860PIMPACT OF RESPONSE TO INDUCTION CHEMOTHERAPY IN PATIENTS WITH GERM CELL TUMORS (GCT) RECEIVING SALVAGE HIGH-DOSE CHEMOTHERAPY (HDCT): A STUDY OF THE EBMT SOLID TUMORS WORKING PARTY (STWP)

ABSTRACT Aim: HDCT has a recognized indication in the salvage setting of advanced GCT and is steadily utilized worldwide. While the prognostic impact of response to prior lines of CT is ascertained, that of response to induction/mobilization CT preceding single or multiple HDCT cycles is unknown. We present the results of a retrospective study of the EBMT-STWP. Methods: Data have been collected from 16 European centers. Eligibility included adult male patients (pts) with GCT, and treatment with second or further-line HDCT between the years 2002 and 2012. Distribution of frequencies were compared between the years Results: Since 10/2013, 313 pts have been registered. All pts mobilized with GCSF (26 [8%] with GCSF only). 21 mobilization regimens were used, including 11 platinum-based CT. 13 different HDCT regimens were administered as single (n = 74), double (n = 102), or multiple (n = 137) courses. A stepwise harmonization of HDCT regimens was observed, and carboplatin-etoposide (CE) was more frequent in recent years (40.8 vs 73.8%). 45 pts (14%) had a progression to induction, 231 (74%) a response (11 missing and 26 GCSF only). In the multivariable model for PFS, mediastinal primary (HR: 2.32, 95%CI, 1.08-4.96, p = 0.042), IGCCCG poor prognostic category (HR: 1.76, 95%CI, 1.08-2.84, p = 0.048), and progression to induction (HR: 1.93, 95%CI: 1.27-2.93, p = 0.008) were significantly prognostic. The latter was the only significant prognostic factor for OS (HR: 2.46, 95%CI, 1.54-3.91, p Conclusions: Response to induction CT prior to HDCT was independently and significantly associated with PFS and OS, while response or progression to prior CT lines was not. This information could have important implications to refine patient eligibility to transplantation in this disease. These data need external validation. Disclosure: All authors have declared no conflicts of interest.