Abstract 1138P
Background
Pembrolizumab 200mg every 3 week (Q3W) is the standard of care for patients with advanced non-small cell lung cancer (NSCLC) and PDL1 ≥ 50%. In April 2020, the FDA approved 400 mg every 6 weeks (Q6W) based on pharmacokinetic modeling without formal comparative studies. Pharmacokinetic studies also suggested that weight-based and flat dosing for the respective schedules have comparable target engagement. The objective of this study was to evaluate the overall survival (OS) based on the Q3W versus Q6W pembrolizumab dosing schedule.
Methods
A retrospective study of stage IV NSCLC PDL1 ≥ 50% patients referred to BC Cancer between 2017-2021 treated with pembrolizumab was conducted. Patients were treated per institution standard with weight-based dosing of pembrolizumab 2 mg/kg Q3W or 4 mg/kg Q6W. Patient demographics, treatments and outcomes were collected. Patients were assigned to Q3W or Q6W according to the schedule that was used for the majority (greater than 50%) of their treatment.
Results
718 NSCLC patients received first-line pembrolizumab: Q3W/Q6W dosing 677/41 patients. Baseline characteristics were similar between groups with more males and unknown PS in Q6W dosing. There was no difference in age, histology or smoking status between groups. In the multivariate model including age, sex, PS and dosing schedule, the HR for Q3W versus Q6W was 0.660 (p=0.116). A case matched analysis for OS was performed controlling for age +/- 5 years, sex, PS, duration on pembrolizumab +/- 2 months for Q3W vs Q6W (n=74) demonstrating HR 0.79; 95% CI 0.41-1.52, (p= 0.48). Table: 1138P
Univariate and multivariate analysis for OS
| HR (95% CI) Univariate analysis | p- value | HR (95% CI) Multivariate analysis | p-value | |
| Age | 1.001 (0.991-1.011) | 0.872 | 0.997 (0.987-1.007) | 0.554 |
| Sex Female versus Male | 1.071 (0.888-1.291) | 0.473 | 1.048 (0.869-1.265) | 0.622 |
| ECOG PS 0-1 versus ≥ 2 | 1.912 (1.585-2.305) | <0.001 | 1.901 (1.574-2.297) | <0.001 |
| Pembrolizumab schedule Q3W versus Q6W | 0.616 (0.368-1.032) | 0.066 | 0.660 (0.393-1.107) | 0.116 |
Conclusions
There was no survival difference demonstrated when dosing pembrolizumab Q3W compared to Q6W in multivariate analysis including age, sex and PS. A case matched analysis that also controlled for duration of treatment confirmed these findings. These results support the use of Q6W pembrolizumab dosing which allows for less frequent interactions with the medical system which improves patients’ quality of life.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
R. Rittberg: Financial Interests, Institutional, Research Grant: AstraZeneca. Y. Wang: Financial Interests, Personal, Invited Speaker: AstraZeneca, Takeda, Merck; Financial Interests, Institutional, Research Grant: Roche, AstraZeneca. C. Ho: Financial Interests, Personal, Advisory Board: AbbVie, Amgen, AstraZeneca, Bayer, BMS, Eisai, EMD Serono, Janssen, Merck, Novartis, Pfizer, Roche, Takeda; Financial Interests, Institutional, Research Grant: AstraZeneca, EMD Serono, Roche; Non-Financial Interests, Principal Investigator: Roche, AstraZeneca, EMD Serono. All other authors have declared no conflicts of interest.