1 Fifth Medical Clinic, University Hospital Mannheim, Heidelberg University, Mannheim, 2 Euro Nippon Kayaku GmbH, Frankfurt, 3 Department of Nephrology, University Hospital Berlin-Buch, Berlin and 4 Division of Rheumatology and Clinical Immunology, Department of Medicine, Freiburg University Hospital, Freiburg, Germany
Correspondence and offprint requests to: Dr Wilhelm H. Schmitt, MD, Fifth Medical Clinic (Nephrology/Endocrinology/Rheumatology), University Hospital Mannheim, Theodor-Kutzer-Ufer 13, D-68135 Mannheim, Germany. Email: wilhelm.schmitt{at}med5.ma.uni-heidelberg.de
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Abstract |
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Methods. To document the effects of prolonged DSG treatment, this study reports on seven patients suffering refractory Wegener's granulomatosis, who were successfully treated with DSG over an average of 26.5 months (range: 1155.5 months).
Results. Before administration of DSG, patients had experienced an average of 6.6 relapses (range: 312) under an average of 5.4 (range: 211) different therapeutic approaches, which included CYC in all cases. All suffered active disease when DSG was initiated. Four were unresponsive to CYC and three did not tolerate it. DSG (0.5 mg/kg/day subcutaneous) was given for 23 weeks until the leukocyte count dropped to 3000/µl, followed by a rest until a leukocyte count of 4000/µl was reached again. No other immunosuppressants besides corticosteroids were given. All patients showed a long-lasting, favourable response to DSG with complete (n = 5) or partial (n = 2) remission. Only one case relapsed while being treated with DSG. Termination/interruption of DSG was followed by relapse in four of five occasions. Resumption of DSG led to complete remission. Currently, five of the seven patients are still treated with DSG and are in remission. Infections, mainly of the respiratory tract, were observed in five cases and resolved after treatment. One case developed a third-degree heart block that required pacing.
Conclusions. In patients with refractory Wegener's granulomatosis, prolonged treatment with DSG seems safe and successful.
Keywords: 15-deoxyspergualin; immunosuppression; vasculitis; Wegener's granulomatosis
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Introduction |
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15-Deoxyspergualin (DSG; generic name: gusperimus) is a synthetic analogue of spergualin, a natural product of the bacterium Bacillus laterosporus. Spergualin was discovered in 1981 by Takeuchi et al. [2] in a culture filtrate while screening for natural products that inhibit the transformation of chicken embryo fibroblasts through Rous sarcoma virus. Subsequently, in various animal models of transplantation and autoimmune diseases, such as experimental crescentic glomerulonephritis and lupus nephritis [3], the drug was shown to possess strong immunosuppressive properties. The precise mechanisms of action are not understood clearly, but from the available data it seems that DSG inhibits both T- and B-cell differentiation, possibly by blocking the nuclear translocation of transcription factor NF-B [46]. In clinical trials of recurrent kidney transplant rejections, DSG, which was generally given at 3 or 5 mg/kg/day by 3 h intravenous (IV) infusion for 57 days, led to remission in 79% of cases and was shown to be of similar efficacy as the monoclonal antibody OKT3 [7]. Later, Hotta et al. [8] demonstrated a therapeutic potential of DSG in four patients with crescentic proliferative glomerulonephritis using a low-dose regimen of DSG, which was administered at daily doses of 0.25 and 0.5 mg/kg by 1 h IV infusion for 28 days. From pre-clinical and clinical data it appears that DSG is a potent immunosuppressant with a favourable side-effect profile, exerting no renal and liver toxicity and only reversible bone marrow suppression [79]. Based on these favourable results, we previously conducted an open-label pilot trial of DSG in 20 patients with active WG or microscopic polyangiitis refractory to standard immunosuppressants [10]. Fourteen of 19 cases of WG showed a favourable response to DSG, with six complete and eight partial remissions. Four cases continued treatment with DSG after termination of the trial on a compassionate use basis. We now report the further course of these patients and of three further cases that subsequently were treated with DSG for refractory WG.
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Subjects and methods |
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Disease extent
The extent of disease was assessed at entry and subsequently every 4 weeks or at relapse using the disease extent index (DEI) as described previously [12]. Organ manifestations were recorded as follows: E, upper respiratory tract; L, lung; K, kidney; Ey, eye; H, cardiac involvement; S, skin; C, central nervous system; P, peripheral nervous system; A, arthritis/arthralgias and myalgias; GI, gastrointestinal manifestation (each organ: two points); B, constitutional symptoms (fever >38°C, undesired weight loss >10% of body weight within <6 months) (one point). The maximum possible score was 21 points.
Disease activity
Disease activity was assessed at the same time-points as disease extent using the Birmingham Vasculitis Activity Score (BVAS) [13]. The BVAS is calculated from new or deteriorated symptoms and signs within the previous month attributable to active vasculitis in nine separate organ systems that are weighed according to their relative contribution to mortality and morbidity of systemic vasculitis. The maximum possible score was 63.
Definition of remission
The activity of disease was evaluated according to clinical, radiological and serological data. Adopted from the criteria used within the therapeutic trials of EUVAS, complete remission was defined as the absence of pathological findings in these variables attributable to active vasculitis, irrespective of ANCA titres. The absence of clinical disease activity was indicated by a BVAS and DEI of zero. Partial remission was defined as partial regression of disease activity. Response to DSG therapy was defined as induction of partial or complete remission for 1 month [11,14].
Definition of relapse
As described previously [11], major relapse required the recurrence of active disease threatening the function of major organs (e.g. glomerulonephritis, pulmonary infiltrates or granulomata). Minor relapse required the recurrence of less-severe disease (i) in non-vital organs (e.g. arthralgia and nasal crusting) or (ii) involving vital organs without threatening organ function (e.g. pulmonary symptoms, such as cough or wheeze without radiological changes).
Treatment protocol
It was the hypothesis of the study that DSG is able to induce and then to maintain remission of refractory WG. Inclusion criteria were biopsy-proven WG with a refractory course as defined by the criteria given above. Exclusion criteria were a leukocyte count <4000/µl, pregnancy and lactation, the presence of uncontrolled acute or chronic infections, anticonvulsive treatment and inadequate contraception. Endpoints were induction of remission as the primary endpoint and maintenance of remission, sparing of immunosuppressants and side effects of DSG as secondary endpoints.
Administration of DSG
Cytotoxic agents, IV immunoglobulins or plasma exchange had to be discontinued before and were not given during DSG treatment. Corticosteroids were allowed according to local practice. As described previously [10], all patients were given cycles of DSG in a dosage of 0.5 mg/kg daily by self administered subcutaneous (SC) injection. Patients 1 and 2 received the first week of DSG treatment by IV injection with the same dosage. Within each cycle, DSG was given for 23 weeks with the aim to reach a leukocyte (WBC) nadir of 3000/µl. WBC were monitored at least twice weekly. At the nadir, treatment was discontinued for 2 weeks to allow the leukocyte count to recover (WBC
4000/µl). Then, treatment was resumed in the same way.
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Results |
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At the time of DSG administration, the patients showed a mean DEI of 5.1 (range: 39), indicating generalized active disease. Major organ involvement, threatening organ function, was present in all but one patient (Table 2). Four patients had severe pulmonary or subglottic disease (two suspected pulmonary granulomata and two subglottic stenosis, plus pulmonary infiltrates in one) and three suffered renal involvement. Immediately prior to DSG treatment, all patients were taking immunosuppressive drugs, including GC (mean dosage: 18.3 mg/day; range: 575 mg/day), that failed to control disease activity (Table 2).
Treatment effects
All patients showed a favourable response with complete (n = 5) or partial (n = 2) remission of disease activity (Table 3). Beneficial effects were observed both in lesions of (suspected) granulomatous nature, such as pulmonary opacities and subglottic stenosis, and in lesions thought to be of merely vasculitic origin, such as pulmonary infiltrates, episcleritis and polyneuropathy. Noteworthy, this did include complete resolution of severe disease activity in two of three cases of subglottic stenoses, two cases of pulmonary nodules/infiltrates (one case each) and two cases of glomerulonephritis.
Under the administration of DSG, the disease extent declined, as indicated by a drop of the DEI from 5.1 prior to DSG to 0.4 (range: 02) after 6 months and to 0.6 (range: 03) at the latest follow-up under DSG. Accordingly, a reduction of disease activity was demonstrated by a fall of the BVAS score from 16.1 (range: 425) directly before the start of DSG to 2.0 (range: 07) after 6 months and 1.2 (range: 09) at the latest follow-up under the study drug (individual data given in Table 3). Remaining disease activity in the two patients with partial remission was restricted to residual lesions of subglottic stenosis and nasal crusting (one case each). The full effect of DSG became apparent no earlier than after 8 weeks of treatment (not before the end of cycle 2), on average after 3 months, following 2.9 cycles of DSG. Two cases (patients 1 and 2 during their first course of DSG) achieved complete remission only after four cycles.
Although the use of GC could be stopped in only two cases, the average dose of prednisolone could be reduced from 18.3 mg/day (range: 575 mg/day) directly prior to DSG to 4.3 mg/day (range: 07.5 mg/day) at the latest follow-up under the study drug.
Because the clinical course of most patients was stabilized under DSG, the drug was continued for a long time, on average for 26.5 months (range: 1155.5 months). Only one of the seven patients (case 4), who had only achieved partial remission, relapsed on the drug and developed pulmonary nodules, haemoptysis and constitutional symptoms after treatment with DSG over 11 months. This major relapse responded to CYC boli and GC boli. In three of the remaining cases, who all went into complete remission, DSG was stopped after 16, 27 and 27 months, respectively. All received maintenance therapy with GC and/or other drugs, as specified in Table 3. Two of them (patients 1 and 2) subsequently relapsed after 1 and 2 months (one major and one minor relapse). During their further course, both of them received additional immunosuppressive treatments, including etanercept [tumour necrosis factor (TNF)- blocker] and mycophenolate mofetil (plus antithymocyte globulin in patient 2), but no CYC, as they did not tolerate it, without long-lasting effect. Finally, treatment with DSG was resumed in both and resulted in complete remission (follow-up time: 49 and 20 months; Tables 2 and 3). In two cases, treatment was interrupted on three occasions for 2 months because of infection (patient 1, second course) or for logistical reasons (patient 3, two episodes). All these episodes were followed by a relapse that resolved after resumption of DSG (Table 3). Patients who had received CYC directly before DSG was initiated seemed to respond equally well as those who were on other agents.
Dosage of DSG other than 0.5 mg/kg
Eleven months (range: 912 months) after induction of complete remission using 0.5 mg/kg DSG, the dose of DSG was decreased to 0.3 mg/kg in two cases (patients 1 and 2, first course of DSG) and 0.2 mg/kg in one case (patient 3, details given in Table 3) in order to avoid infections. In patients 1 and 3, the duration of cycles was furthermore fixed at 2 weeks and leukopenia did not develop. The patients were kept on this regimen for 43.5, 45 and 14 months, with complete control of the disease.
ANCA
ANCA were positive in all patients directly before DSG treatment, as detected by indirect immunofluorescence and/or proteinase-3 enzyme-linked immunosorbent assay. Follow-up on ANCA titres was available in six cases. Under DSG, ANCA titres became negative in three, declined by more than two titre-steps in one and remained unchanged in two cases.
Leukopenia
Within each treatment cycle, the targeted level of leukopenia (WBC nadir of 3000/µl) was induced in all patients, after an average of 3 weeks of treatment. The duration of treatment cycles did not change significantly during the observation period. In all cases leukopenia was transient and followed a foreseeable course without any signs of increased toxicity associated with the long-term use of DSG. As described previously [10], DSG affected mainly neutrophil counts. During the treatment period, the intervals between WBC determinations were therefore extended from checks performed initially every other day [10] to a regimen where WBC determinations were started not before the second week during each cycle and were limited to two determinations per week. In contrast to neutrophil counts, lymphocyte and monocyte counts were hardly affected by DSG treatment. A slight decrease in absolute lymphocyte counts of 20% below the normal range was observed in four of the seven patients (Table 4). In three of them, lymphopenia was associated with neutropenia. A relation between lymphopenia and remission could not be detected, as the non-lymphopenic cases equally responded to DSG.
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Besides the above-mentioned side effects, local and systemic tolerability of DSG was excellent. Only one patient experienced a painful exanthema following each injection, which resolved always after 12 h. Treatment with DSG was not interrupted.
Slight decreases in haemoglobin levels and thrombocytes were noted in two of the seven cases, but were clinically insignificant with the exception of patient 2, who additionally suffered from concomitant renal insufficiency due to renal scarring. During her second course of DSG, anaemia aggravated under DSG in conjunction with worsening renal function (active glomerulonephritis excluded by biopsy) and required the use of erythropoietin.
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Discussion |
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One might argue that concomitant treatment with GC added significantly to the favourable response of DSG. However, it is known that treatment with GC alone is not capable of inducing or maintaining remission in WG [1]. Also, all patients had received GC before the administration of DSG, without control of disease activity. Finally, the dose of GC could be reduced from an average of 18.3 mg/day (range: 575 mg/day) directly prior to DSG to 4.3 mg/day (range: 07.5 mg/day) at the latest follow-up under the drug and two cases were able to completely stop GC treatment.
It cannot be excluded fully that a postponed effect of the other immunosuppressants given prior to study entry contributed to the favourable course of the patients under DSG. However, it seems unlikely that the effect of these drugs continued for several months or years under sole treatment with the study drug. Furthermore, the patients were selected for DSG treatment on the assumption that the previous immunosuppressive medications were either not sufficiently effective or were contraindicated due to severe side effects. In fact, four of the seven patients showed progressive disease under the standard therapy with CYC and GC and clearly improved following the employment of DSG. However, it should be stressed that as in other immunosuppressive drugs the full effect of DSG treatment became apparent not earlier than after 8 weeks of treatment, on average after 3 months, following 2.9 cycles of DSG.
It is noteworthy that preliminary experience with anisperimus (LF 15-0195), a derivative of DSG, showed a similar response rate in patients with refractory systemic vasculitis, mostly ANCA-associated vasculitis (induction of remission in seven out of nine cases), thereby confirming this novel therapeutic approach [15].
A selection bias may have contributed to the favourable results reported here, as only those four patients of the pilot trial were included in the long-term study who were kept on DSG treatment because they had shown a beneficial response. It should be mentioned, however, that only three of the 19 WG cases reported in the initial pilot trial relapsed during treatment with DSG and only one patient had not responded at all. In two further patients, DSG had to be stopped due to side effects. In contrast, the majority of cases (13/19) did successfully complete the pilot trial and could have been kept on DSG further. For unclear reasons, however, only four of these 13 were selected for continuous treatment with DSG by their local physicians and are reported here. The other nine patients were switched to different regimens of maintenance therapy. Two of them relapsed during the following 6 months [10].
The present study extends the previous observation that treatment with DSG, given in a cycled manner at daily dosages of 0.5 mg/kg SC until the target leukocyte count of 3000 cells/µl is reached, was feasible and safe [10]. This regimen is in contrast to the treatment schemes applied in acute kidney rejection, where DSG is normally used in doses ranging from 3 to 5 mg/kg/day for 57 days [7,9]. However, data from animal models and the initial clinical experience from patients with various forms of proliferative glomerulonephritides with or without crescent formation [8] suggest that the efficacy of DSG may be dependent on the duration of application rather than on the absolute amount given. This impression is now further substantiated by the experience in three patients who were treated with even smaller doses of 0.3 (two cases) and 0.2 mg/kg, without a loss of efficacy. In two of these patients, the duration of treatment cycles was restricted to 2 weeks, independent of whether the leukocyte nadir of 3000 cells/µl was reached or not. In fact, both of these patients retained normal leukocyte counts during their treatment cycles, without any apparent loss of efficacy. Monitoring of treatment was, therefore, much easier in these cases. However, the number of patients needs to be extended before definite conclusions can be drawn.
Despite the prolonged administration of DSG reported here, long-term tolerability was good and no increase in the incidence of side effects over time could be observed. Importantly, the duration of treatment cycles was stable over time, with an average of 3 weeks per cycle, until the target leukocyte count 3000 cells/µl was reached. Thus, no signs of cumulative bone marrow toxicity of the drug after repeated cycles were observed.
Despite the significant reduction in neutrophil counts induced by a dosage of 0.5 mg/kg DSG within each cycle, most infections observed under the study drug were of mild to moderate intensity and resolved after adequate treatment. The rate of infections was in the range that could be expected from previous trials in ANCA-associated vasculitis. A good tolerability of DSG was also observed in other studies, including phase I studies that involved patients suffering from renal allograft rejection, crescentic glomerulonephritis and various advanced cancers. These treatment regimens included short-term doses of 75 mg/kg/day, given mostly as 3 h infusions for
7 days. The main adverse effects, listed in Table 5, were transient and included leukopenia, anaemia and thrombocytopenia, hypotension, oral numbness and infections, which were mostly mild with the exception of one case of septicaemia. A randomized, double-blind study of DSG in multiple sclerosis, which employed placebo or 2 or 6 mg/kg DSG given IV in five 4 day courses at 4-week intervals did not demonstrate any differences in the number and severity of adverse effects during a 2 year follow-up period, beside a mild and transient leukopenia and anaemia that was noted in association with the treatment phases. No long-term toxicities were reported [3]. Furthermore, in all clinical and pre-clinical studies, DSG revealed no mutagenicity, teratogenicity or carcinogenicity [3].
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DSG clearly affects both T- and B-cell differentiation, but the precise mechanism of action remains obscure. It inhibits the growth of naïve CD4 T cells after activation and the production of interferon- by Th1 effector cells [4]. It also leads to an arrest of T-lymphocyte maturation in the thymus during CD4CD8 to CD4+CD8+ transition [6]. B-cell maturation and
light-chain expression is reduced as well, possibly by blocking the nuclear translocation of transcription factor NF-
B [5]. Finally, also the antigen presentation by macrophages was shown to be altered under DSG, including a diminished expression of MHC class II antigens in conjunction with a reduced production of TNF-
and interleukin-1ß [16].
Finally, the availability of alternative experimental therapies for patients with refractory WG needs to be mentioned. Although most of the work has been published only in abstract form, B-cell depletion by a monoclonal anti-CD 20 antibody (rituximab) was successfully used, with few side effects [17], and may be a therapeutic option especially in patients who developed infections under conventional therapeutic agents. Furthermore, anti-TNF- blockade [18] and anti-T cell-directed treatment [11] may be therapeutic options in patients who do not respond to conventional means.
In conclusion, prolonged treatment with DSG appeared effective and safe in seven patients with refractory WG who showed active, progressive disease despite standard treatment with GC and CYC or who did not tolerate CYC. Although the study was open and uncontrolled and the number of patients was small, the standardized regimen employed here seems promising for both the induction and the maintenance of remission in WG. Prolonged administration of the drug did not lead to increased toxicity and the main side effects were infections of mild to moderate intensity, all of which could be controlled with appropriate therapy. However, the treatment regimen employed here necessitates determination of blood cell counts in regular intervals to monitor the myelosuppressive effects of the drug. It remains an open question whether a treatment regimen with lower doses of the drug, which may avoid myelosuppression, would be equally effective. In view of the good tolerability of the drug, randomized studies are warranted to investigate the efficacy DSG in comparison with CYC as a secondary or even primary agent in patients with active WG.
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Acknowledgments |
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Conflict of interest statement. W.H.S., R.B. and F.J.v.d.W. have received research support from Euro Nippon Kayaku GmbH.
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References |
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