Tipzy (Testosterone Increase Post Zytiga): Increase In Serum Levels Of Testosterone (T) After Treatment Of Patients With Abiraterone Acetate (A) And Prednisone (P).

e17025Background: A is a high-affinity ligand of the enzyme CYP17. The binding of A to this enzyme produces a block in its activity, and lowers the concentration of precursor molecules of T, thus decreasing serum and intratumoral levels T. The extent of CYP17 inhibition must have inter-patient variability. Methods: Observational. Results: We found 10 patients in whom serum T levels, instead of decreasing after treatment with A, increase with time. All patients exhibiting TIPZy had been treated with ADT (Lupron or Zoladex) and 9/10 had PSAs 100 ng/dL within six months in some patients, plateauing. The highest level of TIPZy achieved was 180 mg/dL, seen in one patient, though increases in T to 100 ng/dL were not uncommon in this limited number of patients. However, there was no relationship between the rise in T and PSA: Patients with rising T...