How did that come about?

I got a meeting with your CEO this afternoon about a potential collaboration.

   That sounds exciting. How did that come about?

How did that come about?

(どういう経緯、きっかけででそうなったの？)

come about   物事が起こる、生じる

How did this problem come about?

How did it come about that you moved to Tokyo? 

(どういういきさつで東京に引っ越すことになったの？）

どうしてそう/こうなったの？

How did that/this happen?