Anti-programmed cell death protein-1/ligand-1 therapy in different cancers

Immunologic checkpoint blockade with antibodies against the programmed cell death protein-1 (PD-1) or its ligand (PD-L1) is an effective method for reversing cancer immunosuppression and thereby promoting immune responses against several cancer types. Anti-PD-1 and anti-PD-L1 antibodies have resulted in long-term responses with minimal side effects in significant numbers of patients with melanoma, lung, kidney, bladder and triple-negative breast cancer, as well as in chemotherapy-refractory Hodgkin disease. There is already evidence from at least one randomised trial that anti-PD-1 therapy is superior to chemotherapy in the treatment of patients with metastatic melanoma, and two anti-PD-1 antibodies, pembrolizumab and nivolumab, have been approved by the US Food and Drug Administration for the treatment of patients previously treated for metastatic melanoma. It is anticipated that approvals by drug regulatory bodies will be forthcoming in several cancers in the next months.Blockade of cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 or its ligand (PD-1/L1) represent a paradigm shift in immunotherapy for cancer, as it focus on the disinhibition of native immune responses instead of the prior focus in activation of the immune system with tumour vaccines or recombinant cytokines. Among the most promising approaches to activating therapeutic antitumour immunity is the blockade of immune checkpoints. CTLA-4 was the first negative regulatory checkpoint receptor to be clinically targeted. CTLA-4 is upregulated early during the T-cell activation and its expression dampens T cells by outcompeting CD28 in binding CD80 and CD86 (Linsley et al, 1994; Egen and Allison, 2002; Riley et al, 2002). Antibodies that block CTLA-4 enhance immune responses by activating effector T cells, but probably also by interacting with other immune cells such as regulatory T cells (Tregs), which exhibit immunosuppressive properties (Lenschow et al, 1996; Wing et al, 2008). The anti-CTLA-4 antibody ipilimumab (Yervoy; Bristol-Myers Squibb, Princeton, NJ, USA) showed a significant overall survival (OS) improvement in patients with advanced melanoma in two randomised phase III trials (Hodi et al, 2010; Robert et al, 2011), and was approved by the US Food and Drug Administration (FDA) and other drug regulatory bodies in 2011. The broad activation of the immune system and deregulation of an immunologic homoeostasis achieved by blocking CTLA-4 might be responsible for the development of inflammatory or autoimmune toxicities, reported in ∼15% of the patients (Robinson et al, 2004).In contrast, PD-1 appears to have a prominent role in modulating T-cell activity in peripheral tissues via interaction with its ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC). Programmed cell death protein-1 is an immune checkpoint receptor that prevents overstimulation of immune responses and contributes to the maintenance of immune tolerance to self-antigens (Freeman et al, 2000; Keir et al, 2006; Korman et al, 2006; Okazaki and Honjo, 2007). Upon antigen recognition, activated T cells express PD-1 on their surface and produce interferons that lead to the expression of PD-L1 in multiple tissues, including cancer (Ishida et al, 1992; Pardoll, 2012). Binding of PD-1 to its ligands limits effector T-cell activity, and therefore regulating detrimental immune responses and preventing autoimmunity (Topalian et al, 2012a). Programmed cell death protein-1 is not only induced on effector T cells but also on Tregs (Francisco et al, 2009), activated B cells and natural killer cells (Terme et al, 2011), suggesting its contribution to other important immune cell functions.Besides the interaction between CTLA-4 and PD-1 with their respective ligands, other costimulatory and inhibitory interactions regulate T-cell responses. Although not the focus of the current review, examples of promising inhibitors of immune checkpoint targets that are being pursued clinically using blocking antibodies include the lymphocyte-activation gene 3, the T-cell membrane protein 3 or the adenosine receptor A2aR.     

Immunogenic cell death in colon cancer prevention and therapy

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. The colonic mucosa constitutes a critical barrier and a major site of immune regulation. The immune system plays important roles in cancer development and treatment, and immune activation caused by chronic infection or inflammation is well-known to increase cancer risk. During tumor development, neoplastic cells continuously interact with and shape the tumor microenvironment (TME), which becomes progressively immunosuppressive. The clinical success of immune checkpoint blockade therapies is limited to a small set of CRCs with high tumor mutational load and tumor-infiltrating T cells. Induction of immunogenic cell death (ICD), a type of cell death eliciting an immune response, can therefore help break the immunosuppressive TME, engage the innate components, and prime T cell-mediated adaptive immunity for long-term tumor control. In this review, we discuss the current understanding of ICD induced by antineoplastic agents, the influence of driver mutations, and recent developments to harness ICD in colon cancer. Mechanism-guided combinations of ICD-inducing agents with immunotherapy and actionable biomarkers will likely offer more tailored and durable benefits to patients with colon cancer.     

Retinoid/arsenic combination therapy of promyelocytic leukemia: induction of telomerase-dependent cell death.

Acute promyelocytic leukemia (APL) is efficiently treated with a cell differentiation inducer, all-trans retinoic acid (ATRA). However, a significant percentage of patients still develop resistance to this treatment. Recently, arsenic trioxide (As2O3), alone or in combination with ATRA, has been identified as an alternative therapy in patients with both ATRA-sensitive and ATRA-resistant APL. Previous investigations restricted the mechanism of this synergism to the modulation and/or degradation of PML-RARalpha oncoprotein through distinct pathways. In this study, using several ATRA maturation-resistant APL cell lines, we demonstrate in vitro that the success of ATRA/As2O3 treatment in APL pathology can be explained, at least in part, by a synergistic effect of these two drugs in triggering downregulation of telomerase efficient enough to cause telomere shortening and subsequent cell death. Such long-term low-dose combinatorial therapy strategies, developed also to avoid acute side effects, reinforce the notion that the antitelomerase strategy, based on a combination of active agents, should now be considered and evaluated not only in APL but also in other malignancies.     

Shikonin exerts antitumor activity via proteasome inhibition and cell death induction in vitro and in vivo

Dysregulation of the ubiquitin‐proteasome pathway plays an essential role in tumor growth and development. Shikonin, a natural naphthoquinone isolated from the traditional Chinese medicine Zi Cao (gromwell), has been reported to possess tumor cell‐killing activity, and results from a clinical study using a shikonin‐containing mixture demonstrated its safety and efficacy for the treatment of late‐stage lung cancer. In this study, we reported that shikonin is an inhibitor of tumor proteasome activity in vitro and in vivo. Our computational modeling predicts that the carbonyl carbons C₁ and C₄ of shikonin potentially interact with the catalytic site of β5 chymotryptic subunit of the proteasome. Indeed, shikonin potently inhibits the chymotrypsin‐like activity of purified 20S proteasome (IC₅₀ 12.5 μmol/L) and tumor cellular 26S proteasome (IC₅₀ between 2–16 μmol/L). Inhibition of the proteasome by shikonin in murine hepatoma H22, leukemia P388 and human prostate cancer PC‐3 cultures resulted in accumulation of ubiquitinated proteins and several proteasome target proapoptotic proteins (IκB‐α, Bax and p27), followed by induction of cell death. Shikonin treatment resulted in tumor growth inhibition in both H22 allografts and PC‐3 xenografts, associated with suppression of the proteasomal activity and induction of cell death in vivo. Finally, shikonin treatment significantly prolonged the survival period of mice bearing P388 leukemia. Our results indicate that the tumor proteasome is one of the cellular targets of shikonin and inhibition of the proteasome activity by shikonin contributes to its antitumor property. © 2008 Wiley‐Liss, Inc.     

In situ thermal ablation augments antitumor efficacy of adoptive T cell therapy

Abstract

Purpose: The aim of this study is to investigate whether radiofrequency ablation (RFA) improves the efficacy of adoptive T cell immunotherapy in preclinical mouse cancer models.

Method: Mice implanted subcutaneously (sc) with syngeneic colon adenocarcinoma or melanoma were treated with sub-curative in situ RFA (90?°C, 1?min). Trafficking of T cells to lymph nodes (LN) or tumors was quantified by homing assays and intravital microscopy (IVM) after sham procedure or RFA. Expression of trafficking molecules (CCL21 and intercellular adhesion molecule-1 [ICAM-1]) on high endothelial venules (HEV) in LN and tumor vessels was evaluated by immunofluorescence microscopy. Tumor-bearing mice were pretreated with RFA to investigate the therapeutic benefit when combined with adoptive transfer of in vitro-activated tumor-specific CD8⁺ T cells.

Results: RFA increased trafficking of naïve CD8⁺ T cells to tumor-draining LN (TdLN). A corresponding increase in expression of ICAM-1 and CCL21 was detected on HEV in TdLN but not in contralateral (c)LN. IVM revealed that RFA substantially enhanced secondary firm arrest of lymphocytes selectively in HEV in TdLN. Furthermore, strong induction of ICAM-1 in tumor vessels was associated with significantly augmented trafficking of adoptively transferred in vitro-activated CD8⁺ T cells to tumors after RFA. Finally, preconditioning tumors with RFA augmented CD8⁺ T cell-mediated apoptosis of tumor targets and delayed growth of established tumors when combined with adoptive T cell transfer immunotherapy.

Conclusions: These studies suggest that in addition to its role as a palliative therapeutic modality, RFA may have clinical potential as an immune-adjuvant therapy by augmenting the efficacy of adoptive T cell therapy.     

Artesunate induces oncosis-like cell death in vitro and has antitumor activity against pancreatic cancer xenografts in vivo

Pancreatic cancer is highly resistant to the currently available chemotherapeutic agents. Less than 5% of patients diagnosed with this disease could survive beyond 5 years. Thus, there is an urgent need for the development of novel, efficacious drugs that can treat pancreatic cancer. Herein we report the identification of artesunate (ART), a derivative of artemisinin, as a potent and selective antitumor agent against human pancreatic cancer cells in vitro and in vivo. ART exhibits selective cytotoxic activity against Panc-1, BxPC-3 and CFPAC-1 pancreatic cancer cells with IC₅₀ values that are 2.3- to 24-fold less than that of the normal human hepatic cells (HL-7702). The pan caspase inhibitor zVAD-fmk did not inhibit the cytotoxic activity of ART. Electron microscopy of ART-treated cells revealed severe cytoplasmic swelling and vacuolization, swollen and internally disorganized mitochondria, dilation (but not fragmentation) of the nuclei without chromatin condensation, and cell lysis, yielding a morphotype that is typical of oncosis. The ART-treated cells exhibited a loss of mitochondrial membrane potential (ΔΨm) and ART-induced cell death was inhibited in the presence of the reactive oxygen species (ROS) scavenger N-acetyl-cysteine (NAC). Importantly, ART produced a dose-dependent tumor regression in an in vivo pancreatic cancer xenografts model. The in vivo antitumor activity of ART was similar to that of gemcitabine. Taken together, our study suggests that ART exhibits antitumor activity against human pancreatic cancer via a novel form of oncosis-like cell death, and that ART should be considered a potential therapeutic candidate for treating pancreatic cancer.     

Ultrasound diagnosis of angiopathy in antitumor therapy

The ultrasound characteristics of arterial walls were assessed in 78 young and middle-aged male (42) and female (36) cancer patients (mean age 36 +/- 0.9) receiving radiation and/or polychemotherapy. The study was specifically concerned with quantitative and qualitative changes in the "intima-media" complex and the vasoactive dysfunction of the endothelium. We established the ultrasound characteristics of arterial walls, in particular, the damage done to the complex in the arteries in exposed sites, and angiopathies as a systemic manifestation of vasoactive dysfunction (polychemotherapy) or the combined effect on the vascular wall radiopolychemotherapy, vis-a-vis each therapeutic modality, separately and in combination.     

Recent advances in understanding the cell death pathways activated by anticancer therapy

Over the past two decades, the role of apoptosis in the cytotoxicity of anticancer drugs has become clear. Apoptosis may occur via a death receptor-dependent (extrinsic) or independent (intrinsic or mitochondrial) pathway. Mitochondria play a central role in cell death in response to DNA damage, and mediate the interaction(s) of various cytoplasmic organelles, including the endoplasmic reticulum, Golgi apparatus, and lysosomes. The mitochondrial pathway of cell death is mediated by Bcl-2 family proteins, a group of antiapoptotic and proapoptotic proteins that regulate the passage of small molecules, such as cytochrome c, Smac/Diablo, and apoptosis-inducing factor, which activates caspase cascades, through the mitochondrial transition pore. In addition, apoptosis can induce autophagic cell death via crosstalk between the two pathways upon treatment with anticancer drugs. The current review focused on recent advances surrounding the mechanism(s) of cell death induced by anticancer agents and discussed potential molecular targets for enhancing the chemotherapeutic effect(s) of anticancer agents.     

EGFR家族靶向肿瘤治疗研究进展

表皮生长因子受体（EGFR）家族的异常表达和活化,与肿瘤的发生、发展及恶性生物学行为关系密切。EGFR家族靶向治疗是目前肿瘤治疗领域研究的热点之一,并在临床治疗方面显示出良好的前景。现就该方面研究的最新进展作一综述。     

Recombinant interleukin-12 and interleukin-18 antitumor therapy in a guinea-pig hepatoma cell implant model

Interleukin (IL)-12 and IL-18 are secreted by myeloid cells activated with adjuvants such as Bacillus Calmette-Guérin (BCG) cell wall. They induce T-helper 1 polarization in the host immune system and upregulate production of lymphocyte interferon-γ, which leads to the induction of an antitumor gene program. It has been reported that humans have an immune system that more closely resembles that of the guinea pig in adjuvant-response features rather than the mouse system, which prevents the mouse results being extrapolated to human immunotherapy. Here we have constructed a tumor-implant system in guinea pigs to evaluate the antitumor potential of guinea pig IL-12 (gpIL-12) and guinea pig IL-18 (gpIL-18). Purified recombinant gpIL-12 and gpIL-18 were prepared and applied intraperitoneally to tumor-bearing (line 10 hepatoma) guinea pigs as the basis of the adjuvant immunotherapy. Intraperitoneal administration of gpIL-12 and gpIL-18 led to retardation of primary tumor growth and suppression of lymph-node metastasis in tumor-bearing guinea pigs. The permissible range of IL-12 appeared wider in guinea pigs than in mice. Even at an IL-12 dose higher than that in mice, there was no evidence of side-effects until day 26, when the guinea pigs were killed. gpIL-18 augmented the antitumor effect of gpIL-12 but exerted less ability to suppress lymph-node metastasis. The effects of gpIL-12 and gpIL-18 on the tumors implanted in guinea pigs will encourage us to use IL-12- and IL-18-inducible adjuvants for immunotherapy in human patients with solid cancer. ( Cancer Sci 2007; 98: 1936–1942)     

Application of the Cre recombinase/loxP system further enhances antitumor effects in cell type-specific gene therapy against carcinoembryonic antigen-producing cancer.

A considerable number of studies of cancer have shown that the cell type-specific promoter is an effective tool for selective expression of foreign genes in tumor cells. However, few reports have demonstrated significant in vivo antitumor effects using this strategy thus far, possibly because the low activity of such a promoter results in insufficient expression of genes in cancer cells as well as in insignificant antitumor effects, even when the cells are infected by highly efficient gene transfer methods. To overcome this problem, we used the Cre/loxP system for the cell type-specific gene therapy against carcinoembryonic antigen (CEA)-producing cancer. We constructed a pair of recombinant Ads. One expresses the Cre recombinase (Cre) gene under the control of the CEA promoter (Ad.CEA-Cre). The other contains the herpes simplex virus thymidine kinase (HSV-TK) gene separated from the strong CAG promoter by insertion of the neomycin resistance (neo) gene (Ad.lox-TK). The HSV-TK gene of the latter Ad is designed to be activated through excisional deletion of the neo gene by Cre enzyme released from the former one only when CEA-producing cells are infected simultaneously with these Ads. Coinfection by these Ads rendered a human CEA-producing cancer cell line 8.4-fold more sensitive to ganciclovir (GCV) compared with infection by Ad.CEA-TK alone, the HSV-TK gene of which is directly regulated by the CEA promoter. On the other hand, coinfection with these Ads did not significantly change the GCV sensitivity of non-CEA-producing cells. Intratumoral injection of Ad.CEA-Cre combined with Ad.lox-TK followed by GCV treatment almost completely eradicated CEA-producing tumors established in the subcutis of athymic mice, whereas intratumoral injection of Ad.CEA-TK with GCV administration at most retarded the growth of inoculated tumors. These results suggest distinct advantages of the Cre/loxP system applied in the conventional cell type-specific gene therapy against cancer.     

SMAC/Diablo controls proliferation of cancer cells by regulating phosphatidylethanolamine synthesis

SMAC/Diablo, a pro‐apoptotic protein, yet it is overexpressed in several cancer types. We have described a noncanonical function for SMAC/Diablo as a regulator of lipid synthesis during cancer cell proliferation and development. Here, we explore the molecular mechanism through which SMAC/Diablo regulates phospholipid synthesis. We showed that SMAC/Diablo directly interacts with mitochondrial phosphatidylserine decarboxylase (PSD) and inhibits its catalytic activity during synthesis of phosphatidylethanolamine (PE) from phosphatidylserine (PS). Unlike other phospholipids (PLs), PE is synthesized not only in the endoplasmic reticulum but also in mitochondria. As a result, PSD activity and mitochondrial PE levels were increased in the mitochondria of SMAC/Diablo‐deficient cancer cells, with the total amount of cellular PLs and phosphatidylcholine (PC) being lower as compared to SMAC‐expressing cancer cells. Moreover, in the absence of SMAC/Diablo, PSD inhibited cancer cell proliferation by catalysing the overproduction of mitochondrial PE and depleting the cellular levels of PC, PE and PS. Additionally, we demonstrated that both SMAC/Diablo and PSD colocalization in the nucleus resulted in increased levels of nuclear PE, that acts as a signalling molecule in regulating several nuclear activities. By using a peptide array composed of 768‐peptides derived from 11 SMAC‐interacting proteins, we identified six nuclear proteins ARNT, BIRC2, MAML2, NR4A1, BIRC5 and HTRA2 Five of them also interacted with PSD through motifs that are not involved in SMAC binding. Synthetic peptides carrying the PSD‐interacting motifs of these proteins could bind purified PSD and inhibit the PSD catalytic activity. When targeted specifically to the mitochondria or the nucleus, these synthetic peptides inhibited cancer cell proliferation. To our knowledge, these are the first reported inhibitors of PSD acting also as inhibitors of cancer cell proliferation. Altogether, we demonstrated that phospholipid metabolism and PE synthesis regulated by the SMAC‐PSD interaction are essential for cancer cell proliferation and may be potentially targeted for treating cancer.     

Differential cell death response to photodynamic therapy is dependent on dose and cell type

PDT-induced cell death, by either apoptosis or necrosis may vary with cell type or PDT dose. 5 cell types were treated with varying doses of aminolaevulinic acid-induced PDT and the type of cell death analysed. The mode of cell death was found to depend on both cell type and light dose.     

Serum biomarkers of cell death for monitoring therapy response of gastrointestinal carcinomas

PurposeAntitumour treatments are thought to exert their therapeutic efficacy mainly by induction of apoptosis in tumour cells. In epithelial cells, caspases, the key enzymes of apoptosis, cleave the intermediate filament protein cytokeratin (CK)-18 into specific fragments that are released into circulating blood and can be detected by a specific ELISA.Experimental designTo investigate the use of CK-18 fragments as a potential biomarker for the treatment response, we examined the association of serum CK-18 levels and clinical response in 35 patients with gastrointestinal cancers.ResultsWhile both cleaved and total CK-18 levels were intrinsically elevated in tumour patients, they were further increased during 5-fluorouracil (5-FU)-based therapy. Importantly, the increased levels of CK-18 could discriminate between patients with different clinical response. Cancer patients with a partial response or stable disease revealed a significantly higher increase of cleaved CK-18 during chemotherapy as compared to patients with progressive disease.ConclusionsOur results suggest that detection of circulating caspase-cleaved CK-18 might be a useful serum biomarker for monitoring treatment response and should merit further evaluation in larger patient groups.     

Current situation of programmed cell death protein 1/programmed cell death ligand 1 inhibitors in advanced triple-negative breast cancer

Triple-negative breast cancer(TNBC) has the worst prognosis among all molecular types of breast cancer. Because of the strong immunogenicity of TNBC cells, programmed death 1/programmed death ligand 1(PD-1/PD-L1)inhibitors, two kinds of immune checkpoint blockade agents, might help improve the prognosis of TNBC.However, how to better use PD-1/PD-L1 inhibitors and select patients who may benefit from treatment options remains controversial. This article summarizes published clinical studies in wh...     

Diffusion-weighted MRI for imaging cell death after cytotoxic or apoptosis-inducing therapy

Background:

Non-invasive serial imaging is desirable to detect processes such as necrotic and apoptotic cell death in cancer patients undergoing treatment. This study investigated the use of diffusion-weighted (DW-) magnetic resonance imaging (MRI) for imaging cell death induced by either a cytotoxic drug (irinotecan), or the apoptosis-inducing agent birinapant, in human tumour xenografts in vivo.

Methods:

Nude mice bearing human SW620 colon carcinoma xenografts were treated with vehicle, irinotecan (50 mg kg⁻¹) or birinapant (30 mg kg⁻¹) for up to 5 days. DW-MRI was performed prior to and on days 1, 3 and 5 during treatment. Assessment of tumour apoptosis and necrosis ex vivo was used to validate the imaging findings.

Results:

Both irinotecan and birinapant induced significant tumour growth delay. Irinotecan induced a small increase in the tumour apparent diffusion coefficient (ADC) after 1 day, with a 20 and 30% increase at days 3 and 5 respectively. ADC was unchanged in the vehicle- and birinapant-treated tumours despite a growth delay in the latter. Histological analysis showed that irinotecan increased necrosis at days 3 and 5, and induced apoptosis after 1 day, compared with vehicle. Birinapant induced apoptosis after day 3, but had no effect on tumour necrosis.

Conclusions:

Tumour ADC changes after irinotecan treatment were associated with the induction of a mixture of necrotic and apoptotic cell death, whereas induction of apoptosis alone with birinapant was not sufficient to induce changes in tissue microstructure that were detectable with DW-MRI. ADC is a useful non-invasive biomarker for early detection of response to cytotoxic drugs, but false negatives may arise while detecting apoptotic response to birinapant.