The Role of Tumor-Infiltrating Lymphocytes in Development, Progression, and Prognosis of Non-Small Cell Lung Cancer

A malignant tumor is not merely an accumulation of neoplastic cells, but constitutes a microenvironment containing endothelial cells, fibroblasts, structural components, and infiltrating immune cells that impact tumor development, invasion, metastasis, and outcome. Hence, the evolution of cancers reflects intricate cellular and molecular interactions between tumor cells and constituents of the tumor microenvironment. Recent studies have shed new light on this complex interaction between tumor and host immune cells and the resulting immune response. The composition of the immune microenvironment differs across patients as well as in cancers of the same type, including various populations of T cells, B cells, dendritic cells, natural killer cells, myeloid-derived suppressor cells, neutrophils, and macrophages. The type, density, location, and organization of immune cells within solid tumors define the immune contexture, which has proved to be a major determinant of tumor characteristics and patient outcome. Lung cancer consists mostly of non-small cell lung cancer (85%); it is our most deadly malignant disease, with the 5-year survival rate being merely 15%. This review focuses on the immune contexture; the tumor-suppressing roles of tumor-infiltrating lymphocytes; and the relevance of this immune contexture for cancer diagnostics, prognostication, and treatment allocation, with an emphasis on non-small cell lung cancer.

Targeted therapies and immune checkpoint inhibitors in the treatment of metastatic melanoma patients: a guide and update for pathologists

The previously dismal prospects for patients with advanced stage metastatic melanoma have greatly improved in recent years. Enhanced understanding of both the pathogenesis of melanoma and its molecular drivers, as well as the importance and regulation of anti-tumour immune responses, have provided new therapeutic opportunities for melanoma patients. There are two major distinct categories of systemic treatments with activity for patients with metastatic melanoma: (1) targeted therapies, which act to inhibit the oncogenes that drive the aberrant growth and dissemination of the tumour; and (2) immune checkpoint inhibitor therapies, which act to enhance anti-tumour immune responses by blocking negative regulators of immunity. Pathologists play a critical and expanding role in the selection of the most appropriate treatment for individual metastatic melanoma patients in the modern era of personalised/precision medicine. The molecular pathology testing of melanoma tumour tissue for the presence of targetable oncogenic mutations is already part of routine practice in many institutions. In addition, other potential oncogenic therapeutic targets continue to be identified and pathology testing techniques must readily adapt to this rapidly changing field. Recent research findings suggest that pathological assessment of tumour associated immune cells and immunosuppressive ligand expression of the tumour are likely to be important in identifying patients most likely to benefit from immune checkpoint inhibitors. Similarly, pathological and molecular observations of on-treatment tumour tissue biopsies taken from patients on targeted therapies have provided new insights into the mechanisms of action of targeted molecular therapies, have contributed to the identification of resistance mechanisms to these novel therapies and may be of higher value for selecting patients most likely to benefit from therapies. These data have already provided a rational biological basis for the exciting prospect of combining them to further improve survival rates and this is currently being investigated in clinical trials. Ultimately it may be the responsibility of the pathologist to identify which therapy or combination of therapies is most likely to benefit individual patients.

Potential biomarker for checkpoint blockade immunotherapy and treatment strategy

Programmed cell death protein-1 (PD-1) and ligand (PD-L1) provide an important escape mechanism from immune attack, and blockade therapy of these proteins show promising clinical benefits in many types of cancer. PD-L1 can be induced by interferon-gamma (IFN-γ), hypoxia, or toll-like receptor (TLR)-mediated pathways that confer adaptive immune resistance, or upregulated by oncogenic signals leading to constitutive expression and resulting in intrinsic immune resistance. The PD-1/PD-L1 checkpoint blockade, which targets regulatory pathways in T cells to overcome immune resistance, is correlated to PD-L1 expression pattern and the presence of tumor-infiltrating lymphocytes (TILs). Meanwhile, immunogenic mutation loads show significant response to checkpoint blockade, which is probably due to PD-1/L1 status and TIL content. Finally, the clinical strategies to design effective checkpoint-targeting immunotherapies are based on the classification of inducible/constitutive expression of PD-L1 and the presence of TILs.

How anti-PD1 treatments are changing the management of melanoma

The introduction of immunotherapy based on the blockade of the PD1/PD-L1 checkpoints has been associated with high response rates and durable remissions of disease in patients with metastatic melanoma, to the extent that it is now considered the standard of care for a wide range of patients, irrespective of their BRAF or NRAS mutation status. In addition, more frequent follow-up of patients who are at high risk of recurrence after surgical treatment appears to be justified, as does neoadjuvant treatments in order to render patients treatable by surgery. The limitations of this treatment include failure of some patients to respond, a low rate of complete responses and relapses of the disease during treatment. New initiatives in order to overcome these limitations include the identification of biomarkers for the selection responders and evaluations of treatment combinations that will increase responses and their durability. The latter includes combinations with antibodies against other checkpoints on T cells and cotreatments with inhibitors of resistance pathways in melanoma.

Immune correlates of melanoma survival in adoptive cell therapy

The advent of immunotherapies for cancer has resulted in robust clinical responses and confirmed that the immune system can significantly inhibit tumor progression. The recent success of adoptive cell therapy against melanoma suggests that endogenous T-cell responses have the potential to control cancer. However, the lack of responses in some patients receiving such therapy indicates a need for a better understanding of the host immune response to solid tumors. In this review, we summarize the current knowledge on the characteristics of adoptively transferred T cells associated with successful anti-melanoma immune responses in humans.

Targeting programmed cell death ligand 1 in osteosarcoma: an auto-commentary on therapeutic potential

Programmed cell death ligand 1 (PDL1) expression was recently shown to correlate with tumor-infiltrating lymphocytes (TILs) in a subset of osteosarcoma patients. Among clinical factors evaluated across human osteosarcoma samples, a pulmonary origin of metastases correlated with high PDL1 expression and prominent TILs. Considering that multiple agents targeting PD-1/PDL1 are under development, targeting this immune checkpoint may be a novel immunotherapeutic route for osteosarcoma in future clinical trials.

Tumor infiltrating lymphocytes are prognostic in triple negative breast cancer and predictive for trastuzumab benefit in early breast cancer: results from the FinHER trial

BACKGROUND

We have previously shown the prognostic importance of tumor-infiltrating lymphocytes (TILs) in newly diagnosed triple-negative breast cancer (TNBC) using tumor samples from a large clinical trial cohort. In this study, we aimed to validate these findings and also investigate associations with trastuzumab benefit in HER2-overexpressing disease (HER2+).

PATIENTS AND METHODS

A prospective-retrospective study was conducted using samples from the FinHER adjuvant, phase III trial that enrolled 1010 early-stage BC patients, 778 of whom were HER2-nonamplified. Those with HER2+ disease (n = 232) were randomized to 9 weeks of trastuzumab or no trastuzumab in addition to chemotherapy. Two pathologists independently quantified stromal TILs in 935 (92.6%) available slides. The primary end point of distant disease-free survival (DDFS) and interactions with trastuzumab were studied in Cox regression models.

RESULTS

Confirming our previous findings, in TNBC (n = 134) each 10% increase in TILs was significantly associated with decreased distant recurrence in TNBC; for DDFS the hazard ratio adjusted for clinicopathological factors: 0.77; 95% confidence interval (CI) 0.61-0.98, P = 0.02. In HER2+ BC (n = 209), each 10% increase in lymphocytic infiltration was significantly associated with decreased distant recurrence in patients randomized to the trastuzumab arm (DDFS P interaction = 0.025).

CONCLUSIONS

Higher levels of TILs present at diagnosis were significantly associated with decreased distant recurrence rates in primary TNBC. These results confirm our previous data and further support that TILs should be considered as a robust prognostic factor in this BC subtype. We also report for the first time an association between higher levels of TILs and increased trastuzumab benefit in HER2+ disease. Further research into why some TN and HER2+ BCs can or cannot generate a host antitumor immune response and how trastuzumab can favorably alter the immune microenvironment is warranted.

BRAF inhibition is associated with increased clonality in tumor-infiltrating lymphocytes

There have been significant advances with regard to BRAF-targeted therapies against metastatic melanoma. However, the majority of patients receiving BRAF inhibitors (BRAFi) manifest disease progression within a year. We have recently shown that melanoma patients treated with BRAFi exhibit an increase in melanoma-associated antigens and in CD8+ tumor-infiltrating lymphocytes in response to therapy. To characterize such a T-cell infiltrate, we analyzed the complementarity-determining region 3 (CDR3) of rearranged T-cell receptor (TCR) β chain-coding genes in tumor biopsies obtained before the initiation of BRAFi and 10-14 d later. We observed an increase in the clonality of tumor-infiltrating lymphocytes in 7 of 8 patients receiving BRAFi, with a statistically significant 21% aggregate increase in clonality. Over 80% of individual T-cell clones detected after initiation of BRAFi treatment were new clones. Interestingly, the comparison of tumor infiltrates with clinical responses revealed that patients who had a high proportion of pre-existing dominant clones after the administration of BRAFi responded better to therapy than patients who had a low proportion of such pre-existing dominant clones following BRAFi. These data suggest that although the inhibition of BRAF in melanoma patients results in tumor infiltration by new lymphocytes, the response to treatment appears to be related to the presence of a pre-existing population of tumor-infiltrating T-cell clones.

Imaging aspects of the tumor stroma with therapeutic implications

Cancer cells rely on extensive support from the stroma in order to survive, proliferate and invade. The tumor stroma is thus an important potential target for anti-cancer therapy. Typical changes in the stroma include a shift from the quiescence promoting-antiangiogenic extracellular matrix to a provisional matrix that promotes invasion and angiogenesis. These changes in the extracellular matrix are induced by changes in the secretion of extracellular matrix proteins and glucose amino glycans, extravasation of plasma proteins from hyperpermeable vessels and release of matrix modifying enzymes resulting in cleavage and cross-linking of matrix macromolecules. These in turn alter the rigidity of the matrix and the exposure and release of cytokines. Changes in matrix rigidity and vessel permeability affect drug delivery and mediate resistance to cytotoxic therapy. These stroma changes are brought about not only by the cancer cells, but also through the action of many cell types that are recruited by tumors including immune cells, fibroblasts and endothelial cells. Within the tumor, these normal host cells are activated resulting in loss of inhibitory and induction of cancer promoting activities. Key to the development of stroma-targeted therapies, selective biomarkers were developed for specific imaging of key aspects of the tumor stroma.

Anti-tumor effects of inactivated Sendai virus particles with an IL-2 gene on angiosarcoma

Cutaneous angiosarcoma is a life-threatening tumor that is resistant to conventional therapies. The therapeutic effects of Sendai virus particles (hemagglutinating virus of Japan envelope: HVJ-E) carrying IL-2 gene (HVJ-E/IL-2) were examined in a mouse model of angiosarcoma. Intra-tumoral injection of HVJ-E/IL-2 effectively inhibited the growth of angiosarcoma cells (ISOS-1) inoculated in mice and improved tumor-free rates. HVJ-E/IL-2 stimulated local accumulation of CD8 (+) T cells and NK cells and reduced regulatory T cells in regional lymph nodes. Notably, the prevalence of myeloid-derived suppressor cells was lower in HVJ-E/IL-2-treated mice than in HVJ-E-treated mice. HVJ-E/IL-2 treatment promoted IFN-γ production from CD8 (+) T cells in response to tumor cells, more significantly than HVJ-E treatment. Greatly improved tumor-free rates were obtained when sunitinib, a tyrosine kinase inhibitor, was administered in combination with HVJ-E/IL-2. Immunogene therapy with HVJ-E/IL-2 with or without sunitinib could be a promising therapeutic option for cutaneous angiosarcoma.