I think it's important to note that although biological systems are still well out of our reach, chemical systems (using quantum chemical methods) is being done

I think it's important to note that although biological systems are still well out of our reach, chemical systems (using quantum chemical methods) is being done increasingly better, and we can learn a lot about various systems, ranging from graphene to organic semiconductors to metal-clusters in enzymes using computational methods. So one day, we'll slowly get there, and we shouldn't write it off. Though yes, the current state of the art is hopeless for cancer drug development--but the field is dynamically changing.