Until now, three types of well-recognized cancer treatments have been developed, i.e., surgery, chemotherapy, and radiotherapy; these either remove or directly attack the cancer cells. These treatments can cure cancer at earlier stages but are frequently ineffective for treating cancer in the advanced or recurrent stages. Basic and clinical research on the tumor microenvironment, which consists of cancerous, stromal, and immune cells, demonstrates the critical role of antitumor immunity in cancer development and progression. Cancer immunotherapies have been proposed as the fourth cancer treatment. In particular, clinical application of immune checkpoint inhibitors, such as anti-CTLA-4 and anti-PD-1/PD-L1 antibodies, in various cancer types represents a major breakthrough in cancer therapy. Nevertheless, accumulating data regarding immune checkpoint inhibitors demonstrate that these are not always effective but are instead only effective in limited cancer populations. Indeed, several issues remain to be solved to improve their clinical efficacy; these include low cancer cell antigenicity and poor infiltration and/or accumulation of immune cells in the cancer microenvironment. Therefore, to accelerate the further development of cancer immunotherapies, more studies are necessary. In this review, we will summarize the current status of cancer immunotherapies, especially cancer vaccines, and discuss the potential problems and solutions for the next breakthrough in cancer immunotherapy.

中文翻译：

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癌症疫苗：迈向癌症免疫治疗的下一个突破


迄今为止，已经开发出三种公认的癌症治疗方法，即手术、化疗和放疗。这些药物可以去除或直接攻击癌细胞。这些治疗可以治愈早期阶段的癌症，但对于治疗晚期或复发阶段的癌症通常无效。对由癌细胞、基质细胞和免疫细胞组成的肿瘤微环境的基础和临床研究证明了抗肿瘤免疫在癌症发生和进展中的关键作用。癌症免疫疗法已被提议作为第四种癌症治疗方法。特别是免疫检查点抑制剂，例如抗CTLA-4和抗PD-1/PD-L1抗体在各种癌症类型中的临床应用，代表了癌症治疗的重大突破。然而，有关免疫检查点抑制剂的不断积累的数据表明，这些抑制剂并不总是有效，而是仅对有限的癌症人群有效。事实上，为了提高其临床疗效，仍有几个问题需要解决；这些包括癌细胞抗原性低以及癌症微环境中免疫细胞的浸润和/或积累不良。因此，为了加速癌症免疫疗法的进一步发展，需要更多的研究。在这篇综述中，我们将总结癌症免疫治疗尤其是癌症疫苗的现状，并讨论癌症免疫治疗下一步突破的潜在问题和解决方案。