This study is being initiated to provide continued access to GS-9137/r for those subjects currently benefiting from their participation in an ongoing GS-9137/r study. This study will also provide initial access to GS-9137/r for those subjects who have completed a GS-9137/r study in which the subject was participating in a treatment arm that did not include GS-9137/r. This study will continue to monitor the safety and tolerability of GS-9137/r through periodic assessment of adverse events, changes in concomitant medications and clinical laboratory tests. This study is an open-label study.