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Background ESR1 mutations have been identified as mechanism for endocrine resistance and are also associated with a decreased overall survival. We assessed ESR1 mutations in circulating tumor DNA (ctDNA) for impact on outcome to taxane-based chemotherapy in advanced breast cancer patients. Methods ESR1 mutations were determined in archived plasma samples from patients treated with paclitaxel and bevacizumab (AT arm, N = 91) in the randomized phase II ATX study. Samples collected at baseline (n = 51) and at cycle 2 (n = 13, C2) were analyzed using a breast cancer next-generation sequencing panel. This study was powered to detect a benefit in progression-free survival (PFS) at six months for patients treated with paclitaxel/bevacizumab compared to historical trials with fulvestrant. PFS, overall survival (OS), and ctDNA dynamics were exploratory analyses. Results PFS at six months was 86% (18/21) in patients with an ESR1 mutation detected and 85% (23/27) in wildtype ESR1 patients. In our exploratory analysis, median progression-free survival (PFS) was 8.2 months [95% CI, 7.6–8.8] for ESR1 mutant patients versus 8.7 months [95% confidence interval (CI), 8.3–9.2] for ESR1 wildtype patients [p = 0.47]. The median overall survival (OS) was 20.7 months [95% CI, 6.6–33.7] for ESR1 mutant patients versus 28.1 months [95% confidence interval (CI), 19.3–36.9] for ESR1 wildtype patients [p = 0.27]. Patients with ≥ two ESR1 mutations had a significantly worse OS, but not PFS, compared to those who did not [p = 0.003]. Change in ctDNA level at C2 was not different between ESR1 and other mutations. Conclusions Presence of ESR1 mutations in baseline ctDNA might not be associated with inferior PFS and OS in advanced breast cancer patients treated with paclitaxel/bevacizumab.

Boven E, Ossenkoppele GJ. Targeted therapieen tegen kanker. Huisarts Wet 2011;54(5):266–71. Er zijn de afgelopen jaren veel nieuwe medicijnen tegen kanker op de markt gekomen die specifieke signaleringsroutes in tumorcellen gericht blokkeren. Naast deze zogeheten ‘targeted’ therapieen is ook een aantal oude kankermedicijnen in een nieuw jasje gestoken, waardoor zij gemakkelijker kunnen worden toegediend of minder bijwerkingen hebben. De nieuwe therapieen hebben de overleving van kankerpatienten sterk verbeterd, en huisarts zal deze nieuwe of vernieuwde geneesmiddelen dan ook vaker dan vroeger tegenkomen in de dagelijkse praktijk. Dit nascholingsartikel schetst het werkingsmechanisme van de targeted therapieen, geeft een globaal overzicht wanneer en bij welke tumoren zij worden ingezet en laat zien welke bijwerkingen de huisarts zou kunnen tegenkomen.

We have previously reported that amifostine potentiates the anti-tumour activity of carboplatin in mice. The present study was carried out in well-established human ovarian cancer xenografts OVCAR-3, A2780 and FMa grown subcutaneously in the nude mouse. It was found that a single dose of amifostine resulted in a higher increase in the anti-tumour activity of carboplatin than three doses of amifostine. A single dose of amifostine increased the AUC (area under the curve) values of total platinum in plasma ultrafiltrate (30.1 vs 18.2 microM x h), liver (307.7 vs 236.4 nmol g(-1) x h), kidney (500.8 vs 368.3 nmol g(-1) x h) and OVCAR-3 tumour tissue (184.0 vs 146.8 nmol g(-1) x h). Despite this increase in total platinum, a decrease in platinum (Pt)-DNA adduct levels was observed in liver, kidney and bone marrow, which was significant in liver. In tumour tissue an insignificant increase in Pt-DNA adduct levels, specifically the Pt-GG adduct, was observed after treatment with a single dose of amifostine, which may explain the increase in anti-tumour activity. The increase in the AUC of total platinum was probably caused by a reduction in body temperature, which was most severe after three doses of amifostine. The extreme hypothermia may be the reason that three doses of amifostine resulted in less potentiation of the efficacy of carboplatin.

A high-performance liquid chromatographic (HPLC) assay is described for the determination of the new antitumour drug N-benzoylstaurosporine (CGP 41 251; I) and four of its potential metabolites in micro-volumes (100 microliters) of plasma. After addition of an internal standard, the compounds were isolated from plasma by liquid-liquid extraction with diisopropyl ether. Chromatography was carried out using a 5 microns LiChrospher C-18 end-capped column (125 x 4.0 mm i.d.) and binary gradient elution with acetonitrile and a triethylamine-containing phosphate buffer (pH 3.6) as solvents. Fluorimetric detection was performed with excitation and emission wavelengths set at 286 and 386 nm, respectively. The absolute recovery was more than 98% for all of the investigated compounds. The limit of detection (LOD) for I and three metabolites was 0.1 ng ml-1 and the lower limit of quantitation (LLQ) was 0.2 ng ml-1 in 100 microliters of plasma. The LOD and LLQ for the fourth metabolite was 0.25 and 0.5 ng ml-1, respectively. The between-day and within-day precisions were always < 15% for all the analytes. A limited pharmacokinetic study in mice treated and with I demonstrated that the method is appropriate for this purpose.

The selective modulation of carboplatin [diammine(1,1-cyclo-butanedicarboxylato)platinum(II)]-induced myelotoxicity was investigated in mice, using the protective agent WR2721 [S-2-(3-aminopropylamino)ethyl-phosphorothioic acid, ethiofos]. In female BALB/c mice, WR2721 (200 mg/kg intraperitoneally, i.p.) partly prevented the reduction of in vitro proliferation of whole bone marrow cells and non-adherent cells when administered at different time points relative to 90 mg/kg carboplatin (i.p.). Protection was highest when WR2721 was administered 5 min prior to carboplatin. In vitro proliferation of whole bone marrow cells and non-adherent cells in liquid culture increased from 15% of control for carboplatin alone to 45% when WR2721 was administered 5 min prior to carboplatin. However, WR2721 did not significantly prevent the loss in clonogenic capacity of early hematopoietic progenitors in the bone marrow, as determined by a bilayered soft agar colony forming units assay. In nude mice, bearing well-established subcutaneous human ovarian carcinoma xenografts OVCAR-3, WR2721 (200 mg/kg i.p.) 5 min prior to intravenous carboplatin allowed a 1.5-fold increase in the maximum tolerated dose of carboplatin as determined by overall weight loss. WR2721 alone did not affect tumour growth. However, WR2721 had a potentiating effect on the tumour growth inhibition of a standard dose of carboplatin in this model. Minimal tumour volume compared to control (T/C) decreased from 9.4% with carboplatin alone to 2.2% with WR2721 5 min prior to the same dose of carboplatin. Specific growth delay (SGD) increased from 7.4 to 10.3. With the 1.5-fold increased, equitoxic dose of carboplatin in combination with WR2721, the antitumour activity was only slightly further increased (T/C = 1.4%, SGD = 10.5).

Antibody-directed enzyme prodrug therapy (ADEPT) may improve the therapeutic index of cytostatic agents. We compared two prodrugs, epirubicin-glucuronide (Epi-glu) and doxorubicin-spacer-glucuronide (Dox-sp-glu), for their cytotoxicity on activation by a monoclonal antibody-enzyme conjugate bound to tumor cells. The results showed that the prodrugs were 10 (Dox-sp-glu) and 100 (Epi-glu) times less toxic than the parent drugs against OVCAR-3 cells. This difference was a result of the hydrophilic property of the prodrugs resulting in a reduced cellular uptake. The enzyme-catalyzed hydrolysis of Dox-sp-glu by E. coli-derived beta-glucuronidase (GUS) (Km 500 microM, Vmax 21,000 mumol/min/g) was much more efficient than that of Epi-glu (Km 10 microM, Vmax 40 mumol/min/g). Incubation of OVCAR-3 cells with an enzyme-immunoconjugate prepared from monoclonal antibody 323/A3 and E. coli-derived GUS before treatment with prodrugs completely restored the cytotoxicity of the prodrugs to the level of the parent drugs.

The selective targeting of tumors by enzymes conjugated to monoclonal antibodies (mAb) may be an ideal approach to convert relatively nontoxic prodrugs into active agents at the tumour site. We used the anti-carcinoembryonic antigen mAb BW431/26 conjugated to alkaline phosphatase (AP) and phosphorylated etoposide (etoposide-P) as a prodrug to study the feasibility of this concept. Etoposide was phosphorylated with POCl3. Quantitative hydrolysis of etoposide-P to etoposide occurred within 10 min in the presence of AP. BW431/26 and AP were conjugated using a thioether bond. The AP conjugate retained 93% of its calculated activity. 125I-labelled AP conjugate did not show a reduction of immunoreactivity as determined by a cell-binding assay. SW1398 colon cancer cells were used to analyse the cytotoxicity of etoposide and etoposide-P. Etoposide (IC50 22 microM) was 100 times more toxic than etoposide-P (20% growth inhibition at 200 microM). Pretreatment of the cells with BW431/26-AP prior to etoposide-P exposure resulted in a dramatic increase in cytotoxicity (IC50 70 microM). The pharmacokinetics and tumour-localizing properties of BW431/27 and the AP conjugate were assessed in nude mice bearing SW1398 tumours. BW431/26 showed excellent tumour localization (10% of the injected dose/g tissue retained from 8 h to 120 h), whereas the AP conjugate showed a reduced tumour uptake (3%-0.3% of the injected dose/g tissue at 8-120 h), a faster clearance from the circulation and a high liver uptake. Radiolabelled AP showed a similar pharmacokinetic profile to the AP conjugate. Gel filtration analysis of blood, liver, and tumour samples indicated good stability of the conjugate.

Eight human ovarian cancer lines grown in nude mice were used to compare the activity of doxorubicin, epirubicin, mitoxantrone and menogaril. The tumour lines were different in histological subtype, tumour doubling time and sensitivity to doxorubicin. The compounds were administered intravenously at the maximum tolerated dose twice with one week in between when tumours measured 50–150 mm3. Growth inhibition greater than 50% was obtained for doxorubicin in 8 8 , for epirubicin in 4 8 , for mitoxantrone in 5 8 and for menogaril in 2 8 tumour lines. In MRI-H-207, doxorubicin was the only drug able to induce complete remission. Compared with doxorubicin, mitoxantrone and menogaril were given in proportionally higher doses than those administered to patients, but did not result in superior antitumour activity.

Three patients with advanced renal-cell cancer were treated with sunitinib 50 mg daily for 4 weeks followed by a rest period of 2 weeks because of progressive disease. The first patient developed stomatitis and a painful blister on his foot. Complaints disappeared after temporary discontinuation of treatment. Re-treatment at a lower dosage was successful until disease progression. The second patient developed skin discolouration, fatigue, fever and diarrhoea. After treatment was interrupted shortly, these symptoms disappeared and sunitinib was recommenced at a lower dosage. The patient went on to develop stomatitis, thrombocytopenia and hypertension (treated with amlodipine). She subsequently had hand-foot syndrome. She died due to brain metastases. In the third patient symptoms of disease returned during the rest period, because of which he received a reduced dosage of sunitinib on a continuous base. He developed diarrhoea which disappeared after a short interruption of the drug. Sunitinib has been approved for the treatment of advanced renal-cell cancer and imatinib-resistant gastro-intestinal stromal tumours. This novel targeting molecule is a tyrosine-kinase inhibitor of vascular endothelial growth-factor receptors, platelet-derived growth-factor receptors and c-Kit. It can induce adverse events that differ from those observed in treatment with conventional cytotoxic agents. The adverse effects are reduced by lowering the dosage and in the rest period within the treatment cycle.

Ewing's sarcoma and peripheral primitive neuroectodermal tumours (PNET) are rare tumours and closely related. They occur most often in children and adolescents. Few studies have been published on treatment outcome in adult patients.We performed a retrospective analysis of patients aged16 years who were primarily treated at our university hospital for Ewing's sarcoma or PNET. In general, treatment consisted of long-term multiagent chemotherapy, interrupted by individualised local treatment consisting of surgery and/or radiotherapy. We reviewed clinical features and outcomes to present our experience with Ewing's sarcoma and PNET in adults.From 1979 to 2002, 27 patients with Ewing's sarcoma (20) or PNET (7) were treated. There were 22 men and 5 women, with a median age of 25 years (range 17-49). Ten patients presented with metastases predominantly in lungs (4) or bones (6). Combination therapy consisted of chemotherapy (27), surgery (16) and radiotherapy (16). After a median follow-up of ten years, 14 patients have died (toxicity = 2, progressive disease = 12) and 13 patients are alive and free of disease. Five-year overall survival was 58%. All four patients with bone metastases died, while all five patients presenting with lung metastases are disease-free.The five-year overall survival of 58% in this small series on adult patients is in line with paediatric study outcomes. Patients with lung metastases may even be cured by multimodality therapy. We therefore strongly advocate referral of patients with this rare disease to a specialised oncology centre.

A major focus of this year's American Association for Cancer Research (AACR) meeting was the microenvironment of the tumor and tumor angiogenesis, as well as the development of drugs that affect tumor growth by use of extratumoral targets. Other areas of interest were advances in chemoprevention, cancer vaccines, gene therapy approaches and drug-resistance features. As before, many novel compounds affecting tumor cells were introduced, either being analogs of standard cytostatic agents or directed against new cellular targets. Mechanisms of action were further unraveled and emphasis was put on the various signals within a tumor cell to enter cell death through apoptosis. Molecular biology technology was dedicated to the development of tests to measure gene expression in small tissue samples.

A major focus of this year's meeting was the plenary session on the use of high-dose chemotherapy for the treatment of metastatic breast cancer and the incorporation of adjuvant treatment for poor prognosis primary breast cancer. Four abstracts on large randomized collaborative trials in the US, Scandinavian countries and South Africa were presented in this plenary session and discussed by Dr R Livingston (University of Washington, USA), Dr G Hortobagyi (University of Texas/MD Anderson Cancer Center, USA) and Dr K Antman (Columbia University, USA). In general, high-dose chemotherapy followed by (autologous bone marrow) stem cell support has not yet shown improvement in overall survival and has contributed to substantial side-effects when compared to standard chemotherapy in breast cancer. In most trials, however, follow-up was short and long-term analysis may change the current conclusions. Other issues of interest included early clinical trials on agents affecting angiogenesis, signal transduction inhibitors, gene therapy and cancer vaccines.

This year's meeting covered a vast number of subjects of which a few warrant specific discussion due to current interest. Research activities are expanding in the potential use of anti-angiogenic and antivascular targeting agents for treatment of cancer. Studies on the mechanisms of action of this wide variety of agents remain the focus of attention. A large series of abstracts was dedicated to apoptosis and approaches to stimulate tumor cells to enter the apoptotic death pathway. Insight into DNA damage and repair is increasing, as well as measures to circumvent cellular drug resistance. Another subject to mention is the generation of dendritic cells for immunotherapy. And last, but not least, presentations concerning the state-of-the-art of microarray technology not only included encouraging data, but also reviewed the problems encountered when using patient's tumor samples for analysis.

The flavonoid 7-monohydroxyethylrutoside (monoHER) can protect against doxorubicin-induced cardiotoxicity. A drawback of monoHER therapy would be the relatively high dose needed to obtain complete protection (500 mg/kg in mice). Therefore, we synthesized a series of new compounds with improved antioxidant properties. After characterization of antioxidant activity, cardioprotection in vitro, and possible toxic properties in hepatocytes, we selected Frederine for additional investigations in vivo. In the present study, it was found that this compound did not induce weight loss or (gross) organ changes in mice in a treatment schedule of 170 mg/kg i.p., 5 times/week during 2 weeks. We recorded the electrocardiogram telemetrically in mice during and 2 weeks after the combined treatment with doxorubicin (4 mg/kg, i.v.) and 5 times Frederine (68 mg/kg, i.p.; equimolar to 100 mg/kg monoHER) for 6 weeks. Complete protection against doxorubicin-induced cardiotoxicity was found, indicating that Frederine is at least 5 times more potent than monoHER. Frederine did not have a negative influence on the antiproliferative effects of doxorubicin on A2780, OVCAR-3, and MCF-7 cells in vitro and on OVCAR-3 xenografts grown in nude mice when administered 5 min before doxorubicin (8 mg/kg i.v.) and 4 days thereafter with an interval of 24 h. It can be concluded that we succeeded in designing a better cardioprotector than monoHER. Therefore, Frederine merits further investigation as a possible protector against doxorubicin-induced cardiotoxicity in cancer patients.

A glucuronide doxorubicin prodrug N-[4-doxorubicin-N-carbonyl (oxymethyl) phenyl] O-beta-glucuronyl carbamate (DOX-GA3) has been developed to improve the antitumor effects of doxorubicin (DOX). The prodrug was originally designed to be activated into drug by human beta-glucuronidase (GUS) released from tumor cells in necrotic areas of tumor lesions. The aim of this study was to further improve the antitumor effects of DOX-GA3 by means of antibody-directed enzyme prodrug therapy (ADEPT). We thus investigated if the administration of an enzyme-immunoconjugate prepared from the pancarcinoma Ep-CAM specific monoclonal antibody (MAb) 323/A3 and beta-glucuronidase would result in improved antitumor effects because of additional enzyme localization in tumor tissue. In vitro, the prodrug DOX-GA3 was found to be 12-times less toxic than the parent drug DOX in a human ovarian cancer cell line. Immunospecific and complete activation of the prodrug took place when the cells were pretreated with 323/A3-beta-glucuronidase conjugate. In nude mice bearing s.c. human ovarian cancer xenografts (FMa) the maximum tolerated dose (MTD) of DOX-GA3 (500 mg/kg weekly x 2) was much higher when compared with that of DOX (8 mg/kg weekly x 2). In mice bearing well-established FMa xenografts, the standard treatment of DOX at the MTD (8 mg/kg weekly x 2) resulted in a tumor growth inhibition of 67%. Treatment with DOX-GA3 at a single dose of 500 mg/kg resulted in a better tumor growth inhibition of 87%. The combination of DOX-GA3 (500 mg/kg) with 323/A3-mGUS conjugate and anti-GUS MAb 105, to clear circulating conjugate, improved the antitumor effect even further to 98%. At the lower dose of 250 mg/kg DOX-GA3 tumor growth inhibition (34%) was not better than that of DOX. The combination, however, of DOX-GA3 at 250 mg/kg and 323/A3-mGUS conjugate plus MAb 105 again greatly improved the antitumor effect (growth inhibition of 93%). DOX given at 8 mg/kg weekly x 2 did not result in tumor regressions. As a result of ADEPT, the number of regressions of tumors improved from 0 out of 12 to 9 out of 11 at a dose of 250 mg/kg DOX-GA3. At the higher prodrug dose (500 mg/kg) the number of regressions improved from 2 out of 12 to 9 out of 10 as a result from the addition of enzyme-immunoconjugate. Our studies show that the efficacy of the widely used anti-cancer agent DOX may be improved by using the prodrug DOX-GA3, in combination with the tumor-specific enzyme-immunoconjugate 323/A3-mGUS and a conjugate clearing antibody.

BNP1350, 7-[(2-trimethylsilyl)ethyl]-20(S)-camptothecin, is a novel semi-synthetic, highly lipophilic, silicon-containing camptothecin and an inhibitor of topoisomerase I. It has been supercomputer engineered for superior oral bioavailability, superior lactone stability, broad anti-tumor activity, increased potency and insensitivity to Pgp/MRP/LRP drug resistance. We determined the efficacy of BNP1350 in experimental human colon cancer and compared its anti-tumor effects with those of CPT-11/SN-38. We also determined a possible influence of Pgp, MRP and LRP on the efficacy of BNP1350. The in vitro anti-proliferative capacity of the compounds using various exposure times was assessed in five colon cancer cell lines and indicated that BNP1350 was similarly effective or slightly more potent than SN-38. Four cell lines of other origin with sublines expressing Pgp, MRP and/or LRP showed that BNP1350 was significantly more effective than SN-38 (p0.05) and that the activity of BNP1350 was not reduced in multidrug-resistant cells. For in vivo experiments, BNP1350 was given 1.0 mg/kg i.p. or 1.5 mg/kg p.o. daily x 5 and CPT-11 20 mg/kg i.p. daily x 5 being equitoxic schedules in nude mice bearing s.c. human tumor xenografts. The schedules were studied in colon cancer xenografts COLO320, COLO205 or WiDr as well as in two Pgp-positive xenografts 2780AD and BRO/mdr1.1 and the parental Pgp-negative A2780 ovarian cancer xenografts and BRO melanoma xenografts. Growth inhibition of50% was obtained for BNP1350 given i.p. in six out of the seven xenografts studied. BNP1350 was similarly effective when given i.p. or p.o. CPT-11 was as effective as BNP1350, except in BRO and BRO/mdr1.1 xenografts. Pgp expression in xenografts in vivo confirmed that there was no negative influence on the efficacy of BNP1350. In conclusion, BNP1350 shows a broad spectrum of activity in experimental human tumors and is a suitable candidate for oral treatment of cancer.

The purpose of this study was to determine the influence of impaired renal and liver function on the pharmacokinetics and pharmacodynamics of lobaplatin in cancer patients. A total of 25 patients with advanced solid tumors not amenable for standard treatment entered the study. Patients had normal organ function or an impaired liver or renal function (two levels). The starting dose of lobaplatin was 50 mg/m2 i.v. given every 3 weeks. The blood and urine of all patients were sampled for the determination of (ultrafilterable) platinum, intact lobaplatin, creatinine, and blood cell counts. No objective responses were recorded. Five patients experienced no change and received 4-10 cycles (median, 6 cycles) of lobaplatin. The extent and duration of hematological toxicity were worse in patients with impaired renal function. Thrombocytopenia was most prominent; grade 4 toxicity was observed in 15 patients in the first two cycles of treatment. The concentration-time curves of ultrafilterable platinum and intact lobaplatin revealed almost identical patterns. The elimination of ultrafilterable platinum [final half-life (t1/2 final) = 131+/-15 min; clearance (Cl) = 125+/-14 ml/min/1.73 m2] was much faster than that of total platinum (t1/2 final = 6.8+/-4.3 days, CI = 34+/-11 ml/min/1.73 m2). No pharmacokinetic differences were observed between patients with normal organ function and those with an impaired liver function within the investigated range. An impaired renal function resulted in an increase of the t1/2 final due to a decrease of the total body Cl that resulted in a higher exposure of the body to the drug. The calculated creatinine Cl was linearly correlated with the total body clearance of ultrafilterable platinum (r = 0.91), which resulted in the dosage formula D = AUCinfinity (1.1 Cl(CrU) + 16), in which D represents dose, AUC represents area concentration-time curve, and Cl(CrU) represents creatinine Cl. The thrombocyte surviving fraction correlated well with the AUC value of ultrafilterable platinum (r = 0.72). It can be concluded that the hematological toxicity and the pharmacokinetics of lobaplatin are strongly affected by renal function. The total body Cl of ultrafilterable platinum correlated well with the creatinine Cl and the thrombocyte surviving fraction. In patients with renal function, represented by a creatinine clearanceor =30 ml/min/1.73 m2, the derived dosage formula will enable us to calculate the dose that is expected to lead to an acceptable extent of thrombocytopenia in a patient with a given renal function. Prospective studies with larger groups of patients are needed to prove the value of this dosage formula.

Neoadjuvant chemotherapy improves survival in patients with locally advanced breast cancer (LABC). Usually three to four cycles of conventional-dose neoadjuvant chemotherapy are administered prior to local therapy, and another three cycles thereafter. In an attempt to improve results, we increased the dosages and applied GM-CSF, which, besides being a hematopoietic growth factor, has become increasingly known for its immunostimulatory effects, which might enhance the antitumor effect.Forty-two patients with stage IIIA or IIIB breast cancer were treated with doxorubicin (A) (90 mg/m2) and cyclophosphamide (C) (1,000 mg/m2) at three-weekly intervals. In the second and fourth cycle a 10% dose reduction of both agents was applied. On the second day GM-CSF 250 micrograms/m2/day was started and given for 10 days. Initially, some patients were treated withor = four cycles, but as the study progressed and toxicity appeared tolerable, six cycles were given whenever possible. After the chemotherapy, patients underwent surgery and postoperative radiotherapy.The response rate for the whole group to AC was 98% (95% confidence interval 94%-100%), with a clinical complete response rate of 50% (95% confidence interval 35%-65%). Six patients had a pathological complete response. Median follow-up from the start of chemotherapy is 49 months (range 10-100). The disease-free survival (DFS) at three years is 57% and the overall survival (OS) at three years is 79%. There is a significant trend for improved DFS (p = 0.0000) and OS (p = 0.0002) with increasing number of cycles.The results of the present study with neoadjuvant dose-intensive AC chemotherapy and GM-CSF compare favorably with previous studies in patients with LABC. This is most apparent in patients who received six cycles of neoadjuvant chemotherapy. We hypothesize that these encouraging results are probably related to the prolonged presence of the primary tumor, and to the long-term administration of GM-CSF with the primary tumor and axillary lymph nodes in situ. Therefore, a randomized study is warranted. We already initiated an international randomized trial in patients with LABC in order to answer two questions. First, does prolonged neoadjuvant chemotherapy result in an improved DFS and OS in comparison with the conventional approach, and secondly, what is the effect of GM-CSF in this approach in comparison with G-CSF?

CPT-11, a semi-synthetic derivative of camptothecin, was investigated for its activity in panels of 15 human ovarian-cancer lines and 10 human soft-tissue sarcoma lines grown s.c. in nude mice. Various factors were analyzed that may be of influence on the extent of tumor-growth inhibition induced by CPT-11. At equitoxic doses, CPT-11 was more effective in the daily x5 schedule than the weekly x2 schedule, although a 2-fold higher dose was administered in the weekly x2 schedule. Since i.p. and i.v. injections were similarly effective, the selected treatment schedule was 20 mg/kg i.p. daily x5, starting when tumors measured approximately 150 mm3. Growth inhibition ofor = 75% was obtained in 8/15 human ovarian-cancer lines and in 6/10 human soft-tissue sarcoma lines. A weak correlation was found between topoisomerase-I mRNA in xenograft tissues and sensitivity to CPT-11. Relative topoisomerase-I expression was highest in MRI-H-207 and WLS-160 xenografts, in which CPT-11 was able to induce cures of all tumors. The high efficacy in the 2 panels of human tumor lines suggests over-prediction of its potential clinical activity in these tumor types. The difference in efficacy of CPT-11 between species may be related to the metabolism of the drug, since CPT-11 is converted more efficiently into SN-38 in mice. In addition, mice may be less sensitive to SN-38-induced side-effects. On the basis of the preclinical data, frequent administration of lower doses of CPT-11 should be considered in order to increase response rates in the clinic.

The radionuclide 186Re has favorable physical characteristics for use in radioimmunotherapy, including the emission of beta-particles of a high-energy and a low-abundance of gamma-emission. The gamma-emission, in particular, is ideal for tumor imaging and poses less hazards to the patient and the medical personnel when compared with the gamma-emission of the widely used radionuclide 131I. In the present study, we determined whether 186Re-labeled monoclonal antibody 323/A3 may be better suited for the treatment of ovarian cancer than 131I-323/A3.We compared the biodistribution and the efficacy of 186Re- and 131I-labeled 323/A3 in nude mice bearing s.c. the human ovarian cancer xenografts FMa, OVCAR-3 and Ov.Pe. 186Re was conjugated to 323/A3 with the use of the S-benzoylmercaptoacetyltriglycine (S-benzoyl-MAG3) chelate.A molar ratio of Re-MAG3:323/A3 of 3:1 did not affect the integrity and the pharmacokinetic behaviour of the MAb. The tumor uptake and the retention of 186Re- and 131I-labeled 323/A3 were comparable, but the cumulative absorbed radiation dose in the tumor delivered by 186Re-323/A3 was 1.3-fold higher than that of 131I-323/A3. When mice were treated with equivalent radionuclide doses, the tumor growth inhibition induced by 186Re-323/A3 was similar or slightly better when compared with the efficacy of 131I-323/A3. When mice were treated with radionuclide doses that were adjusted to obtain equal cumulative absorbed radiation doses in the tumor for both conjugates, 131I-323/A3 was slightly more effective in the inhibition of the growth of FMa and OVCAR-3 xenografts.The favorable physical characteristics of 186Re as well as its efficacy when conjugated to a MAb indicate 186Re as an attractive radionuclide in radioimmunotherapy of ovarian cancer patients.

This study was conducted to determine whether the cytotoxic agent cisplatin (CDDP), also known as a radiosensitizer, can improve the efficacy of the 131I-labeled monoclonal antibody (MAb) 323/A3 in the treatment of experimental human ovarian cancer.Nude mice bearing well-established subcutaneous FMa, OVCAR-3, or Ov.Pe xenografts were injected twice with a 2-week interval either with a bolus of CDDP, 131I-323/A3, or with a combination of both modalities. CDDP was injected at various timepoints when combined with 131I-323/A3. The efficacy of the treatment was expressed as the specific growth delay (SGD). The growth inhibitory effect of the combination was characterized to detect additivity or synergism, using the mean relative tumor volumes at 2, 4, and 6 weeks after the last injection as endpoints.The efficacy of 131I-323/A3 was superior to that of the maximum tolerated dose (MTD) of CDDP (6 mg/kg) in all three xenografts. The addition of CDDP to 131I-323/A3 could increase the growth inhibition in the CDDP-responsive FMa and OVCAR-3 xenografts, but not in Ov.Pe xenografts. Although this improved antitumor effect was additive rather than synergistic, the combination was more effective when compared with that of the MTD of each of the modalities alone. The time interval between the administration of a bolus injection of CDDP and 131I-323/A3 had no effect on the extent of growth inhibition in OVCAR-3 xenografts.The addition of CDDP to 131I-323/A3 resulted in an additive inhibitory effect on the growth of CDDP-responsive xenografts. As the combination of radioimmunotherapy and CDDP was more effective in the inhibition of the tumor growth when compared with that of the MTD of each of the modalities alone, this treatment may therefore be considered of use in patients with ovarian cancer responsive to CDDP.

The epithelial glycoprotein 40 (EGP40) is an important target in the clinic for radioimmunolocalization and monoclonal antibody (MAb)-mediated therapy of cancer. We determined which tumor-related factors (including antigen distribution and density, vascularization and perfusion) were involved in the uptake of the anti-EGP40 MAb 323/A3 in 4 different human ovarian cancer xenografts grown s.c. in nude mice. The reactivity pattern of 323/A3 in all xenografts in vitro was similar and showed a strong and homogeneous distribution of the EGP40 antigen. FMa xenografts, however, showed the highest uptake of 323/A3 in vivo, which was 5.5-, 6.2- and 10.0-fold higher than that in OVCAR-3, Ov.Pe and Ov.Sh xenografts, respectively. FMa xenografts contained 2.1- to 3.5-fold more antigen per gram protein when compared with the antigen content of the other xenografts. FMa and Ov.Sh xenografts demonstrated a better vascularization pattern, whereas Ov.Pe and OVCAR-3 xenografts were moderately to poorly vascularized. FMa xenografts were also better perfused, as was shown by a 1.6- to 1.8-fold higher uptake of the (99m)Tc-labeled blood flow marker hexamethylpropyleneamine oxime (HMPAO). The tumor uptake of the non-specific MAb E48 was 2.2- to 11.2-fold lower when compared with that of 323/A3, but the sequence of uptake was similar (FMaOVCAR-3 = Ov.PeOv.Sh), indicating the lowest extravasation of MAbs in Ov.Sh xenograft tissue. Since both the antigen content and the perfusion appeared to be important factors of influence on the tumor uptake of 323/A3, attempts were made to manipulate these determinants to improve the tumor uptake. Neither gamma-interferon nor 5-fluorouracil were able to increase EGP40 expression in human ovarian cancer cells in vitro. Treatment of tumor-bearing mice with the calcium-antagonist flunarizine did not result in an improved perfusion, although a slight increase in the initial tumor uptake of 323/A3 was observed in Ov.Sh-bearing mice. Our results illustrate the relative contribution of various tumor-related factors that determine the usefulness of a MAb for imaging and therapy of cancer.

CPT-11, a new semisynthetic derivative of camptothecin, is active in a number of tumor types in the clinic, including colon cancer. CPT-11 is a drug that is converted into the active metabolite SN-38 by a carboxylesterase. Experiments were performed to obtain more insight in the cellular characteristics in 5 unselected human colon-cancer cell lines that account for the differential sensitivity to CPT-11 and SN-38. In vitro, the sensitivity to CPT-11 and SN-38 was highest in LS174T and COLO 320 cells, intermediate in SW1398 cells and lowest in COLO 205 and WiDr cells. SN-38 was 130 to 570 times more active than CPT-11. CPT-11 induced complete remissions in 6 out of 12 COLO 320 tumors grown as subcutaneous xenografts, but was not effective in WiDr tumors. The cellular carboxylesterase activity did not relate to the sensitivity to CPT-11. The enzyme activity was higher in normal mouse tissues, i.e., serum and liver, than in COLO 320 or WiDr xenografts, indicating that tumor carboxylesterase is of minor importance for CPT-11 efficacy. The topoisomerase-1 mRNA expression in tumor cells was not predictive of the antiproliferative effects of CPT-11 or SN-38. We observed a positive relationship between the DNA topoisomerase-1 activity and the cellular sensitivity to carboxylesterase-activated CPT-11 (r = 0.75, p0.1) as well as to SN-38 (r = 0.89, p0.05). The higher topoisomerase-1 activity in COLO 320 cells and tumors when compared with that in WiDr cells and tumors reflected the differences in sensitivity to the drug(s). In conclusion, the DNA topoisomerase-1 activity was the best determinant for CPT-11/SN-38 sensitivity in this panel of unselected human colon-cancer cell lines.

Gemcitabine (2',2'-difluorodeoxycytidine, dFdC, LY188011) is a new deoxycytidine analog with preclinical antitumor activity in solid tumors from murine and human origin. Of particular importance is the fact that the therapeutic effects of gemcitabine at the maximum tolerated dose level are dependent on the administration schedule. This paper describes the sensitivity pattern of gemcitabine in human head and neck squamous cell carcinoma, ovarian carcinoma, and soft tissue sarcoma, all growing as xenografts in athymic nude mice. The drug was injected intraperitoneally in various schedules at equitoxic, maximum tolerated dose levels, resulting in a reversible weight loss that varied between 5% and 15%. Generally, it was found that treatment with 120 mg/kg gemcitabine, injected four times at 3-day intervals, was more effective than the schedules of daily (five times 2.5 to 3.5 mg/kg) or weekly (two times 240 mg/kg) injections. Other workers have shown that this 3-day interval schedule also was active in human pancreas and lung carcinoma xenografts. Additional experiments were performed on normal mice bearing the colon 26-10 murine colon carcinoma. The effect of a continuous intravenous infusion system was investigated by giving two injections of 15 mg/kg gemcitabine for 24 hours at a 7-day interval. Interestingly, the efficacy of treatment increased dramatically with this infusion schedule, producing complete remissions in most tumors. In conclusion, our data on the effect of gemcitabine in animal tumor models indicate that (1) the time interval between push injections is important when intermittent schedules are used and (2) continuous infusions over a 24-hour period can be very effective in in vivo models.

The staurosporine derivative, N-benzoylstaurosporine (CGP 41 251; I), is a protein kinase C inhibitor that has been selected for phase I clinical evaluation in cancer patients. We have developed a selective and sensitive assay of the drug and three potential metabolites in human plasma. The method is based on reversed-phase high-performance liquid chromatography with fluorescence detection. The sample pretreatment involves liquid-liquid extraction with diisopropyl ether with recoveries over 88%. The limit of detection and limit of quantitation of the parent compound and two metabolites were 0.5 and 1.0 ng/ml, respectively. For the third metabolite the limit of detection and limit of quantitation were 1.0 and 2.0 ng/ml, respectively. Linear calibration lines were obtained over the range of 1-1000 ng/ml. The between-day and within-day precisions were < 7.1% for all the analytes. In plasma the compounds were stable for at least one month if stored at -30 degrees C or below. The applicability of the method for in vivo studies has been demonstrated in a pharmacokinetic study in rat receiving 0.5 mg/kg of the drug as an intravenous bolus injection. Compound I and two metabolites were detected.

In the evaluation of soil contamination dispersion of contaminants via groundwater plays an important role. RISC-TRANSPORT is a’ simple’ user-friendly computer model for calculating the transport of contaminants in the saturated zone of the soil. The model was developed within the framework of the RISC (=Risk Identification of Soil Contamination) project. The scope of this project was the development of a framework for risk assessment and priority ranking (Smit & Goldsborough, 1994).

Summary Background The EORTC New Drug Development Office has initiated a multicenter collaborative program to evaluate the use of human tumor xenografts to predict phase II clinical activity. A first study confirmed the efficacy of doxorubicin and inactivity of amsacrine against human tumor xenografts (Boven et al., Cancer Res: 52, 5940, 1992). In the follow-up study reported here, the activities of cisplatin, AZQ (diaziquone), pazelliptine and retelliptine have been evaluated against a panel of 40 established tumor lines grown subcutaneously in nude mice. Design The xenografts used represent carcinomas of the breast, colon, head + neck, ovary, small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC) and melanoma. Drugs were administered intravenously on days 0 and 7. Doses were for cisplatin 5 mg/kg, AZQ 3–7 mg/kg, pazelliptine 20–80 mg/kg and retelliptine 6–12.5 mg/kg and were selected to give a median loss of about 10%–15% body weight. Results When activity was defined as a specific growth delay > 1 and a tumor growth inhibition > 50%, then cisplatin demonstrated activity in 15 of 40 xenografts tested (3 of 5 breast, 1 of 6 colon, 0 of 5 head + neck, 2 of 6 NSCLC, 4 of 7 SCLC, 1 of 5 melanoma and 4 of 6 ovarian cancers); AZQ was active in 23 of 38 xenografts (2 of 3 breast, 2 of 7 colon, 4 of 5 head + neck, 3 of 6 NSCLC, 6 of 6 SCLC, 2 of 5 melanoma, 4 of 6 ovarian cancers); pazelliptine was active in 2 of 38 xenografts (1 of 5 breast cancers, 1 of 5 melanoma) while retelliptine was active in 1 of 39 xenografts (a breast cancer xenograft) tested. Conclusions These results are reasonably consistent with the clinical activity of cisplatin, but overpredict the clinical efficacy of AZQ. Since pazelliptine and retelliptine are investigational compounds, the clinical phase II studies will provide a prospective test for this model. The results of the present study and the previous one indicate that the human tumor xenograft model could be suitable for predicting the activity of novel compounds to be developed for treatment of cancer patients.

Sequential immunoscintigrams were used to describe the relative distribution and kinetics of 8 mg 131I-labeled human IgM monoclonal antibody 16.88 in 20 patients with colorectal cancer. The results show that the initial activity was higher and the clearance rate was faster (P0.05) from the left ventricle and liver than from most organs. In bone marrow the reverse was observed (P0.05). The biological half-life of 131I(-16.88) in tumor tissue (range 35.4-47.5 h) was longer (P0.01) than that in normal tissue (30.2-41.9 h). The image contrast ratio between liver metastases and background increased from 0.8 to 1.3 and for lesions outside the liver from 1.1 to 1.6. The estimated effective dose equivalent was 0.12 mSv/MBq. A second infusion 2 weeks after the first with the addition of unlabeled 16.88 up to 1000 mg for improvement of tumor tissue uptake was not of clinical relevance.

Summary Background The new cytostatic agent taxol has clearly demonstrated its effectiveness in ovarian cancer patients. The synthesis of drugs related to taxol could overcome its limited natural supply and may have additional benefits, such as greater efficacy or better solubility. Taxotere (RP 56976, NSC 628503) is such a compound. We investigated the drug for its antitumor activity in human ovarian cancer xenografts Materials and methods Five human ovarian cancer lines were selected with respect to differences in histological subtypes, growth rates and chemosensitivity to conventional cytostatic agents. Tumors were implanted as fragments s.c. into both flanks of female nude mice (Hsd: athymic nude-nu). Treatment was started in groups of 5-8 mice at the time mean tumor volume measured 50-150 mm3. Taxotere was injected i.v. weekly × 2. Drug efficacy was expressed as the maximum percentage of growth inhibition of treated tumors as compared to control tumors. Results At the maximum tolerated dose of 15-20 mg/kg for weekly i.v. × 2 injections, taxotere induced a mean weight loss of 10%–15% of the initial weight within 2 weeks after the first injection. The maximum percentage of growth inhibition obtained was ≥ 50% in 4/5 lines and ≥90% in 3/5 lines. In 2 lines, taxotere appeared more effective than cisplatin, cyclophosphamide or doxorubicin, drugs studied previously at maximum tolerated doses in the same tumor lines. Conclusion Our findings in human ovarian cancer xenografts hold promise for the efficacy of taxotere in this type of disease in the clinic.

In a European joint project carried out in 6 laboratories a disease-oriented program was set up consisting of a panel of 7 tumor types, each represented by 4 to 8 different human tumor lines, for secondary screening of promising anticancer drugs. Human tumor lines were selected on the basis of differences in histology, growth rate, and sensitivity to conventional cytostatic agents. Xenografts were grown s.c. in nude mice, and treatment was started when tumors reached a mean diameter of 6 mm in groups of mice where at least 6 tumors were evaluable. Drugs were given at the maximum tolerated dose. For evaluation of drug efficacy, median tumor growth curves were drawn, and specific growth delay and treated/control x 100% were calculated. Doxorubicin (8 mg/kg i.v. days 1 and 8) was effective (treated/control50%, and specific growth delay1.0) in 0 of 2 breast cancers, 1 of 3 colorectal cancers, 2 of 5 head and neck cancers, 3 of 6 non-small cell lung cancers, 4 of 6 small cell lung cancers, 0 of 3 melanomas, and 3 of 6 ovarian cancer lines. Amsacrine (8 mg/kg i.v. days 1 and 8) was not effective, while datelliptium (35 mg/kg i.p. days 1 and 8) was active against 2 of 6 small cell lung cancer lines. Brequinar sodium (50 mg/kg i.p. days 1-5) showed efficacy in 4 of 5 head and neck cancers, 5 of 8 non-small cell lung cancers, and 4 of 5 small cell lung cancer lines. The project has been shown to be a feasible approach. Clinical activity for doxorubicin and inactivity for amsacrine against solid tumor types was confirmed in the human tumor xenograft panel. Additional anticancer drugs will be studied in the European joint project to further define the reliability of this novel, promising screening approach.

2-(3-Aminopropylamino)ethylphosphorothioic acid (WR2721; ethiofos) was shown to selectively protect nontumor tissues from cis-diamminedichloroplatinum(II) (cisplatin)-induced toxicity, when administered 30 min prior to the platinum drug. Selectivity of protection by WR2721 is probably due to the preferential formation and uptake of the thiol metabolite 2-(3-aminopropylamino)ethanethiol (WR1065), which can inactivate toxic platinum-species inside the cell. We investigated the protective potential of WR2721, when administered at different time points relative to cisplatin. BALB/c mice treated with WR2721 (200 mg/kg i.p.) either 30 min or 5 min prior to cisplatin (i.p.) allowed a 2.2-fold increase in cisplatin dose to 19 mg/kg before the occurrence of nephrotoxicity as expressed by an increase in plasma urea. A small part of the protection could be ascribed to the mannitol (200 mg/kg), present in the formulated WR2721. WR2721 (200 mg/kg) 30 min after 14.5-16-mg/kg cisplatin did not offer any protection against the rise in plasma urea. WR2721 (200 mg/kg) 5 min before 19-mg/kg cisplatin did not cause liver toxicity (increase in serum glutamic pyruvic transaminase or serum glutamic oxaloacetic transaminase). Furthermore, WR2721 (200 mg/kg) 5 min prior to cisplatin did not reduce antitumor activity in nude mice bearing well-established human ovarian cancer xenografts. Under protection of WR2721, the dose of cisplatin could be increased by a factor of 1.6 to 8 mg/kg (administered twice weekly), resulting in an increased antitumor activity.

5006 Background: To identify genetic markers in the pharmacokinetic and pharmacodynamic pathways of sunitinib that predispose for development of toxicities; thrombocytopenia, leukopenia, mucosal inflammation, hand-foot syndrome and ‘any toxicity according to Common Terminology Criteria > grade 2.’ Methods: A multicenter pharmacogenetic association study was performed in 219 patients treated with single agent sunitinib. A total of 31 single nucleotide polymorphisms in 12 candidate genes, together with several non-genetic variants, were analyzed for a possible association with toxicity. In addition, genetic haplotypes were developed and related to toxicity. Results: The risk for leukopenia was increased when the G-allele in CYP1A1 2455A/G (OR = 6.24; p = 0.029) or the T-allele in FLT3 738T/C (OR = 2.8; p = 0.008) were present or CAG in the NR1I3 (5719C/T, 7738A/C, 7837T/G) haplotype (OR = 1.74; p = 0.041) was absent. ‘Any toxicity > grade 2’ prevalence was increased when the T-allele of VEGFR-2 1191C/T (OR = 2.39; p = 0.046) or a copy of TT in the ABCG2 (-15622C/T, 1143C/T) haplotype (OR = 2.63; p = 0.016) were present. The risk for mucosal inflammation was increased in the presence of the G-allele in CYP1A1 2455A/G (OR = 4.03; p = 0.021) and the prevalence of hand-foot syndrome was increased when a copy of TTT in the ABCB1 (3435C/T, 1236C/T, 2677G/T) haplotype (OR = 2.56; p = 0.035) was present. Conclusions: This exploratory study suggests that polymorphisms in specific genes encoding for metabolizing enzymes, efflux transporters and drug targets are associated with sunitinib related toxicities. A better understanding of genetic and non-genetic determinants of sunitinib toxicity should help to optimize drug treatment in individual patients. [Table: see text]

A non-randomized study was carried out in the Free University Hospital, Amsterdam, to investigate the (hematologic) toxicity and antitumor response of patients with advanced breast cancer treated with intensive chemotherapy in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF). Of 11 patients with an inoperable or metastasized breast cancer, 5 were treated with doxorubicin 75 mg/m2 + cyclophosphamide 750 mg/m2 intravenously every 3 weeks and 6 patients with 90 and 1000 mg/m2 respectively. When in a preceding cycle a significant hematologic toxicity was observed, this patient was treated in the subsequent cycle with the same dose of chemotherapy in combination with GM-CSF 250 micrograms/m2/day from day 2-12 as a continuous infusion. Bone marrow depression was diminished in the presence of GM-CSF. This was apparent from a milder decline of the number of neutrophilic granulocytes, reduction of the neutropenic period and a more rapid recovery of the neutrophil number. A transient eosinophilia and a mild monocytosis were also observed. GM-CSF did not improve erythrocyte and thrombocyte counts. The efficacy of GM-CSF was less pronounced in the group of patients with the highest dose of chemotherapy. GM-CSF was associated with malaise, fever and a small decrease of blood pressure, which in combination with a frequently occurring anemia and the side-effects of high dose chemotherapy, resulted in a substantial toxicity. In 9/11 patients an objective tumor regression was noted. GM-CSF stimulated the recovery of granulocytes after intensive chemotherapy. Treatment of a small group of patients with advanced breast cancer with intensive chemotherapy resulted in a high antitumor response.

Twenty colorectal cancer patients were given an intravenous injection of human IgM monoclonal antibody (MAb) 16.88 (8 mg) conjugated to 131I for tumor localization. After a 2-week interval, a second injection with 200, 500, or 1000 mg of unlabeled antibody added was given to groups of five patients each. at the end of the 2-hour infusion, 66% of the radioactivity remained in the circulation. Blood clearance of the 131I-labeled MAb 16.88 was biphasic with a mean half-life (T1/2 alpha) of 12 hours and T1/2 beta of 45 hours. Clearance rate was 0.09 L/hour. More than 90% of the 131I in serum was protein bound, with an immunoreactive fraction of 80% in the first 48 hours. Size exclusion chromatography indicated no degradation products other than 131I in serum and urine. The urinary excretion rate of 131I increased to 1.5% of the dose per hour at 24 hours, with 50% of the dose excreted in 34 hours. The pharmacokinetic profile of 131I-labeled MAb 16.88 was neither influenced by the total protein dose of antibody administered nor affected by specific uptake in tumor tissue in individual patients, as determined on early immunoscintigrams. The larger antibody doses showed a slightly slower excretion of 131I. The assays applied to determine immunogenicity were enzyme-linked immunosorbent assay, radioimmunoassay, and the dot-blot assay. They had sensitivities ranging from 5 ng/mL to 0.5 micrograms/mL for goat or rabbit antihuman IgM. The assays did not reveal antihuman antibody responses.

THE Genito-Urinary Tract Cancer Cooperative Group of the European Organization for Research and Treatment of Cancer (EORTC) has performed a series of phase II studies with strict criteria for the assessment of response in patients with bidimensionally measurable soft tissue or visceral metastases [ 1, 21. Reviewing chemotherapy in urological tumours, Stoter and Williams [3] concluded that methotrexate was not useful in the treatment of prostate cancer. Response to methotrexate in the American National Prostatic Cancer Project (NPCP) protocol 1100 was only 5% [4]. However, the scheduling of methotrexate doses was under investigation in the mid-1980s and in view of activity in other adenocarcinomas (e.g. breast cancer), together with anecdotal reports of activity in prostate cancer, a phase II study of ‘low-dose’ methotrexate (40 mg/m’) given every 2 weeks was started to investigate the effectiveness and toxicity of this schedule in prostate cancer patients. Entry criteria included: positive histology, bidimensionally measurable (clinical, ultrasound, computed tomography) soft tissue or visceral lesions to assess response, age 75 or less, additive hormone therapy to be stopped at least 1 day before the start of therapy, no previous chemotherapy or radiotherapy to the indicator lesion(s), WHO performance status 2 or better, life expectancy greater than 60 days, initial white blood count 3 X 109/1 or greater, initial platelet count 100 X 109/1 or greater, adequate renal function (serum creatinine 120 u,moYl or less, creatinine clearance greater than 75 ml/mm), adequate liver function (bilirubin less than 20 mmol/l), no second tumour, no significant cardiac disease, and no uncontrolled infections. Resnonse was assessed after every two cvcles. WHO criteria for evaluation of response and toxicity were-used [5]. 28 patients with documented progressive hormone-resistant disease entered the study between January 1986 and April 1989. 4 patients were ineligible; 1 had no measurable lesion and 3 had not received previous hormone therapy as required by the protocol. Of the 24 eligible patients (age 46-75 years, median 63.5 years), all had received previous androgen suppressive therapy; in addition 2 had received estramustine phosphate and eight had received radiotherapy to various sites. WHO performance scores were: 0 in 4 patients, 1 in 14, and 2 in 6. 1 natient died before the first assessment after two cvcles (early death from malignant disease). 1 patient died of toxicity after one cycle (early death from toxicity) with nausea and vomiting WHO grade 3, diarrhoea grade 4, oral toxicity grade 4, liver toxicity grade 1, renal toxicity grade 1 and minor haemorrhage. A toxic death was also reported in 1 patient who had a further cycle of therapy after withdrawing because of progression. No complete responses were observed. One patient (5%) had a partial response in inguinal lymph nodes, 10 patients (46%) showed no change and 11 patients (50%) had progressive disease. Full doses of drug were given with all cycles of treatment. Leucovorin rescue was only given if toxicity was encountered. The median number of courses was two (mean 3.5, range l-10). The dose was delayed (3-7 days) on three occasions. Haematological toxicity was tolerable. The lowest white cell count was 3.2 x 109/1 (range 3.2-9.7 x 109/1, median 4.5 x 109). The lowest platelet count was 17 x 109/1 (range 17-530 X 109/1, median 174 X 109). Methotrexate at a dose of 40 mg/m2 given every 2 weeks (with

Summary Monoclonal antibodies (MoAbs) with specificity to tumour-associated antigens have become increasingly available during the past years. Presently, they are being applied in various in vitro diagnostic assays. They have contributed to the knowledge of cancer biology to a large extent. The understanding of cell surface characteristics and antigenic phenotype of tumours has in particular influenced the approach in the treatment of leukemias and lymphomas. From successful tumour localization in patients by gamma-emitting radiolabelled MoAbs it became clear, that these proteins offer a unique possibility to target therapeutic agents to tumour sites. The mere administration of MoAbs did not result in sufficient clinical benefit, but with proper precautions high doses of murine antibody were well tolerated. In order to use MoAbs as a carrier system, various toxins, cytostatic drugs, or radionuclides have been conjugated to these proteins. Thus far, specific problems were encountered not only associated with the immunoconjugate itself, but also to its fate in the patient. With regard to the substantial knowledge on the use of MoAbs in vivo obtained from animal tumour models, immunoscintigraphy in patients, and phase I serotherapy trials, we will undoubtedly determine the optimal conditions required for a conjugated anti-tumour agent to achieve enhanced cytotoxicity without increased side-effects. Preliminary results with high doses of 131 I-labelled MoAbs in patients having tumour lesions expressing relevant antigens encourage further studies with immunoconjugutes, in cancer treatment. While much work needs to be done to further define the role of MoAbs as a new treatment modality in malignancies, this area of immunotherapy deserves great emphasis for the development of effective conjugates for future patients.