Tumor Eradication by Cisplatin Is Sustained by CD80/86-Mediated Costimulation of CD8+ T Cells

Cervical Cancer Immunotherapy: Facts and Hopes

It is a sad fact that despite being almost completely preventable through human papillomavirus (HPV) vaccination and screening, cervical cancer remains the fourth most common cancer to affect women worldwide. Persistent high-risk HPV (hrHPV) infection is the primary etiologic factor for cervical cancer. Upward of 70% of cases are driven by HPV types 16 and 18, with a dozen other hrHPVs associated with the remainder of cases. Current standard-of-care treatments include radiotherapy, chemotherapy, and/or surgical resection. However, they have significant side effects and limited efficacy against advanced disease. There are a few treatment options for recurrent or metastatic cases. Immunotherapy offers new hope, as demonstrated by the recent approval of programmed cell death protein 1-blocking antibody for recurrent or metastatic disease. This might be augmented by combination with antigen-specific immunotherapy approaches, such as vaccines or adoptive cell transfer, to enhance the host cellular immune response targeting HPV-positive cancer cells. As cervical cancer progresses, it can foster an immunosuppressive microenvironment and counteract host anticancer immunity. Thus, approaches to reverse suppressive immune environments and bolster effector T-cell functioning are likely to enhance the success of such cervical cancer immunotherapy. The success of nonspecific immunostimulants like imiquimod against genital warts also suggest the possibility of utilizing these immunotherapeutic strategies in cervical cancer prevention to treat precursor lesions (cervical intraepithelial neoplasia) and persistent hrHPV infections against which the licensed prophylactic HPV vaccines have no efficacy. Here, we review the progress and challenges in the development of immunotherapeutic approaches for the prevention and treatment of cervical cancer.

CD80 Expression on Tumor Cells Alters Tumor Microenvironment and Efficacy of Cancer Immunotherapy by CTLA-4 Blockade

Cluster of differentiation (CD) 80 is mainly expressed in immune cells but can also be found in several types of cancer cells. This molecule may either activate or inhibit immune reactions. Here, we determined the immunosuppressive role of CD80 in the tumor microenvironment by CRISPR/Cas9-mediated deactivation of the corresponding gene in the mouse oncogenic TC-1 cell line. The tumor cells with deactivated CD80 (TC-1/dCD80-1) were more immunogenic than parental cells and induced tumors that gained sensitivity to cytotoxic T-lymphocyte antigen 4 (CTLA-4) blockade, as compared with the TC-1 cells. In vivo depletion experiments showed that the deactivation of CD80 switched the pro-tumorigenic effect of macrophages observed in TC-1-induced tumors into an anti-tumorigenic effect in TC-1/dCD80-1 tumors and induced the pro-tumorigenic activity of CD4⁺ cells. Moreover, the frequency of lymphoid and myeloid cells and the CTLA-4 expression by T helper (Th)17 cells were increased in TC-1/dCD80-1- compared with that in the TC-1-induced tumors. CTLA-4 blockade downregulated the frequencies of most immune cell types and upregulated the frequency of M2 macrophages in the TC-1 tumors, while it increased the frequency of lymphoid cells in TC-1/dCD80-1-induced tumors. Furthermore, the anti-CTLA-4 therapy enhanced the frequency of CD8⁺ T cells as well as CD4⁺ T cells, especially for a Th1 subset. Regulatory T cells (Treg) formed the most abundant CD4⁺ T cell subset in untreated tumors. The anti-CTLA-4 treatment downregulated the frequency of Treg cells with limited immunosuppressive potential in the TC-1 tumors, whereas it enriched this type of Treg cells and decreased the Treg cells with high immunosuppressive potential in TC-1/dCD80-1-induced tumors. The immunosuppressive role of tumor-cell-expressed CD80 should be considered in research into biomarkers for the prediction of cancer patients' sensitivity to immune checkpoint inhibitors and for the development of a tumor-cell-specific CD80 blockade.

Cisplatin Loaded Poly(L-glutamic acid)-g-Methoxy Polyethylene Glycol Complex Nanoparticles Combined with Gemcitabine Presents Improved Safety and Lasting Anti-Tumor Efficacy in a Murine Xenograft Model of Human Aggressive B Cell Lymphoma

Cisplatin (CDDP) is a highly effective anti-tumor drug with a broad spectrum of activity. However, the clinical efficacy of CDDP-containing regimens is yet unsatisfactory due to the severe dose-related toxicity of CDDP. In a previous study, CDDP nanoparticles (L-CDDP) forms a complex as CDDP with poly(L-glutamic acid)-g-methoxy poly(ethylene glycol) with improved safety compared to CDDP. Herein, a murine xenograft model of human aggressive B cell lymphoma (BCL) was established to explore anti-lymphoma efficiency of L-CDDP combined with GEM. BJAB cells represent an aggressive BCL, which were utilized to explore the anti-proliferative effect, cell apoptosis via CCK-8 test and flow cytometry technology, respectively. Toxicity experiment and the maximum tolerated dose (MTD) test were conducted in Kunming mice. Tumor inhibition experiment was conducted at the dose of MTD in SCID beige mice-bearing lymphoma. In this study, the loading capacity and encapsulating efficiency of CDDP in the L-CDDP was 18.3% and 89.7%, respectively, and the hydrodynamic diameter of the prepared L-CDDP was 20.6 nm. The CCK-8 data indicated that the anti-proliferative activity of monodrug groups (GEM, CDDP, L-CDDP) was dose- and time-dependent in BJAB cells. The synergistic effects in anti-lymphoma were detected in these two groups (GEM+CDDP, GEM + L-CDDP). Compared to control group, the proportion of apoptotic cells in experimental groups in BJAB cells was significantly higher at 48 h. Toxicity assays revealed that GEM + L-CDDP regimen had low hematological toxicity, hepatotoxicity, and nephrotoxicity. Tumor inhibition experiment demonstrated that GEM + L-CDDP group exhibited significant tumor-suppressing effects. Moreover, tumors continued to shrink in GEM + L-CDDP group, while these appeared to grow in the GEM + CDDP group. Finally, tumor necrosis was most prominent in the GEM + CDDP and GEM + L-CDDP groups, as assessed by hematoxylin-eosin staining. In conclusion, compared to CDDP, L-CDDP combined with GEM seriously induces BJAB cell apoptosis. Also, GEM + L-CDDP exhibits low hematotoxicity, hepatotoxicity, and nephrotoxicity. Importantly, GEM + L-CDDP presents lasting anti-lymphoma efficacy in a SCID beige mice-bearing lymphoma.

Tumor microenvironment in head and neck squamous cell carcinoma: Functions and regulatory mechanisms

The tumor microenvironment has been recently reported to play a pivotal role in sustaining tumor cells survival and protecting them from immunotherapy and chemotherapy-induced death. It remains largely unknown how the specific signaling pathway exerts the tumor microenvironment in head and neck squamous cell carcinoma though previous studies have elucidated the regulatory mechanisms involve in tumor immune microenvironment, stromal cells, tumor angiogenesis and cancer stem cell. These components are responsible for tumor progression as well as anti-cancer therapy resistance, leading to rapid tumor growth and treatment failure. In this review, we focus on discussing the interaction between tumor cells and the surrounding components for better understanding of anti-cancer treatment ineffectiveness and its underlying molecular mechanisms.

Small cell lung cancer: a slightly less orphan disease after immunotherapy

Small cell lung cancer (SCLC) is an aggressive malignancy accounting for 15% of all diagnosed cases of lung cancer. After >15 years without any clinically relevant therapeutic advances, extensive-disease SCLC has become the second thoracic malignancy for which immune checkpoint inhibitors (ICIs) have shifted the treatment paradigm to improve overall survival. Today, atezolizumab or durvalumab in combination with platinum-etoposide chemotherapy is considered the new standard of care in the first-line setting in SCLC. However, the magnitude of benefit with this immune-chemotherapy strategy in SCLC is more modest than that observed in metastatic non-small-cell lung cancer patients. The immunosuppressive phenotype of SCLC plays an important role in hampering ICI efficacy and may explain the differences in outcomes between these two types of lung cancer. In this review, we provide a summary of recent therapeutic advances in SCLC in light of ICIs, as well as current challenges of this strategy in patients who are elderly, have poor performance status or brain metastases. We also address future perspectives of immunotherapeutic strategies currently in clinical development for these patients.

Improving Anti-PD-1/PD-L1 Therapy for Localized Bladder Cancer

In high-risk non-muscle invasive bladder cancer (HR-NMIBC), patient outcome is negatively affected by lack of response to Bacillus-Calmette Guérin (BCG) treatment. Lack of response to cisplatin-based neoadjuvant chemotherapy and cisplatin ineligibility reduces successful treatment outcomes in muscle-invasive bladder cancer (MIBC) patients. The effectiveness of PD-1/PD-L1 immune checkpoint inhibitors (ICI) in metastatic disease has stimulated its evaluation as a treatment option in HR-NMIBC and MIBC patients. However, the observed responses, immune-related adverse events and high costs associated with ICI have provided impetus for the development of methods to improve patient stratification, enhance anti-tumorigenic effects and reduce toxicity. Here, we review the challenges and opportunities offered by PD-1/PD-L1 inhibition in HR-NMIBC and MIBC. We highlight the gaps in the field that need to be addressed to improve patient outcome including biomarkers for response stratification and potentially synergistic combination therapy regimens with PD-1/PD-L1 blockade.

Therapies for tuberculosis and AIDS: myeloid-derived suppressor cells in focus

The critical role of suppressive myeloid cells in immune regulation has come to the forefront in cancer research, with myeloid-derived suppressor cells (MDSCs) as a main oncology immunotherapeutic target. Recent improvement and standardization of criteria classifying tumor-induced MDSCs have led to unified descriptions and also promoted MDSC research in tuberculosis (TB) and AIDS. Despite convincing evidence on the induction of MDSCs by pathogen-derived molecules and inflammatory mediators in TB and AIDS, very little attention has been given to their therapeutic modulation or roles in vaccination in these diseases. Clinical manifestations in TB are consequences of complex host-pathogen interactions and are substantially affected by HIV infection. Here we summarize the current understanding and knowledge gaps regarding the role of MDSCs in HIV and Mycobacterium tuberculosis (co)infections. We discuss key scientific priorities to enable application of this knowledge to the development of novel strategies to improve vaccine efficacy and/or implementation of enhanced treatment approaches. Building on recent findings and potential for cross-fertilization between oncology and infection biology, we highlight current challenges and untapped opportunities for translating new advances in MDSC research into clinical applications for TB and AIDS.

The Tumor Microenvironment and Immunotherapy of Oropharyngeal Squamous Cell Carcinoma

Oropharyngeal squamous cell carcinoma (OPSCC) develops as a consequence of several mutations in the tumor suppressor pathways or after a progressive infection with high risk human papillomavirus (HPV). The dismal side effects of the current standard of care and the clear involvement of the immune system has led to a surge in clinical trials that aim to reinforce the tumor-specific immune response as a new treatment option. In this review, we have focused on the most recent literature to discuss the new findings and insights on the role of different immune cells in the context of OPSCC and its etiology. We then applied this knowledge to describe potential biomarkers and analyzed the rationale and outcomes of earlier and ongoing immunotherapy trials. Finally, we describe new developments that are still at the preclinical phase and provide an outlook on what the near future may bring, now that several new and exciting techniques to study the immune system at the single cell level are being exploited.

Low-dose carboplatin reprograms tumor immune microenvironment through STING signaling pathway and synergizes with PD-1 inhibitors in lung cancer

Although the combination of chemotherapy and immunotherapy is a hot topic in lung cancer, little is understood regarding the possible mechanisms behind their synergy. Moreover, safety is a major concern for clinicians while performing chemotherapy. Therefore, it is important to determine the appropriate dose and period of chemotherapy for combining it with immunotherapy, and investigate the underlying synergistic mechanism. Here, we showed that carboplatin can induce DNA damage and activate the canonical STING/TBK1/IRF3 pathway and non-canonical STING-NF-κB signaling complex. Further, low-dose carboplatin changed the "cold" tumor into a "hot" tumor via the signaling hub STING, augmenting CD8⁺ T-cell infiltration, increasing PD-L1 expression, and hence potentiating the anti-tumor effect of PD-1 inhibitors; importantly, there were no adverse effects. Furthermore, knocking down STING in tumor cells effectively reversed PD-L1 upregulation and STING pathway activation, and reduced the anti-tumor effect of low-dose carboplatin and carboplatin-PD-1 inhibitor combination. Our findings collectively reported a previously unexplored role of low-dose carboplatin targeting in the STING pathway and provided an economical, useful and safe option for improving the efficacy of PD-1 inhibitors in lung cancer.

Ultrasound targeting of microbubble-bound anti PD-L1 mAb to enhance anti-tumor effect of cisplatin in cervical cancer xenografts treatment

AIMS

Anti-PD-L1 monoclonal antibody (mAb)-conjugated ultrasound (US) lipid-shelled microbubbles (PD-L1-MBs) were successfully synthesized to investigate whether that PD-L1-MBs could enhance anti-tumor effect in combination therapy with cisplatin (CDDP) under ultrasound mediation.

MAIN METHODS

Based on affinity between biotin and streptavidin, we prepared microbubbles conjugated with anti-PD-L1 mAb by membrane hydration and mechanical oscillation. A subcutaneous tumor model was established to test the anti-tumor effect and immunological activity of this combination therapy. Bax and Bcl-2 expression were detected by RT-qPCR and Immunohistochemistry. Cells undergoing apoptosis in tissue section were determined by TUNEL. Proliferation of splenocytes was analyzed by Flow cytometry. A cytotoxic T lymphocyte assay was performed by CTL. Expression of PD-L1 and CD8 in tissue section was examined by immunologfluorescence. Expression of IFN-γ, TNF-α, CD86 and CD80 was also detected by RT-qPCR.

KEY FINDINGS

We observed that the growth of the subcutaneous tumor was significantly slower in combined group than that in the group treated with either drug or microbubbles. Moreover, higher antitumor activity was observed in the combined group than that in cisplatin alone, which could be reflected by the number of apoptotic cells in tumor tissues and over expression of bax in the combined group. This combination treatment also exhibited a better immunological activity, increasing the infiltration of CD8⁺ T cells and the expression of several revelant cytokines.

SIGNIFICANCE

The ultrasound lipid-shelled PD-L1-MBs may enhance anti-tumor effects of cisplatin by blocking the PD-L1 site and improving immune function.

Platinum-based chemotherapy in combination with PD-1/PD-L1 inhibitors: preclinical and clinical studies and mechanism of action

INTRODUCTION

Platinum chemotherapy is widely used in first-line treatment of patients with various cancers. PD-1/PD-L1 inhibitors have shown efficacy in several cancers, and the combination of platinum-based chemotherapy and PD-1/PD-L1 inhibitors has gradually become the focus of attention. Recently, the combination therapy has exhibited significant effects in preclinical models and clinical trials.

AREAS COVERED

This review summarizes preclinical and clinical studies of the combination therapy in various cancers, and further explores mechanisms of the treatment. Furthermore, exploration of the mechanism demonstrates that the combination therapy plays a combination role in two ways. On the one hand, the positive effects of platinum-based chemotherapy on immunomodulation can be harnessed to increase the sensitivity of tumor cells to PD-1/PD-L1 inhibitors. On the other hand, platinum-based chemotherapy may upregulate PD-L1 expression in tumor tissue and exert a negative immunomodulatory effect, which can be counteracted by PD-1/PD-L1 inhibitors through their action pathway. What's more, different types of platinum-based chemotherapy exert different immunomodulation properties.

EXPERT OPINION

This review describes a potential for the combination of PD-1/PD-L1 inhibitors and novel nanoparticles composed of platinum-loaded complex to yield positive effects in a wide range of doses, thus achieving higher therapeutic effects and lower side effects.

ABBREVIATIONS

Treg: regulatory T cell; MDSC: myeloid-derived suppressor cell; TAM: tumor-associated macrophage; IL: interleukin; PD-1: programmed cell death protein-1; PD-L1: programmed death-ligand-1; NSCLC: non-small cell lung cancer; SCLC: small cell lung cancer; HNSCC: head and neck squamous cell cancer; ICD: immunogenic cell death; TME: tumor microenvironment; CTLs: cytotoxic T lymphocytes; TCR: T cell receptor; MHC class 1: major histocompatibility complex class 1; DC: dendritic cell; APC: antigen-presenting cell; PD-L2: programmed death-ligand-2; STAT6: signal transducers and activators of transcription 6; PLG: poly (L-glutamic acid); mPEG: methoxy poly (ethylene glycol); LLC1: Lewis lung carcinoma 1; PI3K: phosphoinositide 3-kinase; AKT: protein kinase B; MOC1: mouse oral cancer 1; cGAS: cyclic guanosine monophosphate-adenosine monophosphate synthase; STING: stimulator of interferon genes; FDA: food and drug administration; cHL: classical Hodgkin's lymphoma; PMBCL: primary mediastinal large B-cell lymphoma; HCC: hepatocellular carcinoma; MCC: merkel cell carcinoma; RCC: renal cell carcinoma; ORR: overall response rate; OR: overall response; OS: overall survival; PFS: progression-free survival; vs: versus; EFGR: epidermal growth factor receptor; ALK: anaplastic lymphoma kinase; ES: extensive stage; CPS: combined positive score; DOR: duration of response; ITT: intention to treat; NMPA: national medical products administration; TKI: tyrosine kinase inhibitor; NPC: nasopharyngeal cancer; DLT: dose-limiting toxicity; MTD: maximum tolerated dose; TNBC: triple-negative breast cancer; GC: gastric cancer; GEJC: gastroesophageal junction carcinoma; DCR: disease control rate; BTC: biliary tract cancer; TTR: time to response; PR: partial response; SD: stable disease; PD: progressive disease; IC₅₀: half maximal inhibitory concentration; IFN: interferon; HLA: human leukocyte antigen; NK: natural killer cell; M6PR: mannose-6-phosphate receptor; GrzB: granzyme B; TNF: tumor necrosis factor.

Targeting the immune milieu in gastrointestinal cancers

Gastrointestinal (GI) cancers are among the most common and lethal solid tumors worldwide. Unlike in malignancies such as lung, renal and skin cancers, the activity of immunotherapeutic agents in GI cancers has, on the whole, been much less remarkable and do not apply to the majority. Furthermore, while incremental progress has been made and approvals for use of immune checkpoint inhibitors (ICIs) in specific subsets of patients with GI cancers are coming through, in a population of 'all-comers', it is frequently unclear as to who may benefit most due to the relative lack of reliable predictive biomarkers. For most patients with newly diagnosed advanced or metastatic GI cancer, the mainstay of treatment still involves chemotherapy and/or a targeted agent however, beyond the second-line this paradigm confers minimal patient benefit. Thus, current research efforts are concentrating on broadening the applicability of ICIs in GI cancers by combining them with agents designed to beneficially remodel the tumor microenvironment (TME) for more effective anti-cancer immunity with intention of improving patient outcomes. This review will discuss the currently approved ICIs available for the treatment of GI cancers, the strategies underway focusing on combining ICIs with agents that target the TME and touch on recent progress toward identification of predictors of sensitivity to immune checkpoint blockade in GI cancers.

Interleukin-6-mediated resistance to immunotherapy is linked to impaired myeloid cell function

High serum levels of interleukin-6 (IL-6) correlate with poor prognosis and chemotherapy resistance in several cancers. The underlying mechanisms and its effects on immunotherapy are largely unknown. To address this, we developed a human papillomavirus type 16 (HPV16)-associated tumor model expressing IL-6 to investigate the impact of tumor-expressed IL-6 during cisplatin chemotherapy and HPV16 synthetic long peptide vaccination as immunotherapy. The effects of tumor-produced IL-6 on tumor growth, survival and the tumor microenvironment were analyzed. Our data demonstrated that tumor-produced IL-6 conferred resistance to cisplatin and therapeutic vaccination. This was not caused by a changed in vitro or in vivo growth rate of tumor cells, or a changed sensitivity of tumor cells to chemotherapy or T-cell-mediated killing. Furthermore, no overt differences in the frequencies of tumor-infiltrating subsets of T cells or CD11b⁺ myeloid cells were observed. IL-6, however, affected the systemic and local function of myeloid cells, reflected by a strong reduction of major histocompatibility complex (MHC) class II expression on all major myeloid cell subtypes. Resistance to both therapies was associated with a changed intratumoral influx of MHC class II⁺ myeloid cells toward myeloid cells with no or lower MHC class II expression. Importantly, while these IL-6-mediated effects provided resistance to the immunotherapy and chemotherapy as single therapies, their combination still successfully mediated tumor control. In conclusion, IL-6-mediated therapy resistance is caused by an extrinsic mechanism involving an impaired function of intratumoral myeloid cells. The fact that resistance can be overcome by combination therapies provides direction to more effective therapies for cancer.

Lack of myeloid cell infiltration as an acquired resistance strategy to immunotherapy

BACKGROUND

Immunotherapy of cancer is successful but tumor regression often is incomplete and followed by escape. Understanding the mechanisms underlying this acquired resistance will aid the development of more effective treatments.

METHODS

We exploited a mouse model where tumor-specific therapeutic vaccination results in tumor regression, followed by local recurrence and resistance. In depth studies on systemic, local and tumor intrinsic changes were performed with flow and mass cytometry, immunohistochemistry, transcriptomics and several perturbation studies with inhibitors or agonistic antibodies in mice. Main findings were recapitulated in vaccinated patients.

RESULTS

Full tumor regression and cure of tumor-bearing mice is dependent on the magnitude of the vaccine-induced T-cell response. Recurrence of tumors did not involve classical immune escape mechanisms, such as antigen-presentation alterations, immune checkpoint expression, resistance to killing or local immune suppression. However, the recurrent tumors displayed a changed transcriptome with alterations in p53, tumor necrosis factor-α and transforming growth factor-β signaling pathways and they became immunologically cold. Remarkably, ex vivo cell-sorted recurrent tumors, directly reinjected in naïve hosts retained their resistance to vaccination despite a strong infiltration with tumor-specific CD8⁺ T cells, similar to that of vaccine-responsive tumors. The influx of inflammatory mature myeloid effector cells in the resistant tumors, however, was impaired and this turned out to be the underlying mechanisms as restoration of inflammatory myeloid cell infiltration reinstated the sensitivity of these refractory tumors to vaccination. Notably, impaired myeloid cell infiltration after vaccination was also associated with vaccine resistance in patients.

CONCLUSION

An immunotherapy-induced disability of tumor cells to attract innate myeloid effector cells formed a major mechanism underlying immune escape and acquired resistance. These data not only stresses the importance of myeloid effector cells during immunotherapy but also demands for new studies to harness their tumoricidal activities.

Immunostimulation with chemotherapy in the era of immune checkpoint inhibitors

Conventional chemotherapeutics have been developed into clinically useful agents based on their ability to preferentially kill malignant cells, generally owing to their elevated proliferation rate. Nonetheless, the clinical activity of various chemotherapies is now known to involve the stimulation of anticancer immunity either by initiating the release of immunostimulatory molecules from dying cancer cells or by mediating off-target effects on immune cell populations. Understanding the precise immunological mechanisms that underlie the efficacy of chemotherapy has the potential not only to enable the identification of superior biomarkers of response but also to accelerate the development of synergistic combination regimens that enhance the clinical effectiveness of immune checkpoint inhibitors (ICIs) relative to their effectiveness as monotherapies. Indeed, accumulating evidence supports the clinical value of combining appropriately dosed chemotherapies with ICIs. In this Review, we discuss preclinical and clinical data on the immunostimulatory effects of conventional chemotherapeutics in the context of ICI-based immunotherapy.

Combination of Immune Checkpoint Inhibitors with Chemotherapy in Lung Cancer

Tremendous progress has been achieved in the field of immune checkpoint inhibitors (ICIs) therapy in lung cancer in recent years. To generate robust, long-lasting anti-tumor immune responses in lung cancer patients, combinational ICI therapies have been explored deeply. Conventionally, chemotherapy was considered as immunosuppressive. It is now recognized that chemotherapy could also reinstate cancer cell immune-surveillance and enable the perception of cancer cells as dangerous. That is to say that chemotherapeutic drugs are not only a source of direct cytotoxic effects but also an adjuvant for anti-tumor immunity. Recently, multiple clinical studies of ICIs combined with chemotherapeutic drugs have been explored and proved effective. However, there are still crucial questions that are not well addressed, such as the optimal dose and schedule for a given combination may differ across disease indications, and the appropriate strategy of selecting patient population that can benefit from ICIs remains unclear. To facilitate more rational lung cancer ICIs therapy development, this review summarizes the immune-regulatory effects and related mechanisms of chemotherapeutic drugs and the clinical progress of ICIs and their combination with chemotherapies in lung cancer treatment.

Activity and tolerability of maintenance avelumab immunotherapy after first line polychemotherapy including platinum in patients with locally advanced or metastatic squamous cell penile carcinoma: PULSE

Background Metastatic Squamous cell Penile Carcinoma (mSCPC) is an orphan disease with a virally induced oncogenesis. PD-L1 expression rate is around 60% with a strong correlation between PD-L1 in the primary tumour and metastases. The first line systemic treatment relies on platinum-based chemotherapies with a median progression free survival and overall survival around 7.5 and 16 months, respectively. Immunotherapies targeting PD-1/PD-L1 axis are effective in other squamous cell or HPV related cancers. Methods PULSE is a prospective multicenter open label single arm phase II study. Thirty-two patients will be enrolled after a radiological assessment showing a non-progressive disease after 3 to 6 cycles of a first line platinum-based polychemotherapy. Patients will receive Avelumab injections 10mg/ kg every two weeks until progression or unacceptable toxicity. The primary endpoint will be the progression free survival (PFS) according to RECIST v1.1 criteria. Secondary endpoints will include PFS according to iRECIST criteria, overall survival, quality of life, safety. Ancillary explorations will include assessing blood and tissue biomarkers for association with clinical benefit. Discussion After the first line, the prognosis remains poor with no consensus on a second line systemic treatment in locally advanced or mSCPC. PULSE trial is the first study that assess an anti PD-L1 immunotherapy in maintenance among patients with locally advanced or mSCPC. NCT NUMBER : NCT03774901.

Nanomicelle protects the immune activation effects of Paclitaxel and sensitizes tumors to anti-PD-1 Immunotherapy

Paclitaxel (PTX) has shown pleiotropic immunologic effects on the tumor microenvironment, and nanomicelle has emerged as a promising strategy for PTX delivery. However, the detailed mechanisms remain to be fully elucidated. Meanwhile, immunogenic cell death (ICD) is an effective approach to activate the immune system. This study investigated the ICD effect of PTX and how nanomicelle affected the immune-activation ability of PTX.

Methods: The ICD effects of PTX were identified via the expression of ICD markers and cell vaccine experiment. Tumor size and overall survival in multiple animal models with treatment were monitored to evaluate the antitumor effects. The mechanisms of PTX-induced ICD and antitumor immunity were determined by detecting gene expression related to ER stress and analyzing immune cell profile in tumor after treatment.

Results: We revealed the immune-regulation mechanism of PTX nanomicelle by inducing ICD, which can promote antigen presentation by dendritic cells (DCs) and activate antitumor immunity. Notably, nanomicelle encapsulation protected the ICD effects and immune activation, which were hampered by immune system impairment caused by chemotherapy. Compared with traditional formulations, a low dose of nanomicelle-encapsulated PTX (nano-PTX) treatment induced immune-dependent tumor control, which increased the infiltration and function of both T cells and DCs within tumors. However, this antitumor immunity was hampered by highly expressed PD-1 on tumor-infiltrating CD8⁺ T cells and upregulated PD-L1 on both immune cells and tumor cells after nano-PTX treatment. Combination therapy with a low dose of nano-PTX and PD-1 antibodies elicited CD8⁺ T cell-dependent antitumor immunity and remarkably improved the therapeutic efficacy.

Conclusions: Our results provide systemic insights into the immune-regulation ability of PTX to induce ICD, which acts as an inducer of endogenous vaccines through ICD effects, and also provides an experimental basis for clinical combination therapy with nano-PTX and PD-1 antibodies.

Old dogs, new trick: classic cancer therapies activate cGAS

The discovery of cancer immune surveillance and immunotherapy has opened up a new era of cancer treatment. Immunotherapies modulate a patient’s immune system to specifically eliminate cancer cells; thus, it is considered a very different approach from classic cancer therapies that usually induce DNA damage to cause cell death in a cell-intrinsic manner. However, recent studies have revealed that classic cancer therapies such as radiotherapy and chemotherapy also elicit antitumor immunity, which plays an essential role in their therapeutic efficacy. The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) and the downstream effector Stimulator of Interferon Genes (STING) have been determined to be critical for this interplay. Here, we review the antitumor roles of the cGAS-STING pathway during tumorigenesis, cancer immune surveillance, and cancer therapies. We also highlight classic cancer therapies that elicit antitumor immune responses through cGAS activation.

Chemotherapy but Not the Tumor Draining Lymph Nodes Determine the Immunotherapy Response in Secondary Tumors

Immunotherapies are used as adjuvant therapies for cancers. However, knowledge of how traditional cancer treatments affect immunotherapies is limited. Using mouse models, we demonstrate that tumor-draining lymph nodes (TdLNs) are critical for tumor antigen-specific T cell response. However, removing TdLNs concurrently with established primary tumors did not affect the immune checkpoint blockade (ICB) response on localized secondary tumor due to immunotolerance in TdLNs and distribution of antigen-specific T cells in peripheral lymphatic organs. Notably, treatment response improved with sequential administration of 5-fluorouracil (5-FU) and ICB compared with concurrent administration of ICB with 5-FU. Immune profiling revealed that using 5-FU as induction treatment increased tumor visibility to immune cells, decreased immunosuppressive cells in the tumor microenvironment, and limited chemotherapy-induced T cell depletion. We show that the effect of traditional cytotoxic treatment, not TdLNs, influences immunotherapy response in localized secondary tumors. We postulate essential considerations for successful immunotherapy strategies in clinical conditions.

Cisplatin educates CD8+ T cells to prevent and resolve chemotherapy-induced peripheral neuropathy in mice

The mechanisms responsible for the persistence of chemotherapy-induced peripheral neuropathy (CIPN) in a significant proportion of cancer survivors are still unknown. Our previous findings show that CD8 T cells are necessary for the resolution of paclitaxel-induced mechanical allodynia in male mice. In this study, we demonstrate that CD8 T cells are not only essential for resolving cisplatin-induced mechanical allodynia, but also to normalize spontaneous pain, numbness, and the reduction in intraepidermal nerve fiber density in male and female mice. Resolution of CIPN was not observed in Rag2 mice that lack T and B cells. Reconstitution of Rag2 mice with CD8 T cells before cisplatin treatment normalized the resolution of CIPN. In vivo education of CD8 T cells by cisplatin was necessary to induce resolution of CIPN in Rag2 mice because adoptive transfer of CD8 T cells from naive wild-type mice to Rag2 mice after completion of chemotherapy did not promote resolution of established CIPN. The CD8 T-cell-dependent resolution of CIPN does not require epitope recognition by the T-cell receptor. Moreover, adoptive transfer of cisplatin-educated CD8 T cells to Rag2 mice prevented CIPN development induced by either cisplatin or paclitaxel, indicating that the activity of the educated CD8 T is not cisplatin specific. In conclusion, resolution of CIPN requires in vivo education of CD8 T cells by exposure to cisplatin. Future studies should examine whether ex vivo CD8 T cell education could be applied as a therapeutic strategy for treating or preventing CIPN in patients.

Opportunities for Small Molecules in Cancer Immunotherapy

Cancer immunotherapy has proven remarkably successful through instigation of systemic antitumor T cell responses. Despite this achievement, further advancements are needed to expand the scope of susceptible cancer types and overcome variation in treatment outcomes between patients. Small-molecule drugs targeting defined pathways and/or cells capable of immune modulation are expected to substantially improve efficacy of cancer immunotherapy. Small-molecule drugs possess unique properties compatible with systemic administration and amenable to both extracellular and intracellular targets. These compounds can modify molecular pathways to overcome immune tolerance and suppression towards effective antitumor responses. Here, we provide an overview of how such effects might be achieved by combining immunotherapy with conventional and/or new small-molecule chemotherapeutics.

The interplay between innate and adaptive immunity in cancer shapes the productivity of cancer immunosurveillance

The immune system is a vital determinant of cancer and shapes its trajectory. Notably, the immune reaction to cancer harbors dual potential for suppressing or promoting cancer development and progression. This polarity of the immune response is determined, in part, by the character of the interplay between innate and adaptive immunity. On the one hand, the innate immune compartment is a necessary proponent of cancer immunity by supporting an immunostimulatory state that enables T cell immunosurveillance. However, in the setting of cancer, innate immune cells are commonly polarized with immune-suppressive properties and as a result, orchestrate a tolerogenic niche that interferes with the cytotoxic potential of tumor antigen-specific T cells. Here, we discuss the role of innate immunity as a positive and negative regulator of adaptive immunosurveillance; moreover, we highlight how tumor cells may skew leukocytes toward an immunosuppressive state and, as such, subvert the phenotypic plasticity of the immune compartment to advance disease progression. These observations establish the precedent for novel therapeutic strategies that aim to restore the tumor microenvironment to an immunoreactive state and, in doing so, condition and maintain the immunogenicity of tumors to yield deep and durable responses to immunotherapy.

Preparation and evaluation of the adjuvant effect of curdlan sulfate in improving the efficacy of dendritic cell-based vaccine for antitumor immunotherapy

Dendritic cell (DC) vaccine immunotherapy applies tumor antigens or tumor cell lysate (TCL)-pulsed DCs to induce an antigen-specific immune response to attack cancer cells. However, tumor antigen alone has limited immunostimulatory effects, and so immunostimulants are needed to prepare mature DCs. In our previous study, curdlan sulfate (CS) showed potent adjuvant properties with the HBV vaccine; therefore, we attempted to use CS to mature TCL-pulsed DCs. We first prepared four CSs (CS1-CS4) with different sulfation (S) degrees and molecular weights (MWs), then studied the structure-activity relationship of CS in vitro and finally screened CS3 (14.316% S content and 30.66 kDa MW) as the DC vaccine adjuvant. An in vivo study showed that a DC vaccine adjuvanted with CS3 significantly prolonged the survival of tumor-bearing mice, reduced tumor burden and inhibited tumor growth. The CS3-adjuvanted DC vaccine increased CD80, MHC-I and MHC-II expression, promoted CD8⁺ T cell infiltration, upregulated TNF-α and IFN-γ transcription, and downregulated TGF-β transcription in tumor tissues. A preliminary mechanism study showed that CS activated DCs mainly via the TLR4 and TLR2 signalling pathways. Based on these results, we concluded that CS3 is a potential adjuvant for DC vaccines and is worth studying for tumor immunotherapy.

Immune Checkpoint Inhibitors for the Treatment of Unresectable Stage III Non-Small Cell Lung Cancer: Emerging Mechanisms and Perspectives

There has been no improvement in outcome for patients with unresectable locally advanced (stage III) non-small cell lung cancer (NSCLC) for more than 10 years. The standard treatment for these patients is definitive concurrent chemotherapy and radiation (CCRT). Although the goal of treatment in this setting is to achieve a cure, most patients progress and their prognosis is poor, with a 5-year survival rate of 15-30%. There is thus an urgent need for the development of novel anticancer treatments in this patient population. Recent advances in cancer immunotherapy have led to a marked improvement in clinical outcome for advanced NSCLC. Such immunotherapy mainly consists of the administration of immune checkpoint inhibitors (ICIs) such as antibodies to cytotoxic T lymphocyte-associated protein-4 (CTLA-4) or to either programmed cell death-1 (PD-1) or its ligand PD-L1. Durvalumab (MEDI4736) is a high-affinity human immunoglobulin G1 monoclonal antibody that blocks the binding of PD-L1 on tumor cells or antigen-presenting cells to PD-1 on T cells. The PACIFIC study recently evaluated consolidation immunotherapy with durvalumab versus placebo administered after concurrent chemoradiotherapy (CCRT) in patients with unresectable stage III NSCLC. It revealed a significant improvement in both progression-free and overall survival with durvalumab, and this improvement was associated with a favorable safety profile. This achievement has made durvalumab a standard of care for consolidation after CCRT in patients with unresectable stage III NSCLC, and it has now been approved in this setting by regulatory agencies in the United States, Canada, Japan, Australia, Switzerland, Malaysia, Singapore, India, and the United Arab Emirates. In this review, we briefly summarize the results of the PACIFIC trial, including those of post hoc analysis, and we address possible molecular mechanisms, perspectives, and remaining questions related to combined treatment with CCRT and ICIs in this patient population.

Platinum Derivatives Effects on Anticancer Immune Response

Along with surgery and radiotherapy, chemotherapeutic agents belong to the therapeutic arsenal in cancer treatment. In addition to their direct cytotoxic effects, these agents also impact the host immune system, which might enhance or counteract their antitumor activity. The platinum derivative compounds family, mainly composed of carboplatin, cisplatin and oxaliplatin, belongs to the chemotherapeutical arsenal used in numerous cancer types. Here, we will focus on the effects of these molecules on antitumor immune response. These compounds can induce or not immunogenic cell death (ICD), and some strategies have been found to induce or further enhance it. They also regulate immune cells' fate. Platinum derivatives can lead to their activation. Additionally, they can also dampen immune cells by selective killing or inhibiting their activity, particularly by modulating immune checkpoints' expression.

Therapeutic Vaccines Against Human Papilloma Viruses: Achievements and Prospects

Human papillomaviruses of high carcinogenic risk (HR HPVs) are major etiological agents of malignant diseases of the cervix, vulva, penis, anal canal, larynx, head, and neck. Prophylactic vaccination against HPV, which mainly covers girls and women under 25, does not prevent vertical and horizontal HPV transmission in infants and children and does not have a therapeutic effect. As a result, a significant proportion of the population is not protected from the HPV infection and development of HPV-associated neoplastic transformation and cancer, which indicates the need for development and introduction of therapeutic HPV vaccines. Unlike prophylactic vaccines aimed at the formation of virus-neutralizing antibodies, therapeutic vaccines elicit cellular immune response leading to the elimination of infected and malignant cells expressing viral proteins. The ideal targets for vaccine immunotherapy are highly conserved HR HPV oncoproteins E6 and E7 expressed in precancerous and tumor tissues. Here, we describe expression of these proteins during different stages of HPV infection, their antigenic and immunogenic properties, and T-cell epitopes, the response to which correlates with natural regression of HPV-induced neoplastic changes. The review describes patterns of E6 and E7 oncoproteins presentation to the immune system as components of candidate vaccines along with the results of the most promising preclinical trials and animal models used in these trials. Special attention is paid to vaccine candidates which have shown efficacy in clinical trials in patients with HPV-associated neoplastic changes.

Cisplatin Facilitates Radiation-Induced Abscopal Effects in Conjunction with PD-1 Checkpoint Blockade Through CXCR3/CXCL10-Mediated T-cell Recruitment

PURPOSE

Localized radiotherapy can cause T-cell-mediated abscopal effects on nonirradiated metastases, particularly in combination with immune checkpoint blockade (ICB). However, results of prospective clinical trials have not met the expectations. We therefore investigated whether additional chemotherapy can enhance radiotherapy-induced abscopal effects in conjunction with ICB.

EXPERIMENTAL DESIGN

In three different two-tumor mouse models, triple therapy with radiotherapy, anti-PD-1, and cisplatin (one of the most widely used antineoplastic agents) was compared with double or single therapies.

RESULTS

In these mouse models, the response of the nonirradiated tumor and the survival of the mice were much better upon triple therapy than upon radiotherapy + anti-PD-1 or cisplatin + anti-PD-1 or the monotherapies; complete regression of the nonirradiated tumor was usually only observed in triple-treated mice. Mechanistically, the enhanced abscopal effect required CD8⁺T cells and relied on the CXCR3/CXCL10 axis. Moreover, CXCL10 was found to be directly induced by cisplatin in the tumor cells. Furthermore, cisplatin-induced CD8⁺T cells and direct cytoreductive effects of cisplatin also seem to contribute to the enhanced systemic effect. Finally, the results show that the abscopal effect is not precluded by the observed transient radiotherapy-induced lymphopenia.

CONCLUSIONS

This is the first report showing that chemotherapy can enhance radiotherapy-induced abscopal effects in conjunction with ICB. This even applies to cisplatin, which is not classically immunogenic. Whereas previous studies have focused on how to effectively induce tumor-specific T cells, this study highlights that successful attraction of the induced T cells to nonirradiated tumors is also crucial for potent abscopal effects.

New Insights into Mechanisms of Cisplatin Resistance: From Tumor Cell to Microenvironment

Although cisplatin has been a pivotal chemotherapy drug in treating patients with various types of cancer for decades, drug resistance has been a major clinical impediment. In general, cisplatin exerts cytotoxic effects in tumor cells mainly through the generation of DNA-platinum adducts and subsequent DNA damage response. Accordingly, considerable effort has been devoted to clarify the resistance mechanisms inside tumor cells, such as decreased drug accumulation, enhanced detoxification activity, promotion of DNA repair capacity, and inactivated cell death signaling. However, recent advances in high-throughput techniques, cell culture platforms, animal models, and analytic methods have also demonstrated that the tumor microenvironment plays a key role in the development of cisplatin resistance. Recent clinical successes in combination treatments with cisplatin and novel agents targeting components in the tumor microenvironment, such as angiogenesis and immune cells, have also supported the therapeutic value of these components in cisplatin resistance. In this review, we summarize resistance mechanisms with respect to a single tumor cell and crucial components in the tumor microenvironment, particularly focusing on favorable results from clinical studies. By compiling emerging evidence from preclinical and clinical studies, this review may provide insights into the development of a novel approach to overcome cisplatin resistance.

PD-L1 blockade engages tumor-infiltrating lymphocytes to co-express targetable activating and inhibitory receptors

BACKGROUND

The clinical benefit of immunotherapeutic approaches against cancer has been well established although complete responses are only observed in a minority of patients. Combination immunotherapy offers an attractive avenue to develop more effective cancer therapies by improving the efficacy and duration of the tumor-specific T-cell response. Here, we aimed at deciphering the mechanisms governing the response to PD-1/PD-L1 checkpoint blockade to support the rational design of combination immunotherapy.

METHODS

Mice bearing subcutaneous MC-38 tumors were treated with blocking PD-L1 antibodies. To establish high-dimensional immune signatures of immunotherapy-specific responses, the tumor microenvironment was analyzed by CyTOF mass cytometry using 38 cellular markers. Findings were further examined and validated by flow cytometry and by functional in vivo experiments. Immune profiling was extended to the tumor microenvironment of colorectal cancer patients.

RESULTS

PD-L1 blockade induced selectively the expansion of tumor-infiltrating CD4+ and CD8+ T-cell subsets, co-expressing both activating (ICOS) and inhibitory (LAG-3, PD-1) molecules. By therapeutically co-targeting these molecules on the TAI cell subsets in vivo by agonistic and antagonist antibodies, we were able to enhance PD-L1 blockade therapy as evidenced by an increased number of TAI cells within the tumor micro-environment and improved tumor protection. Moreover, TAI cells were also found in the tumor-microenvironment of colorectal cancer patients.

CONCLUSIONS

This study shows the presence of T cell subsets in the tumor micro-environment expressing both activating and inhibitory receptors. These TAI cells can be targeted by combined immunotherapy leading to improved survival.

Cisplatin and oxaliplatin induce similar immunogenic changes in preclinical models of head and neck cancer

OBJECTIVES

Prior studies suggest that oxaliplatin is unique among platinum chemotherapy drugs in its ability to enhance anti-tumor immunity, but the immune mechanisms of different platinum chemotherapy drugs have not been previously compared in preclinical models of head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Human HNSCC cell lines were treated with cisplatin or oxaliplatin, then assessed for markers associated with immunogenic cell death (ICD) and antigen processing. A syngeneic mouse model of oral cancer was then used to compare the effects of cisplatin vs. oxaliplatin, alone or in combination with anti-PD-1 immunotherapy, on tumor growth and survival. A subset of spleens and tumors were analyzed for ICD markers and immune cell infiltrates by flow cytometry.

RESULTS

Cisplatin and oxaliplatin both increased cell surface levels of calreticulin, HSP70, MHC class I and PD-L1 in multiple cell lines. Inoculation of immunocompetent mice with cells killed in vitro by either drug resulted in failure of subsequently-injected live tumor cells to establish and grow in a small proportion of animals. Systemic cisplatin and oxaliplatin induced similar tumor growth delay when combined with anti-PD-1 therapy.

CONCLUSIONS

Treatment of HNSCC cells with platinum chemotherapy appears to induce some features of anti-tumor immunity, which may be enhanced by anti-PD-1 therapy. Cisplatin, the standard drug for HNSCC, appears to affect anti-tumor immunity in a similar fashion to oxaliplatin in these preclinical models.

Characterization of the tumor immune micromilieu and its interference with outcome after concurrent chemoradiation in patients with oropharyngeal carcinomas

BACKGROUND

Intra-tumoral CD8 + T-cell infiltration in squamous cell carcinoma of the head and neck (HNSCC) has previously been linked to the efficacy of cisplatin-based chemoradiation (CDDP-CRTX) and immune checkpoint inhibitor (ICI) monotherapy. Further detailed characterization of the tumor immune-micromilieu and its influence on outcome may guide the development of CRTX-ICI combinations.

METHODS

Comprehensive immune transcriptome analysis was applied to a training set of tumor specimens from oropharyngeal squamous cell carcinoma (OPSCC) patients treated with CDDP-CRTX in the ARO-0401 phase III study (n = 33). A composite immune signature risk score (ISRS) for survival prediction was developed, and subsequently validated in two independent OPSCC cohorts treated with either CDDP-CRTX (n = 36) or mitomycin-based CRTX (MMC-CRTX, n = 31). Further validation of the ISRS was performed in the OPSCC subset (n = 79) of the TCGA HNSCC cohort. Potential interference between immune signatures and HPV status was evaluated in multivariate Cox regression models.

RESULTS

Significant differences according to the 3-y OS status in the abundance of tumor-infiltrating T- and B-cells, and the expression levels of 51 immune-related genes were observed. A risk score based on 13 differentially expressed genes involved in cytokine signaling, T-cell effector functions and the TNFR pathway was established as robust predictive factor of OS. Its predictive power was superior to the 6-gene interferon-gamma signature of ICI efficacy and independent of the HPV status.

CONCLUSIONS

This study further elucidates the complex interaction of the tumor immune microenvironment with the efficacy of CDDP-CRTX in OPSCC. The results suggest immune markers for selection of patients treated with CRTX-ICI combinations.

Dendritic Cells and Cancer: From Biology to Therapeutic Intervention

Inducing effective anti-tumor immunity has become a major therapeutic strategy against cancer. Dendritic cells (DC) are a heterogenous population of antigen presenting cells that infiltrate tumors. While DC play a critical role in the priming and maintenance of local immunity, their functions are often diminished, or suppressed, by factors encountered in the tumor microenvironment. Furthermore, DC populations with immunosuppressive activities are also recruited to tumors, limiting T cell infiltration and promoting tumor growth. Anti-cancer therapies can impact the function of tumor-associated DC and/or alter their phenotype. Therefore, the design of effective anti-cancer therapies for clinical translation should consider how best to boost tumor-associated DC function to drive anti-tumor immunity. In this review, we discuss the different subsets of tumor-infiltrating DC and their role in anti-tumor immunity. Moreover, we describe strategies to enhance DC function within tumors and harness these cells for effective tumor immunotherapy.

Chemotherapy-induced immunomodulation in non-small-cell lung cancer: a rationale for combination chemoimmunotherapy

Spurred by the survival benefits seen with the use of checkpoint blockade in non-small-cell lung cancer (NSCLC), there has been a growing interest in the potential applications of immunotherapy. Despite this, the objective response rate for single-agent immunotherapy remains ≤20% in patients with advanced NSCLC. A combinatorial approach that utilizes both chemotherapy and immunotherapy is a potential strategy to increase antitumor efficacy. Accumulating evidence has shown that the immunomodulatory effects of chemotherapeutic agents can be exploited in a combinational approach. Herein, we review the influence of specific chemotherapeutic agents on the tumor immune microenvironment in preclinical and clinical studies, and establish the rationale for combination chemoimmunotherapy for the treatment of NSCLC.

Cisplatin-induced immune modulation in ovarian cancer mouse models with distinct inflammation profiles

The backbone of ovarian cancer treatment is platinum-based chemotherapy and aggressive surgical debulking. New therapeutic approaches using immunotherapy via immune checkpoint blockade, which have demonstrated clinical efficacy in other tumor types, have been less promising in ovarian cancer. To increase their clinical efficacy, checkpoint inhibitors are now being tested in clinical trials in combination with chemotherapy. Here, we evaluated the impact of cisplatin on tumor immunogenicity and its in vivo roles when used alone or in combination with anti-PD-L1, in two novel murine ovarian cancer cell models. The 2F8 and its platinum-resistant derivative 2F8cis model, display distinct inflammatory profiles and chemotherapy sensitivities, and mirror the primary and recurrent human disease, respectively. Acute and chronic exposure to cisplatin enhances tumor immunogenicity by increasing calreticulin, MHC class I, antigen presentation and T-cell infiltration. Cisplatin also upregulates PD-L1 expression in vitro and in vivo, demonstrating a dual, paradoxical immune modulatory effect and supporting the rationale for combination with immune checkpoint blockade. One of the pathways activated by cisplatin treatment is the cGAS/STING pathway. Chronic cisplatin treatment led to upregulation of cGAS and STING proteins in 2F8cis compared to parental 2F8 cells, while acute exposure to cisplatin further increases cGAS and STING levels in both 2F8 and 2F8cis cells. Overexpression of cGAS/STING modifies tumor immunogenicity by upregulating PD-L1, MHC I and calreticulin in tumor cells. Anti-PD-L1 alone in a platinum-sensitive model or with cisplatin in a platinum-resistant model increases survival. These studies have high translational potential in ovarian cancer.

CD8+ cytotoxic T lymphocytes in cancer immunotherapy: A review

CD8⁺ cytotoxic T lymphocytes (CTLs) are preferred immune cells for targeting cancer. During cancer progression, CTLs encounter dysfunction and exhaustion due to immunerelated tolerance and immunosuppression within the tumor microenvironment (TME), with all favor adaptive immune-resistance. Cancer-associated fibroblasts (CAFs), macrophage type 2 (M2) cells, and regulatory T cells (Tregs) could make immunologic barriers against CD8 ⁺ T cell-mediated antitumor immune responses. Thus, CD8 ⁺ T cells are needed to be primed and activated toward effector CTLs in a process called tumor immunity cycle for making durable and efficient antitumor immune responses. The CD8 ⁺ T cell priming is directed essentially as a corroboration work between cells of innate immunity including dendritic cells (DCs) and natural killer (NK) cells with CD4 ⁺ T cells in adoptive immunity. Upon activation, effector CTLs infiltrate to the core or invading site of the tumor (so-called infiltrated-inflamed [I-I] TME) and take essential roles for killing cancer cells. Exogenous reactivation and/or priming of CD8 ⁺ T cells can be possible using rational immunotherapy strategies. The increase of the ratio for costimulatory to coinhibitory mediators using immune checkpoint blockade (ICB) approach. Programmed death-1 receptor (PD-1)-ligand (PD-L1) and CTL-associated antigen 4 (CTLA-4) are checkpoint receptors that can be targeted for relieving exhaustion of CD8 ⁺ T cells and renewing their priming, respectively, and thereby eliminating antigen-expressing cancer cells. Due to a diverse relation between CTLs with Tregs, the Treg activity could be dampened for increasing the number and rescuing the functional potential of CTLs to induce immunosensitivity of cancer cells.

Immunotherapy for non-small cell lung cancers: biomarkers for predicting responses and strategies to overcome resistance

Recent breakthroughs in targeted therapy and immunotherapy have revolutionized the treatment of lung cancer, the leading cause of cancer-related deaths in the United States and worldwide. Here we provide an overview of recent progress in immune checkpoint blockade therapy for treatment of non-small cell lung cancer (NSCLC), and discuss biomarkers associated with the treatment responses, mechanisms underlying resistance and strategies to overcome resistance. The success of immune checkpoint blockade therapies is driven by immunogenicity of tumor cells, which is associated with mutation burden and neoantigen burden in cancers. Lymphocyte infiltration in cancer tissues and interferon-γ-induced PD-L1 expression in tumor microenvironments may serve as surrogate biomarkers for adaptive immune resistance and likelihood of responses to immune checkpoint blockade therapy. In contrast, weak immunogenicity of, and/or impaired antigen presentation in, tumor cells are primary causes of resistance to these therapies. Thus, approaches that increase immunogenicity of cancer cells and/or enhance immune cell recruitment to cancer sites will likely overcome resistance to immunotherapy.

PD-1 Inhibition Minimally Affects Cisplatin-Induced Toxicities in a Murine Model

Immune checkpoint inhibition used in combination with standard cisplatin-based chemotherapy regimens is currently under evaluation in clinical trials for head and neck squamous cell carcinoma (HNSCC). The impact of anti-PD-1 therapy on cisplatin-induced ototoxicity and nephrotoxicity has not been established. Here we use a murine model of cisplatin-induced hearing loss to investigate the impact of anti-PD-1 immunotherapy on auditory brainstem responses (ABRs), distortion product otoacoustic emissions (DPOAEs), serum creatinine, and hair cell and renal histology. We demonstrate only mild worsening of DPOAEs at 14.4 and 16 kHz as well as a mild increase in serum creatinine. Renal and hair cell histology as well as ABR measures were unchanged by PD-1 inhibition. Thus, our data suggest that the use of PD-1 inhibition in conjunction with cisplatin results in toxicities that are similar to those of cisplatin alone.

Antagonist of cIAP1/2 and XIAP enhances anti-tumor immunity when combined with radiation and PD-1 blockade in a syngeneic model of head and neck cancer

Head and neck squamous cell carcinomas (HNSCCs) frequently harbor genomic mutations in cell death pathways. Nearly 30% of HNSCCs overexpress Fas-Associated Death Domain (FADD), with or without BIRC2/3 genes encoding cellular Inhibitor of Apoptosis Proteins 1/2 (cIAP1/2), critical components of the Tumor Necrosis Factor (TNF) Receptor signaling pathways. ASTX660 is a novel non-peptidomimetic antagonist of cIAP1/2 and XIAP under evaluation in a clinical trial for advanced solid tumors and lymphomas. Herein, we show that ASTX660, at nanomolar concentrations, sensitized Murine Oral Cancer (MOC1) cells to TNFα. Using syngeneic mouse models, ASTX660 showed additive anti-tumor activity with radiation therapy (XRT), cisplatin chemotherapy, and PD-1 blockade to significantly delay or eradicate MOC1 tumors. These combinations significantly increased CD8 + T cells and dendritic cells, as well as T cell activity. ASTX660 stimulated cytotoxic T lymphocyte (CTL) killing of MOC1 cells expressing ovalbumin. Early stages of CTL killing were predominantly mediated by perforin/granzyme B, whereas later stages were mediated by death ligands TNFα, TRAIL, and FasL. Correspondingly, depletion of CD8 + T cells and NK cells in vivo revealed both types of immune cells to be important components of the complete anti-tumor response enhanced by ASTX660+XRT. These findings serve to inform future studies of IAP inhibitors and support the potential for future clinical trials investigating ASTX660 with XRT and immunotherapies like PD-1/PD-L1 blockade in HNSCC.

Targeting phosphorylated p53 to elicit tumor-reactive T helper responses against head and neck squamous cell carcinoma

The human T cell receptor is capable of distinguishing between normal and post-translationally modified peptides. Because aberrant phosphorylation of cellular proteins is a hallmark of malignant transformation, the expression of the phosphorylated epitope could be an ideal antigen to combat cancer without damaging normal tissues. p53 activates transcription factors to suppress tumors by upregulating growth arrest and apoptosis-related genes. In response to DNA damage, p53 is phosphorylated at multiple sites including Ser33 and Ser37. Here, we identified phosphorylated peptide epitopes from p53 that could elicit effective T helper responses. These epitope peptides, p53_{22-41/Phospho-S33} and p53_{22-41/Phospho-S37}, induced T helper responses against tumor cells expressing the phosphorylated p53 protein. Moreover, chemotherapeutic agents augmented the responses of such CD4 T cells via upregulation of phosphorylated p53. The upregulation of phosphorylated p53 expression by chemotherapy was confirmed in in vitro and xenograft models. We evaluated phosphorylated p53 expression in the clinical samples of oropharyngeal squamous cell carcinoma and revealed that 13/24 cases (54%) were positive for phosphorylated p53. Importantly, the lymphocytes specific for the phosphorylated p53 peptide epitopes were observed in the head and neck squamous cell cancer (HNSCC) patients. These results reveal that a combination of phosphorylated p53 peptides and chemotherapy could be a novel immunologic approach to treat HNSCC patients.

Correlates of immune and clinical activity of novel cancer vaccines

Cancer vaccines are solely meant to amplify the pool of type 1 cytokine oriented CD4+ and CD8+ T cells that recognize tumor antigen and ultimately foster control and destruction of a growing tumor. They are not designed to deal with all aspects of immune ignorance, exclusion, suppression and escape that are generally in place in patients with cancer and may prevent the T cells to enter the tumor or to exert their effector function. This simple fact prompted for a reappraisal of the many recent trials in which therapeutic cancer vaccines have been examined as monotherapy. In this review, I focus on trials examining therapeutic cancer vaccines at different stages of existing disease. The analysis of vaccine-induced immune responses and clinical activity of therapeutic cancer vaccines revealed four levels of evidence for vaccine efficacy. The lowest levels, reflect the many trials in which the strength of the tumor-reactive T cell response of vaccinated patients is associated with better clinical outcome or change in tumor marker. The highest levels indicate occasional regressions of tumors and metastases after vaccination or reflect a stronger clinical impact of vaccine in a randomized trial. A whole series of trials in which vaccine-induced tumor immunity correlates with the clinical impact of cancer vaccines in premalignant diseases, settings of low tumor burden or tumor regressions in patients with cancer, form an attest to the fact that cancer vaccines work. While the current number of true clinical responders in each cancer trial is too low for firm conclusions on immune correlates of clinical reactivity in cancer, extrapolation of the results from vaccinated patients with pre-cancers suggest a requirement of broad type 1 T cell reactivity.

Recent advances in CD8+ regulatory T cell research

Various subgroups of CD8⁺ T lymphocytes do not only demonstrate cytotoxic effects, but also serve important regulatory roles in the body's immune response. In particular, CD8⁺ regulatory T cells (CD8⁺ Tregs), which possess important immunosuppressive functions, are able to effectively block the overreacting immune response and maintain the body's immune homeostasis. In recent years, studies have identified a small set of special CD8⁺ Tregs that can recognize major histocompatibility complex class Ib molecules, more specifically Qa-1 in mice and HLA-E in humans, and target the self-reactive CD4⁺ T ce lls. These findings have generated broad implications in the scientific community and attracted general interest to CD8⁺ Tregs. The present study reviews the recent research progress on CD8⁺ Tregs, including their origin, functional classification, molecular markers and underlying mechanisms of action.

Loss of C/EBP-β LIP drives cisplatin resistance in malignant pleural mesothelioma

OBJECTIVES

Cisplatin-based chemotherapy is moderately active in malignant pleural mesothelioma (MPM) due to intrinsic drug resistance and to low immunogenicity of MPM cells. CAAT/enhancer binding protein (C/EBP)-β LIP is a pro-apoptotic and chemosensitizing transcription factor activated in response to endoplasmic reticulum (ER) stress.

MATERIALS AND METHODS

We investigated if LIP levels can predict the clinical response to cisplatin and survival of MPM patients receiving cisplatin-based chemotherapy. We studied the LIP-dependent mechanisms determining cisplatin-resistance and we identified pharmacological approaches targeting LIP, able to restore cisplatin sensitiveness, in patient-derived MPM cells and animal models. Results were analyzed by a one-way analysis of variance test.

RESULTS

We found that LIP was degraded by constitutive ubiquitination in primary MPM cells derived from patients poorly responsive to cisplatin. LIP ubiquitination was directly correlated with cisplatin chemosensitivity and was associated with patients' survival after chemotherapy. Overexpression of LIP restored cisplatin's pro-apoptotic effect by activating CHOP/TRB3/caspase 3 axis and up-regulating calreticulin, that triggered MPM cell phagocytosis by dendritic cells and expanded autologous anti-tumor CD8⁺CD107⁺T-cytotoxic lymphocytes. Proteasome inhibitor carfilzomib and lysosome inhibitor chloroquine prevented LIP degradation. The triple combination of carfilzomib, chloroquine and cisplatin increased ER stress-triggered apoptosis and immunogenic cell death in patients' samples, and reduced tumor growth in cisplatin-resistant MPM preclinical models.

CONCLUSION

The loss of LIP mediates cisplatin resistance, rendering LIP a possible predictor of cisplatin response in MPM patients. The association of proteasome and lysosome inhibitors reverses cisplatin resistance by restoring LIP levels and may represent a new adjuvant strategy in MPM treatment.

Human papillomavirus E7 oncoprotein expression by keratinocytes alters the cytotoxic mechanisms used by CD8 T cells

Cervical cancer is a malignant transformation of keratinocytes initiated by the E7 oncoprotein of human papillomavirus (HPV). These tumors are characterized by keratinocyte hyperproliferation and are often infiltrated with activated CD8 T cells. HPV infection confers changes to gain immunological advantage to promote chronic infection, and these persist with malignant transformation. We investigated the relative importance of the many redundant mechanisms of cytotoxicity used by CD8 T cells to kill keratinocytes expressing HPV E7 oncoprotein using extended-duration time-lapse microscopy that allows examination of cell-to-cell interactions during killing. E7 expression by keratinocytes increased susceptibility to cell-mediated killing. However, while killing of non-transgenic keratinocytes was traditional, perforin-mediated, and caspase-dependent, E7-expression favored killing by perforin-independent, caspase-independent mechanisms. The roles of perforin, TNFα, IFNγ, Fas/FasL and PD1/PD-L1 were graded according to target cell survival to produce a hierarchy of killing mechanisms utilized in killing E7-expressing cells. TNFα was essential for perforin-mediated killing of E7-expressing cells, but not perforin-independent killing. IFNγ facilitated killing by Fas/FasL interaction, especially in the absence of perforin. Additionally, expression of E7 offered protection from killing by up regulation of PD-L1, Fas and FasL expression on keratinocytes promoting fight-back by target cells, resulting in effector cell death. This study shows that keratinocytes expressing E7 are highly susceptible to killing by CD8 T cells, but utilizing different armamentarium. Down-regulation of CD8 T cell cytotoxicity in HPV-related tumors may be due to suppression by E7-expressing keratinocytes. Immunotherapy for HPV-related cancers may be improved by suppression of PD-L1, or by suppression of FasL.

Unfavorable clinical implications of peripheral blood CD44+ and CD54+ lymphocytes in patients with lung cancer undergoing chemotherapy

BACKGROUND

There is an unmet need for identification of additional prognostic markers for lung cancer. The aim of this study was to identify novel clinical and immunological predictors of prognosis in lung cancer patients.

METHODS

Lymphocyte subsets CD3+, CD4+, CD8+, CD4+/8+, CD25+, CD69+, CD44+ and CD54+ were quantified in peripheral blood using flow cytometry, for 203 newly diagnosed lung cancer patients and 120 healthy controls.

RESULTS

The levels of CD3+, CD4+, CD8+, CD4+/CD8+ and CD69+ lymphocytes were significantly lower in patients with lung cancer compared with the healthy control group, while CD54+ and CD44+ lymphocytes were significantly higher. In stage III/IV patients with lymph node metastasis or distant metastasis, the levels of CD44+ and CD54+ lymphocytes were significantly increased compared with patients with stage I/II disease (p<0.05). The levels of CD44+ and CD54+ lymphocytes markedly reduced after chemotherapy, and follow-up analysis indicated that patients found without increase of CD44+ and CD54+ lymphocytes after chemotherapy had survival advantages. Independent predictors of survival in lung cancer patients included clinical stage (hazard ratio [HR] = 2.791; 95% confidence interval [95% CI], 1.42-3.54, p<0.001), CD44+ lymphocytes (HR = 1.282; 95% CI, 1.02-1.49, p = 0.002) and CD54+ lymphocytes (HR = 1.475; 95% CI, 1.22-1.73, p = 0.003). Elevated levels of CD44+ and CD54+ lymphocytes correlated with poor prognosis in lung cancer patients.

CONCLUSIONS

Peripheral blood lymphocyte subsets in patients with lung cancer are different from those in healthy people, and circulating CD44+ and CD54+ lymphocytes seem to be a promising criterion to predict survival in lung cancer patients undergoing chemotherapy.

Two immune-enhanced molecular subtypes differ in inflammation, checkpoint signaling and outcome of advanced head and neck squamous cell carcinoma

The immune environment of primary tumor is associated with the clinical response and benefit of immunotherapy. This study aims to investigate the intratumoral immune profile and its clinical relevance in advanced head and neck squamous cell carcinoma (HNSCC). Gene expression profiles of 401 HNSCCs at stage III-IVB from two cohorts (The Cancer Genome Atlas, TCGA, n = 203; the Leipzig Head and Neck Group, LHNG, n = 198) were involved in this analysis. Based on the global immune-related genes, four gene expression subtypes (C1-4) were identified in HNSCCs. Overall, subtypes C2 and C3 showed upregulation of immune profiles and increased tumor lymphocyte infiltration, exhibiting an enhanced immune microenvironment (EIME). However, the two EIME subtypes revealed differences in immune markers and clinical features. Subtype C2 showed higher expression of macrophage signature, whereas subtype C3 was more associated with B cell infiltration. T cell and NK cell infiltration was not different between C2 and C3 subtypes. The subtype C2 tumors were characterized by inflammation compared with subtype C3. Although the checkpoint receptors PD1 and CTLA4 expressed equally between the EIME subtypes, their ligands (PD-L1/PD-L2, CD86/CD80) were significantly upregulated in subtype C2 compared with C3. HPV-positive tumors were predominantly enriched in subtype C3 but not in C2. Furthermore, patients in subtype C2 had a worse outcome than those in C3. In summary, two immune-enhanced subtypes with different immune characteristics and clinical features were identified in advanced HNSCC. The different immune microenvironments among HNSCC subgroups may provide new insights into the strategy of immunotherapy.

Cisplatin Alters Antitumor Immunity and Synergizes with PD-1/PD-L1 Inhibition in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) has been treated for decades with cisplatin chemotherapy, and anti-PD-1 immunotherapy has recently been approved for the treatment of this disease. However, preclinical studies of how antitumor immunity in HNSCC is affected by cisplatin alone or in combination with immunotherapies are lacking. Here, we show that sublethal doses of cisplatin may enhance antigen presentation and T-cell killing in vitro, though cisplatin also upregulates tumor cell expression of PD-L1 and may impair T-cell function at higher doses. In a syngeneic mouse model of HNSCC, concurrent use of cisplatin and anti-PD-L1/PD-1 delayed tumor growth and enhanced survival without significantly reducing the number or function of tumor-infiltrating immune cells or increasing cisplatin-induced toxicities. These results suggest that moderate doses of cisplatin may enhance antitumor immunity by mechanisms other than direct tumor cell killing, which may be further enhanced by anti-PD-L1/PD-1 therapy. Cancer Immunol Res; 5(12); 1141-51. ©2017 AACR.