Baxter International Inc. presented the results of a phase 2/3 study of its investigational 20 per cent concentration subcutaneous immunoglobulin treatment for primary immunodeficiencies (PI) during the biennial congress of the European Society for Immunodeficiencies, held in Prague.

Immunoglobulin (IG) treatment for patients with primary immunodeficiency typically requires intravenous (IV) infusions every three to four weeks or conventional subcutaneous (SC) infusions weekly or bi-weekly. Conventional subcutaneous IG treatment is associated with fewer systemic adverse events compared with IV, but requires multiple injection sites per infusion given decreased bioavailability and the need for increased volume to achieve efficacy goals.

The phase 2/3 study evaluated the efficacy, safety, tolerability and pharmacokinetics (PK) of IGSC 20 per cent in European patients at least two years old with PI. A total of 48 study participants received IGSC 16 per cent or IVIG 10 per cent for three months, followed by weekly doses of IGSC 20 per cent for up to 12 months (median of two sites per infusion). The study met its primary endpoint that measured the rate of validated acute serious bacterial infections, or VASBIs. A single event was reported during treatment with IGSC 20 per cent (pneumonia of moderate severity), which equated to a low VASBI rate of 0.022/patient-year compared with the specified threshold of one VASBI/patient-year (P<0.0001). The rate of infections with IGSC 20 per cent (without dose adjustment) was 4.38/patient-year and mean serum IgG trough levels were comparable to IGIV 10 per cent.

There were no serious adverse events (AEs) related to IG treatment. The rate of local AEs considered related to IGSC 20 per cent treatment was 0.052/infusion (17 of 48 patients). The majority of local AEs were mild in severity and the most common events were erythema, swelling, pruritus, and pain/discomfort. There were no reports of severe local or systemic AEs related to treatment. Importantly, nearly all infusions (99.8 per cent) were completed without any interruption, slowing, or stopping the infusion.

"We are encouraged by the outcomes of this study, which support our continued efforts to enhance and expand our immunology portfolio to address unmet needs across patient communities," said John Orloff, MD, vice president and global head of research and development for Baxter BioScience. "Once the global studies have been completed, this data set will form the basis for regulatory submissions in the US and Europe as we hope this will offer a new therapeutic alternative for patients with immune deficiency disorders around the world."

Results from a separate study of IGSC 20 per cent among PI patients in North America are expected to be available next year.