preg_replace

test.php

<?php             
$html = 
    "<div class=\"row home-pg-feed-item pl0 pr0 ml0 mr0\" data-type=\"video\">" .
        "<div class=\"col-lg-4 col-xs-4 pl0\">" .
            "<a href=\"/clinical-dialogue.php?v={{ url }}\"><img src=\"{{ thumb-sm }}\" alt=\"img\"/></a>" .
        "</div>" .
        "<div class=\"col-lg-8 col-xs-8 pr0 \">" .
            "<h4 class=\"mb5\">{{ title }}</h4>" .
            "<a href=\"/clinical-dialogue.php?v={{ url }}\" class=\"watch-link\">Watch the video</a>" .
            "<p>{{ summary }}</p>" .
        "</div>" .
    "</div>";

$item = array( "url" => "THEURL");
foreach($item as $key => $value){
   $html = str_replace("{{ " . $key . " }}", $value, $html);
}
echo $html;
?>