Cyclosporine in Rheumatoid Arthritis: Beyond Experimentation By David E. Yocum The
potential
toid arthritis recent
development
modalities. be made clinical then
for combined is rapidly
to stage
in this
new
patients
of such combined
other
systemic
to various
Copyright
therapy The
diseases lupus
sclerosis.
therapy such
as
erythematosus,
@ 1992
could expand scleroderma. and
by W. 6. Saunders
multiple
Company
Only be used devel-
R
HEUMATOID ARTHRITIS (RA) is a disease of unknown etiology characterized by a chronic proliferative and erosive synovitis that waxes and wanes over the lifetime of the affected individual. There is no known cure. Progressive RA has a worse prognosis than grade IV Hodgkin’s lymphoma had before the widespread use of chemotherapy.’ In spite of the significant cost this disease represents to patients and to society, little progress has been made in developing new treatments. Single-agent therapy has had limited effect, with fewer than one third of patients remaining on an individual treatment after 1 year (Table l).2 Although a greater percentage of patients remain on methotrexate therapy for more than 1 year, relatively few achieve full remission.3 There has been a growing commitment over the last 5 years to develop effective combination therapy for RA. Lessons from oncology have taught us that combined drug therapy results in more remissions than treatment with single agents and produces less toxicity. Previous attempts at combination therapy for RA have been limited, most of the studies were poorly designed, and the data collected are hard to evaluate, many having been reported only in abstract form.4-6 Consequently. it is impossible to draw conclusions from the results. Moreover, considering that the mechanism of action of most of these drugs is so poorly delineated, future efforts to combine standard slow-acting drugs may also provide little useful information beyond that known about each single drug. However, past investigations show the importance of developing well-organized studies involving suitable numbers of patients. Combinations of aggressive drugs have been investigated recently. The two most notable studies involve the use of combination cytotoxic Seminars in Arfhrhrit,s and Rheumatism,
into
must
effort
parameters. process.
the
treatment
according
combined disease
opment
in rheuma-
considering
an aggressive
immunological
can appropriate
effectively
of various
However,
and
therapy
increasing
Vol 2 1, No 6, SuppI
INDEX therapy;
WORDS:
Rheumatoid
immunomodulation;
arthritis;
combined
cyclosporine.
therapy. The first was an open study in which more than 30 patients with severe refractory RA were treated with cyclophosphamide, azathioprine, and hydroxychloroquine.’ Although more than 75% of these patients achieved remission or had a very positive response, they also suffered a high rate of neoplasia and death secondary to infection. The study suggested that combination therapy might be more effective than standard single-agent therapy, but combining two or more cytotoxic agents may result in undue morbidity and mortality. More recently, the use of combined methotrexate and azathioprine was studied at the Cleveland Clinic.7 This pilot study suggested that this combination may be more effective than either drug used individually. A multicenter study is currently examining this combination. The future of combination therapy in RA depends on the appropriate application of our understanding of the pathophysiology of this disease. Several clinical features help identify which RA patients will have a poor prognosis (Table 2).’ Nevertheless, patients with different clinical presentations, disease durations, and histological findings are too often grouped together in multicenter studies. In fact, the wide variation in therapeutic response in these studies shows the heterogeneity of subjects.
(June), 1992: pp 39-42
_
39
DAVID
Table 1: RA: Percentage
Still on Treatment
by Drug and Time
E. YOCUM
Table 3: Features of Anergic RA Patients Compared With Nonanergic Patients Anergic Patients More T cells in synovium Higher CD4-CD8 ratio in synovium Greater
synovial
lining layer hyperplasia
Less fibrin in synovium Better
Reprinted with permission.*
response
to leukapheresis
and
cyclosporine Greater
In addition to evidence provided by clinical data, recent information shows that there are at least two histological groups of RA patients (Table 3).8 One such group, characterized by lymphocyte-infiltrated synovial tissue, is associated with peripheral blood hypoproliferation to soluble recall antigens.* The second group, characterized by more fibrin and scar formation, has peripheral blood lymphocytes that respond normally to recall antigens. Not only are members of the hypoproliferative group more likely to have heavy T-cell infiltrates in their synovium, they also have a lower peripheral blood helper-to-suppressor ratio, spontaneously produce greater amounts of rheumatoid factor, have elevated levels of natural killer cells, and lack natural killer cell regulation of B-cell proliferation.8-‘0 Wahl et al showed that anergic patients were more likely to respond clinically to repeated courses of leukapheresis and, in the process, to have reversal of their anergic status. ’ ’ Several studies from around the world have shown that cyclosporine appears to be efficacious in the treatment of RA. In a study from the National Institutes of Health, Yocum et al treated anergic and nonanergic patients for 6 months in a high-dose versus low-dose comparative trial.‘*
Table 2: Predictors of Aggressive RA Rheumatoid factor seropositivity
spontaneous
rheumatoid
factor
production Poorer
natural
killer cell regulation
of B-cell
proliferation
Among patients treated with high-dose cyclosporine (mean final dose, 4.8 mg/kg per day), 10 of 15 experienced a decrease of greater than 40% in disease activity. Only 4 of 16 who received low-dose therapy (mean final dose, 0.8 mg/kg per day) experienced such a decrease. In patients receiving high-dose treatment, response was maintained for 1 year. Patients treated with low doses were much more prone to flare. When clinical responses were compared with patients’ underlying immunologic status, anergic patients were more likely than nonanergic patients to respond to cyclosporine A. “J ’ As did the data on leukapheresis, this finding suggested that anergic patients were more likely to respond to immunomodulatory intervention. Recently, Burrnester et al showed similar results in a preliminary study using anti-CD4 monoclonal antibodies in RA.13 Data from several investigators have shown that in RA patients the synoviocyte is abnormal in several ways (Table 4).14-16Not only do these cells appear histologically abnormal, but during in vitro adherent culture they grow more rapidly in early passage and form colonies in soft agar. In addition, tumorlike growth can be induced by placing these cells in nude mice. This growth appears to be regulated by various cytokines and
Rheumatoid nodules Young female patient
Table 4:
Slow onset with symmetrical
upper extremity
Paracrine Characteristics
of RA Synoviocytes
involvement Systemic
Histologically abnormal
disease
Form colonies in soft agar
Thrombocytosis Circulating immune complexes Radiographic
detection
Low educational
of erosions
level
Limited activities of daily living
Not inhibited by contact with other synoviocytes during in vitro inherent growth Induce tumors in nude mice Abnormal
growth is inhibited by retinoids
CYCLOSPORINE
Table 5: Potential Treatments Monoclonal
41
IN RA: BEYOND EXPERIMENTATION
antibodres
(animal v chimeric
for RA Y
humanized) Anti-CD4 Ant)-CD5
(-t ricrn)
Antt-MHC
class II
Ant!-T-cell Ant+IL-2
receptor receptor
Anti-tumor
necrosis
factor
Brologrcs IL-2 interferon Tumor
necrosis
factor
IL- 1 lmmunomodulating
drugs
Cyclosporine Rapamycin FK506 Other IL- 1 rnhrbitors Biologics
(cytokine,
Pseudomonas
growth
factor)
conjugated
to
exotoxin
L
growth factors, most of which are produced by the activated macrophage. Other data suggest that methotrexate may function at this level by inhibiting the macrophage.” Furthermore, the retinoids are not only anti-inflammatory agents but decrease abnormal synoviocyte growth and decrease production of growth factor.14 Close examination of the cancer literature is needed to identify agents that may be effective in limiting mesenchymal cell growth and may therefore be beneficial against RA. The development of monoclonal antibodies, especially the humanized and chimeric types, along with advances in molecular biology have provided a wide array of potentially useful tools for combination therapy for RA (Table 5).18 Such treatment modalities as anti-CDS, anti-CD4, anti-MHC class II, anti-interleukin 2 (IL-2) receptor, anti-T-cell receptor, Pseudomonas exotoxin conjugates, and various biologics are a few recent developments. In addition, the number of available immunomodulatory drugs has increased substantially. Rapamycin and FK506 are new additions to cyclosporine. Available data now allow us to predict which patients are most likely to progress and should help us to direct combined therapy. Every therapeutic modality must be tested on its own mer-
its. However, each should not be criticized too heavily for lack of efficacy as a solo agent. but only for excessive toxicity. Real success with these treatments is likely to lie in the refinement of our ability to combine them effectively with other medications in targeting multiple cell types (Table 6). Finally, early RA (duration of < 1 year) without erosions needs to be separated from early progressive (established erosions without deformity) and end-stage (significant erosions and deformities) disease. Preliminary data have shown positive effects in studies using a combination of cyclosporine and methotrexate in RA patients (Meischer, unpublished data; Tugwell. unpublished data). Previous animal studies also support these human appears effindings. IL)Although this combination fective in RA, it appears ineffective in psoriatic disease.20 Therefore. the positive or negative results of combination therapy must be evaluated for individual diseases. An example of a theoretical combined treatment program for early RA might be the use of pulses of humanized monoclonal anti-CD4 alternating with a Pscwdomonas exotoxin-IL-2 conjugate in combination with an IL- 1 inhibitor and/or cyclosporine. The strategy here would be to shut down the early cascade of inflammatory events that occur from the macrophage and the T cell. Not all of these agents would be given at once, and they would be used in sequence to suppress the abnormal immune response more effectively. In contrast, for established RA a possible combination might be humanized monoclonal anti-MHC class II or anti-tumor
Table 6: Treatments
and Cells Thev Affect
T cells Cyclosporine Ant+CD4 Anti-IL-2
receptor
IL-2-Pseudomonas
exotoxin
Macrophage IL-l -receptor Anti-MHC
antagonist class II
Methotrexate Fibroblasts
(synovrocytes)
Retrnoids Growth
factor-Pseudomonas
Methotrexate
exotoxrn
42
DAVID
necrosis factor antibodies in addition to a Pseudomonas exotoxin-growth factor conjugate and/ or an agent such as methotrexate to slow the proliferative process. Cyclosporine could be added in patients who exhibit hypoproliferative responses to recall antigens. In summary, the potential for combined therapy in RA is rapidly increasing as a result of the recent development of various treatment mo-
E. YOCUM
dalities. Nevertheless, an aggressive effort to stage patients according to clinical and immunologic parameters must be made. Only then can appropriate and effective combination therapy be designed to manage this disease process. It is possible that the development of such therapy would have implications for other diseases, including scleroderma, systemic lupus erythematosus, and multiple sclerosis.
REFERENCES 1. Pincus T, Callahan LF: Taking mortality in rheumatoid arthritis seriously-Predictive markers, socioeconomic status and comorbidity. J Rheum 13:841-845, 1986 2. Amor B, Herson D, Cherot A, et al: Follow-up study of patients with rheumatoid arthritis over a period of more than 10 years (1966-1978): Analysis of disease progression and treatment in 100 cases. Ann Med Intern 132: 168- 173, 198 1 3. Williams HJ, Willkens RF, Samuelson CO, et al: Comparison of low-dose oral pulse methotrexate and placebo in the treatment of rheumatoid arthritis: A controlled clinical trial. Arthritis Rheum 28:721-730, 1985 4. Tiliakos NA: Low-dose cytotoxic drug combination therapy in intractable rheumatoid arthritis: Two years later. Arthritis Rheum 29:S79, 1986 (abstr) 5. Bunch TW, O’DulQ JD, Tompkins RB, et al: Controlled trial of hydroxychloroquine and D-penicillamine singly and in combination in the treatment of rheumatoid arthritis. Arthritis Rheum 27:267, 1984 (abstr) 6. Csuka M, Carreara GF, McCarty DJ: Treatment of intractable rheumatoid arthritis with combined cyclophosphamide. azathioprine and hydroxychloroquine: A follow-up study. JAMA 255:23 15-23 19, 1986 7. Biro JA, Segal AM, MacKenzie AH, et al: The combination of methotrexate and azathioprine for resistant rheumatoid arthritis. Arthritis Rheum 30% 18, 1987 (abstr) 8. Malone IX, Wahl SM, Tsokos M, et al: Immune function in severe active rheumatoid arthritis: A relationship between peripheral blood mononuclear cell proliferation to soluble antigens and synovial tissue immunohistologic characteristics. J Clin Invest 74: 1173-l 185, 1984 9. Haraoui B, Wilder RL, Malone DC, et al: Immune function in severe, active rheumatoid arthritis: A relationship between peripheral blood mononuclear cell proliferation to soluble antigens and mononuclear cell subset profiles. J Immunol 133:697-70 I, 1984 10. Yocum DE, Wilder RL, Dougherty S, et al: Immunological parameters of response in patients with rheumatoid
arthritis treated with cyclosporin A. Arthritis Rheum 33: 13lo1316, 1990 11. Wahl SM, Wilder RL, Katona IM, et al: Leukapheresis in rheumatoid arthritis: Association of clinical improvement with reversal of anergy. Arthritis Rheum 26:1076-1084, 1983 12. Yocum DE, Khppel JH, Wilder RL, et al: Cyclosporin A in severe treatment-refractory rheumatoid arthritis: A randomized study. Ann Intern Med 109:863-869, 1988 13. Burmester CR, Horneff G, Emmrich F, et al: Immunomodulatory treatment of rheumatoid arthritis with an antiCD4 (anti-helper T cell) monoclonal antibody. Arthritis Rheum 33:S25, 1990 (abstr) 14. Lafyatis R, Remmers EF, Roberts AB, et al: Anchorage independent growth of synoviocytes from arthritic and normal joints: Stimulation by exogenesis platelet-derived growth factor and inhibition by transforming growth factor-beta and retinoids. J Clin Invest 83:1267-1276, 1989 15. Yocum DE, Esparza L, Dubry S, et al: Characteristics of tumor necrosis factor production in rheumatoid arthritis. Cell Immunol 122:131-145, 1989 16. Yocum DE, Esparza L, Scuderi P, et al: Characterization of transforming growth factor alpha, epidermal growth factor and the epidermal growth factor receptor in inflammatory and non-inflammatory arthritis. Arthritis Rheum 33: S150, 1990 (abstr) 17. Segal R, Mozes E, Yaron M, et al: The effects of methotrexate on the production and activity of interleukin- I. Arthritis Rheum 32:370-377, 1989 18. Herzog C, Walker C, Muller W, et al: Anti-CD4+ antibody treatment of patients with rheumatoid arthritis: 1. Effect on clinical and circulating T cells. J Autoimmun 2:627-642, 1989 19. Brahn E, Banquerigo MLC, Liu OY: Effects of tumor necrosis factor and combination cyclosporin A/methotrexate therapy on collagen arthritis. Arthritis Rheum 32:S133, 1989 (abstr D42) 20. Korstanje MJ, van Breda Vriesman CJ, van de Staak WJBM: Cyclosporine and methotrexate. A dangerous combination. Am J Dermatol 23:320-321, 1990
potential
toid arthritis recent
development
modalities. be made clinical then
for combined is rapidly
to stage
in this
new
patients
of such combined
other
systemic
to various
Copyright
therapy The
diseases lupus
sclerosis.
therapy such
as
erythematosus,
@ 1992
could expand scleroderma. and
by W. 6. Saunders
multiple
Company
Only be used devel-
R
HEUMATOID ARTHRITIS (RA) is a disease of unknown etiology characterized by a chronic proliferative and erosive synovitis that waxes and wanes over the lifetime of the affected individual. There is no known cure. Progressive RA has a worse prognosis than grade IV Hodgkin’s lymphoma had before the widespread use of chemotherapy.’ In spite of the significant cost this disease represents to patients and to society, little progress has been made in developing new treatments. Single-agent therapy has had limited effect, with fewer than one third of patients remaining on an individual treatment after 1 year (Table l).2 Although a greater percentage of patients remain on methotrexate therapy for more than 1 year, relatively few achieve full remission.3 There has been a growing commitment over the last 5 years to develop effective combination therapy for RA. Lessons from oncology have taught us that combined drug therapy results in more remissions than treatment with single agents and produces less toxicity. Previous attempts at combination therapy for RA have been limited, most of the studies were poorly designed, and the data collected are hard to evaluate, many having been reported only in abstract form.4-6 Consequently. it is impossible to draw conclusions from the results. Moreover, considering that the mechanism of action of most of these drugs is so poorly delineated, future efforts to combine standard slow-acting drugs may also provide little useful information beyond that known about each single drug. However, past investigations show the importance of developing well-organized studies involving suitable numbers of patients. Combinations of aggressive drugs have been investigated recently. The two most notable studies involve the use of combination cytotoxic Seminars in Arfhrhrit,s and Rheumatism,
into
must
effort
parameters. process.
the
treatment
according
combined disease
opment
in rheuma-
considering
an aggressive
immunological
can appropriate
effectively
of various
However,
and
therapy
increasing
Vol 2 1, No 6, SuppI
INDEX therapy;
WORDS:
Rheumatoid
immunomodulation;
arthritis;
combined
cyclosporine.
therapy. The first was an open study in which more than 30 patients with severe refractory RA were treated with cyclophosphamide, azathioprine, and hydroxychloroquine.’ Although more than 75% of these patients achieved remission or had a very positive response, they also suffered a high rate of neoplasia and death secondary to infection. The study suggested that combination therapy might be more effective than standard single-agent therapy, but combining two or more cytotoxic agents may result in undue morbidity and mortality. More recently, the use of combined methotrexate and azathioprine was studied at the Cleveland Clinic.7 This pilot study suggested that this combination may be more effective than either drug used individually. A multicenter study is currently examining this combination. The future of combination therapy in RA depends on the appropriate application of our understanding of the pathophysiology of this disease. Several clinical features help identify which RA patients will have a poor prognosis (Table 2).’ Nevertheless, patients with different clinical presentations, disease durations, and histological findings are too often grouped together in multicenter studies. In fact, the wide variation in therapeutic response in these studies shows the heterogeneity of subjects.
(June), 1992: pp 39-42
_
39
DAVID
Table 1: RA: Percentage
Still on Treatment
by Drug and Time
E. YOCUM
Table 3: Features of Anergic RA Patients Compared With Nonanergic Patients Anergic Patients More T cells in synovium Higher CD4-CD8 ratio in synovium Greater
synovial
lining layer hyperplasia
Less fibrin in synovium Better
Reprinted with permission.*
response
to leukapheresis
and
cyclosporine Greater
In addition to evidence provided by clinical data, recent information shows that there are at least two histological groups of RA patients (Table 3).8 One such group, characterized by lymphocyte-infiltrated synovial tissue, is associated with peripheral blood hypoproliferation to soluble recall antigens.* The second group, characterized by more fibrin and scar formation, has peripheral blood lymphocytes that respond normally to recall antigens. Not only are members of the hypoproliferative group more likely to have heavy T-cell infiltrates in their synovium, they also have a lower peripheral blood helper-to-suppressor ratio, spontaneously produce greater amounts of rheumatoid factor, have elevated levels of natural killer cells, and lack natural killer cell regulation of B-cell proliferation.8-‘0 Wahl et al showed that anergic patients were more likely to respond clinically to repeated courses of leukapheresis and, in the process, to have reversal of their anergic status. ’ ’ Several studies from around the world have shown that cyclosporine appears to be efficacious in the treatment of RA. In a study from the National Institutes of Health, Yocum et al treated anergic and nonanergic patients for 6 months in a high-dose versus low-dose comparative trial.‘*
Table 2: Predictors of Aggressive RA Rheumatoid factor seropositivity
spontaneous
rheumatoid
factor
production Poorer
natural
killer cell regulation
of B-cell
proliferation
Among patients treated with high-dose cyclosporine (mean final dose, 4.8 mg/kg per day), 10 of 15 experienced a decrease of greater than 40% in disease activity. Only 4 of 16 who received low-dose therapy (mean final dose, 0.8 mg/kg per day) experienced such a decrease. In patients receiving high-dose treatment, response was maintained for 1 year. Patients treated with low doses were much more prone to flare. When clinical responses were compared with patients’ underlying immunologic status, anergic patients were more likely than nonanergic patients to respond to cyclosporine A. “J ’ As did the data on leukapheresis, this finding suggested that anergic patients were more likely to respond to immunomodulatory intervention. Recently, Burrnester et al showed similar results in a preliminary study using anti-CD4 monoclonal antibodies in RA.13 Data from several investigators have shown that in RA patients the synoviocyte is abnormal in several ways (Table 4).14-16Not only do these cells appear histologically abnormal, but during in vitro adherent culture they grow more rapidly in early passage and form colonies in soft agar. In addition, tumorlike growth can be induced by placing these cells in nude mice. This growth appears to be regulated by various cytokines and
Rheumatoid nodules Young female patient
Table 4:
Slow onset with symmetrical
upper extremity
Paracrine Characteristics
of RA Synoviocytes
involvement Systemic
Histologically abnormal
disease
Form colonies in soft agar
Thrombocytosis Circulating immune complexes Radiographic
detection
Low educational
of erosions
level
Limited activities of daily living
Not inhibited by contact with other synoviocytes during in vitro inherent growth Induce tumors in nude mice Abnormal
growth is inhibited by retinoids
CYCLOSPORINE
Table 5: Potential Treatments Monoclonal
41
IN RA: BEYOND EXPERIMENTATION
antibodres
(animal v chimeric
for RA Y
humanized) Anti-CD4 Ant)-CD5
(-t ricrn)
Antt-MHC
class II
Ant!-T-cell Ant+IL-2
receptor receptor
Anti-tumor
necrosis
factor
Brologrcs IL-2 interferon Tumor
necrosis
factor
IL- 1 lmmunomodulating
drugs
Cyclosporine Rapamycin FK506 Other IL- 1 rnhrbitors Biologics
(cytokine,
Pseudomonas
growth
factor)
conjugated
to
exotoxin
L
growth factors, most of which are produced by the activated macrophage. Other data suggest that methotrexate may function at this level by inhibiting the macrophage.” Furthermore, the retinoids are not only anti-inflammatory agents but decrease abnormal synoviocyte growth and decrease production of growth factor.14 Close examination of the cancer literature is needed to identify agents that may be effective in limiting mesenchymal cell growth and may therefore be beneficial against RA. The development of monoclonal antibodies, especially the humanized and chimeric types, along with advances in molecular biology have provided a wide array of potentially useful tools for combination therapy for RA (Table 5).18 Such treatment modalities as anti-CDS, anti-CD4, anti-MHC class II, anti-interleukin 2 (IL-2) receptor, anti-T-cell receptor, Pseudomonas exotoxin conjugates, and various biologics are a few recent developments. In addition, the number of available immunomodulatory drugs has increased substantially. Rapamycin and FK506 are new additions to cyclosporine. Available data now allow us to predict which patients are most likely to progress and should help us to direct combined therapy. Every therapeutic modality must be tested on its own mer-
its. However, each should not be criticized too heavily for lack of efficacy as a solo agent. but only for excessive toxicity. Real success with these treatments is likely to lie in the refinement of our ability to combine them effectively with other medications in targeting multiple cell types (Table 6). Finally, early RA (duration of < 1 year) without erosions needs to be separated from early progressive (established erosions without deformity) and end-stage (significant erosions and deformities) disease. Preliminary data have shown positive effects in studies using a combination of cyclosporine and methotrexate in RA patients (Meischer, unpublished data; Tugwell. unpublished data). Previous animal studies also support these human appears effindings. IL)Although this combination fective in RA, it appears ineffective in psoriatic disease.20 Therefore. the positive or negative results of combination therapy must be evaluated for individual diseases. An example of a theoretical combined treatment program for early RA might be the use of pulses of humanized monoclonal anti-CD4 alternating with a Pscwdomonas exotoxin-IL-2 conjugate in combination with an IL- 1 inhibitor and/or cyclosporine. The strategy here would be to shut down the early cascade of inflammatory events that occur from the macrophage and the T cell. Not all of these agents would be given at once, and they would be used in sequence to suppress the abnormal immune response more effectively. In contrast, for established RA a possible combination might be humanized monoclonal anti-MHC class II or anti-tumor
Table 6: Treatments
and Cells Thev Affect
T cells Cyclosporine Ant+CD4 Anti-IL-2
receptor
IL-2-Pseudomonas
exotoxin
Macrophage IL-l -receptor Anti-MHC
antagonist class II
Methotrexate Fibroblasts
(synovrocytes)
Retrnoids Growth
factor-Pseudomonas
Methotrexate
exotoxrn
42
DAVID
necrosis factor antibodies in addition to a Pseudomonas exotoxin-growth factor conjugate and/ or an agent such as methotrexate to slow the proliferative process. Cyclosporine could be added in patients who exhibit hypoproliferative responses to recall antigens. In summary, the potential for combined therapy in RA is rapidly increasing as a result of the recent development of various treatment mo-
E. YOCUM
dalities. Nevertheless, an aggressive effort to stage patients according to clinical and immunologic parameters must be made. Only then can appropriate and effective combination therapy be designed to manage this disease process. It is possible that the development of such therapy would have implications for other diseases, including scleroderma, systemic lupus erythematosus, and multiple sclerosis.
REFERENCES 1. Pincus T, Callahan LF: Taking mortality in rheumatoid arthritis seriously-Predictive markers, socioeconomic status and comorbidity. J Rheum 13:841-845, 1986 2. Amor B, Herson D, Cherot A, et al: Follow-up study of patients with rheumatoid arthritis over a period of more than 10 years (1966-1978): Analysis of disease progression and treatment in 100 cases. Ann Med Intern 132: 168- 173, 198 1 3. Williams HJ, Willkens RF, Samuelson CO, et al: Comparison of low-dose oral pulse methotrexate and placebo in the treatment of rheumatoid arthritis: A controlled clinical trial. Arthritis Rheum 28:721-730, 1985 4. Tiliakos NA: Low-dose cytotoxic drug combination therapy in intractable rheumatoid arthritis: Two years later. Arthritis Rheum 29:S79, 1986 (abstr) 5. Bunch TW, O’DulQ JD, Tompkins RB, et al: Controlled trial of hydroxychloroquine and D-penicillamine singly and in combination in the treatment of rheumatoid arthritis. Arthritis Rheum 27:267, 1984 (abstr) 6. Csuka M, Carreara GF, McCarty DJ: Treatment of intractable rheumatoid arthritis with combined cyclophosphamide. azathioprine and hydroxychloroquine: A follow-up study. JAMA 255:23 15-23 19, 1986 7. Biro JA, Segal AM, MacKenzie AH, et al: The combination of methotrexate and azathioprine for resistant rheumatoid arthritis. Arthritis Rheum 30% 18, 1987 (abstr) 8. Malone IX, Wahl SM, Tsokos M, et al: Immune function in severe active rheumatoid arthritis: A relationship between peripheral blood mononuclear cell proliferation to soluble antigens and synovial tissue immunohistologic characteristics. J Clin Invest 74: 1173-l 185, 1984 9. Haraoui B, Wilder RL, Malone DC, et al: Immune function in severe, active rheumatoid arthritis: A relationship between peripheral blood mononuclear cell proliferation to soluble antigens and mononuclear cell subset profiles. J Immunol 133:697-70 I, 1984 10. Yocum DE, Wilder RL, Dougherty S, et al: Immunological parameters of response in patients with rheumatoid
arthritis treated with cyclosporin A. Arthritis Rheum 33: 13lo1316, 1990 11. Wahl SM, Wilder RL, Katona IM, et al: Leukapheresis in rheumatoid arthritis: Association of clinical improvement with reversal of anergy. Arthritis Rheum 26:1076-1084, 1983 12. Yocum DE, Khppel JH, Wilder RL, et al: Cyclosporin A in severe treatment-refractory rheumatoid arthritis: A randomized study. Ann Intern Med 109:863-869, 1988 13. Burmester CR, Horneff G, Emmrich F, et al: Immunomodulatory treatment of rheumatoid arthritis with an antiCD4 (anti-helper T cell) monoclonal antibody. Arthritis Rheum 33:S25, 1990 (abstr) 14. Lafyatis R, Remmers EF, Roberts AB, et al: Anchorage independent growth of synoviocytes from arthritic and normal joints: Stimulation by exogenesis platelet-derived growth factor and inhibition by transforming growth factor-beta and retinoids. J Clin Invest 83:1267-1276, 1989 15. Yocum DE, Esparza L, Dubry S, et al: Characteristics of tumor necrosis factor production in rheumatoid arthritis. Cell Immunol 122:131-145, 1989 16. Yocum DE, Esparza L, Scuderi P, et al: Characterization of transforming growth factor alpha, epidermal growth factor and the epidermal growth factor receptor in inflammatory and non-inflammatory arthritis. Arthritis Rheum 33: S150, 1990 (abstr) 17. Segal R, Mozes E, Yaron M, et al: The effects of methotrexate on the production and activity of interleukin- I. Arthritis Rheum 32:370-377, 1989 18. Herzog C, Walker C, Muller W, et al: Anti-CD4+ antibody treatment of patients with rheumatoid arthritis: 1. Effect on clinical and circulating T cells. J Autoimmun 2:627-642, 1989 19. Brahn E, Banquerigo MLC, Liu OY: Effects of tumor necrosis factor and combination cyclosporin A/methotrexate therapy on collagen arthritis. Arthritis Rheum 32:S133, 1989 (abstr D42) 20. Korstanje MJ, van Breda Vriesman CJ, van de Staak WJBM: Cyclosporine and methotrexate. A dangerous combination. Am J Dermatol 23:320-321, 1990
