Novartis Discontinues Phase 2 GRPR-Targeted Radioligand Lu-NeoB in Breast Cancer, Reaffirms Platform Commitment
Key Insights
Novartis has halted all studies of its GRPR (search)-targeted radioligand therapy Lu-NeoB (search), though the decision was not driven by negative clinical data or safety concerns.
The discontinuation reflects the increasingly high bar in HR+/HER2− metastatic breast cancer (search), where ADCs, CDK4/6 inhibitors, and oral SERDs are reshaping the treatment landscape.
Novartis stated its commitment to radioligand therapy remains unchanged, with a pipeline still targeting PSMA (search), DLL3 (search), HER2 (search), and fibroblast activation protein.
Novartis has quietly discontinued development of Lu-NeoB (search), its gastrin-releasing peptide receptor (GRPR (search))-targeted radioligand therapy, across all ongoing studies in metastatic breast cancer. The decision, confirmed by a company spokesperson to Fierce Biotech, was not prompted by new or unexpected safety signals, nor does it appear to reflect negative clinical efficacy data. Instead, the move underscores how dramatically the treatment paradigm for HR-positive, HER2 (search)-negative breast cancer has evolved — and how high the bar for new entrants has risen.
The Swiss pharmaceutical giant had been investigating Lu-NeoB (search), which uses lutetium-177 to deliver targeted radiation to tumors expressing GRPR (search), across multiple clinical trials. These included a Phase 1 study combining the radioligand with ribociclib and fulvestrant, as well as a Phase 1/2 trial evaluating Lu-NeoB alongside the chemotherapy agent capecitabine in metastatic ER-positive, HER2 (search)-negative breast cancer. Patients already enrolled in these studies will continue to receive treatment according to their respective trial protocols.
A Strategic Retreat, Not a Scientific Failure
Matthew Kurian, Staff Oncologist at St. Elizabeth Healthcare, contextualized the decision on LinkedIn, noting that the discontinuation "does not appear to reflect negative clinical data." Rather, he observed, "it underscores how high the bar has become in breast cancer, with ADCs, CDK4/6 inhibitors, oral SERDs, and other targeted therapies rapidly reshaping the treatment landscape."
Novartis did not disclose the specific efficacy results that informed the decision. The company's spokesperson emphasized to Fierce Biotech that the discontinuation was not caused by a new or unexpected safety issue, leaving open questions about whether the efficacy threshold in the context of an increasingly crowded therapeutic field simply proved too challenging to meet.
Radioligand Platform Commitment Intact
Despite the setback, Novartis has made clear that its broader commitment to radioligand therapy remains unchanged. The modality, which delivers cytotoxic radiation directly to tumor cells by targeting specific surface receptors, has already yielded two approved products for the company: Pluvicto, targeting PSMA (search) in prostate cancer, and Lutathera, addressing neuroendocrine tumors.
Lu-NeoB (search) represented one of Novartis' more advanced efforts to expand radioligand therapy beyond these established indications by targeting a new tumor-associated receptor. GRPR (search) is found at elevated levels in certain breast cancers and other solid tumors, making it a biologically plausible target for this approach.
The company's radioligand pipeline continues to include candidates directed at PSMA (search), DLL3 (search), HER2 (search), and fibroblast activation protein (FAP), signaling that the platform remains a strategic priority even as individual programs are reassessed.
The Evolving Breast Cancer Landscape
The discontinuation raises broader questions about where radioligand therapy might ultimately fit within breast cancer treatment. As Kurian noted, "The question isn't whether radioligands have a future in breast cancer — but which target, which patients, and where they'll fit in an increasingly crowded treatment paradigm."
With antibody-drug conjugates (ADCs), CDK4/6 inhibitors, and oral selective estrogen receptor degraders (SERDs) continuing to demonstrate robust clinical benefit, any new modality must demonstrate compelling differentiation to secure a role. Novartis' decision suggests that for GRPR (search)-directed radioligand therapy in this specific breast cancer population, that threshold was not met — at least not with the current approach.
Kurian expressed continued optimism about the modality's potential in breast cancer, while acknowledging the uncertainty about its optimal positioning. The path forward for radioligands in this tumor type may depend on identifying more precisely defined patient subgroups, novel targets, or combination strategies that can offer advantages over the expanding arsenal of available therapies.