Comment by SemanticStrengh

Most of the scientific problems (diseases, quantum gravity, etc) have been resolved, it's just that no one knows it. Because researchers are paid to produce new papers, but nobody is paid to extensively read the ocean of existing papers.

Cancer? PNC-27 + thymalin

Ageing? Skq1 + Epitalon

Quantum gravity? https://arxiv.org/pdf/gr-qc/9706055.pdf