免疫微环境关乎滤泡性淋巴瘤预后

《临床肿瘤学杂志》发表的一项研究结果显示，淋巴结中免疫细胞内的肿瘤诱导性遗传学变化，可预测滤泡性淋巴瘤患者的结局(J. Clin. Oncol. 2013;31:2654-61)。

研究者对来自172例初治滤泡性淋巴瘤患者淋巴结活检标本的肿瘤浸润性T细胞(TIL)和来自12名健康志愿者外周血、反应性扁桃体的T细胞进行了基因表达谱分析。主要研究者、英国伦敦医学与牙医学院的Shahryar Kiaii博士报告称，与健康志愿者的T细胞相比，TIL中存在多种基因上调或下调的现象，并且运动性受损。此外，在暴露于淋巴瘤细胞的情况下，健康T细胞也可被诱导出相似的遗传学改变。淋巴结内基因表达发生改变的TIL的数量和分布，可预测总生存率和转化为B细胞淋巴瘤的时间。

“上述结果有助于我们理解淋巴瘤细胞、TIL与巨噬细胞在微环境中的复杂相互作用，而且有助于我们提出假说。但是在我们更好地理解这些相互作用之前，似乎还不能根据TIL免疫组化分析判断滤泡性淋巴瘤预后。不过，由于非恶性浸润性免疫细胞在滤泡性淋巴瘤的结局中扮演着关键角色，只有理解了患者TIL中遗传学异常的本质和影响之后，才有可能发展出可以改变滤泡性淋巴瘤微环境的免疫治疗策略。”

在这项研究中，Kiaii博士及其同事研发出了组织芯片，并根据mRNA表达特征、实时PCR检测和免疫组化结果评估高度纯化CD4和CD8 T细胞中的基因表达。

结果显示，与健康T细胞相比，TIL具有异常的基因表达特征：表达上调最明显的基因涉及，前黑色素聚集激素(PMCH)、ETS易位突变1(ETV1)和肿瘤坏死因子受体超家族成员9(TNFRSF9)。表达下调最明显的是编码细胞骨架辅肌动蛋白(ACTN1)的基因，而且这些TIL的运动性比健康T细胞明显减弱(P＜0.025)。

在单独培养的情况下，健康T细胞并不表达PMCH并且运动性正常。但当与滤泡淋巴瘤细胞共同培养时，健康T细胞会高度表达这种蛋白且运动性减弱(P=0.0002)。

通过免疫组化检查确定的表达PMCH、ETV1和NAMPT(尼克酰胺转磷酸核糖激酶)TIL的数量及其在淋巴结中的位置——在恶性滤泡中(滤泡内区域)、在滤泡间区域，以及弥漫分布——与总生存率和至转化时间均显著相关。

多变量分析显示，表达PMCH的细胞的滤泡间/滤泡内比率+滤泡内区域NAMPT高表达和ETV1低表达，是至转化时间较长的最强预测因素[危险比(HR)，0.19；P=0.003]。与之相似，滤泡内区域中表达PMCH和NAMPT的细胞数量+ ETV1细胞的滤泡间/滤泡内比率，是总生存率较高的最前预测因素(HR，0.32；P=0.007)。

这项研究获得了英国癌症研究所和美国国立癌症研究所的支持。一名研究者披露称接受了罗氏/基因泰克和Celgene提供的酬金。

随刊述评：需要针对B细胞双管齐下

罗切斯特梅奥医院的Stephen M. Ansell医生在随刊述评中指出，在开发针对B细胞恶性肿瘤的新型T细胞介导性治疗的当下，这项研究的结果显得尤为重要(J. Clin. Oncol. 2013;31:2641-2)。

淋巴瘤细胞常会通过消除肿瘤特异性T细胞或使其失活而诱导免疫耐受。为了克服这一点，人们有多种尝试，嵌合抗原受体(CAR)治疗就是其中之一，然而仅有肿瘤负荷较低且之前曾接受细胞毒化疗的患者能从中获益。这种化疗似乎不仅会消耗恶性细胞，也会减少免疫抑制细胞。恶性B细胞及其促成的免疫抑制性肿瘤微环境，可能仍是妨碍过继性免疫疗法有效治疗B细胞淋巴瘤的障碍，尤其是在化疗耐药的巨块肿瘤患者中。


Stephen Ansell医生

上述数据证明，恶性B细胞可促进免疫抑制性微环境的形成，从而避免其自身成为免疫系统的靶点。未来针对滤泡性淋巴瘤的治疗，包括诸如CAR T细胞等免疫抑制治疗，将不仅需要消耗恶性B细胞，还要能克制恶性B细胞对抗肿瘤免疫应答的抑制作用。既能减少恶性细胞、又能提升免疫功能的双管齐下治疗，将会给滤泡性淋巴瘤患者带来更好的临床结局。

Ansell医生报告称无相关利益冲突。

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By: SUSAN LONDON, Oncology Practice

Tumor-induced genetic changes in the immune cells of lymph nodes predict outcomes in patients with follicular lymphoma, according to a study published in the Journal of Clinical Oncology.

Investigators performed gene expression profiling of tumor-infiltrating T cells (TILs) from lymph node biopsies at diagnosis in 172 treatment-naive patients with follicular lymphoma and of T cells from reactive tonsils and peripheral blood of 12 healthy donors.

Compared with the T cells from healthy donors, the TILs had marked upregulation of several genes and downregulation of others, as well as impaired motility. Moreover, similar changes could be induced in healthy T cells by exposing them to lymphoma cells, said Dr. Shahryar Kiaii of the Institute of Cancer and Barts and the London School of Medicine and Dentistry and his associates.

The numbers and locations within the lymph nodes of the TILs showing altered gene expression predicted both overall survival and the time to transformation to B-cell lymphoma – sometimes dramatically. Certain combinations were associated with 70%-80% reductions in the risks of these outcomes.

"These results contribute to our understanding of the complex interactions of lymphoma cells, TILs, and macrophages in their microenvironment and help us generate hypotheses. But until we have a better understanding of these interactions, it does not yet seem feasible to incorporate [immunohistochemistry] analysis of TILs in [follicular lymphoma] for prognosis," the investigators wrote.

"However, because nonmalignant infiltrating immune cells play a crucial role in outcomes in [follicular lymphoma], understanding the nature and impact of the abnormalities induced in TILs in these patients is vital before any immunotherapeutic strategies can be implemented to alter the immune microenvironment in [follicular lymphoma]," they added.

In the study, the investigators constructed tissue microarrays and used mRNA expression profiles, real-time polymerase chain reaction assays, and immunohistochemistry to assess gene expression in highly purified CD4 and CD8 T cells.

Results showed that the TILs had an abnormal gene expression profile when compared with the healthy T cells, Dr. Kiaii and his associates said (J. Clin. Oncol. 2013;31:2654-61).

The genes showing the greatest upregulation were those for pro-melanin–concentrating hormone (PMCH); ETS translocation variant 1 (ETV1); and tumor necrosis factor receptor superfamily, member 9 (TNFRSF9).

One of the genes showing greatest downregulation was the gene that encodes the cytoskeletal protein actinin (ACTN1), and the TILs indeed showed reduced motility when compared with the healthy T cells (P less than .025).

When cultured alone, healthy T cells did not express PMCH and had normal motility, but when cultured with follicular lymphoma cells, the T cells expressed this protein highly and had reduced motility (P = .0002).

The number of TILs expressing PMCH, ETV1, and NAMPT (nicotinamide phosphoribosyltransferase) and their locations in lymph nodes – in the malignant follicle (intrafollicular area), in the area between follicles (interfollicular area), and overall – as determined immunohistochemically, were significantly associated with both overall survival and time to transformation, the investigators said.

In multivariate analyses, the combination of the interfollicular-to-intrafollicular ratio of PMCH-expressing cells plus a high level of expression of NAMPT and a low level of expression of ETV1 in the intrafollicular area was the strongest predictor of longer time to transformation (hazard ratio, 0.19; P = .003).

Similarly, the combination of the number of PMCH- and NAMPT-expressing cells in the interfollicular area plus the interfollicular-to-intrafollicular ratio of ETV1 cells was the strongest predictor of better overall survival (hazard ratio, 0.32; P = .007).

The study was supported by grants from Cancer Research UK and the National Cancer Institute. One of the investigators disclosed receiving honoraria from Roche/Genentech and Celgene.

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A dual approach to B cells is needed

The findings of the study by Dr. Kiaii and his colleagues are particularly important as novel T-cell–mediated therapies are being developed for B-cell malignancies.

Lymphoma cells often induce immune tolerance by deleting or inactivating tumor-specific T cells. One attempt at overcoming this phenomenon has been chimeric antigen receptor (CAR) therapy; however, best results have been restricted to patients who had a low tumor burden and received cytotoxic chemotherapy beforehand.

The chemotherapy administered was likely to have not only depleted malignant cells but also decreased immunosuppressive cells. ... Malignant B cells, and the immunosuppressive tumor microenvironment they promote, may therefore remain a barrier to effective adoptive immunotherapy in B-cell lymphoma, particularly in patients with chemotherapy-resistant, bulky disease.

The data presented confirm that malignant B cells promote a profoundly immunosuppressive microenvironment and thereby protect themselves from being targeted by the immune system.

Future therapies in follicular lymphoma, including immunotherapies such as CAR T cells, will need to not only deplete malignant B cells but also inhibit the immunosuppressive mechanisms by which malignant B cells suppress the antitumor immune response. A dual approach that both depletes malignant cells and promotes immune function may subsequently result in a better clinical outcome for patients with follicular lymphoma.

Dr. Stephen M. Ansell is professor of medicine at the Mayo Clinic in Rochester, Minn. He made his remarks in an accompanying editorial (J. Clin. Oncol. 2013;31:2641-2). Dr. Ansell disclosed having no relevant conflicts of interest.