Regarding H1B transfer of the pending petition

i have never been to US and currently working for the company A in India and have got the approved visa stamped on my passport and valid petition that will be expired in Dec-2013. I wanted to join in company B and comany B has started the premius visa transfer process. I have got the RFE for the same. Meanwhile, my current employer (Company A) is asking me to travel to US immediately.

My question is, Is it allowed to travel to US in the present situation i.e with the company A’s visa to work for company A itself while the company B’s visa petittion is in pending ( yet to respond to RFE)? Appreciate quick response. Plz help me.