Strategic considerations

Acute myeloid leukemia (AML) is the second most common type of leukemia diagnosed in adults and children, but most cases occur in adults. This study is to evaluate how safe ABBV-787 is and how it moves within the body in adult participants with relapsed/refractory (R/R) acute myeloid leukemia (AML). Adverse events and maximum tolerated dose (MTD) of ABBV-787 will be assessed.

ABBV-787 is an investigational drug being developed for the treatment of AML. Participants will receive ABBV-787 in escalating doses until the maximum tolerated dose (MTD) is determined. Approximately 60 adult participants with a diagnosis of AML will be enrolled worldwide.

Participants will receive intravenous (IV) infusions of ABBV-787 during the approximately 3 year duration a participant is followed.

There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests and checking for side effects.

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Laboratory Criteria matching those outlined in the protocol.
• QT interval corrected for heart rate (QTc) <= 470 msec using Fridericia's correction, and no other clinically significant cardiac abnormalities.
• Documented diagnosis of non-promyelocytic acute myeloid leukemia (AML), per 2022 European Leukemia Net (ELN) criteria.
• Participants with relapsed/refractory (R/R) acute myeloid leukemia (AML) who have been treated with up to 3 prior lines of therapy and are refractory to or intolerant of all established AML therapies that are known to clearly provide clinical benefit at the judgement of the investigator.
• Must have a white blood cell (WBC) count < 25 × 10^9 /L prior to initiation of study drug (Note: Hydroxyurea or leukapheresis is permitted to meet this criterion and for use through Cycle 3 to control for hyperleukocytosis.).

Exclusion Criteria:

• Have received a CD33-targeting therapy within 3 months prior to the first dose of ABBV-787.
• Stem cell transplant within 3 months prior to first dose of study drug.
• Have received anticancer therapy including chemotherapy, radiation therapy, immunotherapy, biologic, or any investigational therapy within 14 days or 5 half-lives of the drug (whichever is shorter) prior to the first dose of ABBV-787.
• History of documented pneumonitis that required treatment with systemic steroids within the last 6 months, nor any evidence of active pneumonitis.
• Unresolved toxicity of Grade >= 2 from prior anticancer therapy, or to levels dictated in the eligibility criteria, with the exception of alopecia.
• Known active severe or poorly controlled acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.