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Vaccines, Blood & Biologics

Review of Validation Studies - February 3, 2010 - Prevnar 13

FDA, Center for Biologics Evaluation and Research


Date: February 3, 2010

From: Michael P. Schmitt, Ph. D.
Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic, and Allergenic Products, HFM-437

Through: Drusilla Burns, Ph.D.
Chief, Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic, and Allergenic Products, HFM-434

To: Julienne Vaillancourt, Chair, Review Committee

File BLA 125324

Subject: Review of validation studies for the serological assays used to measure anti-diphtheria and anti-tetanus toxoid antibody levels in human sera.

Product: Prevnar 13™ [Pneumococcal 13-valent Conjugate Vaccine (Diphtheria CRM197 Protein)]; Wyeth Pharmaceuticals Inc.

Reference: Section;; 7.1.3, stf-dip-tet-eia-igg; Amendment/0.1, submitted 10/24/08, and IND --(b)(4)---/amendments 65 and 130.


One of the primary objectives of clinical protocols 6096A1-004 and 6096A1-3005 was to demonstrate that the immune response to antigens in the Pediarix vaccine when given concomitantly with Prevnar 13™ is non-inferior to the immune response when Pediarix is given with 7vPnC. The immune response to anti-diphtheria toxoid antibodies was measured in study 6096A1-004, while the immune response to tetanus toxoid was evaluated in study 6096A1-3005. Antibodies against the diphtheria toxoid or tetanus toxoid components were measured in serum samples obtained one month after completion of the infant series. Non-inferiority was determined by the proportion of subjects that achieved anti-diphtheria or anti-tetanus toxoid antibody titers greater than or equal to 0.1 IU/ml. Co-secondary endpoints that required toxoid titers greater than or equal to .01 IU/ml was removed from consideration after discussions with sponsor regarding the sensitivity of the serological assays.

The --------(b)(4)------------------------- a serological method developed by (b)(4), was utilized to determine anti-diphtheria and anti-tetanus toxoid antibody concentrations in serum. Validation reports for these methods were submitted and reviewed previously under IND ---(b)(4)--- An Information Request (IR) letter submitted to the sponsor on July 3, 2007 included questions and comments from CBER regarding the validation of the serological assay used to measure anti-diphtheria and ant-tetanus toxoid antibody levels. The questions and comments are provided below:

Questions and Comments contained in July 3, 2007 IR letter

1. Please provide the SOP for the (b)(4) method that will be used to determine anti-diphtheria and anti-tetanus toxoid antibodies.
2. The (b)(4) validation report is dated 2001, and many of the studies in the validation report, including the --(b)(4)-- studies, were completed several years ago. Please provide an update to you report to include data which demonstrates that the current performance of the (b)(4) is consistent with that described in the validation report.
3. Please provide your method, including acceptance criteria, for qualifying new reagents and reference materials that are used in the (b)(4). Your response should include qualification of control diphtheria toxin, antibodies and any reference and control serum that may be included in the assay.
4. A co-secondary endpoint for clinical study 6096A1-004 is anti-diphtheria toxin titers greater than or equal to 0.01 IU/ml. You indicate in the (b)(4) validation report that -------------------(b)(4)------------------------------------------------------------------------------------------------------------------------ However, only limited data is provided in the validation report to support the performance of the assay at this level. Please provide additional information that supports the precision and specificity of this assay in the antibody range of 0.01 to 0.05 IU/ml. Also, please provide data that shows that samples with antitoxin levels in the lower range of the (b)(4) assay (e.g., 0.01 to 0.03 IU/ml) have antitoxin concentrations above 0.01 IU/ml when measured using an assay, such as the ------(b)(4)----------- assay, that measures toxin neutralizing antibodies

The firm provided an acceptable response to all of these questions and comments in the IR letter in their submission of September 13, 2007 (IND ---(b)(4)--).

The information provided in this BLA regarding the validation of the diphtheria toxoid and tetanus toxoid serological assays is a summary of the information previously provided in IND (b)(4) (section, stf-dip-tet-eia-igg; Amendment/0.1, submitted 10/24/08).


The serological assays used to measure anti-diphtheria toxoid and anti-tetanus toxoid antibody levels in human serum are acceptable.

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