Pariglasgene brecaparvovec

Pariglasgene brecaparvovec is an adeno-associated virus serotype 8 (AAV8) based gene therapy designed to deliver a copy of the glucose-6-phosphatase (G6PC) gene with native human G6PC promoter and enhancer elements to hepatocytes, resulting in the production of normally functioning G6Pase.

Vector Distribution and Vector Shedding

Pariglasgene brecaparvovec-opnr vector DNA levels were measured and quantified in blood and various shedding matrices using a quantitative polymerase chain reaction (qPCR) assay. This assay is sensitive and specific to pariglasgene brecaparvovec-opnr vector DNA, including DNA fragments with an intact target sequence.

Nonclinical Data

Biodistribution of vector genome DNA was evaluated following a single intravenous administration of pariglasgene brecaparvovec-opnr in adult C57BL/6N mice at a dose of 1.8 × 10¹³ gc/kg. At 13 weeks post dose, vector genome DNA was detected in all major organs analyzed, with the highest quantities detected in the liver followed by lower levels in the kidney, lung, heart, gonads, and spleen. The expression of human G6PC mRNA transcripts was primarily detected in the liver, with at least 100-fold higher level than those measured in extrahepatic tissues.

Vector genome determination in blood and vector shedding in urine, stool, saliva, and semen was evaluated in mice up to 90 days following an intravenous administration of pariglasgene brecaparvovec-opnr at 1.8 × 10¹³ gc/kg. The highest concentration of vector genome DNA was found in blood followed by stool, urine, semen, and saliva. Vector genome DNA dropped below the limit of detection in saliva after 1 week, in stool and urine after 1 month, and in semen and blood after 3 months.

Clinical Data

Biodistribution of vector genome DNA in blood and vector shedding in urine, stool, and saliva were assessed in 12 patients at baseline and on follow-up (Day 2, Week 4, 6, 12, 24, 36, and 52 for blood samples, Day 4 and 12, Week 4, 6, and 12 for other urine, stool and saliva samples) until three consecutive measurements were below the limit of detection (LOD). Peak levels of vector genome DNA occurred at the first post-dose assessment on Day 2 in blood and between Day 3 and Day 13 in stool, saliva, and urine. At a dose of 6.0 × 10¹² gc/kg measured using qPCR (which is equivalent to the recommended dose of 1.0 × 10¹³ gc/kg measured using digital droplet polymerase chain reaction (ddPCR), the highest individual peak concentration of vector genome DNA observed in blood was 6.8 × 10⁷ gc/100 ng and in the stool was 1.7 × 10⁶ gc/100 ng. Blood vector genome DNA in most patients reached below the limit of detection (LOD = 10 copies of target DNA/100 ng DNA) approximately 24 weeks post infusion. Clearance of vector DNA was defined as measurement of 3 consecutive results below the limit of detection. Based on this definition, vector genome DNA was cleared from saliva within 7 weeks and from urine and stool within 13 weeks post-infusion.

Pharmacokinetics in Specific Populations

No dedicated pharmacokinetic studies using pariglasgene brecaparvovec-opnr have been conducted in special populations.

A single intravenous administration of up to 1.2 × 10¹⁴ gc/kg of pariglasgene brecaparvovec-opnr in C57BL/6 mice, followed by an observation period of up to 13 weeks, resulted in dose-dependent elevations in transaminases (ALT and AST) at Week 4 that were almost resolved by Week 13. Lymphoid hyperplasia was observed in the spleen and lymph nodes, as well as single cell necrosis/apoptosis with Kupffer cell hyperplasia in the liver, at 1.2 × 10¹⁴ gc/kg at Week 4 and was completely resolved by Week 13. Minimal neuronal degeneration in the cervical or thoracic dorsal root ganglia was observed in 2 male mice at 1.2 × 10¹⁴ gc/kg at Week 4; this change was not observed in male or female mice at Week 13.

A single intravenous administration of up to 1.3 × 10¹⁴ gc/kg of pariglasgene brecaparvovec-opnr in juvenile C57BL/6N mice, followed by an observation period of 4 or 13 weeks, resulted in moderate increases in transaminases (ALT and AST), increased spleen weights, and hepatocellular and/or single cell necrosis with mixed inflammatory cells in mice at doses of ≥1.8 × 10¹³ gc/kg at Week 4. These findings trended towards recovery or had full recovery by Week 13. These findings were observed at a dose which is approximately 11- to 12-fold above the recommended dose of 1.0 × 10¹³ gc/kg.

A single intravenous administration of up to 1.3 × 10¹⁴ gc/kg of pariglasgene brecaparvovec-opnr in cynomolgus monkeys, followed by an observation period of 26 weeks, resulted in pariglasgene brecaparvovec-opnr-related changes limited to minimal increases in ALT at Week 1 and 13 which were no longer present by Week 26.