Plerixafor Plus G-CSF for CD34+ Cell Mobilization Offers Benefits Compared with Chemotherapy Plus G-CSF

Although studies have shown plerixafor (Mozobil) plus granulocyte-colony stimulating factor (G-CSF) mobilizes more CD34+ cells than G-CSF alone prior to autologous hematopoietic stem cell transplant, many patients receive chemotherapy followed by G-CSF to mobilize CD34+ cells before transplantation. In a poster session presented at the 51st ASH Annual Meeting, Paul J. Shaughnessy, MD, medical director, Adult Blood and Marrow Transplant, Texas Transplant Institute, San Antonio, Texas, reported the results of a retrospective study that found plerixafor plus G-CSF mobilization resulted in more predictable days of collection, no weekend apheresis procedures, and no unscheduled hospital admissions compared with chemotherapy plus G-CSF. The study also found that the plerixafor regimen had similar costs to the chemotherapy regimen because the acquisition costs of plerixafor were offset by using less G-CSF and resources.

Patients and Methods

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Dr Shaughnessy and colleagues’ study included 34 patients with multiple myeloma (n = 20) or non-Hodgkin lymphoma (NHL) who had participated in the expanded access program (EAP) of plerixafor plus G-CSF for upfront mobilization of CD34+ cells. Researchers compared the costs of mobilization and clinical outcomes for these patients to 34 matched historical controls with multiple myeloma (n = 20), NHL (n = 13), or Hodgkin lymphoma (n = 1) who were mobilized with chemotherapy and G-CSF at the Texas Transplant Institute (n = 9) and the Rocky Mountain Blood and Marrow Transplant Institute, Denver, Colorado (n = 25). Control patients were well matched for age, sex, disease stage, and number of prior therapies. These patients received 3 to 5 gm/mof cyclophosphamide followed by daily G-CSF, whereas study patients received 10 mcg/kg of G-CSF daily for 5 days and 0.24 mg/kg of plerixafor on the evening of day 4, between 10 and 11 hours before the initiation of apheresis the next day. This regimen was repeated daily for up to 4 additional apheresis or until a minimum of 2 x 10⁶ CD34+ cells/kg were collected. Although apheresis was scheduled for 5 days after starting G-CSF in the study patients and 10 days after starting G-CSF in the control patients, the actual start of apheresis was based on peripheral blood CD34+ cell counts of ≥10/µL.

Mobilization procedure costs were calculated using median national reimbursement rates from the Centers for Medicare and Medicaid Services (CMS). They comprised the costs of mobilization procedures, hospitalization, provider visits, apheresis, CD34+ cell processing, and cryopreservation. Medication costs related to mobilization were calculated using the average sale price and comprised costs for G-CSF, plerixafor, cyclophosphamide (Cytoxan), mesna (Mesnex), antiemetics, and antimicrobials.

Study Findings

All patients received an autologous hematopoietic stem cell transplant with no difference in median time to absolute neutrophil count or platelet engraftment. The median costs of mobilization were similar between the groups, with a median cost of $19,644.66 in the study group compared with $18,831.26 for historical controls. Two patients in the control group experienced neutropenic fever after receiving cyclophosphamide during the mobilization period and were hospitalized. The majority of study patients (79%) started apheresis on the scheduled day compared with just over half (53%) of control patients (P = .021), and 17 control patients (50%) underwent weekend apheresis secondary to unplanned starts. Because CMS’ national reimbursement data do not differentiate between the costs of weekend or weekday apheresis or flow cytometry, no difference in costs for weekend procedures was reflected in the cost data analysis. Study patients received a median of one dose of plerixafor (median 16.9 mg), which had an average sales price of $6,250 per 24-mg vial. Despite this additional cost for study patients, there was a nonsignificant difference in total cost of mobilization for the two groups. Based on these results, Dr Shaughnessy and colleagues concluded that further prospective studies comparing plerixafor plus G-CSF to chemo mobolization are warranted.

Take-home Message for Practicing Oncologists

When asked in an interview with Oncology Net Guide and Oncology & Biotech News what practicing oncologists should consider regarding his retrospective study, Dr Shaughnessy noted that “new drugs are expensive, but when you look at the cost, you need to look at the whole situation.” He commented that while chemo mobolization and plerixafor mobolization are both able to mobilize the stem cells, chemo mobolization can be more difficult on patients because it can lead to low blood counts, an increased need for transfusions, and a greater incidence of hospitalizations. Another benefit of a plerixafor regimen, according to Dr Shaughnessy, is that it makes treatment less complicated for healthcare staff because it ensures predictability of apheresis. He said, “If the cost is neutral, having less toxicity and more predictability and less will help both the patient and the clinical team.” ASH Abstract 2277.

Dr Shaughnessy received an honorarium from Genzyme, has served on its Board of Directors and advisory committees, and received Research Funding. The other investigators have served the same or similar functions or had consulting positions with Genzyme.

Disclosures: