Interleukin-2 induces profound reversible cholestasis: a detailed analysis in treated cancer patients

IL-2-mediated hepatotoxicity: knowledge gap identification based on the irAOP concept

Drug-induced hepatotoxicity constitutes a major reason for non-approval and post-marketing withdrawal of pharmaceuticals. In many cases, preclinical models lack predictive capacity for hepatic damage in humans. A vital concern is the integration of immune system effects in preclinical safety assessment. The immune-related Adverse Outcome Pathway (irAOP) approach, which is applied within the Immune Safety Avatar (imSAVAR) consortium, presents a novel method to understand and predict immune-mediated adverse events elicited by pharmaceuticals and thus targets this issue. It aims to dissect the molecular mechanisms involved and identify key players in drug-induced side effects. As irAOPs are still in their infancy, there is a need for a model irAOP to validate the suitability of this tool. For this purpose, we developed a hepatotoxicity-based model irAOP for recombinant human IL-2 (aldesleukin). Besides producing durable therapeutic responses against renal cell carcinoma and metastatic melanoma, the boosted immune activation upon IL-2 treatment elicits liver damage. The availability of extensive data regarding IL-2 allows both the generation of a comprehensive putative irAOP and to validate the predictability of the irAOP with clinical data. Moreover, IL-2, as one of the first cancer immunotherapeutics on the market, is a blueprint for various biological and novel treatment regimens that are under investigation today. This review provides a guideline for further irAOP-directed research in immune-mediated hepatotoxicity.

Immuno-inflammatory in vitro hepatotoxicity models to assess side effects of biologicals exemplified by aldesleukin

Introduction

Hepatotoxicity induced by immunotherapeutics is an appearing cause for immune-mediated drug-induced liver injury. Such immuno-toxic mechanisms are difficult to assess using current preclinical models and the incidence is too low to detect in clinical trials. As hepatotoxicity is a frequent reason for post-authorisation drug withdrawal, there is an urgent need for immuno-inflammatory in vitro models to assess the hepatotoxic potential of immuno-modulatory drug candidates. We developed several immuno-inflammatory hepatotoxicity test systems based on recombinant human interleukin-2 (aldesleukin).

Methods

Co-culture models of primary human CD8+ T cells or NK cells with the hepatocyte cell line HepaRG were established and validated with primary human hepatocytes (PHHs). Subsequently, the HepaRG model was refined by increasing complexity by inclusion of monocyte-derived macrophages (MdMs). The main readouts were cytotoxicity, inflammatory mediator release, surface marker expression and specific hepatocyte functions.

Results

We identified CD8+ T cells as possible mediators of aldesleukin-mediated hepatotoxicity, with MdMs being implicated in increased aldesleukin-induced inflammatory effects. In co-cultures of CD8+ T cells with MdMs and HepaRG cells, cytotoxicity was induced at intermediate/high aldesleukin concentrations and perforin was upregulated. A pro-inflammatory milieu was created measured by interleukin-6 (IL-6), c-reactive protein (CRP), interferon gamma (IFN-γ), and monocyte chemoattractant protein-1 (MCP-1) increase. NK cells responded to aldesleukin, however, only minor aldesleukin-induced cytotoxic effects were measured in co-cultures. Results obtained with HepaRG cells and with PHHs were comparable, especially regarding cytotoxicity, but high inter-donor variations limited meaningfulness of the PHH model.

Discussion

The in vitro test systems developed contribute to the understanding of potential key mechanisms in aldesleukin-mediated hepatotoxicity. In addition, they may aid assessment of immune-mediated hepatotoxicity during the development of novel immunotherapeutics.

Interleukin-2, Ipilimumab, and Anti-PD-1: clinical management and the evolving role of immunotherapy for the treatment of patients with metastatic melanoma

Treatment of metastatic melanoma has changed dramatically in the past 5 years with the approval of six new agents (vemurafenib, dabrafenib, trametinib, ipilimumab, pembrolizumab, and nivolumab) by the US Food and Drug Administration (FDA). This review will compare the immunotherapies recently approved by the FDA (ipilimumab, nivolumab and pembrolizumab) with the long-approved immunotherapy, interleukin-2. Additional consideration will be given to the evolving landscape, including the opportunities for combination regimens. Immunotherapies have distinct mechanisms of action and unique response kinetics that differ from conventional cytotoxic and targeted therapies, and have a range of adverse events that can be safely managed by experienced health-care providers. Data suggest immunotherapies can result in long-term survival in a proportion of patients. This dynamic and evolving field of immunotherapy for melanoma will continue to offer challenges in terms of optimal patient management for the foreseeable future.

Adverse Events in Cancer Immunotherapy

Cancer immunotherapy has resulted in durable responses in patients with metastatic disease, unseen with traditional chemotherapy. Several therapies have been approved by the Food and Drug Administration for the treatment of various cancers, including: immune checkpoint inhibitors, cytokines - interleukin 2 (IL-2) and interferon alpha (IFN), and the cancer vaccine sipuleucel-T. These therapies upregulate the immune system to enhance antitumor responses. As a consequence, they can cause inflammatory and immune-related adverse events that can affect one or more organs, can be serious, and on occasion lifethreatening. The management of these adverse events is complex, and requires a multidisciplinary approach involving not only oncologists, but also other internal medicine specialists, to ensure prompt diagnosis and optimal management of these complications.

Hepatotoxicity Secondary to Chemotherapy

The difficult problem faced by multiple generation of practicing physicians is determining the cause of abnormal liver function tests in cancer patients on chemotherapy. Hepatotoxicity from chemotherapy occurs frequently from an unpredictable or idiosyncratic reaction. Despite remarkable advances in our understanding of the mechanisms of action, pharmacodynamics, and interrelationships between the liver and chemotherapy, the underlying etiology of hepatic toxicity for various agents remains unexplained. Here, we present a concise review of the broad differential diagnosis for abnormal liver function tests (LFTs) in oncology patients.

Chemotherapy-induced hepatotoxicity

Most hepatotoxicity secondary to chemotherapy is idiosyncratic and, therefore, neither dose dependent nor predictable. Some chemotherapy is cleared by the liver and requires dose adjustment in the face of significant liver dysfunction. In addition, preexisting abnormal liver function has been shown to increase the risk of hepatotoxicity. In addition to typical hepatocellular injury, other presentations, including cholestasis and hepatic sinusoidal obstruction syndrome, also commonly occur. The outcomes can range from asymptomatic liver function test abnormalities, which resolve spontaneously, to cirrhosis, which occurs despite discontinuation of the chemotherapeutic agent.

Nuclear receptors: mediators and modifiers of inflammation-induced cholestasis

Inflammation-induced cholestasis (IIC) is a frequently occurring phenomenon. A central role in its pathogenesis is played by nuclear receptors (NRs). These ligand-activated transcription factors not only regulate basal expression of hepatobiliary transport systems, but also mediate adaptive responses to inflammation and possess anti-inflammatory characteristics. The latter two functions may be exploited in the search for new treatments for IIC as well as for cholestasis in general. Current knowledge of the pathogenesis of IIC and the dual role NRs in this process are reviewed. Special interest is given to the use of NRs as potential targets for intervention.

Hepatotoxicity of Chemotherapy

The selection of an antineoplastic regimen for an oncology patient is based first on the availability of effective drugs and then on a balancing of potential treatment-related toxicities with the patient's clinical condition and associated comorbidities. Liver function abnormalities are commonly observed in this patient population and identifying their etiology is often difficult. Immunosuppression, paraneoplastic phenomena, infectious diseases, metastases, and poly-pharmacy may cloud the picture. While criteria for standardizing liver injury have been established, dose modifications often rely on empiric clinical judgment. Therefore, a comprehensive understanding of hepatotoxic manifestations for the most common chemotherapeutic agents is essential. We herein review the hepatotoxicity of commonly used antineoplastic agents and regimens.

Proposal for a histological scoring and grading system for non-alcoholic fatty liver disease

AIM/BACKGROUND

The spectrum of histopathological features in non-alcoholic fatty liver disease (NAFLD) has been well described. At least two scoring systems have been established. We propose here a system in which numerical scores are obtained using the different features.

METHODS

Twenty-five cases of well-defined NAFLD were identified. Two pathologists blinded to identifiers and clinical data independently scored the liver biopsies twice for portal fibrosis (PF: 0-6), lobular inflammation and necrosis (LIN: 0-3), Mallory bodies (MB: 0-3), hepatocyte ballooning (HB: 0-3), perisinusoidal fibrosis (PSF: 0-3) and fatty change (FC: 1-4). The kappa statistic tested observer concordance. Non-parametric measures of correlation and hierarchical cluster analysis were used to elaborate a grading system.

RESULTS

A broad spectrum of NAFLD was observed. Intra- and interobserver concordance was satisfactory. An activity score was created (AS: 0-12) as the sum of LIN, MB, HB and PSF, but not FC. A system for severity of NAFLD was developed: Grade 1 (PF: 0-2 and AS: 0-4), Grade 2 (PF: 3 or AS: 5-7) and Grade 3 (PF: 4-6 or AS: 8-12). Diabetes, elevated alkaline phosphatase and decreased platelets were associated with advanced grade.

CONCLUSIONS

This simple, reproducible NAFLD score produces a three-tier severity grade. This numerical system may prove useful in assessing disease severity and interval changes.

Intrahepatic cholestasis as a paraneoplastic syndrome associated with pheochromocytoma

Pheochromocytoma is a rare tumor of chromaffin cells that secrete catecholamines and several cytokines. The clinical manifestations are protean and may include hypertension, weight loss, sweating, palpitation, headache, anxiety, tremor, nausea, vomiting, and hypercalcemia. The tumor can mimic many unrelated diseases, leading to significant delay and difficulty in diagnosis. We report a case of a 37-yr-old male admitted with jaundice, dark urine, fever, and signs of a systemic inflammatory response. Abdominal computed tomography revealed a heterogeneously enhancing tumor between the pancreatic tail and left kidney. There was no evidence of obstruction to bile flow, neoplastic involvement of the liver or bile ducts, or infectious etiology. The tumor was removed and found to be a pheochromocytoma. Immunohistochemical analysis revealed the presence of interleukin-1beta in the tumor cells. After surgery, the jaundice resolved without further treatment, leading us to the conclusion that it was a paraneoplastic phenomenon possibly related to interleukin-1beta production. We suggest that occult pheochromocytoma should be added to the differential diagnosis of unexplained intrahepatic cholestasis.

Anaesthetic implications of anticancer chemotherapy

In anaesthetic practice we deal with cancer patients who are scheduled for operations on tumours or other manifestations of malignant disease. Those patients are often debilitated and have significant weight loss accompanied with hypoproteinaemia, anaemia and coagulation disorders. Oncological patients usually present to the anaesthetist before tumour disease surgery, but they are also candidates for elective operations (e.g. hernia repair) and urgent/emergency surgery (e.g. trauma, fractures and ileus). Chemotherapeutic agents given to these patients are potentially noxious, can affect the conduct of anaesthesia and, furthermore, may aggravate the patient's condition. In this review the most commonly used cytostatic drug regimens and their common side-effects are listed. Some preclinical studies on anaesthetic and cytostatic drug metabolism and interactions are emphasized, as well as clinically relevant perioperative alterations that may affect anaesthetic management in cancer patients. An anaesthetist may have to modify a routine anaesthetic regimen in cancer patients especially if anticancer chemotherapeutics were given. Clinically silent toxic drug effects may become apparent during operation, trauma or in the early postoperative course in such patients. Altered reactions to commonly used anaesthetics in patients receiving chemotherapeutics and an impaired stress reaction may occur in such patients. Special attention must be drawn to protection against opportunistic infections.

Effects of interleukin 2 therapy on lymphocyte magnesium levels

Interleukin 2 (IL-2) can cause partial or complete tumor regression in approximately 20% of patients with renal cell carcinoma. Among the many physiologic effects of IL-2, decreased serum levels of the divalent cations magnesium (Mg) and calcium have been demonstrated, with corresponding decreases in their urinary excretion. We investigated the effect of IL-2 on lymphocyte Mg levels among patients receiving three different dosing regimens. Twenty-eight patients with metastatic renal cell carcinoma were treated with high-dose intravenous, low-dose intravenous, or subcutaneous IL-2 therapy. Serum ionized Mg, urinary Mg, and peripheral blood mononuclear cell Mg levels were measured in samples from patients during treatment and compared with pretreatment levels. Serum Mg and ionized Mg levels decreased for all patients within 12 hours of treatment (P <.005) and remained low for the duration of therapy. Urinary Mg decreased in parallel with serum levels in all patients (P <.005). The peripheral blood mononuclear cell Mg content per cell increased within 24 hours of treatment (P <.005). The magnitude of these changes was similar during the first week of treatment for patients receiving intravenous or subcutaneous administration of IL-2. During IL-2 therapy, lymphocyte Mg increases coincident with serum Mg depletion. Mg availability may have functional implications for lymphocyte proliferation and integrin function.

Hepatotoxicity of chemotherapy

After assessment of tumor histology, the next important factor to consider in the selection of a chemotherapy regime is organ function. Patients who are to receive chemotherapy require careful assessment of liver function prior to treatment to determine which drugs may not be appropriate, and which drug doses should be modified. Following therapy abnormalities of liver function tests may be due to the therapy rather than to progressive disease, and this distinction is of critical importance. Furthermore, not all abnormalities in liver function are due to the tumor or its treatment, and other processes, such as hepatitis, must be kept in mind. This article reviews the hepatic toxicity of chemotherapeutic agents, and suggests dose modifications based upon liver function abnormalities. Emphasis is placed on agents known to be hepatotoxic, and those agents with hepatic metabolism.

Guidelines for the safe administration of high-dose interleukin-2

High-dose interleukin-2 (IL-2) results in objective clinical regression of metastatic cancer in 15% to 17% of patients with melanoma and renal cell carcinoma. Durable complete regression of all metastases is seen in 6% to 8% of patients. Based on these findings, the U.S. Food and Drug Administration has approved the use of high-dose IL-2 for the treatment of patients with metastatic melanoma and renal cell carcinoma. Interleukin-2 administration is associated with many different side effects, and after many years of use, clinicians have learned how to safely administer high-dose IL-2. This article details practical guidelines for the safe administration of high-dose IL-2.

Inflammation-induced cholestasis

Inflammatory cytokines produced in response to various infectious and non-infectious stimuli are potent inducers of intrahepatic cholestasis (inflammation-induced cholestasis). The cholestatic effect of cytokines results mainly from inhibition of expression and function of hepatocellular transport systems which normally mediate hepatic uptake and biliary excretion of bile salts and various non-bile salt organic anions (e.g. bilirubin). These cytokine effects are reversible and bile secretory function is restored upon disappearance of the inflammatory injury. This review summarizes the clinical, pathophysiological and molecular aspects of inflammation-induced cholestasis.

Drug- and chemical-induced cholestasis

Cholestasis resulting from drugs is an increasingly recognized cause of liver disease. It produces a broad clinical-pathologic spectrum of injury that includes simple jaundice, cholestatic hepatitis, and bile duct injury that can mimic extrahepatic biliary obstruction, primary biliary cirrhosis, and sclerosing cholangitis. Although the risk of drug-induced cholestasis leading to a fatal outcome is quite rare, knowledge and recognition of the various forms of cholestatic injury assumes an importance whenever clinicians are confronted with jaundice or other manifestations of liver disease in patients receiving medicinal or chemical agents.

Natural history and therapy of metastatic renal cell carcinoma: the role of interleukin-2

BACKGROUND

Despite significant advances in understanding the biology of renal cell carcinoma (RCC) during the past decade, metastatic disease remains nearly incurable and a major medical challenge. Because RCC is known to be immunogenic, immunotherapeutic agents such as recombinant human interleukin-2 (rIL-2) and interferon-alpha (IFN-alpha) have represented encouraging treatment modalities.

METHODS

A review of the natural history of and therapeutic approaches to RCC was examined. Studies involving rIL-2 alone and in combination with other adjuvant therapies were critically evaluated.

RESULTS

Overall response rates for metastatic RCC patients treated with rIL-2 were similar (i.e., in the range of 15-20%), regardless of whether rIL-2 was administered as monotherapy or in combination with IFN-alpha. Recombinant IL-2 monotherapy response rates were similar to those of IFN-alpha, but with an increased frequency of complete responses and enhanced response duration. Subcutaneous administration generally resulted in lower toxicity than intravenous administration. The roles of chemotherapy or adoptive immunotherapy in combination with rIL-2 and IFN-alpha therapy remain unclear and require further study. The importance of patient performance status as a predictor of response and survival in rIL-2 therapy was demonstrated.

CONCLUSIONS

The use of rIL-2 with or without IFN-alpha may represent the most useful therapeutic approach currently available for patients with good performance status. In patients with borderline performance status or severe comorbid disease, therapeutic approaches depend on patient factors and outcome expectation and may involve cytokine therapy. However, regardless of performance status, palliative measures and/or observation are important choices, because the majority of patients with metastatic RCC are incurable.

Acute dyslipoproteinemia induced by interleukin-2: lecithin:cholesteryl acyltransferase, lipoprotein lipase, and hepatic lipase deficiencies

Recombinant human interleukin-2 (rIL-2) is used to treat refractory cancers. During such treatment, patients develop severe hypocholesterolemia along with striking alterations in the concentration and composition of the circulating lipoproteins. The present study was undertaken to gather information about the pathogenesis of these abnormalities. Patients were studied before-, during- and after a 5-day course of high dose i.v. rIL-2. Whole plasma cholesterol was markedly reduced by rIL-2 administration (52%; P < 0.001), whereas the triglyceride concentration did not change. Thus, the lipoproteins became triglyceride enriched (P = 0.004). Low density lipoprotein cholesterol, apolipoprotein B (apoB), high density lipoprotein cholesterol, and apoA-I concentrations all decreased. Esterified cholesterol levels were markedly reduced. Total plasma apoE increased markedly, and two kinds of abnormal particles appeared: 1) beta-migrating, very low density lipoproteins; and 2) discoidal, apoE- and phospholipid-containing particles with abnormal density and electrophoretic mobility. The activities of two lipoprotein triglyceride hydrolases, lipoprotein lipase and hepatic lipase, fell significantly during treatment and returned promptly to pretreatment levels after rIL-2 was discontinued. Lecithin:cholesteryl acyltransferase (LCAT) activity also decreased significantly (64%) during treatment, but in contrast to the lipases, remained low for at least 5 days after the last dose of rIL-2 (P < 0.001). High dose i.v. rIL-2 induces severe dyslipidemia with deficiencies of both postheparin lipases and acute LCAT deficiency. Most, if not all, of the lipoprotein changes observed are explained by the LCAT deficiency that follows IL-2-induced hepatocellular injury and cholestasis.

The role of cytokines in the pathophysiology of chronic liver diseases

Many of the biological activities of cytokines are similar to clinical manifestations and abnormalities of laboratory parameters observed in chronic liver diseases (CLD). Evidence of impaired cytokine synthesis in CLD comes from studies of serum or plasma levels, supernatants of peripheral blood mononuclear cells stimulated with various agents and from studying cytokine expression locally in the liver. Circulating levels of several cytokine-regulated molecules such as neopterin, soluble IL-2 receptor, adhesion molecules, and metabolites of the nitric oxide pathway are elevated in patients with CLD. Thus inhibition of cytokine synthesis or modulation of their activity could provide not only important information about their pathophysiologic relevance but also have a profound impact on disease progression in CLD. These studies will also show whether prolonged anti-cytokine treatment with interleukin-1- or tumor necrosis factor-inhibitors interferes with host defense mechanism.

Renal, metabolic, and hemodynamic side-effects of interleukin-2 and/or interferon alpha: evidence of a risk/benefit advantage of subcutaneous therapy

Systemic immunotherapy with recombinant interleukin-2 (rIL-2) via intravenous (i.v.) and subcutaneous (s.c.) administration produces objective responses in a proportion of advanced cancer patients. While most of the previous investigations chose the i.v. route for cytokine application, there is an increasing number of trials employing s.c. rIL-2 therapy. The comparison of reported response rates for i.v. versus s.c. therapy reveals no significant differences between these modalities. In an effort to describe systemic toxicities of s.c. cytokine therapy with regard to renal, metabolic, and hemodynamic abnormalities and to compare these effects to toxicities reported upon i.v. therapy, we retrospectively evaluated 148 treatment cycles of s.c. immunotherapy given to 107 outpatients. Our study cohorts consisted of 15 patients who received s.c. rIL-2 at doses of (4.8-14.4) x 10(6) IU m-2 day-1 5 days/week for a total of 8 weeks, 20 patients who received rIFN alpha 2b at (3.0-6.0) x 10(6) m-2 day-1 thrice weekly for a total of 6 weeks, and 72 patients who were given s.c. rILFN alpha 2b at 6.0 x 10(6) U/m2, three times per week, plus s.c. rIL-2 at (14.4-18.0) x 10(6) IU/m2 on days 1 and 2, followed by 4.8 x 10(6) IU m-2 day-1 5 days/week for 6 consecutive weeks. These treatment regimens were well tolerated in the outpatient setting; no toxic death occurred, and none of the patients developed life-threatening toxicity due to a capillary leak syndrome. Upon s.c. combination therapy, dyspnea at rest occurred in 6% of patients and grade III and IV hypotension occurred in 7% and 4%, respectively; plasma protein was significantly decreased (mean nadir +/- standard deviation, 67 +/- 5 g/l). In addition, s.c. therapy led to a significant increase in serum creatinine (mean peak +/- standard deviation, 115.1 +/- 21.4 mumol/l) and urea nitrogen (mean peak +/- standard deviation, 6.5 +/- 2.5 mmol/l); electrolyte disturbances and direct nephrotoxicity never caused major clinical symptoms. This was in marked contrast to a multitude of dose-limiting and life-threatening adverse reactions reported upon i.v. rIL-2 therapy. We conclude that palliative low to intermediate-dose s.c. rIL-2/rIFN alpha combination therapy, in contrast to i.v. treatment, can be administered in the ambulatory setting with good practicability and excellent safety. This outpatient regimen is as effective against metastatic renal cell cancer as the most aggressive i.v. rIL-2 protocol reported.

Pilot study of natural human interleukin-2 in patients with chronic hepatitis B. Immunomodulatory and antiviral effects

Ten patients with chronic hepatitis B received increasing doses of nIL-2 (30,000 U, 100,000 U, 300,000 U, 1.0 million U) subcutaneously in a phase I trial. Each dose was applied once per week over 3 weeks. Serum samples were taken before and 2, 12, 24, 48 and 72 h after the first application of each dose level. Serum concentrations of interleukin-1 (IL-1), IL-2, IL-6, interferon-alfa (IFN-alpha), IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and GM-CSF as well as the cytokine-dependent serum components neopterin, beta-2-microglobulin (B2M), C-reactive protein (CPR), soluble IL-2-receptor (sIL-2R) and 2'-5'-oligoadenylate synthetase (2-5 OA) were assayed using ELISAs and RIAs. None of the samples tested contained measurable cytokine levels other than IL-2. A low and non-toxic dose of 300,000 U nIL-2 was already biologically active with induction of neopterin, B2M and sIL-2R. Dose-dependent changes peaked 24-48 h after application. The same patients were then enrolled in a phase II trial. Treatment in five of the patients was continued twice per week for 3 months with a biologically active dose of 300,000 U nIL-2 subcutaneously. Two of these patients as well as another five patients from the original group were treated with 1.0 million U nIL-2 subcutaneously, twice weekly for 3 months. Neither a biologically active but non-toxic dose of 300,000 U nIL-2, nor a toxic dose of 1.0 million U resulted in permanent clearance of hepatitis B early antigen (HBeAg).(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 2 therapy: current role in surgical oncological practice

The use of recombinant interleukin 2 (rIL-2) in clinical practice has opened up new and beneficial avenues in the treatment of certain malignant diseases. Although rIL-2 can stimulate a range of host antitumour defence mechanisms, only 30-40 per cent of patients who are treated will respond to such therapy as assessed by a reduction in tumour volume. The effect of rIL-2-based treatment schedules on delaying progression of disease and on overall survival in comparison with standard current treatments and chemotherapeutic regimens is not clear. Randomized clinical trials are required to evaluate precisely the role of rIL-2 in various therapeutic combinations and to ascertain the optimum therapeutic regimens for individual tumour types. Studies currently under way should provide more insight into the possible beneficial effects of immunotherapy with rIL-2. More basic research is required to ascertain how rIL-2 may produce its antitumour effects and why the therapeutic results obtained in humans have been so selective and less beneficial than those in experimental animals.

Clinical toxicity of interleukin-2

Interleukin-2 (IL-2) is increasingly used to treat patients with cancers refractory to conventional treatment. Flu-like syndromes are extremely frequent but usually mild. A variety of skin complications (mostly erythema and mucositis) have been reported. Life-threatening skin reactions have also been described. Acute reactivation of psoriasis can also occur. Immediate hypersensitivity reactions have so far not been described, but IL-2 treatment has been shown to predispose to acute hypersensitivity reactions to iodine-containing contrast media. Hypothyroidism is the major endocrine complication and antithyroid antibodies have been detected in approximately 50% of patients. Neurological and psychiatric disturbances with moderate or severe mental status changes are common and sometimes treatment-limiting. The occurrence of peritumoural oedema in patients with brain metastases can also be a major practical problem. Musculoskeletal disorders are transient and resolve spontaneously. The vascular leak syndrome is the most frequent and severe complication of IL-2 of which weight gain, generalised oedema, hypotension and impaired renal function are the main features. Even though a damaging effect on vascular endothelium cells by various cytokines released by activated lymphoid cells or mediated by non-lymphocyte-dependent factors has been proposed to be involved, the mechanism remains unclear. Other cardiovascular injuries, possibly life-threatening, including myocarditis, angina pectoris and myocardial infarction, can occur during the first days of treatment. Supraventricular arrhythmias are the most common rhythmic disorder. Decreases in myocardial contractility and haemodynamic pattern similar to those of septic shock have been encountered in most cases. Acute renal dysfunction is common but resolves with symptomatic management. Intrahepatic cholestasis with hyperbilirubinaemia is observed in most patients but permanent liver damage has not been described. Several cases of pancreatitis have been reported. Anaemia, thrombocytopenia, lymphocytopenia and eosinophilia are frequent and occur in most if not all patients. Some data suggest a high incidence of infectious complications, particularly in patients with surgically tunnelled catheters, but marked flu-like syndromes may be confounding. Finally, death directly related to IL-2 treatment has been noted in less than 1% of all patients. Investigations are under way to minimise IL-2 toxicity with varying dose regimens and combined treatments.

Clinical use of biologic response modifiers in cancer treatment: an overview. Part II. Colony-stimulating factors and interleukin-2

Colony-stimulating factors (CSFs) are hematopoietic growth hormones that stimulate the production, maturation, and function of white blood cells. The best studied are granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), both of which can be produced by recombinant DNA technology. Clinical indications for these agents include bone marrow failure secondary to administration of chemotherapeutic drugs or radiation, bone marrow transplantation, and a variety of congenital or iatrogenic neutropenias. Toxicity in usual clinical doses is mild, and consists mainly of bone pain and constitutional symptoms such as fever, headache, and myalgias. Interleukin-2 (IL-2) is a lymphokine that stimulates that multiplication of several types of killer cells. These cells can recognize and destroy foreign substances, such as tumors, without destroying normal cells. Major applications of IL-2 include treatment of patients with renal cell carcinoma, in whom the overall objective response rate is 15-30 percent, and malignant melanoma with response rates of about 18 percent. Combination therapy with other biologics and conventional cytotoxic drugs may increase IL-2's efficacy against these tumors. Toxicity is generally severe, but reversible. Hemodynamic toxicity, consisting of hypotension, edema, weight gain, and decreased renal function, is most characteristic. Suggestions are given for pharmacologic management of these and other IL-2 toxicities.

The immunotherapy of human cancer with interleukin 2: present status and future directions

Interleukin-2 (IL-2) is the principal soluble factor responsible for the proliferation of activated T cells. In animal models and humans, administration of IL-2 can induce regressions of established cancers. These antitumor effects may be partially mediated by cytotoxic effector cells activated by IL-2, including lymphokine-activated killer (LAK) cells and cytotoxic T lymphocytes. IL-2 has additional effects on other components of the cellular immune system, including B cells and macrophages, and induces secretion of other soluble mediators, including tumor necrosis factors (TNF) alpha and beta, and interferon-gamma. These effects may contribute to the antitumor activity of IL-2 as well as its dose-related toxicity. Multiple Phase I and II trials have been completed or are ongoing evaluating the clinical and biological effects of IL-2 given by diverse routes and schedules, both alone and in combination with infusions of ex vivo IL-2-activated autologous LAK cells. Other studies have begun to explore the potential for antitumor synergy when IL-2 is combined with the different interferons, TNF, monoclonal antibodies, and cytotoxic drugs. The biology, toxicity, and clinical activity documented in IL-2 clinical trials to date are reviewed, and prospects for future directions outlined.

Pathologic findings associated with interleukin-2-based immunotherapy for cancer: a postmortem study of 19 patients

The use of interleukin-2 (IL-2), either alone or in combination with lymphokine-activated killer cells, tumor infiltrating lymphocytes, or other immunotherapeutic agents has added a new list of alternatives to conventional antineoplastic regimens. Little information is available about the pathologic changes occurring in patients treated with these agents. In this study, we reviewed the necropsy materials from 19 patients, 12 men and 7 women, with a variety of malignancies including melanoma, renal cell carcinoma, gastrointestinal and pulmonary adenocarcinoma, and metastatic gastrinoma, who died after receiving IL-2-based immunotherapy. Death occurred at intervals ranging from less than 1 hour to 143 days following the last dose of therapy. All patients dying at or less than 43 days following cessation of therapy had lymphoid infiltrates of varying intensity in residual tumor. At necropsy, the major cause of death unrelated to the presence of metastatic tumor was bacterial sepsis. In addition, we found evidence of significant cardiac and pulmonary toxicity: two patients with acute myocardial infarction, one with and one without significant coronary artery disease, two cases of unexplained lymphocytic myocarditis, and one case of fatal pulmonary capillary plugging following an infusion of lymphokine-activated killer cells. Thus, not unlike other forms of therapy for cancer, IL-2-based immunotherapy does not appear to be without significant toxicity.

On radiation damage to normal tissues and its treatment. I. Growth factors

The first part of the review outlines the classical interpretation of radiation damage to normal organs based on dose-response relationships for clonogenic cell survival and tissue kinetics. Proliferative organization of critical cell lineages (three-compartmental or H-type and one-compartmental or F-type) is considered as an additional determinant in the development of overt radiation injury. This leads to testable predictions concerned with divergent outcomes of stimulation of cell proliferation after radiation exposure using polypeptide growth factors. The prediction of favourable effects of such stimulation in H-type lineages is borne out by recent experiments on treatment with cytokines of radiation-induced haemopoietic insufficiency. The second prediction of deleterious effects of proliferative stimulation in recently, heavily irradiated F-type cell lineages remains to be verified or refuted.