Arterial effects of anthracycline: structural and inflammatory assessments in non-human primates and lymphoma patients using 18F-FDG positron emission tomography

Abstract

Background: Anthracyclines, such as doxorubicin, are important anti-cancer therapies but are associated with arterial injury. Histopathological insights have been limited to small animal models and the role of inflammation in the arterial toxic effects of anthracycline is unclear in humans. Our aims were: 1) To evaluate aortic media fibrosis and injury in non-human primates treated with anthracyclines; 2) To assess the effect of anthracycline on aortic inflammation in patients treated for lymphoma.

Methods: 1) African Green monkeys (AGM) received doxorubicin (30-60 mg/m²/biweekly IV, cumulative dose: 240 mg/m²). Blinded histopathologic analyses of collagen deposition and cell vacuolization in the ascending aorta were performed 15 weeks after the last doxorubicin dose and compared to 5 age- and gender-matched healthy, untreated AGMs. 2) Analysis of the thoracic aorta of patients with diffuse large B-cell lymphoma (DLBCL), at baseline and after doxorubicin exposure, was performed using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in this observational study. The primary outcome was change in maximal tissue-to-background ratio (TBRmax) of the thoracic aorta from baseline to their end-of-treatment clinical PET/CT.

Results: In AGMs, doxorubicin exposure was associated with greater aortic fibrosis (collagen deposition: doxorubicin cohort 6.23±0.88% vs. controls 4.67±0.54%; p=0.01) and increased intracellular vacuolization (doxorubicin 66.3 ± 10.1 vs controls 11.5 ± 4.2 vacuoles/field, p<0.0001) than untreated controls.In 101 patients with DLBCL, there was no change in aortic TBRmax after anthracycline exposure (pre-doxorubicin TBRmax 1.46±0.16 vs post-doxorubicin TBRmax 1.44±0.14, p=0.14). The absence of change in TBRmax was consistent across all univariate analyses.

Conclusions: In a large animal model, anthracycline exposure was associated with aortic fibrosis. In patients with lymphoma, anthracycline exposure was not associated with aortic inflammation.Further research is required to elucidate the mechanisms of anthracycline-related vascular harm.

Keywords: PET; anthracycline; doxorubicin; fibrosis; lymphoma; vascular toxicity.

Figure 1.. Intracellular vacuolization within the aortic media of monkeys exposed to doxorubicin compared with controls.

Histopathological assessment of hematoxylin-eosin stained aortas. A: Graphical representation of the number of vacuoles present in the arterial wall in the control arm (CTL) and the doxorubicin treated arm (Dox), p<0.0001. (B). Representative microphotographs of hematoxylin-eosin stained aortas at 10X and 40X magnification. Black arrows indicate cardiomyocytes with intracellular vacuolization. All values are mean ± SEM.

Figure 2.. Collagen fiber deposition in the aortic media of monkeys exposed to doxorubicin compared with controls.

Assessment of ascending aorta media deposition of interstitial collagen. Graphical representation of collagen volume fraction (A) in aortas of untreated controls (blue bar, n=5) and Dox-treated AGMs (red bar, n=5). Representative microphotographs (20X) of aortas of untreated controls (B) and Dox-treated AGMs(C). Collagen is stained blue (highlighted by black arrows), and the cytoplasm of smooth muscle cells is stained red and pink in the microphotographs. All values are mean ± SEM. * p=0.01

Figure 3. FDG uptake of the thoracic aorta in patients with lymphoma before and after treatment with anthracycline-based chemotherapy

Boxplot of the mean TBRmax of the whole aorta pre and post anthracycline exposure, p=0.14.

Figure 4.. Change in mean TBRmax y baseline aortic calcium score in patients with lymphoma before and after treatment with anthracycline-based chemotherapy.

The change in aortic TBRmax from before and after anthracycline compared with quartiles of aortic calcification, p=0.42.