$eventManager = \Bitrix\Main\EventManager::getInstance();
$eventManager->addEventHandler('', 'SearchTopOnBeforeUpdate', 'OnBeforeUpdate');
function OnBeforeUpdate(\Bitrix\Main\Entity\Event $event) {
$fields = $event->getParameter("SEARCH_CONTENT");
$result = new Entity\EventResult();
$result->modifyFields(array('TITLE' => 'test'));
return $result;
}