Clinical Immunogenicity of rHuPH20, a Hyaluronidase Enabling Subcutaneous Drug Administration

Abstract

Recombinant human PH20 hyaluronidase (rHuPH20) is used to facilitate dispersion of subcutaneously delivered fluids and drugs. This report summarizes rHuPH20 immunogenicity findings from clinical trials where rHuPH20 was co-administered with SC human immunoglobulin, trastuzumab, rituximab, or insulin. Plasma samples were obtained from evaluable subjects participating in ten different clinical trials as well as from healthy plasma donors. A bridging immunoassay and a modified hyaluronidase activity assay were used to determine rHuPH20-reactive antibody titers and neutralizing antibodies, respectively. rHuPH20-binding antibody populations from selected subjects with positive titers were affinity-purified and subjected to further characterization such as cross-reactivity with endogenous PH20. Among individual trials, the prevalence of pre-existing rHuPH20-reactive antibodies varied between 3 and 12%, excepting the primary immunodeficiency (PID) studies. Incidence of treatment-induced rHuPH20 antibodies was 2 to 18%, with the highest titers (81,920) observed in PID. No neutralizing antibodies were observed. Within most trials, the kinetics of antibody responses were comparable between pre-existing and treatment-induced antibody responses, although responses classified as persistent were more common in subjects with pre-existing titers. There was no association between antibody positivity and either local or systemic adverse events. Pre-existing and treatment-induced antibody populations were of similar immunoglobulin isotypes and cross-reacted to endogenous PH20 to similar extents. No cross-reactivity to PH20 paralogs was detected. rHuPH20 induces only modest immunogenicity which has no association with adverse events. In addition, antibodies purified from baseline-positive individuals are qualitatively similar to those purified from individuals developing rHuPH20-reactive antibodies following exposure to the enzyme.Electronic supplementary materialThe online version of this article (doi:10.1208/s12248-015-9782-0) contains supplementary material, which is available to authorized users.

Recombinant Human Hyaluronidase-Facilitated Subcutaneous Immunoglobulin Infusion in Primary Immunodeficiency Diseases

“…Three of 24 pediatric patients (aged 13, 14 and 17 years) developed transient anti-rHuPH20 titers (≥1:160) that decreased over time with continued IGHy treatment [44]. Isotyping of anti-rHuPH20 antibodies showed similar ratios of IgM, IgA and IgG (isotypes IgG1, IgG2, IgG3 and IgG4) for treatment-emergent antibodies from patients in the Phase III study, compared with rHuPH20 antibodies in a baseline-positive population with pre-existing rHuPH20 antibodies ( Figure 5) [26]. Cross-reactivity immunoassays of anti-rHuPH20 antibodies and endogenous PH20 (e.g., human sperm-derived hyaluronidase) showed that IGHy does not cross-react with PH20 analogs.…”

“…An additional 2 patients developed a 1:160 titer during the extension study, for an overall rate of 18% (15 of 83 patients). Longitudinal data from 5 patients with titers >1:160 demonstrated that titers decreased over time despite continued exposure to IGHy (Figure 4) [26,39]. Three of 24 pediatric patients (aged 13, 14 and 17 years) developed transient anti-rHuPH20 titers (≥1:160) that decreased over time with continued IGHy treatment [44].…”

“…No patient in the study developed neutralizing antibodies to hyaluronidase during or after exposure to IGHy [26,39]. Of the 13 patients who developed anti-rHuPH20 binding antibodies during rHuPH20 treatment in the Phase III study, 11 patients continued into the extension study and 6 continued to have titers ≥1:160.…”

“…Therefore, it is not unexpected that anti-rHuPH20 antibodies are present in a small percentage of patients before exposure to rHuPH20. It is not known why anti-rHuPH20 antibodies are present in some untreated and otherwise healthy individuals, but it may be related to hyaluronidase activity in sperm [26]. PH20 is expressed in the adult male reproductive tract and on sperm.…”

“…To account for the presence of these antibodies at baseline, the cutoff for anti-rHuPH20 antibody positivity was defined as titers ≥1:160. One patient had a positive baseline rHuPH20 antibody titer in the Phase III study and had previously been exposed to rHuPH20 in an earlier trial in which immunogenicity was not monitored [26].…”