Brief Report: Longitudinal Patterns of Response to Standard of Care Therapy for Systemic Lupus Erythematosus: Implications for Clinical Trial Design

Longitudinal patterns and predictors of response to standard-of-care therapy in lupus nephritis: data from the Accelerating Medicines Partnership Lupus Network

BACKGROUND

Leveraging the Accelerating Medicines Partnership (AMP) Lupus Nephritis (LN) dataset, we evaluated longitudinal patterns, rates, and predictors of response to standard-of-care therapy in patients with lupus nephritis.

METHODS

Patients from US academic medical centers with class III, IV, and/or V LN and a baseline urine protein/creatinine (UPCR) ratio ≥ 1.0 (n = 180) were eligible for this analysis. Complete response (CR) required the following: (1) UPCR < 0.5; (2) normal serum creatinine (≤ 1.3 mg/dL) or, if abnormal, ≤ 125% of baseline; and (3) prednisone ≤ 10 mg/day. Partial response (PR) required the following: (1) > 50% reduction in UPCR; (2) normal serum creatinine or, if abnormal, ≤ 125% of baseline; and (3) prednisone dose ≤ 15 mg/day.

RESULTS

Response rates to the standard of care at week 52 were CR = 22.2%; PR = 21.7%; non-responder (NR) = 41.7%, and not determined (ND) = 14.4%. Only 8/180 (4.4%) patients had a week 12 CR sustained through week 52. Eighteen (10%) patients attained a week 12 PR or CR and sustained their responses through week 52 and 47 (26.1%) patients achieved sustained PR or CR at weeks 26 and 52. Week 52 CR or PR attainment was associated with baseline UPCR > 3 (ORadj = 3.71 [95%CI = 1.34-10.24]; p = 0.012), > 25% decrease in UPCR from baseline to week 12 (ORadj = 2.61 [95%CI = 1.07-6.41]; p = 0.036), lower chronicity index (ORadj = 1.33 per unit decrease [95%CI = 1.10-1.62]; p = 0.003), and positive anti-dsDNA antibody (ORadj = 2.61 [95%CI = 0.93-7.33]; p = 0.069).

CONCLUSIONS

CR and PR rates at week 52 were consistent with the standard-of-care response rates observed in prospective registrational LN trials. Low sustained response rates underscore the need for more efficacious therapies and highlight how critically important it is to understand the molecular pathways associated with response and non-response.

Obexelimab in Systemic Lupus Erythematosus With Exploration of Response Based on Gene Pathway Co-Expression Patterns: A Double-Blind, Randomized, Placebo-Controlled, Phase 2 Trial

OBJECTIVE

Obexelimab is an investigational, bifunctional, noncytolytic monoclonal antibody that binds CD19 and FcyRIIb to inhibit B cells, plasmablasts, and plasma cells. This trial evaluated the efficacy and safety of obexelimab in the treatment of patients with systemic lupus erythematosus (SLE).

METHODS

During screening, patients with active, non-organ-threatening SLE received corticosteroid injections to ameliorate symptoms while immunosuppressants were withdrawn (≤10 mg/day prednisone equivalent and ≤400 mg/day hydroxychloroquine allowed). Patients with improved disease activity were randomized 1:1 to obexelimab 5 mg/kg intravenously or placebo once every 2 weeks until week 32 or loss of improvement (LOI).

RESULTS

In this study, 104 patients were randomized. Analysis of the primary endpoint, proportion of patients reaching week 32 without LOI, used an efficacy-evaluable (EE) population defined as patients who completed the study or withdrew for flare or treatment-related toxicity. This endpoint did not reach statistical significance: 21 of 50 obexelimab-treated patients (42.0%) versus 12 of 42 patients (28.6%) treated with a placebo (P = 0.183). Time to LOI was increased in obexelimab-treated patients versus patients treated with a placebo in the EE (hazard ratio [HR] 0.53, P = 0.025) and intention-to-treat (HR 0.59, P = 0.062) populations. In obexelimab-treated patients, B cells decreased approximately 50%, and trough concentration and inclusion in baseline gene expression clusters with high B cell pathway modules were associated with increased time to LOI. Obexelimab was associated with infusion reactions but was generally safe and well-tolerated.

CONCLUSION

Although the primary endpoint was not reached, secondary analysis showed time to LOI was significantly increased in obexelimab-treated patients, and analysis of patient subsets defined by gene expression patterns at baseline suggests a responding subpopulation.

Longitudinal gut microbiome analyses and blooms of pathogenic strains during lupus disease flares

OBJECTIVE

Whereas genetic susceptibility for systemic lupus erythematosus (SLE) has been well explored, the triggers for clinical disease flares remain elusive. To investigate relationships between microbiota community resilience and disease activity, we performed the first longitudinal analyses of lupus gut-microbiota communities.

METHODS

In an observational study, taxononomic analyses, including multivariate analysis of ß-diversity, assessed time-dependent alterations in faecal communities from patients and healthy controls. From gut blooms, strains were isolated, with genomes and associated glycans analysed.

RESULTS

Multivariate analyses documented that, unlike healthy controls, significant temporal community-wide ecological microbiota instability was common in SLE patients, and transient intestinal growth spikes of several pathogenic species were documented. Expansions of only the anaerobic commensal, Ruminococcus (blautia) gnavus (RG) occurred at times of high-disease activity, and were detected in almost half of patients during lupus nephritis (LN) disease flares. Whole genome sequence analysis of RG strains isolated during these flares documented 34 genes postulated to aid adaptation and expansion within a host with an inflammatory condition. Yet, the most specific feature of strains found during lupus flares was the common expression of a novel type of cell membrane-associated lipoglycan. These lipoglycans share conserved structural features documented by mass spectroscopy, and highly immunogenic repetitive antigenic-determinants, recognised by high-level serum IgG2 antibodies, that spontaneously arose, concurrent with RG blooms and lupus flares.

CONCLUSIONS

Our findings rationalise how blooms of the RG pathobiont may be common drivers of clinical flares of often remitting-relapsing lupus disease, and highlight the potential pathogenic properties of specific strains isolated from active LN patients.

Disease trajectory of SLE clinical endpoints and covariates affecting disease severity and probability of response: Analysis of pooled patient-level placebo (Standard-of-Care) data to enable model-informed drug development

Systemic lupus erythematosus (SLE) is an autoimmune disease affecting multiple organ systems. Many investigational agents have failed or shown only modest effects when added to standard of care (SoC) therapy in placebo-controlled trials, and only two therapies have been approved for SLE in the last 60 years. Clinical trial outcomes have shown discordance in drug effects between clinical endpoints. Herein, we characterized longitudinal disease activity in the SLE population and the sources of variability by developing a latent disease trajectory model for SLE component endpoints (Systemic Lupus Erythematosus Disease Activity Index [SLEDAI], Physician's Global Assessment [PGA], British Isles Lupus Assessment Group Index [BILAG]) and composite endpoints (Systemic Lupus Erythematosus Responder Index [SRI], BILAG-based Composite Lupus Assessment [BICLA], and Lupus Low Disease Activity State [LLDAS]) using patient-level historical SoC data from nine phase II and III studies. Across all endpoints, in predictions up to 52 weeks from the final disease trajectory model, the following baseline covariates were associated with a greater decrease in SLE disease activity and higher response to placebo + SoC: Hispanic ethnicity from Central/South America, absence of hypocomplementemia, recent SLE diagnosis, and high baseline disease activity score using SLEDAI and BILAG separately. No discernible differences were observed in the trajectory of response to placebo + SoC across different SoC medications (antimalarial and immunosuppressant such as mycophenolate, methotrexate, and azathioprine). Across all endpoints, disease trajectory showed no difference in Asian versus non-Asian patients, supporting Asia-inclusive global SLE drug development. These results describe the first population approach to support a model-informed drug development framework in SLE.

Rituximab as Maintenance Treatment for Systemic Lupus Erythematosus: A Multicenter Observational Study of 147 Patients

OBJECTIVE

The efficacy of rituximab (RTX) in systemic lupus erythematosus (SLE) is a subject of debate. This study was undertaken to investigate the outcomes of RTX treatment in a European SLE cohort, with an emphasis on the role of RTX as a maintenance agent.

METHODS

All patients with SLE who were receiving RTX as induction therapy in 4 centers were included. Patients who received a single course of RTX and those who received RTX maintenance treatment (RMT) were followed up after treatment. Disease flares during the follow-up period were defined as an increase in disease activity and the number or dose of immunosuppressive drugs.

RESULTS

Of 147 patients, 27% experienced treatment failure at 6 months. In a multivariate analysis, a low number of previous immunosuppressive therapies (P = 0.034) and low C4 levels (P = 0.008) reduced the risk of treatment failure. Eighty patients received RMT over a median of 24.5 months during which 85 relapses, mainly musculoskeletal, were recorded (1.06 per patient). At the time of the last RTX course, 84% of the patients were in remission. Twenty-eight (35%) of 80 patients never experienced a flare during RMT and had low damage accrual. Active articular disease at the time of the first RTX administration was associated with a risk of flare during RMT (P = 0.011). After RMT, relapse-free survival was similar to that in patients receiving a single RTX course (P = 0.72).

CONCLUSION

RMT is a potential treatment option for patients with difficult-to-treat disease. Relapses occur during RMT and are more likely in those with active articular disease at the time of the first RTX administration. Relapse risk after RMT remains high and apparently comparable to that seen after a single RTX course.

Evaluating duration of response to treatment in systemic lupus erythematosus clinical trials

Objective

To evaluate response duration and identify predictors of transitioning into and out of the response state in patients with SLE receiving standard of care (SoC) in 52-week clinical trials.

Methods

A multistate model (MSM) allowing for bidirectional transitions between response and non-response states was fit to data on 759 patients with SLE with active disease randomised to SoC. The probability of being in response at 52 weeks, average duration of response (sojourn time) and mean total time in response for SLE Responder Index (SRI-4, SRI-5, SRI-6) and BILAG-based Composite Lupus Assessment (BICLA) were estimated. Predictors of attainment and loss of SRI-5 response were also assessed.

Results

The MSM estimated probability of being in response at 52 weeks ranged from 42% (SRI-6) to 61% (SRI-4). Mean duration of response ranged from 20.4 weeks (BICLA) to 31.5 weeks (SRI-4). Mean total time in response was 16.4–24.8 weeks. Baseline characteristics predictive of shorter SRI-5 response duration were African descent (p=0.005), longer history of disease (p=0.03), higher anti-dsDNA antibody titres (p=0.039), lower lymphocyte count (p=0.008) and lower haemoglobin (p=0.006). Younger age (p<0.001) and higher protein/creatinine ratio (p<0.001) were associated with higher likelihood of achieving SRI-5 but also shorter response duration.

Conclusion

Factors associated with disease severity were more predictive of shorter response duration than of 52-week response status. Analysing landmark response rates and response duration using MSM may be a more powerful way to distinguish effective investigational treatments from background SoC, although this remains to be evaluated in future trials.