In this study Drug-eluting microbeads (DEB) loaded with Doxorubicin will be delivered into the target Desmoid Fibromatoses (DF) tissue via selective arterial embolization by angiographic technique. The objective of the study is to demonstrate the safety and efficacy of this treatment.

Desmoid Fibromatoses (DF) are locally aggressive lesions associated with substantial morbidity and potentially mortality, due to invasion of adjacent neurovascular structures and vital organs. They have no potential for metastasis. Histologically, they are characterised by mature fibroblasts within a matrix of abundant fibrous stroma. While 5-15% of cases are seen in patients with Familial Adenomatous Polyposis (FAP) syndrome, the vast majority arise sporadically.

The etiology of Desmoids remains poorly understood and the therapeutic approaches in their management remain very diverse. For resectable lesions, surgery is recommended but reported cure rates range broadly from 12-80%. Systemic treatments range from non-steroidal anti-inflammatories and anti-estrogenic therapy to targeted tyrosine kinase inhibitors and cytotoxic chemotherapy, most commonly methotrexate, vinblastine and doxorubicin.

Doxorubicin is an anthracycline with demonstrated efficacy in treating desmoids at systemic IV doses of 50- 75mg/m2 over 3-4 week cycles. Extended use is limited by dose - dependent cardiotoxicity which can be seen in up to 36% of patients receiving doses in excess of 550mg/m2. Delayed cardiotoxicity is particularly common and less predictable among pediatric cancer survivors.

Selective trans-arterial chemo-embolization (TACE) is a method to achieve high tissue drug concentration with minimal systemic toxicity. Historically, this has been achieved by mixing doxorubicin with embolic agents such as lipiodol or gelatin sponge in the treatment of hepatocellular carcinoma (HCC).

Drug-eluting microbeads (DEB) ionically loaded with doxorubicin have shown sustained release in TACE target tissues with substantially lower serum drug concentrations when compared to lipiodol TACE.

The present study utilizes DEB's loaded with Doxorubicin delivered into the target DF tissue via selective arterial embolization by angiographic technique. This study follows a successful feasibility study.

Inclusion Criteria:

1. Age 3-80 years.

2. Histologically confirmed diagnosis of Desmoids Fibromatosis.

3. After at least one systemic treatment line. Standard first line systemic treatment may include: Methotrexate, Vinblastine, Doxorubicin, Liposomal Doxorubicin (Doxil), NSAIDS or hormonal treatment. If first line treatment is renounced, this treatment decision must be documented. Considering the trend of avoiding surgical treatment, the documentation must include that the treatment decision is not associated to the resectability of the tumor.

4. Karnofsky performance status (PS)>50% for patients older than 16 years or Lansky PS >50% for patients under 16 years.

5. At least one measurable lesion, with a long diameter of at least 30mm, with an anatomical location accessible for endovascular treatment.

6. T2 signal increase on MRI.

7. No evidence of prior treatment toxicity, adequate washout period after prior treatment:

   • 14 days after myelosuppressive chemotherapy treatment.
   • 7 days after GCSF (Granulocyte colony-stimulating factor), 14 days after Neulastim.
   • 7 days after targeted/biologic treatment.

8. Female patients of childbearing potential must be willing to use an adequate method of contraception (hormonal, barrier or abstinence) for the treatment period and up to 90 days after the treatment completion.

9. Willing and able to provide written informed consent for the trial.

Exclusion Criteria:

1. Participation in another interventional study.
2. Congestive heart failure, characterised by LVEF (Left Ventricular Ejection Fraction) < 50% or Shortening fracture < 27%.
3. Previous treatment with anthracycline of a accumulative dose of more than 360 mg/m2.
4. History of allergic reaction attributed to Doxil or doxorubicin treatment.
5. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure (New York Heart Association Class III or IV), cardiac arrhythmia, or psychiatric illness, social situations that would limit compliance with study requirements.