Key Inclusion Criteria:

   1. Patients must be ≥ 18 years of age at the time of signing the informed consent form
   (ICF)

   2. The Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤ 2

   3. Patient must be a candidate for serial bone marrow aspirate and/or biopsy according to
   the institutions guidelines and must be willing to undergo a bone marrow aspirate.

   4. Patients must have one of the following for eligibility into the study:

      1. In dose optimization and expansion: IPSS-R defined very low, low or intermediate
      risk Myelodysplastic Syndrome (LR MDS) who failed to respond to or did not
      tolerate ESAs or luspatercept or HMAs and patients with del 5q who failed to
      respond to or did not tolerate lenalidomide; or

      2. In dose optimization and expansion: IPSS-R defined very low, low or intermediate
      risk Chronic Myelomonocytic Leukemia (LR CMML) who failed to respond to or did
      not tolerate hydroxyurea or HMAs.

Key Exclusion Criteria:

   1. Systemic antineoplastic therapy (including cytotoxic chemotherapy, alpha-interferon,
   kinase inhibitors or other targeted small molecules, and toxin-immunoconjugates) or
   any experimental therapy within 28 days or 5 half-lives, whichever is longer, and
   recovered from the toxicities before the first dose of study treatment. For patients
   that received antibodies the washout period is 4 weeks prior to study treatment.

   2. History of hypersensitivity to the study treatment or its excipients or to drugs of
   similar chemical classes.

   3. Patients who have previously been treated with agents that have the same mechanism of
   action as DFV890 as defined in Table 6-8, list of prohibited medications (e.g., drugs
   targeting the NLRP3 inflammasome pathway and the IL-1 pathway (canakinumab and
   anakinra)).

   4. Use of hematopoietic colony-stimulating growth factors (e.g., G-CSF, GM-CSF, M-CSF),
   thrombopoietin mimetics or erythroid stimulating agents anytime ≤ 1 week (or 5 half
   lives, whichever is longer) prior to start of study treatment.

   5. Patients receiving:

      1. concomitant medications that are known to be modulators of cytochrome P450
      enzymes CYP2C9 and/or CYP3A (specifically strong or moderate inducers of CYP2C9,
      strong inducers of CYP3A enzymes, strong inhibitors of CYP2C9 and/or strong or
      moderate dual inhibitors of CYP2C9/CYP3A); and

      2. patients, who are poor CYP2C9 metabolizers receiving concomitant medications
      known to be strong or moderate inhibitors of CYP3A, whose concomitant medications
      cannot be discontinued or switched to a different medication within 5 half-lives
      or 1 week (whichever is longer) prior to start of study treatment and for
      duration of the study. See Section 6.8 and list of prohibited drugs in Appendix 8
      for more details.

Other protocol-defined inclusion/exclusion criteria may apply.