Everolimus and mycophenolate mofetil sensitize human pancreatic cancer cells to gemcitabine in vitro: a novel adjunct to standard chemotherapy?

Impact of Non-steroidal Anti-inflammatory Drugs, Glucocorticoids, and Disease-Modifying Anti-Rheumatic Drugs on Cancer Response to Immune Checkpoint Inhibitor Therapy

Immune checkpoint inhibitor (ICI) therapy for advanced malignancies often leads to off-target adverse events. Rheumatic immune-related adverse events can often linger beyond the duration of ICI therapy and sometimes requires the use of immunomodulator therapy. A key question, therefore, is if the commonly used therapies affect cancer outcomes. In this review, the authors summarize the state of the data as it currently stands, taking into consideration the limitations of the various source studies. The most information is known about glucocorticoids, which appear to be harmful especially when used early and at high doses.

Targeting KRAS for the potential treatment of pancreatic ductal adenocarcinoma: Recent advancements provide hope (Review)

Kirsten rat sarcoma viral oncogene homolog (KRAS) is one of the most frequently mutated oncogenes in solid tumors. More than 90% of pancreatic ductal adenocarcinoma (PDAC) are driven by mutations in the KRAS gene, suggesting the importance of targeting this oncogene in PDAC. Initial efforts to target KRAS have been unsuccessful due to its small size, high affinity for guanosine triphosphate/guanosine diphosphate, and lack of distinct drug‑binding pockets. Therefore, much of the focus has been directed at inhibiting the activation of major signaling pathways downstream of KRAS, most notably the PI3K/AKT and RAF/MAPK pathways, using tyrosine kinase inhibitors and monoclonal antibodies. While preclinical studies showed promising results, clinical data using the inhibitors alone and in combination with other standard therapies have shown limited practicality, largely due to the lack of efficacy and dose‑limiting toxicities. Recent therapeutic approaches for KRAS‑driven tumors focus on mutation‑specific drugs such as selective KRASG12C inhibitors and son of sevenless 1 pan‑KRAS inhibitors. While KRASG12C inhibitors showed great promise against patients with non‑small cell lung cancer (NSCLC) harboring KRASG12C mutations, they were not efficacious in PDAC largely because the major KRAS mutant isoforms in PDAC are G12D, G12V, and G12R. As a result, KRASG12D and pan‑KRAS inhibitors are currently under investigation as potential therapeutic options for PDAC. The present review summarized the importance of KRAS oncogenic signaling, challenges in its targeting, and preclinical and clinical targeted agents including recent direct KRAS inhibitors for blocking KRAS signaling in PDAC.

Case report: Responses to the combination of gemcitabine with sirolimus in two patients with TSC-mutated sarcomas

TSC-mutated sarcomas are rare molecular and histologic types of sarcoma. Due to the presence of their specific oncogenic driver mutation, these sarcomas are particularly sensitive to mTOR inhibitors. Recently, nab-sirolimus, an albumin-bound mTOR inhibitor, was approved by the Food and Drug Administration (FDA) for PEComas, which harbor a TSC mutation, and this drug remains the only FDA-approved systemic treatment for these tumors. We report on two cases of patients with TSC-mutated sarcomas who experienced significant responses to the combination of gemcitabine and sirolimus, after progression on prior gemcitabine-based chemotherapy and single agent mTOR inhibition with nab-sirolimus. Preclinical and clinical data support rationale for a synergistic effect of the combination. This combination may represent a valid therapeutic option after failure of nab-sirolimus in these patients, with no standard-of-care treatment options.

Mycophenolic acid and cancer risk in solid organ transplant recipients: Systematic review and meta-analysis

AIM

Mycophenolic acid (MPA) is an immunosuppressive drug commonly used for prophylaxis of graft rejection in solid organ transplant recipients. The main concern with the prolonged use of immunosuppressive drugs is the risk of developing cancer. However, it remains unclear whether the immunosuppressive regimens containing MPA confer an increased degree of cancer risk. The present study aimed to determine the association between MPA exposure and the incidence of cancer in solid organ transplant recipients.

METHODS

A systematic search was performed on the PubMed, EMBASE and Cochrane Library databases. Relevant articles that had findings on the incidence (or event) of cancer in cohorts with and without MPA exposure were retrieved for data extraction. A meta-analysis was conducted by means of the random-effects model, and the relative risk (RR) and its 95% confidence interval (95% CI) were used as a summary effect measure.

RESULTS

A total of 39 studies were eligible for inclusion, with 32 studies that enabled meta-analysis. MPA exposure was significantly associated with a lower risk of cancer when compared to azathioprine exposure (RR = 0.66, 95% CI = 0.53-0.81, P < .001) or no exposure to any additional treatments (RR = 0.85, 95% CI = 0.73-0.99, P = .04). There was no significant difference in cancer risk for the comparison between MPA exposure and mammalian target of rapamycin (mTOR) inhibitor exposure (RR = 1.54, 95% CI = 0.96-2.46, P = .07).

CONCLUSIONS

MPA exposure was not associated with an increased risk of cancer and may even be associated with a lower risk of cancer when compared to azathioprine or no treatment.

Therapeutic potential and molecular mechanisms of mycophenolic acid as an anticancer agent

Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil (MMF), an immunosuppressive drug approved for the prophylaxis of allograft rejection in transplant recipients. Recent advances in the role of the type II isoform of inosine-5'-monophosphate dehydrogenase (IMPDH2) in the tumorigenesis of various types of cancer have called for a second look of MPA, the first IMPDH2 inhibitor discovered a hundred years ago, to be repurposed as an anticancer agent. Over a half century, a number of in vitro and in vivo experiments have consistently shown anticancer activity of MPA against several cell lines obtained from different malignancies and murine models. However, a few clinical trials have been conducted to investigate its anticancer activity in humans, and most of which have shown unsatisfactory results. Understanding of available evidence and underlying mechanism of action is a key step to be done so as to facilitate further investigations of MPA to reach its full therapeutic potential as an anticancer agent. This article provides a comprehensive review of non-clinical and clinical evidence available to date, with the emphasis on the molecular mechanism of action in which MPA exerts its anticancer activities: induction of apoptosis, induction of cell cycle arrest, and alteration of tumor microenvironment. Future perspective for further development of MPA to be an anticancer agent is extensively discussed, with the aim of translating the anticancer property of MPA from bench to bedside.

Everolimus for the treatment of advanced pancreatic ductal adenocarcinoma (PDAC)

Introduction: PDAC is a lethal malignancy with a clear unmet need; almost all patients fail 1st, 2nd, and 3rd line multi-agent cytotoxic chemotherapy. The mammalian target of rapamycin (mTOR) has been identified as a key signaling node enhancing tumor survival and drug resistance in PDAC; hence, it is considered a promising therapeutic target. Areas covered: We comprehensively reviewed the evidence from preclinical and phase I and II clinical trials, based on the authors'clinical experience and a PubMed, Cochrane library, Embase, and Google Scholar search everolimus + pancreatic cancer. Expert opinion: Everolimus has not demonstrated efficacy in PDAC; however, an mTOR inhibitor in combination with stroma-targeted therapies may be a promising area to explore in clinical trials.

Phase IB Study of Induction Chemotherapy With XELOX, Followed by Radiation Therapy, Carboplatin, and Everolimus in Patients With Locally Advanced Esophageal Cancer

PURPOSE

Preclinical studies have shown synergy between everolimus, an mTOR inhibitor, radiation, and platinum agents. We conducted a phase IB trial to determine the recommended phase II dose of everolimus with carboplatin and radiation.

MATERIALS AND METHODS

Patients with stage II/III esophageal cancer were enrolled. Following 2 cycles of Capecitabine/Oxaliplatin (XELOX), patients with no disease progression, received 50.4 Gy in 28 fractions and concurrent weekly carboplatin (area under the curve=2), with escalating doses of everolimus. A standard 3+3 dose escalation design was used.

RESULTS

Nineteen patients were enrolled. Two patients were screen failures and 4 were removed due to poor tolerance to XELOX (n=2) or disease progression (n=2). All treated patients had adenocarcinoma. Median age was 58 (44 to 71 y) and 85% were male patients. One patient at dose level 1 was replaced due to ongoing anxiety. One of 6 patients had a dose-limiting toxicity of bowel ischemia that was fatal. At dose level 2, two of 6 patients had a dose-limiting toxicity (fever with neutropenia and nausea). The recommended phase II dose of everolimus was 2.5 mg QOD. Grade ≥3 toxicities included lymphopenia (11%), nausea (10%), low white blood cell (8.0%) vomiting (5.5%), decreased neutrophils (4.0%). All patients achieved an R0 resection with a pathologic response rate of 40% and a pathologic complete response (ypCR) rate of 23%. The 2-year progression-free survival and overall survival were 50% and 49.6%, respectively.

CONCLUSIONS

The recommended phase II dose of everolimus with concurrent weekly carboplatin and radiation is 2.5 mg QOD.

The combination of everolimus and zoledronic acid increase the efficacy of gemcitabine in a mouse model of pancreatic adenocarcinoma

Background

Gemcitabine is a standard treatment for pancreatic adenocarcinoma. Many mechanisms are involved in gemcitabine resistance, such as reduced expression of the human equilibrative nucleoside transporter 1 (hENT1) membrane transporter, deoxycytidine kinase deficiency, and changes in the signal transmission of mitogen-activity protein kinase (MAPK) and the phosphoinositide 3-kinase (PI3K) pathways.

Aim

To evaluate the anti-tumor efficiency of blocking signaling pathways using combined action of gemcitabine, everolimus and zoledronic acid versus gemcitabine alone in a mouse subcutaneous xenograft.

Methods

Implantations of two human pancreatic adenocarcinoma cells lines (PANC1, K-ras mutated and gemcitabine-resistant; and BxPc3, wild-type K-ras and gemcitabine-sensitive) were performed on male athymic nude mice. The mice received different treatments: gemcitabine, gemcitabine plus everolimus, everolimus, gemcitabine plus zoledronic acid, everolimus plus zoledronic acid, or gemcitabine plus everolimus and zoledronic acid, for 28 days. We measured the tumor volume and researched the expression of the biomarkers involved in the signaling pathways or in gemcitabine resistance.

Results

In wild-type K-ras tumors, the combinations of gemcitabine plus everolimus; zoledronic acid plus everolimus; and gemcitabine plus zoledronic acid and everolimus slowed tumor growth, probably due to caspase-3 overexpression and reduced Annexin II expression. In mutated K-ras tumors, gemcitabine plus everolimus and zoledronic acid, and the combination of zoledronic acid and everolimus, decreased tumor volume as compared to gemcitabine alone, inhibiting the ERK feedback loop induced by everolimus.

Conclusion

The combination of zoledronic acid and everolimus has an antitumor effect and could increase gemcitabine efficacy.

Single Arm Phase I/II Study of Everolimus and Intravesical Gemcitabine in Patients with Primary or Secondary Carcinoma In Situ of the Bladder who failed Bacillus Calmette Guerin (NCT01259063)

Background: Standard treatment for BCG-refractory urothelial cancer is radical cystectomy. Identification of active agents is clearly warranted.

Objective: To determine a safe dose of oral everolimus in combination with standard intravesical gemcitabine and to evaluate the efficacy of this combination.

Methods: Patients with carcinoma in situ refractory to intravesical bacillus Calmette-Guérin and refusing cystectomy were eligible. Patients in the phase I part of the trial received one of three dose levels of oral everolimus. Patients also received a fixed dose of intravesical gemcitabine. Maintenance everolimus was given for 12 months in patients achieving a complete response confirmed by cystoscopy and cytology. Patients in phase II received continuous everolimus administered at 10 mg daily with intravesical gemcitabine followed by everolimus maintenance for 12 months of total therapy. The enrollment goal for the phase II was 33 patients.

Results: 14 patients were enrolled in phase I of the trial. 23 patients were enrolled in phase II of the trial and 19 were evaluable for primary and secondary endpoints. Four patients withdrew consent prior to treatment initiation. Of the 19 patients evaluable for response, 3 (16%, 95% confidence interval [CI] 3% – 40%) were disease free at 1 yr. The probability of RFS was 20% (95% CI 5% – 42%) at 12 months. Ten patients out of 19 had grade 3 or greater toxicity events. Seven withdrew consent or were taken off study.

Conclusions: Many patients withdrew, and enrollment was halted. Continuous oral everolimus plus intravesical gemcitabine was not well tolerated in this patient population where the threshold for tolerability is low.

A Review of the Potential Utility of Mycophenolate Mofetil as a Cancer Therapeutic

Tumor cells adapt to their high metabolic state by increasing energy production. To this end, current efforts in molecular cancer therapeutics have been focused on signaling pathways that modulate cellular metabolism. However, targeting such signaling pathways is challenging due to heterogeneity of tumors and recurrent oncogenic mutations. A critical need remains to develop antitumor drugs that target tumor specific pathways. Here, we discuss an energy metabolic pathway that is preferentially activated in several cancers as a potential target for molecular cancer therapy. In vitro studies have revealed that many cancer cells synthesize guanosine triphosphate (GTP), via the de novo purine nucleotide synthesis pathway by upregulating the rate limiting enzyme of this pathway, inosine monophosphate dehydrogenase (IMPDH). Non-proliferating cells use an alternative purine nucleotide synthesis pathway, the salvage pathway, to synthesize GTP. These observations pose IMPDH as a potential target to suppress tumor cell growth. The IMPDH inhibitor, mycophenolate mofetil (MMF), is an FDA-approved immunosuppressive drug. Accumulating evidence shows that, in addition to its immunosuppressive effects, MMF also has antitumor effects via IMPDH inhibition in vitro and in vivo. Here, we review the literature on IMPDH as related to tumorigenesis and the use of MMF as a potential antitumor drug.

Molecular biology of adenocarcinoma of the pancreatic duct, current state and future therapeutic avenues

Pancreatic adenocarcinoma is a lethal disease; currently surgery offers five years survival of less than 5%. Any improvement in the outcome is likely to be through novel therapeutic agents that will target the genetic machinery of the cell. Knowledge of genetic alterations in the process of carcinogenesis is expanding rapidly, the targeted therapy, however, is progressing slowly. Pancreatic adenocarcinoma displays a variety of molecular changes that evolve exponentially with time and lend the cancer cells their ability not only to survive, but also to invade the surrounding tissues and metastasise to distant sites. These changes involve genetic alteration in oncogenes, cancer suppressor genes, changes in cell cycle, pathways of apoptosis and also changes in epithelial to mesenchymal transition. Monotherapeutic targeted agents seem(s) to have limited effect on cancer cells. The near future is likely to show an improvement in the treatment outcome, which is likely to be a result of the combination of targeted agents with surgery and chemotherapy.

Everolimus enhances gemcitabine-induced cytotoxicity in bladder-cancer cell lines

The purpose of this study was to determine whether everolimus, a rapamycin derivative, might significantly enhance the cytotoxicity of gemcitabine, an antitumor drug, in two human bladder-cancer cell lines. Human bladder-cancer T24 and 5637 cells were incubated with gemcitabine and everolimus in a range of concentrations either alone or in combination for 72 h. Flow cytometry, comet assay, MTT method and optical microscopy were used to assess cell proliferation, cell cycle, DNA damage, and morphological alterations. Gemcitabine exerted an inhibitory effect on T24 and 5637 cell proliferation, in a concentration-dependent manner. Everolimus significantly reduced proliferation of 5637 bladder cancer cells (IC₃₀) at 1 μM), whereas T24 demonstrated marked resistance to everolimus treatment. A significant antiproliferative effect was obtained combining gemcitabine (100 nM) with everolimus (0.05-2 μM) with an arrest of cell cycle at S phase. Furthermore, an increase in frequency of DNA damage, apoptotic bodies, and apoptotic cells was observed when T24 and 5637 cancer cells were treated simultaneously with both drugs. Data show that in vitro combination produced a more potent antiproliferative effect when compared with single drugs.

Phase I clinical and pharmacokinetic study of RAD001 (everolimus) administered daily to Japanese patients with advanced solid tumors

Objective

To determine the pharmacokinetics and safety of RAD001 (everolimus) in Japanese patients with advanced solid tumors.

Methods

An open-label, non-randomized, dose-escalation Phase I study of RAD001 administered continuously once daily in a 28-day cycle was performed. The study had a ‘3 + 3’ design, with three patients recruited to each of three successive cohorts treated with RAD001 at 2.5, 5.0 or 10.0 mg/day.

Results

The pharmacokinetics of RAD001 in Japanese patients were similar to those previously determined in Caucasians. The drug safety profile was consistent with that of a mammalian target of rapamycin inhibitor. No dose-limiting toxicities were observed. One patient with esophageal cancer and one with gastric cancer treated with RAD001 at 10 mg/day showed marked tumor responses.

Conclusions

Treatment of Japanese cancer patients with RAD001 may be undertaken with the expectation that previously determined pharmacokinetic and safety profiles apply. The drug may hold promise for treatment of esophageal and gastric cancer.

Pancreatic cancer: molecular pathogenesis and new therapeutic targets

Patients with pancreatic cancer normally present with advanced disease that is lethal and notoriously difficult to treat. Survival has not improved dramatically despite routine use of chemotherapy and radiotherapy; this situation signifies an urgent need for novel therapeutic approaches. Over the past decade, a large number of studies have been published that aimed to target the molecular abnormalities implicated in pancreatic tumor growth, invasion, metastasis, angiogenesis and resistance to apoptosis. This research is of particular importance, as data suggest that a large number of genetic alterations affect only a few major signaling pathways and processes involved in pancreatic tumorigenesis. Although laboratory results of targeted therapies have been impressive, until now only erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has demonstrated modest survival benefit in combination with gemcitabine in a phase III clinical trial. Whilst the failures of targeted therapies in the clinical setting are discouraging, lessons have been learnt and new therapeutic targets that hold promise for the future management of the disease are continuously emerging. This Review describes some of the important developments and targeted agents for pancreatic cancer that have been tested in clinical trials.

Targeted therapies for pancreatic cancer

INTRODUCTION

Pancreatic cancer is a devastating malignancy and a leading cause of cancer mortality. Furthermore, early diagnosis represents a serious hurdle for clinicians, as symptoms are non-specific and usually manifest in advanced, treatment-resistant stages of the disease.

SOURCES OF DATA

Here, we review the rationale and progress of targeted therapies currently under investigation.

AREAS OF AGREEMENT

At present, chemoradiation regimes are administered palliatively, and produce only marginal survival benefits, underscoring a desperate need for more effective treatment modalities.

AREAS OF CONTROVERSY

Questions have been raised as to whether erlotinib, the only targeted therapy to attain a statistically significant increase in median survival, is cost-effective.

GROWING POINTS

The last decade of research has provided us with a wealth of information regarding the molecular nature of pancreatic cancer, leading to the identification of signalling pathways and their respective components which are critical for the maintenance of the malignant phenotype.

AREAS TIMELY FOR DEVELOPING RESEARCH

These proteins thus represent ideal targets for novel molecular therapies which embody an urgently needed novel treatment strategy.