How to access specific Element in Nested JSON Array in PHP?

I have a very large JSON file output from an API which has so many nested child elements, I have been trying to figure out a way to access only specific ones but it has been a total chaos and I finally gave up and came here looking for help.

here's what API return looks like:

{
    response: {
        errors : [],
        messages : [],
        results: {

            candidates : [
                {
                  count:{
                    from: 0,
                    to: 39,
                    total: 77,
                    },
                    officials: [
                        {
                            id: 10001,
                            first_name: John,
                            last_name: Doe,
                            office: {
                                id: 50001,
                                title: Head Office
                            }
                        },
                        {
                            id: 10002,
                            first_name: Mike,
                            last_name: Arthur,
                            office: {
                                id: 50005,
                                title: Secondary Office
                            }
                        },
                    ]
                }
            ] 
        
        }
    }
}

PHP Code:

$request = wp_remote_get( 'MY URL' );

if( is_wp_error( $request ) ) {
    return false; // Bail early
}

$body = wp_remote_retrieve_body( $request );

$data = json_decode( $body, JSON_PRETTY_PRINT );

if( ! empty( $data ) ) {

    foreach( $data['response']['results']['candidates']['officials'] as $item) {
        echo $item['last_name'];
    }

}

I have also tried following:

$request = wp_remote_get( 'MY URL' );

if( is_wp_error( $request ) ) {
    return false; // Bail early
}

$body = wp_remote_retrieve_body( $request );

$data = json_decode( $body, JSON_PRETTY_PRINT );

if( ! empty( $data ) ) {

    foreach( $data-response-results-candidates-officials as $item) {
        echo $item['last_name'];
    }

}

Tutorial source

Both solutions gives null.

What I need to get is only First Name Last Name of the candidate.

Thanks in advance :)