MABp1 (Xilonix), a novel first-in-class True Human monoclonal (IgG1k) antibody, has shown positive results for patients with advanced, symptomatic colorectal cancer in a European phase 3 study by XBiotech.1
There were 132 700 new cases of colorectal cancer in the United States in 2015, and those with metastatic disease had only an 11% survival rate.2 These patients may experience significant symptomatic effects of the tumor, along with a high tumor burden, which are not typically expected to completely resolve.
MABp1 specifically targets and neutralizes interleukin-1 alpha, which is known to promote angiogenesis, tumor growth, and metastasis, and mediates symptoms such as anxiety, fatigue, and metabolic dysregulation in patients with advanced colorectal cancer. MABp1 is an example of XBiotech’s True Human antibodies that are cloned directly from individual donors who are naturally immune to certain diseases.1
Investigators enrolled 333 patients in a double-blind, placebo-controlled, phase 3 trial. The patients had metastatic or unresectable colorectal cancer, were refractory to standard oxaliplatin- and irinotecan-based chemotherapy, and were experiencing malignancy-associated symptoms, such as fatigue, pain, elevated inflammatory markers, weight loss, and reduced physical ability. Participants were randomly assigned 2:1 to receive best supportive care plus MABp1 intravenously every 2 weeks or placebo for 8 weeks.1
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Changes in lean body mass and health status were the co-primary endpoints used to evaluate efficacy. The endpoints were assessed by radiography and the EORTC-QLQ-C30 instrument, respectively.
Results determined that 33% of the 207 patients who received MABp1 responded to the novel therapy, compared with 19% of the 102 patients who received placebo (P = .009). Researchers also found that median platelet counts among patients who received placebo were 5-fold higher than those who received MABp1. Patients taking MABp1 had their platelet counts remain near baseline levels throughout the treatment cycle (P = .003).