OS03.5.A Characterization of the inflammatory tumor microenvironment composition in solid cancer patients with brain metastases after progression to immune checkpoint inhibitor therapy

Background

Immunotherapy (IO) has changed the treatment landscape of metastatic cancer patients, however, treatment resistance is frequent. We aimed to characterize the inflammatory tumor microenvironment in brain metastases (BM) after IO to gain a deeper understanding of immunologic escape mechanisms.

Material and Methods

Solid cancer patients who had BM resection after IO progression (IO cohort) were retrospectively identified. We analyzed tumor-infiltrating immune cell subsets (CD3, CD8, CD45RO, FOXP3) and expression of immune checkpoint molecules (PD-L1, PD-1, LAG-3) by immunohistochemistry. A control cohort of BM tissue samples without prior IO served for comparison (no immunotherapy cohort, NIO).

Results

Twenty-eight IO patients (12/28, 42.9% females; 16/28, 57.1% males; median 61 years; 14/28, 50% lung cancer; 5/28, 17.9% melanoma; 4/28, 14.3% renal cell carcinoma; 1/28, 3.6% breast cancer; 4/28, 14.3% other cancer entities) and 57 NIO patients (28/57, 49.1% females; 29/57, 50.9% males; median 58 years; 35/57, 61.4% lung cancer; 9/57, 15.8% breast cancer; 4/57, 7.0% melanoma; 3/57, 5.3% renal cell carcinoma; 6/57, 10.5% other cancer entities) were included. IO patients had a median of one (range 0-4) systemic therapy line prior to IO. Median time from last IO application until BM resection was 5.6 months (range 0.2-49.8 months). Patients received a median number of 7 (range 1-56) IO applications (14/28, 50% PD-1-targeting IO; 8/28, 28.6% PD-L1; 2/28, 7.1% CTLA4; 4/28, 14.3% CTLA4+PD-1; 3/28, 10.7% IO+chemotherapy). No statistically significant differences in the densities of investigated TILs or PD-L1 expression between the IO and the NIO cohort were observed. Patients of the IO cohort showed higher PD-L1 expression compared to the NIO cohort (57.1 vs. 42.1%, Chi-square, p>0.05). Overall survival (OS) was similar in both cohorts, with a median OS of 11.0 months (range 5.0-17.0) in the IO cohort and 11.0 months (range 5.5-16.5) in the NIO cohort.

Conclusion

Our findings show an upregulation of PD-L1 in BM occurring after prior IO therapy in the absence of other overt changes in the inflammatory microenvironment. Ongoing analyses in this cohort are investigating possible molecular driver of resistance by analyzing DNA methylation profiles of pre-and post-IO tissue samples of the IO cohort to potentially gain insights on inflammatory IO resistance mechanisms in BM patients.

Budesonide in glucocorticoid dependent chronic active Crohn's disease; a pilot study

Patients with chronic active Crohn's disease are dependent on systemic glucocorticosteroids. The aim of the study was to investigate the efficacy of budesonide, a topically selective glucocorticosteroid, as therapy in these patients. We investigated 20 patients with chronic active Crohn's disease. During the last 6 months prior to the study the patients had a median Crohn's disease activity index (CDAI) of 193 (interquartile range: 122-230) (monthly controls) with a median prednisolone dosage of 14 mg per day (9-20). Budesonide was given 3 to 6 mg daily and prednisolone was weaned within one month. The patients were seen monthly for 6 months. Treatment was considered not successful, if under budesonide therapy CDAI was above 200 and increased more than 60 points despite weaning of prednisolone. Only 5 patients remained in the study for 6 months without deterioration. All other patients (75%) dropped out. The reasons for drop out of the study were worsening in 11 cases, the occurrence of extraintestinal manifestations without signs of severe intestinal inflammation in one case and noncompliance in 3 cases. Worsening could be confirmed by an increase not only of CDAI but also of biochemical parameters of inflammation in all cases. Our data show clearly, that in the dosage investigated budesonide was not effective in chronic active Crohn's disease. Further investigations are needed to evaluate higher dosages of budesonide versus conventional glucocorticosteroids.

Finite-element analysis of balloon angioplasty

Finite-element modelling is used to simulate the response of atherosclerotic arteries to a balloon angioplasty procedure. Material properties for the normal wall are derived from experimental data, and the properties of the plaque are varied over a wide range. Comparison with experimental data shows that the normal arterial wall can be appropriately modelled using a hyperelastic material definition. Large strain, non-linear analysis was used to simulate the dilatation of three typical plaque configurations by an angioplasty balloon. Stress contour plots are presented for each configuration. Results show good agreement with previous histologic studies.