Elevated Serum Hepcidin in Patients with AML Prior to and After Allogeneic Hematopoietic Cell Transplantation Does Not Correlate with Transfusional Body Iron, HFE Genotype or Graft Versus Host Disease and May Protect From Excessive Parenchymal Iron Loading.

42 consecutive pts (23 male/19 female, median age 57 [range:18-70] years) with AML who underwent allogeneic HCT from February, 2008 - February, 2009 at the University of Leipzig were included. Each patient was assessed 10 days prior to and at a median of 3 (range: 3-5) months after HCT. Donors were matched related in 8 (19%) and matched unrelated (MUD) in 34 (81%) pts. Preparative regimen consisted of 12 Gy TBI/cyclophosphamid 120 mg/kg (ATG was included for unrelated HCT) in 13 (31%) and fludarabin 30 mg/m²/day for 3 days/2 Gy TBI) in 29 (69%) pts. Acute GvHD > grade II was present in 13 (31%) and chronic GvHD in 17 (40%) pts. HFE genotype prior to and after HCT was assessed by PCR technique. Body iron was assessed by serum ferritin (sf) (normal values < 400ng/mL). Serum hep was measured by hepcidin C-ELISA at Intrinsic LifeSciences LLC, La Jolla, CA.(normal values: male 29-254 ng/mL, female: 17-286 ng/mL). Hep levels of 21 age-and gender-matched healthy volunteers (6 m/15 f, median age 57 years) were used as a control.

Median serum hep was much higher in pts both prior to [median 358 (range:56-1096) ng/ml] and after HCT [median 398 (range:172-941) ng/ml] compared with the control group [median 52 (range:8.3-131) ng/ml] (p<0.0001). Age and gender had no influence on hep values. Similarly, liver function, interval between diagnosis and HCT, number of chemotherapies, conditioning regimen, antibiotic- or antifungal-treatments had no impact on hep level. Iron overload was already seen in all pts prior to HCT with a median sf of 1945 (range: 617-6981) ng/mL after a median number of 22 units BT. Although after HCT the number of BT mounted to a median of 30 units (p<0.0001), sf with a median of 2260 ng/mL remained elevated comparable to the level prior to HCT. Lower hep levels significantly correlated with fewer BT (p=0.001), but surprisingly not with sf values. Hep correlated inversely with the degree of anemia (p=0.002). Mutations in the HFE gene were found in 19 (46%) pts prior to HCT (heterozygosity (het) for H63D, n=11, het C282Y, n=3, het S65C, n=1, and homozygosity (homo) for H63D, n=4) and in 15 (37.5%) pts after HCT reflecting donor genotype (het for H63D,n=12, het C282Y, n=1, compound-het, n=1). Mutations in the HFE gene were not associated with lower hep levels.

After HCT, 19 (45%) pts showed a decline in hep level of 155 (range: 394.8-9.5) ng/ml and 23 (55%) pts had an increase in hep levels of 138 (range: 43.3- 620.9) ng/ml compared with pre-transplantaion levels. None of the above mentioned parameters could predict or correlate with these changes in serum hep. Iron overload prior to HCT strongly correlated with later extensive chronic GvHD (p=0.003) and tended to correlate with limited GvHD (p=0.06). On the other hand, hep levels at any time point did not correlate with acute or later chronic GvHD.

Serum hepcidin is highly elevated in pts with AML prior to as well as after allogeneic HCT compared with healthy controls mainly because of frequent blood transfusions leading to elevated iron stores. This suggests that hepcidin synthesis and upregulation remain intact despite intensive chemotherapy and HCT. Hepcidin normally binds to ferroportin, leading to intracellular retention of iron in macrophages and to a reduction of extracellular serum iron. This may explain why serum hepcidin correlates with blood transfusions but not with serum ferritin values. Actually, overexpression of hepcidin may play an important protective role in this setting as it may prevent an increased ferroportin-mediated iron export from macrophages thereby reducing the severity of parenchymal iron loading and damage.

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