Folate hydrolase-1 (FOLH1) is a novel target for antibody-based brachytherapy in Merkel cell carcinoma.

BACKGROUNDS: Folate Hydrolase-1 (FOLH1; PSMA) is a type II transmembrane protein, luminally expressed by solid tumour neo-vasculature. Monoclonal antibody (mAb), J591, is a vehicle for mAb-based brachytherapy in FOLH1+ cancers. Brachytherapy is a form of radiotherapy that involves placing a radioactive material a short distance from the target tissue (e.g., on the skin or internally); brachytherapy is commonly accomplished with the use of catheters, needles, metal seeds and antibody or small peptide conjugates. Herein, FOLH1 expression in primary (p) and metastatic (m) Merkel cell carcinoma (MCC) is characterized to determine its targeting potential for J591-brachytherapy. MATERIALS & METHODS: Paraffin sections from pMCC and mMCC were evaluated by immunohistochemistry for FOLH1. Monte Carlo simulation was performed using the physical properties of conjugated radioisotope lutetium-177. Kaplan-Meier survival curves were calculated based on patient outcome data and FOLH1 expression. RESULTS: Eighty-one MCC tumours were evaluated. 67% (54/81) of all cases, 77% (24/31) pMCC and 60% (30/50) mMCC tumours were FOLH1+. Monte Carlo simulation showed highly localized ionizing tracks of electrons emitted from the targeted neo-vessel. 42% (34/81) of patients with FOLH1+/- MCC had available survival data f or analysis. No significant differences in our limited data set were detected based on FOLH1 status (p = 0.4718; p = 0.6470), staining intensity score (p = 0.6966; p = 0.9841) or by grouping staining intensity scores (- and + vs. ++, +++, +++) (p = 0.8022; p = 0.8496) for MCC-specific survival or recurrence free survival, respectively. CONCLUSIONS: We report the first evidence of prevalent FOLH1 expression within MCC-associated neo-vessels, in 60-77% of patients in a large MCC cohort. Given this data, and the need for alternatives to immune therapies it is appropriate to explore the safety and efficacy o f FOLH1-targeted brachytherapy for MCC.

[Lynch Syndrome -  the Pathologist's Diagnosis]. / Diagnóza Lynchova syndromu od patologa.

Lynch syndrome (formerly known as hereditary non-polyposis colorectal cancer) is the most com-mon hereditary colorectal cancer syndrome. The syndrome is caused by a germline mutation of one of the mismatch repair (MMR) genes responsible for DNA replication error repair. Impaired function of the proteins encoded by these genes leads to microsatellite instability (MSI), which is associated with increased incidence of neoplasms: mainly colorectal cancer. According to recent estimates, up to 5% of all colorectal cancers are associated with Lynch syndrome. Due to this relatively high frequency, familial occurence, absence of premorbid phenotype, and development of malignant tumors at a reproductive age, a correct diagnosis is important not only from an ethical but also from an economical point of view. Unfortunately, clinical means of diagnosis, namely, the revised Bethesda guidelines designed to detect patients suitable for genetic testing for Lynch syndrome, lack sufficient sensitivity. The methods associated with modern pathology are more sensitive than the clinical criteria used to detect patients suspected of having Lynch syndrome. Pathological diagnostics are based on direct or indirect detection of MSI. Indirect methods include analysis of morphological signs associated with MSI in histological samples from colorectal carcinoma patients and immunohistochemical investigation of MMR protein expression. To rule out sporadic cases caused by epigenetic inactivation of an MMR gene, molecular genetic investigation of the BRAF gene and methylation analysis of the MLH1 promoter are performed during diagnostic workup. A suspicion of Lynch syndrome based on the results of the methods mentioned above should be proven by detection of a germline mutation in an MMR gene in peripheral blood leukocytes.

[Muir-Torre syndrome--a phenotypic variant of Lynch syndrome]. / Muir-Torre syndrom--fenotypická varianta Lynchova syndromu.

Muir-Torre syndrome (MTS) represents an autosomal dominantly inherited condition and is considered a phenotypic variant of the more common hereditary nonpolyposis colorectal cancer syndrome (HNPCC), or Lynch syndrome. MTS combines at least one cutaneous neoplasm with sebaceous differentiation (e.g. sebaceoma, sebaceous adenoma, and sebaceous carcinoma), and at least one visceral malignancy. MTS is a genetic disorder caused by a germline mutation in one of the DNA mismatch repair (MMR) genes. Tumors in MTS patients are characteristically associated with the loss of MMR protein expression and/or microsatellite instability (70%). Patients who are suspected to have MTS/Lynch syndrome are often identified by dermatologists, dermatopathologists/pathologists, gastroenterologists and gynecologists. If MTS is suspected on a clinicopathological ground, necessary additional laboratory investigations should be performed only in specialized pathological departments providing immunohistochemistry and molecular biologic analysis service.