The CDK 4/6 inhibitor ribociclib has activity in the treatment of inoperable desmoid tumor. A case report

Summary

The effect of systemic treatments in desmoid tumors (DT) is inconsistent, calling for novel approaches. We report here a prolonged disease stabilization with ribociclib combined with goserelin and letrozole in a patient with multiple aggressive DTs resistant to endocrine treatment alone. A 19-year-old otherwise healthy female was diagnosed with multifocal DTs. She had a familial history of FAP and a colectomy was preformed previously. During the long treatment of this patient, management guidelines of DTs have changed toward a more conservative approach. In this patient, six DTs were operated in eight operations, one recurrent tumor was resected six times. Due to rapid growth, three DTs were treated with four separate RT courses and one tumor was irradiated twice. The patient was treated with tamoxifen, oral vinorelbine, pegylated liposomal doxorubicin, toremifen, toremifene combined wtih goserelin, and letrozole combined with goserelin. The DTs did not respond to cytotoxic drugs nor tamoxifen. Upon progression during goserelin and letrozole therapy in January 2017 ribociclib 600 mg was added. During this treatment, pain was relieved and the total dose of opiods was diminished. The best response according to World Health Organization (WHO) criteria was stable disease with maximal size reduction of 18% in the sum of the product of bi-dimensional measurements. Due to grade 4 neutropenia, the dose was reduced to 400 mg and then further to 200 mg. In October, grade 4 neutropenia recurred, the pain was increased and one lesion enlarged significantly, and ribociclib was discontinued though formal criteria for progressive disease were not reached.