'DAX SUMMARIZECOLUMNS FILTER NOT IN or DOES NOT CONTAIN

I am writing a DAX query, and trying to filter out values that contain the word "OPEN" 

EVALUATE
SUMMARIZECOLUMNS (
    Salesforce[SalesPersonName],
    FILTER ( 'Salesforce', Salesforce[SalesPersonName] <> "OPEN" )
)


Solution 1:[1]

Have you tried using CONTAINSSTRING?

EVALUATE
SUMMARIZECOLUMNS (
    Salesforce[SalesPersonName],
    FILTER (
        'Salesforc`enter code here`e',
        NOT ( CONTAINSSTRING ( Salesforce[SalesPersonName], "OPEN" ) )
    )
)

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Angelo Canepa