Inclusion Criteria:  Histologically confirmed advanced or metastatic solid tumor indicated below that is relapsed, refractory, or intolerant to available therapies with known benefit:  Sarcomas of any histology Castrate resistant prostate cancer ER Positive Breast Cancer and Triple Negative Breast Cancer Solid tumors with known MYC amplification Must have measurable disease; patients with breast and prostate cancer may have evaluable disease Eastern Cooperative Oncology Group (ECOG) Performance Score of 0 or 1 Adequate organ function Must provide tumor tissue sample to the central laboratory for biomarker analysis Must have recovered from the effects of any prior cancer related therapy, radiotherapy, or surgery (toxicity no greater than Grade 1)  Exclusion Criteria:  Primary malignancies of the CNS, or uncontrolled CNS metastases, including impending spinal cord compression Prolonged QT interval Treatment with strong inhibitors or inducers of CYP3A4 Prior exposure to a CDK9 inhibitor  History of another malignancy except for:  Curatively treated malignancy with no known active disease Curatively treated non-melanoma skin cancer or lentigo maligna without evidence of disease Curatively treated carcinoma in situ without evidence of disease