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NX-1607 demonstrated on-target peripheral immune activation characteristic of an active immune-oncology agent with a novel immune checkpoint mechanism distinct from PD-1/PD-L1 therapies
NX-1607 demonstrated evidence of monotherapy anti-tumor activity with reductions in tumor biomarkers, tumor shrinkage, long-term stable disease, and a confirmed partial response in heavily pretreated patients
Data support initiation of expansion cohorts at the two highest doses tested as monotherapy or combination for the treatment of advanced solid tumors
Nurix Therapeutics, Inc. (Nasdaq: NRIX), a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of targeted protein degradation medicines, today announced the presentation of new clinical data from its first-in-human Phase 1a study of NX-1607, a first-in-class oral inhibitor of the E3 ligase Casitas B-lineage lymphoma proto-oncogene B (CBL-B) in patients with relapsedrefractory solid tumors. The data are being presented at the European Society for Medical Oncology Congress (ESMO 2025), taking place October 17–21, 2025, in Berlin, Germany.
"As a first-in-class oral inhibitor of CBL-B, NX-1607 may offer a novel therapeutic approach to treat solid tumors by targeting a previously unaddressed pathway in immune regulation affecting not only T cells, but also multiple immune cell types, including dendritic cells and natural killer cells, which all play critical roles in the tumor microenvironment," said Paula O'Connor, M.D., chief medical officer of Nurix. "These data highlight NX-1607's activity as an immuno-oncology agent, showing promising signs of biologic activity and clinical benefit, and supporting its continued development as an innovative next generation checkpoint inhibitor therapy designed to improve outcomes for cancer patients."
In a poster titled: First-in-Class CBL-B Inhibitor NX-1607: Phase 1a Data in Patients with Advanced Solid Tumors , data were presented from a total of 82 patients with eleven different tumor types treated across six once-daily (QD) and five twice-daily (BID) dosing regimens ranging from 5 mg to 80 mg total daily dose. Patients were heavily pre-treated with a median of 3 prior regimens including a median of 1 prior chemo/immunotherapy regimen. NX-1607 demonstrated dose-dependent exposure, increases in proximal and distal biomarkers, evidence of peripheral immune activation, and reductions in tumor volume and cancer biomarkers. Despite the advanced stages of disease and the broad range of tumor types included in the trial, NX-1607 demonstrated evidence of clinical activity including reductions in tumor-specific biomarkers (prostate-specific antigen (PSA) in prostate cancer and carcinoembryonic antigen (CEA) in colorectal cancer), long-term stable disease, and a confirmed partial response in a patient with micro-satellite stable colorectal cancer (MSS CRC), a tumor type typically unresponsive to immune checkpoint therapy. As of the 26 July 2025 data cut, 71 patients were evaluable for response, with a disease control rate (DCR) of 49.3%. With respect to duration of response, 7 patients achieved either stable disease (SD) or partial response (PR) for ≥5 months on treatment and 1 patient with MSS CRC achieved a PR and was treated for 27 months. Further supporting the dose-dependent activity of NX-1607, the greatest reductions in PSA among the prostate cancer patients were achieved in the BID dosing groups with 6/13 patients having PSA reductions of ≥50%.
NX-1607 was shown to be tolerable at pharmacologically active doses and has a safety profile comparable to approved immuno-oncology agents, with most adverse events Grade 2 or less in severity. Immune-related adverse events were observed in 6 patients, indicating on-target immune activation, similar to what is observed with PD-1/PD-L1 therapies. The most common treatment emergent adverse events included nausea and vomiting, which were mitigated by both BID dosing and the introduction of a step-up dosing regimen where patients were initially treated at lower doses and increased to the target dose during the first cycle of treatment.
"NX-1607 has demonstrated potent single agent activity preclinically and now most importantly, we see clear signals of anti-tumor activity in patients with advanced disease. The results are particularly intriguing in MSS colorectal cancer and metastatic prostate cancer, two important indications where current immunotherapies have failed to demonstrate efficacy," said Arthur T. Sands, M.D., Ph.D., president and chief executive officer of Nurix. "We look forward to further exploring the broad therapeutic potential of NX-1607 while we advance our lead asset bexobrutideg, an oral BTK degrader, into pivotal trials in patients with relapsed or refractory chronic lymphocytic leukemia."
About NX-1607
NX-1607 is an investigational first-in-class oral inhibitor of the E3 ligase Casitas B-lineage lymphoma proto-oncogene B (CBL-B) being developed for immuno-oncology indications, including a range of solid tumor types. CBL-B is a cytoplasmic E3 ubiquitin ligase that negatively regulates T cell activation, making it an attractive target for immuno-oncology and offering a novel therapeutic approach to treat solid tumors. Inhibition of CBL-B in preclinical studies reverses T cell exhaustion, alleviates tumor-induced immunosuppression, and may also exert direct antitumor effects. Nurix is evaluating NX-1607 in an ongoing Phase 1 trial in adults in a range of oncology indications. This study includes a thorough investigation of both dose and schedule in the Phase 1a portion. Additional information on the NX-1607 clinical trial can be accessed at www.clinicaltrials.gov ( NCT05107674 ).
About Nurix Therapeutics, Inc.
Nurix Therapeutics is a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of targeted protein degradation medicines, the next frontier in innovative drug design aimed at improving treatment options for patients with cancer and inflammatory diseases. Nurix's wholly owned, clinical stage pipeline includes degraders of Bruton's tyrosine kinase (BTK), a B-cell signaling protein, and inhibitors of Casitas B-lineage lymphoma proto-oncogene B (CBL-B), an E3 ligase that regulates activation of multiple immune cell types including T cells and NK cells. Nurix also is advancing multiple potentially first-in-class or best-in-class degraders and degrader antibody conjugates (DACs) in its preclinical pipeline. Nurix's partnered drug discovery pipeline consists of a preclinical stage degrader of STAT6, a clinical stage degrader of IRAK4, as well as multiple additional programs under collaboration agreements with Gilead Sciences, Inc., Sanofi S.A. and Pfizer Inc., within which Nurix retains certain options for co-development, co-commercialization and profit sharing in the United States for multiple drug candidates. Powered by a fully AI-integrated discovery engine capable of tackling any protein class, and coupled with unparalleled ligase expertise, Nurix's dedicated team has built a formidable advantage in translating the science of targeted protein degradation into clinical advancements. Nurix aims to establish degrader-based treatments at the forefront of patient care, writing medicine's next chapter with a new script to outmatch disease. Nurix is headquartered in San Francisco, California. For additional information visit http://www.nurixtx.com .
Forward-Looking Statements
This press release contains statements that relate to future events and expectations and as such constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements that reflect Nurix's expectations, assumptions or projections about the future are forward-looking statements, including, without limitation, statements regarding the therapeutic potential of NX-1607, Nurix's plans for the clinical development of NX-1607, Nurix's plans for its other clinical assets, including bexobrutideg, and the planned timing for the provision of updates and findings from Nurix's clinical trials. Forward-looking statements reflect Nurix's current beliefs, expectations, and assumptions. Although Nurix believes the expectations and assumptions reflected in such forward-looking statements are reasonable, Nurix can give no assurance that they will prove to be correct. Forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and changes in circumstances that are difficult to predict, which could cause Nurix's actual activities and results to differ materially from those expressed in any forward-looking statement. Such risks and uncertainties include, but are not limited to: (i) whether Nurix will be able to advance, obtain regulatory approval of and ultimately commercialize NX-1607; (ii) whether Nurix will be able to fund development activities and achieve development goals; (iii) whether Nurix will be able to protect intellectual property and (iv) other risks and uncertainties described under the heading "Risk Factors" in Nurix's Quarterly Report on Form 10-Q for the fiscal quarter ended August 31, 2025, and other SEC filings. Accordingly, readers are cautioned not to place undue reliance on these forward-looking statements. The statements in this press release speak only as of the date of this press release, even if subsequently made available by Nurix on its website or otherwise. Nurix disclaims any intention or obligation to update publicly any forward-looking statements, whether in response to new information, future events, or otherwise, except as required by applicable law.
Contacts:
Investors
Kris Fortner
Nurix Therapeutics, Inc.
mailto: kfortner@nurixtx.com
Elizabeth Wolffe, Ph.D.
Wheelhouse Life Science Advisors
lwolffe@wheelhouselsa.com
Media
Aljanae Reynolds
Wheelhouse Life Science Advisors
areynolds@wheelhouselsa.com
