Myelofibrosis and essential thrombocythemia are bone marrow disorders that disrupts your body’s normal production of blood cells. We are doing this study to find out whether an investigational drug called CPI-0610 can help with myelofibrosis or essential thrombocythemia. An investigational drug is a drug that is not approved for sale in the United States by the Food and Drug Administration (FDA).

This study has two groups (arms). One group of subjects will be treated with CPI-0610 alone (monotherapy arm), and the other group of subjects will be treated with CPI-0610 in combination with ruxolitinib (combination arm). CPI-0610 is a small molecule inhibitor of a group of proteins that are called BET proteins. By inhibiting (blocking) BET proteins from binding to certain cancer-causing genes, CPI-0610 may result in these genes being deactivated (switched off). CPI-0610 has shown anti-tumor activity in laboratory tests and animal studies. Ruxolitinib works by targeting proteins known as Janus kinases, or JAKs. When JAKs send too many signals, they cause the body to make the wrong number of blood cells. Ruxolitinib works by targeting JAKs, which control the production of blood cells. In doing so, ruxolitinib reduces overactive JAK signaling.