Imlunestrant

Biotechnology firm Arvinas and partner Pfizer have struck a long-awaited licensing deal for their newly approved breast cancer drug.The companies on Tuesday inked an agreement transfering ownership of that medicine, Veppanu, to San Francisco-based biotech Rigel Pharmaceuticals. Arvinas and Pfizer will receive $75 million upfront, another $15 million after certain transition activities are completed, and are eligible for another $320 million in future payouts as well as sales royalties. In return, Rigel will get global rights to Veppanu, which includes the ability to partner off non-U.S. ownership. Formerly known as vepdegestrant, Veppanu earlier this month was approved in the U.S.as a treatment for certain people with a common form of breast cancer. In winning that clearance, Veppanu became the first drug of its kind a protein-trashing medicine known for short as a PROTAC to get to market.Arvinas and Pfizer had originally hoped Veppanu could help a broad group of breast cancer patients in multiple lines of care. However, the drug proved most beneficial in breast cancer patients with mutations to a gene called ESR1. Study data also didnt clearly separate Veppanu from other, similar hormone-degrading cancer drugs recently approved for breast tumors, such as Eli Lilly's Inluriyoand Menarinis Orserdu.Those factors led the partners to dial back their projections for Veppanu and look to offload the medicine rather than sell it. Theyd aimed to complete a deal before a regulatory approval was issued, though Arvinas CEO Randy Teel reassured investors the companies were well-situated if an alliance hadnt been struck by then.The transaction effectively enables Arvinas to move forward with a pipeline thats now built around other programs. It's not the blue-sky deal I wouldve hoped for, but the most important part of the deal is that its done, and focus can now fully move on, wrote Evercore ISI analyst Jon Miller, in a Tuesday note to clients.Founded in 1996, Rigel is best known for Tavalisse, a medicine used to treat a rare autoimmune disease known as chronic immune thrombocytopenia. With the addition of Veppanu, the company now has three other marketed cancer medicinesas well.With its novel mechanism of action designed to address a key driver of resistance, Veppanu represents a compelling treatment option within this setting,“ said Rigel CEO Raul Rodriguez, in a separate statement.Rodriguez said the therapy is expected to contribute strong revenue growth and has the potential to become a key revenue driver for the company going forward. '

The US FDA has approved Guardant360 CDx as a companion diagnostic for Veppanu (vepdegestrant), the PROTAC estrogen receptor degrader jointly developed by Arvinas and Pfizer, in patients with ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer. The liquid biopsy test, developed by Guardant Health, detects ESR1 mutations from a blood draw and is intended to identify patients eligible for treatment with Veppanu following progression on at least one prior line of endocrine therapy. The approval marks the third ESR1-related companion diagnostic designation for Guardant360 CDx and its 26th companion diagnostic indication across solid tumor types. Veppanu, which received FDA approval as a first-in-class PROTAC heterobifunctional protein degrader in oncology, is indicated for adults whose tumors harbor ESR1 mutations as detected by an FDA-authorized test, making the companion diagnostic designation a functional prerequisite for patient selection in clinical practice. ESR1 mutations are acquired resistance alterations that emerge in a substantial proportion of patients treated with aromatase inhibitors, particularly in combination with CDK4/6 inhibitors. Estimates cited in the approval context suggest that 40 to 50% of patients progressing on CDK4/6 inhibitor-based endocrine therapy may carry ESR1 mutations detectable in circulating tumor DNA. Because these mutations arise under selective pressure during treatment rather than being present at diagnosis, blood-based testing at the point of progression offers a practical advantage over tissue re-biopsy in capturing the current mutational state of the tumor. The companion diagnostic approval situates Guardant360 CDx within a competitive landscape for ESR1 mutation testing in advanced breast cancer. The platform had previously received companion diagnostic approvals linked to elacestrant (Orserdu) and imlunestrant (Inluriyo), the two oral selective estrogen receptor degraders that preceded Veppanu in gaining FDA approval for ESR1-mutated ER-positive, HER2-negative metastatic breast cancer. Elacestrant was approved in January 2023, imlunestrant in September 2025, and Veppanu in May 2026, compressing into roughly three years a transformation of the post-CDK4/6 inhibitor endocrine therapy landscape from a single injectable option in fulvestrant to three orally or mechanistically distinct agents. For Guardant Health, the approval extends the clinical utility of a platform that the company describes as covering more than 300 million lives through Medicare and commercial payer agreements. The test detects multiple genomic alterations across solid tumors and has accumulated companion diagnostic indications spanning non-small cell lung cancer, breast cancer, and colorectal cancer. The ESR1 mutation context is notable because it represents a biomarker that is dynamic rather than germline or constitutive, emerging during the course of metastatic disease and therefore requiring testing at or near the point of treatment selection rather than at initial diagnosis. The broader diagnostic question in this setting concerns whether liquid biopsy-based ESR1 testing is sufficiently integrated into routine oncology practice. Real-world data have suggested that ESR1 mutation testing rates remain inconsistent outside academic centers, and that a portion of patients who might benefit from ESR1-targeted therapy do not receive testing at disease progression. The availability of a blood-based test with a companion diagnostic designation tied to an approved therapy provides a regulatory and reimbursement framework that may support more systematic testing, though the extent to which that translates into practice change depends on factors beyond the approval itself. From a competitive standpoint, the three approved ESR1-targeted agents — elacestrant, imlunestrant, and vepdegestrant — each carry companion diagnostic requirements or recommendations that reference liquid biopsy or tissue-based ESR1 detection. Guardant360 CDx now holds companion diagnostic status for all three, a position that reflects both the platform’s regulatory track record and the consolidation of ESR1 testing around a small number of validated assays. The sequencing of these agents in clinical practice, and whether prior exposure to one oral endocrine agent affects the activity of another, remains an open clinical question without prospective cross-resistance data. This article was generated with AI assistance and reviewed and edited by the AllSci editorial team Explore more at AllSci News: https://allsci.com/news/ Your email address will not be published. Required fields are marked * Comment * Name * Email * Website