Page 1
Basiliximab (anti-CD25) in combination with steroids may be aneffective new treatment for steroid-resistant ulcerative colitis
T. J. CREED*, M. R. NORMAN*, C. S. J . PROBERT� , R. F. HARVEY� , I . S. SHAW� , J . SMITHSON§,
J. ANDERSON– , M. MOORGHEN**, J . GUPTA**, N. A. SHEPHERD�� , C. M. DAYAN* & S. D.
HEARING�*University Research Centre for Neuroendocrinology, Bristol Royal Infirmary, Bristol, UK; �University Division of Medicine,
Bristol Royal Infirmary, Bristol, UK; �Department of Gastroenterology, Frenchay Hospital, Bristol, UK; §Department of
Gastroenterology, Southmead Hospital, Bristol, UK; –Department of Gastroenterology, Cheltenham General Hospital,
Cheltenham, Gloucestershire, UK; **Department of Histopathology, Bristol Royal Infirmary, Bristol, UK; ��Department
of Histopathology, Gloucestershire Royal Hospital, Gloucester, UK
Accepted for publication 11 April 2003
SUMMARY
Background: Steroid resistance represents a major clin-
ical problem in the treatment of ulcerative colitis.
In vitro, interleukin-2 renders lymphocytes steroid
resistant.
Aim: To explore the therapeutic potential of interleukin-2
receptor blockade in steroid-resistant ulcerative colitis
with both in vitro measures and a pilot in vivo study.
Methods: Ten patients with steroid-resistant ulcerative
colitis received a single bolus of 40 mg of intravenous
basiliximab plus steroid treatment in an open-label,
uncontrolled, 24-week study. The outcome was
assessed using the Ulcerative Colitis Symptom Score,
rectal biopsy and Inflammatory Bowel Disease Ques-
tionnaire. Lymphocyte steroid sensitivity was measured
in vitro in 39 subjects in the presence or absence of
basiliximab.
Results: Nine of the 10 patients achieved clinical
remission within 8 weeks. At 24 weeks, seven patients
were in clinical remission. Marked improvement in the
Ulcerative Colitis Symptom Score was seen by 1 week
(P ¼ 0.004) and on rectal biopsy and Inflammatory
Bowel Disease Questionnaire by 2 weeks (both
P < 0.05). Improvements persisted to 24 weeks
(Ulcerative Colitis Symptom Score, Inflammatory Bowel
Disease Questionnaire, both P < 0.005). Eight of the
nine responders relapsed (median, 9 weeks), but
remission was re-achieved with further corticosteroids
and the addition of azathioprine. At 24 weeks, seven
patients were in full clinical remission, five off all steroid
therapy. In vitro measurement of lymphocyte steroid
sensitivity demonstrated steroid resistance in 22% of
subjects. All were rendered steroid sensitive in the
presence of basiliximab.
Conclusions: Basiliximab appears to be effective at
inducing remission in steroid-resistant ulcerative colitis.
In vitro, basiliximab also produced a dramatic increase
in lymphocyte steroid sensitivity in healthy subjects.
Confirmation in randomized controlled studies is
required.
INTRODUCTION
Up to 30% of patients with ulcerative colitis show a poor
response to steroid therapy,1, 2 and this presents a
major clinical challenge. Immunosuppressant therapies
Correspondence to: Dr C. M. Dayan, University Research Centre for Neu-
roendocrinology, Bristol Royal Infirmary, Bristol, BS2 8HW, UK.
E-mail: [email protected]
Aliment Pharmacol Ther 2003; 18: 65–75. doi: 10.1046/j.0269-2813.2003.01639.x
� 2003 Blackwell Publishing Ltd 65
Page 2
have been used for steroid-resistant ulcerative colitis,
notably ciclosporin, which can be effective in up to
50–80% of cases, although many patients subsequently
relapse and require colectomy within 6 months.3 Ciclo-
sporin can cause serious adverse reactions, such as
renal failure and fatal immunosuppression,4, 5 and
careful monitoring of patients is required, including
drug level measurement. Azathioprine has been used to
improve the maintenance of remission achieved with
ciclosporin, and ciclosporin has been used without
corticosteroids to reduce the incidence of side-effects.6
Azathioprine and 6-mercaptopurine alone are better
tolerated as immunosuppressive agents, but their slow
onset of action (3–4 months) precludes their use in
severe disease. A therapy with comparable or greater
efficacy than ciclosporin, but with a lower incidence of
serious adverse reactions, would be a useful advance in
the treatment of steroid-resistant ulcerative colitis and
may avoid the need for emergency colectomy.
Individuals who fail to respond to steroid therapy do
not necessarily have more severe disease.7 Indeed,
in vitro studies have suggested that steroid resistance
is an intrinsic property of an individual’s T lymphocytes,
independent of the presence or severity of disease.8
Lymphocyte steroid sensitivity measured in vitro has
been shown to correlate well with clinical outcome in
ulcerative colitis,9 and similar observations have been
made in other inflammatory conditions, such as
asthma,10 systemic lupus erythematosus11 and renal
transplant recipients.12 In studies on healthy individu-
als, up to 30% were found to have lymphocyte steroid
sensitivity values consistent with steroid resistance,
despite the absence of disease, and lymphocyte steroid
sensitivity remained fairly constant for a given individ-
ual over time.8
Preliminary evidence suggests a key paracrine role for
the cytokine growth factor interleukin-2 (IL-2) in the
induction of steroid resistance in T lymphocytes (T cells).
IL-2 is secreted by activated T cells and acts via the
high-affinity IL-2 receptor (IL-2R) on T cells themselves
to promote cell survival and proliferation. The IL-2R
a-chain (CD25, required for high-affinity IL-2 binding)
is absent on resting T cells, but is rapidly (although
transiently) expressed on activation. Lymphocytes from
steroid-resistant individuals appear to produce higher
levels of IL-2 than those from steroid-sensitive individ-
uals.13 Furthermore, the addition of IL-2 (and IL-4) to
steroid-sensitive lymphocytes in vitro renders them
steroid resistant.14, 15 We therefore hypothesized that
agents able to inhibit IL-2 action might act as steroid
sensitizers.
Basiliximab (Simulect, Novartis Pharmaceuticals,
Basle, Switzerland) is a commercially available chimeric
monoclonal antibody, which binds to CD25. Basiliximab
was developed as an immunosuppressive agent for use
in transplantation and has been proven to be both safe
and effective in this role in large randomized clinical
trials.16, 17 CD25 has no cytoplasmic tail, and is
therefore a good target as it is less likely to cause
cytokine release with its attendant problems. Cell
signalling is mediated by the b- and c-receptor sub-
units, driving subsequent T-cell proliferation. When
complexed with basiliximab, IL-2Rs are unable to bind
IL-2 and hence T-cell proliferation is inhibited. Studies
in renal transplantation have demonstrated that the
administration of basiliximab does not change the
expression of IL-2Rs on circulating T cells.18 IL-2R
saturations of approximately 90% have been demon-
strated in vitro on cultured T lymphocytes, and this
level of basiliximab binding was maintained for
36 ± 14 days when renal transplant patients received
basiliximab, 20 mg, 2 h before and then 4 days after
transplantation surgery.19 Although basiliximab is
generally used in combination with steroids, it has not
previously been used in autoimmune disease or consid-
ered to be particularly synergistic with steroid action.
In the current study, we aimed to explore the potential
of basiliximab to enhance the action of steroids both
in vitro and in vivo in the treatment of steroid-resistant
ulcerative colitis. We report preliminary evidence of the
remarkable clinical efficacy of basiliximab in steroid-
resistant ulcerative colitis in an open-label, uncontrolled
study. In addition, we demonstrate the in vitro effect of
basiliximab on lymphocyte steroid sensitivity in a large
number of healthy volunteers and patients with quies-
cent ulcerative colitis.
METHODS
Clinical trial
This was an open-label, uncontrolled study of basilixim-
ab for patients with steroid-resistant ulcerative colitis.
The Local Research Ethics Committees gave study
approval, and all patients gave written informed consent.
Patients with moderate and severe steroid-resistant
ulcerative colitis were enrolled. Entry to the moderate
group required an Ulcerative Colitis Symptom Score
66 T. J. CREED et al.
� 2003 Blackwell Publishing Ltd, Aliment Pharmacol Ther 18, 65–75
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(UCSS)20 of ‡6 and a Baron Score21 of ‡2, despite
treatment with prednisolone at ‡30 mg for a minimum
of 14 days. Severe colitis was defined as six or more
bloody stools per day with one or more of the following
on admission: tachycardia of > 90 beats/min, tempera-
ture of > 37.8 �C, erythrocyte sedimentation rate of
> 30 mm/h, plasma viscosity of > 1.85 mPa or haemo-
globin level of < 10.5 g/dL (Truelove and Witts
criteria22). Patients in the severe group eligible for
treatment with basiliximab either fulfilled the criteria for
a poor outcome after 3 days of intravenous hydrocor-
tisone at 400 mg/day (C-reactive protein level of
> 45 mg/L plus three bloody stools per day, or a stool
frequency of more than eight per day),2 or had an
inadequate response after 7 days of hydrocortisone
treatment (more than three stools per day or visible
blood in the stool, but not immediately requiring
surgery). Stool samples were taken to exclude signifi-
cant pathogens including Clostridium difficile.
All patients received a single intravenous infusion of
basiliximab of 40 mg over 5 min. No dose adjustment
for patient weight is required for basiliximab, and a
single 40 mg infusion has been used previously in renal
transplantation.23 In addition, all subjects continued on
prednisolone 30 mg/day (moderate group) or intraven-
ous hydrocortisone 400 mg/day (severe group) until
the stool frequency fell to three or less per day with no
visible blood. Patients in the severe group were then
changed to oral prednisolone 30 mg/day. The predn-
isolone dose for all patients was subsequently reduced
by 5 mg per week whilst they remained in remission. If
patients relapsed after achieving remission, they
remained in the study, but the dose of prednisolone
was increased to 30 mg, and azathioprine was started
at a dose of 2.5 mg/kg. All additional medications,
including 5-aminosalicylic acid, were continued.
Patients were assessed at 0, 1, 2, 4, 6 and 8 weeks and
subsequently every 4 weeks until 24 weeks. At each
visit, full blood count, urea and electrolytes, liver
function tests, glucose and C-reactive protein were
measured. The UCSS20 was assessed, and the Inflam-
matory Bowel Disease Questionnaire (IBDQ) was com-
pleted at each visit.24 Rectal biopsy was performed at 0,
2 and 4 weeks. All biopsies were performed blind and
were scored by an experienced histopathologist (NAS) at
one sitting using the scoring system of Riley et al.25 A
blood sample for lymphocyte separation and measure-
ment of lymphocyte steroid sensitivity was taken prior to
treatment with basiliximab, and 1 week after treatment.
The primary outcome was complete clinical remission
within 8 weeks of treatment, as defined by UCSS £ 2.
Secondary outcome measures included changes in
UCSS, dose of prednisolone, IBDQ score, C-reactive
protein, albumin and histological disease activity. Long-
term outcome (24 weeks) and steroid usage were also
evaluated. All adverse events were recorded, including
glucocorticoid side-effects.
In vitro lymphocyte steroid sensitivity
Lymphocyte steroid sensitivity was measured according
to a standard assay, as described previously.8 Briefly,
peripheral blood mononuclear cells were isolated by
buoyant density centrifugation and plated at 4 · 105
cells per well in 96-well plates in RPMI1640 medium
with 10% foetal calf serum (Gibco, Paisley, UK).
Lymphocyte steroid sensitivity was assessed by meas-
uring the anti-proliferative effect of increasing amounts
of dexamethasone (10)10)10)6 mol/L) in the presence
of stimulation by phytohaemagglutinin (Sigma, Poole,
UK) at a concentration of 5 lg/mL. Cultures were
incubated for 48 h at 37 �C in 5% CO2, and prolifer-
ation was measured by the uptake of tritiated thymi-
dine. Results were calculated as the counts per minute
(c.p.m.) from the mean of triplicate cultures and
presented as the percentage inhibition at 10)6 mol/L
dexamethasone [Imax ¼ (c.p.m. with phytohaemagglu-
tinin alone ) c.p.m. with dexamethasone)/c.p.m. with
phytohaemagglutinin alone · 100%]. Where indicated,
1 mg/mL of basiliximab was added, a concentration
which achieves > 90% IL-2R occupancy in vivo.26
Statistical methods
The paired t-test was used to analyse differences in
lymphocyte steroid sensitivity, IBDQ and histology
scores. The Sign test was used to analyse differences
in paired UCSS, serum albumin and C-reactive protein
scores. As this was an open-label pilot study, no formal
power calculations were performed.
RESULTS
Clinical trial
Twenty-one patients were referred for treatment. Eleven
patients were excluded for the following reasons:
insufficiently active disease (six), concomitant other
BASILIXIMAB WITH STEROIDS FOR STEROID-RESISTANT UC 67
� 2003 Blackwell Publishing Ltd, Aliment Pharmacol Ther 18, 65–75
Page 4
disease (three) (Clostridium difficile infection, alcoholism,
chronic lung disease with recurrent chest infection),
patient unwilling to adhere to trial follow-up arrange-
ments (one) and colectomy prior to enrolment (one). Of
the 10 patients treated, seven fulfilled the criteria for
moderate disease and three for severe disease. The
baseline characteristics of the patients are shown in
Table 1.
The three patients with severe ulcerative colitis were
all being treated with intravenous hydrocortisone at
enrolment. Two of these patients had received 3 days of
intravenous hydrocortisone, preceded by 1 month of
oral prednisolone. Both of these patients fulfilled day
3 criteria for a poor outcome (C-reactive protein >
45 mg/L plus three bloody stools per day). The other
patient had received 14 days of intravenous hydrocor-
tisone, preceded by 56 days of oral prednisolone. In the
moderate ulcerative colitis group, previous high-dose
therapy (‡ 30 mg prednisolone per day) had been
instituted for a median of 20 days (range, 14–23 days),
although total continuous previous prednisolone
administration at any dose was considerably longer
for all patients (median, 36 days; range, 14–365 days).
Six of the 10 patients were being considered for
colectomy because of poor response to medical therapy
at the time of entry to the study.
Initial response. Nine of the 10 (90%) patients achieved
the primary outcome of complete clinical remission
(UCSS £ 2) within 8 weeks. The remaining patient,
who had severe ulcerative colitis, required a colectomy
9 days after treatment with basiliximab, and subse-
quently made an uneventful recovery.
All nine responders demonstrated significant improve-
ment in the clinical activity score (UCSS) as early as
week 1: at week 0, median UCSS ¼ 9 (range, 7–11); at
week 1, median UCSS ¼ 3 (range, 2–5); P ¼ 0.004
(Figure 1). Figure 2 shows the dose of steroids received
by the study patients, which was reduced once remis-
sion was achieved according to the protocol.
Quality of life scores (IBDQ) also showed a rapid and
dramatic improvement (Figure 3): at week 0, mean
IBDQ ¼ 122.8; at week 2, mean IBDQ ¼ 162.6 (the
first assessment after baseline); mean difference of
paired scores, 39.8 [95% confidence interval (CI),
18.2–61.4]; P < 0.005. It should be noted that the
2-week IBDQ value is comparable with the IBDQ scores
reported for patients in complete remission (73% of
maximum theoretically attainable score).27
In line with the rapid clinical and quality of life
responses, marked changes in histological appearances
were seen from week 2 (first biopsy following basilix-
imab), with clearing of the inflammatory infiltrate in the
mucosa, resolution of cryptitis and a notable diminution
in the round cell infiltrate in the lamina propria.
Appearances at week 4 often showed fewer chronic
inflammatory cells than would be expected in normal
mucosa (Figure 4). Total histological disease activity
scores25 (assessed blind) for acute and chronic inflam-
matory changes showed significant improvements at
Table 1. Patient demographics at enrolment
Patient
Age
(years) Sex
Disease
extent
Duration of
UC (months)
Duration of continuous
steroid treatment (days)
Disease
severity Azathioprine
1 35 M Pancolitis 156 35 Moderate No
2 66 M Pancolitis 48 14 Moderate No (previously
intolerant)
3 46 F Left-sided 36 36 Moderate No
4 56 M Recto-sigmoid 120 365 Moderate Yes
5 49 M Left-sided 48 200 Severe No (previously
ineffective)
6 41 M Left-sided 72 110 Moderate Yes
7 45 F Left-sided 132 36 Moderate No
8 55 M Left-sided 60 15 Moderate No (previously
ineffective)
9* 64 M Pancolitis 1.5 30 Severe No
10 33 F Hepatic flexure 18 56 Severe No
F, female; M, male; UC, ulcerative colitis.
* Patient 9 underwent colectomy.
68 T. J. CREED et al.
� 2003 Blackwell Publishing Ltd, Aliment Pharmacol Ther 18, 65–75
Page 5
both week 2 (mean difference of paired samples, 3.22;
95% CI, 0.8–5.65; P ¼ 0.015) and week 4 (mean
difference of paired samples, 5.0; 95% CI, 0.81–9.19;
P ¼ 0.026) vs. baseline (Figure 5). Histological disease
activity scores for individual patients were improved for
nine of the 10 patients at week 2 and for seven of the 10
patients at week 4.
Longer term outcome. Eight patients relapsed (UCSS > 2)
after initially entering remission, although only one
patient had a UCSS value as high as that at enrolment
(patient 4). Relapses were seen at week 4 (patients 1
and 4), week 6 (patient 6), week 8 (patient 5), week 10
(patient 7), week 12 (patient 8), week 16 (patient 2)
and week 20 (patient 10). The median time to relapse in
these eight patients was 9 weeks. At the time of relapse,
the prednisolone doses were 0 mg (patients 2, 7, 8 and
10), 10 mg (patient 5), 15 mg (patients 1 and 4) and
20 mg (patient 6). These patients were treated with an
increased dose of oral prednisolone (30 mg) and
azathioprine therapy was initiated at 2.5 mg/kg daily.
Two of these patients were already taking azathioprine,
and one patient had previously shown intolerance to
the drug (Table 1). Two patients could not tolerate
azathioprine (patient 1 developed leucopenia and
patient 7 developed liver function disturbance — both
resolved with withdrawal of azathioprine). With this
regimen, remission was re-achieved for all but one
patient (week 8, patients 1 and 6; week 12, patients 4, 5
and 7; week 16, patient 8; week 24, patient 10). One
relapsed again when the steroid dose was reduced to
< 5 mg (patient 4). Overall, seven of the 10 patients
(70%) were in remission 24 weeks after receiving
basiliximab, four of whom were on azathioprine, and
five of whom were receiving no steroids at all.
Despite the early relapses in four of the nine patients
who initially responded, the median UCSS demonstrated
sustained improvements compared with baseline at all
time points: week 8, 0.5 (range, 0–5; P < 0.008); week
24, 0 (range, 0–7; P ¼ 0.004). Sustained improve-
ments in the mean difference of the paired IBDQ scores
were also seen throughout the study: week 4, 50.38
0 1 2 4 6 8
0
2
4
6
8
10
12
24
Week
UC
SS
Figure 1. Median Ulcerative Colitis Symptom Score (UCSS). Filled
squares represent median values and error bars denote the
interquartile range. The broken line represents clinical remission
(UCSS £ 2).
0 1 2 4 6 8 12 16 20 24
20
40
60
80
100
0
Week
Do
se o
fp
red
nis
olo
ne/
mg
Figure 2. Median steroid dose. Filled squares represent median
values and error bars denote the interquartile range. Intravenous
hydrocortisone, 400 mg, has been represented as 80 mg of
prednisolone.
0 2 4 6 8 12 16 20 240
100
200
300
Week
IBD
Q S
core
Figure 3. Median Inflammatory Bowel Disease Questionnaire
(IBDQ) score. Filled squares represent median values and error
bars denote the interquartile range.
BASILIXIMAB WITH STEROIDS FOR STEROID-RESISTANT UC 69
� 2003 Blackwell Publishing Ltd, Aliment Pharmacol Ther 18, 65–75
Page 6
(95% CI, 25.8–74.9); week 6, 51.88 (95% CI,
27.2–76.6); week 8, 55.6 (95% CI, 33.2–77.9); week
24, 62.6 (95% CI, 38.1–87.1); all P < 0.005 vs.
baseline. In addition, the mean albumin levels improved
significantly: mean albumin at baseline, 35.9 g/dL;
mean albumin at week 8, 41.1 g/dL (P < 0.05); mean
albumin at week 24, 43.3 g/dL (P < 0.05). Changes in
C-reactive protein were not statistically significant:
mean C-reactive protein at baseline, 23.1 mg/L; mean
C-reactive protein at week 24, 12.3 mg/L (P ¼ 0.69).
However, C-reactive protein values in many patients
were undetectable (< 10 mg/L) at the end of the study,
and a significant improvement might have been seen if
a highly sensitive assay had been used.
Adverse events. One patient developed pyrexia 1 week
after treatment with basiliximab which was treated with
antibiotics. Subsequently, all cultures were negative,
there was no evidence of bowel perforation and the
patient recovered completely. The following five adverse
events in five patients were recorded: mild paraesthesia
of the feet, transient photosensitivity, transient lethargy,
loin pain and upper respiratory tract infection. Many
patients had steroid side-effects (moon face, weight
increase, etc.) at entry from previous steroid use. No
increase in steroid side-effects was seen after treatment
with basiliximab and, as steroid requirements fell, the
resolution of some steroid side-effects was noted.
0 2 4
0
2
4
6
8
10
12
14
16
Week
His
tolo
gy
sco
re
Figure 5. Histology score. Scores based on Riley et al.25 Six
histological features were graded on a four-point scale: 1, acute
inflammatory cell infiltrate; 2, crypt abscesses; 3, mucin depletion;
4, surface epithelial integrity; 5, chronic inflammatory cell
infiltrate; 6, crypt architectural irregularities. Scores shown are
total scores for all features. One patient had an inadequate biopsy
at entry and one patient had a colectomy at week 2 and therefore
did not have a biopsy at week 4.
(a) (b)
Figure 4. Rectal biopsies before (week 0) (a) and after (week 4) (b) with basiliximab.
70 T. J. CREED et al.
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In vitro lymphocyte steroid sensitivity
Lymphocyte steroid sensitivity was measured in 39
healthy subjects (32 normal volunteers and seven with
quiescent ulcerative colitis) on 45 occasions. Eleven
(24%) measurements (22% of subjects, n ¼ 10) dem-
onstrated Imax < 60%, a value associated with an
intermediate or poor response to steroids in vivo in our
previous study (‘steroid resistant’; Figure 6).9 The
percentage of subjects appearing as ‘steroid resistant’
in vitro (24%) was consistent with previous observations
in healthy individuals.8 Basiliximab alone was less
potent as an anti-proliferative agent than dexametha-
sone alone. However, with basiliximab in combination
with dexamethasone, all measurements showed Imax >
60% (‘steroid sensitive’; Figure 6). Of note, all meas-
urements from ‘steroid-resistant’ individuals (Imax <
60%) were modulated to ‘steroid sensitive’. The median
percentage inhibition values were: dexamethasone
(10)6 mol/L) alone, 77.2% [interquartile range (IQR),
60.9–85.9%]; basiliximab alone, 29.4% (IQR,
10.35–44.2%); dexamethasone (10)6 mol/L) + basilix-
imab, 92.2% (IQR, 89.2–95.6%). Thus, the addition of
basiliximab increased the median inhibition of lympho-
cyte steroid sensitivity from 77.2% to 92.2%
(P < 0.0001) (Figure 6). Furthermore, at sub-maximal
doses of steroid (10)10) 10)8 mol/L), it was possible to
confirm that the interaction between basiliximab and
dexamethasone was synergistic. At 10)8 mol/L, for
example, a difference was seen between the median
suppression with dexamethasone in the presence and
absence of basiliximab even after the suppression with
basiliximab alone had been subtracted from the former
(32.6% vs. 20.5%, n ¼ 45, P < 0.001).
At trial entry, the mean inhibition of lymphocyte
steroid sensitivity with dexamethasone in the study
subjects with active disease was 58%, and 50% fulfilled
the in vitro criteria for steroid resistance. Hence, the
frequency of steroid-resistant individuals was approxi-
mately twice that seen in the healthy population. This is
consistent with previous observations as, although the
lymphocyte steroid sensitivity measured in vitro corre-
lates with the failure to respond adequately to steroids
in vivo, it is not an absolute predictor.9 After the
addition of basiliximab in vitro, Imax increased in all
subjects and the mean lymphocyte suppression
increased to 79.1%. Two of the 10 subjects remained
steroid resistant (Imax of 41.6% and 59%). Both of these
patients achieved remission. The subject who was
marginally steroid resistant (patient 6, Imax ¼ 59%)
had only a brief relapse at 6 weeks and remained in
remission for the remainder of the study. However, the
patient with the lowest Imax value (41.6%, patient 4)
had an early relapse at week 4, achieved remission
again at 12 weeks, but relapsed again before the end of
the study. In vivo treatment with basiliximab did not
significantly alter the in vitro lymphocyte steroid
sensitivity levels (P ¼ 0.19). This might be expected,
as less than 10% of lymphocytes in the peripheral blood
spontaneously express IL-2R in vivo (although 100% do
so after in vitro activation by phytohaemagglutinin).
Hence, the majority of blood T lymphocytes would not
have bound basiliximab from the serum.
DISCUSSION
Treatment with basiliximab plus glucocorticoids in vivo
led nine of the 10 patients with steroid-resistant
ulcerative colitis to achieve complete clinical remission
within 8 weeks, and in vitro led 100% of healthy
individuals and 80% of patients to achieve the criteria
for steroid sensitivity. Seven of the 10 patients were in
remission at 24 weeks after treatment with basiliximab,
including two of the three patients who initially had
severe ulcerative colitis. Five of the patients in remission
at 24 weeks were not taking any steroids, with the
other two patients taking 5 and 10 mg of prednisolone,
respectively. The patient on 10 mg was able to with-
draw steroids altogether 2 weeks after finishing the trial
follow-up, and the other patient was maintained in
remission on 5 mg daily. Four of the patients in
60
Dex Bas Dex+Bas
-25
0
25
50
75
100
60
Drugs added to cell culture
Max
imu
m %
su
pp
ress
ion
of
lym
ph
ocy
te p
rolif
erat
ion
(I m
ax)
Figure 6. In vitro modulation of lymphocyte steroid sensitivity:
dexamethasone alone, basiliximab alone and dexamethasone plus
basiliximab. Dex, dexamethasone (10)6 mol/L); Bas, basiliximab
(1 mg/L); Imax ¼ 60%.
BASILIXIMAB WITH STEROIDS FOR STEROID-RESISTANT UC 71
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Page 8
remission were on a maintenance dose of azathioprine.
Importantly, many of these patients had experienced
active disease for up to 1 year prior to study entry,
requiring prolonged therapy with high-dose steroids. Six
of the 10 patients overall were being considered for a
colectomy because of a poor response to medical
therapy. In contrast with these results, data from
previous studies have indicated that patients with active
moderate ulcerative colitis, despite 14 days of predniso-
lone (30 mg/day), would be expected to have a response
rate of, at most, 30% after 8 weeks with continued
prednisolone therapy alone.28 In severe ulcerative
colitis, patients with poor predictors of outcome similar
to those described in this study, have been shown to
have a chance of only 15% of avoiding a colectomy on
admission.2
In addition to the primary outcome of clinical remis-
sion at 8 weeks, a single treatment with basiliximab
resulted in significant clinical improvement in all
patients within 1 week (UCSS), confirmed symptomatic
improvement within 2 weeks (IBDQ score) and marked
histological improvement within 4 weeks. The blind
histological review clearly demonstrated a statistically
significant reduction in acute inflammatory scores.
However, there was also a notable diminution in the
round cell infiltrate in the lamina propria. Indeed, in
most cases, in the week 4 biopsy, this was less than
would be expected for normal colorectal mucosa. Thus,
basiliximab in combination with steroids not only
reduced the active inflammation, but also resulted in a
striking reduction in the chronic inflammation charac-
teristically associated with chronic ulcerative colitis.
Significant improvements in albumin levels were also
seen. C-reactive protein levels showed a trend towards
improvement, but this did not reach statistical signifi-
cance.
Our in vitro data suggest that basiliximab can act as a
steroid sensitizer. Basiliximab with dexamethasone
demonstrated a greater anti-proliferative effect than
either agent alone and, at sub-maximal concentrations
of dexamethasone, it was possible to see that the
addition of basiliximab had an effect that was greater
than the sum of the steroid and basiliximab effects
alone. Basiliximab has been given alone in some clinical
settings with mixed results,29–33 and our data do not
completely exclude an action of basiliximab alone.
However, our data suggest that, as a sole agent, it is
less effective than in combination with steroids. Basil-
iximab was generally very well tolerated, as seen in
previous trials in transplantation. However, hypersen-
sitivity has been reported with the use of basiliximab,
notably after repeated administration.34 Hence, patients
must be observed for 2 h after administration. Repeated
use may result in sensitization, and cannot be recom-
mended at present. Furthermore, repeated use of
basiliximab may theoretically result in the formation
of human anti-chimeric antibodies, with a resultant
decrease in efficacy, as has been seen with the use of
anti-tumour necrosis factor treatments.
A particularly attractive feature of anti-CD25 (anti-IL-
2R) therapy is that its steroid-sensitizing action is likely
to be restricted to the immune system, as only
leucocytes express CD25 and are IL-2 dependent. No
increase in steroid side-effects is expected in other
tissues (e.g. impaired glucose tolerance, osteoporosis,
hypertension, weight gain or skin change), and this was
reflected in the findings of this study. In effect,
basiliximab is expected to make the action of steroids
more ‘lymphocyte specific’ and, as such, might benefit
steroid-sensitive as well as steroid-resistant individuals
by permitting a reduction in steroid dose.
Our data demonstrate a promising short-term (8-week)
response to basiliximab, but relapses occurred later in
all but one patient. This is not unexpected given the
pharmacokinetics of basiliximab (T1/2 ¼ 13.4 days;
duration of IL-2R saturation in adults, 4–6 weeks).26
The relapse after approximately 8 weeks in some
patients is consistent with the expected time course of
IL-2R blockade by basiliximab after a single dose.
However, in the patients who relapsed, remission was
easily re-achieved with an increase in steroid dose to
30 mg of prednisolone and/or the addition of azathiop-
rine in all but one patient. This response was striking in
a group of patients who had previously failed prolonged
high-dose steroid treatment. After 24 weeks of follow-
up, seven of the 10 patients remained in remission, with
the majority requiring no steroid treatment. Thus, we
envisage that basiliximab may have a role in the rapid
induction of remission and the avoidance of colectomy,
but alternative therapies may be required to maintain
remission, analogous to the emerging role of infliximab
in Crohn’s disease.35 An ‘8-week window’ of remission
following treatment with basiliximab may be sufficient
to allow 6-mercaptopurine or azathioprine to take effect.
Sub-group analysis may reveal which patient charac-
teristics are associated with the most favourable out-
come from basiliximab treatment, but this study was too
small to draw such conclusions.
72 T. J. CREED et al.
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Page 9
During the preparation of the manuscript, the results
of a pilot study of daclizumab (Zenepax, Roche Phar-
maceuticals, Basel, Switzerland), an alternative IL-2R
monoclonal antibody, for the treatment of medically
resistant ulcerative colitis were published.36 In this
study, no overall histological improvement was seen up
to 8 weeks (although there was a reduction in CD25-
positive cells in the mucosa), and clinical remission was
achieved in only five of 10 patients. No data on the
clinical progress beyond 8 weeks were given. Import-
antly, however, only four patients were treated with
oral steroids during this study. Thus, daclizumab was
not used as a steroid-sensitizing agent for steroid-
resistant patients, but as an alternative immunosup-
pressant. We believe that this may explain the greater
efficacy seen in our study (50% initial remission rate for
daclizumab, compared with 90% remission with basil-
iximab plus steroids). If true, this supports the view that,
although CD25 inhibition has immunosuppressant
properties alone, it works best in this context as a
steroid-sensitizing agent. However, differences between
the two monoclonal antibodies, as seen with the use of
different anti-tumour necrosis factor agents in Crohn’s
disease, may also be responsible for the different
efficacies seen.
The in vitro data in this paper relate to the effects of
basiliximab and steroids on peripheral blood mononu-
clear cells, rather than colonic mucosal lymphocytes.
However, there are increasing data indicating that
steroid resistance in lymphocytes is a generalized
phenomenon, affecting all lymphocytes, and that the
degree of ‘generalized’ steroid resistance correlates with
the response to steroids in disease. Data in ulcerative
colitis,9 systemic lupus erythematosus11 and asthma10
support this concept. This correlation between periph-
eral blood lymphocyte steroid sensitivity and clinical
response to steroid therapy suggests that it may be
meaningful to measure generalized steroid resistance in
lymphocytes as an important predictor of outcome in
response to steroid therapy. However, further studies
should be performed to investigate steroid resistance in
mucosal lymphocytes, which may indeed differ in some
aspects.
The molecular mechanism of steroid resistance in
inflammatory disease remains unclear. The glucocorti-
coid receptor (GR) exists in different isoforms. GR-a is
the predominant form and is physiologically active.
GR-b is a truncated splice variant and does not bind
glucocorticoid. GR-b mRNA is detectable in many
patients with steroid-resistant ulcerative colitis (83%),
compared with patients with steroid-sensitive ulcerative
colitis (9%), and the presence of GR-b has been
suggested as a mechanism of steroid resistance.37
However, GR-b mRNA was only found in small
amounts (< 0.2% compared with GR-a), suggesting
that it may be a marker for steroid-resistant disease
rather than the cause.38 Our data suggest a role for
IL-2, and are consistent with previous studies.14
Binding of IL-2 to its receptor results in the activation
of Janus kinases (JAK1 and JAK3), which then leads to
the activation of signal transducer and activator of
transcription 5 (STAT5).39 Other signalling pathways
activated by the receptor include the mitogen-activated
protein kinases, extracellular signal-regulated kinase
(ERK), p38 and c-Jun N-terminal kinase (JNK)
(Figure 7).
Each of these signalling molecules has been shown to
interfere with the activity of GR and, in several cases,
the inhibition is mutual (Figure 7). Thus, STAT5
inhibits transactivation by GR,40, 41 as do ERK,42, 43
JNK43 and p38.15 It seems reasonable to speculate,
therefore, that the resistance of lymphocytes to gluco-
corticoids can result from the activation of one or more
signalling pathways by IL-2R, and that basiliximab
reverses this process by inhibiting IL-2 signalling. Our
JAK3JAK1
P38, JNKP38, JNKERKERK
NFNFκBBSTAT5STAT5
AP1AP1
PI3KPI3KAktAkt
ProliferationCytokine productionInflammation
Apoptosis
INTERLEUKIN-2 GLUCOCORTICOID(cortisol, dexamethasone etc)
κ
Figure 7. Interleukin-2 (IL-2) and glucocorticoid signalling in
activated T cells. Cross-talk between IL-2 and glucocorticoid
signalling pathways. Signalling molecules extracellular signal-
regulated kinase (ERK), p38, c-Jun N-terminal kinase (JNK),
signal transducer and activator of transcription 5 (STAT5),
nuclear factor kappa B (NFjB) and activator protein-1 (AP1) are
activated by the IL-2 receptor, and all have been shown to
interfere with glucocorticoid signalling (conversely, the gluco-
corticoid receptor has also been shown to interfere with STAT5,
NFjB and AP1). Akt, AKT virus protein kinase; JAK, Janus
kinase; PI3K, phosphoinositide 3-kinase.
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data do not exclude the possibility that basiliximab acts
independently of steroids to suppress ulcerative colitis.
However, the presence of multiple proven interactions
between the IL-2 and glucocorticoid signalling path-
ways, the limited effect of basiliximab alone on lym-
phocyte steroid sensitivity in vitro (Figure 6), the
pharmacological synergy seen with glucocorticoids at
intermediate doses in vitro and the limited effects of anti-
CD25 blockade when not directly combined with
steroids in vivo36 make this unlikely. Indeed, the
impressive synergistic effect of basiliximab with steroids
on lymphocyte steroid sensitivity in vitro, even in
healthy volunteers, supports the idea that it may be
effective in T-cell-dependent inflammatory conditions
other than ulcerative colitis.
In conclusion, the data presented here provide prelim-
inary evidence that basiliximab in combination with
glucocorticoids is a very effective and well-tolerated
treatment for the induction of remission in steroid-
resistant ulcerative colitis. When used in combination
with other slower acting treatments (such as azathiop-
rine or 6-mercaptopurine), we envisage that anti-CD25
therapy may avoid the need for surgery in the majority
of patients with steroid-resistant disease, and may also
reduce the incidence of steroid-related side-effects.
Further controlled trials are now required to confirm
these promising findings.
ACKNOWLEDGEMENTS
We are grateful to two patients who supplied personal
donations to provide initial funding for the in vitro
studies, and to Marcus Arden-Jones and David Youds
(Novartis Pharmaceuticals, Frimley, UK) for providing
support to the study.
A project grant to fund a research salary (TJC) and
basiliximab for the in vitro study and the clinical trial
were supplied by Novartis Pharmaceuticals. Three
authors (SDH, MNN, CMD) have lodged a patent
application for the use of basiliximab as a steroid
sensitizer.
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