A Phase 3 interventional study of Experimental group : Cabometyx ® 40mg/m2/day (Max: 60mg/day) , Treatment schedule : Daily**, day 1-28 during 4 weeks (ie. 1 cycle) during 12 cycles in Osteosarcoma, Pediatric Osteosarcoma and Osteosarcoma in Children, sponsored by Gustave Roussy, Cancer Campus, Grand Paris. Recruiting at 77 sites in 8 countries. Open to participants aged 4 Years and older. Per ClinicalTrials.gov, last updated 2026-10-13.
Sponsored by Gustave Roussy, Cancer Campus, Grand Paris · Phase 3, Interventional, and Treatment
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.
446 studies on the registry are indexed under Osteosarcoma; 117 are open to participants now.
This study's planned enrollment of 530 is above the median of 41 across 330 interventional studies indexed under Osteosarcoma.
Browse Osteosarcoma studies →Gustave Roussy, Cancer Campus, Grand Paris is the lead sponsor of 244 studies on the registry; 66 are open to participants now.
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REGISTRATION in FOSTER-Evolving study platfom, Part-1:
Inclusion Criteria :
Exclusion Criteria:
1. Low-grade osteosarcoma, parosteal or periosteal osteosarcoma, small cell osteosarcoma
FOR FOSTER-CabOS RANDOMISATION (part-2) :
Screening laboratory values must meet the following criteria (according to CTCAE v5) and should be obtained within 7 days prior to randomisation
Cabozantinib orally, 40 mg/m2/day (Max=60mg/day) x1/day, administered for 12 cycles of 28 days each maximum
Drug: Experimental group : Cabometyx ® 40mg/m2/day (Max: 60mg/day) , Treatment schedule : Daily**, day 1-28 during 4 weeks (ie. 1 cycle) during 12 cycles
Best Supportive Care according to the country
Drug page: Cabozantinib
The intervention evaluated in FOSTER-CabOS is a maintenance treatment strategy using cabozantinib administered after completion of standard first-line therapy for newly diagnosed high-grade osteosarcoma. Unlike induction or salvage treatments, this intervention is introduced in patients without disease progression following standard treatment and aims to prevent or delay relapse. The study specifically evaluates the added value of 12 cycles of cabozantinib as maintenance therapy in a broad population of paediatric and adult osteosarcoma patients. This distinguishes the intervention from other osteosarcoma studies that typically focus on chemotherapy intensification, relapse treatment, or biomarker-selected population.
Part 1 of the study (Registration at diagnosis) : event-free survival (EFS)rate of the cohort overall different treatment sequences (First line of treatment) during 3 years .
EFS: time from diagnosis to the first occurrence of progression/relapse (local, regional, or distant), second primary malignancy, or death from any cause; events per investigator assessment with central review when available. Patients without an event are censored at the date of last follow-up.
Time frame: 3 years
Specific to FOSTER-CabOS (part-2), the first randomization question of the FOSTER evolving study platform: EFS of cabozantinib compared to best supportive care (BSC) as maintenance therapy after first-line chemotherapy
Considering EFS improvement in one or both of the following datasets : * patients in complete remission (CR) at the end of first-line therapy (stratum-1), * the whole randomised dataset, including patients with residual persistent stable disease after first-line treatment (non-resectable primary tumour, or metastatic disease not be completely resected), i.e. strata 1 and 2. Event-free survival (EFS): time from randomisation to first recurrence or progression (local, regional or distant) based on central review evaluation, or death from any cause. A patient without an event is considered censored at his or her last follow-up date.
Time frame: through study completion, an average of 8 year
FOSTER evolving study platform (part 1): compliance with the first line conventional chemotherapy.
first line chemotherapy treatment delivery (dose intensity, delays, reductions, early discontinuation, reasons),
Time frame: 1 year
FOSTER evolving study platform (part 1): proportion of EFS and alive patients after the first line conventional chemotherapy.
EFS: time from diagnosis to the first occurrence of progression/relapse (local, regional, or distant), second primary malignancy, or death from any cause; events per investigator assessment with central review when available. Patients without an event are censored at the date of last follow-up.
Time frame: 1 year
FOSTER evolving study platform (part 1): the 3-year overall survival (OS) rate of the cohort overall, considering all treatment sequences.
Overall survival (OS): time from diagnosis to death from any cause
Time frame: from diagnosis to 3 years
FOSTER evolving study platform (part 1): the 5-year event-free survival (EFS) rate of the cohort overall, considering all treatment sequences.
EFS: time from diagnosis to the first occurrence of progression/relapse (local, regional, or distant), second primary malignancy, or death from any cause; events per investigator assessment with central review when available. Patients without an event are censored at the date of last follow-up.
Time frame: from diagnosis to 5 years
FOSTER evolving study platform (part 1) : adverse events under treatment sequences
Adverse events: incidence of treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and treatment-related mortality during induction.
Time frame: from diagnosis to 8 years
FOSTER evolving study platform (part 1): quality of life (QoL) using validated instruments, including: EORTC QLQ C30,
Quality of life and functional outcome: QoL assessed by EORTC QLQ-C30
Time frame: from diagnosis to 8 years
FOSTER Evolving study Platform (part 1): prognostic value of clinical and biological factors, including but not limited to the G1/G2 signature determined at diagnosis, assessed by RNA sequencing or by simpler methods (e.g., IHC)
Prognostic factors: association of clinical and biological variables (including G1/G2 signature at diagnosis) with OS and EFS via multivariable-adjusted Cox models.
Time frame: at diagnosis
Specific for FOSTER-CabOS randomised trial (part-2): Adverse events (AE) of grade 3+, for patient under Cabozantinib, combined with mifamurtide
* Adverse events (AE), a real-time reporting of any AE of grade 3+ is planned during the first 8 weeks in the first 20 patients receiving mifamurtide. * The occurrence of cabozantinib related toxicities grade ≥3 within the first three months of treatment according to cabozantinib exposure.
Time frame: from beginnning of Cabozantinib to 3 months after.
Specific for FOSTER-CabOS randomised trial (part-2): Q-TWiST and the net treatment benefit,
Quality-adjusted time without symptoms of disease or toxicity (Quality-adjusted Time Without Symptoms of disease recurrence or Toxicity (Q-TWiST)) computed from survival times (OS and Event Free Survival (EFS) duration) and adverse events data (duration of time spent with a severe-AE before progression/recurrence)
Time frame: from the beginning of the part 2 to 8 years maximum
Specific for FOSTER-CabOS randomised trial (part-2): compliance of Cabozantinib
Feasibility and compliance: Cabozantinib compliance (dose taken)
Time frame: from the beginning of cabozantinib to 12 cycles (of 28 days)
Specific for FOSTER-CabOS randomised trial (part-2): Event-Free Survival (EFS) according to clinical, radiological and biological factors, and treatment-by-subgroup interaction analyses assessing whether the effect of cabozantinib on EFS
i.e to define whether the treatment effect of Cabozantinib on EFS differs between subgroups of patients (disease status; histological response of the primary tumour; biological subgroups in particular G1/G2 diagnostic RNAseq signature; type of first line chemotherapy; use of mifamurtide; age, metastatic status at diagnosis) Note that the determination of G1/G2 signature requires the implementation of biology sample collections of the primary tumour.
Time frame: at diagnostic to 12 cycles of cabozantinib (after randomization = 1 year)
Specific for FOSTER-CabOS randomised trial (part-2): IGF1 (Insuline-Like Growth Factor 1)
in paediatric patients \< 18 years with Tanner stage 1 to 2 at inclusion To evaluate whether cabozantinib affects the longitudinal growth in Pediatric population .
Time frame: at baseline in part 2, End of treatment at 12 cycles, and every year until 8 years
Specific for FOSTER-CabOS randomised trial (part-2): wound healing
Vancouver Scare Scale: , range 0-13. Higher scores indicate worse scar characteristics and therefore a poorer outcome.
Time frame: at baseline in part 2, every 3 months during the 12 cycles of cabozantinib, and End of Treatment (1 year).
FOSTER evolving study platform (part 1): quality of life (QoL) using validated instruments, including: PedQl,
Health- related QoL in patients \<18 uears will be assessed using the Pediatric Quality of Life Inventory (PedsQL) Generic Core Scales
Time frame: Baseline, every 3 months until 8 years
quality of life (QoL) using validated instruments, including: Functional outcome assessed by the Toronto Extremity Salvage Score (TESS).
The TESS is a patient-reported outcome measure developed to assess functional outcomes in patients who have undergone surgery, typically for bone or soft tissue tumors. It is used to evaluate the patient's ability to perform activities of daily living following surgery, focusing on areas such as mobility, self-care, and other daily activities.
Time frame: from diagnosis to every 3 months during 8 years
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Cabozantinib
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