Long-term efficacy and safety of zolpidem extended-release 12.5 mg, administered 3 to 7 nights per week for 24 weeks, in patients with chronic primary insomnia: a 6-month, randomized, double-blind, placebo-controlled, parallel-group, multicenter study.

STUDY OBJECTIVES: To evaluate long-term efficacy and safety of zolpidem extended-release 3 to 7 nights/week for chronic primary insomnia. DESIGN: Multicenter, 25-week, phase IIIb, randomized, double-blind, placebo-controlled, parallel-group. SETTING: Outpatient; visits every 4 weeks. PATIENTS: Aged 18 to 64 years; DSM-IV criteria for chronic primary insomnia; > or =3 months of difficulty initiating or maintaining sleep or experiencing nonrestorative sleep. INTERVENTIONS: Single-dose zolpidem extended-release 12.5 mg (n = 669) or placebo (n = 349), self-administered from a minimum of 3 nights/week to a maximum of 7 nights/week. MEASUREMENTS AND RESULTS: Patient's Global Impression (PGI) and Clinical Global Impression-Improvement (CGI-I) were assessed every 4 weeks up to week 24. Patient Morning Questionnaire (PMQ), recorded daily, assessed subjective sleep measures-sleep onset latency (SOL), total sleep time (TST), number of awakenings (NAW), wake time after sleep onset (WASO), and quality of sleep (QOS)-and next-day functioning. At week 12, PGI, Item 1 (aid to sleep), the primary endpoint, was scored as favorable (i.e., "helped me sleep") by 89.8% of zolpidem patients vs. 51.4% of placebo patients (P < 0.0001, based on rank score) and at week 24 by 92.3% of zolpidem extended-release patients vs. 59.7% of placebo patients. Zolpidem extended-release also was statistically significantly superior to placebo at every time point for PGI (Items 1-4) and CGI-I (P < 0.0001, rank score), TST, WASO, QOS (P < 0.0001), and SOL (P < or = 0.0014); NAW (Months 2-6; P < 0.0001). Sustained improvement (P < 0.0001, all time points) was observed in morning sleepiness and ability to concentrate (P = 0.0014, month 6) with zolpidem extended-release compared with placebo. Most frequent adverse events for zolpidem extended-release were headache, anxiety and somnolence. No rebound effect was observed during the first 3 nights of discontinuation. CONCLUSIONS: These findings establish the efficacy of 3 to 7 nights per week dosing of zolpidem extended-release 12.5 mg for up to 6 months. Treatment provided sustained and significant improvements in sleep onset and maintenance and also improved next-day concentration and morning sleepiness.

New perspectives for the treatment of disorders of sleep and arousal.

A variety of molecules with novel mechanisms of action are currently being evaluated for their potential as treatments for sleep disorders. The GABA-A receptor complex remains an important target for hypnotic drugs (eg gaboxadol, indiplon). However, drugs acting through histamine, calcium channels and serotonin receptors may also be of interest for the treatment of insomnia. In the case of the 5HT2A subtype of serotonin receptors, several molecules which improve sleep maintenance and modify sleep architecture by increasing slow wave sleep are currently being tested (eg eplivanserin). Two new drugs with efficacy in excessive sleepiness (modafinil, sodium oxybate) have improved the treatment of this condition. However, the mechanisms of action of these agents are poorly understood. The recent discovery of the hypocretin arousal system in the hypothalamus may aid the identification of additional new drugs. An agonist at receptors for the pineal hormone melatonin is available in some countries (ramelteon) but is currently used only for the treatment of insomnia associated with difficulties of sleep onset. Additional melatonin receptor agonists are being developed and may have potential for treating several conditions including circadian rhythm disorders and depression.

Virus-free transfer of the herpes simplex virus thymidine kinase gene followed by ganciclovir treatment induces tumor cell death.

We report virus-free transfer of a "suicide" gene into tumoral cells. The system can be used in vitro or in vivo to induce tumor cell death. A plasmid carrying the herpes simplex virus thymidine kinase (HSV-TK) gene with its 5'- and 3'-flanking regions was used both alone and in liposomes to transduce B16 cells. In vitro, a 5-day treatment with ganciclovir after transfection with the HSV-TK gene in liposomes induced a significant lysis of B16 melanoma cells as assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. The efficacy of transfection was determined using liposomes harboring the beta-galactosidase reporter gene and was around 10%. Thus, the cytotoxicity observed resulted presumably from a large bystander effect. In vivo, direct transfer of the TK DNA into established B16 melanoma tumors in C57B6 mice followed by i.p. ganciclovir treatment induced a 50% reduction of tumor weight after 8 days and an increased necrosis. Despite the use of the nonspecific strong TK promoter, no necrosis was detected in normal tissues surrounding the tumor or elsewhere. Thus, this system of tumor transfection, which does not involve any viral vector, is safe and straightforward and seems to be suitable for testing in clinical trials.

Endogenous interleukin 6 levels in patients with metastatic malignant melanoma: correlation with tumor burden.

The involvement of interleukin (IL-) 6 in malignant disease has been investigated in a variety of different malignancies. To evaluate whether serum IL-6 is a useful disease marker in metastatic malignant melanoma (MMM), we studied the time course of endogenous IL-6 secretion in 41 patients treated with cisplatinum, IL-2, and IFN-alpha. Furthermore, the relationship of endogenous IL-6 concentrations to the tumor burden and/or the clinical response was also evaluated. The baseline serum IL-6 levels were significantly higher in patients with MMM than in the control group (P = 0.002). When tumor burden was taken into consideration, we found that IL-6 levels were higher in patients with high tumor burden than in patients with low tumor burden. During treatment in the whole patient population, a higher serum IL-6 level was observed in nonresponding as compared to responding patients at days 7 (P = 0.0005), 21 (P = 0.002), and 35 (P = 0.009). The follow-up of serum IL-6 in patients with MMM according to the tumor burden and clinical response demonstrated that: (a) IL-6 levels were significantly higher at days 7 and 21 in patients with high tumor burden as compared to those with low tumor burden; and (b) IL-6 levels remain significantly higher in nonresponding patients as compared to responding patients regardless of the tumor burden. From these results, we can conclude that endogenous IL-6 may play a role in the failure of IL-2 therapy in such patients, since the very early IL-6 increase is correlated with the tumor mass and nonresponse to biochemotherapy. Therefore, it seems that the early detection of endogenous IL-6 may represent valuable information for monitoring the response to biochemotherapy in patients with MMM.

Effect of the serotonin-4 receptor agonist zacopride on aldosterone secretion from the human adrenal cortex: in vivo and in vitro studies.

We have recently shown that serotonin (5-HT) stimulates cortisol secretion from human adrenocortical tissue in vitro through activation of 5-HT4 receptors. The aim of the present study was to investigate the effect of the 5-HT4 agonist racemic zacopride on aldosterone secretion from the human adrenal gland in vivo and in vitro. In vivo studies were conducted on 28 healthy volunteers pretreated with dexamethasone. The subjects received a single oral dose of placebo, 10 micrograms zacopride, or 400 micrograms zacopride. Plasma aldosterone levels increased significantly within 90 min after the administration of 400 micrograms zacopride, remained elevated for 60 min, and gradually returned to the baseline within 180 min. In contrast, the administration of 10 micrograms zacopride or placebo did not modify the aldosterone concentration. No significant changes were observed in renin, ACTH, or cortisol levels. In vitro studies were conducted on perifused human adrenocortical slices. Administration of 20-min pulses of zacopride (from 10(-11) - 10(-6) mol/L) induced a dose-dependent increase in aldosterone secretion. The minimal effective dose was 10(-10) mol/L, and half-maximal stimulation was obtained with a dose of 7 x 10(-8) mol/L. Zacopride was 100 times more potent in stimulating aldosterone than cortisol release. Taken together, the present data suggest that 5-HT-evoked aldosterone secretion involves the activation of 5-HT4 receptors.

Liposomal delivery of the herpes simplex virus thymidine kinase gene in glioma: improvement of cell sensitization to ganciclovir.

In this study, we investigated whether the regulation and the copy number of the herpes simplex virus thymidine kinase (HSVtk) gene increased the sensitization to ganciclovir (GCV) of glioma cell lines (Rat C6 and human U118-MG) using liposome-mediated gene transfer. Three recombinant plasmids carrying the HSVtk gene driven by the thymidine kinase promoter in single (pAGo) and double copy (pYED) or by the human cytomegalovirus promoter (pCMVtk) were used for the transfection. The DNA delivery was optimized by screening a panel of cationic liposomes using Lac-Z and luciferase as reporter genes. The efficiency of transfection reached 33% to 36% in vitro but only 18.6% in vivo after an intratumoral injection of DNA-liposome complexes. Moreover, after transfection of the three plasmids, the cell-killing effect of GCV was evaluated. A significant enhancement (four- to fivefold) of the cell sensitivity to GCV was shown in pCMVtk and pYED as compared with pAGo-transfected cells in both cell lines. According to the plasmid, the effect of the HSVtk/GCV system was confirmed by in vivo experiments and was objectified by a higher tumor weight reduction with pCMVtk (49%) than pAGo (27%). From these results, we conclude that (1) the gene transfer can be achieved by cationic liposomes both in vitro and in vivo and that (2) using this type of vector, the antitumor effect of the HSVtk/GCV system could be potentiated by the up-regulation of HSVtk gene duplication.

Direct gene transfer of a plasmid carrying the herpes simplex virus-thymidine kinase gene (HSV-TK) in transplanted murine melanoma: in vivo study.

The aim of the study was to use a virus-free system to transfer the Herpes Simplex Virus-thymidine kinase (HSV-TK) gene in mice bearing melanoma tumours. B16 F1 murine melanoma cells were injected subcutaneously. On days 11 and 14, an intratumoral injection of either naked plasmid containing the HSV-TK gene (pAG0) or pAG0-lipofectamine complexes was given. Ganciclovir (120 mg/kg/day) was given for 5 days starting on day 14. Tumour weight reduction (40-50%) was observed in treated animals versus different control groups. Moreover, histopathological analysis on tumours showed large areas of cavitary necrosis (85%) in treated groups compared to controls (10%). Using a simple and safe method, the results presented here demonstrated that virus-free mediated delivery of the HSV-TK gene is efficient in vivo in murine malignant melanoma.

A flow cytometric method for the rapid detection of beta-galactosidase transfected cells: an in vitro and in vivo study.

A flow cytometric method has been developed for the rapid analysis of lacZ transduced cells. The method described is based on an indirect immunofluorescence staining procedure using a monoclonal antibody which binds specifically to beta-galactosidase from E. coli and to beta-galactosidase fusion proteins. This technique was used for the quantification in vitro as well as in vivo of beta-galactosidase expression in B16 melanoma cells. The described method is appropriate for a variety of cell types (species, lineage), is simple, quantitative, reliable, rapid and applicable to all constructs containing the lacZ selectable markers. It should prove to be very helpful (1) for the quantification of cells expressing the lacZ reporter gene and (2) for studying gene regulation, including transfection modality, promoter efficacy, enhancer activity, and other regulatory factors.

Soluble circulating Fc gamma receptors in human serum. A new ELISA assay for specific and quantitative detection.

We have developed a simple, rapid, and sensitive enzyme-linked immunoadsorbent assay (ELISA) to measure soluble cell-free human Fc gamma receptor (Fc gamma R) in serum. This assay is based on the use of two monoclonal antibodies directed against different epitopes expressed on the same low avidity human Fc gamma R (CD16), which is present on polymorphonuclear leukocytes, macrophages and NK cells. This sandwich ELISA, which can measure 2 nM concentration of Fc gamma R, has enabled us to demonstrate the presence and to measure the level of soluble cell-free human Fc gamma R (CfH-Fc gamma R) in normal human serum.

Preliminary results of a phase I/II study of paclitaxel, cisplatin, and cyclophosphamide in advanced ovarian carcinoma.

The clinical activity and toxicity of the triple combination of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), cyclophosphamide, and cisplatin was assessed in both previously treated and untreated women with advanced ovarian carcinoma. Paclitaxel 175 mg/m2 was administered over 3 hours following standard premedication (prednisolone, dexchlorpheniramine, and cimetidine). Cisplatin 80 mg/m2 and cyclophosphamide 600 mg/m2 were given 6 to 12 hours after paclitaxel. Treatment was given at 3-week intervals for six cycles. Twenty-seven patients entered the study; 23 were evaluable for toxicity and 17 for response. Paclitaxel appeared to add additional efficacy to the standard cisplatin/cyclophosphamide regimen. Both the overall and complete remission rates were very high (88% and 70%, respectively), and histologically confirmed complete remissions exceeded 60%. Longer follow-up is needed to determine the duration of these responses. The primary toxicities included leukoneutropenia, peripheral neuropathy, asthenia, and alopecia. Only two of 23 patients withdrew because of toxicity, however, and only two treatment cycles were complicated by neutropenic fever requiring intravenous antibiotics. No life-threatening toxicities were encountered, although the peripheral neuropathy was poorly and slowly reversible and may have a significant impact on the patients' quality of life.

Phase I/II study of paclitaxel, cisplatin, and cyclophosphamide in advanced ovarian carcinoma: preliminary results.

In this phase I/II study, we assessed the impact of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in the treatment of advanced ovarian carcinoma combined with the standard regimen cisplatin/cyclophosphamide given as follows: paclitaxel 175 mg/m2 (over 3 hours perfusion with standard premedication), cisplatin 80 mg/m2 (6 to 12 hours after paclitaxel), and cyclophosphamide 400 mg/m2. From February 1994 to January 1996, 27 patients (median age, 55 years; age range, 35 to 74 years) were entered into the study. Eight patients had distant metastases and 19 had early locoregional disease (stage III, 18 patients; stage IC, one patient). Twenty-two patients had undergone prior surgery (simple biopsy, six patients; optimally debulked, nine patients; suboptimally debulked, seven patients). Twenty-one patients had received no prior chemotherapy and six were previously treated with at least one platinum-based regimen. A maximum of six courses of paclitaxel/cisplatin/cyclophosphamide were given every 21 days. Twenty-three patients were evaluable for toxicity: neutropenia (World Health Organization grade 3/4), 91% of patients; thrombopenia (World Health Organization grade 3/4), 13% of patients; two episodes of neutropenia with fever; and neurotoxicity grade 3, 17% of patients. Alopecia grade 3 was reported in all patients. No hypersensitivity reactions and no cardiac toxicity was observed. Among 17 patients evaluable for response (patients with stage IV disease or stage III suboptimally debulked), 12 (70%) clinical complete responses (CRs) and three (18%) partial responses were observed. Among the 12 patients with CRs, 10 underwent second-look laparotomy and seven of them (70%) achieved a pathologic CR. In the group of 11 chemotherapy-naive patients evaluable for response, eight (72%) achieved a CR and three (28%) achieved a partial response. This combination seems to be safe, with very acceptable toxicity, and also seems to be highly active in the treatment of patients with advanced ovarian carcinoma.

Comparison of the uptake of retinoids 13-cis-retinoic acid and Ro 13-6298 delivered to HL-60 cells by serum albumin or low-density lipoprotein.

Retinoids, a class of polyisoprenoids including retinol and retinoic acid, regulate and control diverse physiological functions via their cell-differentiating and morphogenic potential. In the present study we showed that the extracellular concentration of retinoid-binding proteins such as albumin limits the amount of retinoid entering the human promyelocytic leukemia cell line HL-60. These cells accumulate 5 -10 times more retinoid when delivered free in solution than when bound to either albumin or low-density lipoprotein (LDL). Moreover. the effect of protein binding is concentration-dependent, with a higher concentration of binding protein corresponding to a lower level of cellular uptake. Furthermore, the uptake of the ester derivative is higher than that of the acidic retinoid. These observations suggest that (a) the cellular uptake of both retinoids occurs via the free form of the ligand in solution, with the free concentration of ligand decreasing as the carrier-protein concentration increases, and (b) according to a passive mechanism, the ester derivative, unionized and lipophilic, enters the cells more easily than does the acidic derivative.

Plasma Fas ligand, an inducer of apoptosis, and plasma soluble Fas, an inhibitor of apoptosis, in advanced melanoma.

The transmembrane receptor Fas/APO-1, together with its protein-binding partner (Fas ligand), is a key regulator of programmed cell death and induces apoptosis when it binds Fas ligand (FasL) or soluble Fas ligand (sFasL). However, soluble Fas (sFas) blocks apoptosis by inhibiting binding between Fas and FasL or sFasL. At present, the status of sFas and sFasL in metastatic malignant melanoma remains unknown. This study sought to evaluate the relationship between plasma levels of sFas and/or sFasL and clinical response in 45 metastatic malignant melanoma patients treated by biochemotherapy. sFas and sFasL were measured by specific enzyme-linked immunosorbent assay (ELISA) tests in the sera from patients and 34 healthy donors. Overall, sFas and sFasL levels in patients were significantly higher (P < 0.0001) than in healthy donors. Before the biochemotherapy treatment the sFas level was about the same in biochemorefractory (n = 26) as in responder patients (n = 19). In contrast, the sFasL level was very high only in biochemorefractory patients. At the end of the treatment, in biochemorefractory patients the sFas level was extremely significantly increased (P < 0.0001) and a significant decrease in the plasma levels of sFasL was observed (P = 0.0002). In responder patients, no change in sFas and sFasL was detected. In conclusion, elevated levels of sFas and sFasL might be associated with poor prognosis in advanced melanoma; their possible role in the regulation of apoptosis in influencing the response to biochemotherapy should be further explored.

Serum caspase-1 levels in metastatic melanoma patients: relationship with tumour burden and non-response to biochemotherapy.

Interleukin-1beta converting enzymes (ICEs/caspases) are involved in programmed cell death (apoptosis). This study sought to quantify the caspase-1 level in metastatic malignant melanoma patients and to try to establish a correlation between the level of caspase-1 and different parameters related to this pathology. In addition, we evaluated the possible relationship between the clinical response to biochemotherapy and the caspase-1 level. The serum caspase-1 level was determined in 81 metastatic malignant melanoma patients and 50 normal volunteers using enzyme-linked immunosorbent assay (ELISA). Patients received cisplatin, recombinant interleukin-2 (Proleukin) and alpha-interferon (Roferon A) in two induction cycles, and assessment of clinical response was performed according to World Health Organization (WHO) criteria. The median caspase-1 level in melanoma patients was significantly higher (P = 0.0035) than in control samples. Interestingly, a positive correlation between caspase-1 level and the tumour burden was shown (rs = 0.629, P = 0.009). When the clinical response was taken into consideration, the level of caspase-1 was significantly higher in biochemorefractory patients compared with responding ones (P = 0.04). After treatment, the caspase-1 level remained very high in biochemorefractory patients, while in responding ones no change was observed. Furthermore, a positive correlation between the clinical response and the caspase-1 level was established (rs = 0.404, P = 0.024). In conclusion, we observed an elevated caspase-1 level in metastatic malignant melanoma patients. In addition, the correlations obtained between the caspase-1 level and both the tumour burden and the clinical response to the treatment support the concept that disrupted apoptosis pathways might be involved in the progressive disease of advanced melanoma and/or may confer resistance to treatment.

Is there any relationship between interleukin-6/interleukin-6 receptor modulation and endogenous interleukin-6 release in metastatic malignant melanoma patients treated by biochemotherapy?

During recent years it has become clear that the production of most cytokines could play an important role in malignancies. We previously demonstrated that a high endogenous interleukin-6 (IL-6) level is significantly correlated with a high tumour burden and resistance to biochemotherapy in metastatic malignant melanoma patients. However, little is known about the origin of IL-6 and the pattern of IL-6 receptor (IL-6R) expression. In this report, we studied the expression of IL-6R and intracellular IL-6 using flow cytometry in tumour cells provided by fine-needle aspiration of lymph nodes and palpable metastatic lesions from 14 patients refractory to biochemotherapy and six responder patients. Moreover, we established the relationship between these parameters and the serum IL-6 level. Our results demonstrated that, following treatment, the percentage of HMB45-positive (HMB45+) cells expressing functional IL-6R, intracellular IL-6 or both IL-6R and IL-6 significantly decreased in patients refractory to biochemotherapy. In contrast, in responder patients the percentage of HMB45+ cells expressing IL-6R increased and those expressing IL-6 remained stable. Regarding the serum IL-6 level, an 11-fold increase was observed in the patients refractory to biochemotherapy, but only a 1.8-fold increase in the responder patients. In conclusion, in metastatic malignant melanoma patients with a poor prognosis, the endogenous production of IL-6 is concomitant with a decrease in functional IL-6R and intracellular IL-6 expression, suggesting the involvement of an IL-6/IL-6R complex.

Fotemustine, dacarbazine, vindesine combination chemotherapy in advanced malignant melanoma: a phase II study of 43 patients.

Fotemustine and dacarbazine constitute the most active single chemotherapeutic agents in the treatment of melanoma. In this phase II study we evaluated the activity and toxicity of a combination of fotemustine, dacarbazine and vindesine as a means of increasing response rate and survival time. Between September 1989 and November 1993, 43 patients with advanced melanoma were treated with a combination of 100 mg/m2 fotemustine on days 1 and 8, 250 mg/m2 dacarbazine on days 15 and 16 and 2 mg/m2 vindesine on days 15 and 16 as induction treatment. After a 5-week rest period, the patients exhibiting a response or stable disease received the same drugs administered once every 28 days as maintenance therapy until either progression or toxicity was observed. Among 41 evaluable patients, there were six complete responses and eight partial responses. The overall response rate was 32% (95% confidence interval: 18-46%), with 8 months median duration of response. Median survival time was 10 months. This regimen was well tolerated. From this large phase II study, we conclude that such a combination is active against advanced malignant melanoma and seems to be more effective than fotemustine or dacarbazine used alone, especially on visceral metastatic sites.

Effects of tiapride on electroencephalograms and cognitive functions in the elderly.

Tiapride is a substituted benzamide with selective dopamine D2 and D3-antagonist properties which appears to have preferential affinity for extra-striatal dopamine receptors. Tiapride is used in the treatment of agitation, aggressiveness and anxiety in the elderly. To define the effects of a single dose of tiapride 100 mg on psychomotor performance and cognitive functions and electroencephalogram (EEG), a randomized, double-blind, three-way crossover, placebo-controlled study using lorazepam 1 mg as a positive control was carried out in 12 elderly individuals (six women and six men, mean age +/- SD: 69 +/- 3 years). A 1-week wash-out interval was allowed between each administration. Psychomotor and cognitive functions were assessed using both objective [EEG, critical flicker fusion, simple reaction time, tapping, body sway, continuous performance task (CPT), digit symbol substitution test, Sternberg memory scanning and a learning memory test using word lists] and subjective (visual analogue scales) measures before and up to 6 h after dosing. Tiapride was devoid of any detrimental or sedative effects on EEG and all of the performance tasks used and did not impair memory compared with-placebo. In contrast, a single dose of lorazepam produced significant deleterious effects on psychomotor performance (decrease in tapping and in sustained attention (CPT) and an increase in reaction time and body sway), and sedative effects on EEG (significant increase in delta and decrease in alpha waves) as well as significant impairment in working memory (Sternberg) and anterograde amnesia (decrease in immediate and delayed free recall) up to 6 h after dosing compared with placebo and tiapride. In conclusion, the present study showed that in contrast to lorazepam 1 mg there is no evidence to suggest that a single dose of tiapride 100 mg has any sedative and amnestic effects in the elderly which may interfere with everyday life activities.

A phase II study of tamoxifen combined with cisplatin-interleukin 2 and alpha-interferon in metastatic melanoma.

Tamoxifen (TAM) has been reported to enhance cisplatin (CDDP) cytotoxicity in experimental and clinical melanoma studies. Based on our previous experience with sequential cisplatin-interleukin-2 (IL2)-interferon (IFN), we performed a phase II study of TAM combined with our original CDDP-IL2-IFN regimen in 22 pretreated metastatic melanoma patients. With a 41% response rate (95% CI, 21-61) we confirmed the interesting antitumor activity of CDDP-IL2-IFN combination; however, TAM enhanced neither the response rate nor the duration of response, but appeared to induce significantly more myelotoxicity, as compared to our previous results with CDDP-IL2-IFN alone. Whereas mechanisms by which TAM may modulate CDDP cytotoxicity in melanoma tumors remain unknown, the exact place of TAM, if any, and its safety in chemotherapeutic or chemoimmunotherapeutic combinations require further investigations.

[LAK cells and immunotherapy of cancer]. / Cellules LAK et immunothérapie des cancers.

Cancer immunotherapy still appears very unsatisfactory in humans. However, it has been shown recently that Interleukin 2 (IL2) could be used to generate, in vitro as well as in vivo, a new anti-tumoral activity directed against fresh tumor cells, allogenic as well as autologous, both of leukemic and solid tumor origin. This activity is not connected with the NK activity, but with a lymphocyte sub-population termed 'Lymphokine Activated Killer (LAK) Cells'. The exact nature of these LAK cell precursors is still a matter of controversy: 'nul' lymphocyte, T or NK markers bearing lymphocytes, or different precursors according to the system of activation that has been used. However, after being activation, these LAK cells always express T cell-markers. The activation has a very short lifespan, explaining the need for a prolonged contact of the cells with IL2, and therefore the necessity to continue injecting the lymphokine in vivo. The clinical results that have been reported so far are still very preliminary. The most common treatment protocol consists of 5 days of IL2 injections followed by 5 days of leukapheresis and in vitro activation of the collected cells, and then auto-transfusion of the activated cells and IL2 during the next 5 days. The clinical toxicity encountered is impressive in terms of frequency as well as severity. Clinical activity seems to be relatively weak. Nevertheless, the concept still appears to be very promising.

[Cancer and immunosuppression : experimental aspects]. / Cancer et immunodépression : aspects expérimentaux.

The hypothesis that immunodepression favors a carcinogenetic process and thus subsequent tumor development remains controversial in spite of numerous experimental studies. This is due, on one hand, to the difficulty in demonstrating the presence of tumor-associated antigens and, on the other, to the complex immunological mechanisms which lead to the destruction of tumors cells. With respect to immunosurveillance, the present situation can be summarized as follows: the development of virus-induced tumors is under the control of a T-cell dependent system; a T-cell depression (thymectomy, congenital absence of thymus, anti-lymphocytic serum) increases the number of these tumors; chemically induced tumors or spontaneous tumors are under the control of non-specific effectors such as macrophages and NK cells; NK cell deficiency (of congenital origin such as in beige mice) or acquired (chemically induced) increases tumor growth; carcinogens can induce general immunodepression (chemical carcinogenesis) or stimulate specific suppressive cells (U.V. radiation) thus allowing tumors development. The tumors being established, it may itself contribute to an immunodepressive state thus fostering its growth through the activity of: immune complexes; specific or non specific suppressive cells; an increase in the level of alpha 2-globulin immunosuppressive molecules which are present under normal conditions; a release of several factors acting at different levels such as prostaglandin E, anti-inflammatory factors acting on monocytes, etc. The apparition of an antigenic and immunogenic tumor heterogeneity due to development of new clones will also modify host-tumor relationships. The complexity of the immunological mechanisms which are involved in the control of tumor growth may explain the variable results of immune prevention and of the immunotherapy of cancer.