Key Inclusion Criteria (Phase 1):

        - Confirmed hematologic malignancy, including Acute Myeloid Leukemia (AML), Chronic
        Lymphocytic Leukemia (CLL), Chronic Myelogenous Leukemia (CML), Acute Lymphocytic Leukemia
        (ALL), Myelodysplastic Syndrome (MDS), Multiple Myeloma (MM), Myelofibrosis (MF),
        Myeloproliferative Neoplasms (MPN) or MDS/MPN overlap diseases. (Once Phase 2 has started
        subjects with AML will be eligible for inclusion in the Phase 1 portion of the study only
        if their malignancy has been shown to have c-Cbl mutation, trisomy 3, trisomy 11, inv(16),
        or elevated FLT3. [Other AML and subjects with MDS will no longer be eligible for inclusion
        in the Phase 1 portion of the study]).

        Key Inclusion Criteria (Phase 2):

          -  Part A: AML or MDS patients with an acceptable level of EphA3 expression

          -  Part B: MF patients with an acceptable level of EphA3 expression

        Key Inclusion Criteria (Both Phases):

          -  Confirmed hematologic malignancy refractory to or progressed following standard
             treatments, or subjects not considered medically suitable to receive standard of care
             treatment or who refuse standard of care treatment

          -  Acceptable level of EphA3 expression

          -  Eastern Cooperative Oncology Group (ECOG) ≤1

          -  Acceptable laboratory results

        Key Exclusion Criteria (Both Phases):

          -  For subjects with AML, more than 2 prior therapies for AML (induction and
             consolidation with or without a hypomethylating agent given in a maintenance setting
             are considered 1 therapy)

          -  History of or current central nervous system (CNS) involvement that may increase risk
             of bleeding

          -  Recent major surgery

          -  Ongoing surgical or wound healing complications

          -  Active clinically significant bleeding

          -  Uncontrolled hypertension

          -  Significant intercurrent illness

          -  Known history of prolonged bleeding times or platelet dysfunction

          -  Active infection requiring IV antibiotics, IV antifungals, or IV antivirals within 2
             weeks prior to Cycle 1, Day 1