The serum and tissue expression of vascular endothelial growth factor-in recurrent respiratory papillomatosis

VEGF as a Key Actor in Recurrent Respiratory Papillomatosis: A Narrative Review

Recurrent respiratory papillomatosis (RRP) is a benign disease of the upper aerodigestive tract caused by human papillomavirus (HPV) types 6 and 11. The clinical course is unpredictable and some patients, especially younger children, experience a high rate of recurrence with a significant impact on their quality of life. The molecular mechanisms of HPV infection in keratinocytes have been extensively studied throughout the years, with particular regard to its role in causing malignant tumors, like cervical cancer and head and neck carcinomas. A minor but not negligible amount of the literature has investigated the molecular landscape of RRP patients, and some papers have studied the role of angiogenesis (the growth of blood vessels from pre-existing vasculature) in this disease. A central role in this process is played by vascular endothelial growth factor (VEGF), which activates different signaling cascades on multiple levels. The increased knowledge has led to the introduction of the VEGF inhibitor bevacizumab in recent years as an adjuvant treatment in some patients, with good results. This review summarizes the current evidence about the role of VEGF in the pathophysiology of RRP, the molecular pathways activated by binding with its receptors, and the current and future roles of anti-angiogenic treatment.

Clinico-pathological Factors in Malignant Transformation of RRP

Various clinico-pathological factors play role in the papilloma proliferation and pathogenesis of Recurrent respiratory papillomatosis (RRP). However, it is not known if they are directly responsible for malignant transformation of these papillomas or not. We did this study to elucidate any such association. The most recent debrided tissue of RRP in 20 patients was evaluated for p16 expression, VEGF estimation (tissue expression and serum levels), and tissue HPV DNA concentration. The final histopathology results were then correlated with these pathological factors and with clinical factors like duration of illness, age of onset of symptoms, extent of disease, etc. Squamous papilloma was seen in 60%, dysplasia in 25%, and squamous cell carcinoma (SCC) in 15% of the patients. Positive immunostaining for p16 (staining in ≥70% of tumor cells) was seen only in one case, which was SCC. There was no statistically significant difference between p16 expression, tissue VEGF expression, serum VEGF levels, and tissue HPV DNA in any of the histological groups. The mean age of disease onset was significantly higher in patients with SCC (p = 0.03). A significantly higher number of patients with dysplasia had tracheobronchial involvement (p = 0.022). We concluded that no single pathological factor is solely responsible for development of malignancy in RRP, whereas clinical factors like tracheobronchial involvement and age of onset may contribute to development of dysplasia or carcinoma.

Aggressive recurrent respiratory papillomatosis: A series of five consecutive patients successfully treated with adjuvant intravenous bevacizumab. A single Belgian academic center experience

BACKGROUND

Recurrent respiratory papillomatosis (RRP) is a currently incurable benign neoplasm caused by human papilloma virus (HPV) infection. It usually reduces voice, respiratory, and general quality of life, and is sometimes life-threatening. Patients usually need repeated operations. The use of adjuvant bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor A, has been described in several case reports, with a good efficacy and safety profile.

METHODS

We report the cases of five patients with aggressive RRP who were treated with adjuvant systemic bevacizumab in a single Belgian tertiary center.

RESULTS

A complete response was achieved in four patients after a median of 4.5 months, and a partial response in one. In all cases, the number of surgeries was drastically reduced, and quality of life improved. Toxicity was easily managed.

CONCLUSIONS

Systemic bevacizumab seems to be an effective and safe adjuvant treatment for aggressive RRP.