Therapeutic drug monitoring of nivolumab in routine clinical practice. A pilot study.

Objective: A review of the literature about the anti-programmed death 1 monoclonal antibody nivolumab permits to verify the existence  of several issues still unresolved about their dosing schedule. The aim of the present work was to explore possibilities of nivolumab treatment  personalization through therapeutic drug monitoring, in order to  improve their effectiveness and efficiency. Method: Observational, prospective study carried out from May 2017  through June 2019 in patients with different tumor diagnoses treated with nivolumab. Blood samples were obtained in the routine  clinical practice, once nivolumab steady state was reached. Serum  nivolumab levels were determined by means of quantitative ELISA. The  standard schedule of 3 mg/kg every two weeks (Q2W) was modified in  some patients due to different circumstances, and resulting serum  concentrations were compared with those from the non-modified  patients and the published data. Results: Blood samples from 19 patients in treatment with nivolumab were analyzed. A total of 39 samples of nivolumab were  analyzed between 6th and 27th cycles. The standard schedule of 3  mg/kg every two weeks was modified in 12/19 (60%) patients, with  intervals of 3, 4, 5, 6 or 7 weeks, once the steady state was reached.  No statistically significant differences were detected when comparing  every two weeks and every four week intervals. When the intervals  were six or seven weeks, mean plasma concentration showed a  statistically significant difference compared with every two weeks. Conclusions: Current data contribute to confirm former suspects about the possibilities of exploring new scenarios to improve and  personalize nivolumab dosage. Additional studies to confirm it in bigger  series and correlate it with clinical results, and to better define the role  of therapeutic drug monitoring in the treatment, are warranted, not only by financial concerns but also for improving quality of life of patients  and clinical management aspects.