H1B petition in RFE response review for 160 days.Advise on wt can be dne?

H1B petition is in RFE response review for more than 160 days now. Any suggestions on what can be done? RFE response was received by USCIS on 16th Oct 2012, still there are no updates. Is there any reason for this status? When will USCIS complete processing for all petitions received?