Disclosed herein are diagnostic and prognostic methods for determining the overall survival, and therapeutic regimes, for multiple myeloma patients. The methods involve the detection of PTHR1 gene expression alone or in combination with other clinical factors. The tests are suitable for diagnosing and monitoring treatment of patients having or suspected of having multiple myeloma. The disclosure also relates to proteasome inhibitors and other activators of PTHR1, for the treatment of multiple myeloma.
