H1B visa transfer pending

I am in a process of transfering my H1B visa from company A to B (I didn't do a premium application). I have already worked a few months for company B. I just got an offer from company C this week. Can I do the visa transfer from B to C when the transfer process from A to B is still in process? If I can, do I need to cancle the visa transfer petition from A to B before I start doing the transfer from B to C?
Will greatly appreciate your response.
Thanks.