The role of B cells in the tumor microenvironment and B-cell-mediated antitumor immune responses remains relatively understudied. Recent seminal studies have discovered that B cells and associated tertiary lymphoid structures correlate with responses to checkpoint blockade immunotherapy and are prognostic for overall survival of cancer patients. B-cell subsets have remarkable functional diversity and include professional antigen-presenting cells, regulatory cells, memory populations, and antibody-producing plasma cells. Importantly, secreted antibodies can independently activate innate immune responses and induce the cancer immunity cycle. Thus, B cells and B-cell-mediated antibody responses comprise the largely underappreciated second arm of the adaptive immune system and certainly deserve further attention in the field of oncology. Here, we review the known functions of B cells in the tumor microenvironment, the contribution of B cells to the antitumor activity of immunotherapies, and the role of B cells in the overall survival of cancer patients.

This patient was found to have a scirrhous carcinoma with extensive perineural invasion and without any evidence of minor salivary gland carcinoma. To our knowledge, this is the first report of isolated scirrhous carcinoma of the oral cavity. Treatment was surgery and adjuvant chemoradiation, and there was complete disease response.

Radiation therapy exerts a tumoricidal local effect as well as both local and systemic immunomodulation. Immune checkpoint blockade has become a widely used treatment modality across cancer types with a rapidly growing list of agents and US Food and Drug Administration-approved indications. Moreover, there may be synergy between radiation therapy and immune checkpoint blockade. Various strategies have been used, but the optimal sequencing of these therapies is unclear. In this review, the authors discuss the major mechanisms of available immune checkpoint inhibitors and explore the available preclinical and clinical evidence regarding treatment sequencing. They also review safety considerations and conclude with possible future directions.

Background

Image guidance in radiation oncology has resulted in significant improvements in the accuracy and precision of radiation therapy (RT). Recently, the resolution and quality of cone beam computed tomography (CBCT) for image guidance has increased so that tumor masses and lymph nodes are readily detectable and measurable. During treatment of head and neck squamous cell carcinoma (HNSCC), on-board CBCT setup imaging is routinely obtained; however, this CBCT imaging data is not utilized to predict patient outcomes. Here, we analyzed whether changes in CBCT measurements obtained during a course of radiation therapy correlate with responses on routine 3-month follow-up diagnostic imaging and overall survival (OS).

Materials/methods

Patients with oropharyngeal primary tumors who received radiation therapy between 2015 and 2018 were included. Anatomical measurements were collected of largest nodal conglomerate (LNC) at CT simulation, end of radiation treatment (EOT CBCT), and routine 3-month post-RT imaging. At each timepoint anteroposterior (AP), mediolateral (ML) and craniocaudal (CC) measurements were obtained and used to create a 2-dimensional (2D) maximum.

Results

CBCT data from 64 node positive patients were analyzed. The largest nodal 2D maximum and CC measurements on EOT CBCT showed a statistically significant correlation with complete response on 3-month post-RT imaging (r = 0.313, p = 0.02 and r = 0.318, p = 0.02, respectively). Furthermore, patients who experienced a 30% or greater reduction in the CC dimension had improved OS (Binary Chi-Square HR 4.85, p = 0.028).

Conclusion

Decreased size of pathologic lymph nodes measured using CBCT setup imaging during a radiation course correlates with long term therapeutic response and overall survival of HNSCC patients. These results indicate that CBCT setup imaging may have utility as an early predictor of treatment response in oropharyngeal HNSCC.

Background: Undifferentiated pleomorphic sarcoma (UPS) of the maxillary sinus is an extremely rare malignancy of the head and neck. Surgery is the mainstay of treatment for UPS; however, proximity to vital structures makes it challenging to achieve negative surgical margins. Adjuvant therapy including radiation therapy with or without chemotherapy is generally indicated. Despite advances in multimodality treatment, objective response rates to available therapies and prognosis of metastatic UPS remain dismal. Immunotherapy has become a fourth cornerstone of cancer therapy and checkpoint blockade immunotherapy is a standard of care for recurrent or metastatic cisplatin-refractory head and neck squamous cell carcinoma. Checkpoint blockade immunotherapy is being studied in metastatic sarcoma, including UPS, and while initial results are promising, objective response rates remain below 20%. However, adding radiation therapy to checkpoint blockade immunotherapy has been shown, in both preclinical and retrospective clinical studies, to have combinatorial effects on both local and metastatic disease. Thus, further investigation into the effects of radiation therapy combined with immunotherapy in head and neck sarcomas is warranted. Case Presentation: We present a case of metastatic, chemotherapy-refractory, UPS of the maxillary sinus in a 55-year-old male treated with checkpoint blockade immunotherapy combined with radiation, which resulted in a complete response. Conclusions: This is the first report to our knowledge of metastatic UPS treated with a combination of radiation and dual agent checkpoint blockade immunotherapy. Further investigation is warranted to study the effects of this combination in patients with metastatic UPS that fail to respond to currently available therapies.

Purpose

To characterize the role of B cells on human papilloma virus (HPV)-associated cancer patient outcomes and determine the effects of radiation and PD-1 blockade on B-cell populations.

Experimental design

Tumor RNA-sequencing data from over 800 patients with head and neck squamous cell carcinoma (HNSCC) and cervical cancer, including a prospective validation cohort, was analyzed to study the impact of B-cell gene expression on overall survival (OS). A novel murine model of HPV⁺ HNSCC was used to study the effects of PD-1 blockade and radiotherapy on B-cell activation, differentiation, and clonality including analysis by single-cell RNA-sequencing and B-cell receptor (BCR)-sequencing. Human protein microarray was then used to quantify B-cell-mediated IgG and IgM antibodies to over 16,000 proteins in the serum of patients treated on a clinical trial with PD-1 blockade.

Results

RNA-sequencing identified CD19 and IGJ as novel B-cell prognostic biomarkers for 3-year OS (HR, 0.545; P < 0.001). PD-1 blockade and radiotherapy enhance development of memory B cells, plasma cells, and antigen-specific B cells. BCR-sequencing found that radiotherapy enhances B-cell clonality, decreases CDR3 length, and induces B-cell somatic hypermutation. Single-cell RNA-sequencing identified dramatic increases in B-cell germinal center formation after PD-1 blockade and radiotherapy. Human proteome array revealed enhanced IgG and IgM antibody responses in patients who derived clinical benefit but not those with progressive disease after treatment with PD-1 blockade.

Conclusions

These findings establish a key role for B cells in patient outcomes and responses to PD-1 blockade in HPV-associated squamous cell carcinomas and demonstrate the need for additional diagnostics and therapeutics targeting B cells.

Purpose

B cells play a key role in outcomes of cancer patients and responses to checkpoint blockade immunotherapies. However, the effect of radiation therapy on B cell populations is poorly understood. Here we characterize the effects of radiation on the development, survival, and phenotype of physiological B-cell subsets.

Methods and materials

Naïve and immunized tumor bearing and nontumor bearing mice were treated with large-field or focal stereotactic radiation and distinct B-cell subsets of varying developmental stages were analyzed by flow cytometry and real-time reverse transcription polymerase chain reaction.

Results

We first report that focal stereotactic radiation is highly superior to large-field radiation at inducing tumor infiltration of B cells, CD8⁺ T cells, and macrophages. We observed that radiation affects B cell development in the bone marrow, increasing frequencies of early pro-B cells and late pro-B cells while inducing upregulation of programmed cell death protein 1. We then demonstrate that class switched B cells and plasma cells are highly resistant to radiation therapy compared with naïve B cells and upregulate activation markers programmed cell death 1 ligand 2 and major histocompatibility complex class II) after radiation. Mechanistically, radiation upregulates Xbp1 and Bcl6 in plasma cells, conferring radioresistance. Furthermore, using an immunization approach, we demonstrate that radiation enhances activation-induced cytidine deaminase mediated class switching and somatic hypermutation in primed B cells.

Conclusions

These data demonstrate that stereotactic radiation is superior to large-field radiation at inducing infiltration of immune cells into tumors and that plasma cells and class switched B cells are highly resistant to radiation therapy. These results represent the most comprehensive analysis of the effects of radiation on B cells to date and identify novel mechanisms by which radiation modulates immune cells within the tumor microenvironment.

There is a critical need to understand mechanisms of resistance and to develop combinatorial strategies to improve responses to checkpoint blockade immunotherapy (CBI). Here, we uncover a novel mechanism by which the human papillomavirus (HPV) inhibits the activity of CBI in head and neck squamous cell carcinoma (HNSCC). Using orthotopic HNSCC models, we show that radiation combined with anti-PD-L1 immunotherapy significantly enhanced local control, CD8⁺ memory T cells, and induced preferential T-cell homing via modulation of vascular endothelial cells. However, the HPV E5 oncoprotein suppressed immune responses by downregulating expression of major histocompatibility complex and interfering with antigen presentation in murine models and patient tumors. Furthermore, tumors expressing HPV E5 were rendered entirely resistant to anti-PD-L1 immunotherapy, and patients with high expression of HPV16 E5 had worse survival. The antiviral E5 inhibitor rimantadine demonstrated remarkable single-agent antitumor activity. This is the first report that describes HPV E5 as a mediator of resistance to anti-PD-1/PD-L1 immunotherapy and demonstrates the antitumor activity of rimantadine. These results have broad clinical relevance beyond HNSCC to other HPV-associated malignancies and reveal a powerful mechanism of HPV-mediated immunosuppression, which can be exploited to improve response rates to checkpoint blockade. SIGNIFICANCE: This study identifies a novel mechanism of resistance to anti-PD-1/PD-L1 immunotherapy mediated by HPV E5, which can be exploited using the HPV E5 inhibitor rimantadine to improve outcomes for head and neck cancer patients. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/4/732/F1.large.jpg.

Continued discoveries of negative regulators of inflammatory signaling provide detailed molecular insights into peripheral tolerance and anti-tumor immunity. Accumulating evidence indicates that peripheral tolerance is maintained at multiple levels of immune responses by negative regulators of proinflammatory signaling, soluble anti-inflammatory factors, inhibitory surface receptors & ligands, and regulatory cell subsets. This review provides a global overview of these regulatory machineries that work in concert to maintain peripheral tolerance at cellular and host levels, focusing on the direct and indirect regulation of T cells. The recent success of checkpoint blockade immunotherapy (CBI) has initiated a dramatic shift in the paradigm of cancer treatment. Unprecedented responses to CBI have highlighted the central role of T cells in both anti-tumor immunity and peripheral tolerance and underscored the importance of T cell exhaustion in cancer. We discuss the therapeutic implications of modulating the negative regulators of T cell function for tumor immunotherapy with an emphasis on inhibitory surface receptors & ligands-central players in T cell exhaustion and targets of checkpoint blockade immunotherapies. We then introduce a Threshold Model for Immune Activation-the concept that these regulatory mechanisms contribute to defining a set threshold of immunogenic (proinflammatory) signaling required to elicit an anti-tumor or autoimmune response. We demonstrate the value of the Threshold Model in understanding clinical responses and immune related adverse events in the context of peripheral tolerance, tumor immunity, and the era of Checkpoint Blockade Immunotherapy.

PURPOSE:To study the effects of immunosuppression on treatment toxicity, long-term cancer recurrence risk, and survival among human immunodeficiency virus (HIV)-positive anal cancer patients. METHODS AND MATERIALS:From a nationwide retrospective cohort of veterans with anal cancer we identified 142 HIV-positive patients with stage I-III disease, diagnosed between 2000 and 2015 and treated with definitive-intent chemotherapy and radiation. We used regression models to study the impact of pretreatment CD4 counts and longitudinal posttreatment CD4 counts on outcomes including acute toxicity, long-term ostomy rates, cancer recurrence, cancer-specific survival, and overall survival. All models were adjusted for potential confounders. RESULTS:The median pretreatment CD4 count was 375 cells/mm3, which dropped to 157 cells/mm3 after treatment. Each 100-cell/mm3 decrease in pretreatment CD4 count was associated with an increased risk of acute hematologic toxicity (odds ratio 1.19, 95% confidence interval [CI] 1.01-1.42, P=.04) and hospitalization for hematologic toxicity (odds ratio 1.24, 95% CI 1.00-1.54, P=.049) but not gastrointestinal toxicity, tumor recurrence, or cancer-specific mortality (P>.05). Each 100-cells/mm3 decrease in posttreatment CD4 count increased the risk of recurrence by 54% (hazard ratio 1.54, 95% CI 1.09-2.17, P=.01) and cancer mortality by 46% at a trend level (hazard ratio 1.46, 95% CI 0.99-2.14, P=.06). Neither pre- nor posttreatment CD4 count influenced long-term ostomy rates or overall survival (all P>.05). CONCLUSIONS:Lower pretreatment CD4 counts were associated with acute hematologic toxicity, and lower posttreatment CD4 count levels were associated with an increased risk of tumor recurrence. These results suggest that immune surveillance may play an important role in long-term disease control in anal cancer.