Circularly Permuted TRAIL (CPT) combined with Thalidomide for the Treatment of Relapsed or Refractory Multiple Myeloma: An Open-Label, Multicenter Phase II Clinical Trial.

Circularly permuted TRAIL (CPT) is a recombinant mutant of human Apo2L/TRAIL developed by Beijing Sunbio Biotech Co. Ltd. as a targeted therapy for multiple myeloma and other hematologic malignancies. CPT is a dual pro-apoptotic receptor agonist that directly activates both pro-apoptotic receptors TRAIL-R1 (DR4) and TRAIL-R2 (DR5). CPT selectively induces apoptosis in a variety of cancer cells, while sparing most normal cells in preclinical models.

CPT as a mono-therapy has shown definitive activities for patients with relapsed or refractory multiple myeloma (Rel/Ref MM) in phase I and phase II studies. The aim of this study is to observe the effect and safety of CPT in combination with thalidomide for Rel/Ref MM patients.

In this multiple-center, open-label, single arm phase II study, 43 Rel/Ref MM patients who had received prior therapies and were resistant to thalidomide were recruited. These patients were divided into three groups, and received CPT 5.0mg/kg, 8.0mg/kg, and 10.0mg/kg on days1–5 of each 21-day cycle, respectively, until having finished six cycle‘s treatment or progression disease or intolerant adverse events. All the patients received thalidomide 100mg daily until to the disease progression or intolerant adverse events. Clinical responses of CPT were assessed by an independent review committee according to the criteria of the European Group for Blood and Marrow Transplantation (EBMT).

Among the 43 patients, 41 patients can be evaluated. There were 11, 15 and 15 patients in the three groups respectively. Among the 41 patients, two patients achieved complete response (CR), three showed near complete responses (nCR), four exhibited partial responses (PR), and five obtained minor responses (MR). The total response rates were 34% (including MR or better than MR), or 22% (including PR or better than PR). Among the three groups, the dose of 10mg/kg seemed to be optimal with 26.7% response rate (including PR or better than PR), superior to the other two groups. Duration of response of CPT was not evaluated accurately, because most patients who achieved PR, nCR, or CR were progression free at the end of the trial. The common treatment related adverse events (≥10%) were neutropenia, leucopoenia, fever, AST/ALT/LDH elevation, and thrombocytopenia. The grade 3 non-haematological toxicities were AST elevation (4.65%) and LDH elevation (2.33%). The elevation of AST and LDH seems to be related to tumor lysis, but not to liver injury. The grade 4 haematological toxicities were neutropenia and thrombocytopenia (2.33%, respectively) which might be related to thalidomide.

The CPT combined with thalidomide was well-tolerated and an effective regimen for the treatment of Rel/Ref MM. The combination of CPT and thalidomide seems to be superior to CPT alone in CR/nCR response rate.

Zheng:Beijing Sunbio Biotech Co., Ltd.: Employment. Zhu:Beijing Sunbio Biotech Co., Ltd.: Employment. Yang:Beijing Sunbio Biotech Co., Ltd.: Employment.