Interleukin-12 inhibits apoptosis in chronic lymphatic leukemia (CLL) B cells.

The purpose of the present study was to investigate the effect of interleukin-12 on apoptosis of chronic lymphatic leukemia (CLL) B cells. Apoptotic indices were determined in highly purified CD5(+) B lymphocytes isolated from peripheral blood of seven patients with histologically confirmed CLL. Interleukin-4 as a known inhibitor of apoptosis was used as control. Quantitative analysis of apoptosis was determined by cell death detection ELISA. Our findings indicate that interleukin-12 inhibits ex vivo apoptosis in a large proportion of B-CLL patients and may be closely involved in the pathogenesis of disease. Therefore, our results may help identify potential new therapeutic targets in this malignancy.

Primary apoptosis as a prognostic index for the classification of metastatic renal cell carcinoma.

PURPOSE: We identified novel biological markers of prognosis in primary histopathological specimens from patients with metastatic renal cell carcinoma. MATERIALS AND METHODS: Apoptotic indexes (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling), proliferation rates (Ki-67 antigen), p21 (WAF1/cip1) expression and CD95 (APO-1/Fas) expression were determined in paraffin embedded nephrectomy specimens from 73 patients with histologically confirmed, progressive metastatic disease. Kaplan-Meier survival analysis, log rank statistics and 2-proportional Cox regression analysis were done to identify new risk factors in addition to conventional classification criteria, and demonstrate statistical independence. RESULTS: Multivariate analysis indicated that primary tumor apoptosis (p = 0.0116) and the interval from diagnosis to metastatic disease (p = 0.002) had a high predictive impact on overall survival after initial diagnosis. Patients were assigned to 2 risk groups, namely a poor prognosis group with a median survival of 20 months, defined by apoptosis less than 6% in the primary tumor nephrectomy specimen and a time from initial diagnosis to metastatic disease of less than 6 months, and a good prognosis group with a median survival of 56 months, defined as the absence of 1 or 2 risk factors. CONCLUSIONS: Our findings showed that primary tumor apoptosis is a novel independent predictor in patients with metastatic renal cell carcinoma at initial diagnosis. It leads to a new prognostic index in the pretreatment classification of metastatic renal cell carcinoma.

Interferon-alpha resistance in renal carcinoma cells is associated with defective induction of signal transducer and activator of transcription 1 which can be restored by a supernatant of phorbol 12-myristate 13-acetate stimulated peripheral blood mononuclear cells.

Therapy of selected human malignancies with interferon-alpha is widely accepted but often complicated by the emergence of interferon-alpha resistance. Interferon is a pleiotropic cytokine with antiproliferative, antitumour, antiviral and immunmodulatory effect; it signals through the Jak-STAT signal transduction pathway where signal transducer and activator of transcription 1 plays an important role. Here we report both, a lack of signal transducer and activator of transcription induction in interferon-alpha resistant renal cell carcinoma cells and signal transducer and activator of transcription 1 reinduction of phorbol 12-myristate 13-acetate-stimulated peripheral blood mononuclear cells supernatant. Preliminary experiments on the identification of the molecules that reinducing signal transducers and activators of transcription 1 indicate that interferon-gamma may be the responsible candidate cytokine, but several others may be involved as well. This work provides the basis for therapeutic strategies directed at the molecular modulation of interferon-alpha resistance in human neoplasms.

13cis- and all-trans retinoic acid have antiproliferative effects on CML cells and render IFN alpha antiproliferative potency after combined treatment in vitro.

The treatment of CML with IFN alpha is limited due to resistance against this substance. Recent studies with different cells than chronic myelogenous leukemic cells revealed a synergistic effect of a combined use of Retinoids (RA) and IFN alpha. The purpose of the study was to detect possible interactions of IFN alpha and RA in CML considering also the effect of the BCR-ABL gene-product. Therefore, we investigated three CML cell lines in their proliferation after incubation with IFN alpha and Retinoids alone and in combination. We measured low susceptibility to IFN alpha but a marked influence of the Retinoids. In combination, the growth inhibition was enhanced potentially in response to an increased efficacy of IFN alpha. Even solely, ineffective concentrations of both substances lead to decreased proliferation.

Interleukin 10 (IL-10): an immunosuppressive factor and independent predictor in patients with metastatic renal cell carcinoma.

Interleukin 10 (IL-10) is an immunosuppressive factor and has been detected in tumour cell cultures of renal cell carcinoma and of malignant melanoma. IL-10 has been described as a cytokine of the Th2 response; it is able to suppress antigen-presenting cells (APCs) and may lead to down-regulation of HLA class I and II molecules on dendritic cells and to anergy of T-lymphocytes. We evaluated pretreatment serum levels of soluble IL-10 and various clinical parameters to determine their prognostic value in 80 advanced renal cell carcinoma patients seen at our institution between May 1990 and April 1996. For statistical evaluation we used both univariate and multivariate Cox proportional hazards models. An elevated pretreatment serum level of IL-10 was a statistically independent predictor of unfavourable outcome (P < 0.0028), in addition to the well-known clinical and biochemical risk factors. These data support risk stratification for future therapeutic trials and identify a predictor which needs to be validated in prospective studies and may potentially influence decision making in palliative management of patients with metastatic renal cell carcinoma. These data also suggest a potential role of IL-10 in the development of advanced renal cell carcinoma and in the future design of therapeutic strategies.

Clinical and in vitro response to 13-cis-retinoic acid in interferon-alpha resistant renal cell carcinoma.

Retinoids are known to control many important biological processes, including differentiation, morphogenesis, growth and tissue homeostasis. More recently, clinical and pre-clinical results provide evidence for an antiproliferative effect of 13-cis-retinoic acid (13cRA) in interferon-alpha (IFN-alpha) treated renal cell carcinoma patients. The manner in which 13cRA augments antitumor effects and modulates biologic and clinical responses of renal cell carcinoma to IFN-alpha remains elusive. In the present study, we report induction of apoptosis and objective tumor regression in response to 13cRA in advanced renal cell carcinoma patients refractory to IFN-alpha. Among 21 patients treated there were one complete and four partial remissions (objective response rate, 24%; median response duration 8+ months). Preliminary evidence suggests that 13cRA acid may reverse IFN-alpha resistance in renal cell carcinoma.

Peripheral blood tyrosinase messenger RNA detection and survival in malignant melanoma.

BACKGROUND: The most widely accepted criteria for the evaluation of prognosis of malignant melanoma are histopathologic and clinical presentation. No currently available laboratory tests provide additional prognostic information. It has recently been suggested that reverse transcription and polymerase chain reaction (RT-PCR)-based detection of tyrosinase messenger RNA (mRNA) in peripheral blood might be useful in the early detection of circulating tumor cells, since tyrosinase is thought to be a melanocyte-specific marker. PURPOSE: To further evaluate the clinical relevance of this potential marker, we examined peripheral blood samples from patients with malignant melanoma in different stages of disease for the presence of tyrosinase mRNA. METHODS: Total cellular RNA was extracted from heparinized peripheral blood cells from 64 patients with malignant melanoma, from five healthy control subjects, and from four patients with other cancers using the RNAzol A method. For analysis of tyrosinase mRNA, RT-PCR was performed as previously described by Smith et al.; the sensitivity of this assay was tested using RNA extracted from human melanoma cells (SK-mel 1 and SK-mel 3 cell lines) serially diluted with peripheral blood obtained from healthy control subjects. Two additional human melanoma cell lines (SK-mel 30 and RPMI-7951) served as positive controls for RT-PCR detection of tyrosinase mRNA. Overall patient survival curves were constructed using Kaplan-Meier estimates. RESULTS: Tyrosinase mRNA was detected by RT-PCR assay of all four of the established melanoma cell lines tested. Nine of the 64 patients with malignant melanoma were found to have detectable tyrosinase mRNA in their peripheral blood cells (tyrosinase-positive patients). The 16 patients with localized primary melanoma did not have detectable tyrosinase mRNA in their peripheral blood cells. Among the 48 patients with metastatic disease, all 27 patients who exhibited no evidence of disease progression were tyrosinase negative. Notably, all nine tyrosinase-positive patients had visceral metastases and were found to exhibit disease progression at the time of the sampling. Four of the nine tyrosinase-positive patients were also found to test negative at times without evidence of progressive disease; one patient became negative after achieving stable disease and three became positive for tyrosinase transcripts on disease progression. The probability of survival from time of sampling was significantly lower in the nine tyrosinase-positive patients when tested versus the 23 patients with comparable disease but without detectable tyrosinase mRNA (two-sided; P < or = .05). CONCLUSIONS: The results of this study demonstrate that the detection of tyrosinase mRNA in cells in the peripheral blood by RT-PCR may be a useful prognostic marker for predicting tumor progression and poor clinical outcome in patients with malignant melanoma.

Platelet endothelial cell adhesion molecule-1 (PECAM-1): a potential prognostic marker involved in leukocyte infiltration of renal cell carcinoma.

We investigated immunohistochemically the leukocyte infiltrate [CD3, CD4, CD8, CD11a, CD11b, CD14, CD56, VLA-4 and platelet endothelial cell adhesion molecule-1 (PECAM-1)] and the endothelial expression of cell adhesion molecules (PECAM-1, VCAM-1, ICAM-1 and ICAM-2) in 23 renal cell carcinoma tumor tissues. Tumors with a moderate or high density of PECAM-1 positive endothelia showed a stronger infiltration with PECAM-1-positive leukocytes as compared to tumors with a low density of positive endothelia (p<0.0085). Additionally, overall survival of patients who presented with tumors exhibiting a moderate or high density of PECAM-1 endothelia alone or in combination with a PECAM-1-positive infiltrate was extended (median survival: 23.5 months) as compared to patients without these tumor characteristics (median survival: 6.5 months). These results suggest an involvement of PECAM-1 in the process of leukocyte migration and a potential role as a prognostic marker in renal cell carcinoma.

Lymphocyte-conditioned medium in combination with interleukin-2 effectively induces antitumour autoimmunity by adoptive transfer of short activated killer (SHAK) cells.

In this study, effective antitumour immunity was transferred by autologous short activated killer (SHAK) cells induced over four hours with lymphocyte conditioned medium (LCM) and recombinant interleukin-2 (rIL-2). Among eight patients with progressive metastatic renal cell carcinoma refractory to standard therapy, there were six objective tumour responses to SHAKs. Progression-free survival ranged from 0 to 8+ months, and overall survival ranged from 2 to 14+ months, with a median of 9+ months. Systemic toxicity of SHAKs was limited to flulike symptoms. Patient SHAKs provided a tumour-specific immunity, both cellular and humoral (expression and secretion of secondary cytokines, including IL-2, GM-CSF, INF-gamma and TNF-alpha), far superior to rIL-2 activated killer cells.

In vivo tumor necrosis factor-alpha as indicator of biologic and clinical response to low-dose SC recombinant interleukin 2.

The effect of low-dose human recombinant interleukin-2 (rIL-2) on the induction of secondary tumor necrosis factor-alpha (TNF-alpha) in vivo was studied in 16 patients with metastatic renal cell carcinoma. In all patients s.c. rIL-2 resulted in a significant increase in TNF-alpha serum levels within 4 to 8 hours, as determined by enzyme-linked immunosorbent assay (ELISA). TNF-alpha serum concentrations remained elevated up to 24 hours following single s.c. administration of rIL-2. Total secondary TNF-alpha release, as assessed by the area under the curve (AUC), appeared to be independent of dose distribution of rIL-2 (10 million IU rIL-2 q12 hours versus 20 million IU rIL-2 q24 hours). rIL-2 induced TNF-alpha release was significantly higher in patients who had received prior rIL-2 immunotherapy, while steroids resulted in a significant suppression of TNF-alpha release. Secondary TNF-alpha release was statistically associated with progression-free survival of renal cell carcinoma patients and may be a prognostic factor in patients receiving rIL-2.

Immunocytochemical detection of P-glycoprotein: initial expression correlates with survival in renal cell carcinoma patients.

We evaluated 28 patients with advanced renal cell carcinoma for the initial expression of P-glycoprotein (MDR1 gene product) employing immunocytochemistry. Tumor specimens were obtained upon primary tumor nephrectomy. In all patients, progression-free survival time following nephrectomy was evaluated and correlated statistically with the staining results. Progression-free survival of patients with no or very few (< 1%) P-glycoprotein-positive tumor cells (n = 8, median survival 27.0 months) was significantly extended (p < 0.04) as compared to patients with 1% or more P-glycoprotein-positive tumor cells (n = 20, median survival 4.0 months). Correlations with histopathological tumor characteristics were insignificant. These results suggest a potential role for P-glycoprotein as a biologic parameter predictive of tumor progression in renal cell carcinoma patients.

Soluble interleukin 2 receptors abrogate IL-2 induced activation of peripheral mononuclear cells.

Soluble interleukin 2 receptors (sIL-2R) exert a potential role in immunoregulation. We investigated the in vitro effects of sIL-2R on several interleukin 2 (IL-2)-dependent cellular events. Cytotoxicity of human rIL-2-stimulated PBMC against K562 and Daudi was correlated inversely to the concentration of sIL-2R in the culture medium during rIL-2 stimulation. sIL-2R concentrations higher than 4.0 pM produced a significant loss of cytotoxicity (P < 0.01). The effect of different sIL-2R concentrations added to cultured human PBMC on secondary sIL-2R production was tested by ELISA. Secondary sIL-2R production was abrogated by high initial sIL-2R dosages whereas low initial dosages were followed by a continuing production of secondary sIL-2R after five days of culture. Proliferation of the IL-2-dependent mouse cell line CTLL-2-was suppressed by sIL-2R added to the culture medium in a dose-dependent way. The neutralizing capacity of sIL-2R strongly depended on the initial number of CTLL set in per proliferation assay. In contrast, variation of rIL-2-concentration had no significant effect on reduction of proliferation by sIL-2R. Furthermore, preincubation of sIL-2R with rIL-2 did not enhance growth suppression. These last findings indicate that there is at least no functional interaction between sIL-2R and free IL-2, whereas an interaction of sIL-2R with the membrane-bound receptor for IL-2 seems possible.

In vivo time and dose dependency of interleukin-6 secretion in response to low-dose subcutaneous recombinant interleukin-2.

Serum concentrations of Interleukin-6 (IL-6) were determined in renal cell carcinoma patients treated with low-dose subcutaneous human recombinant interleukin-2 (rIL-2). In all patients, administration of rIL-2 resulted in a significant increase in IL-6 serum levels to peak values within 4 to 6 hours as measured by enzyme-linked immunosorbent assays (ELISA). Repetitive administration of rIL-2 induced significantly lower IL-6 serum peaks when compared to the initial administration of rIL-2. Cumulative IL-6 release, as expressed by the area under the concentration curve (AUC), appeared to be independent of rIL-2 dose distribution (10 million IU rIL-2/m2 versus 20 million IU rIL-2/m2), and IL-6 serum peaks showed no direct dose dependency. Prior rIL-2 immunotherapy had no measurable effect on rIL-2 induced IL-6 release, while steroids resulted in a significant suppression of secondary IL-6 did not correlate with response to rIL-2 therapy or survival of rIL-2 treated renal cell carcinoma patients.

Induction of cytokines and cytotoxicity against tumor cells by Newcastle disease virus.

The use of NDV as biological adjuvant in vaccines against human cancer is still actual in several clinical treatment protocols. In this study, we have investigated in vitro-effects of Newcastle disease virus (NDV) strain 73-T on isolated mononuclear blood cells and cultured tumor cells. Cellular cytotoxicity of PBMC freshly isolated from healthy donors against tumor cells was enhanced significantly (p < 0.01) after coincubation of NDV with effector cells. NDV failed to enhance cytotoxicity of effector cells when PBMC were stimulated three days with 500 IU recombinant interleukin-2 (rIL-2) per ml prior to coincubation with the virus. No significant enhancement of cellular lysis was seen when only target cells were coincubated with NDV. As shown by depletion of various lymphocyte subsets, NK cells were the predominant mediator of lysis. Enhancement of cytotoxicity correlated with the induction of interferon-alpha (IFN-alpha) in PBMC by NDV. NDV also induced high amounts of tumor necrosis factor-alpha (TNF-alpha) in PBMC. Induction of interferon-gamma (IFN-gamma) was weak. A direct cytopathic effect (CPE) of NDV on different target cells was detected by colorimetric measurement of metabolic cell activity. The human tumor cell lines A-498, A-704, Caki-1, Caki-2, and K-562 and the fibroblast line MRC-5 showed progressive cellular destruction 48 h after infection with NDV, whereas PBMC and Daudi cells remained unaffected during the observation period. The nontransformed monkey kidney cell line CV-1 and the transformed monkey kidney cell line COS-1 were both lysed by NDV with marginal difference in time course of CPE. Our results indicate a reasonable potential of pleiotropic modifications of the immune response against tumors by NDV.

Low-dose interleukin-2 in combination with interferon-alpha effectively modulates biological response in vivo.

Phenotypic characterization of peripheral blood lymphocytes was performed in patients with advanced metastatic cancer receiving low-dose recombinant interleukin-2 (rIL-2) and recombinant interferon-alpha (rIFN-alpha) as subcutaneous home therapy. A total of 31 patients with progressive metastatic renal cell carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, and Hodgkin's disease, were evaluated. Patients were treated with a combination of low-dose subcutaneous rIL-2 and rIFN-alpha, consisting of a 2-day rIL-2 pulse at 9.0 million IU/m2 twice daily, followed by 6 weeks of combined low-dose rIL-2 at 1.8 million IU/m2 twice daily, 5 days per week, and rIFN-alpha at 5.0 million U/m2 3 times per week. This treatment regimen resulted in an overall significant (p < 0.002) increase in peripheral blood lymphocyte subsets expressing CD3, CD8, CD16, CD25, and CD56. Expansion of peripheral blood natural killer (NK) cells was correlated to treatment response. Thus, treatment-related increase in CD56-positive lymphocytes was 1.8-fold higher in complete or partial responders when compared to progressive disease patients (p = 0.0). Increase in NK cells upon low-dose rIL-2 and rIFN-alpha was associated with a significant expansion (p = 0.0) of peripheral blood eosinophils (r = 0.71). Patient pretreatment using rIL-2, rIL-2 and rIFN-alpha, or chemotherapy abrogated the treatment-induced induction of NK cells and IL-2 receptor- (CD25) positive T lymphocytes, respectively. Peripheral blood NK cells were significantly decreased (p < 0.05) in patients developing neutralizing antibodies specific to rIL-2.

Clinical and preclinical evaluation of recombinant PEG-IL-2 in human.

High dose interleukin-2 alone or in combination with lymphokine activated killer (LAK) cells has demonstrated antitumor activity in a variety of malignant diseases. The currently formulated recombinant human interleukin-2 (IL-2) has limited solubility and short circulatory half life resulting in limited bioavailability. To improve the bioavailability of IL-2 the protein was covalently bound to activated Polyethylenglycol (PEG). We designed a phase I/II trial to evaluate the bioactivity of PEG-IL-2 in man, given as intravenous (iv) bolus injection every two weeks, and to determine safety, efficacy, and the maximum tolerated dose (MTD) in patients with advanced malignancies. Assessment of cytokine levels, phenotypic analyses and differential blood counts were performed to investigate the effects of PEG-IL-2 in-vivo. To compare in-vitro PEG-IL-2 activity to activities of IL-2 we evaluated proliferation, cytotolytic activity, morphology, and phenotype of cytokine activated lymphocytes. Among seven patients treated with PEG-IL-2, there was no objective remission, three patients exhibited stabilisation of disease. Four patients presented with further disease progression. Treatment-related toxicity was mild to moderate (mainly WHO grades I and II) in patients receiving dose levels up to 10 x 10(6) IU/m2 (maximum tolerated single dose in the outpatient setting). No toxic deaths occurred. In comparison to IL-2, the pharmacokinetic profile of PEG-IL-2 exhibited increased plasma levels and a decreased clearance (alpha and beta half-life estimates of 4 and 14 hours, respectively). The analysis of a variety of immunologic parameters demonstrated that PEG-IL-2 has significant biologic activity both in vitro, and in man.

Expansion of peripheral blood natural killer cells correlates with clinical outcome in cancer patients receiving recombinant subcutaneous interleukin-2 and interferon-alpha-2.

Natural killer (NK) cells are believed to contribute to the clinical efficacy of cancer immunotherapy using recombinant interleukin-2 (rIL-2) in humans. In previous trials of high-dose i.v. rIL-2, however, no correlation has been established between circulating NK cells and treatment response. Between January 1989 and October 1990, we treated a total of 47 outpatients with advanced tumors using low-dose s.c. rIL-2 and interferon-alpha-2 (rIFN-alpha). Therapy consisted of a 2-day rIL-2 pulse at 18 million IU/m2/day, followed by 6 weeks of rIL-2 (3.6 x 10(6)-4.8 x 10(6) IU/m2/day x 5 days/week) and rIFN-alpha (5 x 10(6)-6 x 10(6) U/m2 x 3/week). Before and after therapy, we phenotypically evaluated circulating lymphocytes and correlated them with clinical response. During 6-week therapy, peripheral blood lymphocytes bearing the CD56 (NK-cell-associated) surface antigen were increased significantly (p < or = 0.005) in treatment responders [complete response (CR) and partial response (PR), n = 10; 3.8-fold] and stable disease (SD) patients (n = 20; 2.1-fold), while patients with progressive disease (PD, n = 17) exhibited no significant expansion of circulating NK cells (p > 0.1). After one 6-week treatment cycle, CR/PR patients had significantly more peripheral NK cells, when compared with patients in SD (1.6-fold) and PD (1.9-fold) (p < 0.04). The overall number of circulating lymphocytes was also increased upon therapy (1.6-fold; p < or = 0.001), but remained independent of response (p > 0.4). These data demonstrate that s.c. rIL-2 and s.c. rIFN-alpha produce a significant increase in peripheral blood NK cells; this expansion correlates significantly with treatment response in advanced tumor patients receiving long-term combination immunotherapy at outpatient doses.

In vivo and ex vivo antitumor activity in patients receiving low-dose subcutaneous recombinant interleukin-2.

Alterations in cell-mediated cytotoxicity levels were studied in patients receiving recombinant interleukin-2 (rIL-2) via subcutaneous injection. Fourteen outpatients, aged 36-68 years, with progressive metastatic malignancies, were treated with weekly escalated doses of rIL-2, starting at 1.8 IU/m2/day for 6 days a week, up to 14.4 IU/m2/day during the 4th week of therapy. Patients presenting with stable disease thereafter were started on maintenance therapy and received 10.8 IU/m2 once weekly for up to 12 weeks. Patient mononuclear cells were isolated from fresh peripheral blood at various times throughout the treatment. Cells were assayed prior to and after further in vitro stimulation by rIL-2 (600 IU/ml for 7 days). Natural killing (NK) activity was measured by cytolysis of K 562 target cells, and lymphokine-activated killing (LAK) was determined by cytotoxicity against Daudi targets, respectively, in four effector:target ratios (E:T), using a standard 2-hour europium3+ release assay. Spontaneous NK cell function (E:T = 25:1) of freshly isolated peripheral blood mononuclear cells (PBMC) was enhanced significantly after 28 days of therapy (27.8 vs. 9.1% on day 0). LAK activity also markedly increased during therapy (26.2 vs. 5.4% on day 0). Further in vitro culture of these PBMC in the presence of rIL-2 resulted in day 28 non-MHC-restricted cytolytic activity of 63.2% (40.3% on day 0) against K 562 targets, and 64.9% (39.6% on day 0) against Daudi targets. Activation of cytolytic function by rIL-2 appeared to be dose-dependent, as measurable lytic capability decreased throughout maintenance therapy, while neither sex nor tumor entity prior to therapy or clinical response were correlated with cytotoxicity levels. Taken together, our observations demonstrate that stimulation of the non-MHC-restricted pathway of cytolytic activation, as measured by lysis of target cells, arises in patients treated with rIL-2 doses 5- to 30-fold lower than used previously in intravenous protocols, connecting effective clinical response rates with acceptable tolerability.

Biological monitoring of low-dose interleukin 2 in humans: soluble interleukin 2 receptors, cytokines, and cell surface phenotypes.

Different immunotherapy regimens using s.c. recombinant interleukin-2 (rIL-2) were studied in 76 patients with progressive metastatic renal carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, or Hodgkin's disease. To assess the immunomodulatory capacity of rIL-2, we measured serum levels of soluble interleukin-2 (sIL-2) receptors, gamma-interferon, tumor necrosis factor-alpha, and various lymphocyte subsets expressing the CD25 Tac IL-2 receptor and the CD56 natural killer (NK) associated antigen. Additionally, we measured serum antibodies specific to rIL-2 in order to evaluate immunogenicity of rIL-2. In all patients, a significant increase in sIL-2 receptor levels could be observed when comparing values on day 0 and after one treatment course. Patients developing a neutralizing anti-rIL-2 antibody exhibited significantly lower serum sIL-2 receptor levels than patients without antibody. Soluble IL-2 receptors correlated with the percentage of CD25 IL-2 receptor-positive peripheral blood lymphocytes. Both soluble and cell surface IL-2 receptors exhibited a significant increase during rIL-2 therapy but did not correlate with the percentage of CD56-positive peripheral blood lymphocytes. Measurement of treatment-induced secondary cytokines showed significant increases in gamma-interferon serum levels in a proportion of patients tested, although with considerable interindividual variability. No significant increase in mean tumor necrosis factor-alpha levels was observed during rIL-2 treatment in vivo. The percentage of CD56-positive NK cells correlated with the clinical outcome of rIL-2 therapy. Thus, partial or complete responders had an increase from a mean of 20% NK cells prior to therapy up to a mean of 40% after the first treatment course. In contrast, patients with progressive disease had a mean of 22 and 24% NK cells before and after treatment, respectively.

Diminished expression of interleukin-2 receptors in vivo after prior chemotherapy in advanced cancer patients receiving recombinant interleukin-2.

In a phase I/II dose escalation study performed at our institution, a total of 14 advanced metastatic cancer patients received between 4 and 16 weeks of subcutaneous recombinant interleukin-2. Doses were escalated at weekly intervals, starting at 1.8 million IU/m2/day up to a maximum dose of 14.4 million U/m2 daily. When comparing patients with (n = 4) and without (n = 7) prior chemotherapy on day 0 (i.e., before rIL-2), both patient groups exhibited Tac IL-2 receptor (CD25) positive peripheral blood lymphocytes at equal levels of positivity (8%). In contrast, 4-week systemic treatment with subcutaneous rIL-2 at escalating dose levels revealed a significant difference in the up-regulation by interleukin-2 of CD25 cell surface receptor. Thus, after 4 consecutive weeks of treatment, patients without previous chemotherapy showed a mean CD25 positivity of peripheral blood lymphocytes at 38%, as compared with 22% in patients who did receive prior chemotherapy (p less than 0.05). These data suggest that chemotherapy pretreatment may have a significant effect on biological response to rIL-2 in vivo.