You are being asked to consider participating in this study because you have been diagnosed with myelofibrosis (MF) and your prior treatment with a JAK Inhibitor is not effective enough or has become ineffective.

This is the first study of KRT-232 in MF and it will evaluate how well tolerated KRT-232 is when given to participants with MF, and whether KRT-232 can improve your MF. KRT-232 has been given to about 253 participants with different cancers and disorders (other than MF).
KRT-232 is a small molecule inhibitor and can reverse a mechanism through which unhealthy or tumor cells can survive and grow. This study will test if KRT-232 can restore the function of your healthy bone marrow cells and reduce the symptoms of your MF.

There are 2 parts planned for this study, Part A will test different doses and schedules of KRT-232 in 4 groups of participants to identify the recommended dose and schedule for Part B. Part B will continue to test if the recommended dose and schedule is a tolerable and effective treatment for MF.

If you consent to this research study, you will participate only in Part A. Currently Groups 1, 2, and 3 in Part A have completed enrollment. Therefore, if you have not already been assigned to a Group prior to signing this form, you will be assigned to Cohort 4b