Clinical Activity of an hTERT-Specific Cancer Vaccine (Vx-001) in "Immune Desert" NSCLC.

BACKGROUND: Tumors can be separated into immunogenic/hot and non-immunogenic/cold on the basis of the presence of tumor-infiltrating lymphocytes (TILs), the expression of PD-L1 and the tumor mutation burden (TMB). In immunogenic tumors, TILs become unable to control tumor growth because their activity is suppressed by different inhibitory pathways, including PD-1/PD-L1. We hypothesized that tumor vaccines may not be active in the immunosuppressive microenvironment of immunogenic/hot tumors while they could be efficient in the immune naïve microenvironment of non-immunogenic/cold tumors. METHODS: The randomized phase II Vx-001-201 study investigated the effect of the Vx-001 vaccine as maintenance treatment in metastatic non-small cell lung cancer (NSCLC) patients. Biopsies from 131 (68 placebo and 63 Vx-001) patients were retrospectively analyzed for PD-L1 expression and TIL infiltration. TILs were measured as tumor-associated immune cells (TAICs), CD3-TILs, CD8-TILs and granzyme B-producing TILs (GZMB-TILs). Patients were distinguished into PD-L1(+) and PD-L1(-) and into TIL high and TIL low. FINDINGS: There was no correlation between PD-L1 expression and Vx-001 clinical activity. In contrast, Vx-001 showed a significant improvement of overall survival (OS) vs. placebo in TAIC low (21 vs. 8.1 months, p = 0.003, HR = 0.404, 95% CI 0.219-0.745), CD3-TIL low (21.6 vs. 6.6 months, p < 0.001, HR = 0.279, 95% CI 0.131-0.595), CD8-TIL low (21 vs. 6.6 months, p < 0.001; HR = 0.240, 95% CI 0.11-0.522) and GZMB-TIL low (20.7 vs. 11.1 months, p = 0.011, HR = 0.490, 95% CI 0.278-0.863). Vx-001 did not offer any clinical benefit in patients with TAIC high, CD3-TIL high, CD8-TIL high or GZMB-TIL high tumors. CD3-TIL, CD8-TIL and GZMB-TIL were independent predictive factors of Vx-001 efficacy. CONCLUSIONS: These results support the hypothesis that Vx-001 may be efficient in patients with non-immunogenic/cold but not with immunogenic/hot tumors.

Optimized tumor cryptic peptides: the basis for universal neo-antigen-like tumor vaccines.

The very impressive clinical results recently obtained in cancer patients treated with immune response checkpoint inhibitors boosted the interest in immunotherapy as a therapeutic choice in cancer treatment. However, these inhibitors require a pre-existing tumor specific immune response and the presence of tumor infiltrating T cells to be efficient. This immune response can be triggered by cancer vaccines. One of the main issues in tumor vaccination is the choice of the right antigen to target. All vaccines tested to date targeted tumor associated antigens (TAA) that are self-antigens and failed to show a clinical efficacy because of the immune self-tolerance to TAA. A new class of tumor antigens has recently been described, the neo-antigens that are created by point mutations of tumor expressing proteins and are recognized by the immune system as non-self. Neo-antigens exhibit two main properties: they are not involved in the immune self-tolerance process and are immunogenic. However, the majority of the neo-antigens are patient specific and their use as cancer vaccines requires their previous identification in each patient individualy that can be done only in highly specialized research centers. It is therefore evident that neo-antigens cannot be used for patient vaccination worldwide. This raises the question of whether we can find neo-antigen like vaccines, which would not be patient specific. In this review we show that optimized cryptic peptides from TAA are neo-antigen like peptides. Optimized cryptic peptides are recognized by the immune system as non-self because they target self-cryptic peptides that escape self-tolerance; in addition they are strongly immunogenic because their sequence is modified in order to enhance their affinity for the HLA molecule. The first vaccine based on the optimized cryptic peptide approach, Vx-001, which targets the widely expressed tumor antigen telomerase reverse transcriptase (TERT), has completed a large phase I clinical study and is currently being tested in a randomized phase II trial in non-small cell lung cancer (NSCLC) patients.

A general strategy to optimize immunogenicity of HLA-B*0702 restricted cryptic peptides from tumor associated antigens: Design of universal neo-antigen like tumor vaccines for HLA-B*0702 positive patients.

Tumor Associated Antigens (TAAs) are the privileged targets of almost all the cancer vaccines tested to date. Unfortunately all these vaccines failed to show a clinical efficacy. The main reason for this failure is the immune tolerance to TAAs that are self-proteins expressed by normal and cancer cells. Self-tolerance to TAAs is directed against their dominant rather than against their cryptic epitopes. The best way to overcome self-tolerance to TAAs would therefore be to target their cryptic epitopes. However, because of their low HLA-I affinity, cryptic peptides are non-immunogenic and cannot be used to stimulate an antitumor immune response unless their immunogenicity has been previously enhanced. In this paper we describe a general approach to enhance immunogenicity of almost all the HLA-B*0702 restricted cryptic peptides derived from TAAs. It consists in substituting residues at position 1 or 9 of low HLA-B*0702 affinity cryptic peptides by an Alanine or a Leucine respectively. These substitutions increase affinity of peptides for HLA-B*0702. These optimized cryptic peptides are strongly immunogenic and very importantly CTL they stimulate recognize their native counterparts.TAAs derived optimized cryptic peptides can be considered as universal antitumor vaccine since they escape self-tolerance, are immunogenic and are not patient specific.

A multicenter randomized phase IIb efficacy study of Vx-001, a peptide-based cancer vaccine as maintenance treatment in advanced non-small-cell lung cancer: treatment rationale and protocol dynamics.

We present the treatment rationale and study design of a multicenter, open-label, randomized, 2-arm, phase IIb study. Patients with stage IV or recurrent stage I to III non-small-cell lung cancer (NSCLC) whose disease does not progress after 4 cycles of first-line platinum-based chemotherapy will be randomized in a 1:1 ratio to 1 of 2 study arms. Patients will receive the cancer vaccine Vx-001 + Montanide ISA51 VG (Seppic, Paris, France) adjuvant subcutaneously, at a dose of 2 mg, or placebo + Montanide ISA51 VG adjuvant subcutaneously. The vaccination protocol comprises 2 injections with the TYR-Vx001 or placebo (1 at day 0 and another at week 3) and 4 injections with the ARG-Vx001 or placebo, at weeks 6, 9, 12, and 15. After the treatment assessment at week 18, patients will receive the ARG-Vx001 or placebo every 12 weeks starting from week 27 until disease progression, unacceptable toxicity, withdrawal of informed consent, or death. The primary end point of this study is the survival rate at 12 months. Secondary end points include time-to-event comparison of overall survival and comparison of time to treatment failure. Exploratory objectives include comparison of disease control rate after the end of subsequent second-line treatments, comparisons of vaccine immune responses, comparison of survival rate at 12 months in patients with vaccine-induced immune response detected after the second and sixth injections, identification of biomarkers on lymphocytes and on tumors, and comparison of safety and tolerability.

Immunological responses in cancer patients after vaccination with the therapeutic telomerase-specific vaccine Vx-001.

Vx-001, an HLA-A*0201 restricted telomerase (TERT)-specific anti-tumor vaccine, is composed of the 9-mer cryptic TERT(572) peptide and its optimized variant TERT(572Y). We have previously shown that Vx-001 is non-toxic, highly immunogenic and in vaccinated NSCLC patients early specific immune response is associated with prolonged survival. The aim of the present study was to investigate the specific T-cell immune response against Vx-001. Fifty-five patients with chemo-resistant advanced solid tumors were vaccinated with TERT(572Y) (2 subcutaneous injections) followed by TERT(572) peptide (4 subcutaneous injections) every 3 weeks. Specific immune response was evaluated by IFN-γ and perforin ELISpot and intracellular cytokine staining assays. TERT-reactive T cells were detected in 27 (51%) out of 53 evaluable patients after the 2nd vaccination and in 22 (69%) out of 32 evaluable patients after the completion of 6 vaccinations. Immune responses developed irrespective of the stage of disease and disease status before vaccination. Patients with disease progression at study entry who developed a post-vaccination-induced immunological response had a significant overall survival benefit compared to the post-vaccination non-responders. The Vx-001 vaccine is a promising candidate for cancer immunotherapy since it can induce a TERT-specific T-cell immune response that is associated with prolonged survival.

Development of optimized cryptic peptides for immunotherapy.

Specific immunotherapy is based on the use of tumor-specific antigens to induce an efficient antitumor immune response. Although tumors are known to be weakly immunogenic and therefore capable of escaping immune surveillance, the objective of tumor vaccination is to induce a frequent, strong and long-lasting antitumor immune response based mainly on the activation of cytotoxic T-lymphocytes. However, as widely expressed tumor antigens (universal tumor antigens) often correspond to normal proteins expressed not only by tumor cells but also by normal cells and tissues, these antigens are generally tolerated by the immune system. Thus, circumventing self tolerance to universal tumor antigens is a major goal of cancer vaccine research. Disappointing results obtained to date with most tumor vaccines has led to a shift in research toward determining ways of stimulating the immune response through the use of new adjuvants, immunostimulants and delivery vectors. However, although these aspects are clearly crucial to vaccine development, breakthroughs in the field may lie in the use of strong antigens as optimized cryptic peptides derived from universal tumor antigens, combined with a potent adjuvant. Targeting cryptic tumor peptides/antigens is an efficient way of overcoming tolerance. Indeed, the first vaccine based on an optimized cryptic peptide induced strong antitumor immunity and demonstrated promising clinical activity.

CpG oligodeoxynucleotides activate dendritic cells in vivo and induce a functional and protective vaccine immunity against a TERT derived modified cryptic MHC class I-restricted epitope.

The use of synthetic peptides derived from tumor-associated Ags is attractive for the development of antitumoral vaccines as far as strong adjuvants are found to render them immunogenic. Here, we investigated the possibility to enhance the CD8 response against the human and mouse shared TERT(572Y) HLA-A*0201 restricted modified cryptic peptide by using ODN-CpG as adjuvant. Humanized transgenic mice were immunized with the TERT(572Y) modified cryptic peptide in the presence of ODN-CpG and compared to mice immunized in IFA. By contrast with IFA, we first showed that, in vivo, ODN-CpG leads to the recruitment of dendritic cells in the lymph nodes draining the injection site. Those cells and especially the CD11c+ CD11b- CD8a+ lymphoid and the CD11c+ B220+ plasmacytoid dendritic cells were activated as shown by up-regulation of CD40 at their cell surface. Immunization against TERT(572Y) peptide in the presence of ODN-CpG rather than IFA led to a strong CD8 response and can delayed mortality in an induced tumor model. Study of the CD8 response obtained after antigenic challenge suggested that a functional memory response is induced upon vaccination with ODN-CpG. Thus, MHC class I-restricted epitope in combination of ODN-CpG is a promising and rather simple cancer vaccine formulation.