Efficacy and safety of an oral hydrolytic enzyme therapy in patients
with rheumatoid arthritis
Pavelka K. Efficacy and safety of an oral
hydrolytic enzyme therapy in patients with rheumatoid arthritis
Institute of Rheumatology, Prague, Czech Republic. The clinical
study report. Study No.: MU-693405.
Objectives
Efficacy and safety of an enzyme formulation (Phlogenzym®
) in the treatment of patients with RA were to be determined in this
multicentric, controlled,
double-blind, randomised, clinical trial. The efficacy and
safety of two active substances were to be compared: Phlogenzymâ
versus sulfasalazine. It had to be demonstrated in this active
control equivalence study (ACES) that oral hydrolytic enzyme therapy
is „non-inferior“ to the active control (sulfasalazine) after 9
months of treatment with reference to the Thompson’s articular index
of joint inflammation, the Arthritis Impact Measurement Scale
(AIMS), laboratory indices, X-ray-imaging, and adverse events.
Number of patients: Planned: 176 (88 per group)
Treated: 154 (Phlogenzymâ : 78; sulfasalazine: 76)
Analysed: 146 (Phlogenzymâ : 75; sulfasalazine: 71)
Diagnosis and main criteria for inclusion:
Patients of either sex
Age between 18 and 70 years
Classical RA diagnosed according to ARA criteria:
Morning stiffness of at least 1 hour
Swelling of at least 3 of 14 possible joint areas (PIPs, MCPs,
wrists, elbows, knees,
ankles, and MTPs)
Swelling of at least 1 hand joint area (wrist, MCP, or PIP)
Symmetric swelling
Subcutaneous nodules
Abnormal serum rheumatoid factor
Typical X-ray changes
Degree of activity defined by 3 of the following criteria:
ESR>28 mm 1st
CRP>15 mg/l
Spontaneous pain in at least 3 joints
Swelling and/or warmth in at least 3 joints
RA diagnosed not longer than 10 years ago
Steinbrocker function criteria II and III
Ability and willingness to meet the requirements of the study for
frequency of visits and duration of the study
Written informed consent
Test product: Phlogenzym – each patient received daily:
1st week - 3x2 tablets
2nd week – 3x2 tablets
3rd week – 3x2 tablets
4th week – end of study – 3x2 tablets
Reference therapy
Sulfasalazine 500 mg – each patient received daily:
1st week 1 antirheumatic capsule
2nd week – 2 antirheumatic capsules
3rd week – 3 antirheumatic capsules
4th week – end of study – 4 antirheumatic capsules
Efficacy results
Primary criterion:
A considerable and relevant average decrease of the Thompson's joint
index was found in both treatment groups:
Phlogenzym®: from 155.2 (SD=111.88) at baseline to 86.5 (SD=106.81)
at month 9 sulfasalazine: from 157.9 (SD=118.81) at baseline to 58.7
(SD= 79.59) at month 9.
The corresponding median decreases were -43.05% (Phlogenzym®) or
-68.18% (sulfasalazine), respectively.
The Mann Whitney statistic (P[X<Y] = 0.4155) and the lower bound of
the one-sided 95%-confidence interval (Cl95% = 0.3379) could not
prove non-inferiority (benchmark: 0.36), i.e. a small, non-trivial
but not quite relevant inferiority of Phlogenzym® versus
sulfasalazine at month 9 may be assumed. If all patients of both
groups were paired and compared with their treatment result then 59%
of all patients showed an advantage for the reference group and 41%
showed an advantage of the test group, i.e. not far from 50% which
would mean equality. The value 0.4155 was just between 0.36 (=
medium-sized or relevant difference) and 0.44 (small difference).
Thus, according to conventional benchmarks the inferiority is
non-trivial but not quite relevant. It should, however, be noted
that this inferiority does not mean that all patients are worse off
if treated with the test medication. 59% of all patients show an
advantage of the reference group and 41% show advantage of the test
group, i.e. 41 percent of patient do better with the test treatment,
not too far from 50 percent which would mean equality. Or the
relation for equality is 5 to 5 patients and we have approximately 4
patients with advantage for the test drug and 6 with advantage of
the reference drug. Just one of 5 is switched to the competitor
drug. This is a small disadvantage which might well be accepted
because of the much better tolerability of the test drug.
Subgroup analyses:
The lower bounds of the confidence intervals of the odds ratios
(using the percentage change from baseline of the Thompson's joint
index at month 9) were above the benchmark of inferiority (0.404) in
the subgroups Steinbrocker class =2, ESR £ 40 mm 1st n and > 40 mm
1st h, CRP £ 16 mg/l and > 16 mg/l, duration £ 4 years and > 4
years, and requirement of low-dose corticosteroids, i.e. hints to
non-inferiority were found for these subgroups.
Responder rates according to ACR 20:
Derived criterion "responder rates" (responder was defined
according to the 7 core set measures in the paper of the ACR; Felson
et al. 1995): There were found 31/75 (41.3%) responders in the
Phlogenzym® group and 36/71 (50.7%) in the sulfasalazine group. The
responder rate in the Phlogenzym® treatment group was considerably
better than responder rates which may be expected with placebo
treatment (e.g. 7.9 to 13.6%; see Felson et al. 1998). The responder
rates of Phlogenzym® and sulfasalazine were located between the
responder rates of auranofin (AUR: 28.8% or 23.2%) and low-dose
methotrexate (MTX: 64.7%). It is interesting that the responder rate
in the sulfasalazine treatment group agreed with the responder rate
as reported in Boers et al. 1997 (49%). Thus the study MU 693 405
produced validated and absolute results which are comparable to the
results in the specialised literature.
The Mann-Whitney statistic of the 2x2 table with the responder rates
was calculated as P(X<Y) = 0.4531 (lower bound of Cl95% = 0.3856),
that is why non-inferiority (benchmark: 0.36) might be accepted for
this 7 core set measures which are recommended by the ACR.
Secondary efficacy criteria:
The lower bound of the confidence interval of Mann Whitney
statistic were close to (³ 0.33) or above the benchmark = 0.36 with
reference to following criteria (at month 9): pain at rest,
restricted function, AIMS 2 scales (mobility, walking and bending,
arm function, self-care, household tasks, social activity, support
from family, work, level of tension, mood, satisfaction, health
perception, arthritis impact), CRP, ESR, IgA, immune complexes, and
Il-2. It should be emphasized that both treatments could reduce the
ESR considerably. CRP, however, did not change very much from
baseline to month 9 (true both for Phlogenzym® and sulfasalazine).
The closing interpretation of the different data analyses came to
the conclusion that Phlogenzym® is non-inferior to sulfasalazine
with reference to the ACR 20 standard (true for overall data sets
and several subgroups). Non-inferiority could not be proven,
however, using the Thompson's joint index at month 9 as provided in
the protocol. The responder rates of Phlogenzym® were located
between the improvements of auranofin and low-dose methotrexate.
Safety Results
Adverse events were mentioned for 15/78 (19.2%) Phlogenzym®
patients and 18/76 (23.7%) sulfasalazine patients. Adverse events
were reported for 13/61 (21.3%) female and 2/17 (11.8%) male
Phlogenzym® patients or for 16/61 (26.2%) female and 2/15 (13.3%)
male sulfasalazine patients. Related adverse events were reported
for 6/61 (9.8%) female and 1/17 (5.9%) male Phlogenzym® patients or
for 12/61 (19.7%) female and 2/15 (13.3%) male sulfasalazine
patients. There were more related adverse events in the
sulfasalazine group (14/76; 18.4%) in comparison to the Phlogenzym®
treatment group (7/78; 10.0%). Strong and related adverse events
were found in the sulfasalazine group only (5/76; 6.6%).
Gastrointestinal system disorders were the mostly mentioned body
systems with reference to the related adverse events in both
treatment groups. No serious and related adverse event occurred.
Parallel courses of the group medians of the points in time were
found in all laboratory values.
Conclusion
A considerable and relevant decrease of the Thompson's joint
index was found in both treatment groups. The Mann Whitney statistic
of primary criterion (P[X<Y] = 0.4155) and the lower bound of the
one-sided 95%-confidence interval (Cl95% = 0.3379), however, could
not prove non-inferiority (benchmark: 0.36), i.e. a small,
non-trivial but not quite relevant inferiority of Phlogenzym® versus
sulfasalazine at month 9 may be assumed. This is a small
disadvantage which might well be accepted because of the much better
tolerability of the test drug.Using the derived criterion "responder
rates" (ACR 20), there were found 31/75 (41.3%) responders in the
Phlogenzym® group and 36/71 (50.7%) in the sulfasalazine group. The
responder rate in the Phlogenzym® treatment group was considerably
better than responder rates which might be expected with placebo
treatment. Non-inferiority of Phlogenzym® might be accepted using
the ACR 20 standard.