Abstract 774P
Background
Immune checkpoint inhibitor (ICI) therapy, an emerging class of cancer treatment, is being actively investigated in multiple trials. However, the risk of venous thromboembolism (VTE) with ICI drugs remains unexplored.
Methods
MEDLINE and EMBASE databases were searched through 25th April 2022 to identify full text publications of phase 2/3 randomized controlled trials (RCTs) assessing ICI monotherapy compared to either chemotherapy or placebo and reporting adverse events. Main outcome of interest was VTE risk. A fixed-effect Peto meta-analysis was conducted to pool binary events data. Treatment effect estimates were expressed as odds ratio (OR) and 95% confidence interval (CI). Additional analyses were conducted by types of VTEs (deep vein thrombosis [DVT], pulmonary embolism [PE]), and class of ICI (PD1, PDL1). A sensitivity analysis using empirical informative priors was also conducted within the Bayesian framework.
Results
Of initial 16144 citations identified, 55 RCTs met our inclusion criteria. However, only 45 (61 references) reported VTE and were included in this meta-analysis; 35 trials comparing ICI monotherapy with chemotherapy in 19696 patients and only 10 trials comparing ICI monotherapy with placebo in 7191 patients. A total of 152 VTE events (1.44%) were observed in ICI monotherapy compared to 149 VTE events (1.64%) observed in chemotherapy arm. The difference was not statistically significant (OR: 0.87 95% CI: 0.69-1.09). Similarly, 35 VTE events (0.85%) were observed with ICI monotherapy as compared to 24 VTE events (0.78%) in placebo arm (Table). The difference was not statistically significant (OR: 0.95 95% CI: 0.56-1.61). The results were consistent for different types of VTE (DVT and PE), class of ICI (PD1 and PDL1), and by Bayesian meta-analysis. Table: 774P
Venous thromboembolism risk
| Participants (RCTs) | Relative risk (95% CI) | Anticipated absolute risks | ||
| Risk with Control | Risk difference with ICI | |||
| ICI vs Chemotherapy | 19696 | OR 0.87 | 16 per 1000 | 2 fewer per 1,000 |
| 35 RCTs | (0.69 to 1.09) | (5 fewer to 1 more) | ||
| ICI vs Placebo | 7191 | OR: 0.95 | 8 per 1,000 | 0 fewer per 1,000 |
| 10 RCTs | (0.56 to 1.61) | (3 fewer to 5 more) |
Conclusions
ICI monotherapy may not be associated with an increased risk of VTE in patients with cancer when compared to either chemotherapy or placebo.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Nihal Ijaz Khan.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.