A First-in-human (FIH), Phase 1 Study of ML261, an Autologous Potency Enhanced Anti-DLL3 CAR T Cell Therapy, in Participants With R/R SCLC or Select NECs (SPECTRAL-1)

NCT07488923 | Not Yet Recruiting Phase 1 FDA Drug

• 1 other identifier: ML261-101
• Study Type: interventional
• Target: 110
• Locations: 1 country
• Sites: 5

Brief Summary

This is a first-in-human (FIH), open-label, Phase 1 study designed to evaluate the safety, pharmacokinetics (PK), and preliminary efficacy of ML261, an autologous potency enhanced anti-DLL3 CAR T cell therapy, in participants with R/R SCLC or select NECs

Conditions

Small Cell Lung Cancer (SCLC ); Extrapulmonary Neuroendocrine Carcinoma (EP-NEC); Gastroenteropancreatic NEC (GEP NEC); Neuroendocrine Prostate Cancer (NEPC)

Keywords

Neuroendocrine carcinoma; DLL3; CAR T

Outcome Measures

Primary Outcomes (1)

• Incidence of dose-limiting toxicities (DLTs) listed during the DLT observation period

  Graded according to Common Terminology Criteria for Adverse Events (CTCAE) or American Society for Transplantation and Cell Therapy (ASTCT) criteria

  28 days

Secondary Outcomes (3)

• Incidence of treatment-emergent AEs (TEAEs), Grade ≥3 TEAEs, serious AEs (SAEs), and AEs of special interest (AESIs). Clinically significant laboratory abnormalities / changes from baseline in safety laboratory test results

  Through study completion; up to 2 years

• Characterize the molecular pharmacokinetic (PK) profile of ML261 after dosing

  Through study completion; up to 2 years

• Evaluate the preliminary efficacy of ML261 after dosing

  Through study completion; up to 2 years

Other Outcomes (1)

• Evaluate the immunogenicity of ML261 after dosing

  Through study completion; up to 2 years

Study Arms (1)

ML261

EXPERIMENTAL

DLL3-Directed Chimeric Antigen Receptor T cells (CAR T)

Biological: ML261

Interventions

ML261 BIOLOGICAL

DLL3 directed autologous Chimeric Antigen Receptor T cells

ML261

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• ≥18 years of age at the time of signing the ICF
• Have been previously treated with at least one line of systemic standard of care (SOC) anti-cancer therapy for their respective cancer indication. Participants with locally advanced disease who are eligible for curative resection will be excluded.
• Have documented radiological disease progression/relapse during or after their most recent line of anti-cancer therapy with measurable disease on imaging, as assessed by RECIST v1.1
• Have histologically and/or cytologically confirmed diagnosis of select advanced or metastatic R/R solid tumor malignancy in one of the following: R/R SCLC, R/R GEP-NEC, R/R high-grade NEPC, R/R epNEC with biopsy-documented DLL3 expression on archival tissue or fresh biopsy by local or central assessment. CNS NEC is excluded. Participants with mixed histologies for any of these indications qualify if the small cell/neuroendocrine tumor cell percentage is \> 50%, except for high-grade NEPC where neuroendocrine component must be \> 20%.
• Eastern Cooperative Oncology Group (ECOG) Performance Score (PS) 0 or 1
• Life expectancy ≥12 weeks
• Have adequate hematologic and end-organ function

You may not qualify if:

• Previous systemic anti-cancer therapies within the timeframes, as specified in the protocol.
• Prior exposure/treatment with DLL3-targeted CAR T therapy or any other genetically engineered adoptive T cell therapy.
• Prior allogeneic organ transplant (including allogeneic bone marrow transplant).
• Major surgical procedure within 4 weeks of the first dose of any study drug administration or anticipated to be in need of a major surgical procedure during the course of study.
• Participants with toxicities (as a result of prior anti-cancer therapy) which have not recovered to baseline or CTCAE v5.0 \<Grade 2, except for adverse events (AEs) not considered a likely safety risk: (e.g., alopecia, neuropathy, non-clinically relevant laboratory abnormalities).
• Symptomatic ascites or effusions (pleural or pericardial) requiring intermittent drainage.
• History of any other malignancy known to be active, with the exception of completely removed in situ cervical intra-epithelial neoplasia, non-melanoma skin cancer, ductal carcinoma in situ, early-stage prostate cancer that has been adequately treated, and other cancers from which the participant has been disease free for 3 years or longer or does not require treatment and in the opinion of investigator after discussion with the medical monitor are not likely to impact the patient's life expectancy.
• One or more of the following cardiac criteria: Unstable angina, Myocardial infarction within 6 months prior to Screening, New York Heart Association Class III to IV heart failure, clinically important abnormalities in rhythm, conduction, or morphology of resting ECG (e.g., complete left bundle branch block or third-degree heart block)
• Acute venous thromboembolism (VTE). VTEs without hemodynamic compromise, treated with stable doses of anticoagulants are allowed.
• Presence of clinically significant CNS pathology:
• seizure disorder, aphasia, stroke, severe brain injuries, dementia, Parkinson's disease, or cerebellar disease. History of these disorders requires discussion with the medical monitor.
• Presence of clinically active psychosis.
• Known brain metastases unless asymptomatic and not requiring steroids for at least 2 weeks prior to the first dose of any study drug administration.
• Active systemic autoimmune disease or any other condition that requires, or is anticipated to require, systemic treatment with steroids or other systemic immunosuppressive agents, or participants who have received such agents within 4 weeks of leukapheresis and ML261 administration (further details provided in protocol body).
• Evidence of interstitial lung disease (such as idiopathic pulmonary fibrosis) or active pneumonitis of any etiology requiring treatment.

Sponsors & Collaborators

• Moonlight Bio, Inc: lead

Study Sites (5)

Hackensack University Medical Center

Hackensack, New Jersey, 07601, United States

Location

NYU Langone Health

New York, New York, 10016, United States

Location

Sarah Cannon Research Institute (SCRI)

Nashville, Tennessee, 37203, United States

Location

UT Southwestern Medical Center

Dallas, Texas, 75235, United States

Location

MD Anderson Cancer Center

Houston, Texas, 77030, United States

Location

MeSH Terms

Conditions

Small Cell Lung Carcinoma; Carcinoma, Neuroendocrine

Condition Hierarchy (Ancestors)

Carcinoma, Bronchogenic; Bronchial Neoplasms; Lung Neoplasms; Respiratory Tract Neoplasms; Thoracic Neoplasms; Neoplasms by Site; Neoplasms; Lung Diseases; Respiratory Tract Diseases; Neuroendocrine Tumors; Neuroectodermal Tumors; Neoplasms, Germ Cell and Embryonal; Neoplasms by Histologic Type; Adenocarcinoma; Carcinoma; Neoplasms, Glandular and Epithelial; Neoplasms, Nerve Tissue

Central Study Contacts

Moonlight Bio Clinical Team

CONTACT

206-647-6168; MLTrials@moonlightbio.us

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Drug

Study Record Dates

• First Submitted: March 13, 2026
• First Posted: March 23, 2026
• Study Start: June 1, 2026
• Primary Completion (Estimated): March 1, 2028
• Study Completion (Estimated): August 1, 2030
• Last Updated: June 25, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

US (5)