Assessing Emactuzumab in Diffuse-Type Tenosynovial Giant Cell Tumors

the Cancer Therapy Advisor take:

Diffuse-type tenosynovial giant cell tumors (dt-GCTs), also called pigmented villonodular synovitis, is an orphan disease with an unmet medical need.

Further study and different possibilities involving multinational collaboration are being assessed in order to ensure appropriate recruitment for investigation of this rare disease, stated an article published online in the journal The Lancet Oncology.

Dt-GCTs are characterized by an overexpression of colony-stimulating factor 1 (CSF1), which leads to activation of the CSF1 receptor (CSF1R) that recruits CSF1R expressing cells that constitute the mass in dt-GCTs. Emactuzumab, RG7155, a novel monoclonal antibody, has been found to inhibit CSF1R activation.

In this study, patients with soft tissue dt-GCT were considered eligible if they were 18 years or older, had locally advanced disease or resectable tumors requiring extensive surgery, an ECOG performance status of 1 or less, measurable disease according to Response Evaluation Criteria in Solid Tumors version 1.1, and adequate end-organ function.

Results showed a total of 12 patients enrolled in the dose-escalation phase from July 26, 2012, to October 21, 2013, none of which experienced dose-limiting toxicities. Furthermore, 17 other patients received 1,000 mg every 2 weeks for the dose-expansion cohort.

The safety population was made up of 25 patients who were studied for adverse events. After emactuzumab administration, 16 out of the 25 patients (64%) had facial edema, 14 patients (56%) had asthenia, and 14 patients (56%) had pruritus.

The following adverse events were experienced by 1 (4%) patient each: periorbital edema, lupus erythematosus (occurring twice), erythema, and dermohypodermitis. One patient (4%) experienced grade 3 mucositis and one (4%) patient reported grade 3 fatigue.

Most patients (24 out of 28; 86%) achieved an objective response, and two (7%) patients attained a complete response.