When patients reach their individual MTD (either at 10 weeks or earlier) they will return to the site 3-7 days after for an End of Treatment Phase assessment to be evaluated for safety and, optionally, a PK assessment. Subsequent to the End of Treatment Phase visit patients will be instructed to begin down-titration off of BPS-MR in weekly increments. However, patients may alternatively elect to continue taking BPS-MR at their MTD in a separate open-label extension study.