Hepatic and renal functions are the major determinants of drug elimination and have to be e xplored before administration of anti- cancer drugs. Renal dysfunction is easily assessed b y determining serum creatinine, measuring or calculating creatinine clearance, or most accu rately, by determining the clearance of radio-labeled EDTA. The impact of hepatic dysfuncti on on the drug elimination or metab- olism is more dif \201cult to estimate. Because of co mplex pathophysio- logical mechanisms of liver insuf \201ciency, hepatic enzymes and serum bilirubin levels are often poor indicators of metabolic activity. Alternative hepatic func tion tests have limited value in predicting pharmacokinetics of chemotherapeutic drugs: Indocyanine green (a marker of hepatic blood \202ow) (cid:2) (cid:2) Antipyrine (a substrate marker for cytochrome P450 activity) (cid:2) Lorazepam (a s ubstrate marker of hepatic glucuronidation) Practical considerations make these dynamic liv er functions inappro- priate for routine clinical practice. When metabolism of a drug is la rgely dependent on a unique catalytic enzyme, subpopulations of poor metabolizers may resul t from polymorphism in gene coding for the drug-metabolizing enzyme. Advancing age also represents a cause of pharmacokinetic variability of many drugs. Ageing is characterized by a combination of various physiological disorders, including reduction o f hepatic or renal blood \202ow, possible declines in microsomal activity, and frequent c o-medication. OHO-09(135-180) 11/16/02 11:20 AM Page 178 PRINCIPLES OF CHEMOTHERAPY 178 For some drugs, such as carboplatin, anthracyclines, and docetaxel, close relationships bet ween patient characteristics and drug clearance have been established. Then, priori adap tive dosing based on these characteristics is possible. For other drugs, such as methotrexa te, 6-mercaptopurine, and 5- \202uorouracil, dose optimization requires determination of p lasma concentrations in each patient in order to adjust subsequent doses or to modulate cur rent dose in case of continuous therapy. This approach \200\224 \200\230adaptive dosing wit h feed- back control \200\231 \200\224requires certain logistics which limit its use for al l drugs. Examples of dosing strategies for individual therapy Carboplatin Carboplatin is mainly eliminated by the kidney. Egorin \201rst estab- lished two relationships: (cid:2) First: between carboplatin clearance and measured creatinine clearance. (cid:2) Second: between the AUC and the percentage decrease in platelets following carboplatin administration as a single agent. By combining these, a formula was derived for individual dose cal- culation according to me asured creatinine clearance and desired platelet count at nadir. The concept of optimum AUC for carboplatin was demonstrated for treatment of ovarian and testicular cancers. Calvert developed a formula to allow a dose of carboplatin to be calculated in order to achieve a target AUC: Dose (mg) = AUC \227 (GFR + 25 ml/min) with GFR determined by isotopic measurement of 51Cr -EDTA clear- ance. The value of 25 ml/min corresponds to the mean non-renal clearance of ca rboplatin. The carboplatin target AUC must be chosen with reference to any other cytotoxics given in c ombination. Drugs (e.g. cyclophos- phamide) potentiate the hematological toxicity of carbop latin, but with others such as paclitaxel it is safe to administer an AUC similar to that o f carboplatin administered alone. Moreover, patients without prior exposure to chemotherapy may support a larger AUC than those who are heavily pre-treated. Anthracyclines and taxanes In the case of impaired hepatic function, guidelines have been p ro- posed for doxorubicin dosage reduction as a function of serum biliru- bin level: dose r eductions by 50%, 75%, or 100% are recommended when bilirubin exceeds 12, 30, or 50 mg/l. F or docetaxel, \201ve co- variables (age > 70 years, hypoalbuminaemia, elevation of (cid:3 )1-glyco- OHO-09(135-180) 11/16/02 11:20 AM Page 179 PHARMACOKINETICS/PHARMACODYNAMICS OF ANTI-CANCER DRUGS 179 protein, and raised ALT and AST) are predictive of reduced clearance. Since correlation was found between docetaxel clearance and risk of severe neutropenia, these parameters may all ow prediction of patients with high risk of toxicity and application of rational dose reduc tion. Methotrexate Monitoring of plasma drug concentration in patients receiving high- dose metho trexate is routinely performed. High levels 48 hours after the intravenous infusion and the reafter are associated with a risk of serious toxicity. For these patients with decreased m ethotrexate clear- ance and/or a large volume of distribution of the drug (generally due to the presence of a \200\230third space \200\231 \200\224pleural effusion or ascites), foli nic acid rescue is administered at a dosage adjusted according to methotrexate plasma level s. Mercaptopurine The effect of mercaptopurine is dependent on formation of the active 6-thiog uanine nucleotide (6-TGN) metabolites. This anabolic path- way competes with the catabolic pathway mediated by thiopurine methyltransferase. The latter enzyme expression is subject t o genetic polymorphism with about 10% of patients having intermediate activity and about 1 in 300 inheriting a de \201ciency who are exposed to prohibitive toxicity if standard merc aptopurine dosage is adminis- tered. The concentration of 6-TGN inside red blood cells has been shown to be an independent and important predictor of treatment outcome of patients ta king daily oral mercaptopurine. Although no de \201nite recommendation on how to individualize treatment can be given, mon itoring of erythrocyte 6-TGN should identify patients with a high-risk pharmacokinetic pro \201le (low levels of 6-TGN), allowing assessment of patient compliance. Summary Although prospective clinical studies comparing standard (in mg/m2) versus individu alized dosing have yet to be performed, it is likely that individualized dosing of some ant i-cancer drugs, based on pharmaco- kinetics, could increase the probability of tumor respon se and decrease the probability of major toxicity. In the absence of routine therapeutic dr ug monitoring, adjustment of the dose of subsequent treatment cycles according to the prese nce or absence of toxicity should be implemented more systematically. OHO-09(135-180) 11/16/02 11:20 AM Page 180 PRINCIPLES OF CHEMOTHERAPY 180 Further reading Cleton, F.Y. \200\230Chemotherapy: general aspects \200\231 in Peckham, M., Pinelo, M.M. a nd Veronesi, V. (eds.) Oxford Textbook of Oncology, pp. 445 \200\22353. OHO-10(181-188) 11/16/02 11:23 AM Page 181 Chapter 10 Hormone therapy Introduction 182 Types of endocrine therapy 183 Predictive indices of response 186 Resistan ce to hormone therapy 187 Controversies 188 OHO-10(181-188) 11/16/02 11:23 AM Page 182 HORMONE THERAPY 182 Introduction Hormones have been implicated in the development and behavior of many malignant tumors (inc luding vaginal, ovarian, laryngeal, pan- creatic, gastrointestinal, melanomas, and meningio mas). The best evidence that hormones maintain the growth of cancers relates to sex steroid hormones and tumors of their target organs, namely oestro- gens and progestins in breast a nd endometrial cancer and androgens in prostatic cancer. The effects of endocrine therapy are generally con \201rmed to target organs, and there ar e side-effects outside these sites. This accounts for the increased tolerability of this tr eatment in comparison with cyto- toxic chemotherapy. However, many tumors appear resistant to endocrine therapy, even at \201rst presentation, and more become insensitive during th e selective pressure of treatment and progression. Thus, most patients with breast and pros tate cancers die with hormone-independent disease. With this background it is important to outline: (cid:2) Different types of endocrine strategies and their relative advantages/ disadvantages. (cid:2) Predictive indices of response. (cid:2) Mechanisms of resistance. (cid:2) Controver sies and future expectations. OHO-10(181-188) 11/16/02 11:23 AM Page 183 TYPES OF ENDOCRINE THERAPY 183 Types of endocrine therapy Ablation of endocrine glands In men and premenopausal women the major sites of steroid horm one synthesis are the gonads. Castration decreases circulating testosterone in males by ove r 95% and oestrogens in premenopausal women by 60% (relative to follicular phase levels).Th ese endocrine effects produce bene \201ts in about 80% of men with metastatic prostate can cer and in 30 \200\22340% of unselected premenopausal women with advanced breast cancer. Oo phorectomy is rarely bene \201cial in post-menopausal women because the post-menopausal ov ary produces little estrogen. These response rates represent the gold standard against which to compare other forms of en docrine therapy. Hypophysectomy and adrenalectomy have been used in post-menopausal women w ith breast cancer. Whilst these may produce bene \201t in about one-third of cases, the pr ocedures do have signi \201cant morbidity and lack speci \201city, removing other classes of hormones in addition to sex steroids. The irreversible nature of surgical ablation of e ndocrine organs, when all patients cannot be guaranteed bene \201ts, has provided the impe tus to develop alternative drug-based therapies that are speci \201c, reversible, and self -limiting. Thus if therapy proves ineffective, drug withdrawal allows hormone levels to ret urn to normal with amelioration of side-effects. Agonists/supraphysiological doses of hormone This approach is epitomized by the use of gona dotrophin-relating hormone agonists (GnRHa or LHRHa). The gonadotrophins LH and FSH provide the stimulus for gonads to produce steroid hormones; in turn their synthesis and release f rom the pituitary is regulated by the hypothalamic factor GnRH (or LHRH). Highly potent ago nist ana- logues of GnRH have been synthesized by introducing unusual amino acids into the native peptide. When administered for short periods they cause a rapid release of gonadotro phins, but in the long term these agonists down regulate gonadotrophic receptors and desens itize the pituitary. As a result circulating gonadotrophins fall, the trophic drive to the gonads is abolished, and circulating sex hormones are reduced to castration levels. Depot f ormulations of LHRH agonists are available so that a single injection can maintain effectiv e medical castration over prolonged periods. The use of GnRH analogs in pre- menopausal wom en with breast cancer and men with prostate cancer has produced anti-tumor effects equivale nt to surgical castration. A similar mechanism of action underpins the response seen in hormone-dependent cancers foll owing use of pharmacological doses of steroid hormones such as: OHO-10(181-188) 11/16/02 11:23 AM Page 184 HORMONE THERAPY 184 (cid:2) Estrogen (diethyl stilboestrol). (cid:2) Progestogens (medroxyprogesterone and mege strol). (cid:2) Androgens (testolactone and \202uoxymesterone). Lower physiological doses of the same hormones may accelerate tumor growth. While down regulation of steroid hormone receptors occurs in target organs, other non-speci \201c effects can occur, and these agents may be associated with poor toxicity pro \201l es. Also, tumor \202are may occur at the start of treatment. Despite this they are of cli nical bene \201t e.g. high-dose progestogens for endometrial and breast cancer. Inhibition of steroid-producing enzymes This approach is best illustrated by inhibitors of aromatase or 5(cid:2)- reductase activity. The aromatase enzyme converts androgens to oestr ogens and is the last step of the synthetic cascade. Its inhibition represents the most spe ci \201c method of blocking estrogen produc- tion. Because estrogen biosynthesis can occur in non-endocrine tissue such as adipose tissue and malignant tumors themselves (par- ticul arly in post-menopausal women), aromatase inhibitors have the potential to suppress estroge n levels beyond that achievable by surgical ablation of classical endocrine organs. Two maj or types of inhibitors have been developed: (cid:2) Steroidal or type I inhibitors, which i nterfere with the attachment of androgen substrate to the catalytic site. (cid:2) Non-steroidal type II inhibitors, which interfere with the enzyme \200\231s cytochrome p450 prosthetic group. Early type II inhibitors such as aminoglutethimide were neither potent nor speci \201c, in hibiting other steroid-metabolizing enzymes that had a similar cytochrome p450 prosthetic g roup. Triazole drugs (anastrozole, letrozole, vorozole) are 2000-fold more potent than amin oglutethimide and have differential af \201nity towards aromatase cytochrome p450 with hig hly selective inhibition of estrogen bio- synthesis. These drugs can reduce circulating oes trogens in post- menopausal women to undetectable levels without in \202uencing other ster oid hormones. Amongst type I inhibitors, formestane and exemestane are thought to act as \200\230suicide \200\231 inhibitors, blocking aromatase irreversibly through their own metabolism into act ive intermediates by the enzyme; estrogen biosynthesis can only be resumed when aromatase m ole- cules are synthesized de novo. However, aromatase inhibitors may not in \202uence the growth of hormone-dependent tumors. Oestrogenic effects are mediated through non-classical oestrogens such as: OHO-10(181-188) 11/16/02 11:23 AM Page 185 TYPES OF ENDOCRINE THERAPY 185 (cid:2) Adrenal 5-androgens. (cid:2) Dietary phyto-oestrogens. Industrial pesticides. (cid:2) In terms of androgens, 5(cid:2)-dihydrostesterone has much greater bio- logical activity in the prostate than its precursor, testosterone. There has been interest in developing 5(cid :2)-reductase inhibitors such as \201nasteride. However, they appear more useful for beni gn prostatic conditions than for cancer. Steroid hormone antagonists These agents block hormone-mediated effects usually at the leve l of their receptors. Antagonists for oestrogens, progestins, and androgens have been devel oped. The most extensive experience relates to the use of the anti-estrogen, tamoxifen, in the treatment of breast cancer. Tamoxifen binds to the estrogen receptor and blocks the eff ects of endogenous oestrogens. Responses are more likely to occur in tumors that are estrog en receptor-positive. Tamoxifen incompletely blocks the trophic actions of estrogen and can demonstrate partial a gonist activity, especially when endogenous oestrogens are low. More potent \200\230pure \200\231 anti-oestrogens have therefore been developed, such as ICI182780 (Faslodex), which is a 7-alkyl amide analog of oestradiol and completely blocks the transcrip- tional activi ty of the estrogen receptor (by preventing receptor dimerization and shuttling). This drug produces clinical responses in patients with both acquired and inherent resistance to tamox ifen. However, pure anti-oestrogens may have more detrimental effects on bones and blood vessels than the partial agonist tamoxifen. Attention has therefore focused on Selective estrogen-R eceptor ModulatorS (SERMS), such as raloxi \201ne, which have target-site speci \201city for their anti-oestrogenic activity. Anti-androgens such as \202utamide and casodex have clinical ef \201cacy in the treatmen t of prostatic cancer. Anti-progestins such as RU-486 and onapristone have been used agains t breast and endometrial cancer. OHO-10(181-188) 11/16/02 11:23 AM Page 186 HORMONE THERAPY 186 Predictive indices of response Given that hormone therapy is not effective in all tumors, indiscrim- inate application of treatment exposes patients with resistant cancer to the side-effects of endocrine-deprivati on therapy and, more impor- tantly, delays other potentially bene \201cial treatment. Currently no marker correlates absolutely with endocrine depen- dency and the most widely-u sed predictor is the estrogen receptor (ER), in relation to breast cancers. Between 60 and 75% of breast cancers are ER-positive by biochemical assay or immunohisto- chemistry; two-t hirds of ER-positive tumors respond to hormone manipulation, compared with 5 \200\22310% of ER-negative tumors. The value of other markers such as the progesterone receptor in breast or endometrial cancer is less clear and measurement of the androgen receptor in prostatic cancer has not proved useful. Previous response to hormone manipulation is a useful clinical predictor for second-line en docrine therapy and suggests that pro- gression on hormone therapy does not equate with acq uisition of absolute endocrine resistance. OHO-10(181-188) 11/16/02 11:23 AM Page 187 RESISTANCE TO HORMONE THERAPY 187 Resistance to hormone therapy Resistance to hormone therapy may be primary or acquired during treatment. Two reasons for primary resistance are suggested: (cid:2) The tumor may not require hormones for growth. (c id:2) The tumor is hormone-dependent but endocrine therapy fails to reduce hormone levels below that needed for growth. Acquired resistance Induction of metabolic enzymes, reduces intra-cellular drug levels. (cid:2) (cid:2) Emergence of clones of hormone-dependent cells. (cid:2) Production of mitogens. Induction of growth factor receptors. (cid:2) (cid:2) Second messenger systems allowing transcription in presence of low level of hormones OHO-10(181-188) 11/16/02 11:23 AM Page 188 HORMONE THERAPY 188 Controversies Duration of adjuvant therapy If hormone deprivation therapy is not cytotoxic but cytostatic , thera- py would need to be given inde \201nitely. The counter argument is that resistanc e may be accompanied by a change in tumor phenotype induced by the continued presence of th e drug. Discontinuation of the treatment followed by another non-cross-resistant regime mig ht be more effective. Combination therapy Should endocrine therapies be given sequentially or in combination? Is combination more likely to achieve maximum cell kill and should this be implemented before resistance occurs? Clinical experience suggests that combined treatment may not justify its increased toxicity with the possible loss of second/third-line responses and some evi- den ce of adverse pharmacological interactions between drugs. Chemo-endocrine therapy Proponents suggest that endocrine therapy is a form of chemotherapy and since combination chemotherapy is bene \201cial there is good rea- son to use chemo-e ndocrine therapy. However, it can be argued that hormone therapy, by suppressing tumor cell growth, may give protection from chemotherapeutic agents which are most effective against replicating cells. OHO-11(189-204) 11/16/02 11:24 AM Page 189 Chapter 11 Immunotherapy of cancer Introduction 190 Active immunotherapy 191 Adoptive immunotherapy 199 Tumor vaccines 200 Gen e therapy 201 Summary 202 OHO-11(189-204) 11/16/02 11:24 AM Page 190 IMMUNOTHERAPY OF CANCER 190 Introduction Although new chemotherapeutic agents, increased doses, com- binations of drugs, or even hig h-dose ablative regimens have been used with some success, their use is ultimately limited by their non- speci \201c end-organ toxicity. So, investigators have explored strategies o f anti-neoplastic treatment with the potential to speci \201cally kill malignant cells, ci rcumventing tumor-cell resistance and using a dif- ferent mechanism from conventional chemo therapy. These so-called \200\230biological \200\231 therapies of cancer aim to produce an ti-tumor effect through the activation of defense mechanisms of the host or the administrat ion of natural substances. It was the development of molecular biology and hybridoma techno logy that made available the unlimited supply of appropriate reagents. The concept of a role for the immune response in the control or even eradication of cancer is not new. In fact, it was as early as in 1891 that William Coley reported tumor regressio n after stimulation of the patient \200\231s immune system by deliberately infecting cancer patients with erysipelas. But it was not until the 1960s that the \200\230immune surveill ance theory of cancer \200\231 was introduced by Burnet. According to this theory, immune s ystem cells continuously patrol the body, eliminating newly mutated malignant cells and pro tecting against the development of cancer. This vigilance would only be circumvented if the immune sys- tem was depressed or malignant cells became more aggressive. This hypothesis provided the background for the development of cancer immunotherapy, which encompasses all the therapeutic manipulations of the immune system, utilizing any immune-re lated agents, such as cytokines, cellular or humoral products, vaccine prepa- rations, and transfected genes, with or without immuno-potentiation by drugs or other agents. OHO-11(189-204) 11/16/02 11:24 AM Page 191 ACTIVE IMMUNOTHERAPY 191 Active immunotherapy Active immunotherapy is the immunization of the patient with mate- rials that elicit an imm une reaction capable of eliminating/delaying tumor growth. It includes the administration o f non-speci \201c stimu- lators of the immune system, such as the bacillus Calmette \200 \223Gu rin (BCG) and cytokines. Unfortunately, cancer usually grows in an immunosuppressed envi- ronment and, therefore, no n-speci \201c cancer vaccines, with the iden- ti \201cation of tumor-associated antigens and the ability to genetically modify tumor cells, offers the promise of a speci \201c, ac tive immunotherapy. Passive immunotherapy of cancer includes the administration of materials that have the abil ity to mediate anti-tumor response directly or indirectly. This material could be antibodie s, used either native or conjugated to a toxic agent, or cells (lymphocytes or macrophages) . Bacillus Calmette \200\223Gu rin (BCG) The anti-neoplastic effect of the live attenuated t uberculosis vaccine, bacillus Calmette \200\223Gu rin (BCG), was reported by Pearl in 1929 . Later, Mathe and co-workers demonstrated a survival bene \201t in animals with hematolog ical malignancies treated with BCG. Unfortunately, the clinical studies that followed did n ot con \201rm any effectiveness of BCG systemic administration in patients with various ma lignancies (lymphocytic leukemia, melanoma, lung cancer). Currently, only two applications of BCG in cancer patients are successful: Intralesional administration into cutaneous metastases in patients with melanoma Intravesic al instillation for the treatment of patients with super \201cial bladder cancer (cid:2) (cid:2) Immunotherapeutic action of BCG (cid:2) Activates \200\224macrophages \200\224T lymphocytes \200\224 B lymphocytes \200\224natural killer cells Induces local type II immunological responses via interleukins (IL- 4, IL-1, IL-10) (cid:2) (cid:2) Bacterial surface glycoproteins attach to epithelial cells and act as antigens OHO-11(189-204) 11/16/02 11:24 AM Page 192 IMMUNOTHERAPY OF CANCER 192 Inhibits tumor-cell motility via BCG \200\224 \201bronectin (cid:2) \200\224tumor interaction BCG is the most effective intravesical agent for the prophylaxis of Ta and T1 super \201ci al bladder cancer, with a 38% reduction of recurrence rate. It can also achieve a complete response rate of 60% or more in stage Ta or T1 residual bladder cancer, although it is gene rally prefer- able to resect all visible tumors when possible, prior to beginning treatment . Immunotherapy, in the form of BCG, is the only approved intraves- ical treatment for CIS (c arcinoma in situ), with an average complete response rate of 72% (vs < 50% for chemotherapy ). The optimal dose and schedule of administration of BCG varies from patient to patient: the proposed intravesical dose is between one hundred million (1 \227 108) and one billion (1 \227 1010) colony forming units (CFU), but responses have been reported with doses as low as 10 million CFU or 1 mg BCG. Many patients (up to 90%) experience symptoms of cystitis, with dysuria, haematuria, mild f ever, and urinary frequency. It is advisable to withhold BCG administration to patients wit h gross haematuria, because the risk for absorption and major systemic BCG toxicity is incr eased. The most serious complication of BCG therapy is sepsis. It is mediated by traumatic catheterization with bleeding, severe cystitis, bladder biopsy, or transurethral resection of bladder tumor. Sepsis from gram-negative bacillae may occur following instrumentation of the genitourinary tract. Nevertheless, treatment must be initiated on the basis of medical history of BCG instillati on and of clinical suspicion: patients typically, but not invariably, develop: (cid:2) High fever (cid:2) Rigors (cid:2) Hypertension (cid:2) Mental confusion (cid:2) Disseminated in travascular coagulopathy (cid:2) Respiratory failure Jaundice (cid:2) Leukopenia (cid:2) Identi \201cation of BCG DNA with techniques of molecular biology may prove useful in the future. Cytokines Cytokines are soluble proteins that mediate the interactions between the cells an d their extracellular environment, in both an autocrine and paracrine manner. They exert th eir biological effect in a wide range of tissues, but mainly on cells of the haematopoietic and immune lineage. OHO-11(189-204) 11/16/02 11:24 AM Page 193 ACTIVE IMMUNOTHERAPY 193 Although several cytokines have been identi \201ed and characterized, their biological rol e is not fully understood because their physiology is particularly elaborate, since a given cytokine can both promote and inhibit tumor growth. How the cytokine will act depends on i ts concentration, the type of the tumor, and the temporal stage of the tumor \200\223host r elationship. Several cytokines promise to be of therapeutic importance in oncology, including: Interleukins (IL) (cid:2) (cid:2) Tumor necrosis factor (TNF) (cid:2) Erythropoietin (cid:2) Colony-stimulating facto r (CSF) and interferons (IFNs) Interferons The interferons (IFN(cid:2)-, (cid:3), and (cid:4)) are a family of proteins th at are produced by the immune system in response to viral infection. They have anti-viral, anti-microbial, anti-proliferative, and immuno- modulatory activity. Anti-tumor effects of IFNs: (cid:2) Direct cytostatic activity Interfere with cell metabolism proliferation (cid:2) (cid:2) Modulate oncogene expression (cid:2) Enhance tumor-associated surface antigens (cid :2) Enhance cytotoxicity of natural killers (NK), macrophages, and T lymphocytes (cid:2) Reduce tumor neovascularization (cid:2) Promote differentiation of malignant cells to less aggressive types. Interferon \200\223(cid:2)(IFN-(cid:2)) IFN-(cid:2)is the treatment of choice for hairy-cel l leukemia (HCL), with a 90% response rate in the peripheral blood and 40% normalization of the bone marrow. The standard dose is 2 \227 106 U/m2 given three times a week, for 6 \200\22312 months, either intramuscularly or subcuta- neously. It may induce partial or, le ss frequently, complete remission. Patients who relapse can be successfully retreated. The combination of IFN-(cid:2) with the purine analog 2-chlorodeoxyadenosine may be more effect ive for HCL patients. IFN-(cid:2) also has a \201rst-line role in the management of chronic myeloid leukemia (C ML): IFN-(cid:2) (5 \227 106 U/m2 daily) exerts a marked effect on the white blood count, with 50 \200\22375% hematological remission, while prolonged administration can induce comp lete cytogenetic eradication, suppressing the Philadelphia chromosome- positive clone. IFN- (cid:2) monotherapy increases the median survival OHO-11(189-204) 11/16/02 11:24 AM Page 194 IMMUNOTHERAPY OF CANCER 194 from 3 to 5 years, while its combination with other treatment modali- ties increases furthe r the clinical response. Several phase III studies have demonstrated progression-free and overall survival when IFN- (cid:2) (3 \200\22310 MU/m2 subcutaneously)was added to conventional chemotherapy to multip le myeloma patients. Up to 50% of patients with nodular (follicular) non-Hodgkin \200\231s lym- phoma, refractory to conventional chemotherapy, may respond to IFN-(cid:2). Cutaneous T-cell lymphoma is another malignancy where responses of >50% can be achieved with IFN-(cid :2)(6 \227 106 U/m2 daily). With regard to solid tumors, responses can be seen in 10 \200 \22320% of patients with renal cell carcinoma (RCC). They usually are partial and last for 6 \200\2238 months, although complete remissions have also been reported. Responses are mor e often in patients with a low tumor burden, good performance status, and lung metastases o nly. Relatively high doses of IFN-(cid:2)(10 \200\22320 \227 106 U/m2 three times per week ) have to be given. IFN-(cid:2) monotherapy has a moderate anti-tumor activity in malig- nant melanoma patients , but when combined with chemotherapy (dacarbazine) response rates are as high as 20%. Resp onses are usually partial, but they provide a survival bene \201t. IFN-(cid:2), alone or c ombined with zidovudine, may induce tumor responses in Kaposi \200\231s sarcoma patients, w hile IFN-(cid:2)monotherapy has been used in carcinoid tumors. IFN-(cid:2)has also been giv en intravesically, intraperitonally, intrapleurarly, and intralesionaly for the loco-region al treatment of cancer. Clinical uses of IFN-(cid:2): (cid:2) Hairy-cell leukemia (HCL) (cid:2) Chronic myeloid leu kemia (CML) (cid:2) Multiple myeloma (cid:2) Non-Hodgkin \200\231s lymphoma (cid:2) Cutaneo us T-cell lymphoma (cid:2) Renal cell carcinoma (cid:2) Malignant melanoma (cid:2) Kaposi \200\231s sarcoma (cid:2) Carcinoid tumors IFN-(cid:3)and IFN-(cid:4) Despite the fact that only IFN-(cid:2) is currently in routine c linical use, IFN-(cid:3)and IFN-(cid:4)have also some anti-tumor effect. Clinically, they h ave been used in patients with: (cid:2) Multiple myeloma (cid:2) HCL (cid:2) CML (cid:2) Re nal cell carcinoma OHO-11(189-204) 11/16/02 11:24 AM Page 195 ACTIVE IMMUNOTHERAPY 195 (cid:2) Melanoma (cid:2) Ovarian cancer (cid:2) Bladder cancer There is not enough data to support any advantage over IFN-(cid:2), or with the concomitant administration of more than one IFN. IFN-(cid:2), alone or in combination with tamoxifen, has been used also in breast cancer patients, with poor results. However, the combination of IFN-(cid:2) and TNF has been shown to be particularly effective in preclinical models. Clinically, this com- bination has been used in the treatment of me lanoma and sarcoma using isolated limb perfusion. IFN-(cid:2) has been used also in combina - tion with IL-2, in patients with peritoneal carcinomatosis, and with 5- \202uorouracil, in patients with advanced colorectal cancer. It syner- gistically enhances LAK cell activit y of IL-2. Phase I/II clinical trials are currently ongoing. Toxicity of IFNs The major side-effects include \202u-like symptoms (fever, chills, heada che, malaise), which can be relieved with paracetamol or pred- nisolone. Other toxicities i nclude: (cid:2) Anorexia (cid:2) Fatigue (cid:2) Rashes (cid:2) Gastrointestinal complaints (cid:2) Lethargy (cid:2) Thrombocytopenia (cid:2) Elevation of liver function tests Tolera nce to IFN-(cid:2)increases with prolonged administration and all side-effects are reversib le when treatment is discontinued. IFNs represent an anti-neoplastic agent, effective for some malig- nancies resistant to conventional chemotherapy. Interleukin-2 (IL-2) IL-2, a lymphokine produced by activated T cells (Th1), plays a pivota l role in immune modulation, enhancing the growth of activated T cells, the proliferation o f lymphoid cells, and the migration of lym- phocytes from the peripheral blood. Anti-tumor activity of IL-2 includes the capacity to lyse fresh tumor cells, the regression of dis- ta nt metastases in murine models, and the in vivo release of other members of the cytokines f amily. IL-2 has been widely applied in the management of patients with advanced cancer. The system ic administration of high doses of IL-2, alone or in combination with lymphokine-activated killer (LAK) cells, activated ex vivo, may induce objective responses in a small OHO-11(189-204) 11/16/02 11:24 AM Page 196 IMMUNOTHERAPY OF CANCER 196 proportion of patients with renal cell carcinoma (5 \200\22315%) or metasta- tic melanoma ( <15%). Responses have also been demonstrated in patients with acute myeloid leukemia. These studies were per- formed in patients of poor prognosis, with advanced and refractory disea se. IL-2 can be given intravenously at doses from 72 000 to 720 000 IU/kg every 8 hours. Toxici ties associated with IL-2 administration include: (cid:2) Flu-like syndrome (cid:2) Capilla ry leak syndrome (cid:2) Severe hypotension (cid:2) Arrhythmia (cid:2) Angina (cid:2) Respi ratory distress (cid:2) Somnolence (cid:2) Anemia (cid:2) Thrombocytopenia (cid:2) Multi-or gan malfunction (cid:2) Toxic fatalities in up to 10% of patients In melanoma, administrati on of IL-2 alters the biodistribution of dacarbazine due to enhanced capillary permeability , resulting in syn- ergy. IFN-(cid:2) enhances IL-2 lymphocyte proliferation and IFN-(cid:2 ) /IL-2 combination therapy is undergoing clinical assessment in patients with renal cell c arcinoma and melanoma. Tumor necrosis factor (TNF) TNF is an important mediator of the in \202ammatory response, being involved in stress conditions, cachexia, and endotoxin shock. It is mainly produced b y monocytes, activated macrophages, and T cells. It induces the expression of MHC class I a nd II antigens, as well as adhesion molecules responsible for leukocyte migration and accum u- lation. TNF (mainly TNF-, has been used in various clinical trials, mostly in patients with advance d melanoma and sarcoma. Results have been disappointing, with <5% response rate. Loco-regio nal administration (intraperitoneally, intravesically, intralesionally) seems more promis- ing, but its clinical use is limited by the severe side-effects which include: (cid:2) Acut e fever (cid:2) Anemia (cid:2) Thrombocytopenia (cid:2) Hepatotoxicity OHO-11(189-204) 11/16/02 11:24 AM Page 197 ACTIVE IMMUNOTHERAPY 197 (cid:2) Cytochrome P450 depression (cid:2) Transient impairment of renal function (cid:2) C entral nervous system toxicity, especially in the elderly Local administration of rTNF and of TNF encapsulated liposomes could be used in the future to circumvent the problems of tox icity. Data show synergy between TNF and conventional chemothera- peutic agents such as cyclophosp hamide, doxorubicin, and cisplatin. TNF may reverse cisplatin resistance. On the other hand , cisplatin and cyclophosphamide may act as biological modulators by increasing TNF binding to the cell surface. Monoclonal antibodies Although the management of cancer by exploiting properties distin- gu ishing neoplastic and normal cells has always been an attractive concept, it was the develo pment of hybridoma technology and the resulting tumor-associated monoclonal antibodies (mAb s) that offered new prospects for this strategy. Some of the applications of mAbs in oncolo gy are now part of everyday diagnosis (i.e. immuno- histochemistry, radio-immunodetection). With regard to cancer therapeutic modalities, unconjugated or native mAbs can activate comp onents of the complement and of cytolytic cells and result in tumor lysis, with a mechanism known as Antibody-Dependent Cellular Cytotoxicity (ADCC). Several studies have been conduc ted, mainly in patients with hematological malig- nancies. The responses achieved were gene rally poor and of short duration: circulating malignant cells were reduced, but with little effect on lymph node or bone marrow disease. Since the cytotoxic effect of the mAbs was minimal, they have been used as carriers of more potent agents such as conventional cytotoxic drugs, radionuclides, liposomes, and toxins, to achieve speci \201c deliv- ery at the tumor sites and therefore reduced host toxicity. Another approach is to use mAbs-enzymes conjugates to catalyze various sub- strate conversi ons at the tumor. The pro-drug is administered after the conjugate has localized to the sur face of the malignant cells and cleared from the circulation. These approaches are currently undergoing clinical evaluation; the major problem seems to b e in the immune response elicited by murine antibodies, known as HAMA (Human Anti-Mouse Ant i- globulin response). Nevertheless, it is expected that the evolution of genetic engineeri ng and the subsequent production of single-chain, chimaeric and humanized antibodies and of fusion proteins will over- come this problem. Other limiting factors are the low antibody uptake by the tumor, the antigenic heterogeneity of the tumor, the poor tumor penetration, and the poor stability of the immuno-conjugates in vivo. OHO-11(189-204) 11/16/02 11:24 AM Page 198 IMMUNOTHERAPY OF CANCER 198 In conclusion, the use of mAbs as targeting devices for cytotoxic agents is a very attracti ve approach for tumor immunotherapy. However, there are still several complex issues to be resolved before they become part of the routine practice in oncology. OHO-11(189-204) 11/16/02 11:24 AM Page 199 ADOPTIVE IMMUNOTHERAPY 199 Adoptive immunotherapy The demonstration that the cell-mediated immune response is crucial in the rejection of all ogeneic and syngeneic tumors has prompted the use of cells with anti-tumor activity in pati ents with malignancies \200\224an approach known as adoptive immunotherapy of cancer. Several strategies have been applied to generate cells with reactivity to tumors, the most common being the production of lymphocyte- activated killer (LAK) cells that can lyse fresh tumor cells, by incu- bating human peripheral blood lymphocytes with IL-2, ex vivo. The ex act mechanism of recognition and destruction of tumors by LAK cells is not fully understood . Trials in renal cell carcinoma and melanoma patients did not reveal any therapeutic advan tage in the administration of LAK plus IL-2, compared to monotherapy with IL-2. In an alternative approach of adoptive immunotherapy, tumor- in \201ltrating lymphocytes ( TILs), that can recognize tumor-associated antigens, have been isolated from human tumors a nd administered to patients with advanced melanoma, with a response rate (PR + CR) of 25 \200\22335%. Recently, genetically manipulated TILs have been produced, with the transducti on of the gene encoding either the neomycin phosphotransferase or tumor necrosis factor. OHO-11(189-204) 11/16/02 11:24 AM Page 200 IMMUNOTHERAPY OF CANCER 200 Tumor vaccines Hepatitis B virus (HBV) vaccine is a widely used, very effective vaccine against hepatocell ular carcinoma, while studies are in progress to develop vaccines against Epstein \200\223B arr virus, which is closely linked to the development of: (cid:2) Burkitt \200\231s lymphom a (cid:2) Nasopharyngeal carcinoma (cid:2) Non-Hodgkin \200\231s lymphomas Other obvious ca ndidates for development of an anti-tumor vaccine are the human papilloma virus (HPV) and t he human retrovirus, HTLV, which are causative agents for several human malignancies.