Data from first patient cohort provide human proof-of-concept and support continued dose escalation in patients with small cell lung cancer and large cell neuroendocrine carcinoma
Pharmacokinetic, dosimetry, and imaging data demonstrate selective tumor uptake and rapid clearance from blood and kidneys
ABD-147 tolerated at initial dose level, with early evidence of disease stabilization in advanced disease
SOUTH SAN FRANCISCO, Calif.–(BUSINESS WIRE)–Abdera Therapeutics Inc., a clinical-stage biopharmaceutical company leveraging its advanced antibody engineering ROVEr™ platform to design and develop tunable precision radiopharmaceuticals for cancer, today announced initial clinical data from its ongoing Phase 1a trial of ABD-147 in patients with small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC) that support continued dose escalation. The data were presented in a poster session at the IASLC 2025 World Conference on Lung Cancer in Barcelona, Spain.
ABD-147 is a targeted radiopharmaceutical biologic therapy designed to deliver Actinium-225 (225Ac), a potent alpha-emitting isotope, to solid tumors expressing delta-like ligand 3 (DLL3) with high affinity. DLL3 is expressed in approximately 85% of patients with SCLC, an intrinsically radiosensitive cancer.
“These data with ABD-147 validate the mechanistic promise of DLL3-targeted alpha radiotherapy and mark an important step toward a modality that could reshape SCLC treatment,” said Lisa Bodei, M.D., Ph.D., Nuclear Medicine Physician and Early Drug Development Specialist at Memorial Sloan Kettering Cancer Center. “While early, at the first dose level, we observed selective tumor uptake, predicted biodistribution without evidence of alteration, and disease stabilization in advanced disease following platinum-based therapy. These findings support continued dose escalation and further evaluation in SCLC, where treatment options remain limited.”
Phase 1a Trial Overview and Key Findings
The Phase 1 trial is designed to evaluate the safety and tolerability, pharmacokinetics (PK), and preliminary anti-tumor activity of 225Ac-ABD147 in patients with locally advanced or metastatic SCLC and LCNEC following platinum-based chemotherapy. Dosimetry analysis using Indium-111 (111In) was conducted to track ABD-147 distribution in the body and to measure radiation doses to organs.
Data as of data cutoff date of August 15, 2025 from a total of six patients enrolled in the first dose cohort demonstrate:
- PK: Human PK was consistent with preclinical models in multiple species, with minimal inter-patient variability
- Biodistribution: Favorable tumor uptake with rapid clearance from the blood and key organs, including the kidneys
- Dosimetry: Projected administered activity of 225Ac-ABD147 across all planned doses is within established safety limits for all organs, including kidneys, liver and bone marrow
- Imaging: CT confirmed ABD-147 uptake in target lesions, supporting DLL3 specificity
- Safety: ABD-147 has been tolerated, with no infusion-related events, no dose modifications and no dose-limiting toxicities observed to date. Treatment-related adverse events included one case of paresthesia (tingling sensation) that resolved rapidly, and one case of thrombocytopenia. Five serious adverse events were observed in two patients – three instances of dyspnea and two deaths due to co-morbidities – all of which were deemed unrelated to study drug.
- Preliminary anti-tumor activity: Disease stabilization has been observed, including one patient who received multiple cycles of ABD-147 with over four months of follow-up.
Based on these initial data, the independent safety review committee recommended continuation of dose escalation with ABD-147.
“The presentation of our first-in-human data for ABD-147 marks an important milestone for Abdera and reinforces the promise of our precision radiopharmaceuticals for difficult-to-treat cancers,” said Philippe Bishop, M.D., chief medical officer of Abdera Therapeutics. “These data highlight the power of our ROVEr™ platform to engineer finely tunable radiopharmaceuticals with optimal tumor accumulation and healthy tissue clearance. I am incredibly proud of the team’s work to bring ABD-147 to this important stage. As we advance dose escalation, our focus remains on unlocking the full potential of ABD-147 for patients with DLL3-expressing tumors.”
About ABD-147
ABD-147 is a targeted radiopharmaceutical biologic therapy designed to deliver Actinium-225 (225Ac), a highly potent alpha-emitting radioisotope, to solid tumors expressing delta-like ligand 3 (DLL3) with high affinity. DLL3 is a protein in the Notch pathway that is critical for the development and regulation of neuroendocrine versus epithelial cell differentiation in the lungs. In certain high grade neuroendocrine carcinomas including small cell lung cancer (SCLC), DLL3 is upregulated and specifically expressed on the cell surface in more than 80% of cases. In contrast, DLL3 is absent or very rarely expressed on the surface of nonmalignant cells. Given the high specificity of DLL3 expression on cancer cells and the distinct mechanism of action, DLL3 represents a compelling target for treating SCLC and other DLL3+ solid tumors with targeted radiotherapy.
The U.S. Food and Drug Administration (FDA) has granted Fast Track designation to ABD-147 for the treatment of patients with extensive stage small cell lung cancer (ES-SCLC) who have progressed on or after platinum-based chemotherapy and Orphan Drug Designation to ABD-147 for the treatment of neuroendocrine carcinoma. ABD-147 is currently being evaluated in a first-in-human Phase 1 clinical trial in patients with SCLC or large cell neuroendocrine carcinoma of the lung who have previously received platinum-based therapy.
About Small Cell Lung Cancer and Large Cell Neuroendocrine Carcinoma
The global incidence for SCLC and LCNEC has been reported to represent approximately 325,000 patients and is expected to increase 4% annually through 2029. In the U.S., the incidence has been reported to be approximately 35,000 new cases annually. Fifteen percent of all lung cancer cases are high-grade neuroendocrine cancers. These cancers have the most aggressive clinical course of any type of pulmonary tumor and often metastasize to other parts of the body, including the brain, liver and bone. Without treatment, the median survival from diagnosis has been reported to be only two to four months. With treatment, the overall survival at five years is 5% to 10% for SCLC, and 15% to 25% for LCNEC. SCLC and LCNEC generally carry a poor prognosis and new treatment options are urgently needed.
About Abdera
Abdera Therapeutics is a clinical-stage biopharmaceutical company leveraging antibody engineering to design and develop new precision radiopharmaceuticals for cancer. Abdera’s Radio Optimized Vector Engineering (ROVEr™) proprietary platform enables the company to engineer potential best-in-class therapies for both clinically validated and novel targets that deliver potent radioisotopes capable of emitting alpha or beta particles to selectively destroy cancer cells. Abdera’s lead program, ABD-147, is a next-generation precision radiopharmaceutical biologic therapy designed to deliver Actinium-225 (225Ac) to solid tumors expressing delta-like ligand 3 (DLL3) for the treatment of small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC). Headquartered in South San Francisco, CA, Abdera also has offices in Vancouver, British Columbia, Canada. To learn more, please visit www.abderatx.com and follow us on LinkedIn and X.
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