A Pilot Study of Preoperative Vandetanib on Markers of Proliferation and Apoptosis in Breast Cancer

INTRODUCTION

Preclinical data supports antitumor activity of tyrosine kinase inhibitor vandetanib with Ret as the therapeutic target in breast cancer. We investigated the effect of preoperative vandetanib on markers of proliferation and apoptosis in breast cancer.

METHODS

Patients with invasive breast cancer were randomly assigned vandetanib 300 mg or placebo PO daily for 2 weeks before operative resection from January 2014 to June 2017. Pretreatment and posttreatment specimens were analyzed by immunohistochemistry for Ki-67, TUNEL, and p-ERK with stratification by Ret expression by immunohistochemistry.

RESULTS

Ten patients were enrolled. There was no statistically significant difference in ERK activation compared with placebo (P=0.45); however, ERK activation was reduced 74% compared with pretreatment biopsy with vandetinib treatment (P=0.005) without a significant reduction in the placebo group (-29%, P=0.55). Mean change in Ki-67 after vandetanib treatment was +0.3% compared with +2.0% in placebo treated patients, P=0.72. Mean change in TUNEL was +0.48 apoptotic nuclei per HPF in the vandetanib arm compared with +1.02 in the placebo arm, P=0.32. In vandetanib treated patients, Ki-67 was reduced 0.3% in RET-positive tumors compared with increased 1.0% in RET-negative tumors, P=0.43 and TUNEL was increased 0.77 in RET-positive tumors and 0.2 in RET-negative tumors, P=0.21.

CONCLUSIONS

In this pilot study, no statistically significant differences on prespecified markers were seen with vandetanib compared with placebo. In accordance with the investigational hypothesis, there was a nonsignificant trend with vandetanib treatment of reduction in p-ERK and increased effects in Ret expressing tumors.

Multiple endocrine neoplasias type 2B and RET proto-oncogene

Multiple Endocrine Neoplasia type 2B (MEN 2B) is an autosomal dominant complex oncologic neurocristopathy including medullary thyroid carcinoma, pheochromocytoma, gastrointestinal disorders, marphanoid face, and mucosal multiple ganglioneuromas. Medullary thyroid carcinoma is the major cause of mortality in MEN 2B syndrome, and it often appears during the first years of life. RET proto-oncogene germline activating mutations are causative for MEN 2B. The 95% of MEN 2B patients are associated with a point mutation in exon 16 (M918/T). A second point mutation at codon 883 has been found in 2%-3% of MEN 2B cases. RET proto-oncogene is also involved in different neoplastic and not neoplastic neurocristopathies. Other RET mutations cause MEN 2A syndrome, familial medullary thyroid carcinoma, or Hirschsprung's disease. RET gene expression is also involved in Neuroblastoma. The main diagnosis standards are the acetylcholinesterase study of rectal mucosa and the molecular analysis of RET. In our protocol the rectal biopsy is, therefore, the first approach. RET mutation detection offers the possibility to diagnose MEN 2B predisposition at a pre-clinical stage in familial cases, and to perform an early total prophylactic thyroidectomy. The surgical treatment of MEN 2B is total thyroidectomy with cervical limphadenectomy of the central compartment of the neck. When possible, this intervention should be performed with prophylactic aim before 1 year of age in patients with molecular genetic diagnosis. Recent advances into the mechanisms of RET proto-oncogene signaling and pathways of RET signal transduction in the development of MEN 2 and MTC will allow new treatment possibilities.

Multiple endocrine neoplasia type 2: achievements and current challenges

Incremental advances in medical technology, such as the development of sensitive hormonal assays for routine clinical care, are the drivers of medical progress. This principle is exemplified by the creation of the concept of multiple endocrine neoplasia type 2, encompassing medullary thyroid cancer, pheochromocytoma, and primary hyperparathyroidism, which did not emerge before the early 1960s. This review sets out to highlight key achievements, such as joint biochemical and DNA-based screening of individuals at risk of developing multiple endocrine neoplasia type 2, before casting a spotlight on current challenges which include: (i) ill-defined upper limits of calcitonin assays for infants and young children, rendering it difficult to implement the biochemical part of the integrated DNA-based/biochemical concept; (ii) our increasingly mobile society in which different service providers are caring for one individual at various stages in the disease process. With familial relationships disintegrating as a result of geographic dispersion, information about the history of the origin family may become sketchy or just unavailable. This is when DNA-based gene tests come into play, confirming or excluding an individual's genetic predisposition to multiple endocrine neoplasia type 2 even before there is any biochemical or clinical evidence of the disease. However, the unrivaled molecular genetic progress in multiple endocrine neoplasia type 2 does not come without a price. Screening may uncover unknown gene sequence variants representing either harmless polymorphisms or pathogenic mutations. In this setting, functional characterization of mutant cells in vitro may generate helpful ancillary evidence with regard to the pathogenicity of gene variants in comparison with established mutations.