Sirolimus in patients with clinically active systemic lupus erythematosus resistant to, or intolerant of, conventional medications: a single-arm, open-label, phase 1/2 trial

Abstract

Background: Patients with systemic lupus erythematosus have T-cell dysfunction that has been attributed to the activation of the mammalian target of rapamycin (mTOR). Rapamycin inhibits antigen-induced T-cell proliferation and has been developed as a medication under the generic designation of sirolimus. We assessed safety, tolerance, and efficacy of sirolimus in a prospective, biomarker-driven, open-label clinical trial.

Methods: We did a single-arm, open-label, phase 1/2 trial of sirolimus in patients with active systemic lupus erythematosus disease unresponsive to, or intolerant of, conventional medications at the State University of New York Upstate Medical University (Syracuse, NY, USA). Eligible participants (aged ≥18 years) had active systemic lupus erythematosus fulfilling four or more of 11 diagnostic criteria defined by the American College of Rheumatology. We excluded patients with allergy or intolerance to sirolimus, patients with life-threatening manifestations of systemic lupus erythematosus, proteinuria, a urine protein to creatinine ratio higher than 0·5, anaemia, leucopenia, or thrombocytopenia. Patients received oral sirolimus at a starting dose of 2 mg per day, with dose adjusted according to tolerance and to maintain a therapeutic range of 6-15 ng/mL. Patients were treated with sirolimus for 12 months. Safety outcomes included tolerance as assessed by the occurrence of common side-effects. The primary efficacy endpoint was decrease in disease activity, assessed using the British Isles Lupus Assessment Group (BILAG) index and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Blood samples of 56 matched healthy individuals were obtained as controls for immunobiological outcomes monitored at each visit. The primary efficacy endpoint was assessed in all patients who completed 12 months of treatment, and all patients who received at least one dose of treatment were included in the safety analyses. This trial is registered with ClinicalTrials.gov, number NCT00779194.

Findings: Between March 9, 2009, and Dec 8, 2014, 43 patients were enrolled, three of whom did not meet eligibility criteria. 11 of the 40 eligible patients discontinued study treatment because of intolerance (n=2) or non-compliance (n=9). SLEDAI and BILAG disease activity scores were reduced during 12 months of treatment in 16 (55%) of 29 patients who completed treatment. Mean SLEDAI score decreased from 10·2 (SD 5·6) at enrolment to 4·8 (4·5) after 12 months of treatment (p<0·001) and the mean total BILAG index score decreased from 28·4 (12·4) at enrolment to 17·4 (10·7) after 12 months of treatment (p<0·001). The mean daily dose of prednisone required to control disease activity decreased from 23·7 mg (SD 9·6) to 7·2 mg (2·3; p<0·001) after 12 months of treatment. Sirolimus expanded CD4⁺CD25⁺FoxP3⁺ regulatory T cells and CD8⁺ memory T-cell populations and inhibited interleukin-4 and interleukin-17 production by CD4⁺ and CD4^-CD8^- double-negative T cells after 12 months. CD8⁺ memory T cells were selectively expanded in SRI-responders. Patient liver function and lymphocyte counts were unchanged. Although HDL-cholesterol (Z=-2·50, p=0·012), neutrophil counts (Z=-1·92, p=0·054), and haemoglobin (Z=-2·83, p=0·005) were moderately reduced during treatment, all changes occurred within a range that was considered safe. Platelet counts were slightly elevated during treatment (Z=2·06, p=0·0400).

Interpretation: These data show that a progressive improvement in disease activity is associated with correction of pro-inflammatory T-cell lineage specification in patients with active systemic lupus erythematosus during 12 months of sirolimus treatment. Follow-up placebo-controlled clinical trials in diverse patient populations are warranted to further define the role of mTOR blockade in treatment of systemic lupus erythematosus.

Funding: Pfizer, the National Institutes of Health, and the Central New York Community Foundation.

Figure 1. Safety outcomes

Mean sirolimus plasma concentration (A), mean haemoglobin concentration (B), mean total WBC count (C), and mean neutrophil (D), lymphocyte (E), and platelet counts (F) were measured before treatment (visit 1) and after initiation of treatment at 1 month (visit 2), 3 months (visit 3), 6 months (visit 4), 9 months (visit 5), and 12 months (visit 6) in 40 patients with systemic lupus erythmatosus. Overall changes in safety endpoints during treatment were assessed by repeated measures analysis using a mixed-effects model logistic regression approach with exact p values indicated for each safety outcome. Changes in safety endpoints at each visit (visits 2–6) were assessed by two-tailed paired t tests relative to visit 1. Error bars show SD. WBC=white blood cell. *p<0·05. †p<0·01. ‡p<0·001.

Figure 2. Clinical efficacy outcomes

Mean SLEDAI score (A), BILAG index score (B), and daily prednisone dose (C) at baseline (visit 1) and during treatment (visits 2–6). Overall changes in SLEDAI, BILAG, and prednisone dosage during sirolimus treatment were assessed by repeated measures analysis using a mixed model logistic regression approach with exact p values indicated for each outcome. Changes in SLEDAI, BILAG, and prednisone dosage at each visit (visits 2–6) were also assessed by two-tailed paired t test relative to visit 1. (D) The proportion of patients who met responder criteria according to the SRI at visits 3–6 were compared with that at visit 2 using visit 1 as a reference point. Overall distribution of responders and non-responders for SRI at visits 2–6 were also assessed by two-tailed χ² test. Error bars show SD. SLEDAI=Systemic Lupus Erythematosus Disease Activity Index. BILAG=British Isles Lupus Assessment Group. SRI=Systemic Lupus Erythematosus Responder Index. *p<0·01. †p<0·001. ‡p<0·05.

Figure 3. BILAG-defined disease flares and selected BILAG organ domain scores and SLEDAI component scores

Proportion of patients with a flare of active lupus (a new BILAG A or two new BILAG B scores in at least one organ system; A) and a BILAG organ domain score of 3 or more for mucocutaneous disease (B), musculoskeletal disease (C) and cardiovascular and pulmonary disease (D). Mean BILAG organ domain scores for mucocutaneous disease (E), musculoskeletal disease (F), cardiovascular and pulmonary disease (G), and vasculitis (H). Mean SLEDAI score for arthritis (I), new rash (J), pyuria (K), and hypocomplementaemia (L). Scores were assessed relative to day of enrolment (before treatment, visit 1) and after treatment for 1 month (visit 2), 3 months (visit 3), 6 months (visit 4), 9 months (visit 5), and 12 months (visit 6). Effects of sirolimus were assessed by two-tailed paired t tests relative to visit 1. Overall distribution of the proportion of patients with a BILAG-defined flare (A), proportion of patients with an organ domain score of 3 or more (B–D), and overall distribution of SLEDAI components (I–L) were also assessed by χ² test. Mixed model logistic regression approach was used to analyse effect (Z-values) using repeated measures from each patient. Error bars show SD. BILAG=British Isles Lupus Assessment Group. SLEDAI=Systemic Lupus Erythematosus Disease Activity Index. *p<0·01. †p<0·05. ‡p<0·001.

Figure 4. Changes in naive CD8 T cell and memory CD8 T cells populations

Changes in expansion of naive CD8 T cells (A) and changes in memory CD8 T cells (B), as shown in fresh cells. Changes in the proportion of naive and memory CD8 T cells at each visit were assessed by two-tailed unpaired t tests relative to matched healthy controls at each timepoint and two-tailed paired t tests relative to visit 1. Error bars show SD. The number of patients (and healthy controls) contributing data differed at each visit. *p<0·01 relative to healthy matched control. †p<0·05 relative to visit 1. ‡p<0·05 relative to healthy matched control. §p<0·001 relative to healthy matched control.

Figure 5. Changes in CD8 EMT and CMT cells

Changes in CD8⁺ CD62L⁻CD197⁻EMT cells (A) and CD8⁺CD62L⁺CD197⁺ CMT cells (B) during sirolimus treatment, compared with healthy controls. Changes in CD8 EMT and CMT cells were assessed by two-tailed unpaired t test relative to matched healthy controls and by two-tailed paired t tests relative to visit 1 in each patient. Error bars show SD. (C) Orthogonal partial least squares discriminant analysis of 22 patients, for whom a complete dataset was available, shows discrimination of SRI responsive and SRI non-responsive patients by two components of immunobiological biomarkers, using complete biomarker datasets. (D) Discrimination of SRI responsive and SRI non-responsive patients on the basis of the AUC logistic regression approach. The left panel shows the AUC CI, true positive and false positive rates, and CI. The right panel shows the abundance of EMT cells in SRI responsive and SRI non-responsive patients. Black horizontal lines indicate mean values in each patient group. Vertical lines indicate range. The horizontal dotted line shows the optimum cutoff between responsive and non-responsive patients. EMT=effector memory T. CMT=central memory T. SRI=systemic lupus erythematosus responder index. AUC=area under the receiver operating characteristic curve. *p<0·05 relative to matched healthy controls. †p<0·05 relative to visit 1 in each patient.