Alnylam Initiates ILLUMINATE-B Phase 3 Pediatric Study of Lumasiran for the Treatment of Primary Hyperoxaluria Type 1 and Presents New Positive Results from Phase 2 Open-Label Extension Study

CAMBRIDGE, Mass.–(BUSINESS WIRE)–Alnylam
Pharmaceuticals, Inc. (Nasdaq:ALNY), the leading RNAi therapeutics
company, announced today that the Company has initiated ILLUMINATE-B, a
global Phase 3 pediatric study of lumasiran, an investigational,
subcutaneously administered RNAi therapeutic in development for the
treatment of primary hyperoxaluria type 1 (PH1). The study will enroll
approximately eight patients with PH1 under six years of age. The
primary endpoint is the percent reduction in urinary oxalate from
baseline to six months. The Company expects to report initial
ILLUMINATE-B results in mid-2020.

The Company also announced new positive efficacy results from the
ongoing Phase 2 open-label extension (OLE) study of lumasiran. The
results were presented at the International Society of Nephrology (ISN)
2019 Annual Meeting held on April 13-16 in Melbourne, Australia.

“We are pleased to start the ILLUMINATE-B pediatric trial, an important
step forward in our goal to assess the safety and efficacy of lumasiran
across the PH1 age and disease severity continuum, including patients in
early infancy. This study adds to our overall clinical development plan
for lumasiran, led by our ILLUMINATE-A pivotal study with results
expected by year-end 2019,” said Pritesh J. Gandhi, PharmD, Vice
President and General Manager, Lumasiran program at Alnylam. “We are
also pleased to report new results from our Phase 2 OLE study, and are
encouraged by the consistently sustained reductions we observe in
urinary oxalate and by the overall safety profile of lumasiran observed
thus far.”

All patients (N=20) from the Phase 1/2 study of lumasiran have now
transitioned to the Phase 2 OLE study designed to evaluate long-term
safety and efficacy of lumasiran. The new Phase 2 OLE results were
reported with 18 patients dosed in the OLE as of the data cut-off date
of February 8. Patients were on a range of lumasiran doses and regimens
(1.0 mg/kg monthly, 3.0 mg/kg monthly, and 3.0 mg/kg quarterly).

There were no discontinuations from study treatment. A single patient
(1/18; 5.6 percent) reported two serious adverse events (SAEs) of
traumatic brain injury and bone contusion sustained in a car accident;
neither was assessed as related to study drug. Adverse events (AEs) were
reported in 12/18 (66.7 percent) patients. Injection site reactions were
reported in 3/18 (16.7 percent) patients; all were mild and assessed as
related to study drug. There were no clinically significant laboratory
changes.

Lumasiran demonstrated a 72 percent mean maximal reduction (range: 41-90
percent) in urinary oxalate excretion relative to Phase 1/2 baseline
values across all dose cohorts (N=9). The mean reduction relative to
baseline at Day 85 was 69 percent (N=7). Lumasiran also demonstrated a
mean maximal reduction in urinary 24-hour oxalate:creatinine ratio of 77
percent (range: 57-91 percent) relative to Phase 1/2 baseline values
across all dose cohorts (N=10). The mean reduction relative to baseline
at Day 85 was 70 percent (N=9).

To view the results presented by Alnylam at ISN 2019 Annual Meeting,
please visit www.alnylam.com/capella.