The National Research Council has explained that:
“Precision Medicine refers to the tailoring of medical treatment to the individual characteristics of each patient. It does not literally mean the creation of drugs or medical devices that are unique to a patient, but rather the ability to classify individuals into subpopulations that differ in their susceptibility to a particular disease, in the biology or prognosis of those diseases they may develop, or in their response to a specific treatment.”
WIKIPEDIA accessed 8/17/2020
National Research Council (US) Committee on A Framework for Developing a New Taxonomy of Disease. Toward Precision Medicine: Building a Knowledge Network for Biomedical Research and a New Taxonomy of Disease. Washington (DC): National Academies Press (US); 2011. PMID: 22536618. Appendix E. Glossary. Precision Medicine
“Precision” treatments—ones that might work better in a particular subpopulation--still need to be studied to see if they do work better in a particular subpopulation. Some of these studies might involve use of a placebo.
There are, however, some (a few) “precision” treatments that have been developed to treat a single patient. A good account of the development of a precision treatment for a single patient is given in a lay journal.
The case is also described in publication in the medical literature.
In this instance, the drug to treat a rare condition was identified and tested in this patient in a study called an N-of-1 study. That is, the drug was tested in this and only this patient. The patient improved on the treatment. This N-of-1 study did not involve use of a placebo.
So the answer to your question is “Yes, it is possible (sometimes) to eliminate the use of a placebo when evaluating a treatment that has been developed based on the principles of precision medicine.”
Note that this patient improved but was not cured by this truly precision treatment. Precision medicine does not always cure a patient.