A Study to Assess Safety and Efficacy of SOT106 in Patients With LRRC15-positive Advanced Unresectable or Metastatic Osteosarcoma or Soft Tissue Sarcoma

NCT07801222 | Not Yet Recruiting Phase 1 DMC FDA Drug

• 3 other identifiers: 106S012026-526231-19-00ADCLARA-01
• Study Type: interventional
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

SOT106 is a special cancer medicine designed to find and kill certain cancer cells that carry a marker called LRRC15, while causing less harm to healthy cells. The study consists of two parts, Part A and Part B. The goal of Part A is to collect information about SOT106, understand its effects, and see whether it is safe and well tolerated at different dose levels. Part B of the study collects information on which of the two selected safe dose levels chosen in Part A gives the best balance between benefit and risk.

Conditions

Osteosarcoma Metastatic; Soft Tissue Sarcoma (STS); Osteosarcoma, Advanced

Keywords

Dose escalation; Osteosarcoma; Soft Tissue Sarcoma (STS); Dose optimization

Outcome Measures

Primary Outcomes (4)

• Part A: Maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of SOT106

  MTD will be selected as guided by the time to-event Bayesian optimal interval (TITEBOIN) design. The RP2D will be selected based on integrated evaluation of the totality of clinical and preclinical data, for all dose levels tested.

  At the end of Cycle 1 (one cycle is 21 days)

• Part B: Optimal dose of SOT106 for subsequent clinical trials

  Assessment of the safety and tolerability of two recommended doses under evaluation for dose optimization (RDOs) of SOT106 by evaluation of the occurrence of SOT106 related TEAEs, serious TEAEs, TEAEs leading to premature discontinuation of SOT106, deaths, and clinical laboratory test abnormalities of grade 3 or higher according to NCI CTCAE Version 6.0

  Cycle 1 Day 1 up to 30 days after the last dose (each cycle is 21 days)

• Part B: Objective Response Rate (ORR) of SOT106

  Percentage of participants who achieve a Best Overall Response of Complete Response (CR) or Partial Response (PR) according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

  From Day 1 of Cycle 1 (one cycle is 21 days) until disease progression, initiation of new anticancer therapy, withdrawal of consent, or study discontinuation, whichever comes first, to be assessed up to approximately 10 months

• Part B: Duration of Response (DoR) of SOT106

  The time from the first documentation of objective response (CR or PR) to the first documented date of progressive disease (PD) according to RECIST v1.1.

  From the date of first documented objective response until disease progression, initiation of new anticancer therapy, withdrawal of consent, or study discontinuation, whichever comes first, assessed up to approximately 10 months.

Secondary Outcomes (13)

• Part A: Safety and Tolerability of SOT106

  From Cycle 1 Day 1 (one cycle is 21 days) assessed for approximately 17 months

• Part A: Characterization of maximum concentration (Cmax)

  From Cycle 1 Day 1 up to approximately 17 months (each cycle is 21 days)

• Part A: Characterization of time to maximum concentration (Tmax)

  From Cycle 1 Day 1 up to approximately 17 months (each cycle is 21 days)

• Part A: Characterization of area under the curve

  From Cycle 1 Day 1 up to approximately 17 months (each cycle is 21 days)

• Part A: Preliminary anticancer activity of SOT106

  From Day 1 of Cycle 1 (one cycle is 21 days) until disease progression, initiation of new anticancer therapy, withdrawal of consent, or study discontinuation, whichever comes first, to be assessed up to approximately 17 months

Study Arms (6)

SOT106 (Part A) dose level 1

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

SOT106 (Part A) dose level 2

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

SOT106 (Part A) dose level 3

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

SOT106 (Part A) dose level 4

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

SOT106 (Part B) recommended dose for optimization 1

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

SOT106 (Part B) recommended dose for optimization 2

EXPERIMENTAL

Patients with LRRC15-positive advanced unresectable or metastatic osteosarcoma and soft tissue sarcoma treated with SOT106 given once every 21 days via the IV route over 45 (±15) minutes.

Biological: SOT106

Interventions

SOT106 BIOLOGICAL

SOT106 is a LRRC15-directed monoclonal antibody conjugated to a linker-payload, Monomethyl auristatin E

SOT106 (Part A) dose level 1; SOT106 (Part A) dose level 2; SOT106 (Part A) dose level 3; SOT106 (Part A) dose level 4; SOT106 (Part B) recommended dose for optimization 1; SOT106 (Part B) recommended dose for optimization 2

Eligibility Criteria

• Age: 12 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• ≥18 years of age and body weight of ≥30 kg on the day of signing the prescreening ICF
• In the US after dose levels 1 and 2 have been declared safe (following DEC review of the safety and PK data from the first two adult dose levels), participants aged ≥12 years on the day of signing the prescreening ICF may be enrolled from dose level 3 onwards
• In the EU participants aged ≥12 years on the day of signing the prescreening ICF may be enrolled in backfilling cohorts once dose level 3 has been cleared in adults, following DEC review of safety, PK and efficacy data. In addition, preliminary signs of efficacy should have been observed in adults, based on the investigator's judgment.
• Participants ≥ 18 years of age are able to understand, sign, and provide written informed consent to participate in the trial. For participants under 18 years of age, their legal representative must provide a written informed consent. Participants aged 12 to 17 must be willing and able to provide a written assent.
• Estimated life expectancy ≥3 months as assessed by the investigator
• An appropriate candidate for experimental therapy as assessed by the investigator
• Availability of adequate tumor tissue from an archival biopsy (FFPE block or unstained slides) or willingness to undergo a fresh tumor biopsy. A minimum of ≥1% (1+) of cells must exhibit LRRC15 expression with an intensity of at least 1+ by IHC.
• Note: Tumor samples will be sent to a central laboratory for LRRC15 expression analysis.
• Agrees not to participate in other interventional clinical trials while enrolled in the present trial (with the exception of survival follow-up period). For participants under 18 years of age, their legal representative must agree that they will not participate in other interventional clinical trials while enrolled in the present trial (with the exception of survival follow-up period).
• Absolute neutrophil count ≥1.5×109/L, platelets ≥100×109/L, hemoglobin ≥9 g/dL
• Renal function:
• For participants ≥ 18 years of age: creatinine clearance ≥ 60 mL/min calculated by Cockcroft-Gault formula
• For adolescent participants (aged 12-17 years): estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m², calculated using the Bedside Schwartz formula
• Bilirubin ≤1.5× upper limits of normal (ULN), ALT and AST ≤2.5×ULN; in case of liver involvement: AST and ALT ≤5×ULN.
• Participants with a documented history of Gilbert syndrome may be eligible if:

You may not qualify if:

• Received radiation therapy ≤14 days before day 1 of cycle 1 or not recovered to grade ≤1 from treatment-related side effects
• Any prior systemic therapy for metastatic cancer other than osteosarcoma and STS; exception: stable disease under hormonal treatment for prostate cancer, stable disease under hormonal treatment for breast cancer; radiochemotherapy is allowed if such treatment is completed at least 4 weeks prior to day 1 of cycle 1; participants must have recovered to grade ≤1 from all side effects (exception: alopecia). Participants must not receive any concurrent antitumor therapy while participating in the trial. In exceptional circumstances where urgent palliative radiotherapy to symptomatic non-target lesions is clinically indicated, the case must be reviewed with the Principal Investigator and the intervention must receive prior approval from the sponsor.
• Vaccination with a live or live-attenuated vaccine within 30 days prior to the first dose of trial interventions; the full series (e.g., both doses of a two-dose vaccination series) should be completed prior to dosing if feasible.
• Time since last transfusion of red blood cells ≤14 days before day 1 of cycle 1
• Concomitant use of strong CYP3A4 inhibitors or P-gp inhibitors without an adequate washout period of 7 days or 5 half-lives, whichever is longer, prior to the first SOT106 administration
• Severe preexisting medical conditions as per judgment of the investigator
• History of interstitial pneumonitis or pulmonary fibrosis
• Symptomatic central nervous system malignancy. Participants with asymptomatic or treated central nervous system metastases may be eligible if they are not treated with corticosteroids or anticonvulsants and the disease is stable for at least 60 days.
• Peripheral sensory neuropathy grade ≥2
• Active infection requiring systemic therapy that is not clinically controlled before the signature of the prescreening ICF
• Known symptomatic HIV positive, symptomatic active HBV, or symptomatic active HCV
• Note:
• Participants with HIV will be eligible if:
• CD4+ T-cell counts ≥350 cells/μL
• they have no history of AIDS-defining opportunistic infections

Sponsors & Collaborators

• SOTIO Biotech a.s.: lead

Study Sites (1)

Arensia Exploratory Medicine Research Unit, Institute of Oncology

Chisinau, Moldova

Location

MeSH Terms

Conditions

Sarcoma; Osteosarcoma

Condition Hierarchy (Ancestors)

Neoplasms, Connective and Soft Tissue; Neoplasms by Histologic Type; Neoplasms; Neoplasms, Bone Tissue; Neoplasms, Connective Tissue

Study Officials

• Silvia Stacchiotti, M.D.

  S.C. Oncologia Medica 2, Tumori Mesenchimali e Rari, Fondazione IRCCS, Istituto Nazionale dei Tumori

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Richard Kapsa

CONTACT

(+420) 2241 74448; kapsa@sotio.com

Study Design

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

Model Details: Part A: 4 cohorts, dose-escalation, Time-to-Event Bayesian Optimal Interval Design (TITE-BOIN) trial. Part B: Randomized, open-label dose optimization trial

Study Record Dates

• First Submitted: August 21, 2026
• First Posted: September 3, 2026
• Study Start: September 30, 2026
• Primary Completion (Estimated): January 19, 2029
• Study Completion (Estimated): May 21, 2030
• Last Updated: September 3, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

MO (1)