Cardiorespiratory effects of immunotherapy with interleukin-2

Atrial fibrillation in cancer, anticancer therapies, and underlying mechanisms

Atrial fibrillation (AF) is a common arrhythmic complication in cancer patients and can be exacerbated by traditional cytotoxic and targeted anticancer therapies. Increased incidence of AF in cancer patients is independent of confounding factors, including preexisting myocardial arrhythmogenic substrates, type of cancer, or cancer stage. Mechanistically, AF is characterized by fast unsynchronized atrial contractions with rapid ventricular response, which impairs ventricular filling and results in various symptoms such as fatigue, chest pain, and shortness of breath. Due to increased blood stasis, a consequence of both cancer and AF, concern for stroke increases in this patient population. To compound matters, cardiotoxic anticancer therapies themselves promote AF; thereby exacerbating AF morbidity and mortality in cancer patients. In this review, we examine the relationship between AF, cancer, and cardiotoxic anticancer therapies with a focus on the shared molecular and electrophysiological mechanisms linking these disease processes. We also explore the potential role of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in the management of anticancer-therapy-induced AF.

Drug-induced atrial fibrillation. A narrative review of a forgotten adverse effect

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased morbidity and mortality. There is clinical evidence that an increasing number of cardiovascular and non-cardiovascular drugs, mainly anticancer drugs, can induce AF either in patients with or without pre-existing cardiac disorders, but drug-induced AF (DIAF) has not received the attention that it might deserve. In many cases DIAF is asymptomatic and paroxysmal and patients recover sinus rhythm spontaneously, but sometimes, DIAF persists, and it is necessary to perform a cardioversion. Furthermore, DIAF is not mentioned in clinical guidelines on the treatment of AF. The risk of DIAF increases in elderly and in patients treated with polypharmacy and with risk factors and comorbidities that commonly coexist with AF. This is the case of cancer patients. Under these circumstances ascribing causality of DIAF to a given drug often represents a clinical challenge. We review the incidence, the pathophysiological mechanisms, risk factors, clinical relevance, and treatment of DIAF. Because of the limited information presently available, further research is needed to obtain a deeper insight into DIAF. Meanwhile, it is important that clinicians are aware of the problem that DIAF represents, recognize which drugs may cause DIAF, and consider the possibility that a drug may be responsible for a new-onset AF episode.

The Heart of the Matter: Immune Checkpoint Inhibitors and Immune-Related Adverse Events on the Cardiovascular System

Cancer remains a prominent global cause of mortality, second only to cardiovascular disease. The past decades have witnessed substantial advancements in anti-cancer therapies, resulting in improved outcomes. Among these advancements, immunotherapy has emerged as a promising breakthrough, leveraging the immune system to target and eliminate cancer cells. Despite the remarkable potential of immunotherapy, concerns have arisen regarding associations with adverse cardiovascular events. This review examines the complex interplay between immunotherapy and cardiovascular toxicity and provides an overview of immunotherapy mechanisms, clinical perspectives, and potential biomarkers for adverse events, while delving into the intricate immune responses and evasion mechanisms displayed by cancer cells. The focus extends to the role of immune checkpoint inhibitors in cancer therapy, including CTLA-4, PD-1, and PD-L1 targeting antibodies. This review underscores the multifaceted challenges of managing immunotherapy-related cardiovascular toxicity. Risk factors for immune-related adverse events and major adverse cardiac events are explored, encompassing pharmacological, treatment-related, autoimmune, cardiovascular, tumor-related, social, genetic, and immune-related factors. The review also advocates for enhanced medical education and risk assessment tools to identify high-risk patients for preventive measures. Baseline cardiovascular evaluations, potential prophylactic strategies, and monitoring of emerging toxicity symptoms are discussed, along with the potential of adjunct anti-inflammatory therapies.

T cells expressing a HER2-specific chimeric antigen receptor as treatment for breast cancer

PURPOSE

Human endothelial growth factor receptor-2 (HER2) is a leucine kinase receptor that is closely related to cell growth and differentiation. It is very weakly expressed in a few epithelial cells in normal tissue. Abnormal expression of HER2 usually leads to sustained activation of downstream signaling pathways, enabling epithelial cell growth, proliferation, and differentiation; this disturbs normal physiological processes and causes tumor formation. Overexpression of HER2 is related to the occurrence and development of breast cancer. HER2 has become a well-established immunotherapy target for breast cancer. We chose to construct a second-generation CAR targeting HER 2 to test whether it kills breast cancer.

METHODS

We constructed a second-generation CAR molecule targeting HER2, and we generated cells expressing this second-generation CAR through lentivirus infection of T lymphocytes. LDH assay and flow cytometry were perform to detect the effect of cells and animal models.

RESULTS

The result indicated that the CARHER2 T cells could selectively kill cells with high Her2 expression. The PBMC-activated/CARHer2 cells had stronger in vivo tumor suppressive activity than PBMC-activated cells, and administration of PBMC-activated/CARHer2 cells significantly improved the survival of tumor-bearing mice, and induced the production of more Th1 cytokines in tumor-bearing NSG mice.

CONCLUSIONS

We prove that the generated T cells carrying the second-generation CARHer2 molecule could effectively guide immune effector cells to identify and kill HER2-positive tumor cells and inhibit tumors in model mice.

Causes of death among patients with cutaneous melanoma: a US population-based study

Research on mortality outcomes and non-cancer-related causes of death in patients with cutaneous melanoma (CM) remains limited. This study aimed to identify the prevalence of non-cancer-related deaths following CM diagnosis. The data of 224,624 patients diagnosed with malignant CM in the United States between 2000 and 2019 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. We stratified our cohort based on their melanoma stage at diagnosis and further calculated standardized mortality ratios (SMRs) for each cause of death, comparing their relative risk to that of the general US population. The total number of fatalities among melanoma patients was 60,110, representing 26.8% of the total cases. The percentage of deaths is directly proportional to the disease stage, reaching 80% in distant melanoma. The highest fatalities among the localized melanoma group (25,332; 60.5%) occurred from non-cancer causes, followed by melanoma-attributable deaths (10,817; 25.8%). Conversely, melanoma is the leading cause of death in regional and distant melanoma cohorts. Cardiovascular and cerebrovascular diseases were the most prevalent non-cancer causes of death among the three disease-stage cohorts. Compared to the general population, we did not observe an increased risk of death due to non-cancer causes in the localized CM cohort, while patients diagnosed with regional and distant CMs had a statistically significant higher risk of death from all the reported major causes of death.

Atrial fibrillation, cancer and anticancer drugs

Active cancer is associated with an increased risk of atrial fibrillation (AF), which varies depending on the pre-existing substrate (particularly in older patients), the cancer type and stage, and the anticancer therapeutics being taken. To date, studies have not been able to identify the individual contribution of each factor. During anticancer drug therapy, AF may occur with a frequency of ≈ 15-20% according to several factors, including the patient's baseline cardiovascular toxicity risk and the AF-detection strategies used. Many anticancer drugs have been associated with AF or AF reporting, both in terms of incident and recurrent AF, but robust data are lacking. Only bruton tyrosine kinase inhibitor associated AF (mainly ibrutinib) has a high level of evidence, with a ≈ 3-4-fold higher risk of AF. AF in patients with active cancer is associated with a twofold higher risk of systemic thromboembolism or stroke, and the "TBIP" (Thromboembolic risk, Bleeding risk, drug-drug Interactions, Patient preferences) structured approach must be used to evaluate the need for anticoagulation therapy. AF in patients with active cancer is also associated with a sixfold higher risk of heart failure, and optimal symptom control must be targeted, usually with rate-control drugs (beta-blockers), but a rhythm-control strategy may be proposed in patients remaining symptomatic despite optimal rate-control. AF is generally manageable, with the continuation of anticancer drugs (including ibrutinib); interruption of cancer drugs must be avoided whenever possible and weighed against the risk of cancer progression.

Atrial Fibrillation Induced by Anticancer Drugs and Underling Mechanisms

ABSTRACT

Cancer therapy has made major progress in the past several decades, but treatments are often accompanied by significant side effects. Arrhythmias are a widespread complication of some antineoplastic drugs, with atrial fibrillation (AF) being the most often encountered drug-associated arrhythmia. Preexisting AF risk factors are commonly present in cancer patients who develop drug-associated AF, and active cancer itself may cause or promote AF. Although anticancer drugs may induce AF in cancer patients without AF risk factors, it appears that most drug-associated AF develop when cancer drugs add or aggravate precancer-existing and/or cancer-related pro-AF factors/alterations, additively or synergistically producing AF. Abnormalities in intracellular calcium activity seem to be involved in the generation of anticancer drug-induced AF. In cancer survivors with cancer therapy-induced cardiomyopathy, AF often occurs, with most of the arrhythmias likely to develop secondary to the cardiomyopathy. AF may lead to modification or even cessation of cancer therapy. The management of AF in patients with cancer is currently conducted largely based on pragmatic assumptions. This review briefly discusses AF caused by anticancer drugs and the underlying mechanisms.

Acute and Chronic Cardiopulmonary Effects of High Dose Interleukin-2 Therapy: An Observational Magnetic Resonance Imaging Study

High dose interleukin-2 (IL-2) is known to be associated with cardiopulmonary toxicity. The goal of this study was to evaluate the effects of high dose IL-2 therapy on cardiopulmonary structure and function. Combined cardiopulmonary magnetic resonance imaging (MRI) was performed in 7 patients in the acute period following IL-2 therapy and repeated in 4 patients in the chronic period. Comparison was made to 10 healthy volunteers. IL-2 therapy was associated with myocardial and pulmonary capillary leak, tissue oedema and cardiomyocyte injury, which resulted in acute significant left ventricular (LV) dilatation, a reduction in LV ejection fraction (EF), an increase in LV mass and a prolongation of QT interval. The acute effects occurred irrespective of symptoms. In the chronic period many of the effects resolved, but LV hypertrophy ensued, driven by focal replacement and diffuse interstitial myocardial fibrosis and increased cardiomyocyte mass. In conclusion, IL-2 therapy is ubiquitously associated with acute cardiopulmonary inflammation, irrespective of symptoms, which leads to acute LV dilatation and dysfunction, increased LV mass and QT interval prolongation. Most of these effects are reversible but IL-2 therapy is associated with chronic LV hypertrophy, driven by interstitial myocardial fibrosis and increased cardiomyocyte mass. The findings have important implications for the monitoring and long term impact of newer immunotherapies. Future studies are needed to improve risk stratification and develop cardiopulmonary-protective strategies.

Cardiotoxicity of Systemic Melanoma Treatments

OPINION STATEMENT

Melanoma is the least common but most dangerous skin cancer, accounting for 75% of all deaths from a primary cutaneous malignancy, with incidence rates rising significantly over the last decade. Traditional treatments for melanoma including interferon and cytotoxic chemotherapy had marginal efficacy. With the advent of targeted and immunotherapies, the prognosis for patients with advanced melanoma has significantly improved including those with metastatic disease to the heart. BRAF and MEK inhibitors as well as immune checkpoint inhibitors have become front line therapy for eligible patients with metastatic melanoma and have led to long-term durable response and in some cases can be curative. Despite these oncologic advances, various treatment-limiting side effects can occur. In particular, cardiovascular toxicities can contribute to overall morbidity and mortality in these patients. Toxicities range from asymptomatic QT prolongation and mild LV dysfunction to fulminant myocarditis and potentially life-threatening arrhythmias. A multidisciplinary approach to the care of these patients which includes cardio-oncology evaluation is necessary to develop both risk mitigation and treatment strategies to ensure patients continue receiving necessary and effective melanoma treatments while minimizing long-term adverse cardiovascular effects.

Immunotherapeutic Strategies in Cancer and Atherosclerosis-Two Sides of the Same Coin

The development and clinical approval of immunotherapies has revolutionized cancer therapy. Although the role of adaptive immunity in atherogenesis is now well-established and several immunomodulatory strategies have proven beneficial in preclinical studies, anti-atherosclerotic immunotherapies available for clinical application are not available. Considering that adaptive immune responses are critically involved in both carcinogenesis and atherogenesis, immunotherapeutic approaches for the treatment of cancer and atherosclerosis may exert undesirable but also desirable side effects on the other condition, respectively. For example, the high antineoplastic efficacy of immune checkpoint inhibitors, which enhance effector immune responses against tumor cells by blocking co-inhibitory molecules, was recently shown to be constrained by substantial proatherogenic properties. In this review, we outline the specific role of immune responses in the development of cancer and atherosclerosis. Furthermore, we delineate how current cancer immunotherapies affect atherogenesis and discuss whether anti-atherosclerotic immunotherapies may similarly have an impact on carcinogenesis.

Drug-Induced Atrial Fibrillation / Atrial Flutter

Drug-induced atrial fibrillation / flutter (DIAF) is a serious and potentially life-threatening complication of pharmacotherapy. Purpose of the work: systematization and analysis of scientific literature data on drugs, the use of which can cause the development of DIAF, as well as on epidemiology, pathophysiological mechanisms, risk factors, clinical picture, diagnosis and differential diagnosis, treatment and prevention of DIAF. Analysis of the literature has shown that many groups of drugs can cause the development of DIAF, with a greater frequency while taking anticancer drugs, drugs for the treatment of the cardiovascular, bronchopulmonary and central nervous systems. The mechanisms and main risk factors for the development of DIAF have not been finally established and are known only for certain drugs, therefore, this section requires further study. The main symptoms of DIAF are due to the severity of tachycardia and their influence on the parameters of central hemodynamics. For diagnosis, it is necessary to conduct an electrocardiogram (ECG) and Holter monitoring of an ECG and echocardiography. Differential diagnosis should be made with AF, which may be caused by other causes, as well as other rhythm and conduction disturbances. Successful treatment of DIAF is based on the principle of rapid recognition and immediate discontinuation of drugs (if possible), the use of which potentially caused the development of adverse drug reactions (ADR). The choice of management strategy: heart rate control or rhythm control, as well as the method of achievement (medication or non-medication), depends on the specific clinical situation. For the prevention of DIAF, it is necessary to instruct patients about possible symptoms and recommend self-monitoring of the pulse. It is important for practitioners to be wary of the risk of DIAF due to the variety of drugs that can potentially cause this ADR.

Chemotherapy-Induced Arrhythmia - Underrecognized and Undertreated

Cancer is one of the leading causes of death worldwide. Chemotherapy-induced arrhythmia is a potential complication of treatment that confers increased morbidity and mortality. The relationship between chemotherapeutic agents and arrhythmias is poorly established. Atrial fibrillation, ventricular ectopic beats, and prolonged QTc are the most common arrhythmias suffered by cancer patients undergoing chemotherapy. The treatment of atrial fibrillation in cancer is complicated by complex drug-drug interactions and a lack of evidence guiding practice. Furthermore, the normal risk assessment scores utilized in the decision-making for anticoagulation in the normal population are not validated in the cancer population. Multiple agents are implicated in prolonging the QTc, and this can often have adverse consequences for both the patient and the treatment of their cancer. This can manifest as torsades de pointes and sudden cardiac death. It is advised that, during treatment, oncologists should have close liaison with cardio-oncologists to ensure optimum patient management.

Cardiovascular Toxicity and Mortality Associated With Adoptive Cell Therapy and Tumor-infiltrating Lymphocytes for Advanced Stage Melanoma

Adoptive cellular therapy (ACT) with tumor-infiltrating lymphocytes (TILs) has emerged as an effective treatment option for unresectable stage III/IV metastatic melanoma. Acute toxicities, particularly cardiovascular (CV), can have a significant effect on the completion of therapy. We abstracted information on 43 patients who received ACT-TIL treatment for melanoma at the Moffitt Cancer Center between 2010 and 2016. The Student t tests and χ2 tests were used to compare patient characteristics by presence versus absence of specific CV complications. In this cohort, 32.6% developed hypotension requiring treatment with intravenous fluids and pressors, 14% atrial fibrillation, and 2.3% troponin elevations suggestive of myocardial damage. No patients developed clinical heart failure, and among the patients that underwent echocardiography, there was no significant difference in mean left ventricular ejection fraction before or after therapy (62.9% vs. 63.5%, respectively, P=0.79). There was also no statistically significant difference in survival between those with and without CV complications (overall survival=61.9%, mean: 26.0 mo and progression-free survival=45.2%, mean: 18.1 mo). CV toxicities are common in ACT-TIL protocols; however, survival does not appear to be significantly affected. Further research is needed to define mechanisms and potential prevention strategies to help clinicians manage these complications and mitigate risk.

Cardiotoxic mechanisms of cancer immunotherapy - A systematic review

Cancer immunotherapy is a success story of translational medicine that has led to improved survival in patients with different difficult-to-treat types of cancer, such as metastasized melanoma, non-small cell lung cancer or renal cell carcinoma. These novel therapeutic agents exert their antitumor effects by activating the patients' immune system against cancer cells. Immunotherapy can be divided into active agents, such as anti-tumour vaccines or adoptive T-cell transfer, and passive immunotherapies like monoclonal antibodies, checkpoint inhibitors, cytokine therapy, bispecific T-cell engagers. After initial experimental use, broad clinical application revealed a number of important cardiovascular side effects of immunotherapeutics, which limit treatment options and decrease patients' prognosis and quality of life. With the rising rate of new immunotherapeutics at a hand, the number of patients receiving cancer immunotherapy will constantly increase, resulting in improved long-term survival rates. This review aims to summarize available cancer immunotherapies, their mechanism of action, currently known cardiovascular toxicities and their treatment. Further optimization of patient care will depend on the combined efforts by oncologists, cardiologists and cardiac surgeons to identify patients at risk and the implementation of interdisciplinary screening and treatment strategies. It is therefore crucial to familiarize heart specialists with novel cancer therapeutics and their potential adverse effects.

Identification of anticancer drugs associated with atrial fibrillation: analysis of the WHO pharmacovigilance database

AIMS

The explosion of novel anticancer therapies has meant emergence of cardiotoxicity signals including atrial fibrillation (AF). Reliable data concerning the liability of anticancer drugs in inducing AF are scarce. Using the World Health Organization individual case safety report database, VigiBase®, we aimed to determine the association between anticancer drugs and AF.

METHODS AND RESULTS

A disproportionality analysis evaluating the multivariable-adjusted reporting odds ratios for AF with their 99.97% confidence intervals was performed for 176 U.S. Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-labelled anticancer drugs in VigiBase®, followed by a descriptive analysis of AF cases for the anticancer drugs identified in VigiBase®. ClinicalTrial registration number: NCT03530215. A total of 11 757 AF cases associated with at least one anticancer drug were identified in VigiBase® of which 95.8% were deemed serious. Nineteen anticancer drugs were significantly associated with AF of which 14 (74%) are used in haematologic malignancies and 9 (45%) represented new AF associations not previously confirmed in literature including immunomodulating agents (lenalidomide, pomalidomide), several kinase inhibitors (nilotinib, ponatinib, midostaurin), antimetabolites (azacytidine, clofarabine), docetaxel (taxane), and obinutuzumab, an anti-CD20 monoclonal antibody.

CONCLUSION

Although cancer malignancy itself may generate AF, we identified 19 anticancer drugs significantly associated with a significant increase in AF over-reporting. This pharmacovigilance study provides evidence that anticancer drugs themselves could represent independent risk factors for AF development. Dedicated prospective clinical trials are now required to confirm these 19 associations. This list of suspected anticancer drugs should be known by physicians when confronted to AF in cancer patients, particularly in case of haematologic malignancies.

Anticancer drug-induced cardiac rhythm disorders: Current knowledge and basic underlying mechanisms

Significant advances in cancer treatment have resulted in decreased cancer related mortality for many malignancies with some cancer types now considered chronic diseases. Despite these improvements, there is increasing recognition that many cancer patients or cancer survivors can develop cardiovascular diseases, either due to the cancer itself or as a result of anticancer therapy. Much attention has focused on heart failure; however, other cardiotoxicities, notably cardiac rhythm disorders, can occur without underlying cardiomyopathy. Supraventricular tachycardias occur in cancer patients treated with cytotoxic chemotherapy (anthracyclines, gemcitabine, cisplatin and alkylating-agents) or kinase-inhibitors (KIs) such as ibrutinib. Ventricular arrhythmias, with a subset of them being torsades-de-pointes (TdP) favored by QTc prolongation have been reported: this may be the result of direct hERG-channel inhibition or a more recently-described mechanism of phosphoinositide-3-kinase inhibition. The major anticancer drugs responsible for QTc prolongation in this context are KIs, arsenic trioxide, anthracyclines, histone deacetylase inhibitors, and selective estrogen receptor modulators. Anticancer drug-induced cardiac rhythm disorders remain an underappreciated complication even by experienced clinicians. Moreover, the causal relationship of a particular anticancer drug with cardiac arrhythmia occurrence remains challenging due in part to patient comorbidities and complex treatment regimens. For example, any cancer patient may also be diagnosed with common diseases such as hypertension, diabetes or heart failure which increase an individual's arrhythmia susceptibility. Further, anticancer drugs are generally usually used in combination, increasing the challenge around establishing causation. Thus, arrhythmias appear to be an underappreciated adverse effect of anticancer agents and the incidence, significance and underlying mechanisms are now being investigated.

Prevention by L-Carnitine of Interleukin-2-Related Cardiac Toxicity during Cancer Immunotherapy

Aims and Background

Cardiac toxicity has been observed during IL-2 cancer immunotherapy. Because of its trophic action on the myocardial tissue, the use of L-carnitine has been evaluated during IL-2 therapy in advanced cancer patients with clinically important cardiac diseases.

Methods

The study included 30 cancer patients, who were randomized to treatment with IL-2 alone or IL-2 plus L-carnitine (1000 mg/day orally). IL-2 was injected subcutaneously at a daily dose of 6 million IU for 5 days/week for 4-6 weeks.

Results

The percentage of cardiac complications was significantly lower in patients concomitantly treated with L-carnitine than those receiving IL-2 alone (0/15 vs 4/15; P < 0.05), whereas no difference was seen in mean creatine phosphokinase levels on study.

Conclusions

The results would suggest that L-carnitine may be used successfully to prevent cardiac complications during IL-2 immunotherapy in cancer patients with clinically relevant cardiac disorders. Since cardiac metabolism depends mainly on fatty acid oxidation, the stimulatory role of L-carnitine on fatty acid oxidation could explain at least in part its ability to prevent heart disturbances in response to IL-2 administration.

Evaluation of the Cardiovascular Toxicity Related to Cancer Immunotherapy with Interleukin-2 by Monitoring Atrial Natriuretic Peptide Secretion: A Case Report

Increased capillary permeability and severe hypotension represent the two major cardiovascular complications of IL-2 immunotherapy. The mechanisms responsible for IL-2 cardiovascular toxicity are still obscure. Since increased vascular permeability and vasodilatation may be also induced by the cardiac hormone atrial natriuretic peptide (ANP), we have evaluated ANP concentrations in relation to mean arterial pressure in one patient with metastatic renal carcinoma, treated with a 24-h intravenous infusion of IL-2 at a dose of 3 × 106 Cetus U/m2/day for 5 days. The results showed that episodes of important hypotension were associated with abnormally high plasma levels of ANP. Owing to its vasodilator activity, exagerated ANP secretion, perhaps due to an inappropriate cardiac endocrine function in response to hemodynamic changes induced by IL-2, may play a role in hypotension, which occurs during IL-2 immunotherapy for cancer.

Activation of the Complement System during Immunotherapy of Cancer with Interleukin-2: A Possible Explanation of the Capillary Leak Syndrome

The capillary leak syndrome, responsible for fluid loss into the interstitial space, represents one of the major cardiovascular toxicities of IL-2 during the immunotherapy of cancer. The mechanisms involved in the increased vascular permeability have still to be better understood. The present study was carried out to investigate the role of the complement system in mediating the IL-2 vascular toxicity. The study was performed in metastatic renal cancer patients, treated with IL-2 through a 24-hour i.v. infusion at a daily dose of 3 × 106 U/m2 for 5 consecutive days, corresponding to one IL-2 course. Six IL-2 courses were evaluated. C3 and C4 were measured daily during IL-2 infusion, and 2 and 5 days after its interruption. IL-2 administration induced a significant decrease in both C3 and C4 mean levels, which became within the normal range 5 days after the end of IL-2 infusion. These results show that IL-2 administration may directly activate the complement system through the classical pathway, which might play a role in determining the increased vascular permeability.

Cardiovascular Toxicities Associated with Cancer Immunotherapies

PURPOSE OF REVIEW

We review the cardiovascular toxicities associated with cancer immune therapies and discuss the cardiac manifestations, potential mechanisms, and management strategies.

RECENT FINDINGS

The recent advances in cancer immune therapy with immune checkpoint inhibitors and adoptive cell transfer have improved clinical outcomes in numerous cancers. The rising use of cancer immune therapy will lead to a higher incidence in immune-related adverse events. Recent studies have highlighted several reports of severe cases of acute cardiotoxic events with immune therapy including fulminant myocarditis. We believe that immune-mediated myocarditis is a driving mechanism behind these cardiovascular toxicities and requires vigilant screening and prompt management with corticosteroids and immune-modulating drugs, especially with combination immune therapies. While the incidence of serious cardiovascular toxicities with immune therapy appears low, these can be life-threatening especially when manifesting as acute immune-mediated myocarditis. Further collaborative studies are needed to effectively identify, characterize, and manage these events.

Transplantation and Adoptive Cellular Therapy of Cancer: The Role of T-Cell Growth Factors

The ability to transfer cultured lymphocytes required the availability and the understanding of the use of the T-cell growth factors IL-2, IL-4, IL-7, and IL-12. Application of these cytokines in vitro and in vivo has allowed the modern development of adoptive transfer of tumor reactive lymphocytes to the modern immunotherapy of patients with cancer. In a randomized prospective study of IL-2 administration compared with IL-2 and lymphokine-activated killer (LAK) cells, no increase in response rate was observed. In a total of 90 patients randomized to receive LAK and IL-2 and 91 patients randomized to receive IL-2 alone, there were a total of 24 responses in patients receiving cells and IL-2 and 16 responses in those receiving IL-2 alone (no significant difference). There was some suggestion that complete responses were observed more often in melanoma patients treated with LAK and IL-2. The most interesting aspect of this study is the prolonged duration of responses, lasting for many months or years. Unfortunately, given the large numbers of variables that were examined, it became very difficult to demonstrate a clear-cut association between clinical outcome (response) and any variable that was routinely measured. Significant antitumor responses have been observed greater than expected with IL-2 alone, with the administration of tumor-infiltrating lymphocytes to patients with melanoma. We currently use hollow fiber devices (Cellco, Germantown, MD) to expand cells up through the many doublings required to generate approximately 1-2 × 1011 cells over a period of 6 wk in culture. In a recent review of the results in patients with melanoma treated on such regimens in combination with high-dose IL-2, an approximately 20-50% response rate has been observed. The factors associated with response are still unclear. Although we initially felt that it was associated with specific lysis, subsequent studies from our group suggest that the relevant factor is specific cytokine (INF-γ, GM-CSF, TNF) production upon tumor stimulation. Additional studies will need to be done to clarify these issues.

Continuous cardiac output and hemodynamic monitoring: high temporal correlation between plasma TNF-α and hemodynamic changes during a sepsis-like state in cancer immunotherapy

Through continuous cardiac output monitoring, we investigated the temporal relationship between hemodynamic changes and plasma cytokines in a cancer patient who developed collateral sepsis to immunotherapy. A 52-year-old male with metastatic renal cell carcinoma received interleukin-2 (IL-2) infusion completing 72 h of administration. The patient developed 3 sepsis-like states including systemic inflammatory response syndrome (SIRS), shock, and multiple organ dysfunction syndrome (MODS). Hemodynamic parameters including systemic vascular resistance index (SVRI), left ventricular stroke work index (LVSWI) and cardiac index (CI) were measured over 60 h. Peripheral blood was drawn when SVRI dropped 20% in the patient and plasma cytokines including TNF-α , IL-6 and IL-1β were measured using ELISA. After 60 h of immunotherapy, the patient showed a 63.4% decrease in SVRI, 54.5% decrease in LVSWI and 65.4% increase in CI. The evaluation of systemic cytokines revealed different kinetic patterns: (i) a sustained increase in TNFα levels through all 3 sepsis-like states; (ii) IL-6 increased preferentially during SIRS and shock, while up/down-responses were found during MODS; (iii) IL-1β was undetectable during the entire study period. A high temporal relationship between hemodynamic changes and plasma TNF-α, but not IL-6, was found. Although there are factors other than cytokines that can alter vascular resistance, this finding could represent an approach to evaluate the course of hemodynamia and probably the systemic cytokine expression after IL-2 administration in renal cancer.

[Comorbidity of cardiovascular diseases and cancers: Problems in the diagnosis of cardiotoxic effects of chemo- and radiation therapy]

Cardiovascular diseases (CVD) and cancers are the leaders in their prevalence and the major causes of death in economically developed countries, determining their high sociomedical significance in society. Improvement of methods for the early diagnosis and treatment of cancers has contributed to increases in relapse-free survival and life expectancy in these patients. At the same time, the new problems have emerged particularly in the development of various cardiovascular events/diseases when treating cancer, which may predict worse prognosis in patients and be an independent cause of death. To search for new markers of cardiotoxicity at early stages and to develop effective methods for the prevention and personalized treatment of cancer and CVD are the problems that can be solved only by joint efforts of cardiologists and oncologists.

Plasma angiopoietin 2 concentrations are related to impaired lung function and organ failure in a clinical cohort receiving high-dose interleukin 2 therapy

INTRODUCTION

The pathophysiology and therapeutic options in sepsis-induced lung injury remain elusive. High-dose interleukin 2 therapy (HDIL-2) is an important protocol for advanced malignancies but is limited by systemic inflammation and pulmonary edema that is indistinguishable from sepsis. In preclinical models, IL-2 stimulates angiopoietin 2 (AngP-2) secretion, which increases endothelial permeability and causes pulmonary edema. However, these relationships have not been fully elucidated in humans. Furthermore, the relevance of plasma AngP-2 to organ function is not clear. We hypothesized that plasma AngP-2 concentrations increase during HDIL-2 and are relevant to clinical pathophysiology.

METHODS

We enrolled 13 subjects with metastatic melanoma or renal cell carcinoma admitted to receive HDIL-2 and collected blood and spirometry data daily. The plasma concentrations of AngP-2 and IL-6 were measured with enzyme-linked immunosorbent assay.

RESULTS

At baseline, the mean AngP-2 concentration was 2.5 (SD, 1.0) ng/mL. Angiopoietin 2 concentrations increased during treatment: the mean concentration on the penultimate day was 16.0 (SD, 4.5) ng/mL and increased further to 18.6 (SD, 4.9) ng/mL (P < 0.05 vs. penultimate) during the last day of therapy. The forced expiratory volume in 1 s decreased during treatment. Interestingly, plasma AngP-2 concentrations correlated negatively with forced expiratory volume in 1 s (Spearman r = -0.78, P < 0.0001). Plasma AngP-2 concentrations also correlated with plasma IL-6 concentrations (r = 0.61, P < 0.0001) and Sequential Organ Failure Assessment scores (r = 0.68, P < 0.0001).

CONCLUSIONS

Plasma AngP-2 concentrations increase during HDIL-2 administration and correlate with pulmonary dysfunction. High-dose IL-2 may serve as a clinical model of sepsis and acute lung injury. Further investigation is warranted.

Serum levels of interleukin-2 predict the recurrence of atrial fibrillation after pulmonary vein ablation

AIMS

Interleukin-2 has a significant antitumor activity in some types of cancer, and has been associated with the development of atrial fibrillation (AF). In addition, IL-2 serum levels in recent onset AF have been related with pharmaceutical cardioversion outcomes. We evaluated the hypothesis that a relationship exists between inflammation and the outcome of catheter ablation of AF.

METHODS

We studied 44 patients with paroxysmal AF who underwent catheter ablation. Patients with structural heart disease, coronary artery or valve disease, active inflammatory disease, known or suspected neoplasm, endocrinopathies, or exposure to anti-inflammatory drugs were excluded. All study participants underwent evaluation with a standardized protocol, including echocardiography, and cytokine levels of interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumour necrosis factor-alpha, and gamma-interferon determination before procedure. Clinical and electrocardiographic follow-up were performed with Holter-ECG at 3, 6 and 12months in order to know if sinus rhythm was maintained.

RESULTS

After catheter ablation of the 44 patients included (53±10years, 27.3% female), all patients returned to sinus rhythm. During the first year of follow-up seven patients (15.9%) experienced recurrence of AF. The demographics, clinical and echocardiographic features, and pharmacological treatments of these patients were similar to those who maintained sinus rhythm. The only independent factor predictive of recurrence of AF was an elevated level of IL-2 (OR 1.18, 95% CI 1.12-1.38).

CONCLUSIONS

High serum levels of interleukin-2, a pro-inflammatory non-vascular cytokine, are associated with the recurrence of AF in patients undergoing catheter ablation.

Side effects of cytokines approved for therapy

Cytokines, currently known to be more than 130 in number, are small MW (<30 kDa) key signaling proteins that modulate cellular activities in immunity, infection, inflammation and malignancy. Key to understanding their function is recognition of their pleiotropism and often overlapping and functional redundancies. Classified here into 9 main families, most of the 20 approved cytokine preparations (18 different cytokines; 3 pegylated), all in recombinant human (rh) form, are grouped in the hematopoietic growth factor, interferon, platelet-derived growth factor (PDGF) and transforming growth factor β (TGFβ) families. In the hematopoietin family, approved cytokines are aldesleukin (rhIL-2), oprelvekin (rhIL-11), filgrastim and tbo-filgrastim (rhG-CSF), sargramostim (rhGM-CSF), metreleptin (rh-leptin) and the rh-erythropoietins, epoetin and darbepoietin alfa. Anakinra, a recombinant receptor antagonist for IL-1, is in the IL-1 family; recombinant interferons alfa-1, alfa-2, beta-1 and gamma-1 make up the interferon family; palifermin (rhKGF) and becaplermin (rhPDGF) are in the PDGF family; and rhBMP-2 and rhBMP-7 represent the TGFβ family. The main physicochemical features, FDA-approved indications, modes of action and side effects of these approved cytokines are presented. Underlying each adverse events profile is their pleiotropism, potency and capacity to release other cytokines producing cytokine 'cocktails'. Side effects, some serious, occur despite cytokines being endogenous proteins, and this therefore demands caution in attempts to introduce individual members into the clinic. This caution is reflected in the relatively small number of cytokines currently approved by regulatory agencies and by the fact that 14 of the FDA-approved preparations carry warnings, with 10 being black box warnings.

High dose interleukin-2 (Aldesleukin) - expert consensus on best management practices-2014

Interleukin-2 (IL-2) was historically one of the few treatments for adults with stage IV solid tumors that could produce complete responses (CRs) that were often durable for decades without further therapy. The majority of complete responders with metastatic renal cell carcinoma (mRCC) and metastatic melanoma (mM) could probably be classified as "cures". Recent publications have suggested improved efficacy, perhaps due to improved patient selection based on a better understanding of clinical features predicting outcomes. Guidelines for clinical management were established from experience at the National Cancer Institute (NCI) and an affiliation of institutions known as the Cytokine Working Group (CWG), who were among the first to utilize HD IL-2 treatment outside of the NCI. As new centers have opened, further management variations have emerged based upon center-specific experience, to optimize administration of IL-2 and provide high quality care for patients at each individual site. Twenty years of evolution in differing environments has led to a plethora of clinical experience and effective management approaches. The goal of this review is to summarize the spectrum of HD IL-2 treatment approaches, describing various effective strategies that incorporate newer adjunctive treatments for managing the side effects of IL-2 in patients with mRCC and mM. The goal for IL-2 therapy is typically to administer the maximum number of doses of IL-2 without putting the patient at unacceptable risk for severe, irreversible toxicity. This review is based upon a consensus meeting and includes guidelines on pre-treatment screening, criteria for administration and withholding doses, and defines consensus criteria for safe administration and toxicity management. The somewhat heterogeneous best practices of 2014 will be compared and contrasted with the guidelines provided in 2001 and the package inserts from 1992 and 1998.

Drug-induced atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with severe consequences, including symptoms, haemodynamic instability, increased cardiovascular mortality and stroke. While other arrhythmias such as torsades de pointes and sinus bradycardia are more typically thought of as drug induced, AF may also be precipitated by drug therapy, although ascribing causality to drug-associated AF is more difficult than with other drug-induced arrhythmias. Drug-induced AF is more likely to occur in patients with risk factors and co-morbidities that commonly co-exist with AF, such as advanced age, alcohol consumption, family history of AF, hypertension, thyroid dysfunction, sleep apnoea and heart disease. New-onset AF has been associated with cardiovascular drugs such as adenosine, dobutamine and milrinone. In addition, medications such as corticosteroids, ondansetron and antineoplastic agents such as paclitaxel, mitoxantrone and doxorubicin have been reported to induce AF. Whether bisphosphonate drugs are associated with new-onset AF remains controversial and requires further study. The potential contribution of specific drug therapy should be considered when patients present with new-onset AF.

Drug-induced atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia and an important cause of hospitalization, morbidity, and mortality. A myriad of drugs can induce AF. However, drug-induced AF (DIAF) receives little attention. Thus, this review is an attempt to attract the attention on this adverse effect.

AREAS COVERED

Published reports of drug-induced AF (DIAF) are reviewed in this paper, from January 1974 to December 2011, using the PubMed/Medline database and lateral references.

EXPERT OPINION

In most cases, DIAF is paroxysmal and terminates spontaneously, but sometimes AF persists and it is necessary to perform a cardioversion to restore sinus rhythm and avoid progression to persistent AF. Because of the short duration of DIAF, in addition to physicians/patients not being knowledgeable about this side effect, the real incidence and clinical consequences of DIAF are presently unknown. DIAF is an increasing problem, as some widely prescribed drugs can present this adverse effect. The risk is expected to increase in the elderly and in patients with comorbidities. It is important that physicians understand the significance of DIAF, to increase the collaboration between cardiac and non-cardiac professionals, and to educate patients to make them aware of this adverse side effect.

Cardio-oncology/onco-cardiology

An understanding of onco-cardiology or cardio-oncology is critical for the effective care of cancer patients. Virtually all antineoplastic agents are associated with cardiotoxicity, which can be divided into 5 categories: direct cytotoxic effects of chemotherapy and associated cardiac systolic dysfunction, cardiac ischemia, arrhythmias, pericarditis, and chemotherapy-induced repolarization abnormalities. Radiation therapy can also lead to coronary artery disease and fibrotic changes to the valves, pericardium, and myocardium. All patients being considered for chemotherapy, especially those who have prior cardiac history, should undergo detailed cardiovascular evaluation to optimize the treatment. Serial assessment of left ventricular systolic function and cardiac biomarkers might also be considered in selected patient populations. Cardiotoxic effects of chemotherapy might be decreased by the concurrent use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers. Antiplatelet or anticoagulation therapy might be considered in patients with a potential hypercoagulable state associated with chemotherapy or cancer. Open dialogue between both cardiologists and oncologists will be required for optimal patient care.

Angiopoietin 2 Is a Potential Mediator of High-Dose Interleukin 2–Induced Vascular Leak

PURPOSE

High-dose interleukin 2 (HDIL2) produces durable tumor regressions in 10% of patients with metastatic renal cell carcinoma and melanoma. However, a major toxicity is vascular leak syndrome (VLS). We previously reported elevated serum angiopoietin 2 (Ang2) in septic patients with vascular leak and hypothesized that Ang2 might also contribute to HDIL2 VLS.

EXPERIMENTAL DESIGN

Blood was collected from 14 patients receiving HDIL2 and from 4 patients receiving HDIL2 and bevacizumab, an antibody against vascular endothelial growth factor (VEGF). The effect of Ang2 was studied in vitro by incubating high Ang2 patient serum with cultured endothelial cells.

RESULTS

Pretreatment Ang2 levels were in the reference range (median, 3.3 ng/mL) and rose with each day of IL-2 therapy (median peak, 29.7 ng/mL). No trend was seen in free VEGF levels during therapy. Patients treated with HDIL2 and bevacizumab all developed VLS and elevated Ang2. High Ang2 patient sera induced propermeability structural changes in endothelial cells, an effect reversed by blockade with the competitive ligand angiopoietin 1 (Ang1).

CONCLUSIONS

Ang2 may be a mediator of HDIL2 VLS as evidenced by (a) an increase in Ang2 in all patients on HDIL2; (b) the effect of high Ang2 patient serum on cultured endothelial cells; (c) rescue of those structural changes by Ang1. The lack of correlation between VLS and serum VEGF levels in patients treated with HDIL2 alone or in combination with bevacizumab suggests that VEGF is not a major contributor to VLS or Ang2 release. These data suggest that the inhibition of Ang2 may mitigate VLS in patients receiving HDIL2.

Cardiac and cardiovascular toxicity of nonanthracycline anticancer drugs

Anthracyclines are a well-known cause of cardiotoxicity, but a number of other drugs used to treat cancer can also result in cardiac and cardiovascular adverse effects. Cardiotoxicity can result in the alteration of cardiac rhythm, changes in blood pressure and ischemia, and can also alter the ability of the heart to contract and/or relax. The clinical spectrum of these toxicities can range from subclinical abnormalities to catastrophic life-threatening, and sometimes fatal, sequelae. These events may occur acutely or may only become apparent months or years following completion of oncological treatment. Ischemia and rhythm abnormalities are treated symptomatically in most cases. Knowledge of these toxicities can aid clinicians to choose the optimal and least toxic regimen suitable for an individual patient.

ReGel® Polymer-based Delivery of Interleukin-2 as a Cancer Treatment

ReGel is an aqueous, filter sterilizable ABA tri-block polymer consisting of poly-(lactide-co-glycolide) and polyethylene glycol. We tested the suitability of this polymer to provide sustained interleukin-2 (IL-2) delivery for cancer immunotherapy. ReGel/IL-2 is liquid at or below room temperature, and is easily injectable through narrow gauge needles, but undergoes a reversible thermal transition into a bioerodible depot at body temperature. We demonstrated that ReGel/IL-2 releases IL-2 over 72 to 96 hours in vitro, without loss of bioactivity. Pharmacokinetic studies after peritumoral injection of 0.1 mL ReGel/IL-2 in mice demonstrated an early burst of IL-2 release, followed by more sustained release kinetics over 96 hours (T(1/2)beta 48 h). Less than 1.5% of the injected dose was detectable in blood or kidneys during the first 48 hours. A single peritumoral dose of ReGel/IL-2 [1 to 4 million international units (MIU) ReGel/IL-2, split into 4 quadrant injections] was administered to mice bearing subcutaneous RD-995 spindle cell carcinoma. Only the highest dose of ReGel/IL-2 tested (4.0 MIU) resulted in significant hypotension on day 3 after injection. Weekly treatment of Meth A fibrosarcoma and RENCA renal carcinoma with ReGel/IL-2 (2 MIU/dose) induced a significant reduction in tumor growth and improved survival. Reduction in tumor growth at implants remote from treated lesions was also observed, suggesting systemic activation of antitumor immunity. These findings establish that peritumoral injection of ReGel/IL-2 is an effective delivery system for cancer immunotherapy, while decreasing IL-2 toxicity. This polymer delivery system is likely to be broadly applicable for sustained delivery of other cytokines and peptides.

Inflammatory protein profile during systemic high dose interleukin-2 administration

Systemic interleukin-2 (IL-2) administration induces an assortment of downstream effects whose biological and therapeutic significance remains unexplored mostly because of the methodological inability to globally address their complexity. Protein array analysis of sera from patients with renal cell carcinoma obtained prior and during high-dose IL-2 therapy had previously revealed extensive alterations in expression of the soluble factors analyzed, whose discovery was limited by the number of capture antibodies selected for protein detection. Here, we expanded the analysis to SELDI-TOF-MS and quantitative protein analysis (nephelometry). All cytokines/chemokines detected by protein arrays were below the SELDI detection limit, while novel IL-2-specific changes in expression of acute-phase reactants and high-density lipoprotein metabolites could be identified. Serum amyloid protein A (SAA) and C-reactive protein expression were consistently up-regulated after four doses of IL-2, while other proteins were down-regulated. These findings were confirmed by SELDI immunoaffinity capture and nephelometry. Immunoaffinity capture revealed different, otherwise undetectable, isoforms of SAA. A linear correlation between peak area by SELDI and protein concentration by nephelometry was observed. Overall distinct yet complementary information was obtained using different platforms, which may better illustrate complex phenomena such as the systemic response to biological response modifiers.

Cardiotoxicity of cancer therapy

Because cancer is a leading cause of mortality in the United States, the number of therapeutic modalities available for the treatment of neoplastic processes has increased. This has resulted in a large number of patients being exposed to a wide variety of cancer therapy. Historically, it has been well recognized that antineoplastic agents may have adverse effects on multiple organs and normal tissues. The most commonly associated toxicities occur in tissues composed of rapidly dividing cells and may spontaneously reverse with minimal long-term toxicity. However, the myocardium consists of cells that have limited regenerative capability, which may render the heart susceptible to permanent or transient adverse effects from chemotherapeutic agents. Such toxicity encompasses a heterogeneous group of disorders, ranging from relatively benign arrhythmias to potentially lethal conditions such as myocardial ischemia/infarction and cardiomyopathy. In some instances, the pathogenesis of these toxic effects has been elucidated, whereas in others the precise etiology remains unknown. We review herein the various syndromes of cardiac toxicity that are reported to be associated with antineoplastic agents and discuss their putative mechanisms and treatment.

Metastatic renal cell carcinoma: CT-guided immunotherapy as a technically feasible and safe approach to delivery of gene therapy for treatment

PURPOSE

To assess the technical feasibility and safety of weekly outpatient percutaneous computed tomographic (CT)-guided intratumoral injections of interleukin-2 (IL-2) plasmid DNA in a wide variety of superficial and deep tumor sites.

MATERIALS AND METHODS

Twenty-nine patients with metastatic renal cell carcinoma and a total of 30 lesions measuring 1.0 cm(2) or greater in accessible thoracic (n = 15) or abdominal (n = 15) locations underwent up to three cycles of six weekly intratumoral IL-2 plasmid DNA injections. CT was used to guide needle placement and injection. After injection cycle 1, patients whose tumors demonstrated stable (< or =25% increase and < or =50% decrease in product of lesion diameters) or decreased size (>50% decrease in product of lesion diameters) advanced to injection cycle 2. Patients whose lesions decreased in size by more than 50% over the course of injection cycle 2 were eligible to begin injection cycle 3. An acceptable safety and technical feasibility profile for this technique was deemed to be (a) a safety and feasibility profile similar to that of single-needle biopsy and (b) an absence of serious adverse events (as defined in Title 21 of the Code of Federal Regulations) and/or unacceptable toxicities (as graded according to the National Cancer Institute Common Toxicity Criteria).

RESULTS

A total of 284 intratumoral injections were performed, with a mean of 9.8 injections (range, 6-18 injections) received by each patient. Technical success (needle placement and injection of gene therapy agent) was achieved in all cases. Complications were experienced after 42 (14.8%) of the 284 injections. The most common complication was pneumothorax (at 32 [28.6%] of 112 intrathoracic injections), for which only one patient required catheter drainage. Complications occurred randomly throughout injection cycles and did not appear to increase as patients received more injections (P =.532). No patient experienced serious adverse events or unacceptable toxicities.

CONCLUSION

Percutaneous CT-guided intratumoral immunotherapy injections are technically feasible and can be safely performed.

A nonpeptidyl mimic of superoxide dismutase, M40403, inhibits dose-limiting hypotension associated with interleukin-2 and increases its antitumor effects

Interleukin-2 (IL-2) is used to treat metastatic renal cell carcinoma and malignant melanoma, but its use is limited by the severe hypotension it produces. We have shown here that M40403, a superoxide dismutase (SOD) mimetic, blocked IL-2-induced hypotension and allowed the dose of IL-2 to be increased in mice. The reversal of IL-2-mediated hypotension was associated with an increase in plasma catecholamines. In addition, M40403 increased lymphokine-activated killer (LAK) cell cytotoxicity in vitro and in vivo, through inhibition of macrophage superoxide production. Treatment of methylcholanthrene-induced (Meth A) ascites tumors with IL-2 and > or =3 mg per kg body weight M40403 induced 50% complete remissions lasting for more than 200 d, which was longer than those of untreated mice (15-d median survival) or mice treated with IL-2 alone (22-d median). Growth of subcutaneous implants of RENCA renal carcinoma was also inhibited by the combination of IL-2 and M40403. These results established that M40403 prevented IL-2 from causing dose-limiting hypotension, while enhancing its anticancer activity.

Identification of a protein fragment of interleukin 2 responsible for vasopermeability

BACKGROUND

The cytokine interleukin 2 (IL-2) is involved in the activation of T cells and has been shown to play a central role in cancer immunotherapy. The full therapeutic potential of IL-2, however, has not been realized because of its dose-limiting systemic toxicity. We sought to identify a region of IL-2 that is responsible for the induction of vasopermeability (leaky tumor endothelium), a property associated with the toxicity of the molecule.

METHODS

Intact IL-2 or overlapping synthetic peptides of IL-2 that were chemically conjugated to tumor-targeting monoclonal antibodies (TNT-1 or Lym-1) were injected into groups of mice (n = 4) that had previously been xenotransplanted with human tumor cells (ME-180 cervical carcinoma and Raji lymphoma). Two hours later, mice received intravenous injections of radiolabeled tracer antibody, and 3 days later they were subjected to biodistribution analysis to measure the ability of each immunoconjugate to enhance tumor uptake of the tracer antibody (i.e., vasopermeability activity). The cytokine activity of the immunoconjugates was determined by assaying their ability to promote the proliferation of a mouse IL-2-dependent cell line.

RESULTS

Pretreatment of mice with an antibody/IL-2 immunoconjugate resulted in an approximately fourfold increase in radiolabeled tracer antibody uptake in the xenograft tumor as compared with uptake in mice injected with antibody alone. One synthetic fragment consisting of amino acids 22-58 contained 100% of the vasopermeability activity of IL-2 and was designated permeability-enhancing peptide (PEP). PEP had vasopermeability activity only when conjugated to a tumor-targeting antibody, had maximal activity as a dimer, and was devoid of cytokine activity.

CONCLUSIONS

The identification of PEP should aid in the discovery of ways to decrease the toxicity of IL-2. Moreover, PEP is a promising candidate for the generation of agents that can enhance the delivery of antibodies and drugs to tumors.

Kidney cancer: the Cytokine Working Group experience (1986-2001): part II. Management of IL-2 toxicity and studies with other cytokines

The Cytokine Working Group (CWG) was initially established in 1986 as the Extramural IL-2/LAK Working Group. With funding from the National Cancer Institute (NCI), the CWG was mandated to confirming data regarding the efficacy of the high-dose interleukin-2 (IL2)/lymphokine-activated killer cell (LAK cell) regimen piloted at the NCI in the treatment of renal cell cancer. Since those initial studies, the CWG has conducted a series of clinical trials, often with correlative immunologic investigations, to evaluate combination immunotherapy in attempts to enhance the efficacy of IL-2 or to reduce toxicity. Subsequently, the CWG conducted trials to demonstrate the activity of lower-dose outpatient combination cytokine regimens to help determine their role in the armamentarium of treatment for metastatic renal cell cancer. This has culminated in a phase III randomized trial comparing the activity of high-dose IL-2 with the activity of outpatient IL-2 plus interferon-alpha. The CWG also has honed the management of both high-dose IL-2 and outpatient IL-2 regimens to make these safer in the hands of experienced clinicians. In addition, the CWG has produced a series of carefully conducted clinical trials of new cytokines, again attempting to define their clinical efficacy as anticancer agents. These include studies of IL-4, IL-6, and IL-12. Currently, the CWG is conducting studies with new approaches to IL-2 therapy, as well as planning trials with new agents for treatment of renal cell cancer. This review describes these efforts conducted over the past 15 yr.