Abstract 1600P
Background
A dose of 200mg 3-weekly of pembrolizumab was approved by the Foood and Drug Administration as treatment for advanced NSCLC without oncogenic drivers. This is despite evidence showing no difference in pharmacodynamics with 1mg/kg. KEYNOTE-001 also demonstrated no differences in efficacy with 2mg/kg or 10mg/kg. An average Asian weighs 50-60kg. Patients in our institution were given a lower fixed dose of 100mg.
Methods
A review of all patients receiving pembrolizumab for advanced NSCLC from January 2016 to March 2020 in an academic medical centre, National University Hospital, Singapore, was conducted. We investigated the effect of pembrolizumab 100mg (Pem100) versus 200mg (Pem200). Kaplan Meier and Cox regression model were used for survival analysis.
Results
104 patients received pembrolizumab. Median age was 67 years (Range, 29-92). Most were males (77%), Chinese (73%) and average weight was 59kg. 59 (57%) and 45 (43%) received Pem100 and Pem200 respectively. Average dose received was 2.44mg/kg (Range, 1.35 – 4.98mg/kg). At a median follow up of 14.8 months, there was no difference in progression-free survival (PFS) and overall survival (OS) between Pem100 vs. Pem200 as a single agent (PFS: 6.8 vs. 4.2months, HR 0.72 95% CI 0.36-1.46 p=0.36; 9 month OS: 58% vs. 63%, HR 1.08 95% CI 0.48-2.41 p=0.86) and when combined with chemotherapy (9 month PFS: 60% vs. 50%, HR 0.84 95% CI 0.34-2.08 p=0.71; 9 month OS: 85% vs. 58%, HR 0.27 95% CI 0.062-1.20 p=0.09). Single agent pembrolizumab <2mg/kg (n=28) versus ≥2mg/kg (n=32) also showed no significant difference in PFS (HR 0.98 95%CI 0.52-1.85 p=0.96) and OS (HR 1.04 95% CI 0.51-2.13 p=0.91). Response rate for Pem100 and Pem200 as a single agent and when combined with chemotherapy did not differ (RR: 40% vs. 29%, p=0.43 and 46% vs. 48%, p=0.91). No significant difference in ≥G3 immune-related adverse events between Pem100 and Pem200 was observed (15% vs. 22%, p=0.36). Median number of cycles received was 7 (Range, 1-70 cycles), translating to estimated cost savings of SGD 39 893 (1 SGD≈0.65 Euro) (Range, SGD 5 699 – 398 930) per patient if Pem100 was used.
Conclusions
100mg of pembrolizumab is effective with significant reduction in cost. A randomised trial should be done to investigate a lower dose of pembrolizumab.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Low Jia Li.
Funding
Has not received any funding.
Disclosure
R. Soo: Honoraria (self), Advisory/Consultancy, Research grant/Funding (self): Astra Zeneca; Boehringer Ingelheim; Honoraria (self), Advisory/Consultancy: Bristol Myers Squibb; Merck; Novartis; Pfizer; Roche; Yuhan; Takeda; Amgen; Advisory/Consultancy: Taiho; Honoraria (self): Lilly. S. Raghav: Honoraria (self), Advisory/Consultancy: Bristol-Myers Squibb; Advisory/Consultancy, Travel/Accommodation/Expenses: Eisa; Honoraria (self), Advisory/Consultancy, Travel/Accommodation/Expenses: Taiho; Advisory/Consultancy: Bayer; Merck; Honoraria (self), Travel/Accommodation/Expenses: Roche; Travel/Accommodation/Expenses: Astra Zeneca; Honoraria (self), Research grant/Funding (self): MSD; Honoraria (self): Lilly; Research grant/Funding (institution): Paxman. W.P. Yong: Advisory/Consultancy: Abbvie/Genentech; Amgen; Bristol Myers Squibb; Ipsen; Novartis; Speaker Bureau/Expert testimony: Lily; Sanofi/Aventis; Taiho; Eisai; Travel/Accommodation/Expenses: Pfizer. All other authors have declared no conflicts of interest.