Relapsed / Refractory OsteosarcomaPhase 1/2NCT07357519
Lu-TARGO (177Lu-TARGeted Osteosarcoma Therapy)
A Phase 1/2 study testing LNTH2403 Phase 1 dose and Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D). in people with Relapsed / Refractory Osteosarcoma, run by Lantheus Medical Imaging at 2 sites in United States.
Trial summary
This is a multi-center, non-randomized, open-label, dosimetry and dose-escalation, cohort-expansion study of LNTH-2403 administered to subjects with relapsed / refractory (R/R) osteosarcoma. This study consists of 2 phases: (1) a dosimetry and dose escalation phase; and (2) a cohort expansion phase. Read more about this study
- Who is it for?
- Ages 12 years and older
- Conditions the study is for
- Relapsed / Refractory Osteosarcoma
- What is being tested?
- LNTH2403 Phase 1 dose and Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D).
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 55 participants
- Where
- 2 sitesUnited States
- Study dates
- 3 Feb 2026to May 2032
- Phase
- Phase 1/2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
None listed.
Who cannot join
- Participants meeting any of the following criteria will be excluded from the study
- Known allergies, hypersensitivity, or intolerance to LNTH-2403 and/or its excipients
- Prior or ongoing clinically significant illness, medical condition, surgical history, physical finding, or laboratory abnormality that, in the investigator's opinion, may affect the participant's safety, compliance with the study, or otherwise impair the assessment of study results
- Concurrent treatment with any other anti-neoplastic agents, including localized radiation therapy
- Known active infection
- Participation in an interventional study of another investigational agent
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- Prior therapies or diagnostics
- Active prior or concurrent malignancy: immunoglobulin),
- Known active liver disease from any cause, Hepatitis A Virus
- Known to be human immunodeficiency virus (HIV) positive
- Clinically relevant cardiovascular disease
- Receipt of live vaccine within the 30 days prior to the first dose o
- A female participant who is pregnant or breastfeeding
- Major surgical procedure within 28 days of the first dose of LNTH-2403.
- Participant is unwilling or unable to comply with the scheduled visits, drug administration plan, laboratory tests, or other study procedures and study restrictions
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States2 sites, 2 recruiting
- Recruiting
Dana Farber Cancer Institute
Boston, Massachusetts, 02115
Sarcoma Program Research Nurse, 877-DF-TRIAL (877-388-7425)
- Recruiting
UCLA
Los Angeles, California, 90095
Gregory Ellis, (424) 320-1853, GEllis@mednet.ucla.edu
About this study
Official title: A Phase 1/2, Multi-Center, Open-Label Study to Evaluate the Safety, Tolerability, Pharmacokinetics, -Radiation Dosimetry, and Preliminary Anti-Neoplastic Activity of LNTH-2403, a LRRC15-targeted 177Lutetium-labeled Monoclonal Antibody, in Participants With Relapsed / Refractory Osteosarcoma
This is a multi-center, non-randomized, open-label, dosimetry and dose-escalation, cohort-expansion study of LNTH-2403 administered to subjects with relapsed / refractory (R/R) osteosarcoma. This study consists of 2 phases: (1) a dosimetry and dose escalation phase; and (2) a cohort expansion phase.
- Conditions
- Relapsed / Refractory Osteosarcoma
- Being tested
- LNTH2403 Phase 1 dose, Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D).
- Medical subject headings
- Osteosarcoma
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LNTH2403 Phase 1 doseDrug
LNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data.
Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D).Drug
Once the RP2D is selected, phase 2 will commence
| Study group | Role | What they receive |
|---|---|---|
| Phase 1- Escalating doses of LNTH-2403 administered once every 8 weeks | Experimental | Phase 1 will evaluate escalating doses of LNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data. Receives: Drug: LNTH2403 Phase 1 dose |
| Phase 2 will evaluate LNTH-2403 as a single agent at the recommended phase 2 dose | Experimental | Phase 2 will evaluate LNTH-2403 as a single agent in participants with R/R osteosarcoma at the recommended phase 2 dose (RP2D). Receives: Drug: Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D). |
What is being measured
The primary outcome is the main question the study is designed to answer.
To identify the maximum tolerated dose (MTD) of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Incidence of DLTs during the first 8 weeks (DLT evaluation window) after the first dose of LNTH-2403
Measured: From enrollment to the end of treatment at 8 weeks
To evaluate the safety and tolerability profile of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Type, frequency, severity, timing, and relationship to LNTH-2403 of all Treatment-emergent adverse event, (TEAEs) and Serious adverse events, (SAEs)
Measured: From enrollment to the end of treatment at 8 weeks
To assess the preliminary anti-neoplastic activity of LNTH-2403 in participants with R/R osteosarcoma (Ph2)
Event-Free Survival (EFS) at 4 months
Measured: From enrollment to Event-Free Survival (EFS) at 4 months
Secondary outcomes (2)
To assess the preliminary anti-neoplastic activity of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Event-Free Survival (EFS) at 8 weeks
Measured: 8 weeks
To describe the safety and tolerability profile of LNTH-2403 in participants with R/R osteosarcoma (Ph2)
Type, frequency, severity, timing, and relationship to LNTH-2403 of any TEAEs and SAEs
Measured: 4 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Jan 2026
- Study start3 Feb 2026
- Primary completionAug 2027 (estimated)
- Study completionMay 2032 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Relapsed / Refractory OsteosarcomaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1/2
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Single group
- Model description
- Phase 1 will evaluate escalating doses of LNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data. Phase 2 will evaluate LNTH-2403 as a single agent in participants with R/R osteosarcoma at the recommended phase 2 dose (RP2D).
- Masking
- None (open label)
- Enrolment
- 55 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Lantheus Medical Imaging
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07357519
- Sponsor's protocol ID
- LNTH2403-1301
- Status last verified
- Jan 2026
- First submitted
- 14 Jan 2026
- Last updated
- 1 May 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 1 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1/2, Multi-Center, Open-Label Study to Evaluate the Safety, Tolerability, Pharmacokinetics, -Radiation Dosimetry, and Preliminary Anti-Neoplastic Activity of LNTH-2403, a LRRC15-targeted 177Lutetium-labeled Monoclonal Antibody, in Participants With Relapsed / Refractory Osteosarcoma
- ClinicalTrials.gov ID
- NCT07357519
- Acronym / sponsor ID
- LNTH2403-1301
- Conditions
- Relapsed / Refractory Osteosarcoma
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 55 participants (estimated)
- Lead sponsor
- Lantheus Medical ImagingIndustry (pharma, biotech, devices)
- Study start
- 3 Feb 2026 (actual)
- Primary completion
- Aug 2027 (estimated)
- Study completion
- May 2032 (estimated)
- First posted
- 22 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a multi-center, non-randomized, open-label, dosimetry and dose-escalation, cohort-expansion study of LNTH-2403 administered to subjects with relapsed / refractory (R/R) osteosarcoma. This study consists of 2 phases: (1) a dosimetry and dose escalation phase; and (2) a cohort expansion phase.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Phase 1 will evaluate escalating doses of LNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data. Phase 2 will evaluate LNTH-2403 as a single agent in participants with R/R osteosarcoma at the recommended phase 2 dose (RP2D).
| Arm | Type | Receives |
|---|---|---|
| Phase 1- Escalating doses of LNTH-2403 administered once every 8 weeks | Experimental | Drug: LNTH2403 Phase 1 dosePhase 1 will evaluate escalating doses of LNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data. |
| Phase 2 will evaluate LNTH-2403 as a single agent at the recommended phase 2 dose | Experimental | Drug: Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D).Phase 2 will evaluate LNTH-2403 as a single agent in participants with R/R osteosarcoma at the recommended phase 2 dose (RP2D). |
Who may qualify
- Ages
- 12 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (0 listed)
Key exclusion criteria (15 listed)
- Participants meeting any of the following criteria will be excluded from the study
- Known allergies, hypersensitivity, or intolerance to LNTH-2403 and/or its excipients
- Prior or ongoing clinically significant illness, medical condition, surgical history, physical finding, or laboratory abnormality that, in the investigator's opinion, may affect the participant's safety, compliance with the study, or otherwise impair the assessment of study results
- Concurrent treatment with any other anti-neoplastic agents, including localized radiation therapy
- Known active infection
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| LNTH2403 Phase 1 doseLNTH-2403 administered once every 8 weeks, with the potential to explore other dosing schedules based on observed radiation dosimetry and PK parameters and safety and tolerability data. | Drug | Phase 1- Escalating doses of LNTH-2403 administered once every 8 weeks |
| Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D).Once the RP2D is selected, phase 2 will commence | Drug | Phase 2 will evaluate LNTH-2403 as a single agent at the recommended phase 2 dose |
Primary outcome
To identify the maximum tolerated dose (MTD) of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Time frame: From enrollment to the end of treatment at 8 weeks
Incidence of DLTs during the first 8 weeks (DLT evaluation window) after the first dose of LNTH-2403
To evaluate the safety and tolerability profile of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Time frame: From enrollment to the end of treatment at 8 weeks
Type, frequency, severity, timing, and relationship to LNTH-2403 of all Treatment-emergent adverse event, (TEAEs) and Serious adverse events, (SAEs)
To assess the preliminary anti-neoplastic activity of LNTH-2403 in participants with R/R osteosarcoma (Ph2)
Time frame: From enrollment to Event-Free Survival (EFS) at 4 months
Event-Free Survival (EFS) at 4 months
2 secondary outcomes
To assess the preliminary anti-neoplastic activity of LNTH-2403 in participants with R/R osteosarcoma (Ph1)
Time frame: 8 weeks
To describe the safety and tolerability profile of LNTH-2403 in participants with R/R osteosarcoma (Ph2)
Time frame: 4 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 May 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing LNTH2403 Phase 1 dose and Phase 2; LNTH2403 a single agent recommended phase 2 dose (RP2D). in people with Relapsed / Refractory Osteosarcoma, run by Lantheus Medical Imaging at 2 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 0 inclusion and 15 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 1 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Kerri Sforzo (978-671-8886, clinicaltrials@lantheus.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To identify the maximum tolerated dose (MTD) of LNTH-2403 in participants with R/R osteosarcoma (Ph1) (time frame: From enrollment to the end of treatment at 8 weeks). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 May 2026.