Pharmacokinetics and Safety Study of Pelabresib in Patients With Advanced Malignancies and Hepatic Impairment

This study consists of 2 main parts: Part 1 will assess the PK characteristics of pelabresib in participants with hepatic impairment versus normal hepatic function, and during Part 2, extended treatment with pelabresib may be offered in case of clinical benefit, as assessed by the investigator. A participant is considered to have started the study and entered the screening period upon signing the informed consent form (ICF). Enrollment occurs when participant receive their first dose of study treatment via the IRT system. A participant is considered to have completed the study if they have completed all phases of the study including the end of treatment (EOT) and 30-day safety follow-up visits. Participants with hematological malignancies will be followed up every 3 months beyond EOT. Part 1: Impact of hepatic impairment on pelabresib PK In Part 1, the PK characteristics of pelabresib will be investigated in participants with advanced malignancies comprising 2 different study groups according to their hepatic function: * Group 1 includes participants with normal hepatic function * Group 2 includes participants with moderate or severe HI Following completion of Part 1, participants can directly proceed to Part 2 Part 2: Continued treatment After completing Part 1, in case of clinical benefit, participants can continue with pelabresib treatment in Part 2 until the end of study (EOS) is reached, until the participant meets discontinuation criteria, or until they receive pelabresib treatment via alternative means of access, whichever occurs first. Clinical benefit is determined by the investigator. End of treatment visit An EOT visit is required for all participants within 7 days of the last dose of pelabresib treatment (or within 7 days of the decision to discontinue treatment, if the decision was made \> 7 days after the last dose). 30-day safety follow-up All participants will be followed up for AEs and serious AEs (SAEs) for 30 days (±3 days) following the last dose of pelabresib. If the participant starts another anticancer treatment or switches to pelabresib treatment via an alternative source (e.g., in an extension study or commercially available pelabresib), the safety follow-up will end at the time of the first administration of the respective treatment. Leukemic transformation follow-up for participants with hematological malignancies After the EOT visit and the 30-Day safety follow-up visit, participants with hematological malignancies will be followed up every 3 months for leukemic transformation until the overall end of the study, confirmation of AML, withdrawal of consent, loss to follow-up, or death, whichever occurs first.