Testing the Safety and Efficacy of the Combination of Two Anti-cancer Drugs, ZEN003694 and Abemaciclib, for Adult and Pediatric Patients (12-17 Years) With Metastatic or Unresectable NUT Carcinoma, Breast Cancer and Other Solid Tumors

Required: NUTM1 ectopic expression

Ectopic expression of NUT protein per World Health Organization (WHO) criteria as determined by immunohistochemistry (IHC) testing

Required: NUTM1 gene translocation

Detection of the NUT gene translocation as determined by fluorescence in situ hybridization (FISH) testing

Required: NUTM1 gene translocation

Detection of the NUT gene translocation as determined by either deoxyribonucleic acid (DNA) next-generation sequencing (NGS) or ribonucleic acid (RNA) sequencing

Cannot have received: cytotoxic chemotherapy

Exception: must have recovered (CTCAE grade ≤ 1) from acute effects except for residual alopecia or grade 2 peripheral neuropathy

Patients who received chemotherapy must have recovered (CTCAE grade ≤ 1) from the acute effects of chemotherapy except for residual alopecia or grade 2 peripheral neuropathy

Cannot have received: radiotherapy

Exception: must have completed and fully recovered from acute effects; washout period of at least 14 days required between end of radiotherapy

Patients who received radiotherapy must have completed and fully recovered from the acute effects of radiotherapy. A washout period of at least 14 days is required between end of radiotherapy

Cannot have received: cytotoxic chemotherapy, immunotherapy, or other investigational therapy

Exception: within 2 weeks prior to entering the study

Participants who have had cytotoxic chemotherapy, immunotherapy, or other investigational therapy within 2 weeks prior to entering the study

Cannot have received: BET inhibitor therapy

Exception: two-week required washout period

There is a two-week required washout period for previous BET inhibitor therapy

Cannot have received: radiotherapy

Exception: within at least 2 weeks prior to entering the study. Stereotactic radiosurgery (SRS) within 1 week prior to entering the study will be allowed

Participants who have had radiotherapy within at least 2 weeks prior to entering the study. Stereotactic radiosurgery (SRS) within 1 week prior to entering the study will be allowed

Cannot have received: tyrosine kinase inhibitors (TKIs) or small molecules

Exception: within 5 half-lives or 1 week (whichever is shorter) of study entry

Participants who have received tyrosine kinase inhibitors (TKIs) or small molecules within 5 half-lives or 1 week (whichever is shorter) of study entry

Cannot have received: major surgery

Exception: within 3 weeks prior to entering the study

Participants who have had major surgery within 3 weeks prior to entering the study

Cannot have received: bone-targeted radionuclide

Exception: within 6 weeks of the first dose of ZEN003694

Patients who have had a bone-targeted radionuclide within 6 weeks of the first dose of ZEN003694