Pembrolizumab is a monoclonal antibody that binds to immune checkpoints, reactivates the immune system suppressed by cancer cells, and thus helps the body to recognise, attack and destroy cancer cells. In pivotal clinical studies, pembrolizumab was dosed according to the patient's body weight, at 2 mg/kg body weight every 3 weeks. However, in more recent clinical studies, pembrolizumab was dosed at a fixed dose, regardless of body weight, at 200 mg every 3 weeks or 400 mg every 6 weeks. Since most cancer patients weigh less than 100 kg, most would receive a lower dose than 200 mg if pembrolizumab was dosed according to the body weight.
Our study aimed to describe the treatment characteristics, dosing regimen and total consumption of pembrolizumab in patients with advanced non-small lung cancer, treated with first line pembrolizumab at the University Clinic Golnik, and to evaluate the possibility of reducing the consumption of pembrolizumab if dosed according to the body weight.
We conducted a retrospective observational study of 124 patients with advanced non-small lung cancer who started first-line treatment with pembrolizumab at the University Clinic Golnik between August 2017 and December 2021. Patient data were obtained from the hospital information system BIRPIS and patient medical records. Based on the number of pembrolizumab doses received and the duration of treatment, the pembrolizumab dose received by patients every 3 weeks and the total pembrolizumab consumption were calculated. This was done for three pembrolizumab dosing regimens: i) pembrolizumab treatment as received by patients, ii) pembrolizumab treatment according to the approved dosing regimen, and iii) pembrolizumab treatment while adjusting the dose according to the body weight.
The 124 patients included received an average of 8 administrations of pembrolizumab at a dose of 200 mg and were treated for an average of 24 weeks. Therefore, on average, patients had received 190 mg of pembrolizumab every 3 weeks. If the approved dosing regimen is followed, patients would always receive 200 mg of pembrolizumab every 3 weeks. If the pembrolizumab dose was adjusted according to the body weight, patients would receive an average of 146 mg of pembrolizumab every 3 weeks. In the cohort of 124 enrolled patients, a total of 283,600 mg of pembrolizumab was used. This is 44,200 mg of pembrolizumab less than if the approved dosing regimen was followed. Adjusting the dose of pembrolizumab according to the body weight would have saved an additional 32,400 mg.
Dosing pembrolizumab according to the body weight, as initially approved, could significantly reduce the consumption of pembrolizumab compared with fixed-dosing as currently approved.
|