The study was designed to determine the sensitivity and reproducibility of recovering immunoglobulin (Ig) isotypes (IgG subclasses, IgA, IgE and IgM classes) from dried blood spots (DBS), a methodologic subcomponent of the Upstate KIDS Study. A multiplexed Luminex assay was used for IgG1/2/3/4, IgA and IgM analysis; an ELISA was used for IgE. Plasma samples from de-identified patients were used to compare the Luminex assay with nephelometry, which is routinely used to quantify IgA, IgG and IgM in clinical samples. The IgE ELISA was compared to an immunofluorescence assay. Prior to evaluation of punches from newborn dried blood spots (NDBSs), recoveries of Ig from punches of cord blood DBSs (CBDBSs) vs. plasma from the same cord bloods were compared. Although the recoveries of Ig from plasma and DBSs were not comparable, which could be due to cell lysates in the DBS samples, the analyses were reproducible. Additionally, the levels of IgA, IgG2, IgG4, and IgM recovered from CBDBSs positively correlated with those in plasma. The DBS data is a relative value since it is not equivalent to the plasma concentration. The majority of Ig concentrations recovered from 108 newborns of the Upstate KIDs Study were within the range of newborn plasma Ig levels with the exception of IgG3. The IgG4 values displayed the greatest variance with a wide range (0.01-319 mg/dl), whereas, IgG1 values had the narrowest range (85.2-960.4 mg/dl).
Background: CIGB-247, a VSSP-adjuvanted VEGF-based vaccine, was evaluated in a phase I clinical trial in patients with advanced solid tumors (CENTAURO). Vaccination with the maximum dose of antigen showed an excellent safety profile, exhibited the highest immunogenicity and was the only one showing a reduction on platelet VEGF bioavailability. However, this antigen dose level did not achieve a complete seroconversion rate in vaccinated patients. These clinical results led us to the question whether a "reserve" of untapped immune response potential against VEGF could exist in cancer patients. To address this matter, CENTAURO-2 clinical trial was conducted where antigen and VSSP dose scale up were studied, and also incorporated the exploration of aluminum phosphate as adjuvant. These changes were made with the aim to increase immune response against VEGF.
Results: The present study reports the characterization of the humoral response elicited by CIGB-247 from the combining of different antigen doses and adjuvants. Cancer patients were immunologically monitored for approximately 1 year. Vaccination with different CIGB-247 formulations exhibited a very positive safety profile. Cancer patients developed IgM, IgG or IgA antibodies specific to VEGF. Elicited polyclonal antibodies had the ability to block the interaction between VEGF and its receptors, VEGFR1 and VEGFR2. The highest humoral response was detected in patients immunized with 800 µg of antigen + 200 µg of VSSP. Off-protocol long-term vaccination did not produce negative changes in humoral response.
Conclusions: Vaccination with a human VEGF variant molecule as antigen in combination with VSSP or aluminum phosphate is immunogenic. The results of this study could contribute to the investigation of this vaccine therapy in an adequately powered efficacy trial.
Trial registration: Trial registration number: RPCEC00000155. Cuban Public Clinical Trial Registry. Date of registration: June 06, 2013. Available from: http://registroclinico.sld.cu/ .
