Prolactinoma Response to Bevacizumab Is Influenced by Tumor Progression Stage at the Beginning of Treatment

SOFIA VALLA; DEMARCHI, GIANINA; PERRONE, SOFÍA; MARÍA FERNANDA PARENTI; BERNER, SILVIA INÉS; BECU-VILLALOBOS DAMASIA; CRISTINA CAROLINA

New Orleans , LA

Congreso; ENDOCRINE SOCIETY MEETING 2019; 2019

Endocrine Society

Anti-VEGF therapy is being implemented as second line drug for aggressive pituitary adenomas that do not respond to conventional treatments. Although it is approved for treatment of several cancers, many of them acquire resistance. In the present work, we evaluated Bevacizumab (BVZ) effect in an in vivo model of prolactinoma in different stages of tumor progression.Immunodeficient nu/nu mice were injected subcutaneously with MMQ tumoral lactotrophs and once xenografts developed, mice were divided in two groups: ?Early Onset Treatment (EOT)? or ?Late Onset Treatment (LOT)? depending on tumor size at the start of treatment (smaller than 30 mm3 or larger than 60 mm3, respectively). BVZ (25 mg/kg) or saline solution as control were administered twice a week for 2 weeks.When BVZ was administered in EOT group, treated mice showed a slower tumor growth rate than controls since the second week of treatment, although nosignificant differences in tumor volume were determined at the moment of sacrifice. On the contrary, this beneficial effect was not observed in LOT mice, which increased significantly tumor size in response to BVZ treatment (N=8 per condition in each group, p