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  • Preliminary report of a clinical trial supporting the sequential use of an attenuated E39 peptide (E39') to optimize the immunologic response to the FBP (E39+GM-CSF) vaccine

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Preliminary report of a clinical trial supporting the sequential use of an attenuated E39 peptide (E39') to optimize the immunologic response to the FBP (E39+GM-CSF) vaccine
  1. Doreen Jackson1,
  2. Na Qiao2,
  3. Julia M Greene3,
  4. Diane Hale3,
  5. John Berry3,
  6. Alfred Trappey3,
  7. Timothy Vreeland3,
  8. Guy Clifton4,
  9. Nuhad Ibrahim4,
  10. Annie Toms4,
  11. George E Peoples5 and
  12. Elizabeth A Mittendorf2
  1. Aff1 grid.416653.30000 0004 4686 9756San Antonio Military Medical Center Converse TX USA
  2. Aff2 grid.240145.60000000122914776The University of Texas MD Anderson Cancer Center Houston TX USA
  3. Aff3 grid.416653.30000 0004 4686 9756San Antonio Military Medical Center San Antonio TX USA
  4. Aff4 grid.240145.60000000122914776MD Anderson Cancer Center Houston TX USA
  5. Aff5 Cancer Vaccine Development Program San Antonio TX USA

https://doi.org/10.1186/2051-1426-3-S2-P156

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    Meeting abstracts

    Background

    Folate Binding Protein (FBP) is overexpressed in breast, endometrial, and ovarian cancers. E39 (FBP191-199, EIWTHSYKV) is an HLA-A2 restricted FBP peptide vaccine already shown to generate significant in vivo immunologic response (IR) in a Phase I/IIa trial in endometrial and ovarian cancer. We are investigating a novel vaccination series using E39 and E39' (EIWTFSTKV), an attenuated version of E39, in a Phase Ib, randomized, single-center trial (NCT020196524) evaluating IR and monitoring long-term immunity. We present the initial IR analysis to the primary vaccination series (PVS).

    Methods

    HLA-A2+ breast or ovarian cancer patients were enrolled after completion of standard of care therapy and randomized into three arms: EE-6 inoculations of E39; EE'-3 inoculations of E39 then 3 of E39'; or E'E-3 inoculations of E39' then 3 of E39. PVS includes 6 inoculations total, one every 3-4 weeks containing 250mcg GM-CSF + 500mcg peptide in the first 5 patients per arm and 1000mcg of peptide in second 5 patients. To assess the in vivo IR, local reaction(LR) was measured 48hours after each inoculation (R1-6), and delayed type hypersensitivity (DTH) was measured pre-vaccine(R0), 1 and 6-months after the PVS (RC1, RC6). Ex vivo IR was measured via dextramer assay for E39-specific CD8+ T-cells at R0, RC1, and RC6. Statistical analyses included descriptive statistics, t-test, Chi-squared, Fisher's exact test and ANOVA as appropriate.

    Results

    Thirty-two patients were enrolled (EE n=10, EE' n=11, E'E n=11), with no clinicopathologic differences between groups, or significant toxicities appreciated. In vivo LR showed a significant difference within EE and EE' arms. LR peaked in EE at R4, while EE' continued to increase in size throughout the PVS(EE p=0.04, EE' p=0.02, E'E p=0.74). An increase in in vivo DTH was observed within arm EE' from R0-RC1-RC6 (EE p=0.72, EE' p < 0.05, E'E p=0.41). Ex vivo analysis of IR revealed no significant difference between groups (p=0.39), nor within groups (EE p=0.82, EE' p=0.58, E'E p=0.49).

    Conclusion

    In this Phase Ib trial comparing three vaccination strategies in ovarian and breast cancer patients, preliminary analysis revealed E39, given sequentially with or without E39', is immunogenic. The in vivo response is enhanced with the use of the attenuated E39' after E39. This was observed in the EE' arm, this vaccination sequence producing the most prominent LR and DTH responses. Continued analysis of immunologic responses as more data is obtained will further elucidate the optimal vaccination series for the prevention of recurrence in breast and ovarian cancer.

    Trial registration

    ClinicalTrials.gov identifier NCT020196524.