# Current Status, Issues and Future Prospects of Personalized Medicine for Each Disease
## 5 Discussion  
We conducted a comparison for each disease, focusing on factors that may influence personalized medicine. As the comparison object of the disease, we cited the oncology area, where personalized medicine is most advanced, and SMA, one of the rare diseases where nucleic acid drugs and gene therapy approaches have been developed in recent years (Table 1). For the oncology area, many molecular-targeted drugs have been developed and marketed in recent years, and it is becoming possible to select more effective anticancer drugs by diagnosing the presence or absence of protein expression and gene abnormalities for each patient. For many molecularly targeted drugs, diagnosis related to the mechanism of action of each drug allows stratification of patients who can or cannot be expected to benefit, and it is currently considered to be the disease area where personalized medicine is most prevalent. Furthermore, the high cost of treatment and the high number of side effects are also thought to contribute to the spread of personalized medicine. Similarly, in the rare diseases area, personalized medicine is advancing for diseases for which the causative genes and diagnostic methods have been clarified by the technological advances in nucleic acid drugs and gene therapy. In the case of SMA, the use of Spinraza or Zolgensma for treatment is based on the presence or absence of the target gene mutation, so testing for the presence of the gene mutation is a necessity. Nucleic acid drugs and gene therapeutics are not readily available without diagnostic testing for the disease due to high manufacturing costs. Therefore, diagnostic tests are mandatory for the treatment of such diseases, and the drugs are used only in the patient population where they are expected to be effective. Nucleic acid drugs and gene therapy drugs can be considered as modalities for which personalized medicine is essential. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Item** & **Cancer** & **Rheumatoid Arthritis** & **Foreiasis** & **Alzheimer’s Disease** & **Spinal Muscular Atrophy (SMA)** \\ \hline Understanding of Disease & Somatic mutation of driver & autoimmune disease, & autoimmune disease, & & \\ MOA & genes (monogenic) & polygenic & polygenic & polygenic & SMN1 gene \\ \hline \multirow{2}{*}{Diagnostic markers(test)} & numerous & & & PET & \\  & (Oncope panel tests) & RE, ACPA & - & (A\(\Phi\)42/A\(\Phi\)40, tau, Neurodegeneration) & SMN1 gene mutation \\  & (Oncope panel tests) & & & & Neurogeneration) \\ \hline \multirow{4}{*}{Drug (CDs)} & Herceptin (HRE2) & & & & \\  & Gefitinib (EGFR) & & & & \\  & Imatinib (BCL-Lab) & - & - & - & (Anti-AAV) \\ \cline{1-1}  & Citicitinib(LK fusion) & & & & \\ \cline{1-1}  & Nivolumab (PD-1, MSI) etc. & & & & \\ \hline Treatment satisfaction & Low-medium & medium & medium & low & low-medium \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of items related to personalized medicine for each disease. For RA area, molecular-targeted drugs have become popular in recent years, and various types of therapeutic agents, including biologics, have become available. Drugs that slow the progression of the disease, so-called DMARDS (disease-modified anti-rheumatic drugs), are the mainstream, and antibody drugs that neutralize the effects of cytokines that cause inflammation and block their inflammatory signal pathways are now available. However, for each drug, their therapeutic efficacy and side effects vary among patients, and no predictive diagnostic marker has been able to be developed (Figure 1A). The FDA's Table of Pharmacogenomic Biomarkers in Drug Labeling also provides limited information in the RA [76]. Guidelines recommend the use of RF and ACPA as diagnostic markers of poor prognosis in rheumatoid arthritis, and they are used as indices for the selection of therapeutic agents.