing on the (groups) of patients treated with dosing regimens advancing to Phase Ib and initial data in patients with lower tumor burden continue to suggest JANX007 has the potential to achieve a best-in-disease profile and achieve blockbuster sales," William Blair analyst Matt Phipps said in a note.

But in early trades, Janux shares collapsed more than 47% to 17.62. Shares opened at their lowest point since February 2024.

Janux Therapeutics: PSA In Focus

Importantly, patients who received JANX007 had lower PSA scores. PSA, or prostate specific antigen, is elevated in patients with prostate cancer. Among 89 patients who received two doses of JANX007, 73% hit PSA50. That means their PSA scores dropped by 50%. More than a quarter, 26%, achieved a 90% drop in PSA levels following treatment.

That drove strong progression-free survival trends. Progression-free survival, or PFS, is the length of time patients live before their cancer worsens. At the median, PFS was 7.3 months. Among those given the dose heading into additional testing, the PFS was 7.9 months.

The numbers are generally in line with rival drugs from Amgen (AMGN) and Johnson & Johnson (JNJ), said Phipps, the William Blair analyst.

He said Janux Therapeutics is testing out an updated protocol to improve the incidence of cytokine release syndrome, or CRS, a dangerous inflammatory response to some cancer drugs. The company didn't disclose the specifics of these regimens for competitive reasons. But one of the protocols led to no serious cases of CRS and just one mild case.

"Acknowledging these are fairly small patient (groups), reproducing this CRS profile in ongoing studies would be very encouraging and likely result in a therapy that can be given in the outpatient setting," Phipps said.

Shares Undercut Key Lines

Phipps kept his outperform rating on Janux Therapeutics shares.

But Wedbush analyst Robert Driscoll slashed his price target on Janux stock to 45 from 76. He still rates shares an outperform. The price-target cut is due to the expected timeline for JAN007, Driscoll said in a report to clients.

Janux shares have climbed recently, rising almost 63% from a recent low at 21.73 in late September to a high at 35.34 late this month. That has resulted in an improved IBD Digital Relative Strength Rating of 86. The RS Rating tracks a stock's 12-month performance on a 1-99 scale, pitting it against all other stocks. Janux's RS Rating has improved from 7 three months ago.

But the move Tuesday put shares below their 50-day and 200-day moving averages, according to MarketSure.

Follow Allison Gatlin on X/Twitter at @AGatlin_IBD.

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