Rescue Plerixafor-based Mobilization and Outcomes of Salvage High-dose Chemotherapy in Relapsed/Refractory Germ Cell Tumors: A Large Single-center Experience.

BACKGROUND

High-dose chemotherapy (HDCT) with autologous peripheral blood progenitor cell (PBPC) support represents a potentially curative treatment for patients with relapsed/refractory germ cell tumors (GCTs). Plerixafor has demonstrated efficacy in improving CD34+ cell mobilization in hematologic malignancies, whereas evidence in solid tumors remains limited. Herein, we report a retrospective single-center experience with plerixafor-based rescue mobilization regimens in relapsed/refractory GCT patients eligible for salvage HDCT.

PATIENTS AND

METHODS

We retrospectively analyzed relapsed/refractory GCT patients treated at our Institution between September 2009 and August 2023 who underwent PBPC mobilization with plerixafor in combination with chemotherapy and granulocyte colony-stimulating factor. The primary endpoint was successful CD34+ cell collection. Secondary endpoints included number of leukapheresis procedures, feasibility of HDCT, and survival outcomes.

RESULTS

Twenty-two patients were included. All patients had poor-prognosis relapsed/refractory GCT and received a median of 2.5 prior treatment lines. Successful peripheral blood stem cell collection with plerixafor-based regimens was achieved in 19 of 22 patients (86%), with a median CD34+ collection of 4.9 × 106 cells/kg and a median of 2.3 leukapheresis procedures. Fifteen patients (68%) subsequently underwent HDCT; 8 patients completed all 3 planned HDCT cycles. After a median follow-up of 66.8 months, 7 of 15 patients (47%) remained continuously disease-free. Median time to neutrophil and platelet engraftment was 12.5 and 14.8 days, respectively.

CONCLUSION

Plerixafor-based rescue mobilization appears feasible and effective for CD34+ stem cell collection in heavily pretreated patients with relapsed/refractory GCTs. These findings support the role of plerixafor as a rescue mobilization strategy for these patients.