Best way to replace/remove a specific character when it appears between 2 character sequences

I have a php function which selects the text from a string between 2 different character sequences.

function get_string_between($string, $start, $end){
    $string = ' ' . $string;
    $ini = strpos($string, $start);
    if ($ini == 0) return '';
    $ini += strlen($start);
    $len = strpos($string, $end, $ini) - $ini;
    return substr($string, $ini, $len);
}

$fullstring = ',""Word1, Word2""';
$parsed = get_string_between($fullstring, ',""', '""');

echo $parsed; //Result = Word1, Word2

However, I would like to extend this further to select all matches when there are multiple occurrences within the string (this is likely, since the string will be generated by a csv file with hundreds of lines and hundreds of matches.) For example:

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';

And within each substring I will need to remove certain characters. In this example, I need to remove commas.

Can anybody suggest the most straightforward way of achieving this? Thanks.