Cabozantinib after standard treatment for osteosarcoma, within a European research platform

Trial details

Who runs it

Gustave Roussy, Cancer Campus, Grand Paris

Trial code

NCT07871864

Record updated

26 October 2026

Original description

This clinical study is the initiative of the FOSTER (Fight OsteoSarcoma Through European Research) consortium and Gustave Roussy, which is the sponsor. Its aim is to evaluate the biology of tumour in greater depth by collecting samples of the tumour during the biopsy at diagnosis, and blood samples. This study is a platform study that evolves over time. This means that it allows for the evaluation of several treatments or therapeutic strategies within a single clinical trial, which can be modified and adapted over time.Read full original descriptionShow less

FOSTER Evolving Study Platform

This clinical study is the initiative of the FOSTER (Fight OsteoSarcoma Through European Research) consortium and Gustave Roussy, which is the sponsor. Its aim is to evaluate the biology of tumour in greater depth by collecting samples of the tumour during the biopsy at diagnosis, and blood samples. This study is a platform study that evolves over time. This means that it allows for the evaluation of several treatments or therapeutic strategies within a single clinical trial, which can be modified and adapted over time.

The FOSTER evolving study platform aim to implement a comprehensive strategy of clinical, biological, radiological, therapeutic integrated research from diagnosis to relapse, with the aim to improve survival of osteosarcoma patients of all age, through randomised therapeutic questions at different phase of treatment from diagnosis to relapse. The platform study makes it possible to evaluate several treatments for the same disease, on an ongoing basis, using a main protocol with adaptable arms.

The FOSTER-CabOS trial (part 2 of FOSTER study) is a European Phase III clinical study . It assesses the efficacy of cabozantinib, a tyrosine kinase inhibitor, as a maintenance therapy post-standard treatment in osteosarcoma patients. The trial is randomized against Best Supportive Care to determine the effectiveness of cabozantinib in improving event-free survival. This maintenance therapy aims to prevent relapse among patients who have already received standard treatment for osteosarcoma.

Inclusion: Newly diagnosed, biopsy-proven, high-grade osteosarcoma,; Patient considered medically fit to receive systemic treatment,; Planned systemic therapy according to national guidelines and age; Written informed consent from patients or for minor, from their parents/ legal representatives, before enrolment and any study-related procedure; Affiliation to a social insurance or equivalent regimen (if required in the country).

Exclusion: Recovery to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5 Grade 0 or 1 level or recovery to baseline health status preceding the prior treatment from any previous drug/procedure related toxicity (except alopecia, anaemia, and hypothyroidism); Interval between the last treatment either chemotherapy administration or surgical procedures or radiotherapy or thermoablation, (whichever occurred last) and the date of randomisation should be at least 4 weeks but no longer than 2 months; Adequately controlled blood pressure (BP) with or without antihypertensive medications: BP 95th percentile for sex, age and height/length at screening (as per NHLBI (National Heart, Lung and Blood Institute) guidelines) and no change in antihypertensive medications within 1 week prior to start of treatment (C1D1). Patients aged >18 years should have a BP ≤150/90 mmHg at screening and no change in antihypertensive therapy within 1 week prior to C1D1; Patients who are therapeutically treated with an agent such as warfarin or heparin/ Low-molecular-weight heparin (LMWH) will be allowed to participate provided that no prior evidence of underlying abnormality in coagulation parameters exists; Provision of dated and signed written informed consent from patients or for minor, from their parents/ legal representatives, for the randomised trial prior to any study specific procedures, sampling and analyses; Disease in complete remission or with residual persistent stable disease according to RECIST criteria before randomisation (please refer 7.3.4 for the definition of the residual persistent stable disease ); Adequate cardiac function: Left Ventricular Ejection Fraction (LVEF) ≥50% and/or fractional shortening (FS) >28% at baseline as determined by echocardiography or multigated acquisition (MUGA) scan (performed only if echocardiography is not feasible); Screening laboratory values must meet the following criteria (according to CTCAE v5) and should be obtained within 7 days prior to randomisation; Absolute neutrophil count ≥ 1 x 109/L; Platelets ≥ 100 x 109/L; Haemoglobin ≥ 8.0 g/dL (a hemoglobin of less than 8.0 g/dl is acceptable if it is corrected by growth factor or transfusion before C1D1); Serum creatinine ≤ 1.5 x ULN or based on age/gender. If serum creatinine is greater than maximum serum creatinine for age/gender as described, then creatinine clearance (or radioisotope Glomerular Filtration Rate (GFR)) must be >60 ml/min/1.73 m2; Urine dipstick < 2+ for proteinuria. Patients who have ≥2+ proteinuria on dipstick urinalysis should undergo a spot Protein/Creatinine ratio test that should be grade 2 (less or equal) per CTCAE v5.0; No clinical evidence of nephrotic syndrome; Alanine Aminotransferase/Aspartate Aminotransferase (ALT/AST) ≤ 2.5 x Upper limit of normal (ULN) in the absence of liver metastases or ≤ 5.0 x ULN in the presence of liver metastases; Total bilirubin ≤ 1.5 x ULN (except Gilbert Syndrome: < 3.0 mg/dL) or ≤ 5.0 x ULN in the presence of liver metastases; Alkaline phosphatase (PAL) ≤2.5 x ULN (≤5 x ULN in patient with liver involvement of their cancer). If Alkaline phosphatase > 2.5 ULN, Gamma-Glutamyl Transferase GGT tests must be performed; GGT < 1.5 x ULN; Lipase ≤1.5 x ULN; INR (International Normalized Ratio) /PTT (Partial Thromboplatin Time) ≤1.5 x ULN; Women of childbearing potential or young women of childbearing potential and who started their puberty (menarche) must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of Human Chorionic Gonadotropin (HCG)) done within 7 days prior to randomisation; Age ≥ 4 years old (when able to swallow tablet) ; no upper age limit; Effective methods of contraception should be used by male and female patients and their partners during therapy, and for at least 4 months after completing therapy. Because oral contraceptives might not be considered as "effective methods of contraception", they should be used together with another method, such as a barrier method, according to age and gynaecologist advice; Low-grade osteosarcoma, parosteal or periosteal osteosarcoma, small cell osteosarcoma; FOR FOSTER-CabOS RANDOMISATION (part-2) :; Patient with a histologically proven and confirmed high-grade osteosarcoma, according to the criteria described in the last World Health Organization (WHO) classification of Soft Tissue and Bone Tumours, after the exclusion of all potential differential diagnoses, either by local pathologists with expertise in bone sarcomas, or through centralized revision in a referral centre, according to national rules; First line systemic and local treatment of primary tumour (and metastasis when present) for localised or metastatic osteosarcoma must have been completed according to national guidelines (Mifamurtide is allowed according to centre's practices); Performance status < 2 for patient adult, or >70 using Karnofsky or Lansky performance scores; Patient fit to undergo protocol treatment and follow-up; Affiliation to a social insurance or equivalent regimen (if required in the country).

REGISTRATION in FOSTER-Evolving study platfom, Part-1:.

ClinicalTrials.gov NCT07871864