High Doses of CD34+ Cells Chemomobilized with G-CSF PBPC Collection Had Greater CD34(+) Cells Collected Than G-CSF Alone and Trended toward Reduced Progression Rate after Autologous PBPC Transplantation for Breast Cancer in a Phase III Trial.

We evaluated intensive chemotherapy prior to PBSC mobilization vs. G-CSF alone for PBPC mobilization in a randomized controlled trial of 143 patients who received high dose chemotherapy with cyclophosphamide 6 g/m², thiotepa 750 mg/m² and BCNU 450 mg/m² over 3 days with PBSC support for treatment of breast cancer. 74 patients were randomized to chemomobilization with cisplatin 135 mg/m², etoposide 1200 mg/m², and cyclophosphamide 4.5 g/m² over 3 days plus G-CSF (6mcg/kg q12h)(CVP-G), while 69 patients received G-CSF alone with the collection goal >4 x 10⁶ CD34(+) cells/kg. 77 patients were stage II–III, 66 were stage IV. The CVP-G group had improved mobilization with a collection of 18 (range 3–141) x 10⁶ CD34(+) cells/kg compared with 4(2–13) x 10⁶/kg for the G-CSF group (p<0.001). Granulocyte and platelet recovery post-transplant was 9/9 days for the CVP-G mobilized group, 10/11 days for the G-CSF group (p<0.001). Actuarial risk of progression at 6 years in patients mobilized with CVP-G was 59±7% vs. 66±6% for G-CSF alone (p=0.2). Rate of progression post-transplant was evaluated according to quantities of collected CD34(+) cell dose [for CVP-G, first quartile ≤ 9.0, second ≤17, third ≤40, and fourth >40]. Only one patient in the G-CSF alone group collected >9 x 10⁶ CD34(+) cells. In the CVP-G group progression trended toward being reduced in patients with CD34(+) cell doses collected of >9 x 10⁶/kg (57±9% vs. 65±11%, p=0.06) This effect was consistent for all stages. Overall survival was improved in the CVP-G patients collecting ≥9 x 10⁶ CD34(+)/kg 62±7% vs. 27±11% those collecting less. For patients receiving CD34(+) doses ≤9 x 10⁶/kg, the progression rate was 65±11% in the CVP-G group and 68±6% in the G-CSF group (p=NS). Higher doses of CD34(+) cells collected by chemomobilization than G-CSF alone and those patients with the higher doses of CD34(+) collected trended toward lower disease progression after high dose chemotherapy.