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Acquired resistance during adoptive cell therapy by transcriptional silencing of immunogenic antigens.

ABSTRACT: Immunotherapies such as adoptive cell therapy (ACT) are promising treatments for solid cancers. However, relapsing disease remains a problem and the molecular mechanisms underlying resistance are poorly defined. We postulated that the deregulated epigenetic landscape in cancer cells could underpin the acquisition of resistance to immunotherapy. To address this question, two preclinical models of ACT were employed to study transcriptional and epigenetic regulatory processes within ACT-treated cancer cells. In these models ACT consistently causes robust tumor regression, but resistance develops and tumors relapse. We identified down-regulated expression of immunogenic antigens at the mRNA level correlated with escape from immune control. To determine whether this down-regulation was under epigenetic control, we treated escaped tumor cells with DNA demethylating agents, azacytidine (AZA) and decitabine (DEC). AZA or DEC treatment restored antigen expression in a proportion of the tumor population. To explore the importance of other epigenetic modifications we isolated tumor cells refractory to DNA demethylation and screened clones against a panel of 19 different epigenetic modifying agents (EMAs). The library of EMAs included inhibitors of a range of chromosomal and transcription regulatory protein complexes, however, when tested as single agents none restored further antigen expression. These findings suggest that tumor cells employ multiple epigenetic and genetic mechanisms to evade immune control, and a combinatorial approach employing several EMAs targeting transcription and genome stability may be required to overcome tumor resistance to immunotherapy.

SUBMITTER: Wylie B

PROVIDER: S-EPMC6682399 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Acquired resistance during adoptive cell therapy by transcriptional silencing of immunogenic antigens.

Wylie Ben B Chee Jonathan J Forbes Catherine A CA Booth Mitchell M Stone Shane R SR Buzzai Anthony A Abad Ana A Foley Bree B Cruickshank Mark N MN Waithman Jason J

Oncoimmunology 20190603 8

Immunotherapies such as adoptive cell therapy (ACT) are promising treatments for solid cancers. However, relapsing disease remains a problem and the molecular mechanisms underlying resistance are poorly defined. We postulated that the deregulated epigenetic landscape in cancer cells could underpin the acquisition of resistance to immunotherapy. To address this question, two preclinical models of ACT were employed to study transcriptional and epigenetic regulatory processes within ACT-treated can ...[more]

PMID: 31413920

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Project description:Cancer immunotherapy including adoptive T cell therapy (ACT) is widely used in the clinic and is highly beneficial for patients with hematological malignancies; however, it remains a challenge to develop effective immunotherapy strategies for the treatment of solid cancers, due to the inefficiency of the immune response and the immunosuppressive tumor microenvironment (TME). Immunogenic cell death (ICD) converts dying cancer cells into a therapeutic vaccine and stimulate a systemic antigen-specific antitumor immune response, which can effectively subvert the immunosuppressive TME and enhance the efficiency of immune responses, relative to conventional immunotherapeutic regimens. However, the application of traditional inducers of ICD in anti-cancer immunotherapy has been limited because of low levels of ICD induction and a lack of tumor-targeting accumulation. Mitochondria are important for tumor-targeting strategies and have emerged as organelles with key roles in the immune system. We hypothesized that the alteration of mitochondria in cancer cells could be an important target for the development of an efficient ICD inducer for use in cancer immunotherapy. Here, we report the evaluation of a mitochondria-targeted small molecule, IR-780, that acts as an ICD inducer and exhibits exceptional antineoplastic activity. IR-780 specifically accumulated in tumor cells to elicit ICD in vitro and in vivo, effectively suppressed tumor growth and lung metastasis, and enhanced adoptive T-cell therapy effects against solid tumors in mouse models. These anticancer effects were linked to dendritic cell maturation and synergistic effector T cell priming and infiltration into tumors. The underlying mechanism involves the direct targeting of the mitochondria by IR-780, to destroy cancer cells, including drug-resistant cancer cells, leading to the full exposure of tumor-associated antigens (TAAs), thereby enhancing antigen-specific antitumor immune responses. These features of IR-780 suggest that it has the advantage of leading to complete TAA exposure and the stimulation of efficient antitumor immune responses in the TME. IR-780 has potential for use as a preparative ICD inducer, in combination with conventional immunostimulatory regimens for cancer immunotherapy, particularly in the context of solid tumor treatment.

Project description:Candida lusitaniae is usually susceptible to echinocandins. Beta-1,3-glucan synthase encoded by FKS genes is the target of echinocandins. A few missense mutations in the C. lusitaniae FKS1 hot spot 1 (HS1) have been reported. We report here the rapid emergence of antifungal resistance in C. lusitaniae isolated during therapy with amphotericin B (AMB), caspofungin (CAS), and azoles for treatment of persistent candidemia in an immunocompromised child with severe enterocolitis and visceral adenoviral disease. As documented from restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) analysis, the five C. lusitaniae isolates examined were related to each other. From antifungal susceptibility and molecular analyses, 5 different profiles (P) were obtained. These profiles included the following: profile 1 (P1) (CAS MIC [μg/ml], 0.5; fluconazole [FLC] MIC, 0.25), determined while the patient was being treated with liposomal AMB for 3 months; P2 (FLC MIC [μg/ml], 0.25; CAS MIC, 4), while the patient was being treated with CAS for 2 weeks; P3 (CAS MIC [μg/ml], 0.5; FLC MIC, 32), while the patient was being treated with azoles and CAS initially followed by azoles alone for a week; P4 (CAS MIC [μg/ml], 8; FLC MIC, 8), while the patient was being treated with both drugs for 3 weeks; and P5 (AMB MIC [μg/ml], 0.125; CAS MIC, 8), while the patient was being treated with AMB and FLC for 2 weeks. CAS resistance was associated with resistance not only to micafungin and anidulafungin but also to AMB. Analysis of CAS resistance revealed 3 novel FKS1 mutations in CAS-resistant isolates (S638Y in P2; S631Y in P4; S638P in P5). While S638Y and -P are within HS1, S631Y is in close proximity to this domain but was confirmed to confer candin resistance using a site-directed mutagenesis approach. FLC resistance could be linked with overexpression of major facilitator gene 7 (MFS7) in C. lusitaniae P2 and P4 and was associated with resistance to 5-flurocytosine. This clinical report describes resistance of C. lusitaniae to all common antifungals. While candins or azole resistance followed monotherapy, multidrug antifungal resistance emerged during combined therapy.

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Acquired resistance during adoptive cell therapy by transcriptional silencing of immunogenic antigens.

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Acquired resistance during adoptive cell therapy by transcriptional silencing of immunogenic antigens.

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