Toshiaki Yoshikawa

Phase I Trial of a Glypican-3–Derived Peptide Vaccine for Advanced Hepatocellular Carcinoma: Immunologic Evidence and Potential for Improving Overall Survival

Purpose: The carcinoembryonic antigen glypican-3 (GPC3) is an ideal target of anticancer immunotherapy against hepatocellular carcinoma (HCC). In this nonrandomized, open-label, phase I clinical trial, we analyzed the safety and efficacy of GPC3 peptide vaccination in patients with advanced HCC. Experimental Design: Thirty-three patients with advanced HCC underwent GPC3 peptide vaccination (intradermal injections on days 1, 15, and 29 with dose escalation). The primary endpoint was the safety of GPC3 peptide vaccination. The secondary endpoints were immune response, as measured by IFN-γ ELISPOT assay, and the clinical outcomes tumor response, time to tumor progression, and overall survival (OS). Results: GPC3 vaccination was well-tolerated. One patient showed a partial response, and 19 patients showed stable disease 2 months after initiation of treatment. Four of the 19 patients with stable disease had tumor necrosis or regression that did not meet the criteria for a partial response. Levels of the tumor markers α-fetoprotein and/or des-γ-carboxy prothrombin temporarily decreased in nine patients. The GPC3 peptide vaccine induced a GPC3-specific CTL response in 30 patients. Furthermore, GPC3-specific CTL frequency after vaccination correlated with OS. OS was significantly longer in patients with high GPC3-specific CTL frequencies (N = 15) than in those with low frequencies (N = 18; P = 0.033). Conclusions: GPC3-derived peptide vaccination was well-tolerated, and measurable immune responses and antitumor efficacy were noted. This is the first study to show that peptide-specific CTL frequency can be a predictive marker of OS in patients with HCC receiving peptide vaccination. Clin Cancer Res; 18(13); 3686–96. ©2012 AACR.

HLA-A2-restricted glypican-3 peptide-specific CTL clones induced by peptide vaccine show high avidity and antigen-specific killing activity against tumor cells

Glypican‐3 (GPC3) is an onco‐fetal antigen that is overexpressed in human hepatocellular carcinoma (HCC), and is only expressed in the placenta and embryonic liver among normal tissues. Previously, we identified an HLA‐A2‐restricted GPC3144–152 (FVGEFFTDV) peptide that can induce GPC3‐reactive CTLs without inducing autoimmunity in HLA‐A2 transgenic mice. In this study, we carried out a phase I clinical trial of HLA‐A2‐restricted GPC3144–152 peptide vaccine in 14 patients with advanced HCC. Immunological responses were analyzed by ex vivoγ‐interferon enzyme‐linked immunospot assay. The frequency of GPC3144–152 peptide‐specific CTLs after vaccination (mean, 96; range, 5–441) was significantly larger than that before vaccination (mean, 6.5; range, 0–43) (P < 0.01). An increase in the GPC3144–152 peptide‐specific CTL frequency was observed in 12 (86%) of 14 patients after vaccination. Additionally, there was a significant correlation between the maximum value of GPC3144–152 peptide‐specific CTLs after vaccination and the dose of the peptide injected (P = 0.0166, r = 0.665). Moreover, we established several GPC3144–152 peptide‐specific CTL clones from PBMCs of patients vaccinated with GPC3144–152 peptide by single cell sorting using Dextramer and CD107a antibody. These CTL clones had high avidity (the recognition efficiency showing 50% cytotoxicity was 10−10 or 10−11 M) and could recognize HCC cell lines expressing GPC3 in an HLA‐class I‐restricted manner. These results suggest that GPC3144–152 peptide vaccine can induce high avidity CTLs capable of killing HCC cells expressing GPC3. This trial was registered with University Hospital Medical Information Network number 000001395. (Cancer Sci 2011; 102: 918–925)

Decreased NKG2D Expression on CD8+ T Cell Is Involved in Immune Evasion in Patients with Gastric Cancer

Purpose: Some studies suggest that the immunoreceptor NKG2D expression on CD8+ T cells is down-regulated and this reduction may be involved in immune evasion in cancer patients. The present study was designed to investigate NKG2D expression on CD8+ T lymphocytes and its relationship to immune evasion in gastric cancer patients. Experimental Design: NKG2D expression on both circulating and tumor-infiltrating CD8+ T cells was evaluated by multicolor flow cytometry. Soluble MHC class I chain-related gene A (MICA) in the sera was quantitated by ELISA. Transwell experiments were carried out to determine the effect of cancer cells on NKG2D expression. Results: NKG2D expression on circulating CD8+ T cells was down-regulated and significantly correlated with IFN-γ production in gastric cancer patients (r = 0.68; P = 0.007). NKG2D expression was closely related to undifferentiated cancer (P = 0.021) as was the depth of invasion (P = 0.012). There was no difference in soluble MICA between gastric cancer patients and normal controls. NKG2D expression on CD8+ T cells was remarkably reduced in the tissue of gastric cancer compared with peripheral blood (P = 0.046). Complete removal of tumor by surgery restored NKG2D expression on CD8+ T cells (P = 0.0049). Transwell experiments showed that this down-regulation was induced by direct contact between cancer cells and CD8+ T cells and that soluble factors did not affect the NKG2D expression. This phenomenon was blocked by the addition of anti-MICA antibodies. Conclusions: Decreased NKG2D expression may be one of the key mechanisms responsible for immune evasion by tumors in gastric cancer.

Radiofrequency ablation for hepatocellular carcinoma induces glypican-3 peptide-specific cytotoxic T lymphocytes

Glypican-3 (GPC3), a carcinoembryonic antigen, is an ideal target for anticancer immunotherapy against hepatocellular carcinoma (HCC). In this study, we attempted to compare the induction of the GPC3-specific T-cell-mediated immune response after locoregional therapies in HCC patients and tumor-bearing mice. Twenty-seven HCC patients treated with locoregional therapies, including radiofrequency ablation (RFA), surgical resection and transcatheter arterial chemo-embolization (TACE), were prospectively enrolled in this study. Additionally, we performed RFA experiments using a mouse model. GPC3-specific T-cell response was investigated pre-treatment and post-treatment by an interferon-γ enzyme-linked immunospot assay using peripheral blood mononuclear cells from HCC patients and lymph node cells from tumor-bearing mice. Circulating GPC3-specific cytotoxic T lymphocytes (CTLs) were increased in 5 of 9 patients after RFA and in 4 of 9 patients after TACE, but in only 1 of 9 patients after surgical resection. All 7 patients with GPC3-expressing HCCs exhibited an increase in GPC3-specific CTLs after RFA or TACE, whereas none of the 7 patients did after surgical resection. The number of increased GPC3-specific CTLs after RFA was significantly larger than that after surgical resection (P=0.023). Similarly, the frequency of GPC3-specific CTLs after RFA was significantly greater than that after surgical resection in the mouse model (P=0.049). We validated for the first time the stronger effect on the immune system brought by RFA compared with surgical resection for HCC patients and tumor-bearing mice. Combined treatment of RFA and immunotherapy is a reasonable strategy against HCC.

Phase II study of the GPC3-derived peptide vaccine as an adjuvant therapy for hepatocellular carcinoma patients

ABSTRACT The recurrence rates of Hepatocellular carcinoma (HCC) are high, necessitating novel and effective adjuvant therapies. Therefore, we conducted a phase II study of glypican-3 (GPC3) peptide vaccine as an adjuvant therapy for HCC patients. Forty-one patients with initial HCC who had undergone surgery or radiofrequency ablation (RFA) were analyzed in this phase II, open-label, single-arm trial. Ten vaccinations were performed for 1 y after curative treatment. We also investigated case-control subjects, where selected patients treated surgically during the same period were analyzed. The expression of GPC3 in the available primary tumors was determined by immunohistochemical analysis. Six patients received RFA therapy while 35 received surgery. The recurrence rate tended to be lower in the 35 patients treated with surgery plus vaccination compared to 33 patients who underwent surgery alone (28.6% vs. 54.3% and 39.4% vs. 54.5% at 1 and 2 y, respectively; p = 0.346, 0.983). Twenty-five patients treated with surgery and vaccination had GPC3-positive tumors; the recurrence rate in this group was significantly lower compared to that in 21 GPC3-positive patients who received surgery only (24% vs. 48% and 52.4% vs. 61.9% at 1 and 2 y, respectively; p = 0.047, 0.387). The GPC3 peptide vaccine improved the 1-y recurrence rate in patients with GPC3-positive tumors. This study demonstrated that GPC3 expression by the primary tumor may be used as a biomarker in a putative larger randomized clinical trial to determine the efficacy of the GPC3-derived peptide vaccine.

Remarkable tumor lysis in a hepatocellular carcinoma patient immediately following glypican-3-derived peptide vaccination An autopsy case

We recently reported the safety, immunological and clinical responses to a GPC3-derived peptide vaccine in a phase I clinical trial of patients with advanced hepatocellular carcinoma (HCC). We conducted a subsequent trial in advanced HCC to assess the histopathological findings before and after vaccination with the GPC3 peptide. Here, we present the clinical course and the pathological study including the autopsy of a patient with advanced HCC in the ongoing clinical trial. A 62-year old patient suffering from HCC refractory to sorafenib therapy received the GPC3 peptide vaccine. The patient had fever and remarkably impaired liver function twice after vaccination. Contrast-enhanced CT after the second vaccination showed multiple low-density areas in the liver tumor, indicating tumor necrosis. In contrast, the tumor thrombus in the right atrium increased. The patient discontinued protocol treatment due to disease progression and died 30 days after the second vaccination. An autopsy was performed to determine the main cause of death and to evaluate the antitumor effect of the vaccination. A histological examination showed central necrosis in most of the intrahepatic tumor. The main cause of death was circulatory failure due to tumor thrombus, which occupied most of the right atrium. An immunohistochemical analysis revealed infiltration of CD8-positive T cells in the residual carcinoma, but not within the cirrhotic area. Ex vivo IFN-γ enzyme-linked immunospot analysis revealed vaccine-induced immune-reactivity against the GPC3 peptide. A histopathological examination at the estimated time of a strong immunological response demonstrated a GPC3 peptide vaccination-induced cytotoxic T-lymphocyte response with an anti-tumor effect.

Peptide vaccines for hepatocellular carcinoma

Immunotherapy is a potentially attractive treatment option for patients with hepatocellular carcinoma (HCC). We have reported that glypican-3 (GPC3) is an ideal target for anticancer immunotherapy against HCC because its expression is specifically detected in > 80% of HCCs, even during the early stages. Further, increased GPC3 expression is correlated with a poor prognosis. Based on results obtained from a preclinical study using mice, we conducted a phase I clinical trial using a GPC3-derived peptide vaccine. Phase I results showed that the GPC3-derived peptide vaccine was well tolerated. Furthermore, this was the first study to show that the frequency of peptide-specific cytotoxic T lymphocytes was correlated with overall survival in patients with HCC receiving a peptide vaccine. Next, we conducted a phase II clinical trial using the GPC3-derived peptide vaccine in patients with HCC after surgery or radiofrequency ablation (adjuvant setting). We are currently evaluating a third trial involving liver biopsies removed from patients with advanced HCC before and after GPC3-derived peptide vaccination. We expect that the results of these trials will result in future drug development.

Intratumoral peptide injection enhances tumor cell antigenicity recognized by cytotoxic T lymphocytes: a potential option for improvement in antigen-specific cancer immunotherapy

Antigen-specific cancer immunotherapy is a promising strategy for improving cancer treatment. Recently, many tumor-associated antigens and their epitopes recognized by cytotoxic T lymphocytes (CTLs) have been identified. However, the density of endogenously presented antigen-derived peptides on tumor cells is generally sparse, resulting in the inability of antigen-specific CTLs to work effectively. We hypothesize that increasing the density of an antigen-derived peptide would enhance antigen-specific cancer immunotherapy. Here, we demonstrated that intratumoral peptide injection leads to additional peptide loading onto major histocompatibility complex class I molecules of tumor cells, enhancing tumor cell recognition by antigen-specific CTLs. In in vitro studies, human leukocyte antigen (HLA)-A*02:01-restricted glypican-3144–152 (FVGEFFTDV) and cytomegalovirus495–503 (NLVPMVATV) peptide-specific CTLs showed strong activity against all peptide-pulsed cell lines, regardless of whether the tumor cells expressed the antigen. In in vivo studies using immunodeficient mice, glypican-3144–152 and cytomegalovirus495–503 peptides injected into a solid mass were loaded onto HLA class I molecules of tumor cells. In a peptide vaccine model and an adoptive cell transfer model using C57BL/6 mice, intratumoral injection of ovalbumin257–264 peptide (SIINFEKL) was effective for tumor growth inhibition and survival against ovalbumin-negative tumors without adverse reactions. Moreover, we demonstrated an antigen-spreading effect that occurred after intratumoral peptide injection. Intratumoral peptide injection enhances tumor cell antigenicity and may be a useful option for improvement in antigen-specific cancer immunotherapy against solid tumors.

Glypican‐3 could be an effective target for immunotherapy combined with chemotherapy against ovarian clear cell carcinoma

Glypican‐3 (GPC3) is useful not only as a novel tumor marker, but also as an oncofetal antigen for immunotherapy. We recently established HLA‐A2‐restricted GPC3144‐152 peptide‐specific CTL clones from hepatocellular carcinoma patients after GPC3144‐152 peptide vaccination. The present study was designed to evaluate the tumor reactivity of a HLA‐A2‐restricted GPC3144‐152 peptide‐specific CTL clone against ovarian clear cell carcinoma (CCC) cell lines. The GPC3144‐152 peptide‐specific CTL clone could recognize HLA‐A2‐positive and GPC3‐positive ovarian CCC cell lines on interferon (IFN)‐γ enzyme‐linked immunospot assay and showed cytotoxicity against KOC‐7c cells. The CTL clone recognized naturally processed GPC3‐derived peptide on ovarian CCC cells in a HLA class I‐restricted manner. Moreover, we confirmed that the level of GPC3 expression was responsible for CTL recognition and that subtoxic‐dose chemotherapy made tumor cells more susceptible to the cytotoxic effect of CTL. Thus, it might be possible to treat ovarian CCC patients by combining chemotherapy with immunotherapy. Our data suggest that GPC3 could be an effective target for immunotherapy against ovarian CCC. (Cancer Sci 2011; 102: 1622–1629)

Identification of glypican-3-derived long peptides activating both CD8+ and CD4+ T cells; prolonged overall survival in cancer patients with Th cell response

In a recent phase I clinical trial, a vaccine consisting of glypican-3 (GPC3)-derived CTL epitopes was found to be safe and induced measurable immune and clinical responses in patients with hepatocellular carcinoma (HCC). The aim of this study was to identify GPC3-derived long peptides (GPC3-LPs) carrying promiscuous HLA class II-restricted T helper (Th) cell epitopes. Using a computer algorithm, we predicted GPC3-LPs that can bind to promiscuous HLA class II molecules. Their antigenicity for induction of specific CD4+ T cells in healthy donors or patients with HCC, before and after vaccination with GPC3-SPs, was proven by IFNγ enzyme-linked immunospot assays. Natural processing of these epitopes was confirmed by the immune response of helper T cells to dendritic cells (DCs) loaded with GPC3 proteins. Cross-presentation capacity was assessed in vitro using human DCs and LPs encapsulated in liposomes and in vivo in HLA-A2 transgenic mice (Tgm). All five LPs could induce Th1 cells and were presented by several frequently occurring HLA class II molecules in vitro. Four of them were likely to be naturally processed. One of the LPs encapsulated in liposomes was well cross-presented in vitro; it cross-primed CTLs in HLA-A2 Tgm. LP-specific and HLA class II-restricted CD4+ T-cell responses were observed in 14 of 20 HCC patients vaccinated with GPC3-SPs. Repeated vaccinations enhanced GPC3-LP-specific responses in 8 of 13 patients with HCC. Moreover, the presence of the specific Th cell was correlated with prolonged overall survival (OS). GPC3-LPs can be useful for cancer immunotherapy.