Phase I and pharmacological trial of lapatinib in combination with gemcitabine in patients with advanced breast cancer.

BACKGROUND: Lapatinib has proven efficacy as monotherapy and in combination with capecitabine in patients with metastatic breast cancer (MBC) overexpressing HER2 and/or EGFR. Gemcitabine also has anti-tumor activity in MBC and a favourable toxicity profile. In this phase I study lapatinib and gemcitabine were combined. METHODS: Female patients with advanced BC were given lapatinib once daily (QD) in 28-day cycles with gemcitabine administered on day 1, 8 and 15. Physical examinations, vital signs and blood sampling for hematology, clinical chemistry and pharmacokinetics (PK) and radiological assessments of disease were performed at regular intervals. RESULTS: In total, 33 patients were included. Six dose-limiting toxicities were observed, mostly grade 3 increases in liver function tests. Most common toxicities were fatigue (73%), nausea (70%), diarrhea (58%), increases in ALAT and ASAT (55 and 52%, respectively) and rash (46%). The maximum tolerated dose was lapatinib 1250 mg QD with gemcitabine 1000 mg/m(2). Lapatinib and gemcitabine PK did not appear to be influenced by each other. Anti-tumor activity was observed with one patient (4%) showing complete response and six (23%) partial response. CONCLUSION: Despite a slightly increased toxicity profile compared to their respective monotherapies, lapatinib and gemcitabine can be safely combined while showing signs of anti-tumor activity.

A randomized phase II study investigating the addition of the specific COX-2 inhibitor celecoxib to docetaxel plus carboplatin as first-line chemotherapy for stage IC to IV epithelial ovarian cancer, Fallopian tube or primary peritoneal carcinomas: the DoCaCel study.

BACKGROUND: In ovarian cancer, cyclooxygenase-2 (COX-2) overexpression is prognostic for poor survival. We investigated the efficacy of celecoxib (C), a selective COX-2 inhibitor, added to docetaxel (Taxotere)/carboplatin (DC) in advanced ovarian cancer. PATIENTS AND METHODS: In a phase II, randomized study, 400 mg celecoxib b.i.d. was added to first-line DC treatment (DCC). Celecoxib was to be continued after DC termination up to 3 years. Study end points were tolerability, progression-free survival (PFS) and overall survival (OS). RESULTS: 151 of 196 eligible patients were diagnosed with stage IIIC/IV disease. Median follow-up for patients alive was 32.3 months. Celecoxib was used during a mean of 8.5 months. Twenty-three of 97 DCC patients stopped celecoxib prematurely, mainly due to skin reactions. Complete biochemical response was achieved in 51/78 DC patients (65%) versus 57/78 DCC patients (75%, not significant). In both study arms, median PFS was 14.3 months and median OS 34 months. COX-2 was expressed in 82% of 120 tumor samples retrospectively recovered. The PFS and OS of patients with intermediate/high COX-2 expression were similar to that in the other patients. CONCLUSION: Celecoxib did not influence PFS and OS, but interpretation of results is hampered by premature celecoxib discontinuation.

Lapatinib: clinical benefit in patients with HER 2-positive advanced breast cancer.

BACKGROUND: Lapatinib, a tyrosine kinase inhibitor of human epidermal growth factor receptor 2 (HER2), has shown activity in combination with capecitabine in patients with HER2-positive advanced breast cancer progressive on standard treatment regimens. We present results on preapproval drug access for this combination in such patients occurring in the general oncology practice in the Netherlands. METHODS: Patients with HER2-positive advanced breast cancer progressive on schedules containing anthracyclines, taxanes, and trastuzumab were eligible. Brain metastases were allowed if stable. Lapatinib 1250 mg÷day was given continuously in combination with capecitabine 1000 mg÷m2 twice daily for two weeks in a three-week cycle. Efficacy was assessed by use of response evaluation criteria in solid tumours version 1.0. Progression-free survival (PFS) and overall survival (OS) were calculated. RESULTS: Eighty-three patients were enrolled from January 2007 until July 2008. The combination was generally well tolerated and the most common drug-related serious adverse events were nausea and÷or vomiting (5%) and diarrhoea (2%). Seventy-eight patients were evaluable for response. Clinical benefit (response or stable disease for at least 12 weeks) was observed in 50 patients (64%) of whom 15 had a partial response and 35 stable disease. The median PFS and OS were 17 weeks (95% CI: 13 to 21) and 39 weeks (95% CI: 24 to 54), respectively. For OS, higher Eastern Cooperative Oncology Group (ECOG) status (p=0.016), brain metastases at study entry (p=0.010) and higher number of metastatic sites (p=0.012) were significantly negative predictive factors. CONCLUSION: In a patient population with heavily pretreated HER2-positive advanced breast cancer lapatinib plus capecitabine was well tolerated and offered clinical benefit.

Factors influencing catheter-related infections in the Dutch multicenter study on high-dose chemotherapy followed by peripheral SCT in high-risk breast cancer patients.

Neutropenia following high-dose chemotherapy leads to a high incidence of infectious complications, of which central venous catheter-related infections predominate. Catheter-related infections and associated risk factors in 392 patients participating in a randomized adjuvant breast cancer trial and assigned to receive high-dose chemotherapy and peripheral stem-cell reinfusion were evaluated. Median catheter dwell time was 25 days (range 1-141). Catheter-related infections were seen in 28.3% of patients (11 infections per 1000 catheter-days). Coagulase-negative staphylococci were found in 104 of 186 positive blood cultures (56%). No systemic fungal infections occurred. Cox regression analysis showed that duration of neutropenia >10 days (P=0.04), using the catheter for both stem-cell apheresis and high-dose chemotherapy (P= <0.01), and use of total parenteral nutrition (TPN, P=0.04) were predictive for catheter-related infections. In conclusion, a high incidence of catheter-related infections after high-dose chemotherapy was seen related to duration of neutropenia, use of the catheter for both stem-cell apheresis and high-dose chemotherapy, and use of TPN. Selective use and choice of catheters could lead to a substantial reduction of catheter-related infectious complications.

High-vs low-dose cytarabine combined with interferon alfa in patients with first chronic phase chronic myeloid leukemia. A prospective randomized phase III study.

A prospective randomized phase III study was performed to evaluate whether intensified cytarabine would induce a higher response rate and longer event-free interval as compared to low-dose cytarabine in chronic myeloid leukemia (CML). One hundred and eighteen patients with CML in early chronic phase entered the study. Twenty-eight out of 32 patients assigned to group A received two cycles of a combination of intensified cytarabine and idarubicin followed by interferon alfa (IFN-alpha) maintenance, 28 patients in group B received standard treatment by a combination of low-dose cytarabine and IFN-alpha. Forty-nine patients with a human leukocyte antigen-identical sibling donor proceeded to allogeneic stem cell transplantation (allo-SCT) and nine patients were excluded from the analysis. Hematological response was observed in 97% of the patients in group A vs 86% of the patients in group B during the first year of treatment. In group A, 16 patients (50%) achieved a major cytogenetic response, which compared to seven patients (25%) with a major cytogenetic response in group B. With a median follow-up of 58 months (range 34-76), event-free survival was not significantly different between arms A and B. The estimated 5-year survival rate was 56% in the intensified arm and 77% in the low-dose arm (P = 0.05). Recipients of allo-SCT showed a 5-year estimated survival rate of 55%. Although intensified cytarabine induced a higher initial percentage of major and complete cytogenetic responses, responses were not sustained by IFN-alpha maintenance therapy.

Molecular subtypes of breast cancer and amplification of topoisomerase II alpha: predictive role in dose intensive adjuvant chemotherapy.

Benefit from chemotherapy treatment in breast cancer patients is determined by the molecular make-up of the tumour. In a retrospective analysis, we determined the molecular subtypes of breast cancer originally defined by expression microarrays by immunohistochemistry in tumours of patients who took part in a randomised study of adjuvant high-dose chemotherapy in breast cancer. In addition, the topoisomerase II alpha (TOP2A) amplification status was determined by fluorescence in situ hybridisation and chromogenic in situ hybridisation. 411 of the 753 tumours (55%) were classified as luminal-like, 137 (18%) as basal-like and 205 (27%) as human epithelial receptor type 2 (HER2) amplified. The basal-like tumours were defined as having no expression of ER and HER2; 98 of them did express epidermal growth factor receptor and/or cytokeratin 5/6. The luminal-like tumours had a significantly better recurrence free and overall survival than the other two groups. From the 194 HER2-positive tumours, 47 (24%) were shown to harbour an amplification of TOP2A. Patients with an HER2-amplified tumour randomised to the high-dose therapy arm did worse than those in the conventional treatment arm, possibly caused by the lower cumulative anthracycline dose in the high-dose arm. The tumours with a TOP2A amplification contributed hardly to this difference, suggesting that TOP2A amplification is not the cause of the steep dose-response curve for anthracyclines in breast cancer. Possibly, the difference of the cumulative dose of only 25% between the treatment arms was insufficient to yield a survival difference.

Capecitabine, epirubicin and cisplatin in the treatment of oesophagogastric adenocarcinoma.

BACKGROUND: Inoperable or metastatic oesophagogastric adenocarcinoma has a poor prognosis. From the many different chemotherapeutic regimens used in the past, a combination of epirubicin, cisplatin and continuous 5-fluorouracil infusion (ECF) showed a consistent response rate of +/- 50% with acceptable toxicity. Continuous 5-FU infusion may be replaced by oral fluoropyrimidines. Here we evaluate treatment with epirubicin and cisplatin combined with oral capecitabine (ECC), replacing intravenous 5-FU infusion. METHODS: Retrospectively, we analysed 23 consecutive patients who were treated with epirubicin, cisplatin and oral capecitabine for inoperable or metastatic oesophagogastric adenocarcinoma during 2002 and 2003. RESULTS: The overall response rate was 57%; another 26% achieved stable disease and only 17% had progressive disease. The median duration of response was 6.4 months; the median survival was 9.0 months. Previously treated patients (n=10) had a significantly worse overall response rate (20%) compared with previously untreated patients (85%). A nonsignificant difference in median survival was found between these groups (3.9 vs 9.8 months in previously treated vs untreated patients). An acceptable incidence of grade 3 and 4 toxicity was found. CONCLUSION: Capecitabine in combination with epirubicin and cisplatin is an effective and safe alternative to ECF, without the risks of a continuous venous access.

Efficacy of high-dose alkylating chemotherapy in HER2/neu-negative breast cancer.

BACKGROUND: High-dose chemotherapy in the adjuvant treatment of breast cancer has been abandoned by many. PATIENTS AND METHODS: 885 patients with stage III primary breast cancer and four or more axillary lymph node metastases were randomised to receive either five courses of FEC (fluorouracil, epirubicin and cyclophosphamide) followed by radiation therapy and tamoxifen, or the same treatment but with high-dose alkylating chemotherapy (cyclophosphamide, thiotepa and carboplatin) replacing the fifth course of FEC. Of these patients, 621 had HER2/neu-negative disease, as determined by immunohistochemistry and chromogenic in situ hybridisation. RESULTS: At a median follow-up of 84 months, a trend for a better relapse-free survival was observed in the high-dose arm: (hazard ratio (HR) 0.84, P = 0.076, two-sided). The 621 patients with HER2/neu-negative disease benefited from high-dose therapy, while patients with HER2/neu-positive disease did not (test for interaction, P = 0.006). There was a marked relapse-free survival benefit for patients with HER2/neu-negative disease (71.5% versus 59.1%, 5 years after randomisation; HR 0.68, P = 0.002) and also a survival benefit (78.2% versus 71.0% at 5 years; HR 0.72, P = 0.02). CONCLUSIONS: The findings from this subgroup analysis provide additional evidence that HER2/neu-positive breast cancer is relatively resistant to alkylating agents. For HER2/neu-negative tumours, however, high-dose chemotherapy should remain the subject of clinical studies.

Generation of B-cell chronic lymphocytic leukemia (B-CLL)-reactive T-cell lines and clones from HLA class I-matched donors using modified B-CLL cells as stimulators: implications for adoptive immunotherapy.

Allogeneic stem cell transplantation following reduced-intensity conditioning is being evaluated in patients with advanced B-cell chronic lymphocytic leukemia (B-CLL). The curative potential of this procedure is mediated by donor-derived alloreactive T cells, resulting in a graft-versus-leukemia effect. However, B-CLL may escape T-cell-mediated immune reactivity since these cells lack expression of costimulatory molecules. We examined the most optimal method to transform B-CLL cells into efficient antigen-presenting cells (APC) using activating cytokines, by triggering toll-like receptors (TLRs) using microbial pathogens and by CD40 stimulation with CD40L-transfected fibroblasts. CD40 activation in the presence of IL-4 induced strongest upregulation of costimulatory and adhesion molecules on B-CLL cells and induced the production of high amounts of IL-12 by the leukemic cells. In contrast to primary B-CLL cells as stimulator cells, these malignant APCs were capable of inducing the generation of B-CLL-reactive CD8(+) CTL lines and clones from HLA class I-matched donors. These CTL lines and clones recognized and killed primary B-CLL as well as patient-derived lymphoblasts, but not donor cells. These results show the feasibility of ex vivo generation of B-CLL-reactive CD8(+) CTLs. This opens new perspectives for adoptive immunotherapy, following allogeneic stem cell transplantation in patients with advanced B-CLL.

[Pregnancy and chemotherapy; an apparent contradiction]. / Zwangerschap en chemotherapie; een schijnbare tegenstelling.

Two women aged 34 and 32, were diagnosed with cancer during pregnancy. The 34-year-old woman with breast cancer diagnosed during the first trimester of pregnancy, had just undergone breast-conserving surgery. She chose to have an abortion before adjuvant chemotherapy was started. A year after chemotherapy ended she became pregnant again and gave birth to a healthy child. After 3 years there were no signs of metastases. In the 32-year-old woman with a malignant lymphoma diagnosed during the third trimester of pregnancy, chemotherapy had to be started because she developed V. cava superior syndrome. The dyspnoea disappeared and a week after the first treatment she gave birth to a healthy child. A year after completion of treatment she was in complete remission and her child was developing well. Pregnancy is not always a contraindication for starting chemotherapy. However, in order to reduce the risk to mother and child as much as possible, the duration of the pregnancy as well as different groups of cytostatic drugs have to be taken into consideration. A multidisciplinary approach to mother and child is essential.

A phase II trial of ZD0473 in platinum-pretreated ovarian cancer.

The primary aim of this phase II trial was to assess the antitumour activity of ZD0473 in ovarian cancer patients who had failed initial platinum-based therapy. Patients (n=94) were classified as either platinum-sensitive (n=35) or platinum-resistant (n=59) depending on whether they had relapsed or progressed within 26 weeks of completing first-line platinum-based chemotherapy. Patients initially received 120 mg/m(2) ZD0473 as a 1-h intravenous (i.v.) infusion on day 1 of a 3-week cycle. If well tolerated, the dose could be escalated to 150 mg/m(2). Few patients (9%) withdrew because of treatment-related adverse events and no clinically significant oto-, nephro- or neurotoxicity was observed. Objective response rates for platinum-resistant and sensitive patients were 8.3 and 32.4%, respectively, and clinical benefit was observed in 76.5% of the sensitive patients. Median time to progression was 57 and 180 days, and median time to death was 242 and 402 days, for resistant and sensitive patients, respectively. In conclusion, ZD0473 has a manageable toxicity profile and encouraging activity in platinum-sensitive ovarian cancer patients.

Results of ZD0473 in platinum-pretreated ovarian cancer: analysis according to platinum free interval.

Resistance to platinum-containing regimens can develop in many women with ovarian cancer and may lead to relapse in > 80% of patients. ZD0473 is a new-generation platinum agent that, in preclinical studies, shows evidence of antitumour activity and overcomes platinum-resistance mechanisms. This Phase II trial has evaluated the efficacy and tolerability of ZD0473 in second-line ovarian cancer patients. Patients received ZD0473 120 mg/m2 (1-h iv infusion, day 1 q 3-weeks); the starting dose was increased to 150 mg/m2 after a safety review. We report here on results when patients are divided into four cohorts depending upon whether they were considered platinum-resistant or -sensitive. Patients were placed into one of 3 cohorts if they were platinum resistant (relapsed/progressed < or = 26 weeks after completion of prior platinum-based chemotherapy) or cohort 4 if this period was > 26 weeks (sensitive). Ninety-four patients were recruited to the trial (59 resistant, 35 sensitive; median age 58 [range 27-75] years; 86 with performance status [PS] < or = 1). Forty-nine patients received a starting dose of 120 mg/m2, of which 15 escalated to 150 mg/m2, and 45 received a starting dose of 150 mg/m2. Overall, the median number of treatment cycles received was 3 (range 1-8). Grade 3/4 thrombocytopenia was the most common haematological adverse event occurring in 62% of patients overall. Grade 3/4 lethargy, vomiting and nausea were the most common non-haematological toxicities. No clinically significant oto-, nephro- or neurotoxicity was observed. Overall response rates for all platinum-resistant and -sensitive patients were 8.3% and 32.4%, respectively. Stable disease occurred in 17 resistant and 15 sensitive patients.

Complete remission of accelerated phase chronic myeloid leukemia by treatment with leukemia-reactive cytotoxic T lymphocytes.

Relapse of chronic myeloid leukemia (CML) in chronic phase after allogeneic stem cell transplantation (SCT) can be successfully treated by donor lymphocyte infusion (DLI). However, relapse of accelerated phase CML, blast crisis, or acute leukemia after allogeneic SCT are resistant to DLI in the majority of cases. In vitro-selected and expanded leukemia-reactive T-cell lines may be more effective in inducing an antileukemic response in vivo. To treat a patient with accelerated phase CML after allogeneic SCT, leukemia-reactive cytotoxic T-lymphocyte (CTL) lines were generated from her HLA-identical donor. Using a modification of a limiting dilution assay, T cells were isolated from the donor, selected based on their ability to inhibit the in vitro growth of CML progenitor cells, and subsequently expanded in vitro to generate CTL lines. Three CTL lines were generated that lysed the leukemic cells from the patient and inhibited the growth of leukemic progenitor cells. The CTL did not react with lymphocytes from donor or recipient and did not affect donor hematopoietic progenitor cells. The 3 leukemia-reactive CTL lines were infused at 5-week intervals at a cumulative dose of 3.2 x 10(9) CTL. Shortly after the third infusion, complete eradication of the leukemic cells was observed, as shown by cytogenetic analysis, fluorescence in situ hybridization, molecular analysis of BCR/ABL-mRNA, and chimerism studies. These results show that in vitro cultured leukemia-reactive CTL lines selected on their ability to inhibit the proliferation of leukemic progenitor cells in vitro can be successfully applied to treat accelerated phase CML after allogeneic SCT.

T cells recognizing leukemic CD34(+) progenitor cells mediate the antileukemic effect of donor lymphocyte infusions for relapsed chronic myeloid leukemia after allogeneic stem cell transplantation.

Adoptive immunotherapy with donor lymphocyte infusions (DLI) is an effective treatment for relapsed chronic myeloid leukemia (CML) after allogeneic stem cell transplantation. To identify the effector and target cell populations responsible for the elimination of the leukemic cells in vivo we developed an assay to measure the frequency of T lymphocyte precursor cells capable of suppressing leukemic progenitor cells. Target cells in this assay were CML cells that were cultured in the presence of stem cell factor, interleukin 3, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, and erythropoietin. [3H]thymidine incorporation at day 7 represented the proliferation of the progeny of the CD34(+) CML progenitor cells, and not of the more mature CD34(-) CML cells. Effector cells were mononuclear cells, which were used in a limiting dilution analysis to measure the frequencies of CML progenitor cell-inhibitory lymphocyte precursors (PCILp) in peripheral blood of seven patients before and after DLI for relapsed CML. In the six patients who entered complete remission, a 5- to 100-fold increase of PCILp was found during the clinical response. In the patient with resistant relapse the frequency of PCILp was <10 per ml before and after DLI. Leukemia-reactive helper T lymphocyte precursor frequencies remained unchanged after DLI. A significant increase in cytotoxic T lymphocyte precursor frequency against more mature leukemic cells was found in only two responding patients. These results indicate that T cells specifically directed against CD34(+) CML progenitor cells mediate the antileukemic effect of DLI.

Generation of leukemia-reactive cytotoxic T lymphocytes from HLA-identical donors of patients with chronic myeloid leukemia using modifications of a limiting dilution assay.

Donor leukocyte transfusions (DLT) have an anti-leukemic effect in most patients with a relapse of chronic myeloid leukemia (CML) after allogeneic stem cell transplantation. However, DLT are often complicated by graft-versus-host disease. Selection of donor lymphocytes with a relative specificity for leukemic cells is desirable. The generation of leukemia-reactive cytotoxic T lymphocyte (CTL) responses between HLA-identical donors and patients in bulk cultures showed major variations, and false negative results were observed. In a modification of a limiting dilution analysis (LDA) two-fold serial dilutions of HLA-identical donor mononuclear cells (MNC) were cultured in the presence of CML cells. The anti-leukemic CTL precursor frequencies in these donors varied between <1 and 9 per 106 MNC. HLA-restricted CD4+ or CD8+ lymphocytes as well as MHC non-restricted gammadelta T cells were responsible for the anti-leukemic responses. A positive correlation between cytotoxicity in the various wells after 3, 4 and 5 weeks of culture could be found. The LDA may be superior to bulk cultures in selecting stable immune responses and in separating multiple different anti-leukemic T cell responses in each donor-patient combination.

Excision of a haemophilic pseudotumour of the ilium, complicated by fistulation.

We report the case of a patient with a haemophilic pseudotumour of the ilium who developed chronic fistulation, 6 months after en-bloc resection. During the initial resection, the large defect in the iliac wing was filled with bone cement, which may have contributed to fistula formation. A second surgical procedure consisted of excision of the fistula and bone cement and the dead space was obliterated by bringing the gluteus medius muscle into the defect. The fistula recurred, however. Reexcision of the fistula and obliteration of the dead space by a pedicled rectus abdominis muscle flap resulted in eradication of the fistula. We emphasize the importance of obliteration of dead space, resulting from large pseudotumour resection. The use of bone cement is not advocated. If a fistula does occur, a pedicled rectus abdominis muscle flap may be considered.

Cytotoxic T-lymphocyte (CTL) responses against acute or chronic myeloid leukemia.

In addition to chemotherapy and irradiation, in the context of allogeneic stem cell transplantation (SCT), the donor cell-mediated antileukemic effect can lead to sustained complete remissions, also in cases of a large tumor load. This phenomenon appears to be an immunologically mediated response, possibly due to various effector cell populations. Cytotoxic T-lymphocyte (CTL) responses against minor histocompatibility antigens with restricted tissue distribution, in particular restricted to some or all hematopoietic cells, may be highly efficient in inducing anti-leukemic responses for adoptive immunotherapy. Specific CTL responses against leukemia-associated antigens may be generated using leukemic cells modified to coexpress costimulatory molecules identical to professional antigen-presenting cells. Donor-derived T cells recognizing such antigens may be used in the context of allogeneic SCT to induce complete and sustained remissions, also in patients with leukemia refractory to chemotherapy. In these circumstances, the primary objective of allogeneic SCT may be not to diminish the number of malignant cells by the chemotherapy and irradiation as part of the conditioning regimen, but to allow immunotherapy against leukemic cells using donor lymphocyte populations.

Generation of dendritic cells expressing bcr-abl from CD34-positive chronic myeloid leukemia precursor cells.

Patients with a relapse of chronic myeloid leukemia (CML) after allogeneic bone marrow transplantation can be successfully treated with blood mononuclear cells from the original bone marrow donor. However, the antileukemic effect of this treatment is often accompanied by graft-versus-host disease (GVHD). Treatment with cytotoxic T-lymphocyte (CTL) lines or clones that are specifically generated against leukemic antigen-presenting cells from the patient, may separate antileukemic effects from GVHD. In this report we demonstrate that after culturing CD34-positive cells purified from bone marrow of patients with chronic phase CML in medium containing human serum, GM-CSF, TNF alpha, and IL-4 up to 28% of the cultured cells were dendritic cells, characterized by morphology, phenotypic analysis, and their efficient capacity to stimulate allogeneic T lymphocytes. The expression of HLA and costimulatory molecules and the stimulatory capacity of the dendritic cell-enriched cell suspensions were optimal between days 7 and 10 after onset of the cultures. Fluorescence in situ hybridization revealed that all cultured dendritic cells contained the CML specific t(9;22) translocation. PCR analysis showed expression of the translocation specific bcr-abl mRNA. These leukemic dendritic cells may enhance the induction and proliferation of CTL lines and clones with more specificity for the leukemic cells.

Interleukin-10, interleukin-12, and tumor necrosis factor-alpha differentially influence the proliferation of human CD8+ and CD4+ T-cell clones.

Activation and proliferation of human T lymphocytes in vitro can be obtained by various stimuli including specific antigens, mitogens, and cytokines. Here we describe the effect of interleukin-10, interleukin-12 and tumor necrosis factor-alpha on the interleukin-2 dependent proliferation and function of established human CD4+ and CD8+ alloreactive T-cell clones in the absence of antigen presenting cells. IL-12 and TNF-alpha both demonstrated an inhibitory effect on the proliferation of CD8+ cytotoxic T lymphocyte clones, whereas IL-10 enhanced the proliferation. IL-12-induced inhibition of CD8+ CTL clones was not mediated by the endogenous production of TNF-alpha by these clones. The strong inhibitory effect of IL-12 and TNF-alpha did not result in apoptosis. These cytokines did not alter the cytotoxicity of CD8+ CTL clones. When CD4+ T-cell clones were tested in the absence of APC, no significant change in IL-2-dependent proliferation due to IL-10, IL-12, and TNF-alpha could be measured. Since these effects on established CTL clones are in contrast to the effects of IL-10, IL-12, and TNF-alpha during the induction phase of immune responses, a dichotomy of immunomodulatory cytokines such as IL-10, IL-12, and TNF-alpha early and late in the immune response is suggested.