Abstract 112P
Background
Pseudoprogression (PSP) is an initial increase in the size of the primary tumor or the appearance of the new lesions followed by a distinct decrease in tumor burden. Herein, we aimed to evaluate the effect of PSP on treatment response in patients with advanced non-small cell lung cancer (NSCLC).
Methods
We retrospectively analyzed patients with advanced NSCLC treated with immune checkpoint inhibitors in Cerrahpasa Medical Faculty clinical trial unit between 2014-2021. We defined PSP as a perceptible increase in tumor volume followed by subsequent clinical benefit beyond progression. All treatment responses were evaluated according to RECIST 1.1 criteria.
Results
Demographics of the entire study population are depicted in the table. Sixteen (17%) of the 90 patients were evaluated to have PSP. The median overall survival (OS) was 25 months in patients without PSP and 48,9 months in patients with PSP (p=0.008). Median progression-free survival (PFS) for PSP and non-PSP group was 13,5 months and 36,9 months, respectively (p=0.0036). The duration of response was 11,8 months in the non-PSP group and 36,6 months in the PSP group (p=0.0016). The results showed a statistically significant improvement in PFS and OS in favor of the PSP group. Table: 112P
Demographics of the entire study population
| Variable | PSP Group | Non-PSP Group |
| Number of patients | 16 | 74 |
| Age, mean, years | 61 | 61,5 |
| Female, n (%) | 61 (82,4) | 15 (93.7) |
| Mono ICI,n(%) | 14 (87,5) | 63 (85,1) |
| Dual ICI,n(%) | 0 | 4 (5,4) |
| Chemotherapy + ICI, n (%) | 2 (12,5) | 7 (9,5) |
Conclusions
Our study shows that PSP is not rare and related to good clinical outcomes. Recognizing pseudoprogression in clinical practice is critical to prevent premature discontinuation of ICI.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.