方琬云¹、石宏仁²、王百孚¹

彰化基督教醫院泌尿科¹；台北市立萬芳醫院泌尿科²

Wan-Yun Fang¹, Hung-Jen Shih², Pai-Fu Wang¹

Division of Urology, Changhua Christian Hospital, Taiwan¹

Division of Urology, Taipei Municipal Wanfang Hospital, Taiwan²

 

Purpose: Based on clinical practice and numerous studies, possible benefit was observed in metastatic castration resistant prostate cancer (CRPC) patients while abiraterone acetate plus prednisolone (AA+P) shift to abiraterone acetate plus dexamethasone (AA+D), which is known as “steroid switch (SS)”. The exact mechanism of SS was still not fully understood, and the famous SWITCH trail is still ongoing. In Asian countries, incidence and mortality rate were different from western countries. Although environmental factors play important roles, different genetic backgrounds were also one of most important reasons. This study reports a picture of SS in Asian patients.

Material and method: This is a retrospective study in Changhua Christian hospital. From July 2016 to February 2018, 11 patients, who had received AA+P after mCRPC status was confirmed, were enrolled in our study. A medication adjustment with SS was provided to these patients while biochemical and/or radiological progression was found. All characteristics were record, comprise previous treatment, PSA level, and image assessments. Progression free survival (PFS), including biochemical (b-PFS) and radiological PFS (r-PFS), was calculated as primary endpoint. Definition of PSA variation was according to COU-AA-301 study. A PSA decline 50% was defined as if it decreased over 25% but less or equal to 50% of baseline, a PSA decline 50% was defined as if it decreased over 50% of baseline. PSA progression was defined as a 25% increased of baseline.

Result: Median age was 70 years old, almost all patients (10 of 11, 91%) were found with metastatic prostate cancer at first diagnosis. One patient with lymph node metastasis and 9 have found bone metastasis. All 11 patients had regular hormone therapy and ever received chemotherapy with Taxotere, 6 of them ever had corticosteroid monotherapy and 3 patients had radiotherapy. Median time to CRPC was 33.96 months. Abiraterone acetate plus prednisolone were start given while progression biochemically or radiologically noted after chemotherapy. 9 patients had PSA decreased over 50%. Median time of abiraterone acetate plus prednisolone use was 5.93 months and median PSA level of beginning of SS was 24.38 ng/ml. There were 9 patients had PSA decreased over 50% and 2 patients did not. Biochemical progression during AA+P therapy was noted in 8 patients and radiological progression was found in 5 patients. 3 patients were found with disease progression in both way and 1 patient had no evidence of progression but received steroid shift due to poor biochemical response to AA+P. Steroid switch was offered for all patients after biochemical and/or radiological progression were found. Median duration of AA+D was 11.75 months. Median time to biological progression was 4.89 months and to radiological progression was 9.57 months. Only 5 patients had their PSA level decreased over 50% after steroid switch, and 1 patient had decreased PSA but less than 50%. There were 5 patients had poor or no response and elevating PSA after steroid switch. Three months biological progression-free survival rate was 63.64% and it became 36.36% at 6 months after steroid switch. Radio progression-free survival was 90.91% at 3 months and 72.73% at 6 months after steroid switch. Overall survival from steroid switch was 12.21 months, include 1 patient is still alive.

Conclusion: Steroid switch from prednisolone to dexamethasone use in abiraterone treatment may has a fair PSA level decline and fine radiological control in well-selected patients. There was still no clear recommendation or guideline to identify which patient may have well response after steroid switch or when to cease the therapy. Further molecular or prospective evaluations were needed. Until then, we should be careful and only use this kind of approach in PSA elevated, asymptomatic, with limited radiological progression patients.