A single-arm confirmatory trial of pazopanib in patients with paclitaxel-pretreated primary cutaneous angiosarcoma: Japan Clinical Oncology Group study (JCOG1605, JCOG-PCAS protocol).

Background: Paclitaxel is a standard of care for patients with primary cutaneous angiosarcoma of the scalp and face. However, no standard second-line treatment for paclitaxel-resistant patients has ever been established. Since primary cutaneous angiosarcoma expresses a high level of vascular endothelial growth factor receptor, the multitargeted tyrosine kinase inhibitor pazopanib seemed to be the most promising agent, and several retrospective studies have demonstrated its activity against this disease. However, the efficacy and safety of pazopanib in paclitaxel-resistant patients with primary cutaneous angiosarcoma have never been evaluated in a clinical trial.

Methods: In February 2018 the Dermatologic Oncology Group of Japan Clinical Oncology Group started a single-arm confirmatory trial to evaluate the efficacy and safety of pazopanib as a second-line treatment for patients with primary cutaneous angiosarcoma whose disease was resistant to paclitaxel or who were unable to tolerate paclitaxel (JCOG1605, JCOG-PCAS). Patients with primary cutaneous angiosarcoma not associated with lymphedema or radiation, progressing despite first-line paclitaxel monotherapy are included in the study. No prior systemic chemotherapy other than paclitaxel is permitted. Pazopanib is administered orally at an initial dosage of 800 mg once daily. Dose modifications for adverse events are made according to the dose reduction criteria described in the protocol. Treatment is continued until recurrence, disease progression, unacceptable toxic effects, patient refusal, or death. The primary endpoint is progression-free survival, secondary endpoints include overall survival, response rate, disease control rate, adverse events, and serious adverse events. We plan to recruit 30 participants in 5.5 years from 23 Japanese institutions. The follow-up period is set as 1 year after completion of accrual. The study protocol was approved by the Japan Clinical Oncology Group Protocol Review Committee in December 2017. Ethical approval for this study was granted by Ethics Committee of each institute.

Discussion: If the primary endpoint is met, pazopanib will be regarded as a standard of care for paclitaxel-resistant patients for whom no standard second-line treatment is established.

Trials Registration: Registry number: UMIN000031438 [ http://www.umin.ac.jp/ctr/index.htm ]. Date of Registration: 23/Feb/2018. Date of First Participant Enrollment: 8/Mar/2018.