ADAL - JavaScript used in Angular JS in SPA app , to call third party APIs exposed through APIGEE giving CORS error

I have created a SPA and used Azure AD for User store and ADAL-JavaScript library as mentioned on a http://ift.tt/1tNCMOM to integrate with my angular js code. It did authentication flow successfully, but when I was calling the third party API exposed using APIGEE, I was getting following error messages:

Failed to load resource: the server responded with a status of 502 (Bad Gateway)

XMLHttpRequest cannot load http: //webapiexposedusingapigee. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://mywebsite.in' is therefore not allowed access. The response had HTTP status code 502.

When I checked in Fiddler i got following fault string. "faultstring=Received 405 Response without Allow Header"

and warning as :

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http:// http://ift.tt/1zgwh7e. This can be fixed by moving the resource to the same domain or enabling CORS.

I had added following headers on APIGEE:

 <Header name="Access-Control-Allow-Origin">*</Header>
            <Header name="Access-Control-Allow-Credentials">true</Header>
            <Header name="Access-Control-Allow-Headers">Origin, X-Requested-With, Content-Type, Accept</Header>
            <Header name="Access-Control-Max-Age">3628800</Header>
            <Header name="Access-Control-Allow-Methods">GET, PUT, POST, DELETE, OPTION</Header>

Any help on this is appreciated.

Thanks.