Pyrido[2,3-b]pyrazin-8-substituted compounds and their use

A method of inhibiting the progress of, reducing the rate of progress of, alleviating a symptom of, or ameliorating cancer comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound of the following formula, or a pharmaceutically acceptable salt thereof:

• wherein:
• —RPH1 is independently —F or —SMe;
• and
• —RPY1 is independently phenyl or pyridyl, and is optionally substituted with one or more substituents selected from —F, —Cl, —Br, —I, —R5, —OH, —OR5, —CF3, —OCF3, wherein each —R5 is independently saturated aliphatic C1-4alkyl;
• and wherein the cancer is:
• thyroid cancer;
• melanoma (including malignant melanoma);
• lung cancer (including non-small cell lung cancer and small cell lung cancer);
• colorectal cancer;
• pancreatic cancer;
• sarcoma;
• gastrointestinal cancer;
• ovarian cancer;
• lymphoma;
• leukemia;
• skin cancer;
• testicular cancer;
• prostate cancer;
• a carcinoma of the cervix;
• bladder cancer;
• breast cancer;
• liver cancer;
• kidney cancer;
• stomach cancer;
• endometrial cancer;
• seminoma;
• a hematopoietic tumor of myeloid lineage;
• myelodisplastic syndrome;
• a carcinoma of the oesophagus;
• brain cancer;
• glioma;
• bone cancer;
• or
• squamous cancer.