Evaluating the efficacy and safety of pozelimab in patients with CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy disease: an open-label phase 2 and 3 study

Complement-targeted therapeutics: Are we there yet, or just getting started?

Therapeutic interventions in the complement system, a key immune-inflammatory mediator and contributor to a broad range of clinical conditions, have long been considered important yet challenging or even unfeasible to achieve. Almost 20 years ago, a spark was lit demonstrating the clinical and commercial viability of complement-targeted therapies. Since then, the field has experienced an impressive expansion of targeted indications and available treatment modalities. Currently, a dozen distinct complement-specific therapeutics covering several intervention points are available in the clinic, benefiting patients suffering from eight disorders, not counting numerous clinical trials and off-label uses. Observing this rapid rise of complement-targeted therapy from obscurity to mainstream with amazement, one might ask whether the peak of this development has now been reached or whether the field will continue marching on to new heights. This review looks at the milestones of complement drug discovery and development achieved so far, surveys the currently approved drug entities and indications, and ventures a glimpse into the future advancements yet to come.

Pozelimab for CHAPLE disease: results from in-trial interviews and clinical outcome assessments

BACKGROUND

CD55 deficiency with hyper-activation of complement, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) disease is ultra-rare (< 100 children or young adults worldwide) and potentially fatal. The study used mixed-methods approaches to assess how pozelimab impacts the signs and symptoms of CHAPLE disease from the patient perspective by combining within-trial interviews and clinical outcome assessments (COAs) (ClinicalTrials.gov, NCT04209634).

METHODS

Interviews conducted with patients/caregivers at screening and week 24 assessed the signs and symptoms of CHAPLE disease, including those which were most bothersome, and evaluated the change. Patients/caregivers and clinicians completed the COAs; interview data contextualized the meaningfulness of change.

RESULTS

Ten patients (aged 3-19 years) were enrolled; caregivers contributed to nine interviews. Abdominal pain, diarrhea, facial and peripheral edema, nausea, and vomiting are the core signs and symptoms of CHAPLE disease (≥ 90% patients experienced pre-treatment); the most bothersome signs and symptoms were abdominal pain (n = 9) and facial edema (n = 1). All core signs and symptoms were reported as resolved at week 24 interviews. Severity on global assessments changed from "mild" to "very severe" at baseline to "no signs or symptoms" at week 24. Interview results were generally consistent with sign- or symptom-specific COA scores.

CONCLUSIONS

Patients with CHAPLE disease treated with pozelimab for 24 weeks experienced complete resolution of core signs and symptoms. Mixed-methods approaches can contextualize the patient experience (how patients feel and function) in rare disease trials.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT04209634, registered December 24, 2019, https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04209634 .

Local complement activation and modulation in mucosal immunity

The complement system is an evolutionarily conserved arm of innate immunity, which forms one of the first lines of host response to pathogens and assists in the clearance of debris. A deficiency in key activators/amplifiers of the cascade results in recurrent infection, whereas a deficiency in regulating the cascade predisposes to accelerated organ failure, as observed in colitis and transplant rejection. Given that there are over 60 proteins in this system, it has become an attractive target for immunotherapeutics, many of which are United States Food and Drug Administration-approved or in multiple phase 2/3 clinical trials. Moreover, there have been key advances in the last few years in the understanding of how the complement system operates locally in tissues, independent of its activities in circulation. In this review, we will put into perspective the abovementioned discoveries to optimally modulate the spatiotemporal nature of complement activation and regulation at mucosal surfaces.

Structure and function of therapeutic antibodies approved by the US FDA in 2023

In calendar year 2023, the United States Food and Drug Administration (US FDA) approved a total of 55 new molecular entities, of which 12 were in the class of therapeutic antibodies. Besides antibody protein drugs, the US FDA also approved another five non-antibody protein drugs, making the broader class of protein drugs about 31% of the total approved drugs. Among the 12 therapeutic antibodies approved by the US FDA, 8 were relatively standard IgG formats, 3 were bivalent, bispecific antibodies and 1 was a trivalent, bispecific antibody. In 2023, no new antibody-drug conjugates, immunocytokines or chimeric antigen receptor-T cells were approved. Of the approved antibodies, two targeted programmed cell death receptor-1 (PD-1) for orphan indications, two targeted CD20 for diffuse large B cell lymphoma, two targeted different receptors (B-cell maturation antigen [BCMA] and G-coupled protein receptor class C, group 5, member D [GPRC5D]) for treatment of multiple myeloma, and one each that targeted amyloid-β protofibrils for Alzheimer's disease, neonatal Fc receptor alpha-chain for myasthenia gravis, complement factor C5 for CD55 deficiency with hyper-activation of complement, angiopathic thrombosis and severe protein-losing enteropathy disease, interleukin (IL)-23p19 for severely active ulcerative colitis, IL-17A-F for plaque psoriasis and respiratory syncytial virus (RSV)-F protein for season-long RSV prophylaxis in infants.