Dept. of Internal Medicine, Division of Hematology and Oncology, University Hospital Charité, Campus Virchow-Klinikum, Humboldt-University, Berlin, Germany

Correspondence to: Dr G Massenkeil, Dept of Internal Medicine, Division of Hematology and Oncology, University Hospital Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany

Basiliximab, a chimeric interleukin-2 receptor (IL-2-R) antagonist, was evaluated in 17 patients with steroid-refractory acute graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (SCT). Patients were transplanted from a related (n = 6) or unrelated (n = 11) HLA-identical donor because of acute lymphoblastic leukemia (n = 4), acute myeloid leukemia (n = 3), chronic myeloid leukemia (n = 7), myelodysplastic syndrome (n = 1), non-Hodgkin's lymphoma (n = 1), and multiple myeloma (n = 1). Basiliximab was given at a dose of 2 ´ 20 mg on 2 consecutive days after steroid-refractory acute GVHD had developed. Basiliximab was repeated on day 8 in cases of persistent GVHD. A median of four basiliximab infusions (range 1-12) were given to these patients. None had infusion-associated or cytokine-related side-effects after basiliximab. Twelve of 17 patients (71%) responded to basiliximab, 9/17 (53%) had a complete response (CR) of acute GVHD and 3/17 (18%) had a partial response (PR). Five of 17 patients (29%) did not respond. Chronic GVHD developed in 8/13 evaluable patients and only 2/8 had responded to basiliximab before. Five of 13 evaluable patients have no signs of chronic GVHD and all five had a CR or PR after basiliximab. This is the first report on the safety of basiliximab in patients with steroid-refractory acute GVHD. Our data suggest that basiliximab is effective in a substantial proportion of these patients.

Bone Marrow Transplantation (2002) 30, 899-903. doi:10.1038/sj.bmt.1703737

allogeneic stem cell transplantation; acute graft-versus-host disease; steroid-refractory acute GVHD; interleukin-2 receptor antagonist; basiliximab

Acute graft-versus-host disease (GVHD) is the most important contributor to early transplant-related mortality (TRM) and also a strong predictor of chronic GVHD after allogeneic stem cell transplantation (SCT).¹ Prophylactic immunosuppression with cyclosporin A (CsA), methotrexate (MTX) and prednisolone does not always adequately prevent severe acute GVHD.^2,3,4 The prognosis of patients with acute GVHD refractory to high-dose prednisolone is poor and there is no established therapy for steroid-refractory GVHD.⁵

Basiliximab is a chimeric monoclonal antibody, which binds with high affinity to the alpha-chain of the interleukin-2 receptor (IL-2-R) and prevents the formation of the IL-2 binding site.⁶ Heterotrimerization and participation of the IL-2-R -chain in the IL-2-R complex confers high-affinity binding properties to IL-2 with subsequent rapid clonal expansion of activated T-lymphocytes.^7,8 Specific inhibition of T cell activation by IL-2-R -chain antibodies could interrupt the cascade of mutual cell activation, proliferation and cytokine release in the course of GVHD leading to tissue inflammation and destruction.⁹

Basiliximab has been evaluated and proven effective in phase III studies on the prophylaxis of acute rejection after renal transplantation. The frequency of immune responses to basiliximab was very low in these studies.^10,11

We have evaluated the safety and efficacy of basiliximab in the therapy of steroid-refractory GVHD after allogeneic SCT.

Patients and methods

Seventeen patients had undergone allogeneic SCT between December 1999 and August 2001 with mobilized peripheral stem cells and were treated with basiliximab because of steroid-refractory acute GVHD. Median age was 39 years (range 23-50 years). The majority of patients were suffering from acute leukemia or chronic myeloid leukemia (Table 1). Conditioning was with fractionated total body irradiation 2 Gy twice daily for 3 consecutive days (total 12 Gy) and high-dose chemotherapy with either cyclophosphamide 60 mg/kg once daily i.v. for 2 days (total 120 mg/kg) in 15/17 patients or etoposide 60 mg/kg once daily i.v. in one of 17 patients. One patient (No. 6) was retransplanted from a second donor due to graft failure after first SCT and received fludarabine 30 mg/m² once daily i.v. on 6 consecutive days (total 180 mg/m²), busulfan 4 mg/kg once daily p.o. on 2 days (total 8 mg/kg) and antithymocyte globulin 10 mg/kg by continuous i.v. infusion over 12 h for 4 consecutive days (total 40 mg/kg). All patients were transplanted from HLA-identical related or unrelated donors and serologic and molecular HLA-typing was performed in all of them for class I (locus A and B) and II (locus DRB₁ and DQB₁). GVHD prophylaxis was with CsA (2.5 mg/kg twice daily i.v.), MTX (15 mg/m², day 1, 10 mg/m², days 3, 6 and 11 i.v.) and prednisolone (0.5 mg/kg days 7-13, 1.0 mg/kg days 14-28, tapering afterwards) (Table 1).

After unrelated SCT, patients received G-CSF for faster hematopoietic reconstitution at a dose of 5 g/kg/day from day 5 until granulocytes were above 1.0 ´ 10⁹/l for 2 days.

Acute and chronic GVHD were classified according to Glucksberg¹² and Shulman.¹³ Clinical grading of GVHD before basiliximab and evaluation of response thereafter was performed daily in the morning before giving the immunosuppressive drugs, by two experienced hematologists. When acute GVHD was suspected, a skin biopsy was performed. In cases of suspected gut and liver GVHD, inconclusive skin biopsy or no skin involvement, gut biopsy or transjugular liver biopsy was performed.

Patients were eligible for basiliximab therapy if they had acute GVHD grade II to IV resistant to steroid therapy of 2 mg prednisolone/kg/day or more for 3 days at least. Basiliximab 20 mg was given intravenously over 20 min on 1 or 2 consecutive days and repeated weekly afterwards.

Improvement in GVHD was defined as complete response (CR), if patients had no clinical or biochemical signs of GVHD in all organs involved, ie no rash, normal bilirubin and no diarrhea. Partial response (PR) was defined as an improvement of one grade at least overall and no signs of deterioration in any of the organs involved.¹⁴ If GVHD recurred after initial response to basiliximab these patients were regarded as treatment failures. Patients were also followed for the later development of chronic GVHD.

Results

Acute GVHD became evident at a median of 25 days (8-68 days) after allogeneic SCT. Sites involved were skin (n = 5), skin and gut (n = 8), skin and liver (n = 1), gut and liver (n = 2), and skin, gut and liver (n = 1). Skin biopsies were performed in 14/15 patients with rashes, liver biopsies in two of four patients with an elevated bilirubin and gut biopsies in seven of 11 patients with diarrhea. All biopsies confirmed the clinical diagnosis of GvHD. Overall, 16/17 patients were biopsied and had histologic confirmation of GVHD; no biopsies were performed in 1/17 patients to confirm the clinical diagnosis (Table 2).

Fourteen of 17 patients had GVHD grade III or IV and three of 17 patients had GVHD grade II. Diagnosis of acute GVHD was followed by initiation of steroid therapy the same day. Two of 17 patients had received 2 mg/kg prednisolone i.v. and 15/17 had received 0.5-1.0 g methylprednisolone i.v./day. GVHD had not responded to steroid therapy in any of the patients. Time between the start of steroid therapy and first infusion of basiliximab was 7 days in median (range 3 to 25 days). All patients who had received prednisolone less than 5 days before basiliximab had had progressive GVHD, while on steroids alone (patients 2, 3, 4, 5, 13, see Table 3). Five of 17 patients had involvement of the skin alone, but in two of five, GVHD affected the whole body surface and pain was unbearable (grade III). Three of five had overall grade II, but skin GvHD had progressed while the patients were receiving steroid therapy.

A total of 66 basiliximab infusions were given to 17 patients, with a median of four (range 1-12) per patient (Figure 1).

At a median follow-up of 123 days after the first dose of basiliximab (15 to 502 days), an initial improvement in GVHD was seen in 15/17 patients. Three of them relapsed and became refractory to further therapy. Therefore, 5/17 patients (29%) were classified as nonresponders (Table 3).

Twelve of 17 patients (71%) had a significant response of acute GVHD to basiliximab. Latency between first basiliximab infusion and obvious response of GVHD of one grade at least was generally short, at a median of 2 days (1 to 8 days), usually after one to three doses (Table 3, Figure 2).

CR of acute GVHD was observed in 9/17 patients (53%). Three of 17 patients (18%) had a PR.

Chronic GVHD developed in eight of 13 evaluable patients (62%) and only two of eight patients had achieved CR of GVHD after basiliximab.

All five patients who did not develop chronic GVHD had CR of acute GvHD after basiliximab (Table 3).

Hematopoietic reconstitution was as expected in all patients; granulocytes >0.5/nl were reached after 15 days (range 10-19 days) and thrombocytes >20/nl after 17 days (range 11-26 days).

No bacterial or fungal infections were observed after basiliximab. Five of 17 patients developed CMV-reactivation, one with CMV-pneumonia. Two patients developed herpes labialis and herpes zoster, respectively.

At a median follow-up of 157 days after allogeneic SCT (range 31 to 513 days), nine of 17 patients (53%) are alive in complete remission of their primary disease. Eight patients have died. One of eight patients died from systemic inflammatory response syndrome 102 days after basiliximab; this patient was still receiving CsA and low-dose prednisolone and had no signs of GVHD at the time of death. Three of eight patients died from relapse of their primary disease 31 to 157 days after SCT; all three had been transplanted with advanced disease. Four of eight patients have succumbed to uncontrolled GVHD 65 to 157 days after SCT. Eight of 12 patients responding to basiliximab are alive, compared to one of five with refractory GVHD (Table 3).

Discussion

Prednisolone is the treatment of choice for acute GVHD.¹⁵ However, treatment of acute GVHD with steroids and other agents has limited efficacy and only 44% of patients respond to initial therapy. In those failing primary treatment, no standard therapy exists and TRM is high, emphasizing the need for more effective agents.⁵

To our knowledge, this is the first report on the safety and efficacy of basiliximab after allogeneic SCT. Only preliminary data have been reported on 12 patients with acute GVHD; 83% responded to basiliximab and 25% achieved a CR.¹⁶

Although the prognosis of acute GVHD grade II is more favorable than grade III-IV,¹⁷ we gave basiliximab to three of 17 patients with grade II, because GVHD had progressed, while on 1 g methylprednisolone for 3 days at least. In two other patients with skin disease alone of overall grade IIII, we decided to add basiliximab to the therapy, because the pain was unbearable. We have not observed any adverse side-effects related to infusion of basiliximab or cytokine release in these 17 patients. This is in line with the large phase III studies on the prophylaxis of organ rejection after renal transplantation.^10,11 The chimeric character of basiliximab seems to result in a very low rate of immunologic response. The rate of CMV-reactivation in our patients was within the expected range after allogeneic SCT.¹⁸ A causal relation between fatal systemic inflammatory response syndrome and basiliximab in one of our patients more than 3 months after use of the antibody seems to be very unlikely, because basiliximab blocks IL-2-R for only 30-45 days¹⁹ and the patient was still on low-dose prednisolone and cyclosporine A at that time. No further bacterial or fungal infections occurred in our patients, probably because all patients had reconstituted before receiving basiliximab.

The optimal dosing schedule of basiliximab is not known and its use in renal transplantation followed clinical criteria. 20 mg were injected on the day of renal transplantation and on day 4. The split was intended to avoid unnecessary use of basiliximab in cases of graft loss or severe infection early after transplantation.^10,11

Because of the steroid-refractory character of the acute GVHD, we decided to give 20 mg basiliximab on 2 consecutive days. 40 mg basiliximab are able to saturate CD25-positive lymphocytes for 26 ± 8 days.¹⁹ In those patients not reaching CR of acute GVHD within 1 week, basiliximab therapy was repeated because of the antibody's half-life of 6-7 days.¹⁹

Analysis of the efficacy of basiliximab is hampered by the small number of patients and the fact that combination immunosuppression was instituted in all patients before basiliximab. The interval between beginning prednisone therapy and basiliximab is short in some of the patients, but we decided to infuse basiliximab because of GVHD progression. However, a therapeutic effect of basiliximab is very likely because of the rapid and enduring improvement in acute GVHD in 71% and complete resolution of GVHD in 53% of the patients after basiliximab, who had not responded to high doses of prednisolone. Organ involvement did not predict response of GVHD to basiliximab, but the number of patients is too small to draw further conclusions.

A humanized IL-2-R antibody has been investigated by others. Overall responses of acute GVHD were seen in 40%, 51% and 66%, respectively, and complete responses were observed in 20%, 37% and 8%, respectively.^14,20,21 In contrast to our own observations, one of these studies reported an increased rate of infectious complications.²¹ No comparative studies between basiliximab and the humanized IL-2-R antagonist have been performed to date.

Compared to ATG therapy in steroid-resistant GVHD,²² side-effects of basiliximab are rare.

CsA, which inhibits IL-2 gene transcription through calcineurin inhibition,²³ and basiliximab, both interfere with T cell activation through different mechanisms and could therefore have additive effects on inhibition of T cell activation. Clinical data after renal transplantation have demonstrated an excess of graft rejection in patients treated with basiliximab, when CsA was absent.¹⁹ We have therefore decided to use basiliximab in steroid-refractory GVHD, only when CsA is part of the immunosuppressive regimen.

In conclusion, this first series of patients demonstrates that basiliximab can be safely given to patients with steroid-refractory acute GVHD. A substantial proportion of our patients responded to basiliximab, although basiliximab affects only one activation pathway of the immune system. We speculate, that basiliximab has to be started early in severe steroid-refractory acute GVHD to be of clinical benefit. Control of acute GVHD also seems to lower the rate of chronic GVHD in these patients. In view of the small number of patients reported, our data warrant further investigation of basiliximab in a larger number of patients to define its position in the treatment of steroid-refractory acute GVHD after allogeneic SCT.

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Figure 1 Time points of basiliximab infusions in 17 patients after allogeneic SCT. Each vertical line denote day of one basiliximab infusion after allogeneic SCT.

Figure 2 Acute gastrointestinal GVHD before and after basiliximab. Response of intestinal GVHD denoted by number of bowel movements per day to therapy with Predni = prednisolone; CsA = cyclosporin A; MP = methylprednisolone and basilimab in patient 11 with acute GVHD grade III.

Table 1 Patients' characteristics

Table 2 GVHD stage and grade before and after basiliximab

Table 3 Response to basiliximab and follow-up