Regression of melanoma metastases following treatment with the n-bisphosphonate zoledronate and localised radiotherapy

Long noncoding RNA Malat1 protects against osteoporosis and bone metastasis

MALAT1, one of the few highly conserved nuclear long noncoding RNAs (lncRNAs), is abundantly expressed in normal tissues. Previously, targeted inactivation and genetic rescue experiments identified MALAT1 as a suppressor of breast cancer lung metastasis. On the other hand, Malat1-knockout mice are viable and develop normally. On a quest to discover the fundamental roles of MALAT1 in physiological and pathological processes, we find that this lncRNA is downregulated during osteoclastogenesis in humans and mice. Remarkably, Malat1 deficiency in mice promotes osteoporosis and bone metastasis of melanoma and mammary tumor cells, which can be rescued by genetic add-back of Malat1. Mechanistically, Malat1 binds to Tead3 protein, a macrophage-osteoclast-specific Tead family member, blocking Tead3 from binding and activating Nfatc1, a master regulator of osteoclastogenesis, which results in the inhibition of Nfatc1-mediated gene transcription and osteoclast differentiation. Notably, single-cell transcriptome analysis of clinical bone samples reveals that reduced MALAT1 expression in pre-osteoclasts and osteoclasts is associated with osteoporosis and metastatic bone lesions. Altogether, these findings identify Malat1 as a lncRNA that protects against osteoporosis and bone metastasis.

Discovery and Evaluation of C6-Substituted Pyrazolopyrimidine-Based Bisphosphonate Inhibitors of the Human Geranylgeranyl Pyrophosphate Synthase and Evaluation of Their Antitumor Efficacy in Multiple Myeloma, Pancreatic Ductal Adenocarcinoma, and Colorectal Cancer

Novel C6-substituted pyrazolo[3,4-d]pyrimidine- and C2-substituted purine-based bisphosphonate (C6-PyraP-BP and C2-Pur-BP, respectively) inhibitors of the human geranylgeranyl pyrophosphate synthase (hGGPPS) were designed and evaluated for their ability to block the proliferation of multiple myeloma (MM), pancreatic ductal adenocarcinoma (PDAC), and colorectal cancer (CRC) cells. Pyrazolo[3,4-d]pyrimidine analogs were identified that induce selective intracellular target engagement leading to apoptosis and downregulate the prenylation of Rap-1A in MM, PDAC, and CRC cells. The C6-PyraP-BP inhibitor RB-07-16 was found to exhibit antitumor efficacy in xenograft mouse models of MM and PDAC, significantly reducing tumor growth without substantially increasing liver enzymes or causing significant histopathologic damage, usually associated with hepatotoxicity. RB-07-16 is a metabolically stable compound in cross-species liver microsomes, does not inhibit key CYP 450 enzymes, and exhibits good systemic circulation in rat. Collectively, the current studies provide encouraging support for further optimization of the pyrazolo[3,4-d]pyrimidine-based GGPPS inhibitors as potential human therapeutics for various cancers.

Targeting Melanoma-Associated Fibroblasts (MAFs) with Activated γδ (Vδ2) T Cells: An In Vitro Cytotoxicity Model

The tumor microenvironment (TME) has gained considerable scientific attention by playing a role in immunosuppression and tumorigenesis. Besides tumor cells, TME is composed of various other cell types, including cancer-associated fibroblasts (CAFs or MAFs when referring to melanoma-derived CAFs) and tumor-infiltrating lymphocytes (TILs), a subpopulation of which is labeled as γδ T cells. Since the current anti-cancer therapies using γδ T cells in various cancers have exhibited mixed treatment responses, to better understand the γδ T cell biology in melanoma, our research group aimed to investigate whether activated γδ T cells are capable of killing MAFs. To answer this question, we set up an in vitro platform using freshly isolated Vδ2-type γδ T cells and cultured MAFs that were biobanked from our melanoma patients. This study proved that the addition of zoledronic acid (1-2.5 µM) to the γδ T cells was necessary to drive MAFs into apoptosis. The MAF cytotoxicity of γδ T cells was further enhanced by using the stimulatory clone 20.1 of anti-BTN3A1 antibody but was reduced when anti-TCR γδ or anti-BTN2A1 antibodies were used. Since the administration of zoledronic acid is safe and tolerable in humans, our results provide further data for future clinical studies on the treatment of melanoma.

Extra-Axial Skeletal Metastasis of Malignant Melanoma: Case Report and Literature Review

The incidence of malignant melanoma is increasing worldwide and is one of the major causes of skin cancer deaths in the United States. Although melanoma has the potential to metastasize to any organ, the incidence of bone metastasis is low (~25%) compared to liver or lung metastasis. However, when a bone is involved, metastasis occurs to the axial skeleton in most cases (80%-90%), and involvement of the appendicular skeleton is relatively rare. We here describe the case of a patient who presented with a pathological fracture due to extra-axial skeletal metastasis of a widespread malignant melanoma. 

A 45-year-old female with an unremarkable past medical history presented to the ED with acute left hip pain. X-ray demonstrated left intertrochanteric femur fracture with an abnormal, suspicious lesion at the fracture site. Detailed physical examination revealed various skin nodules on the anterior chest wall, right upper back, and left cheek. CT of the chest/abdomen/pelvis (CT C/A/P) showed multiple lytic bone lesions and metastatic lesions in lungs, soft tissue, and mediastinal lymph nodes. She underwent surgical stabilization of the fracture, and a biopsy of the bone lesion revealed metastatic malignant melanoma with BRAF V600E mutation. She was started on localized radiotherapy followed by targeted therapy (dabrafenib and trametinib) and denosumab for her stage IV (cTX, cN2, cM1b(1)) (American Joint Committee on Cancer [AJCC] cancer staging 8th edition) disease. Despite treatment, her disease progressed as evidenced by the presence of new metastatic foci on a positron emission tomography-computed tomography (PET-CT) scan performed at a three-month follow-up. Her clinical course was complicated by hemoperitoneum due to bleeding from metastatic liver lesions and respiratory failure requiring a prolonged stay in the ICU before she was deceased.

In most cases, malignant melanoma presents with skin lesions at an early stage. Very few patients (4%) have metastatic disease at presentation. Although metastasis to bone is known to occur in advanced disease, involvement of the extra-axial skeleton is relatively rare. Malignant melanoma, initially presenting as pathological fracture of the appendicular skeleton, is not commonly encountered. Our case emphasizes the aggressive nature of malignant melanoma with an aim to raise physicians' awareness of this uncommon presentation. A brief review of the literature exploring prognosis and currently available treatment options is discussed.

Synthesis and Evaluation of Structurally Diverse C-2-Substituted Thienopyrimidine-Based Inhibitors of the Human Geranylgeranyl Pyrophosphate Synthase

Novel analogues of C-2-substituted thienopyrimidine-based bisphosphonates (C2-ThP-BPs) are described that are potent inhibitors of the human geranylgeranyl pyrophosphate synthase (hGGPPS). Members of this class of compounds induce target-selective apoptosis of multiple myeloma (MM) cells and exhibit antimyeloma activity in vivo. A key structural element of these inhibitors is a linker moiety that connects their (((2-phenylthieno[2,3-d]pyrimidin-4-yl)amino)methylene)bisphosphonic acid core to various side chains. The structural diversity of this linker moiety, as well as the side chains attached to it, was investigated and found to significantly impact the toxicity of these compounds in MM cells. The most potent inhibitor identified was evaluated in mouse and rat for liver toxicity and systemic exposure, respectively, providing further optimism for the potential value of such compounds as human therapeutics.

Dysfunctional BTN3A together with deregulated immune checkpoints and type I/II IFN dictate defective interplay between pDCs and γδ T cells in melanoma patients, which impacts clinical outcomes

Objectives

pDCs and γδ T cells emerge as potent immune players participating in the pathophysiology of cancers, yet still remaining enigmatic while harbouring a promising potential for clinical translations. Despite strategic and closed missions, crosstalk between pDCs and γδ T cells has not been deciphered yet in cancers, especially in melanoma where the long‐term control of the tumor still remains a challenge.

Methods

This prompted us to explore the interplay between pDCs and γδ T cells in the context of melanoma, investigating the reciprocal features of pDCs or γδ T cells, the underlying molecular mechanisms and its impact on clinical outcomes.

Results

TLRL‐activated pDCs from the blood and tumor infiltrate of melanoma patients displayed an impaired ability to activate, to modulate immune checkpoints and trigger the functionality of γδ T cells. Conversely, γδ T cells from the blood or tumor infiltrate of melanoma patients activated by PAg were defective in triggering pDCs’ activation and modulation of immune checkpoints, and failed to elicit the functionality of pDCs. Reversion of the dysfunctional cross‐talks could be achieved by specific cytokine administration and immune checkpoint targeting. Strikingly, we revealed an increased expression of BTN3A on circulating and tumor‐infiltrating pDCs and γδ T cells from melanoma patients, but stressed out the potential impairment of this molecule.

Conclusion

Our study uncovered that melanoma hijacked the bidirectional interplay between pDCs and γδ T cells to escape from immune control, and revealed BTN3A dysfunction. Such understanding will help harness and synergise the power of these potent immune cells to design new therapeutic approaches exploiting their antitumor potential while counteracting their skewing by tumors to improve patient outcomes.

Preliminary analysis of distinct clinical and biologic features of bone metastases in melanoma

Melanoma disseminates to the skeletal system where it is then difficult to treat. Yet, there remains limited research investigating metastatic bone disease (MBD) in melanoma. Here, we evaluate whether there are distinct clinicopathologic variables at the time of primary melanoma diagnosis that predispose metastases to engraft bone, and we test the hypothesis that patients with MBD have different responses to treatment. Cutaneous melanoma patients enrolled in a prospective database were studied. Individuals with metastatic melanoma and bone metastases (M-Bone) were compared to those with metastatic disease but no M-Bone. Of the 463 (42.7%) patients, 198 with unresectable metastatic melanoma had M-Bone and 98 developed bone metastasis (bone mets) as first site. Progression-free survival and overall survival were significantly worse in patients with M-Bone compared to those without M-Bone (P < 0.001) independent of treatment modalities, and in patients whose melanoma spread to bone first, compared to those who developed first mets elsewhere (P < 0.001). Interestingly, patients with bone mets presented with primary tumors that had more tumor infiltrating lymphocytes (P < 0.001) and less often a nodular histologic subtype compared to patients without M-Bone (P < 0.001). Our data suggest that melanoma bone metastasis is a distinct clinical and biological entity that cannot be explained by generalized metastatic phenotype in all patients. The observed dichotomy between more favorable primary histopathologic characteristics and a grave overall prognosis requires more studies to elucidate the molecular processes by which melanomas infiltrate bone and to build a mechanistic understanding of how melanoma bone metastases yield such detrimental outcomes.

Zoledronic Acid Inhibits the RhoA-mediated Amoeboid Motility of Prostate Cancer Cells

BACKGROUND

The bisphosphonate Zoledronic acid (ZA) is a potent osteoclast inhibitor currently used in the clinic to reduce osteoporosis and cancer-induced osteolysis. Moreover, ZA exerts an anti-tumor effect in several tumors. Despite this evidence, the relevance of ZA in prostate cancer (PCa) is not completely understood.

OBJECTIVE

To investigate the effect of ZA administration on the invasive properties of PC3 cells, which are characterised by RhoA-dependent amoeboid motility.

METHODS

The effect of ZA administration on the in vitro invasive properties of PC3 cells was evaluated by cell migration in 3D collagen matrices, immunofluorescence and Boyden assays or transendothelial migration. Lung retention and colonization assays were performed to assess the efficacy of ZA administration in vivo.

RESULTS

PC3 cells are characterised by RhoA-dependent amoeboid motility. We now report a clear inhibition of in vitro PC3 cell invasion and RhoA activity upon ZA treatment. Moreover, to confirm a specific role of ZA in the inhibition of amoeboid motility of PC3 cells, we demonstrate that ZA interferes only partially with PC3 cells showing a mesenchymal phenotype due to both treatment with conditioned medium of cancer associated fibroblasts or to the acquisition of chemoresistance. Furthermore, we demonstrate that ZA impairs adhesion to endothelial cells and the trans-endothelial cell migration, two essential properties characterising amoeboid motility and PC3 metastatic dissemination. In vivo experiments prove the ability of ZA to inhibit the metastatic process of PC3 cells as shown by the decrease in lung colonization.

CONCLUSION

This study demonstrates that ZA inhibits Rho-dependent amoeboid motility of PC3 cells, thus suggesting ZA as a potential therapy to impede the metastatic dissemination of PC3 cells.

Synergistic induction of apoptosis in a cell model of human leukemia K562 by nitroglycerine and valproic acid

Nitroglycerin (NG), a nitric oxide donor, and valproic acid (VPA), an inhibitor of histone deacetylases, have impressive effects on numerous cancer cell lines. This study intended to evaluate synergistic effects of NG and VPA on cell viability and apoptosis in K562 cells. K562 cells were cultured in RPMI-1640 supplemented with 10 % heat-inactivated FBS. They were treated with different doses of NG, VPA and cisplatin for 24, 48, and 72 h, and MTT assay was performed to analyze cell viability. Also, Peripheral blood mononuclear cells (PBMC) were cultured in RPMI-1640 media and incubated with NG (200 μM), VAP (100 μM), NG+VPA (150 μM) and cisplatin (8 μM) to evaluate cytotoxicity. IC₅₀ of the drugs, when they were applied separately and in combination, were calculated using the COMPUSYN software. DNA electrophoresis, TUNEL assay, and Hoechst staining were performed to investigate apoptosis induction. RT-PCR was used for the evaluation of apoptotic genes expression. The results of the MTT assay showed that cell viability decreased at all applied doses of NG and VPA. It was noticed that the cytotoxic effects of these drugs were dose- and time-dependent. Based on the COMPUSYN output, the combination of the drugs (VPA and NG) in a certain ratio concentration synergistically decreased cell viability. Cisplatin significantly decreased cell viability of PBMCs and K562 cells. Also, the combination drug had cytotoxic effect and significantly reduced viability of K562 cells compared with PBMCs and control cells. In the target cells treated with this combination, Bax and caspase-3 expression increased but Bcl-2 expression decreased. These results suggest that NG, VPA, and their combination decreased cell viability and induced apoptosis via the intrinsic apoptotic pathway. This study suggests that this combination therapy can be considered for further evaluation as an effective chemotherapeutic strategy for patients with chronic myeloid leukemia.

Γδ T Cell-Based Immunotherapy in Melanoma: State of the Art

Metastatic melanoma is still associated with a poor prognosis, and there is increasing interest in immunotherapy alone or in combination with other adjuvant therapies. Γδ T lymphocytes play a pivot role in the immune response against cancer, but while γδ-based immunotherapy is already a clinical reality for several solid tumors, data on melanoma are still limited and fragmented. This systematic review presents preclinical and clinical evidence for a role of γδ T lymphocytes in immunotherapeutic strategies for advanced melanoma and discusses research state of the art and future perspectives. Current strategies focus on in vivo stimulation, and ex vivo adoptive therapy and vaccination; results are promising, but further studies are needed to better investigate the interactions in tumoral microenvironment and to improve clinical efficacy of immunotherapeutic protocols.

The features of circulating and tumor-infiltrating γδ T cells in melanoma patients display critical perturbations with prognostic impact on clinical outcome

γδT cells hold a pivotal role in tumor immunosurveillance through their prompt activation and cytokine secretion, their ability to kill tumor cells in an Human Leukocyte Antigen (HLA)-unrestricted manner, and their combination of features of both innate and adaptive immunity. These unique properties and functional plasticity render them very attractive both as targets and vectors for cancer immunotherapy. Yet, these potent and fascinating antitumor effectors have not been extensively explored in melanoma. We provided here a detailed investigation of the phenotypic and functional properties of circulating and tumor-infiltrating γδT cells in melanoma patients, and their impact on clinical evolution. High proportions of circulating- and tumor-infiltrating γδT and δ2+ subset were associated with better clinical outcome. We reported however that circulating and tumor-infiltrating γδT cells from melanoma patients displayed an altered expression of NCR, KIR, and immune checkpoints, and identified NKp44, PD1, 41BB/41BBL, TIM3, and LAG3 as crucial checkpoints allowing immune escape and tumor progression. Notably, melanoma drastically impaired the ability of γδT cells to exhibit activation molecules, secrete cytokines, and display cytotoxicity toward melanoma in response to stimulation with phosphoantigens. It drove them toward regulatory and Th17 profiles associated with poor clinical outcomes. Our study highlights that melanoma hijacked γδT cells to escape from immune control, and revealed that circulating and tumor-infiltrating γδT cell features are promising potential biomarkers of clinical evolution. Such understanding of the physiopathology of γδT cells may help designing new therapeutic approaches exploiting the antitumor potential of γδT cells while counteracting their skewing by tumors to improve patient outcomes.

The role of lipid signaling in the progression of malignant melanoma

In the past decades, a vast amount of data accumulated on the role of lipid signaling pathways in the progression of malignant melanoma, the most metastatic/aggressive human cancer type. Genomic studies identified that PTEN loss is the leading factor behind the activation of the PI3K-signaling pathway in melanoma, mutations of which are one of the main resistance mechanisms behind target therapy failures. On the other hand, illegitimate expressions of megakaryocytic genes p12-lipoxyganse, cyclooxygenase-2, and phosphodiestherase-2/autotaxin (ATX) are mostly involved in the regulation of motility signaling in melanoma through various G-protein-coupled bioactive lipid receptors. Furthermore, endocannabinoid signaling can also be a novel paracrine survival factor in melanoma. Last but not least, prenylation inhibitors acting even on mutated small GTP-ases, such as NRAS of melanoma may offer novel therapeutic opportunities. As regards melanoma, the most effective therapy nowadays is immunotherapy, with the resistance mechanisms also possibly involving the lipid signaling activities of melanoma cells, which further supports the idea of their being therapeutic targets.

Complications of bone metastases from malignant melanoma

INTRODUCTION

Metastatic bone disease (MBD) carries significant morbidity for patients with cancer. MBD from malignant melanoma (MM) is understudied. We examined the characteristics, morbidity, management and outcome of MBD in patients with MM.

METHODS

Patients with metastatic MM managed at two referral cancer centres in England were identified. Those with bone metastases (BMs) were selected. Patient and disease characteristics including skeletal related events (SREs) were extracted from medical records. The Kaplan Meier method was used to calculate median survival.

RESULTS

Five hundred and eighteen patients with metastatic MM were managed between years 2000 and 2008. Eighty nine (17.2%) patients had BMs and are the subject of this study. Median age at diagnosis was 53 years and 55% were males. BMs were identified at the time of diagnosis of metastatic disease in 68.5% patients. Sixty-six (74.2%) had multiple bone lesions and 80.9% had axial skeleton involvement. One hundred and twenty nine skeletal related events occurred in 59 (66.3%) patients (50 radiotherapy, 28 hypercalcaemia, 20 bone fractures, 18 spinal cord compression and 13 orthopaedic surgery). The annual skeletal morbidity rate was 2.5. Median survival from diagnosis of BMs was 17.3 weeks and was 5.6 weeks from the first episode of hypercalcaemia.

CONCLUSION

MBD affects a clinically important proportion (17.2%) of patients with metastatic MM. It carries a substantial morbidity and mortality exceeding that caused by BMs from breast and prostate cancer. These patients should receive the currently licensed bone modifying agents and should be included in clinical trials addressing MBD.

Repurposing Drugs in Oncology (ReDO)-nitroglycerin as an anti-cancer agent

Nitroglycerin (NTG), a drug that has been in clinical use for more than a century, has a range of actions which make it of particular interest in an oncological setting. It is generally accepted that the main mechanism of action of NTG is via the production of nitric oxide (NO), which improves cardiac oxygenation via multiple mechanisms including improved blood flow (vasodilation), decreased platelet aggregation, increased erythrocyte O2 release and decreased mitochondrial utilization of oxygen. Its vasoactive properties mean that it has the potential to exploit more fully the enhanced permeability and retention effect in delivering anti-cancer drugs to tumour tissues. Moreover NTG can reduce HIF-1α levels in hypoxic tumour tissues and this may have anti-angiogenic, pro-apoptotic and anti-efflux effects. Additionally NTG may enhance anti-tumour immunity. Pre-clinical and clinical data on these anti-cancer properties of NTG are summarised and discussed. While there is evidence of a positive action as a monotherapy in prostate cancer, there are mixed results in NSCLC where initially positive results have yet to be fully replicated. Based on the evidence presented, a case is made that further exploration of the clinical benefits that may accrue to cancer patients is warranted. Additionally, it is proposed that NTG may synergise with a number of other drugs, including other repurposed drugs, and these are discussed in the supplementary material appended to this paper.

Stability, prognostic factors and survival of spinal bone metastases in malignant melanoma patients after palliative radiotherapy

PURPOSE

This retrospective analysis aimed to evaluate the stability of spinal metastases in malignant melanoma patients following radiotherapy (RT), and to assess prognostic factors for survival.

METHODS

Forty-one patients with malignant melanoma and osteolytic spinal bone metastases were irradiated at the university clinics of Heidelberg and Mainz between July 2003 and October 2013. Three and six months after palliative RT, only 20 and 15 patients, respectively, were still alive and were therefore assessed for spinal stability using the Taneichi score based on CT imaging. Additionally, overall survival (OS) and bone survival (BS) rates as well as prognostic factors for BS were evaluated for all study patients.

RESULTS

Before RT, 19 patients (46.3%) were rated unstable. In the surviving patients, none of the unstable metastases were classified as stable 6 months after RT. Five-year OS was 23.3% and median BS was 4 months (range 0.5-29.8). Accordingly, only 36.6% of the patients were still alive 6 months after RT. Karnofsky performance score (KPS) &lt;70%, visceral metastases and more than one bone metastasis were significantly predictive of poor BS.

CONCLUSIONS

Our study population was characterized by poor BS and a lack of benefit with regard to stabilization of initially unstable spinal bone metastases 3 and 6 months after RT. This applies in particular to patients with a KPS &lt;70%, visceral metastases and multiple bone metastases. Given the limited life expectancy, short fractionated treatment schedules of RT may be preferred in this population.

Primary MHC-class II(+) cells are necessary to promote resting Vδ2 cell expansion in response to (E)-4-hydroxy-3-methyl-but-2-enyl-pyrophosphate and isopentenyl pyrophosphate

Human Vγ9δ2 (Vδ2) T cells represent a unique effector T cell population in humans and primates detecting nonpeptid phosphoantigens, playing an important role in antimicrobial and antitumor immunity. Currently, it is believed that various leukocyte subsets can promote phosphoantigen-driven Vδ2 cell expansion, but the essential cell type required remains elusive. We have used high purity cell sorting to analyze the cellular requirements for (E)-4-hydroxy-3-methyl-but-2-enyl-pyrophosphate (HMBPP)-driven Vδ2 cell expansion. To our knowledge, we show for the first time that primary human MHC-class II(+) cells are indispensable for HMBPP- and isopentenylpyrophosphate-driven Vδ2 cell expansion. In contrast, MHC-class II(-) cells are unable to promote Vδ2 cell expansion. Moreover, purified primary human TCRαβ(+) T cells, CD4(+), or CD8(+) T cells also failed to promote HMBPP-mediated Vδ2 expansion. Depletion of CD4(+)CD25(+) T cells demonstrated that inability of TCRαβ(+) cells to expand Vδ2 cells was not related to the presence of regulatory T cells. Separation of MHC-class II(+) cells into dendritic cells, monocytes, and B cells revealed that dendritic cells were the most potent Vδ2 expanders. Pulsing experiments demonstrated that HMBPP transforms MHC-class II(+) but not negative cells into Vδ2 expanders. MHC-class II-blocking experiments with mAbs and secondary MHC-class II induction on CD4(+) T cells after CD3/CD28 costimulation indicated that MHC-class II is necessary, but not sufficient to promote Vδ2 expansion. Our results provide novel insight into the primary cell-specific requirements for human Vδ2 expansion.

γδ-T cells: an unpolished sword in human anti-infection immunity

γδ-T cells represent a small population of immune cells, but play an indispensable role in host defenses against exogenous pathogens, immune surveillance of endogenous pathogenesis and even homeostasis of the immune system. Activation and expansion of γδ-T cells are generally observed in diverse human infectious diseases and correlate with their progression and prognosis. γδ-T cells have both 'innate' and 'adaptive' characteristics in the immune response, and their anti-infection activities are mediated by multiple pathways that are under elaborate regulation by other immune components. In this review, we summarize the current state of the literature and the recent advancements in γδ-T cell-mediated immune responses against common human infectious pathogens. Although further investigation is needed to improve our understanding of the characteristics of different γδ-T cell subpopulations under specific conditions, γδ-T cell-based therapy has great potential for the treatment of infectious diseases.

Phase I/II study of adoptive transfer of γδ T cells in combination with zoledronic acid and IL-2 to patients with advanced renal cell carcinoma

Human Vγ2 Vδ2-bearing T cells have recently received much attention in cancer immunotherapy. In this study, we conducted a phase I/II clinical trial of the adoptive transfer of γδ T cells to patients with advanced renal cell carcinoma. Eleven patients who had undergone nephrectomy and had lung metastasis were enrolled. Peripheral blood γδ T cells obtained from the patients were stimulated ex vivo with 2-methyl-3-butenyl-1-pyrophosphate (2M3B1PP), a synthetic pyrophosphomonoester antigen, and transferred in combination with zoledronic acid (Zol) and teceleukin (recombinant human interleukin-2). Expanded γδ T cells exhibited potent cytotoxic activity against tumor cells in vitro, and the proportion of peripheral blood γδ T cells among CD3(+) cells typically peaked three to 5 days after transfer. Tumor doubling time was prolonged in all 11 patients, and the best overall responses were 1 CR, 5 SD, and 5 PD, as defined based on Response Evaluation Criteria in Solid Tumors (RECIST). Although ten patients developed adverse reactions of grade ≥3, they were likely to have been the result of the concomitant infusion of Zol and IL-2, and most symptoms swiftly reverted to normal during the course of treatment. In conclusion, this clinical trial demonstrated that our regimen for the adoptive transfer of γδ T cells in combination with Zol and IL-2 was well tolerated and that objective clinical responses could be achieved in some patients with advanced renal cell carcinoma.

Current status and future applications of cellular therapies for cancer

Therapies based on the use of autologous immune cells are among the best candidates for cancer immunotherapy. Dendritic cell vaccines have demonstrated very encouraging responses for some solid tumors, while in melanoma autologous T-cell therapies have exceeded 70% objective response rates in selected Phase I trials. However, it is clear that a number of barriers exist to the effective, practical application of these therapies. The aim of this article is to consider modifications to such strategies over the last 3 years and the resultant clinical research in autologous dendritic cell vaccines, T-cell therapy and γδ T-cell therapy for cancer.

Anticancer properties of zoledronic acid

Zoledronic acid effectively reduces/delays skeletal-related events in patients with metastatic disease or skeletal-related cancers. Emerging data suggest that zoledronic acid may also exhibit anticancer properties. Zoledronic acid ± anticancer therapies in animal models inhibits soft-tissue tumor growth, decreases tumor cell proliferation, increases apoptosis, inhibits angiogenesis, alters tumor-associated macrophage function, and enhances immune surveillance. Data from in vitro and pilot studies suggest that zoledronic acid inhibits tumor cell dissemination in bone marrow, and early clinical data show that it may improve disease-related outcomes. Ongoing studies will further elucidate the role of zoledronic acid in cancer patients.

Human γδ T lymphocytes for immunotherapeutic strategies against cancer

γδ T lymphocytes are a numerically small subset of T cells with potent cytotoxic activity against a variety of tumor cells. Human γδ T cells expressing the Vγ9Vδ2 T cell antigen receptor recognize endogenous pyrophosphate molecules that are overproduced in transformed cells. Moreover, the intracellular accumulation of such pyrophosphates is strongly enhanced by aminobisphosphonates used in the treatment of osteoporosis and bone metastasis in certain cancer patients. A new concept of cancer immunotherapy is based on the endogenous activation of γδ T cells with aminobisphosphonates plus low-dose interleukin-2.

Repertoire development and the control of cytotoxic/effector function in human gammadelta T cells

T cells develop into two major populations distinguished by their T cell receptor (TCR) chains. Cells with the alphabeta TCR generally express CD4 or CD8 lineage markers and mostly fall into helper or cytotoxic/effector subsets. Cells expressing the alternate gammadelta TCR in humans generally do not express lineage markers, do not require MHC for antigen presentation, and recognize nonpeptidic antigens. We are interested in the dominant Vgamma2Vdelta2+ T cell subset in human peripheral blood and the control of effector function in this population. We review the literature on gammadelta T cell generation and repertoire selection, along with recent work on CD56 expression and defining a cytotoxic/effector lineage within the phosphoantigen-reactive Vgamma2Vdelta2 cells. A unique mechanism for MHC-independent repertoire selection is linked to the control of effector function that is vital to the role for gammadelta T cells in tumor surveillance. Better understanding of these mechanisms will improve our ability to exploit this population for tumor immunotherapy.