Zai Lab’s DLL3-Targeting ADC Receives FDA Orphan Drug Designation for Neuroendocrine Carcinomas
Zai Lab Limited has announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to its investigational antibody-drug conjugate (ADC), zocilurtatug pelitecan (zoci, formerly known as ZL-1310), for the treatment of neuroendocrine carcinomas (NECs). The designation represents another important regulatory milestone for the company’s oncology pipeline and underscores the growing recognition of zoci’s potential to address a significant unmet medical need in patients with these rare and aggressive cancers.
Neuroendocrine carcinomas are uncommon but highly aggressive malignancies that often progress rapidly and are associated with poor survival outcomes. Patients diagnosed with recurrent or advanced NECs have limited treatment options, particularly after failure of initial therapy. There are currently no approved targeted therapies specifically indicated for previously treated NECs, highlighting the urgent need for innovative therapeutic approaches capable of improving outcomes for this patient population.
The FDA’s Orphan Drug Designation is intended to encourage the development of therapies for rare diseases and conditions affecting fewer than 200,000 people in the United States. By granting this designation to zocilurtatug pelitecan, the agency acknowledges both the rarity of neuroendocrine carcinomas and the potential value of the investigational therapy in addressing an area where current treatment options remain inadequate.
Advancing a Novel DLL3-Targeted Therapy
Zocilurtatug pelitecan is being developed as a potential first-in-class Delta-like ligand 3 (DLL3)-targeting antibody-drug conjugate. DLL3 has emerged as a promising therapeutic target because it is highly expressed in several aggressive neuroendocrine cancers while showing minimal expression in most normal healthy tissues. This differential expression makes DLL3 an attractive target for precision oncology therapies designed to selectively attack tumor cells while minimizing damage to normal tissues.
Antibody-drug conjugates combine the targeting ability of monoclonal antibodies with the cancer-killing activity of potent cytotoxic agents. The antibody component identifies and binds to a specific protein expressed on cancer cells—in this case DLL3—allowing the chemotherapy payload to be delivered directly into malignant cells. This targeted mechanism aims to maximize anti-tumor activity while potentially reducing systemic toxicity compared with conventional chemotherapy.
Researchers believe DLL3-directed therapies could significantly improve treatment options for patients with neuroendocrine malignancies, many of whom currently receive standard chemotherapy regimens that often produce only temporary responses before disease progression occurs.
Addressing a Significant Unmet Medical Need
Neuroendocrine carcinomas represent one of the most aggressive forms of neuroendocrine tumors. They can develop in multiple organs throughout the body, including the gastrointestinal tract, pancreas, bladder, prostate, and other tissues. Many patients are diagnosed after the disease has already spread, making treatment particularly challenging.
Unlike well-differentiated neuroendocrine tumors, NECs tend to grow rapidly and frequently develop resistance to existing therapies. Survival rates remain poor, especially for patients whose disease progresses following first-line platinum-based chemotherapy.
The absence of approved targeted therapies has prompted increasing interest in novel approaches such as DLL3-targeted antibody-drug conjugates. If clinical development continues successfully, zocilurtatug pelitecan could potentially become one of the first precision medicines specifically designed for patients with DLL3-expressing neuroendocrine cancers.
Company Highlights Global Regulatory Progress
Commenting on the FDA decision, Rafael G. Amado, M.D., President and Head of Global Research and Development at Zai Lab, said the latest designation further strengthens the growing body of regulatory support the investigational medicine has received worldwide.
According to Dr. Amado, zoci has now earned several important regulatory recognitions across multiple regions, reflecting its potential to become an important treatment option for patients with various DLL3-expressing cancers. He emphasized that the company remains committed to efficiently advancing the clinical development of the investigational therapy to bring new treatment options to patients facing limited therapeutic choices.
Dr. Amado also noted that patients diagnosed with neuroendocrine carcinomas continue to experience substantial unmet medical needs due to the lack of targeted therapies and limited effective options after standard treatment failure. The company therefore intends to continue progressing its development programs while working closely with global regulatory authorities.
Previous FDA Designations Support Development
The newly granted Orphan Drug Designation builds upon a series of previous regulatory milestones achieved by zocilurtatug pelitecan.
Earlier, the FDA granted Fast Track Designation (FTD) to the investigational ADC for the treatment of extrapulmonary neuroendocrine carcinomas (epNECs). Fast Track status is intended to facilitate the development and expedite the review of therapies addressing serious conditions with unmet medical needs.
In addition, the FDA previously awarded both Fast Track Designation and Orphan Drug Designation to zoci for the treatment of small cell lung cancer (SCLC).
Small cell lung cancer represents the most common pulmonary neuroendocrine carcinoma and remains among the deadliest forms of lung cancer. Despite advances in immunotherapy, long-term survival rates remain low, and many patients eventually experience disease progression after initial treatment.
These multiple regulatory recognitions demonstrate increasing confidence in the therapeutic potential of DLL3-targeted treatment strategies across different neuroendocrine malignancies.
European Regulatory Recognition
Beyond the United States, zocilurtatug pelitecan has also received regulatory support in Europe.
The European Medicines Agency (EMA) has granted Orphan Drug Designation for the investigational therapy in pulmonary neuroendocrine carcinomas, providing additional momentum for the global development program.
The coordinated regulatory progress across major healthcare markets highlights the international interest in developing targeted therapies for rare neuroendocrine cancers and supports broader clinical development efforts.
Benefits of Orphan Drug Designation
Receiving Orphan Drug Designation provides several important incentives designed to encourage continued drug development.
Among the benefits are eligibility for:
- Waiver of certain FDA application fees under the Prescription Drug User Fee Act (PDUFA)
- Tax credits covering qualified clinical research expenses
- Regulatory support throughout development
- Potential eligibility for seven years of market exclusivity in the United States if the product ultimately receives FDA approval for the designated indication
These incentives are intended to help biotechnology companies invest in therapies for diseases that affect relatively small patient populations, where commercial development can be especially challenging.
Although Orphan Drug Designation does not guarantee regulatory approval, it provides valuable support that can facilitate continued clinical research and regulatory interactions.
Continued Clinical Development
Zai Lab continues to advance clinical studies evaluating zocilurtatug pelitecan across multiple DLL3-expressing cancers. The company is investigating the ADC in indications where DLL3 expression is common and current treatment options remain limited.
The broader development strategy reflects growing scientific interest in DLL3 as a promising biomarker for precision oncology. As research advances, investigators hope that targeted therapies directed against DLL3 may improve response rates and survival outcomes while offering a more personalized treatment approach for patients with aggressive neuroendocrine malignancies.
The latest FDA designation further strengthens the clinical development program and supports Zai Lab’s efforts to expand treatment options for patients diagnosed with rare and difficult-to-treat cancers. If ongoing and future clinical trials continue to demonstrate favorable efficacy and safety, zocilurtatug pelitecan could become an important addition to the evolving landscape of targeted cancer therapies for neuroendocrine carcinomas and other DLL3-expressing malignancies.
About Zocilurtatug Pelitecan (Zoci, ZL-1310)
Zoci targets Delta-like ligand 3 (DLL3), a validated therapeutic target that is overexpressed in many neuroendocrine carcinomas, such as small cell lung cancer (SCLC) and extrapulmonary neuroendocrine carcinomas (epNEC), and is generally associated with poor clinical outcomes. Zoci is on track to potentially become Zai Lab’s first global oncology launch, with plans for three registration-enabling studies across second- and third-line SCLC, first-line SCLC, and epNECs by the end of 2026.
Its potential best-in-class safety profile, coupled with compelling systemic and intracranial efficacy, support its potential role as a new standard of care in previously treated extensive-stage SCLC as well as epNEC, and a backbone DLL3-targeting antibody-drug conjugate (ADC) in first-line combination regimens, including those that reduce the burdens of chemotherapy, such as checkpoint inhibitors and T-cell engagers.
About Zai Lab
Zai Lab Limited (NASDAQ: ZLAB; HKEX: 9688) is an innovative, research-based, commercial-stage biopharmaceutical company based in China and the United States. We are focused on discovering, developing, and commercializing innovative products that address medical conditions with significant unmet needs in the areas of oncology, immunology, neuroscience, and infectious disease. Our goal is to leverage our competencies and resources to positively impact human health.