Status: approved, marketed

Organizations involved:

Talecris Biotherapeutics Inc. – Manuf.; R&D; Tech.; USA mark.

Instituto Grifols, S.A. - Parent

NPS Pharmaceuticals Inc – Former

Bayer Corp. – Manuf.; R&D; Tech.; Former

Bayer Schering Pharma AG – Intl. mark.

Cross ref: See the entry (#743) for Immune Globulin Products. Talacris also markets Immune Globulin (IGIV)/Talecris (Gamimune) (#765).

Description: Immune Globulin Intravenous (Human) (caprylate/chromatography) or IGIV-C is an aqueous formulation of 10% highly purified immune globulin (IgG; gamma globulin) derived from Plasma (Human). Manufacturing includes a novel Caprylate/Chromatography process for virus removal/inactivation, including anion-chromatography purification steps and double viral inactivation using caprylate and low pH (acid) incubation. Upon approval, Gamunex was the first completely new IGIV in more than a decade. Gamunex contains 9-11% IgG in 0.16-02.4 M glycine (to adjust osmolality), with at least 98% of the protein content having the electrophoretic characteristics of IgG. Gamunex contains trace levels of immune globulin fragments and IgA. The distribution of IgG subclasses is similar to that of normal immune globulin/serum.

Gamunex is packaged in 10 mL (1.0 gram protein); 25 mL (2.5 g); 50 (5.0 g); 100 mL (10.0 g); and 200 mL (20 g). The measured buffer capacity is 35 mEq/L. The osmolality is 285 mOsmol/kg (close to the physiological osmolality of 285-295 mOsmol/kg). Gamunex contains no preservatives. The Fc and Fab functions of the IgG molecules are retained, but without nonspecific activation of complement or pre-Kallikrein activity. Gamunex may be stored for up to 36 months from the date of manufacture at 2-8˚C (refrigerated), or at room temperature (up to 25-77˚F) for up to six months anytime during its 36 month shelf life from the date of manufacture.

Biological.: Caprylate (caprylic acid) is a saturated medium-chain, 8-Carbon, fatty acid of plant origin. Caprylic acid is an effective precipitating agent for most plasma proteins at pH 4.8, presuming temperature and ionic strength are optimized. Residual caprylate concentration in Gamunex is <0.215 g/L (1.3 mmol/L). Caprylate and other medium chain fatty acids are considered non-toxic. Glycine is also considered non-toxic. It is a nonessential amino acid present in the body and is used as a major ingredient in intravenous alimentation products. Glycine has been used as a stabilizer in another Talecris IGIV product, Gamimune, at a level of 0.2 M since 1992. Gamunex doses of 1 g/kg correspond to 0.15 g/kg doses of glycine.

Companies.: Gamunex was originally developed, manufactured, and marketed by Bayer Corp. in the U.S. and marketed by Bayer AG internationally. Bayer Corp., CBER/FDA est. no. 0008, developed IGIV-C and built a large-scale production facility in Clayton, NC, dedicated to the production of immune globulins processed with large-scale caprylate inactivation, filtration, and ion exchange chromatography.

In April 2005, Talecris Biotherapeutics Inc., a subsidiary of NPS Pharmaceuticals Inc., acquired the blood/plasma products business of Bayer AG, including manufacturing and U.S marketing, with Bayer AG, later Bayer Schering Pharma AG, wih Bayer retaining international marketing.

In Feb. 2011, Grifols S.A./Instituto Grifols acquired Talecris Biotherapeutics.

Manufacturing: Bayer completely redesigned the IGIV manufacturing process “from scratch,” and invested over $250 million in the facility. This integrated approach to production created a more streamlined and efficient manufacturing process that reduced production time by about 70%, while enhancing the purity of the final IGIV formulation. The Gamunex C-Process departs from conventional retrofit methods by combining multiple functions into single process steps. Two of the four cold ethanol fractionation steps of the Cohn-Oncley process have been replaced by tandem anion-exchange chromatography. The IgG is not subjected to any heat, chemical, or enzymatic modification steps. The pH is adjusted to 4.0-4.5 during processing to stabilize IgG.

Plasma (Human) is subjected to fractionation with cold ethanol and purification processes to obtain immune globulin, followed by viral inactivation and stabilization. Virus inactivation and precipitation of undesired plasma components (and viruses) are integrated into the dissolving and chromatography steps, increasing the process efficiency; and novel chromatography steps further improve yield and provide high purity IgG. The IGIV-C manufacturing method differs from prior immune globulin manufacturing methods by combining virus inactivation and precipitation of plasma proteins, using caprylate, as an integral part of the processing scheme, and minimizes further manipulation of the gamma globulin solution (i.e., viral inactivation and precipitation is accomplished in one step). Inactivation of enveloped viruses requires that the bulk of pH sensitive precipitate be removed.

As described in a flow chart at www.gamunex.com, processing starts with suspended Cohn Fraction II+III and involves carylate precipitation and cloth filtration; caprylate incubation and depth filtration (primary viral inactivation step); double anion exchange chromatography; ultrafiltration/diafiltration; bulking (final adjustment of fluid content); and incubation at low pH (4.25) incubation (secondary viral inactivation step; also stabilizes IGIVl avoids the use of sugar stabilizers). The fragile immunoglobulin stays in solution during the entire production process, allowing gentler treatment that preserves the biological activity and efficacy of the IGIV.

     The process involves suspension of IgG at pH 3.8-4.5, addition of caprylic acid, and a pH shift to pH 5.0-5.2. A precipitate of contaminating proteins, lipids, viruses, and caprylate forms and is removed, while the majority of antibodies/IgG remain in solution. Sodium caprylate is again added to a final concentration >15 mM. This solution is incubated for 1 hour at 25˚C. for viral inactivation. Precipitate (mainly caprylate) is removed and the clear solution is diluted with water to reduce ionic strength.

Virus inactivation studies have confirmed that caprylate at 16 mM or 18 mM inactivates over 4 log units of bovine viral diarrhea virus (BVDV) and pseudorabies virus (both enveloped viruses) in 30 minutes at 24˚C. In April 2003, Bayer announced that caprylate viral inactivation used for manufacture of Gamunex “completely inactivated the vaccinia virus within minutes,” eliminating the risk of vaccinia virus infection from plasma donors having received smallpox vaccination.

Two ion exchange chromatography columns, e.g., Amersham Phar-macia Biotech Q & ANX resins and E. Merck TMAE Frac-togel, designed to retain IgA and IgM are used in series. A buffered solution having a conductivity >100 mM sodium chloride solution frees the retained IgA and IgM (both undesired) fractions from the column. The bound fraction is collected as highly purified IgG (>99% purity) with subclass distribution similar to the starting distribution. The solution is diafiltered and the IgG is concentrated to final formulation values.

Caprylate virus inactivation is supplemented by low pH viral inactivation. The filled vials are held at pH 4-4.35 (also reported as 4.25) for at least 21-23 days to inactivate enveloped viruses and reduce anti-complement activity.

The overall yield using this manufacturing method from dissolving the plasma-derived protein paste to the final product is 69%. This is a significant improvement over the conventional immune globulin purification process using alcohol process wash, with yields about 48%. The process minimizes the loss of IgG, and also provides a new and efficient method to obtain IgM and IgA in good yield and purity. [Note, much of the above process information has been derived/deduced from related U.S. patents].

Processes during manufacture that contribute to overall virus removal/inactivation include caprylate precipitation/cloth filtration, caprylate incubation, column chromatography and final container low pH incubation. During the caprylate precipitation/cloth filtration step. protein impurities and viruses (nonenveloped and envelopes) are precipitated by caprylate and removed by filtration through a cloth filter. Subsequent incubation with caprylate inactivates enveloped viruses. Studies show caprylate precipitation/cloth filtration results in the following log10 reductions in virus titers: HIV and pseudorabies (PRV), undetermined due to interference by caprylate; bovine diarrheal virus (BVDV), 2.4 ± 0.3; reovirus, 2.1 ± 0.4; hepatitis A virus (HAV), 2.6 ± 0.2; and porcine parvovirus (PPV), 2.2 ± 01. Caprylate incubation provides reductions in HIV, >4.5; PRV, >4.6; BVDV, >4.5; reovirus, NA (no effect), HAV, NA; and PPV, NA. Depth filtration provides reductions of HIV, PRV and BVDV, not assessable due to interference from caprylate; reovirus, >4.3; HAV, >2.0; and PRV, 3.3 ± 0.3. Column chromatography provides reductions of HIV, >3.0; PRV, >3.3; BVDV, 4.0 ± 0.3; reovirus, >4.0; HAV, >1.4; and PPV, 4.2 ± 0.2. Incubation for 21 days at low pH provides reductions of HIV, >6.5; PRV, >4.3; BVDV, 3.5 ± 0.4; reovirus, HAV and PRV, NA. Note, HIV, PRV and BVDV are enveloped viruses, and the other lack an envelope. Some mechanistic overlap occurs between the depth filtration and other steps, and Bayer chose to exclude this step from the overall virus reduction calculations. Overall, the manufacturing process provides reductions of HIV, ≥14.0; PRV, ≥12.2; BVDV, ≥14.4; reovirus, ≥6.1; HAV, >4.0 and PPV, 6.4. Viruses are monitored throughout the manufacturing process using methods including specific NAT/PCR assays.

FDA class: Biologic PLA

CBER class: Blood and Blood Derivatives

Approvals: Date = 20030827; BLA, first approval

Date = 20050817; supplemental BLA; Indication = approval of storage at room temperature (up to 25-77˚F) for up to six months anytime during its 36 month shelf life

Indications: = [full text of the "INDICATIONS AND USAGE” section of product insert/labeling]:

Primary Humoral Immunodeficiency (PI): Gamunex (Immune Globulin Intravenous (Human), 10% Caprylate/Chromatography Purified) is indicated for replacement therapy of primary immunodeficiency states in which sever impairment of antibody forming capacity had been shown, such as congenital agammaglobulinemia, common variable immunodeficiency, X-linked immunodeficiency with hyper IgM, Wiskott-Aldrich syndrome, and severe combined immunodeficiencies.

Idiopathic Thrombocytopenic Purpura (ITP): Gamunex is indicated for Idiopathic Thrombocytopenic Purpura to rapidly raise platelet counts to prevent bleeding or to allow a patients with ITP to undergo surgery.

Status: A BLA was filed by Bayer on Aug. 27, 2002 for treatment of primary immune deficiency, and approved on Aug. 27, 2003 (approval time = ,1.0 year). Gamunex was the first newly developed IGIV product to be approved by the FDA in over a decade. Gamunex was launched in the U.S. on Nov. 4, 2003. Gamimune, another IGIV product from Talecris (entry #765), was being phased out in mid-2004 to be replaced by Gamunex.

Paul Ehrlich Institute (PEI), the pharmaceutical regulatory agency in Germany, approved Gamunex on March 3, 2004 for primary immune deficiency, idiopathic thrombocytopenia purpura (ITP), Kawasaki Syndrome and Guillan-Barre Syndrome indications:, and secondary immunodeficiency due to multiple myeloma (MM), chronic lymphocytic leukemia (CLL), pediatric HIV infection, and allogenic bone marrow transplantation.

Tech. transfer: IGIV-C manufacturing process-related patents include U.S. 6,307,028 and 5,886,154, assigned to Bayer Corp. (now Talecris) In addition to lower yields compared to the caprylate precipitation/inactivation process, classical precipitation requires use of ethanol, which destabilizes the proteins, and reduced temperatures (e.g., -5˚C) are required during to increase protein stability. Ethanol is also an explosive hazard. Caprylate combined with chromatography can avoid problems of protein denaturation that can occur using ethanol, and can be done under conditions favoring protein stability.

Bayer reported (in press releases and other disclosures) that caprylate is an effective and safe alternative to solvent-detergent (S/D) treatment for inactivating and removing enveloped viruses, such as HIV and hepatitis B virus (HBV), in the manufacture of intravenous immunoglobulins (IGIVs). Bayer claimed caprylate viral inactivation offers significant benefits over the S/D method. Although effective, S/D, the viral inactivation process that has been the industry standard for plasma-based products, has some limitations in that it requires longer processing time, removal of the inactivating agents, and results in lower product yields. In addition, biological activity, critical to the effectiveness of IGIV, may be reduced in the final plasma-derived product. Caprylate is highly effective against human viruses, such as HIV and hepatitis B virus, as well as surrogate testing viruses, e.g., bovine viral diarrhea virus (model for hepatitis C virus), even at low doses. In contrast to S/D, caprylate inactivation is virtually instantaneous. Caprylate inactivates certain viruses 20–60 times faster than S/D, allowing for a higher yield and preservation of biological activity of the final IGIV product. As a naturally occurring fatty acid widely found in animal and vegetable fats, caprylate offers proven safety. It has been used at high doses for more than 50 years as a stabilizer of Albumin (Human), another plasma-derived protein, and caprylate has “an unprecedented safety and tolerability record,” including use at high doses as an energy source during total parenteral nutrition (TPN).

Trials: To support the regulatory approvals of Gamunex in the U.S., Canada, and Germany, Bayer/Talecris conducted the largest and most rigorous licensure-relevant clinical trials in IGIV history, demonstrating excellent efficacy, safety, and tolerability compared to Gamimune N, 10% in patients with primary immunodeficiency and ITP. These groundbreaking clinical trials successfully demonstrated — for the first time in IGIV history — clinical evidence for excellent efficacy and tolerability for an IGIV product.

Bayer conducted trials in over 350 patients, with most trials comparing Gamunex and Gamimune N 10%. In the 20 years of IGIV use before this study, there had never been a head-to-head comparison of this magnitude to determine product efficacy and tolerability. This included the largest clinical study ever conducted for licensure of an IGIV in primary humoral immune deficiency disease, a 9-month study of 172 patients in the U.S. and Canada (see Journal of International Immunopharmacology, Sept. 2003). The results of statistically relevant head-to-head trials in primary immunodeficiency and idiopathic thrombocytopenia purpura (ITP) showed Gamunex to provide comparable or improved efficacy and safety. The results also suggest that not all IGIVs provide similar clinical outcomes (i.e., are not generic equivalents), with Gamunex showing a “trend toward positive differences.”

In May 2004, Bayer initiated a pivotal international multi-center 100-patient trial with Gamunex for treatment of chronic inflammatory demyelinating polyneuropathy (CIDP), an acquired immune-mediated disease affecting the peripheral nervous system. The trial is designed to support regulatory approvals worldwide.

Market: The 2007 Average Wholesale Price (AWP) is $98.65/10 mL; $246.64/25mL; $493.26/50 mL; $986.52/100 mL; and $1,973.04/200 mL (Red Book, 2007).

Gamunex replaced Gamimune N in mid-2004.

R&D: Upon approval, Bayer was conducting clinical trials with Gamunex for treatment of neurological disorders, including relapsing-remitting multiple sclerosis and chronic inflammatory demyelinating polyneuropathy (CIDP). Approval for these indications:, particularly MS, would significantly expand the market for Gamunex.