Y-Mabs Therapeutics Stock Price, News & Analysis

Y-mAbs Therapeutics, Inc. (YMAB) is a commercial-stage biopharmaceutical company that focuses on the development and commercialization of novel radioimmunotherapy and antibody-based therapeutic products for the treatment of cancer. According to multiple company disclosures, Y-mAbs concentrates particularly on high-risk and difficult-to-treat oncology indications, with an emphasis on pediatric oncology and other tumors that express specific molecular targets.

The company’s lead commercial asset is DANYELZA® (naxitamab-gqgk), an anti-GD2 therapy. Company materials describe DANYELZA as the first U.S. Food and Drug Administration (FDA)-approved treatment for patients with relapsed or refractory high-risk neuroblastoma in the bone or bone marrow after a partial response, minor response, or stable disease to prior therapy. DANYELZA is indicated, in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), for pediatric patients one year of age and older and adult patients with this form of high-risk neuroblastoma. The approval was granted under the FDA’s accelerated approval pathway based on overall response rate and duration of response, with continued approval potentially contingent on confirmatory clinical benefit.

Y-mAbs states that it has organized its operations around two business units: a DANYELZA segment centered on commercialization of naxitamab-gqgk, and a Radiopharmaceuticals segment focused on its radioimmunotherapy platforms and pipeline. The company reports commercial distribution of DANYELZA in the United States and through partners in various ex-U.S. regions, and it highlights named patient programs and distribution collaborations as part of its commercial footprint.

Radioimmunotherapy and SADA PRIT Platform

A core element of Y-mAbs’ strategy is its investigational Self-Assembly DisAssembly (“SADA”) Pretargeted Radioimmunotherapy Platform (“PRIT”). Company descriptions explain that SADA-based agents are bispecific fusion proteins designed to bind both a tumor-associated antigen and a chelated radionuclide. The approach separates the targeting protein infusion from the subsequent infusion of the radioactive payload.

In the first step of pretargeted radioimmunotherapy, non-radiolabeled SADA tetramers are infused and bind to antigen-positive tumor cells, while unbound protein disassembles into low molecular weight monomers that are cleared by the kidney. In the second step, a radiolabeled payload (for example, 177Lu-DOTA) is administered and binds to the SADA protein localized on tumor cells, delivering localized irradiation. Y-mAbs reports that this architecture is intended to improve tumor-to-normal tissue dose ratios compared with directly labeled antibodies, based on preclinical pharmacokinetic and dosimetry data.

The company’s disclosures describe two main SADA-based development programs:

• GD2-SADA PRIT (Trial 1001): a first-in-human, dose-escalation, single-arm, open-label, multicenter Phase 1 clinical trial in adults and adolescents with recurrent or refractory metastatic solid tumors known to express GD2, including high-risk neuroblastoma, small cell lung cancer, sarcomas, and melanoma. Part A of Trial 1001 evaluates dose escalation of the GD2-SADA protein and the interval between GD2-SADA and 177Lu-DOTA. Company-reported Part A data indicate that GD2-SADA and 177Lu-DOTA administrations were generally safe and well tolerated, with no treatment-related serious adverse events reported across dosing cohorts, and that positive tumor uptake and quantifiable absorbed dose to tumor were observed at certain dose levels.
• CD38-SADA PRIT (Trial 1201): a Phase 1, dose-escalation, open-label, single-arm, multicenter study in adults with relapsed, progressive, or refractory non-Hodgkin lymphoma (NHL) that expresses CD38 after at least two prior lines of therapy. Company materials explain that CD38-SADA is a bispecific fusion protein that binds CD38 and 177Lu-DOTA. The trial is designed to investigate pretargeted delivery of the CD38-SADA protein followed by a 177Lu-DOTA payload, with Part A focused on dose escalation, imaging, and dose-limiting toxicities.

Y-mAbs also reports preclinical and translational pharmacokinetic modeling work for CD38-SADA, including characterization of the equilibrium between tetramers and monomers and simulations used to inform first-in-human dosing. The company highlights that low molecular weight monomers clear more rapidly than tetramers, which is relevant for limiting off-tumor radiation exposure.

Pipeline and Oncology Focus Areas

In addition to DANYELZA and its lead SADA programs, Y-mAbs describes a broader oncology pipeline. Company updates note that the radiopharmaceutical development strategy includes target franchises in lung cancer, women’s cancers, and gastrointestinal cancers, along with a discovery and pre-IND molecular imaging portfolio designed to complement therapeutic programs. Y-mAbs has stated plans to advance additional SADA-based assets and to file regulatory submissions for molecular imaging candidates on defined timelines, while emphasizing that these plans are subject to the inherent uncertainties of drug development.

The company’s disclosures also emphasize that its platforms and product candidates are investigational unless otherwise approved, and that forward-looking statements around development timelines, regulatory interactions, and potential clinical benefits are subject to significant risks and uncertainties as outlined in its SEC filings.

Regulatory and Clinical Recognition of DANYELZA

Beyond FDA accelerated approval, Y-mAbs reports that naxitamab-gqgk (DANYELZA) has been recommended by the National Comprehensive Cancer Network® (NCCN®) Clinical Practice Guidelines in Oncology for Neuroblastoma as a Category 2A treatment option for high-risk neuroblastoma. Company communications characterize this guideline inclusion as reinforcing the role of DANYELZA as an anti-GD2 therapy for relapsed or refractory high-risk neuroblastoma in the bone or bone marrow in patients who have achieved at least stable disease with prior therapy.

Y-mAbs notes that DANYELZA carries a boxed warning for serious infusion-related reactions, including cardiac arrest and anaphylaxis, and for neurotoxicity, including severe neuropathic pain and transverse myelitis. The company directs readers to the full prescribing information for complete boxed warning and safety details and states that DANYELZA is not approved for osteosarcoma in any jurisdiction.

Corporate Developments, Acquisition, and Trading Status

Y-mAbs Therapeutics, Inc. was previously listed on the Nasdaq Global Select Market under the ticker symbol YMAB. On August 4, 2025, the company entered into an Agreement and Plan of Merger with Perseus BidCo US, Inc. (Parent), Yosemite Merger Sub, Inc. (Purchaser), and Stark International Lux, as disclosed in a Form 8-K. Under that agreement, Parent, which is affiliated with SERB Pharmaceuticals, agreed that Purchaser would commence a cash tender offer to acquire all outstanding shares of Y-mAbs common stock at a price of $8.60 per share in cash, followed by a merger in which Y-mAbs would become a wholly owned subsidiary of Parent.

A subsequent Form 8-K dated September 16, 2025 reports that the tender offer expired on September 15, 2025, with approximately 87.22% of outstanding shares validly tendered and not withdrawn. Purchaser accepted for payment all tendered shares and, on September 16, 2025, completed a merger with Y-mAbs under Section 251(h) of the Delaware General Corporation Law. As a result, Y-mAbs survived as a wholly owned subsidiary of Parent under the name “Y-mAbs Therapeutics, Inc.” and each outstanding share (other than specified excluded shares) was converted into the right to receive the same cash consideration as in the tender offer.

The same Form 8-K explains that, in connection with the merger, Y-mAbs requested that Nasdaq suspend trading in its common stock effective at the open of trading on September 16, 2025 and that Nasdaq file a Form 25 to remove the shares from listing and registration under Section 12(b) of the Securities Exchange Act of 1934. A Form 25-NSE filed on September 16, 2025 by Nasdaq Stock Market LLC confirms the notification of removal from listing and/or registration of Y-mAbs common stock on Nasdaq. A subsequent Form 15 filed on September 26, 2025 certifies the termination of registration under Section 12(g) of the Exchange Act and suspension of Y-mAbs’ duty to file periodic reports under Sections 13 and 15(d). The Form 15 notes that the approximate number of holders of record at the certification date was one.

These filings indicate that YMAB is a former Nasdaq-listed security. The company continues to exist as a private, wholly owned subsidiary of Parent following its acquisition by an affiliate of SERB Pharmaceuticals, but its common stock is no longer listed on Nasdaq and its reporting obligations under the Exchange Act have been suspended.

Research and Development Orientation

Across its public communications, Y-mAbs characterizes itself as research-intensive, with a focus on translating antibody engineering and radioimmunotherapy science into therapeutic candidates. The company highlights collaborations and licensing arrangements, including exclusive licenses from Memorial Sloan Kettering Cancer Center (MSK) for SADA technology and for naxitamab-gqgk. Company disclosures note that MSK and certain researchers hold intellectual property rights and institutional financial interests related to these technologies.

Y-mAbs’ R&D updates emphasize:

• First-in-human clinical experience with its SADA PRIT platform, including pharmacokinetics, dosimetry, and safety observations in GD2-SADA and CD38-SADA programs.
• Optimization work on radiohapten design, including a universal radiohapten referred to as “Proteus” intended to support theranostic applications across multiple isotopes.
• Plans to expand the radiopharmaceutical pipeline into additional solid tumor and hematologic indications, subject to regulatory and clinical progress.

In its forward-looking statements, the company underscores that drug development is costly, time-consuming, and uncertain, and that clinical success, regulatory approvals, reimbursement, and integration with SERB’s specialty pharmaceutical platform are all subject to risks described in its SEC filings.

Position Within Biotechnology and Professional Services Sector

Within the broader classification of Research and Development in Biotechnology and the Professional, Scientific, and Technical Services sector, Y-mAbs represents a specialized oncology-focused biopharmaceutical enterprise. Its activities span discovery research, preclinical development, clinical trials, regulatory interactions, and commercial operations for an FDA-approved biologic. The company’s emphasis on antibody-based therapeutics and pretargeted radioimmunotherapy situates it in a niche that combines biologics, radiopharmaceuticals, and precision oncology.

From a structural perspective, Y-mAbs’ business model, as described in its public materials, links revenue generation from DANYELZA with ongoing investment in pipeline programs, particularly those based on the SADA PRIT platform. Following its acquisition by an affiliate of SERB Pharmaceuticals and delisting from Nasdaq, Y-mAbs operates as a private subsidiary within a larger specialty pharmaceutical group that focuses on rare diseases, rare oncology, and emergency medicine.