Neoadjuvant immunotherapy enhances radiosensitivity through natural killer cell activation

A Review of the Effects of Cervical Cancer Standard Treatment on Immune Parameters in Peripheral Blood, Tumor Draining Lymph Nodes, and Local Tumor Microenvironment

Cervical cancer remains a public health concern despite all the efforts to implement vaccination and screening programs. Conventional treatment for locally advanced cervical cancer consists of surgery, radiotherapy (with concurrent brachytherapy), combined with chemotherapy, or hyperthermia. The response rate to combination approaches involving immunomodulatory agents and conventional treatment modalities have been explored but remain dismal in patients with locally advanced disease. Studies exploring the immunological effects exerted by combination treatment modalities at the different levels of the immune system (peripheral blood (PB), tumor-draining lymph nodes (TDLN), and the local tumor microenvironment (TME)) are scarce. In this systemic review, we aim to define immunomodulatory and immunosuppressive effects induced by conventional treatment in cervical cancer patients to identify the optimal time point for immunotherapy administration. Radiotherapy (RT) and chemoradiation (CRT) induce an immunosuppressive state characterized by a long-lasting reduction in peripheral CD3, CD4, CD8 T cells and NK cells. At the TDLN level, CRT induced a reduction in Nrp1+Treg stability and number, naïve CD4 and CD8 T cell numbers, and an accompanying increase in IFNγ-producing CD4 helper T cells, CD8 T cells, and NK cells. Potentiation of the T-cell anti-tumor response was particularly observed in patients receiving low irradiation dosage. At the level of the TME, CRT induced a rebound effect characterized by a reduction of the T-cell anti-tumor response followed by stable radioresistant OX40 and FoxP3 Treg cell numbers. However, the effects induced by CRT were very heterogeneous across studies. Neoadjuvant chemotherapy (NACT) containing both paclitaxel and cisplatin induced a reduction in stromal FoxP3 Treg numbers and an increase in stromal and intratumoral CD8 T cells. Both CRT and NACT induced an increase in PD-L1 expression. Although there was no association between pre-treatment PD-L1 expression and treatment outcome, the data hint at an association with pro-inflammatory immune signatures, overall and disease-specific survival (OS, DSS). When considering NACT, we propose that posterior immunotherapy might further reduce immunosuppression and chemoresistance. This review points at differential effects induced by conventional treatment modalities at different immune compartments, thus, the compartmentalization of the immune responses as well as individual patient's treatment plans should be carefully considered when designing immunotherapy treatment regimens.

Comparison of Radiation With or Without Concurrent Trastuzumab for HER2-Positive Ductal Carcinoma In Situ Resected by Lumpectomy: A Phase III Clinical Trial

PURPOSE

Preclinical studies report that trastuzumab (T) can boost radiotherapy (RT) effectiveness. The primary aim of the B-43 trial was to assess the efficacy of RT alone vs concurrent RT plus T in preventing recurrence of ipsilateral breast cancer (IBTR) in women with ductal carcinoma in situ (DCIS).

PATIENTS AND METHODS

Eligibility: Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1, DCIS resected by lumpectomy, known estrogen receptor (ER) and/or progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) status by centralized testing. Whole-breast RT was given concurrently with T. Stratification was by menopausal status, adjuvant endocrine therapy plan, and nuclear grade. Definitive intent-to-treat primary analysis was to be conducted when either 163 IBTR events occurred or all accrued patients were on study ≥ 5 years.

RESULTS

There were 2,014 participants who were randomly assigned. Median follow-up time as of December 31, 2019, was 79.2 months. At primary definitive analysis, 114 IBTR events occurred: RT arm, 63 and RT plus T arm, 51 (hazard ratio [HR], 0.81; 95% CI, 0.56 to 1.17; P value = .26). There were 34 who were invasive: RT arm, 18 and RT plus T arm, 20 (HR, 1.11; 95% CI, 0.59 to 2.10; P value = .71). Seventy-six were DCIS: RT arm, 45 and RT plus T arm, 31 (HR, 0.68; 95% CI, 0.43 to 1.08; P value = .11). Annual IBTR event rates were: RT arm, 0.99%/y and RT plus T arm, 0.79%/y. The study did not reach the 163 protocol-specified events, so the definitive analysis was triggered by all patients having been on study for ≥ 5 years.

CONCLUSION

Addition of T to RT did not achieve the objective of 36% reduction in IBTR rate but did achieve a modest but statistically nonsignificant reduction of 19%. Nonetheless, this trial had negative results. Further exploration of RT plus T is needed in HER2-positive DCIS before its routine delivery in patients with DCIS resected by lumpectomy.

HER2 as a limited predictor of the therapeutic response to neoadjuvant therapy in locally advanced rectal cancer

Human epidermal growth factor 2 (HER2) is a candidate therapeutic and prognostic marker for rectal cancer treated with neoadjuvant chemoradiotherapy. The specific frequency and prognostic role of HER2 protein expression and HER2 gene amplification in those rectal cancers has not been fully investigated. Pretreatment biopsied and surgically resected formalin-fixed paraffin-embedded tissues from 74 patients were retrospectively evaluated for HER2 protein expression and HER2 gene copy number using immunohistochemistry (IHC) and silver in situ hybridization (SISH), respectively. The tumor response to chemoradiation was evaluated with TNM staging and tumor regression grading (TRG) systems. Good response to chemoradiation therapy (TRG3), poor response (22 TRG1 and 19 TRG2), and TNM downstaging achieved in 33 (44.6%), 41 (55.4%), and 42 (56.8%) patients, respectively. The frequency of HER2 positivity is 17.6%, all of which were low-level HER2 gene amplification with 2.2 of median gene copy number ratio, detected in IHC0 (3/39), IHC1+ (2/18), IHC2+ (5/14) and IHC3+ (2/3). There was no association of HER2 positivity with clinicopathological parameters or survival. However, older age (≥61 years) and HER2 positivity were the independent predictive factors for non-down staging, while poorly differentiation and the papillary pattern were predictors for poor response. In multivariate analysis, good response proved as an only independent favorable prognostic factor affecting survivals. In conclusion, HER2 positivity may be predictive for a high-risk therapeutic resistance in rectal cancers. The discrepancy between IHC and gene amplification may result from the low-level amplification, which may explain lack of prognostic impact of HER2 positivity.

Radiotherapy in the age of cancer immunology: Current concepts and future developments

Major advances in the knowledge of cancer biology and its interactions with tumor immune environment led to the emergence, in the last five years of new immunotherapy-based treatment strategies in cancer patients. At the same time, improvement in radiation technique and progress in radiobiology allowed in the last decade to expand the applications of radiotherapy in a growing number of settings. At present, there are strong theoretical basis to propose immune-enhanced radiation therapy that may represent in the future a new paradigm of treatment, combining the intrinsic power of radiotherapy to elicit a specific, systemic, tumor-directed immune response with modern highly conformal and precise dose delivery, in order to maximize response at the major site of disease and obtain durable disease control. The aim of this review is to describe the principal mechanisms of immune modulation of response to radiation and investigational strategies to harness the potential of radiation-inducible immune response: radiation therapy is expected to be not just a local treatment but the cornerstone of a multimodal strategy that might achieve long-lasting tumor remission at the primary site and systemic efficacy metastatic lesions.

Irradiation of breast cancer cells enhances CXCL16 ligand expression and induces the migration of natural killer cells expressing the CXCR6 receptor

BACKGROUND AIMS

Few studies have examined the migration pattern of natural killer (NK) cells, especially after radiation treatment for cancer. We investigated whether irradiation can modulate the expression of chemokines in cancer cells and the migration of NK cells to irradiated tumor cells.

METHODS

The expression of chemokine receptors (CXCR3, CXCR4 and CXCR6) on interleukin-2 (IL-2)/IL-15-activated NK cells was assessed using flow cytometry. Related chemokine ligands (CXCL11, CXCL12 and CXCL16) in human breast cancer cell lines (MCF7, SKBR3 and MDA-MB231) irradiated at various doses were assessed using reverse transcription-polymerase chain reaction (RT-PCR), fluorescence-activated cell sorting (FACS) and enzyme-linked immunosorbent assay (ELISA). The cell-free culture supernatant was collected 96 h after irradiation of breast cancer cell lines for migration and blocking assays.

RESULTS

The activated NK cells expressed CXCR6. Expression of the CXCR6 ligand CXCL16 increased in a time- and dose-dependent manner in all analyzed cancer cell lines. CXCL16 expression was statistically significantly enhanced in all breast cancer cell lines on day 3 after 20 Gy irradiation. Activated NK cells migration correlated with CXCL16 concentration (R² = 0.91; P <0.0001). Significantly enhanced migration of NK cells to irradiated cancer cells was observed for a dose of 20 Gy in MCF7 (P = 0.043) and SKBR3 (P = 0.043) cells, but not in MDA-MB231 (P = 0.225) cells. A blocking assay using a CXCR6 antibody showed a significant decrease in the migration of activated NK cells in all cancer cell lines.

CONCLUSIONS

Our data indicate that irradiation induces CXCL16 chemokine expression in cancer cells and enhances the migration of activated NK cells expressing CXCR6 to irradiated breast cancer cells. These results suggest that radiation would improve the anti-tumor effect of NK cells through enhanced migration of NK cells to tumor site for the treatment of patients with breast cancer.

The peripheral myeloid expansion driven by murine cancer progression is reversed by radiation therapy of the tumor

Expansion of myeloid-lineage leukocytes in tumor-bearing mice has been proposed as a cause of systemic immunosuppression. We demonstrate that radiation therapy of tumors leads to a decline in myeloid cell numbers in the blood and a decrease in spleen size. The frequency of myeloid cells does not decline to the level seen in tumor-free mice: we demonstrate that metastatic disease can prevent myeloid cell numbers from returning to baseline, and that tumor recurrence from residual disease correlates with re-expansion of myeloid lineage cells. Radiation therapy results in increased proliferation of T cells in the spleen and while T cell responses to foreign antigens are not altered by tumor burden or myeloid cell expansion, responses to tumor-associated antigens are increased after radiation therapy. These data demonstrate that myeloid cell numbers are directly linked to primary tumor burden, that this population contracts following radiation therapy, and that radiation therapy may open a therapeutic window for immunotherapy of residual disease.

Reciprocal complementation of the tumoricidal effects of radiation and natural killer cells

The tumor microenvironment is a key determinant for radio-responsiveness. Immune cells play an important role in shaping tumor microenvironments; however, there is limited understanding of how natural killer (NK) cells can enhance radiation effects. This study aimed to assess the mechanism of reciprocal complementation of radiation and NK cells on tumor killing. Various tumor cell lines were co-cultured with human primary NK cells or NK cell line (NK-92) for short periods and then exposed to irradiation. Cell proliferation, apoptosis and transwell assays were performed to assess apoptotic efficacy and cell viability. Western blot analysis and immunoprecipitation methods were used to determine XIAP (X-linked inhibitor of apoptosis protein) and Smac (second mitochondria-derived activator of caspase) expression and interaction in tumor cells. Co-culture did not induce apoptosis in tumor cells, but a time- and dose-dependent enhancing effect was found when co-cultured cells were irradiated. A key role for caspase activation via perforin/granzyme B (Grz B) after cell-cell contact was determined, as the primary radiation enhancing effect. The efficacy of NK cell killing was attenuated by upregulation of XIAP to bind caspase-3 in tumor cells to escape apoptosis. Knockdown of XIAP effectively potentiated NK cell-mediated apoptosis. Radiation induced Smac released from mitochondria and neutralized XIAP and therefore increased the NK killing. Our findings suggest NK cells in tumor microenvironment have direct radiosensitization effect through Grz B injection while radiation enhances NK cytotoxicity through triggering Smac release.

Immune Cells in Colorectal Cancer: Prognostic Relevance and Role of MSI

There is growing evidence that both local and systemic inflammatory responses play an important role in the progression of a variety of solid tumors. Colorectal cancer (CRC) results from the cumulative effect of sequential genetic alterations, leading to the expression of tumor-associated antigens possibly inducing a cellular anti-tumor immune response. It is well recognized that cytotoxic lymphocytes (CTLs) constitute one of the most important effector mechanisms of anti-tumor-immunity. However, their potential prognostic influence in CRC remains controversial. In addition, other key players like natural killer cells, tumor associated macrophages and regulatory T cells play an important role in the immune attack against CRC and need further investigation. This review will mainly focus on the role of the adaptive immune system in CRC and particularly in regard to microsatellite instability.