(P 328) REAL-LIFE EXPERIENCE OF PAZOPANIB IN PATIENTS WITH ADVANCED UTERINE LEIOMYOSARCOMA (U-LMS) FROM TWO REFERRAL ITALIAN CENTERS

Objective: U-LMS is a rare entity that needs to be referred to highly specialized sarcoma centers. The antiangiogenic agent Pazopanib is an oral multitargeted tirosine-kinase inhibitor already approved for soft tissue sarcoma with a Progression Free Survival (PFS) of 3 months in a phase III randomized study (PALETTE trial).

Methods: We retrospectively investigated all cases of patients with advanced U-LMS treated with Pazopanib at two Italian referral centers since September 2013. We reported the real word-data focusing on PFS, responses and complicated responses.

Results: From September 2013 to May 2023, 38 women with metastatic U-LMS received Pazopanib. The majority of patients were PS ECOG 0 or 1 (36/38); the median age was 52 years old (38-72 years old). Twenty-two/38 (58%) patients had more than 1 metastatic site with the most frequent one represented by lung (17/22). The median number of previous chemotherapy was 3 (range 2-5). All but 8 patients started Pazopanib at 800 mg daily; and ten of them (33%) required a dose reduction. Thirty-four patients were evaluable for response: 6/34 (18%) patients had a partial response, 12/34 (35%) patients had a SD. In the subgroup of patients treated at National Cancer Institute 7/26 (27%) patients had a response according to CHOI criteria. In the same subgroup, in 5/26 (19%) patients a complicated response was observed: in particular 1 pneumothorax, 2 intestinal perforation, 1 intestinal occlusion and 1 emoftoe due to pulmonary cavitation. In a further subgroup of 12 patients from the same center, we were able to evaluate hyperprogression that was observed in 7/12 (58%) patients. In the overall population, median PFS was 4.8 months.

Conclusion: In a real-world population of patients with advanced U-LMS treated with Pazopanib, the data of PFS and responses are consistent with literature. The variation of tumor density and CHOI criteria, should be considered in the evaluation of responses. However, clinicians must be careful during treatment due to the possibility of complicated response with the use of Pazopanib