Clinical study of a survivin long peptide vaccine (SurVaxM) in patients with recurrent malignant glioma

Abstract

Survivin is an anti-apoptotic protein that is highly expressed in many cancers, including malignant gliomas. Preclinical studies established that the conjugated survivin peptide mimic SurVaxM (SVN53-67/M57-KLH) could stimulate an anti-tumor immune response against murine glioma in vivo, as well as human glioma cells ex vivo. The current clinical study was conducted to test safety, immunogenicity and clinical effects of the vaccine. Recurrent malignant glioma patients whose tumors were survivin-positive, and who had either HLA-A*02 or HLA-A*03 MHC class I allele-positivity, were given subcutaneous injections of SurVaxM (500 μg) in Montanide ISA 51 with sargramostim (100 μg) at 2-week intervals. SurVaxM was well tolerated with mostly grade one adverse events (AE) and no serious adverse events (SAE) attributable to the study drug. Six patients experienced local injection site reactions; three patients reported fatigue (grades 1 and 2), and 2 patients experienced myalgia (grade 1). Six of eight immunologically evaluable patients developed both cellular and humoral immune responses to vaccine. The vaccine also stimulated HLA-A*02, HLA-A*03 and HLA-A*24 restricted T cell responses. Three patients maintained a partial clinical response or stable disease for more than 6 months. Median progression-free survival was 17.6 weeks, and median overall survival was 86.6 weeks from study entry with seven of nine patients surviving more than 12 months.

Keywords: Apoptosis; Glioma; Immunotherapy; Peptide; Survivin; Vaccine.

Conflict of interest statement

R.A. Fenstermaker and M.J. Ciesielski are co-inventors on patents regarding SVN53-67/M57-KLH and are co-founders of MimiVax, LLC, which has licensed such patents from Roswell Park Cancer Institute. No additional potential conflicts of interest were disclosed by the other authors.

Figures

Fig. 1

Long survivin peptide contained in SVN53-67/M57-KLH is shown with brackets indicating empirically confirmed immuno-reactive HLA-A*02, HLA-A*03, HLA-A*11 and HLA-A*24 epitopes within it. The position of the cysteine-to-methionine substitution (mimic) within the peptide is indicated (dark gray)

Fig. 2

a FACS analysis of representative MHC class I dextramer assays of PBMC from a HLA-A*02/24 patient. Multimer binding of CD8+ T cells specific for survivin epitopes Pep1 and Pep6 (see Fig. 1) is shown. The upper right quadrant of each panel shows survivin multimer +/CD8+ gated T cells. Week 0 is pre-immunization blood sampling. Control represents results with a nonsense dextramer. b Binding of multimers to CD8+ T cell receptors in patients measured at weeks 8–150 following study entry. Data acquisition was performed by FACS analysis as revealed in a. Patient samples registering ≥1 % over baseline survivin-specific CD8+ T cells are shown as (filled circle). Patients not mounting an immune response to a particular peptide are shown as (open circle). Weakly positive patients registering ≥0.75 % and <1 % above baseline are (circled times). Custom-designed multimers included: Pep1, HLA-A*0201: QMFFCFKEL; Pep2, HLA-A*0201: AQMFFCFKEL; Pep3, HLA-A*0301: DLAQMFFCFK; Pep4, HLA-A*0301: LAQMFFCFK; Pep5, HLA-A*0301: AQMFFCFK; and Pep6; HLA-A*24: DLAQMFFCF. A negative control nonsense multimer was used to assess nonspecific binding. MHC Dextramer-PE (Immudex, Copenhagen, Denmark) to A*0201:QMFFCFKEL; A*0301:AQMFFCFK; A*0301:DLAQMFFCFK; A*0301:LAQMFFCFK; as well as iTag-PE Tetramer (BD Coulter) to A*0201:AQMFFCFKEL; and A*24:DLAQMFFCF

Fig. 3

Antibodies produced in response to vaccination were measured as a potential biomarker. a IgG antibodies to SVN53-67/M57, and b IgG antibodies to SVN53-67 were measured in the serum of each patient by ELISA following prime-boost doses, and in those patients who entered an extended dosing phase. Seven patients produced significant levels (>1 O.D.) of SVN53-67/M57 (a) and six patients developed high titers (>1 O.D.) of SVN53-67 antibodies (b). One patient (#4) was not evaluable due to progression before all four prime-boost doses could be administered. c IFNγ mRNA levels in isolated CD4+ (left) and CD8+ (right) cells from individual vaccinated patients. Cells were stimulated in culture for 2 h with pooled overlapping survivin peptides (a.a. 53–67) at the indicated concentrations. qPCR of IFNγ mRNA was performed as described. Relative quantitation was performed using the ∆∆Ct method, and data were standardized to GAPDH mRNA expression and normalized to IFNγ mRNA levels in unstimulated cells. CD4+ and CD8+ cell populations were verified to be 94 and 98 % pure, respectively, by FACS analysis (data not shown)

Fig. 4

FACS analysis of CD8+ and CD4+ proliferation in CFSE dye-loaded PBMC obtained from two patients (patient #1; a–d) and (patient #7; e–h) 12 weeks following vaccination. Proliferation was measured in response to stimulation of cells using either the long (15 amino acid) survivin peptide mimic (SVN53-67/M57) or a 14 amino acid unrelated control peptide (seq: LEEKKQNYVVTDHC). Cell division is indicated by left-shifted peaks

Fig. 5

Immunohistochemistry of T and B cell markers (×200) in tissue sections of one patient (#8) with recurrent disease 5.6 months following protocol entry. a CD4+ and b CD8+ T cells are shown in representative fields of the patient’s glioblastoma prior to vaccine treatment. c CD4+, d CD8+, e CD20+ and f PD-L1+ cells within contiguous histologic sections of tumor after vaccine treatment and subsequent tumor recurrence

Fig. 6

Progression-free survival (filled triangle) and overall survival (filled square) of patients. Median PFS was 17.6 weeks, and median OS was 86.6 weeks following study entry. MRI showing tumor at diagnosis (left), first recurrence (center) and 42-month follow-up (right)