Immunological effects of everolimus in patients with metastatic renal cell cancer

Recurrent Treatment of Refractory Acute Cellular Rejection with Alemtuzumab after Lung Transplantation

We present an exceptional case of a lung transplant recipient successfully treated by multiple courses of alemtuzumab for refractory acute cellular rejection. The patient experienced multiple episodes of acute cellular rejection following the transplantation procedure. Alemtuzumab was initiated as third-line rejection treatment and was repeated six times. Each treatment course resulted in complete recovery of the pulmonary function and depletion of T- and B-lymphocytes and NK cells. The onset of rejection was consistently preceded by the recovery of NK cells, while T- and B-lymphocytes remained depleted. This suggests a rejection process mediated by NK cells. This case contributes to recent research findings suggesting that NK cells play a significant role in acute cellular rejection in lung transplant recipients and stresses the importance to further investigate the role of NK cells in rejection. Furthermore, it demonstrates that acute cellular rejection following lung transplantation can be repeatedly managed by treatment with alemtuzumab. DATA AVAILABILITY STATEMENT: The authors confirm that the data supporting the findings of this study are available within the article.

Targeting mTOR and survivin concurrently potentiates radiation therapy in renal cell carcinoma by suppressing DNA damage repair and amplifying mitotic catastrophe

BACKGROUND

Renal cell carcinoma (RCC) was historically considered to be less responsive to radiation therapy (RT) compared to other cancer indications. However, advancements in precision high-dose radiation delivery through single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) have led to better outcomes and reduced treatment-related toxicities, sparking renewed interest in using RT to treat RCC. Moreover, numerous studies have revealed that certain therapeutic agents including chemotherapies can increase the sensitivity of tumors to RT, leading to a growing interest in combining these treatments. Here, we developed a rational combination of two radiosensitizers in a tumor-targeted liposomal formulation for augmenting RT in RCC. The objective of this study is to assess the efficacy of a tumor-targeted liposomal formulation combining the mTOR inhibitor everolimus (E) with the survivin inhibitor YM155 (Y) in enhancing the sensitivity of RCC tumors to radiation.

EXPERIMENTAL DESIGN

We slightly modified our previously published tumor-targeted liposomal formulation to develop a rational combination of E and Y in a single liposomal formulation (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further investigated how well EY-L sensitizes RCC cell lines and tumors toward radiation and explored the underlying mechanism of radiosensitization.

RESULTS

EY-L outperformed the corresponding single drug-loaded formulations E-L and Y-L in terms of containing primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. EY-L also exhibited significantly higher sensitization of RCC cells towards radiation in vitro than E-L and Y-L. Additionally, EY-L sensitized RCC tumors towards radiation therapy in xenograft and murine RCC models. EY-L mediated induction of mitotic catastrophe via downregulation of multiple cell cycle checkpoints and DNA damage repair pathways could be responsible for the augmentation of radiation therapy.

CONCLUSION

Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy via inhibition of DNA damage repair and a substantial increase in mitotic catastrophe. This combination therapy may find its use in the augmentation of radiation therapy during the treatment of RCC patients.

Targeting mTOR and Survivin Concurrently Potentiates Radiation Therapy in Renal Cell Carcinoma by Suppressing DNA Damage Repair and Amplifying Mitotic Catastrophe

Background

Renal cell carcinoma (RCC) was historically considered to be less responsive to radiation therapy (RT) compared to other cancer indications. However, advancements in precision high-dose radiation delivery through single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) have led to better outcomes and reduced treatment-related toxicities, sparking renewed interest in using RT to treat RCC. Moreover, numerous studies have revealed that certain therapeutic agents including chemotherapies can increase the sensitivity of tumors to RT, leading to a growing interest in combining these treatments. Here, we developed a rational combination of two radiosensitizers in a tumor-targeted liposomal formulation for augmenting RT in RCC. The objective of this study is to assess the efficacy of a tumor-targeted liposomal formulation combining the mTOR inhibitor everolimus (E) with the survivin inhibitor YM155 (Y) in enhancing the sensitivity of RCC tumors to radiation.

Experimental Design

We slightly modified our previously published tumor-targeted liposomal formulation to develop a rational combination of E and Y in a single liposomal formulation (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further investigated how well EY-L sensitizes RCC cell lines and tumors toward radiation and explored the underlying mechanism of radiosensitization.

Results

EY-L outperformed the corresponding single drug-loaded formulations E-L and Y-L in terms of containing primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. EY-L also exhibited significantly higher sensitization of RCC cells towards radiation in vitro than E-L and Y-L. Additionally, EY-L sensitized RCC tumors towards radiation therapy in xenograft and murine RCC models. EY-L mediated induction of mitotic catastrophe via downregulation of multiple cell cycle checkpoints and DNA damage repair pathways could be responsible for the augmentation of radiation therapy.

Conclusion

Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy via inhibition of DNA damage repair and a substantial increase in mitotic catastrophe. This combination therapy may find its use in the augmentation of radiation therapy during the treatment of RCC patients.

Everolimus Acts in Synergy with Vinorelbine to Suppress the Growth of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a challenging cancer to treat, as traditional chemotherapies have shown limited effectiveness. The mammalian target of rapamycin/sirolimus (mTOR) and microtubules are prominent druggable targets for HCC. In this study, we demonstrated that co-targeting mTOR using mTOR inhibitors (everolimus and sirolimus) along with the microtubule inhibitor vinorelbine yielded results superior to those of the monotherapies in HCC PDX models. Our research showed that the vinorelbine arrests cells at the mitotic phase, induces apoptosis, and normalizes tumor blood vessels but upregulates survivin and activates the mTOR/p70S6K/4EBP1 pathway. The addition of the everolimus significantly improved the tumor response to the vinorelbine, leading to improved overall survival (OS) in most tested orthotopic HCC PDX models. The mechanistic investigation revealed that this marked antitumor effect was accompanied by the downregulations of mTOR targets (p-p70S6K, p-4EBP1, and p-S6K); several key cell-cycle regulators; and the antiapoptotic protein survivin. These effects did not compromise the normalization of the blood vessels observed in response to the vinorelbine in the vinorelbine-sensitive PDX models or to the everolimus in the everolimus-sensitive PDX models. The combination of the everolimus and vinorelbine (everolimus/vinorelbine) also promoted apoptosis with minimal toxicity. Given the cost-effectiveness and established effectiveness of everolimus, and especially sirolimus, this strategy warrants further investigation in early-phase clinical trials.

Research progress of ophthalmic preparations of immunosuppressants

Immune ophthalmopathy is a collection of autoimmune eye diseases. Immunosuppressants are drugs that can inhibit the body's immune response. Considering drug side effects such as hepatorenal toxicity and the unique structure of the eye, incorporating immunosuppressants into ophthalmic nanodrug delivery systems, such as microparticles, nanoparticles, liposomes, micelles, implants, and in situ gels, has the advantages of improving solubility, increasing bioavailability, high eye-target specificity, and reducing side effects. This study reviews recent research and applications of this aspect to provide a reference for the development of an ophthalmic drug delivery system.

Inhibition of androgen receptor enhanced the anticancer effects of everolimus through targeting glucose transporter 12

Everolimus was designed as a mammalian target of rapamycin (mTOR) inhibitor. It has been proven as a targeted drug for gastric cancer (GC) therapy. However, long-term treatment with everolimus may cause severe side effects for recipients. Decreasing the dosage and attenuating the associated risks are feasible to promote clinical translation of everolimus. This study aimed to identify the underlying mechanisms of responses to everolimus and develop novel regimens for GC treatment. Our findings proved that there was a significant dose-dependent relationship of everolimus-induced GC cell apoptosis and glycolysis inhibition. Then, we found that a member of glucose transporter (GLUT12) family, GLUT12, was actively upregulated to counteract the anticancer effects of everolimus. GLUT12 might be overexpressed in GC. High expression of GLUT12 might be correlated with tumor progression and short survival time of GC patients. Bioinformatic analysis suggested that GLUT12 might be involved in regulating cancer development and metabolism. The experiments proved that GLUT12 significantly promoted GC growth, glycolysis and impaired the anticancer effects of everolimus. Androgen receptor (AR) is a classical oncogenic factor in many types of cancer. Everolimus elevated GLUT12 expression in an AR-dependent manner. Inhibition of AR activity abrogated the promotive effects on GLUT12 expression. Both in-vitro and in-vivo experiments demonstrated that GLUT12 knockdown augmented anticancer effects of everolimus. Enzalutamide, an AR inhibitor, or AR knockdown was comparable to GLUT12 suppression. This study identified the role of the AR/GLUT12 pathway in the development of poor responses to everolimus. Interference with AR/GLUT12 pathway may serve as a promising approach to promoting the translational application of everolimus in GC therapy.

Treatment Assessment of pNET and NELM after Everolimus by Quantitative MRI Parameters

Assessment of treatment response to targeted therapies such as everolimus is difficult, especially in slow-growing tumors such as NETs. In this retrospective study, 17 patients with pancreatic neuroendocrine tumors (pNETs) and hepatic metastases (NELMs) (42 target lesions) who received everolimus were analyzed. Intralesional signal intensities (SI) of non-contrast T1w, T2w and DCE imaging, and apparent diffusion coefficients (ADCmean and ADCmin) of DWI, were measured on baseline and first follow-up MRI after everolimus initiation. Response assessment was categorized according to progression-free survival (PFS), with responders (R) showing a PFS of ≥11 months. ADCmin of NELMs decreased in Rs whereas it increased in non-responders (NR). Percentual changes of ADCmin and ADCmean differed significantly between response groups (p < 0.03). By contrast, ADC of the pNETs tended to increase in Rs, while there was no change in NRs. Tumor-to-liver (T/L) ratio of T1 SI of NELMs increased in Rs and decreased in NRs, and percentual changes differed significantly between response groups (p < 0.02). T1 SI of the pNETs tended to decrease in Rs and increase in Ns. The quotient of pretherapeutic and posttherapeutic ADCmin values (DADCmin) and length of everolimus treatment showed significant association with PFS in univariable Cox analysis. In conclusion, quantitative MRI, especially DWI, seems to allow treatment assessment of pNETs with NELMs under everolimus. Interestingly, the responding NELMs showed decreasing ADC values, and there might be an opposite effect on ADC and T1 SI between NELMs and pNETs.

Administration of Nivolumab in Metastatic Renal Cell Cancer Following Treatment With mTOR Inhibitors

BACKGROUND/AIM

Immunotherapy with checkpoint inhibitors is currently considered a cornerstone of metastatic renal clear cell cancer (mRCC) therapy. Despite the general improvement in the survival of patients with mRCC, there are some clinical situations that have not been specifically evaluated in clinical trials, such as the use of everolimus before nivolumab.

PATIENTS AND METHODS

We performed a retrospective analysis evaluating the efficacy of nivolumab in the real-world setting, including a subset of patients with previous mTOR inhibitor therapy.

RESULTS

From a total of 56 patients, 25 were pre-treated with everolimus before receiving nivolumab. The overall progression-free survival (PFS), overall survival (OS), and objective response rate were 10.3, 21.3 months, and 34%, respectively. There were no statistically significant differences in patients who were or were not pre-treated with everolimus.

CONCLUSION

mRCC patients should be treated with checkpoint inhibitors and prior use of mTOR inhibitors should not be a definitive exclusion criterium.

Combining mTOR Inhibitors and T Cell-Based Immunotherapies in Cancer Treatment

mTOR regulates several processes that control tumor development, including cancer cell growth, angiogenesis and the immune response to tumor. Accordingly, mTOR inhibitors have been thoroughly explored in cancer therapy but have failed to provide long-lasting anticancer benefits. Several resistance mechanisms that counteract the antitumor effect of mTOR inhibitors have been identified and have highlighted the need to use mTOR inhibitors in combination therapies. In this context, emerging evidence has demonstrated that mTOR inhibitors, despite their immunosuppressive properties, provide anticancer benefits to immunotherapies. In fact, mTOR inhibitors also display immunostimulatory effects, in particular by promoting memory CD8+ T cell generation. Hence, mTOR inhibitors represent a therapeutic opportunity to promote antitumor CD8 responses and to boost the efficacy of different modalities of cancer immunotherapy. In this context, strategies to reduce the immunosuppressive activity of mTOR inhibitors and therefore to shift the immune response toward antitumor immunity will be useful. In this review, we present the different classes of mTOR inhibitors and discuss their effect on immune cells by focusing mainly on CD8+ T cells. We further provide an overview of the different preclinical studies that investigated the anticancer effects of mTOR inhibitors combined to immunotherapies.

Mechanistic Target of Rapamycin Inhibitors in Renal Cell Carcinoma: Potential, Limitations, and Perspectives

Several elements highlight the importance of the mechanistic target of rapamycin (mTOR) in the biology of renal cell carcinoma (RCC). mTOR signaling pathway is indeed frequently activated in RCC, inducing cancer cell proliferation and survival. In addition, mTOR promotes tumor angiogenesis and regulates the expression of hypoxia-inducible factors that play an important role in a subset of RCC. Despite mTOR protumorigenic effects, mTOR inhibitors have failed to provide long-lasting anticancer benefits in RCC patients, highlighting the need to readdress their role in the treatment of RCC. This review aims to present the rationale and limitations of targeting mTOR in RCC. Future roles of mTOR inhibitors in the treatment of RCC are also discussed, in particular in the context of immunotherapies.

Baseline effector cells predict response and NKT cells predict pulmonary toxicity in advanced breast cancer patients treated with everolimus and exemestane

BACKGROUND

The mTOR inhibitor everolimus used in cancer has immune-modulating effects, potentially contributing to an antitumor response but also leading to pulmonary toxicity. We studied the association of immunological cell subsets with antitumor response and pulmonary toxicity in breast cancer patients treated with everolimus plus exemestane.

METHODS

In this exploratory analysis, peripheral blood mononuclear cells (PBMCs) were collected at baseline and 14, 35, 60, and 90 days after start of treatment, and at the moment of pulmonary toxicity. The percentage and absolute number of T-cells, B-cells, NK-cells, monocytes and numerous subtypes were measured in peripheral blood using flow cytometric analysis and were compared using a (paired) t-test.

RESULTS

From 20 patients, a total of 89 samples were collected. At baseline, responders versus non-responders had 0.86% versus 0.32% CD4+ effector cells (CD45RA+CD27-) (p = 0.1266) and non-response could be predicted with 0.71 sensitivity and 0.82 specificity. Patients who developed pulmonary toxicity compared to patients without pulmonary toxicity had relatively more NKT-cells at baseline (6.0% versus 1.3%, p = 0.0068, 59 k versus 12 k * 10⁹/l, p = 0.0081) and at the moment of toxicity (5.2% versus 1.2%, p = 0.0106 and 47 k versus 16 k * 10⁹/l, p = 0.0466). Baseline percentage NKT cells predicted pulmonary toxicity with 0.78 sensitivity and 1.0 specificity.

CONCLUSIONS

Our results suggest that baseline CD4+ effector cells may be predictive of antitumor responses and baseline NKT cells may be predictive of pulmonary toxicity. These results warrant further validation.

Roles of the Dynamic Tumor Immune Microenvironment in the Individualized Treatment of Advanced Clear Cell Renal Cell Carcinoma

Immune checkpoint inhibitors (ICIs) are currently a first-line treatment option for clear cell renal cell carcinoma (ccRCC). However, recent clinical studies have shown that a large number of patients do not respond to ICIs. Moreover, only a few patients achieve a stable and durable response even with combination therapy based on ICIs. Available studies have concluded that the response to immunotherapy and targeted therapy in patients with ccRCC is affected by the tumor immune microenvironment (TIME), which can be manipulated by targeted therapy and tumor genomic characteristics. Therefore, an in-depth understanding of the dynamic nature of the TIME is important for improving the efficacy of immunotherapy or combination therapy in patients with advanced ccRCC. Here, we explore the possible mechanisms by which the TIME affects the efficacy of immunotherapy and targeted therapy, as well as the factors that drive dynamic changes in the TIME in ccRCC, including the immunomodulatory effect of targeted therapy and genomic changes. We also describe the progress on novel therapeutic modalities for advanced ccRCC based on the TIME. Overall, this review provides valuable information on the optimization of combination therapy and development of individualized therapy for advanced ccRCC.

Combination Strategies to Improve Targeted Radionuclide Therapy

In recent years, targeted radionuclide therapy (TRT) has emerged as a promising strategy for cancer treatment. In contrast to conventional radiotherapy, TRT delivers ionizing radiation to tumors in a targeted manner, reducing the dose that healthy tissues are exposed to. Existing TRT strategies include the use of 177Lu-DOTATATE, 131I-metaiodobenzylguanidine, Bexxar, and Zevalin, clinically approved agents for the treatment of neuroendocrine tumors, neuroblastoma, and non-Hodgkin lymphoma, respectively. Although promising results have been obtained with these agents, clinical evidence acquired to date suggests that only a small percentage of patients achieves complete response. Consequently, there have been attempts to improve TRT outcomes through combinations with other therapeutic agents; such strategies include administering concurrent TRT and chemotherapy, and the use of TRT with known or putative radiosensitizers such as poly(adenosine diphosphate ribose) polymerase and mammalian-target-of-rapamycin inhibitors. In addition to potentially achieving greater therapeutic effects than the respective monotherapies, these strategies may lead to lower dosages or numbers of cycles required and, in turn, reduce unwanted toxicities. As of now, several clinical trials have been conducted to assess the benefits of TRT-based combination therapies, sometimes despite limited preclinical evidence being available in the public domain to support their use. Although some clinical trials have yielded promising results, others have shown no clear survival benefit from particular combination treatments. Here, we present a comprehensive review of combination strategies with TRT reported in the literature to date and evaluate their therapeutic potential.

Preparation and study of two kinds of ophthalmic nano-preparations of everolimus

Objective: To prepare everolimus nanoformulations and increase their solubility to suit their application in the eye. Methods: The everolimus micelles was prepared by thin film dispersion method using Tween-80 (P80) and polyoxyethylene stearate (P40S) as carriers. In addition, the everolimus nanosuspension was prepared by injection method using poloxamer 407 (P407), hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) as stabilizers. It was characterized in terms of particle size, PDI and encapsulation efficiency or drug loading. The in vitro release and in vitro rabbit scleral permeability characteristics were investigated, and the pharmacokinetics of anterior chamber drug in rabbit eyes were studied. Results: The average particle size of the micelles was (8.74 ± 0.21) nm, the encapsulation efficiency and drug loading were (90.12 ± 1.18)% and (2.14 ± 0.028)%, while the average particle size of the nanosuspension was (156.47 ± 1.10) nm, and the drug loading was (16.51 ± 0.21)%, respectively. Both in vitro release and rabbit scleral permeation models were consistent with the Higuchi equation. The pharmacokinetic experiments of aqueous humor showed that area under the curve of everolimus nanosuspension was about 3 times higher than that of micelles. Micelles could be achieved in the eye and maintained for a long time. Conclusion: The preparation of everolimus micelles or nanosuspension for eye are suitable for ocular administration and expected to be new dosage form for corneal transplantation immunological rejection or other ocular disease.

Different immunological effects of the molecular targeted agents sunitinib, everolimus and temsirolimus in patients with renal cell carcinoma

Treatment with molecular targeted agents together with immune checkpoint inhibitors will most likely improve the efficacy of current cancer immunotherapy. Because molecular targeted agents not only directly affect cancer cells, but also influence immune cells and modulate the tumor microenvironment, a better understanding of the overall immunological effects of these drugs will contribute to the rational design of combination therapies. Therefore, this study performed extensive immune monitoring of patients' peripheral blood mononuclear cells (PBMCs) to investigate the immunological effects of the molecular targeted agents sunitinib, everolimus and temsirolimus, which have been widely used for the treatment of renal cell carcinoma (RCC). Immunophenotyping and functional analysis of PBMCs revealed that these molecular targeted agents exerted different immunological effects on patients with RCC. Sunitinib decreased the percentage of early‑stage myeloid‑derived suppressor cells (eMDSCs) and increased natural killer cells, but did not affect the phenotypes and effector functions of CD4+ or CD8+ T cells. Everolimus decreased effector regulatory T cells, but also decreased IL‑2‑producing CD4+ T cells and increased dysfunctional CD8+ T cells. Conversely, temsirolimus decreased programmed cell death protein 1+CD8+ T cells and eMDSCs, but increased interferon‑γ and tumor necrosis factor‑α double producers at the same time as decreasing dysfunctional CD8+ T cells, albeit not significantly. In conclusion, although everolimus and temsirolimus are mTOR inhibitors, their effects on overall T‑cell functions are very different. Therefore, although it may increase the risk of immune‑related toxicity, temsirolimus is expected to offer the best outcome when combined with other immunomodulators for the development of cancer immunotherapy.

NK Cell-Based Immunotherapy in Renal Cell Carcinoma

Natural killer (NK) cells are cytotoxic lymphocytes that are able to kill tumor cells without prior sensitization. It has been shown that NK cells play a pivotal role in a variety of cancers, highlighting their relevance in tumor immunosurveillance. NK cell infiltration has been reported in renal cell carcinoma (RCC), the most frequent kidney cancer in adults, and their presence has been associated with patients’ survival. However, the role of NK cells in this disease is not yet fully understood. In this review, we summarize the biology of NK cells and the mechanisms through which they are able to recognize and kill tumor cells. Furthermore, we discuss the role that NK cells play in renal cell carcinoma, and review current strategies that are being used to boost and exploit their cytotoxic capabilities.

Synchronous inhibition of mTOR and VEGF/NRP1 axis impedes tumor growth and metastasis in renal cancer

Clear cell renal cell carcinoma (ccRCC) is known for its highly vascular phenotype which is associated with elevated expression of vascular endothelial growth factor A (VEGF), also known as vascular permeability factor (VPF). Accordingly, VEGF has been an attractive target for antiangiogenic therapies in ccRCC. Two major strategies have hitherto been utilized for VEGF-targeted antiangiogenic therapies: targeting VEGF by antibodies, ligand traps or aptamers, and targeting the VEGF receptor signaling via antibodies or small-molecule tyrosine-kinase inhibitors (TKIs). In the present article we utilized two entirely different approaches: targeting mammalian target of rapamycin (mTOR) pathway that is known to be involved in VEGF synthesis, and disruption of VEGF/Neuroplin-1 (NRP1) axis that is known to activate proangiogenic and pro-tumorigenic signaling in endothelial and tumor cells, respectively. Everolimus (E) and a small-molecule inhibitor EG00229 (G) were used for the inhibition of mTOR and the disruption of VEGF/NRP1 axis, respectively. We also exploited a liposomal formulation decorated with a proprietary tumor-targeting-peptide (TTP) to simultaneously deliver these two agents in a tumor-targeted manner. The TTP-liposomes encapsulating both Everolimus and EG00229 (EG-L) demonstrated higher in vitro and in vivo growth retardation than the single drug-loaded liposomes (E-L and G-L) in two different ccRCC models and led to a noticeable reduction in lung metastasis in vivo. In addition, EG-L displayed remarkable inhibition of tumor growth in a highly aggressive syngeneic immune-competent mouse model of ccRCC developed in Balb/c mice. Taken together, this study demonstrates an effective approach to achieve improved therapeutic outcome in ccRCC.

Autologous tumor cell vaccination combined with systemic CpG-B and IFN-α promotes immune activation and induces clinical responses in patients with metastatic renal cell carcinoma: a phase II trial

Background

In this study the toxicity and efficacy of an irradiated autologous tumor cell vaccine (ATV) co-injected with a class-B CpG oligodeoxynucleotide (CpG-B) and GM-CSF, followed by systemic CpG-B and IFN-α administration, were examined in patients with metastatic renal cell carcinoma (mRCC).

Methods

A single-arm Phase II trial was conducted, in which patients with mRCC were intradermally injected with a minimum of three whole-cell vaccines containing 0.7–1.3 × 107 irradiated autologous tumor cells (ATC), admixed with 1 mg CpG-B and 100 µg GM-CSF, followed by bi-weekly s.c. injections with 8 mg CpG-B and s.c. injections with 6 MU IFN-α three times per week.

Results

Fifteen patients were treated according to the protocol. Treatment was well tolerated. Objective clinical responses occurred in three patients, including one long-term complete response. Disease stabilization occurred in another three patients. Positive delayed type hypersensitivity (DTH) responses to ATC were absent before treatment but present in 13 out of 15 patients during treatment. Immune monitoring revealed activation of plasmacytoid dendritic cells, non-classical monocytes and up-regulation of both PD-1 and CTLA4 on effector T cells upon treatment. Moreover, a pre-existing ex vivo IFN-γ response to ATC was associated with clinical response.

Conclusions

ATV combined with systemic CpG-B and IFN-α is tolerable, safe, immunogenic and able to elicit anti-tumor responses in patients with mRCC. Immune activation and treatment-induced up-regulation of PD-1 and CTLA4 on circulating T cells further suggest an added benefit of combining this approach with immune checkpoint blockade [added]

Metronomic cyclophosphamide attenuates mTOR-mediated expansion of regulatory T cells, but does not impact clinical outcome in patients with metastatic renal cell cancer treated with everolimus

INTRODUCTION

Metastatic renal cell cancer (mRCC) patients have a median overall survival (mOS) of approximately 28 months. Until recently, mammalian target of rapamycin (mTOR) inhibition with everolimus was the standard second-line treatment regimen for mRCC patients, improving median progression-free survival (mPFS). Treatment with everolimus supports the expansion of immunosuppressive regulatory T cells (Tregs), which exert a negative effect on antitumor immune responses. In a phase 1 dose-escalation study, we have recently demonstrated that a low dose of 50 mg oral cyclophosphamide once daily can be safely combined with everolimus in mRCC patients and prevents the everolimus-induced increase in Tregs.

MATERIALS AND METHODS

In a multicenter phase 2 study, performed in patients with mRCC not amenable to or progressive on a vascular endothelial growth factor (VEGF)-receptor tyrosine kinase inhibitor (TKI) containing treatment regimen, we assessed whether the addition of this metronomic dosing schedule of cyclophosphamide to therapy with everolimus could result in an improvement of progression-free survival (PFS) after 4 months of treatment.

RESULTS

Though results from this study confirmed that combination treatment effectively lowered circulating levels of Tregs, addition of cyclophosphamide did not improve the PFS rate at 4 months. For this reason, the study was abrogated at the predefined interim analysis.

CONCLUSION

Although the comprehensive immunomonitoring analysis performed in this study provides relevant information for the design of future immunotherapeutic approaches, the addition of metronomic cyclophosphamide to mRCC patients receiving everolimus cannot be recommended.

mTOR Signaling pathway as a master regulator of memory CD8+ T-cells, Th17, and NK cells development and their functional properties

The mammalian target of rapamycin (mTOR) is a member of the evolutionary phosphatidylinositol kinase-related kinases (PIKKs). mTOR plays a pivotal role in the regulation of diverse aspects of cellular physiology such as body metabolism, cell growth, protein synthesis, cell size, autophagy, and cell differentiation. Immunologically, mTOR has a fundamental part in controlling and shaping diverse functions of innate and adaptive immune cells, in particular, T-cell subsets differentiation, survival, and metabolic reprogramming to ultimately regulate the fate of diverse immune cell types. Researchers report that rapamycin, a selective mTOR inhibitor, and immunosuppressive agent, has surprising immunostimulatory effects on inducing both quantitative and qualitative aspects of virus-specific memory CD8⁺ T-cells differentiation and homeostasis in a T-cell-intrinsic manner. The mTOR signaling pathway also plays a critical role in dictating the outcome of regulatory T cells (Treg), T helper 17 (Th17) cells, and natural killer (NK) cells proliferation and maturation, as well as the effector functions and cytotoxic properties of NK cells. Manipulation of mTOR activity is a critical therapeutic approach for pharmacological agents that seek to inhibit mTOR. This approach should enhance specific memory CD8 ⁺ T-cells responses and induce fully functional effector properties of NK cells to provoke their antitumor and antiviral activities.

Phase 1 study of everolimus and low-dose oral cyclophosphamide in patients with metastatic renal cell carcinoma

mTOR inhibitors are frequently used in the treatment of metastatic renal cell cancer (mRCC). mTOR regulates cell growth, proliferation, angiogenesis, and survival, and additionally plays an important role in immune regulation. Since mTOR inhibitors were shown to benefit immunosuppressive regulatory T-cell (Treg) expansion, this might suppress antitumor immune responses. Metronomic cyclophosphamide (CTX) was shown to selectively deplete Tregs. This study was, therefore, designed to determine the optimal dosage and schedule of CTX when combined with everolimus to prevent this potentially detrimental Treg expansion. In this national multi-center phase I study, patients with mRCC progressive on first line anti-angiogenic therapy received 10 mg everolimus once daily and were enrolled into cohorts with different CTX dosages and schedules. Besides immune monitoring, adverse events and survival data were monitored. 40 patients, 39 evaluable, were treated with different doses and schedules of CTX. Combined with 10 mg everolimus once daily, the optimal Treg depleting dose and schedule of CTX was 50 mg CTX once daily. 23 (59%) patients experienced one or more treatment-related ≥ grade 3 toxicity, mostly fatigue, laboratory abnormalities and pneumonitis. The majority of the patients achieved stable disease, two patients a partial response. Median PFS of all cohorts was 3.5 months. In conclusion, the optimal Treg depleting dose and schedule of CTX, when combined with everolimus, is 50 mg once daily. This combination leads to acceptable adverse events in comparison with everolimus alone. Currently, the here selected combination is being evaluated in a phase II clinical trial. TRIAL REGISTRATION: NCT01462214.

The effect of everolimus and low-dose cyclophosphamide on immune cell subsets in patients with metastatic renal cell carcinoma: results from a phase I clinical trial

For the treatment of metastatic renal cell cancer several strategies are used among which the mTOR inhibitor everolimus. As mTOR plays an important role in the immune system, e.g., by controlling the expression of the transcription factor FoxP3 thereby regulating regulatory T cells (Tregs), it plays a key role in the balance between tolerance and inflammation. Previous reports showed stimulatory effects of mTOR inhibition on the expansion of Tregs, an effect that can be considered detrimental in terms of cancer control. Since metronomic cyclophosphamide (CTX) was shown to selectively deplete Tregs, a phase 1 clinical trial was conducted to comprehensively investigate the immune-modulating effects of several dosages and schedules of CTX in combination with the standard dose of everolimus, with the explicit aim to achieve selective Treg depletion. Our data show that 50 mg of CTX once daily and continuously administered, in combination with the standard dose of 10 mg everolimus once daily, not only results in depletion of Tregs, but also leads to a reduction in MDSC, a sustained level of the CD8⁺ T-cell population accompanied by an increased effector to suppressor ratio, and reversal of negative effects on three peripheral blood DC subsets. These positive effects on the immune response may contribute to improved survival, and therefore this combination therapy is further evaluated in a phase II clinical trial.