Inflammatory bowel diseases (IBD) in 15% to 25% of cases begin in childhood (1). Given that the prevalence of IBD in children is rising, it represents an important field of interest in pediatric gastroenterology (2). The aim of therapy in children with IBD is not only to induce remission of disease and to prevent relapse but also to guarantee normal growth and pubertal development (3,4). Disregulation of the immune system plays an important role in the development of chronic bowel inflammation, where conventional therapy is represented by 5-aminosalicylate (5-ASA), corticosteroids, and immunosuppressive agents. Steroids, azathioprine, and 6-mercaptopurine are widely used, but despite their efficacy, serious and sometimes irreversible side effects are reported. Steroid dependency (20%–36%) and resistance (20%) can occur, facilitating reduction of bone mineral density (5,6); intolerance to or toxicity from immunosuppressive agents occurs in 10% to 15% of patients (7,8). Infliximab has offered an important alternative in the treatment of patients with Crohn disease (CD), but serious adverse events and severe opportunistic infections, tuberculosis reactivation, and malignancies, even if not frequently reported, may limit its use, especially in childhood (2,3,9–11).
Recent studies report that when autologous red blood cells (RBCs) are used as drug carriers (12), low doses of dexamethasone 21-P (Dex 21-P) can be delivered in the blood circulation with therapeutic efficacy and without side effects in cystic fibrosis (13). The same technique has been used in children with CD (14) and recently in adults with CD and ulcerative colitis (15), confirming its safety and efficacy. The aim of this pilot uncontrolled study was to assess whether long-term treatment with repeated infusions of RBCs loaded with Dex 21-P can cause side effects and allow maintenance of long-term remission in children with steroid-dependent CD.
PATIENTS AND METHODS
Eighteen consecutive pediatric patients with moderately active CD were admitted to the study (Table 1). All of them initially responded to corticosteroids but experienced relapse with corticosteroid tapering or shortly after discontinuation of corticosteroids; they required reinstitution of the therapy at dosages exceeding 10 mg/day to maintain symptom control and were considered steroid dependent. The diagnosis of CD was made on the basis of the clinical history; physical examination results; and radiological, endoscopic, and histological findings (5,16–18). All of the patients received treatment with conventional therapy (5-ASA, steroids, and azathioprine). Before entering the study, 4 patients required treatment with infliximab, which was interrupted because of serious side effects at least 3 months before infusions were started. At the beginning of treatment, all of the patients were receiving 5-ASA and azathioprine at conventional dosages and steroids at the minimal effective dose. The steroid daily dose in milligrams was calculated as follows: the total amount of oral steroids received in the past year before RBC infusions were started, divided by 365 days; none of the patients received steroids for 365 days consecutively.
Before and after each infusion, all of the patients underwent biochemical and clinical evaluation according to the Pediatric Crohn Disease Activity Index (pCDAI) (19). Twelve months after the beginning of treatment, endoscopic and histological evaluation were also performed. During treatment with loaded RBCs, steroid therapy was tapered and discontinued when possible. The pretreatment and posttreatment amounts of steroids were evaluated for each patient as a mean daily dose, whereas other therapies were not modified. Bone mineral density (BMD) by means of computerized bone density mineralometry-dual energy x-ray absorptiometry (CBM-DEXA) and body mass index were assessed before the start of treatment and during treatment. Blood pressure and heart rate were evaluated during each session. In all of the patients we performed a determination of hematic morning cortisol before infusion and at 1, 3, 14, and 28 days afterward. Informed consent was obtained from all patients' parents. The study protocol was approved by the ethical committee of our hospital.
After complete evaluation, all of the selected patients were treated at 4-week intervals with infusions of autologous RBCs loaded with Dex 21-P. The preparation of engineered RBCs has been described elsewhere (12,13,15). Each session lasted approximately 2 hours at room temperature and under blood-banking conditions. Briefly, approximately 50 mL of blood was collected from each patient in a heparinized syringe, mixed with normal saline, and then centrifuged to obtain RBCs that were mixed to hypotonic solutions to allow opening of membrane pores. Subsequently, lysed RBCs were concentrated in a hemofilter, and Dex 21-P (0.5 mg) was added. After a new equilibrium was reached, restoration of osmolarity allowed the RBCs to close the membrane pores. Nontrapped drug was washed out, and the loaded RBCs were ready to be reinfused into the original donor in 30 minutes. The amount of Dex 21-P administered by RBCs was evaluated by high-performance liquid chromatography as previously described (12). Once reinfused into patients, the nondiffusible pro-drug Dex 21-P was slowly dephosphorylated by erythrocyte-resident enzymes to the diffusible dexamethasone, allowing a small and constant dose of corticosteroid to be introduced into the blood circulation. In our previous study (13) the pharmacokinetics of dexamethasone after a single administration of drug-loaded cells showed an initial increment of hematic steroid, followed by a stabilization of the levels after 48 hours. This level remained stable for 28 days (13), as was also confirmed by a recent study in adults (15). For this reason, infusions were performed at 4-week intervals. The results were expressed as mean and standard deviation or range; statistical evaluation was performed by use of the Wilcoxon matched-pair test. P < 0.05 were considered statistically significant.
Eighteen patients (10 female, 8 male), mean age 13.7 years (range 5.4–18 years) at the beginning of the treatment with RBCs loaded with Dex 21-P, were studied. The mean interval from diagnosis to the beginning of treatment was 32 months (range 5–129 months). The results refer to patients during the follow-up, and data were collected at 6-, 12-, and 24-month intervals from the beginning of therapy. Only 2 patients dropped out after 24 months of therapy because they could not guarantee further compliance with the therapeutic program.
The mean amount of Dex 21-P administered by RBCs was 8.8 milligrams (range 2.4–14.7 mg) for each infusion. At the beginning, the mean pCDAI was 23.8 ± 20.03, with a decrement to 15 ± 11.8 at 6 months (P not significant), 14 ± 10.13 at 12 months (P not significant), and 9.6 ± 7.47 at 24 months of treatment (P < 0.05) (Fig. 1); oral dosage of steroids before treatment was 11.1 ± 10.06 mg/day, the minimal efficacious dosage to maintain remission. Steroids were completely discontinued in 14 patients (78%). In the 4 children who could not discontinue oral steroids, the mean daily dosage decreased from 21.87 ± 7.8 mg/day to 15.43 ± 4.46 mg/day. The mean hospitalization rate for patients before treatment was 30.15 days/year; it fell to 13.9 days/year during treatment (P < 0.02). The mean body mass index was 20.5 at the beginning and did not significantly change during therapy (P not significant).
CBM-DEXA was evaluated after a mean period of 20.8 months (range 6–30 months). The BMD showed an improvement in 6 patients (33%) and no variation in others. Endoscopic and histologic evaluation were done 12 months after the start of treatment and showed remission in 8 patients (44%) and some improvement in 10 (56%).
Determination of hematic cortisol showed suppression of endogenous morning cortisol the first day after infusion, followed by fast normalization of values within 3 days after infusion; the values remained within the normal range until the next infusion (Fig. 2). In all of the patients, the blood pressure and heart rate did not significantly change during each session. None of the patients showed any serious side effects. A sense of well-being was experienced by all children during treatment.
The aim of IBD treatment in childhood is to avoid recurrence of disease and to guarantee normal growth and pubertal development. Corticosteroids are effective, but unfortunately bone demineralization and growth retardation are a particular drawback to repeated administrations. At least 15% of children with IBD experience a reduction in BMD, and systemic steroids are not recommended for long-term treatment (20,21). Immunosuppressive agents and infliximab are widely used also in pediatric CD, but serious adverse events that lead to the discontinuation of therapy have been reported (2,9–11). Recent efforts have been made to find new effective therapeutic strategies with limited side effects, especially in children, who are usually affected by more aggressive and long-lasting disease (3).
We previously reported the lack of side effects and the effectiveness of treatment with RBCs loaded with Dex 21-P in patients with cystic fibrosis (13). These data suggested that this technique could also be used in children with steroid-dependent, mild to moderate CD who are difficult to treat and who do not receive any benefit from steroid-sparing drugs.
In patients with CD treated with periodic infusions of autologous erythrocytes loaded with Dex 21-P, we noticed a progressive reduction of pCDAI in the first 6 months of treatment, but a decrement reached statistical significance within 24 months. Our studies showed that 78% of our patients were able to interrupt oral steroid treatment, and the remaining patients could reduce the dosage, thus limiting the side effects of such therapy. The lack of serious adverse effects was confirmed by the results of the CBM-DEXA examinations, which showed improvement (33% of patients) or no variation (67% of patients) in BMD after a mean of 20.8 months (range 6–30 months) from the first infusion. Determination of hematic cortisol confirmed and justified the lack of interference with the adrenocortical axis. Part of the safety of this therapy seems to be due to the short-term inhibition of the adrenocorticoid axis, given that hematic morning cortisol in our patients rose to the normal range after 3 days from infusion.
The therapeutic action could be due to the slow daily release of dexamethasone from RBCs that guarantees a small but constant amount of steroids in the blood circulation. The rate of steroids entrapped on RBCs (∼9 mg/infusion) is low enough to avoid serious side effects but seems to be sufficient to guarantee the minimum effective dose required to maintain remission of disease.
The most important features of this treatment are the efficacy and absence of side effects, which encourage its use in the treatment of mild to moderate steroid-dependent CD in pediatric patients. Also significant are the data on the reduced hospitalization rate and the improvement in the sense of well-being and lack of interference with daily activity experienced by our patients. The reduced hospitalization rate and the lack of serious adverse effects also contribute to the reduction of the costs involved in treating the disease.
Despite the sense of well-being and the reduction of pCDAI, 10 patients did not show any improvement in the histological findings, but the lack of correspondence between the endoscopic/histological findings and the clinical picture is not surprising. These data have already been reported in previous studies describing the lack of correspondence between a sense of well-being, a fall in the inflammatory index, and improvement of histological features in patients treated with systemic steroids (22).
In conclusion, periodic infusions of autologous RBCs loaded with Dex 21-P can represent a new safe and effective approach to obtain and maintain long-term remission in pediatric patients with steroid-dependent mild to moderate active CD. This treatment could offer an alternative for patients not responding to conventional therapy, who present serious side effects, or who are not eligible for biological therapies. Further controlled studies should be performed to assess both the efficacy and the safety of this therapy in patients with IBD, especially children and adolescents, whose linear growth may be seriously compromised by the use of high doses of steroids.
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