Janux Therapeutics Inc. (NASDAQ:JANX) stock hit a 52-week low on Tuesday after the company released updated interim data for its JANX007 Phase 1 program for metastatic castration-resistant prostate cancer (mCRPC).
As of October 15, 2025, data cutoff, 109 patients have been treated across the Phase 1a dose escalation and Phase 1b expansion trials of JANX007.
The patients enrolled in the Phase 1a trial were heavily pre-treated with a median of four prior lines of therapy. The patients enrolled in the Phase 1b expansion trial were taxane-naïve mCRPC.
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Patients from the Phase 1 trials demonstrated high prostate-specific antigen (PSA) response rates and deep PSA declines.
Anti-tumor activity was observed with confirmed and unconfirmed partial responses in 30% (8/27) of RECIST-evaluable patients.
Encouraging durability was observed in both the QW and every two-week (Q2W) expansions, with radiographic progression-free survival (rPFS) ranging from 7.9 to 8.9 months, and the rPFS of the Q2W expansion group compared favorably to the QW expansion group.
Preliminary Phase 1b data in taxane-naïve patients demonstrated rapid and deep PSA reductions with primarily grade 1 CRS. Additionally, tumor burden analysis suggests potential for improved rPFS in JANX007-treated earlier-line patients.
JANX007 demonstrated a manageable safety profile with cytokine release syndrome (CRS) primarily limited to cycle 1 and grades 1 and 2. Additionally, a CRS mitigation strategy was identified that maintains the grade 1 and 2 CRS profile.
Development Strategy
Janux is advancing JANX007 with a focus on monotherapy and darolutamide combinations in taxane-naïve mCRPC patients. Janux also plans to evaluate JANX007 in PARP inhibitor-refractory patients as a potential path to an expedited approval.
Analyst Commentary
William Blair on Tuesday wrote that Janux shares trading down is an overreaction based on looking at the totality of data across several different dosing regimens and CRS mitigation strategies.
The analyst Matt Phipps added, “While there are some fair criticisms, such as the decline in RECIST response rate and not disclosing confirmed versus unconfirmed responses, focusing on the cohorts 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 wrote that although specific timelines have not been given, we anticipate the next update with JANX007 from the Phase Ib trial will come in 2026 and will reestablish investor confidence in the program.
Analyst Phipps sees the sell-off as a buying opportunity and reiterates an Outperform rating.
JANX Price Action: Janux Therapeutics shares were down 47.82% at $17.73 at the time of publication on Tuesday, according to Benzinga Pro data.
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