Try
/^[^,-]+/
i.e. in JavaScript
"one two three".match(/^[^,-]+/); //["one two three"]
"one, two three".match(/^[^,-]+/); //["one"];
[EDIT, in response to OP's comment about new requirement]
To match only if the letter 'm' is found somewhere in the string:
"one two m th,ree".match(/^(?=[\s\S]*m)[^,-]+/); //["one two m th"]
"one two th,ree".match(/^(?=[\s\S]*m)[^,-]+/); //null