Oral Paclitaxel-Encequidar Combo Appears Safe, Effective in Patients With Rare Subset of Breast Cancer

Among patients with radiation-associated breast angiosarcoma, treatment with an oral version of the chemotherapy drug paclitaxel in combination with a novel oral inhibitor, Encequidar, elicited encouraging results, according to phase 2 data presented at the 2020 San Antonio Breast Cancer Symposium.

Currently, according to the study authors, there are no available treatments approved by the Food and Drug Administration to treat this form of cutaneous angiosarcoma, which are rare and highly aggressive cancerous tumors that are usually associated with poor prognosis.

The study authors aimed to assess the activity, safety and tolerability of the oral combination in patients with unresectable breast cutaneous angiosarcoma, with the main goal of evaluating tumor response to therapy every six weeks.

Among 26 patients enrolled on the phase 2 trial from August 2018 to May 2020, seven patients (median age, 66 years; range, 49 to 76 years) were diagnosed with breast cutaneous angiosarcoma. All the patients with the rare condition had previously been diagnosed with breast cancer and received a mastectomy and radiotherapy and/or adjuvant chemotherapy.

The oral paclitaxel and Encequidar combination elicited a complete response, meaning disappearance of all signs of cancer in response to treatment, in three of the seven patients. One of the patients achieved a partial response and the remaining three had stable disease. Three of the patients who were deemed to have inoperable lesions eventually crossed over to receive curative surgical resection.

The combination was generally well tolerated with grade 3 (more serious) treatment-related adverse events occurring in five patients. The most common grade 3 treatment-related adverse events included fatigue (2 cases), diarrhea, dyspnea, dehydration, pneumonitis and neutropenia (one case each). Three patients needed dose reductions, however there were no treatment discontinuations as a result of adverse events. There have been no patient deaths to date, according to the authors.

The authors concluded that the combination may be an effective oral treatment for patients with radiation-associated breast angiosarcoma, with limited toxicities, which could offer patients the potential to avoid intravenous chemotherapy at a hospital.

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