(P 144) EXPLORATORY ANALYSIS OF 68GA-FAPI-46 PET-CT IN SOFT TISSUE SARCOMA

Author(s)

Valentina Fausti, MD

Medical Doctor
Clinical and Experimental Oncology, Immunotherapy, Rare Cancers and Biological Resource Center, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola, Italy
Meldola, Emilia-Romagna, Italy

Co-Author(s)

VG

Virginia Ghini, MD

Irst - Meldola
Meldola, Emilia-Romagna, Italy
Laura Ridolfi, MD

Chief of Immunotherapy and Rare Tumor Unit
IRCCS Istituto Romagnolo per lo Studio dei Tumori "Dino Amadori"
Meldola, Emilia-Romagna, Italy
LG

Lorena Gurrieri, MD

Medical Doctor
Clinical and Experimental Oncology, Immunotherapy, Rare Cancers and Biological Resource Center, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola, Italy
Meldola, Emilia-Romagna, Italy
NR

Nada Riva, MD

Medical Doctor
Clinical and Experimental Oncology, Immunotherapy, Rare Cancers and Biological Resource Center, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori"
Meldola, Emilia-Romagna, Italy
NR

Nicoletta Ranallo, MD (she/her/hers)

Physician
Irst
Meldola, Emilia-Romagna, Italy
sC

sebastiano Calpona, N/A, MD

Irst
Meldola, Emilia-Romagna, Italy
fD

francesco De Rosa, MD

Irst
Meldola, Emilia-Romagna, Italy
LF

Lorenzo Fantini, MD

IRST - Meldola
Meldola, Emilia-Romagna, Italy
FM

Federica Matteucci, MD

IRST - Meldola
Meldola, Emilia-Romagna, Italy
PC

Paola Caroli, MD

IRST - Meldola
Meldola, Emilia-Romagna, Italy

Objective: Soft-tissue sarcomas highly express fibroblast activation protein (FAP) on tumor cells and associated activated fibroblasts. Thus, the expression of FAP on diferent STS needs to be identifed. The primary objective of this study is to evaluate the sensitivity of 68Ga-FAPI-46 PET/CT in patients with soft tissue sarcoma.

Methods: Currently, we enrolled six patients affected by soft tissue sarcoma (2 females and 4 males; median age=68.3 years old). All patients were diagnosed with STS. Five patients underwent surgery of the primary tumor and need subsequent lines of chemotherapy in the metastatic assesment. One patient is affected by localized desmoid fibromatosis, newly discovered.

Results: Diagnostic 68Ga-FAPI-46 PET/CT was performed in 6 patients, and positive findings were observed in 4 of them (retroperitoneal dedifferentiated liposarcoma, high grade myxoid liposarcoma, desmoid fibromatosis, solitary fibrous tumor). The patient with retroperitoneal well differentiated liposarcoma showed un uncertain uptake, while the polmonary Leiomyosarcoma was negative.

Conclusion: FAP is overexpressed in cancer-associated fbroblasts (CAFs) in the stroma of more than 90% of epithelial carcinomas and many subtypes of STS (e.g., fbrosarcoma, malignant fbrous histiocytoma, and liposarcoma). FAP plays a pivotal role in tumor microenvironment, including reduced levels of anti-angiogenic factors, elevated levels of transforming growth factor β, and afected matrix processing enzymes.
Preliminary data about the sensitivity of 68Ga-FAPI-46 PET/CT in detection patients with soft tissue sarcoma, seems promising, in particolar for patient with desmoid fibromatosis. In addition to diagnostic imaging, FAP is also considered as a promising target for delivering therapeutic nuclide. Several FAP-targeting therapies are currently in development, including small molecule inhibitors, monoclonal antibodies, and FAP-CAR-T cells. This may provide a new approach for recurrent STS to improve survival.