A melanoma helper peptide vaccine increases Th1 cytokine production by leukocytes in peripheral blood and immunized lymph nodes

Multipeptide vaccines for melanoma in the adjuvant setting: long-term survival outcomes and post-hoc analysis of a randomized phase II trial

The critical roles of CD4+ T cells have been understudied for cancer vaccines. Here we report long-term clinical outcomes of a randomized multicenter phase II clinical trial (NCT00118274), where patients with high-risk melanoma received a multipeptide vaccine targeting CD8+ T cells (12MP) and were randomized to receive either of two vaccines for CD4+ (helper) T cells: 6MHP (6 melanoma-specific helper peptides), or tet (a nonspecific helper peptide from tetanus toxoid). Cyclophosphamide (Cy) pre-treatment was also assessed. Primary outcomes for T cell responses to 12MP, 6MHP, and tet were previously reported, suggesting immunogenicity of both vaccines but that CD8 T cell responses to 12MP were lower when tet was replaced with 6MHP. Here, in post-hoc analyses, we report durable prolongation of overall survival by adding 6MHP instead of tet. That benefit was experienced only by male patients. A favorable interaction of 6MHP and Cy is also suggested. Multivariable Cox regression analysis of the intent-to-treat population identify vaccine arm (12MP + 6MHP+Cy) and patient sex (male) as the two significant predictors of enhanced survival. These findings support the value of adding cognate T cell help to cancer vaccines and also suggest a need to assess the impact of patient sex on immune therapy outcomes.

Phase I/II clinical trial of a helper peptide vaccine plus PD-1 blockade in PD-1 antibody-naïve and PD-1 antibody-experienced patients with melanoma (MEL64)

BACKGROUND

A vaccine containing 6 melanoma-associated peptides to stimulate helper T cells (6MHP) is safe, immunogenic, and clinically active. A phase I/II trial was designed to evaluate safety and immunogenicity of 6MHP vaccines plus programmed death 1 (PD-1) blockade.

PARTICIPANTS AND METHODS

Participants with advanced melanoma received 6MHP vaccines in an incomplete Freund's adjuvant (6 vaccines over 12 weeks). Pembrolizumab was administered intravenously every 3 weeks. Tumor biopsies at baseline and day 22 were analyzed by multiplex immunohistochemistry. Primary end points were safety (Common Terminology Criteria for Adverse Events V.4.03) and immunogenicity (ex vivo interferon-γ ELISpot assay). Additional end points included changes in the tumor microenvironment (TME) and clinical outcomes.

RESULTS

Twenty-two eligible participants were treated: 6 naïve to PD-1 antibody (Ab) and 16 PD-1 Ab-experienced. Median follow-up was 24.4 months. Most common treatment-related adverse events (any grade) included injection site reactions, fatigue, anemia, lymphopenia, fever, elevated aspartate aminotransferase, pruritus, and rash. Treatment-related dose-limiting toxicities were observed in 3 (14%) participants, which did not cross the study safety bound. A high durable T cell response (Rsp) to 6MHP was detected in only one participant, but twofold T cell Rsps to 6MHP were detected in 7/22 (32%; 90% CI (16% to 52%)) by week 13. Objective clinical responses were observed in 23% (1 complete response, 4 partial responses), including 4/6 PD-1 Ab-naïve (67%) and 1/16 PD-1 Ab-experienced (6%). Overall survival (OS) was longer for PD-1 Ab-naïve than Ab-experienced participants (HR 6.3 (90% CI (2.1 to 28.7)). In landmark analyses at 13 weeks, OS was also longer for those with T cell Rsps (HR 6.5 (90% CI (2.1 to 29.2)) and for those with objective clinical responses. TME evaluation revealed increased densities of CD8+ T cells, CD20+ B cells, and Tbet+ cells by day 22.

CONCLUSIONS

Treatment with the 6MHP vaccine plus pembrolizumab was safe, increased intratumoral lymphocytes, and induced T cell Rsps associated with prolonged OS. The low T cell Rsp rate in PD-1 Ab-experienced participants corroborates prior murine studies that caution against delaying cancer vaccines until after PD-1 blockade. The promising objective response rate and OS in PD-1 Ab-naïve participants support consideration of a larger study in that setting.

CD40 and CD80/86 signaling in cDC1s mediate effective neoantigen vaccination and generation of antigen-specific CX3CR1+ CD8+ T cells

The use of tumor mutation-derived neoantigen represents a promising approach for cancer vaccines. Preclinical and early phase human clinical studies have shown the successful induction of tumor neoepitope-directed responses; however, overall clinical efficacy of neoantigen vaccines has been limited. One major obstacle of this strategy is the prevailing lack of sufficient understanding of the mechanism underlying the generation of neoantigen-specific CD8⁺ T cells. Here, we report a correlation between antitumor efficacy of neoantigen/toll-like receptor 3 (TLR3)/CD40 agonists vaccination and an increased frequency of circulating antigen-specific CD8⁺ T cells expressing CX3C chemokine receptor 1 (CX3CR1) in a preclinical model. Mechanistic studies using mixed bone marrow chimeras identified that CD40 and CD80/86, but not CD70 signaling in Batf3-dependent conventional type 1 dendritic cells (cDC1s) is required for the antitumor efficacy of neoantigen vaccine and generation of neoantigen-specific CX3CR1⁺ CD8⁺ T cells. Although CX3CR1⁺ CD8⁺ T cells exhibited robust in vitro effector function, in vivo depletion of this subset did not alter the antitumor efficacy of neoantigen/TLR3/CD40 agonists vaccination. These findings indicate that the vaccine-primed CX3CR1⁺ subset is dispensable for antitumor CD8⁺ T cell responses, but can be used as a blood-based T-cell biomarker for effective priming of CD8⁺ T cells as post-differentiated T cells. Taken together, our results reveal a critical role of CD40 and CD80/86 signaling in cDC1s in antitumor efficacy of neoantigen-based therapeutic vaccines, and implicate the potential utility of CX3CR1 as a circulating predictive T-cell biomarker in vaccine therapy.

LDH-A negatively regulates dMMR in colorectal cancer

Although immune checkpoint inhibitors (ICIs) have achieved unprecedented success in dMMR tumors, pMMR tumors accounting for 85% of colorectal cancer (CRC) cases remain unresponsive. Lactate dehydrogenase A (LDH-A) is the rate-limiting enzyme that catalyzes the transformation of pyruvate to lactate in the process of glycolysis. We investigated the relationship between LDH-A and dMMR with the purpose of exploring the treatment strategy for pMMR CRC patients. We here show that LDH-A can promote the proliferation of dMMR and pMMR CRC cells by positively regulating MMR proteins both in vitro and in vivo. LDH-A inhibition can improve the efficacy of PD-1 blockade in a pMMR CRC xenograft model. A statistical analysis of 186 CRC specimens showed a significant correlation between LDH-A and dMMR status. Moreover, patients with both low LDH-A expression and dMMR exhibited better disease-free survival compared with patients with other combinations. The close correlation of LDH-A and dMMR may offer a promising therapeutic strategy in which the combination of LDH-A inhibitor and ICIs may improve the clinical benefit for pMMR CRC patients.

Trial to evaluate the immunogenicity and safety of a melanoma helper peptide vaccine plus incomplete Freund's adjuvant, cyclophosphamide, and polyICLC (Mel63)

Background

Peptide vaccines designed to stimulate melanoma-reactive CD4⁺ T cells can induce T cell and antibody (Ab) responses, associated with enhanced overall survival. We hypothesized that adding toll-like receptor 3 agonist polyICLC to an incomplete Freund’s adjuvant (IFA) would be safe and would support strong, durable CD4⁺ T cell and Ab responses. We also hypothesized that oral low-dose metronomic cyclophosphamide (mCy) would be safe, would reduce circulating regulatory T cells (T-regs) and would further enhance immunogenicity.

Participants and methods

An adaptive design based on toxicity and durable CD4+ T cell immune response (dRsp) was used to assign participants with resected stage IIA-IV melanoma to one of four study regimens. The regimens included a vaccine comprising six melanoma peptides restricted by Class II MHC (6MHP) in an emulsion with IFA alone (Arm A), with IFA plus systemic mCy (Arm B), with IFA+ local polyICLC (Arm C), or with IFA+ polyICLC+ mCy (Arm D). Toxicities were recorded (CTCAE V.4.03). T cell responses were measured by interferon γ ELIspot assay ex vivo. Serum Ab responses to 6MHP were measured by ELISA. Circulating T-regs were assessed by flow cytometry.

Results

Forty-eight eligible participants were enrolled and treated. Early data on safety and dRsp favored enrollment on arm D. Total enrollment on Arms A-D were 3, 7, 6, and 32, respectively. Treatment-related dose-limiting toxicities (DLTs) were observed in 1/7 (14%) participants on arm B and 2/32 (6%) on arm D. None exceeded the 25% DLT threshold for early closure to enrollment for any arm. Strong durable T cell responses to 6MHP were detected ex vivo in 0%, 29%, 67%, and 47% of participants on arms A-D, respectively. IgG Ab responses were greatest for arms C and D. Circulating T-regs frequencies were not altered by mCy.

Conclusions

6MHP vaccines administered with IFA, polyICLC, and mCy were well tolerated. The dRsp rate for arm D of 47% (90% CI 32 to 63) exceeded the 18% (90% CI 11 to 26) rate previously observed with 6MHP in IFA alone. Vaccination with IFA+ polyICLC (arm C) also showed promise for enhancing T cell and Ab responses.

Efficacy of Acupuncture and Moxibustion as a Subsequent Treatment after Second-Line Chemotherapy in Advanced Gastric Cancer

Objective

To explore whether acupuncture and moxibustion can prevent disease progression of advanced gastric cancer patients completing second-line chemotherapy and, if so, the related mechanism.

Method

Progression-free survival (PFS) and overall survival (OS) were main outcome measures. The real-time quantitative PCR was used to detect the expression of genes including T-bet, IFN-γ, GATA3, and IL-4 in peripheral blood mononuclear cells (PBMCs). IL-4, IL-6, Ca199, CRP, and IFN-γ in plasma levels were checked.

Results

170 patients were randomly assigned in a 3 : 2 ratio to receive either acupuncture and moxibustion or sham acupuncture until progression. 135 patients were included in the primary analysis. Both PFS and OS in treatment group were proven to be better than control group. Acupuncture and moxibustion promoted typical Th1 cells drifting, as confirmed by increased T-bet/IFN-γ and decreased GATA3/IL-4 in mRNA levels from PBMCs, as well as upregulating IFN-γ and downregulating IL-4 in plasma levels. IL-6, Ca199, and CRP in plasma levels were also reduced by acupuncture and moxibustion.

Conclusions

Acupuncture and moxibustion can prolong PFS and OS of advanced gastric cancer patients completing second-line chemotherapy by reversing Th1/Th2 shift and attenuating inflammatory responses.

Low-dose influenza vaccine Grippol Quadrivalent with adjuvant Polyoxidonium induces a T helper-2 mediated humoral immune response and increases NK cell activity

The influenza vaccine Grippol® Quadrivalent (GQ) is a new vaccine, containing the adjuvant Polyoxidonium® and recombinant hemagglutinins from 4 strains of the influenza virus in amount of 5-6 μg of each hemagglutinin per human dose. These doses of antigens are about 3 times less than the standard dose recommended by WHO. We sought to characterize the immune response to the GQ vaccine and to determine the contribution of the adjuvant in this response. BALB/c mice were vaccinated with GQ or with adjuvant-free antigen mixtures (AGs). Then, the antibody response, the number of memory T cells in the spleen, and the functional properties of splenocytes were determined. The vaccine GQ has been shown to induce antibodies to all 4 influenza hemagglutinins. The vaccination with GQ caused a strong increase in the AG-induced proliferation and production of Th2 cytokines ex vivo. These effects were equal to effect achieved by standard dose of antigens. Vaccination also caused the accumulation of CD4⁺ large lymphocytes with the phenotype of central and effector memory T cells in the spleen. The GQ vaccine enhanced the cytolytic activity of natural killer (NK) cells, whereas the adjuvant-free mixture of AGs in lowered and standard doses did not affect NK activity. We did not find a noticeable response of Th1 and CD8⁺ T cells to vaccination. In vitro, the GQ vaccine stimulated the maturation of human monocyte-derived dendritic cells (DCs) enhancing the expression of HLA-DR, CD80, CD83, CD86 and ICOSL molecules. Polyoxidonium without AGs also induced expression of ICOSL, which plays an important role in T-dependent humoral immune response. In summary, the low-dose influenza vaccine GQ with Polyoxidonium adjuvant is immunogenic, induces a Th2-polarized T-cell response and CD4⁺ memory T cells maturation, activates the production of antibodies to influenza hemagglutinins, and increases the activity of NK cells.

Updates in adjuvant systemic therapy for melanoma

There has been a rapid increase in adjuvant therapies approved for treatment following surgical resection of stages III/IV melanoma. We review current indications for adjuvant therapy, which currently includes a heterogenous group of stages III and IV patients with melanoma. We describe several pivotal clinical trials of systemic immune therapies, targeted immune therapies, and adjuvant vaccine strategies. Finally, we discuss the evidence for selecting the most appropriate treatment regimen(s) for the individual patient.

Immunotherapy of cancers comes of age

INTRODUCTION

Cancer immunotherapy has evolved and is aimed at generating the efficacious therapeutic modality to enhance the specificity and power of the immune system to combat tumors. Areas covered: Current efforts in cancer immunotherapy fall into three main approaches. One approach is through the blockade of immune checkpoints, another approach is through adoptive cellular therapy, and the last approach is through vaccination. The goal of this review is to summarize the current understanding and status of cancer immunotherapy in these three categories. Expert commentary: We foresee the development of therapeutic protocols combining these approaches with each other or conventional therapies to achieve the most appropriate guideline for management of cancer.

Immunoprevention of KRAS-driven lung adenocarcinoma by a multipeptide vaccine

Lung cancer remains the leading cause of cancer death worldwide. Mutations in KRAS are detected in up to 30% of lung cancer cases. No effective therapies specifically targeting mutant KRAS have been developed. Vaccination against KRAS mutants is one of the venues of active exploration. The present study evaluated both immunogenicity and antitumor efficacy of a newly formulated multipeptide vaccine targeting multiple epitopes of the KRAS molecule. The formulated vaccine contained top four peptides, which elicited the strongest immunologic response and showed 100% sequence homology between human and mouse. The multipeptide KRAS vaccine was tested in an inducible CCSP-TetO-KRAS^G12D mouse model, where the vaccine was administered prior to activating the mutant KRAS protein. The KRAS peptide vaccine exhibited striking efficacy, reducing tumor number and tumor burden by >80% when compared with adjuvant alone. Splenocytes collected from vaccinated animals showed a robust immunologic response to the immunizing peptides. Furthermore, in vitro stimulation of these splenocytes by the vaccinated peptides resulted in the secretion of cytokines indicative of Th1 responses but with minimal secretion of Th2-related cytokines. The multipeptide KRAS vaccine was immunogenic and efficacious in the primary prevention of KRAS-induced lung cancer, indicating that the approach potentially can be used to prevent other KRAS-driven cancers, either alone or in combination with other modalities.

Vaccines targeting helper T cells for cancer immunotherapy

There are compelling arguments for designing cancer vaccines specifically to induce CD4+ helper T cell responses. Recent studies highlight the crucial role of proliferating, activated effector memory Th1 CD4+ T cells in effective antitumor immunity and reveal that CD4+ T cells induce more durable immune-mediated tumor control than CD8+ T cells. CD4+ T cells promote antitumor immunity by numerous mechanisms including enhancing antigen presentation, co-stimulation, T cell homing, T cell activation, and effector function. These effects are mediated at sites of T cell priming and at the tumor microenvironment. Several cancer vaccine approaches induce durable CD4+ T cell responses and have promising clinical activity. Future work should further optimize vaccine adjuvants and combination therapies incorporating helper peptide vaccines.

Combination strategies to enhance the potency of monocyte-derived dendritic cell-based cancer vaccines

Dendritic cells (DCs) are potent inducers of adaptive immunity and their clinical use in cancer vaccine formulations remains an area of active translational and clinical investigation. Although cancer vaccines applied as monotherapies have had a modest history of clinical success, there is great enthusiasm for novel therapeutic strategies combining DC-based cancer vaccines with agents that 'normalize' immune function in the tumor microenvironment (TME). Broadly, these combination vaccines are designed to antagonize/remove immunosuppressive networks within the TME that serve to limit the antitumor action of vaccine-induced T cells and/or to condition the TME to facilitate the recruitment and optimal function and durability of vaccine-induced T cells. Such combination regimens are expected to dramatically enhance the clinical potency of DC-based cancer vaccine platforms.

PD-L1, PD-L2 and PD-1 expression in metastatic melanoma: Correlation with tumor-infiltrating immune cells and clinical outcome

Therapeutic blockade of PD-1/PD-L1 can have dramatic therapeutic benefit in some patients; however, the prognostic associations of PD-1 and its ligands, in the absence of therapeutic blockade have not been definitively addressed. In particular, associations of PD-L2 with immune infiltrates and with outcome have yet to be explored. We hypothesized that surface expression of both PD-L1 and PD-L2 by melanoma cells would be associated with immune cell infiltration and with overall patient survival, independent of checkpoint blockade therapy. We also characterized the heterogeneity of their distribution within a tumor and within tumors of the same patient. Tissue microarrays of metastatic melanoma samples from 147 patients were quantified for CD8⁺, CD45, CD4⁺, CD3, CD163, CD20, CD138, FoxP3, PD-1, PD-L1 and PD-L2 markers by immunohistochemistry. Relationships between the proportions of PD-L1 and PD-L2 expressing tumor cells with the immune cell count, distribution (immunotype) and patient survival were studied. Expressions of both PD-L1 and PD-L2 correlated significantly with increasing densities of immune cells in the tumor specimens and with immunotype. Positive PD-L2 expression was associated with improved overall survival and the simultaneous positive expression of both PD-1 ligands showed a higher association with survival. Significant heterogeneity of PD-L1 and PD-L2 expressions within tumors were observed, however, they were less pronounced with PD-L2. In conclusion, both are markers of immune infiltration and PD-L2, alone or in combination with PD-L1, is a marker for prognosis in metastatic melanoma patients. Larger tumor samples yield more reliable assessments of PD-L1/L2 expression.

A High RORγT/CD3 Ratio is a Strong Prognostic Factor for Postoperative Survival in Advanced Colorectal Cancer: Analysis of Helper T Cell Lymphocytes (Th1, Th2, Th17 and Regulatory T Cells)

BACKGROUND

Tumor-infiltrating lymphocytes (TILs), part of the host immune response, have been widely reported as influential factors in the tumor microenvironment for the clinical outcome of colorectal cancer (CRC). However, the network of helper T cells is very complex, and which T-cell subtypes affect the progression of CRC and postoperative prognosis remains unclear. This study investigated the expression of several subtypes of TILs including T helper type 1 (Th1), Th2, Th17, and regulatory T (Treg) cells to determine their correlation with clinicopathologic features and postoperative prognosis.

METHODS

The study investigated the expression of TILs using immunohistochemistry of tissue microarray samples for 199 CRC patients. The number of each T-cell subtype infiltrating tumors was counted using ImageJ software. The relationship between TIL marker expression, clinicopathologic features, and prognosis was analyzed.

RESULTS

A high RORγT/CD3 ratio (Th17 ratio) was significantly correlated with lymph node metastasis (p = 0.002), and a high of Foxp3/CD3 ratio (Treg ratio) was correlated with tumor location in the colon (p = 0.04), as shown by the Chi square test. In multivariate analysis, a high RORγT/CD3 ratio was the only independent prognostic factor for overall survival (p = 0.04; hazard ratio [HR], 1.84; 95% confidence interval [CI] 1.02-3.45).

CONCLUSIONS

This study confirmed a high RORγT/CD3 ratio as a strong prognostic marker for postoperative survival. The immunohistochemistry results suggest that Th17 may affect lymph node metastasis in CRC. If new immunotherapies reducing Th17 expression are established, they may improve the efficiency of cancer treatment and prolong the survival of patients with CRC.

Long-term outcomes of helper peptide vaccination for metastatic melanoma

OBJECTIVE

The objective of this study was to compare the long-term outcome of patients with metastatic melanoma vaccinated with 6MHP to that of a group of unvaccinated historical controls.

BACKGROUND

A multipeptide vaccine (6MHP), designed to induce helper T cells against melanocytic and cancer-testis antigens, has been shown to induce specific Th1-dominant CD4+ T cell responses.

METHODS

The 6MHP vaccine was administered to patients with metastatic melanoma. Circulating CD4+ T cell responses were measured by proliferation or direct IFN-gamma ELIspot assay. Overall survival of vaccinated patients was compared to a group of clinically comparable historical controls using multivariable Cox regression analysis and Kaplan-Meier survival analysis, taking into account age, metastatic site, and resection status.

RESULTS

Across 40 vaccinated patients and 87 controls, resection status (HR 0.54, P = 0.004) and vaccination (HR 0.24, P < 0.001) were associated with improved overall survival. Forty pairs of vaccinated patients and controls were matched by metastatic site, resection status, and age within 10 years. Median survival was significantly longer for vaccinated patients (5.4 vs 1.3 years, P < 0.001). Among the vaccinated patients, the development of a specific immune response after vaccination was associated with improved survival (HR 0.35, P = 0.040).

CONCLUSIONS

Helper peptide vaccination is associated with improved overall survival among patients with metastatic melanoma. These data support a randomized prospective trial of the 6MHP vaccine.

Vaccination with Melanoma Helper Peptides Induces Antibody Responses Associated with Improved Overall Survival

PURPOSE

A melanoma vaccine incorporating six peptides designed to induce helper T-cell responses to melanoma antigens has induced Th1-dominant CD4(+) T-cell responses in most patients, and induced durable clinical responses or stable disease in 24% of evaluable patients. The present study tested whether this vaccine also induced antibody (Ab) responses to each peptide, and whether Ab responses were associated with T-cell responses and with clinical outcome.

EXPERIMENTAL DESIGN

Serum samples were studied from 35 patients with stage III-IV melanomas vaccinated with 6 melanoma helper peptides (6MHP). IgG Ab responses were measured by ELISA. Associations with immune response and overall survival were assessed by log-rank test and χ(2) analysis of Kaplan-Meier data.

RESULTS

Ab responses to 6MHP were detected by week 7 in 77% of patients, and increased to peak 6 weeks after the last vaccine and persisted to 6 months. Ab responses were induced most frequently to longer peptides. Of those with T-cell responses, 82% had early Ab responses. Survival was improved for patients with early Ab response (P = 0.0011) or with early T-cell response (P < 0.006), and was best for those with both Ab and T-cell responses (P = 0.0002).

CONCLUSIONS

Vaccination with helper peptides induced both Ab responses and T-cell responses, associated with favorable clinical outcome. Such immune responses may predict favorable clinical outcome to guide combination immunotherapy. Further studies are warranted to understand mechanisms of interaction of these Abs, T-cell responses, and tumor control.

Vaccines, Adjuvants, and Dendritic Cell Activators--Current Status and Future Challenges

Cancer vaccines offer a low-toxicity approach to induce anticancer immune responses. They have shown promise for clinical benefit with one cancer vaccine approved in the United States for advanced prostate cancer. As other immune therapies are now clearly effective for treatment of advanced cancers of many histologies, there is renewed enthusiasm for optimizing cancer vaccines for use to prevent recurrence in early-stage cancers and/or to combine with other immune therapies for therapy of advanced cancers. Future advancements in vaccine therapy will involve the identification and selection of effective antigen formulations, optimization of adjuvants, dendritic cell (DC) activation, and combination therapies. In this summary we present the current practice, the broad collection of challenges, and the promising future directions of vaccine therapy for cancer.

Trial Watch: Peptide-based anticancer vaccines

Malignant cells express antigens that can be harnessed to elicit anticancer immune responses. One approach to achieve such goal consists in the administration of tumor-associated antigens (TAAs) or peptides thereof as recombinant proteins in the presence of adequate adjuvants. Throughout the past decade, peptide vaccines have been shown to mediate antineoplastic effects in various murine tumor models, especially when administered in the context of potent immunostimulatory regimens. In spite of multiple limitations, first of all the fact that anticancer vaccines are often employed as therapeutic (rather than prophylactic) agents, this immunotherapeutic paradigm has been intensively investigated in clinical scenarios, with promising results. Currently, both experimentalists and clinicians are focusing their efforts on the identification of so-called tumor rejection antigens, i.e., TAAs that can elicit an immune response leading to disease eradication, as well as to combinatorial immunostimulatory interventions with superior adjuvant activity in patients. Here, we summarize the latest advances in the development of peptide vaccines for cancer therapy.