Efficacy of plerixafor in children with malignant tumors failing to mobilize a sufficient number of hematopoietic progenitors with G-CSF

Abstract

Mobilization of suitable amounts of PBSCs with granulocyte-CSF (G-CSF) can be difficult in children. We report the results of using plerixafor in pediatric patients who failed to mobilize progenitors with G-CSF-based regimens. Thirty-three patients, median age 9 years (range 1-18 years) and median weight 29 kg (range 10-85 kg) were enrolled into the study. After 4 days of G-CSF stimulation, the median CD34+ cell count in peripheral blood was 10.4 per μL (range 0.27-23.0 per μL). Plerixafor was administered subcutaneously (0.24 μg/kg in 30 patients and 0.3 μg/kg in 3 patients) 11-12 h before apheresis. At the time of apheresis, CD34+ cell counts increased to a median of 44.1 per μL (range 8.4-357.0 per μL), a median 4.4-fold increase. Two patients (6%) failed to mobilize. Thirty-one patients underwent apheresis and in 27 42 × 10 6 CD34+ cells per kg of body weight were collected after one procedure. In total, 31 of 33 patients mobilized successfully and the median number of cryopreserved CD34+ cells was 5.6 × 10 6 /kg body weight (2.7 × 10 6 -27.4 × 10 6 ). Twenty-four patients underwent transplantation. Engraftment was achieved in all but one patient, who died on day +9 after hematopoietic stem cell transplantation. The median time of neutrophil and platelet recovery was day +12 and +16, respectively. Our study confirms that plerixafor has impressive efficacy and very modest toxicity in children.

Peripheric Stem Cell Collection Practices At Childhood

“…Otolog nakillerde hastanın altta yatan kanser hastalığına uygun kemoterapi rejimi verildikten sonra G-CSF tedavisine başlanır (10 µg/kg/gün) ve beyaz küre sayısının dip seviyeye düşmesi beklenir, bu süre kullanılan kemoterapiye bağlı olup, genellikle 7-8 gündür (4,5) . Sonrasında beyaz küre sayısı günlük takip edilir, genellikle beyaz küre sayısı 1000/µL ve CD34 pozitif hücre sayısı >10/µL ise HPKH toplanabilir (1,4) .…”

“…CD34 pozitif hücre sayısı için genel kabul görür bir eşik değer yoktur. Bazı merkezler 20/µL'ye kadar yüksel-mesini önerir ama periferik kanda HPKH'nin yük-sekliği birkaç gün gibi kısa bir süre olduğu için bu dönem kaçırılmamalıdır (1,5,6) .…”

“…Erişkin çalışmalarında etkinliği gösterilmiş plerixafor, HPKH'lerin yüzeyinde bulunup kemik iliği stromasına tutunmalarını sağlayan CXCR4 reseptörüne bağlanarak HPKH mobilizasyonunu sağlar (7) . Çocuk serilerinde de G-CSF ile yeterli mobilizasyon sağla-namayan hastalarda etkinliği ve güvenliği gösteril-miştir (5) . Plerixafor, G-CSF ile kombine olarak, subkutan olarak 0.24 mg/kg dozunda uygulanmakta, etkin mobilizasyonun 6-12 saat sonra olmaktadır.…”

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“…3 This has not been confirmed by others. 2,4 Both our children received just 1 dose of plerixafor, and we did not observe any significant adverse effects. It is possible that multiple doses may lead to these kinds of above-mentioned adverse effects.…”

“…One large pediatric study has documented safety of plerixafor in children. 4 In India, a generic version Mozifor is licensed for use, which costs about USD $1230. A second recovery with conventional methods at our center will cost approximately USD $750 (which may not collect sufficient stem cells).…”