1492P - Retrospective study of the real-world safety profile of extended dosing 6-weekly pembrolizumab in comparison to traditional 3-weekly dosing schedule for treatment of lung cancer and melanoma in a Queensland hospital

Background

Due to the widespread uptake of 6-weekly Pembrolizumab (6wklyP) in the COVID-19 era, this audit attempts to clarify differences in clinically relevant immune therapy related adverse events (irAEs) between 6wklyP and traditional 3-weekly Pembrolizumab (3wklyP).

Methods

Oncology patients at the Gold Coast University Hospital with Advanced Melanoma or Metastatic Non-small cell lung cancer (NSCLC) who received single agent 3wklyP 200mg, 6wklyP 400mg or those who sequentially received 3wklyP followed by 6wklyP between 2017-2022 were analysed for frequency of clinically significant (Grade3-4) irAEs. Total time of immunosuppression for treatment of irAEs was recorded. Data was extracted from the electronic medical record and analysed using Cox-proportion hazard analysis.

Results

In total, 69 and 112 patients received 6wklyP and 3wklyP respectively. There were 52 patients with Melanoma and 129 patients with NSCLC. 30 patients received sequential treatment. Average observation time for toxicity was 327 days for 6wklyP and 352 days for 3wklyP. 17/69 (24.6%) patients who received 6wklyP developed Grade 3-4 irAEs compared with 9/112 (8%) 3wklyP patients (HR of 3.03; CI 1.34-6.83, p= 0.007). Grade 1-4 irAEs were 32/69 (46.4%) with 6wklyP and 31/112 (27.7%) with 3wklyP. 6/30 (20%) patients who received 6wklyP after initially receiving 3wklyP had Grade 3-4 irAEs (HR 0.56, CI 0.24-1.37; p= 0.187). Mean immunosuppression time for treatment of Grade 3-4 irAEs for 6wklyP and 3wklyP was 91 days and 55 days respectively (p =0.76). 6/17 (35.3%) 6wklyP patients required Steroid sparing agents to treat their Grade3-4 irAEs compared to 1/9 (11.1%) 3wklyP patients.

Conclusions

6wklyP was associated with significantly higher immune therapy related adverse events than 3wklyP. Sequential delivery of 6wklyP after 3wklyP did not significantly alter clinically significant adverse effects. Immunosuppressive management of irAEs were not statistically different between arms however there was a higher rate of steroid sparing immunomodulation requirement with 6wklyP.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.