Pipeline

We reported data from a randomized, double-blind, placebo-controlled Phase 2 clinical trial of mavrilimumab in GCA.

The Phase 2 trial randomized 70 patients in a 3:2 ratio to mavrilimumab 150 mg (N=42) or placebo (N=28) biweekly injected subcutaneously, co-administered with a protocol-defined 26-week oral corticosteroid taper. Patients were stratified by new onset (n=35) or relapsing/refractory (n=35) disease. 

The primary efficacy endpoint of time-to-first adjudicated GCA flare by Week 26 in all treated patients was statistically significant (Hazard Ratio = 0.38, p=0.0263). There was a 62% lower risk of flare in mavrilimumab recipients compared to placebo recipients.

The secondary efficacy endpoint of sustained remission at Week 26 in all treated patients was also statistically significant. The sustained remission rate was 33.3 percentage points higher in mavrilimumab recipients (83.2%) compared to placebo recipients (49.9%) (p=0.0038).

There were no drug-related serious adverse events, and the rates of drug-related treatment-emergent adverse events between mavrilimumab recipients and placebo recipients were similar.

Corticosteroids are the mainstay for the treatment of GCA, but approximately 50% to 70% of patients are corticosteroid refractory or corticosteroid dependent. Long-term administration of corticosteroids carries significant morbidity, especially in an elderly population such as in those with GCA. The FDA recently approved an inhibitor of IL-6 activity as an adjunct to a corticosteroid taper for the treatment of GCA; however, IL-6 production is downstream of GM-CSF and does not address all of the underlying causes of inflammation.

We are conducting a dose-ranging Phase 2b trial of vixarelimab in patients with prurigo nodularis. Data are expected in the second half of 2022.

• The Phase 2b trial is a randomized, double-blind, placebo-controlled study designed to investigate the efficacy, safety, and pharmacokinetics of vixarelimab in reducing pruritus in subjects with prurigo nodularis. The trial is expected to enroll approximately 180 patients with moderate-to-severe prurigo nodularis experiencing severe pruritus (WI-NRS ≥ 7 at the screening visit and a mean weekly WI-NRS of ≥ 7 for each of the two consecutive weeks immediately prior to randomization). Patients are required to stop antihistamines and topical treatments, including corticosteroids, for at least two weeks prior to dosing. Prurigo nodularis treatments, other than study drug, are not allowed except for rescue. Patients will be randomized in a 1:1:1:1 fashion to receive vixarelimab 540 mg, 360 mg, 120 mg, or placebo subcutaneously monthly. The primary efficacy endpoint is the percent change from baseline in the weekly-average Worst-Itch Numeric Rating Scale (WI-NRS) at Week 16. Key secondary endpoints include the proportion of patients achieving greater-than-or-equal-to 4-point weekly-average WI-NRS reduction at Week 16 and the proportion of patients achieving a 0/1 score (clear/almost clear) on the prurigo nodularis-investigator’s global assessment (PN-IGA) at Week 16.

In 2020, we reported data from a randomized, double-blind, placebo-controlled Phase 2a clinical trial of vixarelimab in patients with prurigo nodularis.

• The trial met its primary efficacy endpoint: the reduction in weekly-average WI-NRS from baseline at Week 8 was statistically significantly greater in patients who received vixarelimab versus those who received placebo. Additionally, a statistically significant percentage of vixarelimab recipients achieved a PN-IGA score of 0/1 at Week 8 compared to placebo recipients, and the majority of vixarelimab recipients showed a clinically meaningful greater-than-or-equal-to 4-point weekly-average WI-NRS reduction at Week 8. No dose-limiting adverse experiences were observed. There were no serious adverse events or atopic dermatitis flares.

We are not aware of any current therapies approved by the FDA for the treatment of PN.

• The treatment approach for PN ranges from topical corticosteroids and occlusive corticosteroid-containing bandages for patients who have milder forms of PN to systemic corticosteroids, ultraviolet phototherapy, and systemic therapies such as thalidomide, methotrexate, and cyclosporine for those patients whose conditions don’t improve on initial treatments. Patients have reported using opioid pain medications to attempt to control the disease in its most severe form.
• Based on market research, we believe ~25% to 30% of subjects are refractory to treatment.

We reported final data for our single-ascending-dose Phase 1 study in healthy volunteers for KPL-404, supporting further development in patients. KPL-404 was well tolerated and showed dose-dependent increases in concentration across cohorts. Subjects dosed with KPL-404 10 mg/kg intravenous (IV) showed full receptor occupancy through Day 71 and complete suppression of T-cell Dependent Antibody Response (TDAR) to keyhole limpet hemocyanin (KLH) challenge and rechallenge through at least Day 57. Subjects dosed with KPL-404 5 mg/kg SC showed full receptor occupancy through Day 43 and suppression of TDAR after KLH challenge through at least Day 29. Kiniksa plans to initiate a Phase 2 proof-of-concept trial of KPL-404 in the fourth quarter of 2021.

Rheumatoid arthritis was selected as a well-characterized autoimmune disease with decades of published clinical data across diverse mechanistic classes, allowing for objective evaluation in established endpoints. The pharmacokinetic lead-in of the planned trial supports characterization of chronic administration of KPL-404 in a patient population and provides optionality to evaluate the therapeutic potential of KPL-404 across a range of other autoimmune diseases with pathologies believed to be mediated by the CD40-CD154 pathway.