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INTRODUCTION: Daratumumab is a CD38-targeting monoclonal antibody that has demonstrated clinical benefit for multiple myeloma. Daratumumab inhibition of CD38, which is expressed on immune cell populations and cardiomyocytes, could potentially affect cardiac function. This QTc substudy of the phase 2 CENTAURUS study investigated the potential effect of intravenous daratumumab monotherapy on QTc prolongation and other electrocardiogram (ECG) parameters, including concentration-QTc effect modeling. METHODS: Patients had intermediate- or high-risk smoldering multiple myeloma. Patients with QT interval corrected by Fridericias formula (QTcF) > 470 ms, QRS interval ≥ 110 ms, or PR interval ≥ 200 ms were excluded. Triplicate ECGs were collected at screening, Dose 1, and Dose 8. Analyses of on-treatment ECGs were conducted with a time-matched baseline (primary analysis). By time-point, pharmacokinetic-pharmacodynamic (PK/PD), and outlier analyses were conducted. RESULTS: Of 123 patients in CENTAURUS, 31 were enrolled in the QTc substudy. Daratumumab produced a small increase in heart rate (5-12 beats per minute) of unclear significance. There was a small but clinically insignificant effect on QTc, as measured by both time-matched time-point and PK/PD analyses. The primary analysis demonstrated a maximum mean increase in QTcF of 9.1 ms (90% 2-sided upper confidence interval [CI], 14.1 ms). The primary PK/PD analysis predicted a maximum QTcF increase of 8.5 ms (90% 2-sided upper CI, 13.5 ms). No patient had an abnormal U wave, a new QTcF > 500 ms, or > 60 ms change from baseline for QTcF. CONCLUSION: Analysis of ECG intervals and concentration-QTc relationships showed a small but clinically insignificant effect of daratumumab. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02316106.

Current guidelines for smoldering multiple myeloma (SMM) recommend active monitoring until the onset of multiple myeloma (MM) before initiating treatment or enrollment in a clinical trial. Earlier intervention may delay progression to MM. In CENTAURUS, 123 patients with intermediate-risk or high-risk SMM were randomly assigned to daratumumab 16 mg/kg intravenously on extended intense (intense), extended intermediate (intermediate), or short dosing schedules. At the prespecified primary analysis (15.8-month median follow-up), the complete response (CR) rates (co-primary endpoint) were 2.4%, 4.9%, and 0% for intense, intermediate, and short dosing, respectively; the co-primary endpoint of CR rate >15% was not met. Progressive disease (PD)/death rates (number of patients who progressed or died divided by total duration of progression-free survival [PFS] in patient-years; co-primary endpoint) for intense, intermediate, and short dosing were 0.055 (80% confidence interval [CI], 0.014-0.096), 0.102 (80% CI, 0.044-0.160), and 0.206 (80% CI, 0.118-0.295), respectively, translating to a median PFS ≥24 months in all arms (P

This work experimentally confirms the pathway of activation of Ha- ras-p21, which was calculated by the method of Targeted Molecular Dynamics (TMD) (Díaz JF, Wroblowski B, Schlitter J, Engelborghs Y, 1997a, Proteins Struct Funct Genet 28:434-451). The process can be studied experimentally by analyzing the binding of BeF3− to the GDP complex of the active fluorescent mutant Y32W (Díaz JF, Sillen A, Engelborghs Y, 1997b, J Biol Chem 227:23138-23143). Two mutants, V29G and I36G, have been constructed at both sides of the effector loop of the active fluorescent mutant. This was done to check the proposed reaction pathway and to provide further insight into the mechanism of the activation of ras proteins. Both mutations accelerate the conformational isomerization with two orders of magnitude, demonstrating convincingly the role of these residues as hinges of the effector loop in one or more of the transitions of the conformational change. These results provide experimental support to the pathway calculated by TMD analysis. [ABSTRACT FROM AUTHOR]