Characterization of the indirect antitumor effect of gamma-interferon using ascites-associated macrophages in a human tumor clonogenic assay

The indirect antitumor effects of recombinant gamma-interferon (IFN-gamma) were investigated using an in vitro tumor clonogenic assay modified to include ascites-associated macrophages (AAM). Untreated AAM stimulated tumor colony growth; conversely, AAM treated with IFN-gamma at clinically achievable doses demonstrate a significant growth-inhibiting effect. The indirect antiproliferative activity was dependent on the density of AAM. Supernatants from IFN-gamma-pretreated AAM cultures derived from 11 different ovarian cancer patients significantly inhibited the colony growth of ovarian cancer cell line BG-1, as well as five of six other cell lines. Physicochemical characteristics of the supernatant indicated that a significant part of the antiproliferative activity is heat sensitive, destroyed by proteolytic enzymes, and is dependent on RNA and protein synthesis for production. Neutralizing antiserum against tumor necrosis factor significantly reduced the antiproliferative activity of the supernatants. Production of this factor by AAM was induced by exposure to 1000 units/ml of IFN-gamma for 15 min, although activity in the supernatants was not detected until 8 h after exposure to IFN-gamma. Potency of the supernatants reached a peak 12 h after priming and ceased by 22 h. Production of antiproliferative activity was maintained over 5 days by intermittent treatment of AAM with IFN-gamma. Combinations of IFN-gamma and supernatant from IFN-gamma-treated AAM showed potentiated antiproliferative activity against BG-1 in an additive to synergistic manner. Antitumor effects of IFN-gamma may be dependent on tumor-associated macrophages and treatment scheduling.     

Direct and indirect effects of human recombinant gamma-interferon on tumor cells in a clonogenic assay

Purified, recombinant human gamma-interferon (rIFN-gamma) was tested at clinically achievable doses for direct and indirect antiproliferative activity against human tumor cell lines using a clonogenic assay. One-h treatment with rIFN-gamma showed direct dose dependent inhibition of tumor colony growth in cell lines established from human melanoma, myeloma, renal cell, and cervical cancers. Longer treatments resulted in suppression of ovarian and breast carcinoma clonogenicity. In order to test for indirect antiproliferative effects of rIFN-gamma, feeder cells were included in a separate agarose underlayer in the cloning assay. These feeder cells included mouse peritoneal macrophages, U-937 (human histiocytic lymphoma cell line), and adherent cells from human malignant ascites specimens. Colony growth of ovarian carcinoma and melanoma cell lines was stimulated by each of these feeder cell types. Cultures containing mouse peritoneal macrophages or U-937 cells showed the same antiproliferative responses to rIFN-gamma as did control cultures without feeder cells. In contrast, human adherent ascites cells (greater than 80% macrophages) became strongly inhibitory to tumor colony growth when treated with rIFN-gamma. These results suggest that human tumor associated macrophages may become tumoricidal under the influence of rIFN-gamma, producing a diffusable substance in agarose culture which causes the observed antiproliferative effects on tumor cells.     

Studies on the antitumor activity of human recombinant interferon alpha-2b in vitro

Correlation between antiproliferative and binding activities of interferon (IFN) alpha-2b to various human cell lines was examined using human recombinant IFN alpha-2b. Burkitt's lymphoma Daudi cells and human renal cell carcinoma OS-RC-2 cells were sensitive to IFN alpha-2b, whereas two EB-virus-transformed B cell lines, FS and L-KT3, and human A375 melanoma cells showed low or no sensitivity. 125I-IFN alpha-2b binding assay revealed that the difference in IFN alpha-2b sensitivity was related to the number and the affinity of IFN alpha-2b receptors per cell. Experiments were then performed to investigate the influence of recombinant IFN alpha-2b on the cytostatic activity of monocytes against A375 cells in vitro. IFN alpha-2b enhanced the cytostatic activity of monocytes against A375 cells which showed low sensitivity to the direct growth inhibitory effect of IFN alpha-2b. Depletion of NK cells from the monocyte preparations by anti-Leu-11b monoclonal antibody and complement did not affect the monocyte activation by IFN alpha-2b, indicating that NK cells were not involved in this system.     

Combined recombinant human interferon alpha 2 and cytotoxic agents studied in a clonogenic assay

A human tumor clonogenic assay has been used to test the antiproliferative effect of recombinant human leukocyte interferon alpha 2 alone and in combination with each of 8 cytotoxic agents. Cell lines derived from 6 human tumors and primary tumor cells from 13 patients have been used in these clonogenic assay studies. Results show that interferon as a single agent causes insignificant reduction in tumor cell colony survival if the short-term 1-hr cell exposure method is used; only high concentrations of interferon used in continuous cell exposure in the clonogenic assay can demonstrate a reduction in colony survival to below 50% of control values. Combinations of interferon with either doxorubicin or cisplatin frequently show additive and occasionally synergistic antiproliferative effects on tumor cell colony formation. Variations in drug concentrations and sequencing of drugs have been tested, showing that optimal antiproliferative effects of combined interferon and doxorubicin are realized when maximal concentrations of interferon and prolonged cell exposure time of both interferon and doxorubicin are employed. Combinations of interferon and doxorubicin tested in the clonogenic assay demonstrate cytotoxicity superior to that of either agent tested alone.     

Assessment of the combined effects of mitomycin C with alpha-interferon or gamma-interferon by the clonogenic assay technique

The combined effects of Mitomycin C (MMC) with alpha-interferon (HLBI) or gamma-interferon (TRP-2), which have become attractive drugs for use as Biological Response Modifiers, were investigated using the human tumor clonogenic assay technique. Tumors in this study were five human tumor xenografts serially transplanted into nude mice (three gastric cancer, two colon cancer). When the survival fraction occurring with the combination was smaller than that obtained by multiplication of the survival fractions occurring with either drug alone, the combined effect was considered to be synergism. Four out of five xenografts (three gastric cancer, one colon cancer) showed synergistic effects for the combination of MMC with alpha-interferon. Although two gastric cancer xenografts showed synergism for the combination of MMC with gamma-interferon, antagonistic effects were observed in one gastric cancer and one colon cancer xenograft.     

Effect of hyperthermia on the antiproliferative activities of murine alpha-, beta-, and gamma-interferon: differential enhancement of murine gamma-interferon

Fever is frequently an important side effect of interferon (IFN) therapy. Studies have shown that culturing interferon-treated cells at elevated temperature heightens the antiproliferative activity of IFN-alpha and IFN-beta. Since IFN-gamma has also been shown to be a potent antiproliferative agent, the effect of elevated temperature on IFN-gamma activity was compared to its effect on IFN-alpha and IFN-beta. Mouse B-16 melanoma cells were simultaneously cultured under cloning conditions at a range of temperatures (37.3, 38.1, 38.6, and 39.4 degrees C) in the presence of MuIFN-alpha, MuIFN-beta, and MuIFN-gamma. The antiproliferative activities of all three interferons were enhanced by incubation at the elevated temperatures. However, the elevated temperatures had a more dramatic enhancing effect on the antiproliferative activity of MuIFN-gamma (10-fold enhancement) than of either MuIFN-alpha or MuIFN-beta (2.9- and 3.4-fold enhancement, respectively). Next, the enhancing effect of elevated temperature (39.4 degrees C) was examined for a range of interferon concentrations. The degree of the enhancing effect increased with increasing concentrations of MuIFN-gamma but not with increasing concentrations of MuIFN-alpha or MuIFN-beta. Enhancing effects of temperature as high as 14-fold were observed for 100 units of MuIFN-gamma/ml. This dramatic enhancement was observed for both natural and recombinant MuIFN-gamma and was neither a function of greater relative perception of MuIFN-gamma titer at elevated temperature nor a function of greater relative stability of MuIFN-gamma at the elevated temperature. The differential enhancement of MuIFN-gamma activity by elevated temperature appeared to be specific for the antiproliferative activity, since the antiviral activity of MuIFN-gamma was not relatively more enhanced at 39.4 degrees C than were the antiviral activities of MuIFN-alpha and MuIFN-beta. These results suggest that fever may be an important factor in maximizing the antitumor effects of MuIFN-gamma and perhaps of human IFN-gamma. They also raise the possibility that a combination treatment regimen of hyperthermia and interferon therapy, particularly IFN-gamma therapy, may provide a significant antitumor effect.     

Pegylated recombinant interferon alpha-2b vs recombinant interferon alpha-2b for the initial treatment of chronic-phase chronic myelogenous leukemia: a phase III study.

Recombinant interferon alpha-2b (rIFN-alpha2b) is an effective therapy for chronic-phase chronic myelogenous leukemia (CML). Polyethylene glycol-modified rIFN-alpha2b is a novel formulation with a serum half-life ( approximately 40 h) compatible with once-weekly dosing. This open-label, noninferiority trial randomized 344 newly diagnosed CML patients: 171 received subcutaneous pegylated rIFN-alpha2b (6 microg/kg/week); 173 received rIFN-alpha2b (5 million International Units/m2/day). Primary efficacy end point was the 12-month major cytogenetic response (MCR) rate (<35% Philadelphia chromosome-positive cells). Modified efficacy analysis included all MCRs >12 months, except for patients discontinuing treatment after 6 months and achieving an MCR on other salvage therapy. The MCR rates were 23% for pegylated rIFN-alpha2b vs 28% for rIFN-alpha2b in the primary efficacy analysis and 26 vs 28% in the prospectively modified efficacy analysis. However, a significant imbalance in baseline hematocrit (HCT), a significant predictor of cytogenetic response (P=0.0001), was discovered: 51 (30%) patients treated with pegylated rIFN-alpha2b had low HCT (<33%) vs 33 (19%) rIFN-alpha2b-treated patients. Among patients with HCT >33%, the MCR rate was 33 vs 31%. The adverse event profile of weekly pegylated rIFN-alpha2b was comparable to daily rIFN-alpha2b. Once-weekly pegylated rIFN-alpha2b is an active agent for the treatment of newly diagnosed CML with an efficacy and safety profile similar to daily rIFN-alpha2b, although statistical noninferiority was not demonstrated.     

Pharmacokinetics of an extended-release human interferon alpha-2b formulation

The in vivo half-life of human interferon alpha-2b (hIFN--2b) is relatively short, and frequent injections over prolonged periods are required for efficacy. An extended-release formulation of hIFN--2b (Depo/IFN) was created by encapsulation into a lipid-based drug-delivery system. The capture efficiency was 51%±13% and the release half-life in human plasma at 37°C was 16 days. The pharmacokinetics of Depo/IFN was compared with that of unencapsulated standard hIFN--2b (Std/IFN) in the peritoneal cavity of male BDF₁ mice. Depo/IFN exhibited a 13-fold longer intraperitoneal (i.p.) half-life as compared with Std/IFN (20 vs 1.5 h). The release of free hIFN--2b from Depo/IFN into the peritoneal cavity was slow and protracted, with a 10-fold lower peak concentration and a 13-fold longer apparent half-life being observed in comparison with Std/IFN. The areas under the curve of free hIFN--2b in the peritoneal cavity were comparable for Depo/IFN and Std/IFN. hIFN--2b was detectable in plasma only after the i.p. administration of Std/IFN. These data suggest the possibility that Depo/IFN may be useful as an extended-release formulation of hIFN--2b.     

Antineoplastic effects of tumor necrosis factor alone and in combination with gamma-interferon on tumor biopsies in clonogenic assay

Tumor colony-forming cells were grown from fresh biopsy specimens from 102 patients with a variety of nonhematologic malignant neoplasms and exposed in vitro to pharmacologically achievable doses of recombinant human tumor necrosis factor (rTNF). In 68 instances, the tumor specimens were also tested against recombinant human gamma-interferon (rIFN-gamma), as well as the combination of rTNF and rIFN-gamma. rTNF exhibited dose-dependent and tumor-type-dependent antitumor effects. Sensitivity to rTNF at doses of less than 100 U was observed in 28% of the tumors tested. A higher than average frequency of sensitivity was observed in colorectal and lung cancer. Resistance to rTNF was observed in 42% of the tumors, including 52% of the ovarian cancer specimens tested. In paired experiments, exposure of tumor specimens to rTNF and rIFN-gamma in combination often resulted in a greater antitumor effect than was observed with either agent alone, with at least subadditive effects seen in 62% of the specimens tested against the combination. Antagonism between rTNF and rIFN-gamma was observed in 18% of the studies. Overall, exposure to the combination of rTNF and rIFN-gamma reduced the dose of rTNF required for significant antitumor activity by about threefold. Normal bone marrow granulocyte-macrophage colony-forming cells were also tested against both rTNF and rIFN-gamma and the combination. The bone marrow progenitors were more sensitive to rTNF and the combination with rIFN-gamma than were the tumor cells; however, the significance of this comparison between two different in vitro assay systems is indeterminate. Based on our observations, rTNF warrants phase II clinical trials in selected solid tumors with definite emphasis on colorectal and lung cancer. Additionally, studies of the combination of rTNF and rIFN-gamma are indicated and will be of particular interest in endometrial and breast cancer.     

吲哚美辛对干扰素α-2b联合小剂量阿糖胞苷治疗慢性粒细胞白血病的影响

 【摘要】　目的　探讨吲哚美辛对干扰素α-2b（IFNα-2b）联合小剂量阿糖胞苷（LD-Ara-C）治疗慢性粒细胞白血病慢性期（CML-CP）患者的影响。方法　22例CML-CP患者按随机数字表法分为 2组：对照组10例,用IFNα-2b 300万U,皮下注射,隔日1次,连用3～18个月,Ara-C 30 mg／d缓慢静脉滴注,10 d为1个疗程,间歇2周,WBC≥20×109／L时,用羟基脲控制;WBC＜20×109／L时停用。治疗组12例,在IFN使用当天增加吲哚美辛25 mg 3次／d,其他治疗与对照组相同。两组均以血液学完全缓解为观察终点,比较两组WBC开始下降时间、WBC降至正常所需时间、外周血幼稚细胞达正常所需时间、达血液学完全缓解所需时间和注射IFN前３d最高体温。结果　治疗组和对照组WBC开始下降时间分别为（4.2±2.7）d和（5.0±2.5）d（t＝0.714,P＞0.05）,WBC降至正常所需时间分别为（10.0±4.5）d和（12.0±4.5）d（t＝1.036,P＞0.05）;治疗组和对照组外周血幼稚细胞达正常所需时间分别为（14.2±4.8）d和（19.0±3.6）d,差异有统计学意义（t＝2.609,P＜0.02）;治疗组和对照组达血液学完全缓解所需时间分别为（45.8±5.6）d和（53.9±10.5）d,治疗组优于对照组（t＝2.314,P＜0.05）。两组注射IFN后发热程度治疗组改善显著优于对照组（χ2＝12.041,P＜0.005）。结论　吲哚美辛与IFNα-2b联合LD-Ara-C治疗CML-CP,不仅能缓解IFN流感样不良反应而且有协同抗白血病作用。     

The feasibility of adjuvant interferon alpha-2b in children with high-risk melanoma

BACKGROUND: It has been shown that induction high-dose interferon alpha-2b (IFN-alpha-2b) followed by maintenance therapy improves recurrence-free survival in adults with high-risk, resected melanoma. In this study, the feasibility and toxicity of this regimen were evaluated in newly diagnosed pediatric patients with Stage III melanoma involving regional lymph nodes. METHODS: Fifteen patients age 相似文献   

重组干扰素α—2b治疗晚期恶性肿瘤的作用

目的为验证干扰素α－２ｂ治疗晚期恶性肿瘤的疗效和毒性,用重组干扰素α－２ｂ（ｒ－ＩＦＮα－２ｂ）治疗恶性肿瘤１０２例。方法采用ｒ－ＩＮＦα－２ｂ肌肉注射,每周２次,第１周３×１０６ＩＵ／次;第２周６×１０６ＩＵ／次;第３～８周９×１０６ＩＵ／次。结果９０例可评价疗效的患者中,总有效率为１６．７％（１５／９０）,其中肾癌的有效率为１０．８％（４／３７,２例ＣＲ,２例ＰＲ）,恶性黑色素瘤的有效率为１４．３％（４／２８,４例ＰＲ）,恶性淋巴瘤的有效率为４／８（４例ＰＲ）,乳腺癌的有效率为３／１５（３例ＰＲ）,２例多发性骨髓瘤均无效。ＣＲ患者的中位缓解期为４０个月,而ＰＲ患者的中位缓解期只有４．８个月。主要不良反应为流感样症状,胃肠道反应和较轻微骨髓抑制。结论ｒ－ＩＦＮα－２ｂ具有一定抗肿瘤活性,可以将其作为第二线药物治疗肾癌、黑色素瘤及恶性淋巴瘤。     

A phase II trial of recombinant interferon alpha-2b and cisplatin in metastatic melanoma

In this phase II study 37 patients with metastatic melanoma were treated with cisplatin 100 mg/m2 every three weeks and interferon alpha-2b 10 MU subcutaneously three times weekly; 125 cycles were administered. Thirty-four patients were evaluable for response and all 37 patients were assessable for toxicity. Four patients stopped treatment with cisplatin because of severe nephrotoxicity, and six patients stopped therapy because of other toxicities. Response rate was 6/34 = 18% (95%) CI (confidence interval): 7%-35%). One patient reached complete response lasting 27+ months. Five patients obtained partial responses with a median duration of response of 7 months (range 5-15+ ). Median time to progression was 2.3 months (range 1-27+). Median survival was 5 months (range 1-27+). We conclude that the combination of high-dose cisplatin 100 mg/m2 and interferon alpha-2b is associated with unacceptable toxicity. Haematological toxicity and nephrotoxicity were pronounced and the response rate was meagre and not encouraging.     

A phase I study of recombinant human interferon alpha-2b combined with 5-fluorouracil and cisplatin in patients with advanced cancer

To determine the maximum tolerated dose (MTD) of escalating doses of interferon--2b (IFN, Intron A) with 5-fluorouracil (5-FU) and cisplatin (DDP) in patients with advanced cancer, 15 patients were accrued between May 1990 and July 1991. Primary sites were unknown (3), colorectal (3), head and neck (2), lung (2), gynecologic (1), gallbladder (1), sarcoma (1), anal canal (1) and pancreas (1). IFN was given s.c. on days 1–5 and then three times weekly with DDP (75 mg/m², day 1) and 5-FU [750 mg/m², days 1–5, continuous infusion (CI) on a 28-day cycle. The first two patients treated at level I (3×10⁶ U/m² s.c.) experienced possible neurotoxic deaths [massive cerebrovascular accident (CVA) and metabolic encephalopathy], and patient 3 had a grade 4 toxicity of performance status decline. Analysis of these events led us to exclude the enrollment of patients on i.v. morphine and of those with prior exposure to DDP. This resulted in grade 3 toxicity in terms of nausea, vomiting, fatigue and leukopenia but in no further CNS event. All patients were evaluable for toxicity but only ten were evaluable for response. Only two partial responses were seen, one in a patient with an unknown primary tumour and one in a patient with head and neck cancer. The combination of IFN is possible with 5-FU and DDP. The recommended dose of IFN is 2×10⁶ U/m² s.c. in patients with no prior exposure to DDP or i.v. morphine, given together with 5-FU (750 mg/m², days 1–5, CI) and DDP (75 mg/m², day 1) on a 28-day cycle.Supported in part by a grant from Schering Canada Inc.     

Thyroiditis after treatment with interleukin-2 and interferon alpha-2a

Serial thyroid functions studies were carried out in patients with melanoma and renal cell carcinoma treated with interleukin-2 (3 MU m-2 by continuous infusion days 1-4) and interferon alpha-2a (6 MU m-2 subcutaneously on days 1 and 4), both given on alternate weeks. The results on eight patients who completed at least three cycles of treatment are described. Four patients developed thyroid dysfunction with a hyperthyroid phase of 2 weeks followed by a hypothyroid phase ranging from 12 to 24 weeks. Two patients became clinically symptomatic and required treatment. Fine-needle aspirates of the thyroid were obtained in three patients with thyroid dysfunction. The cytology revealed a mixed cellular infiltrate with lymphocytes and histiocytes, and immunocytochemical staining showed strong HLA-DR expression of all thyrocytes, both suggestive of an autoimmune thyroiditis. One patient with thyroiditis developed anti-thyroglobulin antibodies, the serology of all other patients was normal. Patients with thyroid dysfunction tended to have higher in vivo stimulated lytic activity of peripheral mononuclear blood cells and had significantly higher levels of CD16 positive blood cells as compared to euthyroid patients. The possibility of autoimmune thyroiditis should be anticipated in future trails combining interleukin-2 and interferon alpha-2a.     

大剂量干扰素辅助治疗国人口腔粘膜恶性黑色素瘤的临床研究

目的 探讨大剂量干扰素辅助治疗口腔粘膜恶性黑色素瘤的疗效和安全性。方法 回顾性分析2004年5月至2012年11月我科经治的Ⅲ～ⅣA期口腔粘膜恶性黑色素瘤患者的治疗及预后情况。在经治的117例患者中,73例术后接受了大剂量干扰素α-2b治疗,其中有58例完成了治疗计划,设为治疗组,另15例中途停止;其余44例未采用大剂量干扰素治疗者作为对照组。比较两组患者的总生存期（OS）和无复发生存期（RFS）以及相关不良反应的发生情况。结果 117例患者的中位OS为40个月（95％CI：33～62个月）。治疗组与对照组中Ⅲ期患者的中位OS（69个月vs.65个月）和RFS（50个月 vs. 34个月）的差异均无统计学意义（P＞0.05）,治疗组与对照组中ⅣA期患者的中位OS（37个月 vs. 20个月）和中位RFS（33个月 vs. 10个月）的差异均有统计学意义（P＜0.05）,治疗组与对照组中Ⅳ期伴颈淋巴结转移患者的中位OS（40个月 vs. 20个月）和中位RFS（33个月 vs. 10个月）的差异均有统计学意义（P＜0.05）。大剂量干扰素治疗的常见血液学毒性为骨髓抑制,包括白细胞减少和血小板减少;非血液性不良反应包括流感样症状、恶心呕吐、肝功能损害等。全组患者不良反应以1～2级为主,仅有7例出现3～4级毒副反应,给予对症治疗后均能缓解,无治疗相关性死亡。结论 术后大剂量干扰素辅助治疗能显著提高ⅣA期口腔粘膜恶性黑色素瘤患者的OS和RFS,且治疗的不良反应可耐受。     

Effects of human recombinant alpha 2 arg-interferon and gamma-interferon on human breast cancer cell lines: dissociation of antiproliferative activity and induction of HLA-DR antigen expression

Human recombinant gamma-interferon (rhu-IFN-gamma) and human recombinant alpha-interferon (rhu-IFN-alpha 2 arg) with a chemical purity of over 95% were compared for their antiproliferative and HLA-DR-inducing activity in five human breast cancer cell lines (BT 20, ZR 75.1, MCF 7, 734B, Hs578T). Cytostatic effects on tumor cells were evaluated in monolayer cultures. HLA-DR antigen expression was examined by an indirect immunofluorescence technique using two different anti-HLA-DR monoclonal antibodies (anti-HLA-DR, VID-1) against framework determinants. rhu-IFN-gamma and rhu-IFN-alpha 2 arg differed in their antiproliferative efficiency in terms of both dose dependency and the spectrum of sensitive target cells. Combinations of rhu-IFN-gamma and rhu-IFN-alpha 2 always resulted in higher cytostatic effects. HLA-DR expression was exclusively inducible by rhu-IFN-gamma and did not correspond to its antiproliferative activity. Furthermore, HLA-DR expression did not depend on proliferation but did require intact RNA and protein syntheses as shown by inhibition with cycloheximide and actinomycin D. HLA-DR antigen expression in mammary cancer lines was dependent on time, dose, and the continued presence of rhu-IFN-gamma. Thus, our data suggest that in particular combinations type I and type II interferons might be useful in the treatment of breast cancer because they provide effective cytostatic and cell membrane-modulating properties.     

The maintenance of busulphan-induced remissions in chronic granulocytic leukaemia with recombinant interferon alpha-2b

Interferon (IFN) shows no specificity in inhibiting the growth of colonies of myeloid leukaemia blasts in culture as compared to normal haemopoietic precursors, but does reduce the self-renewal capacity of myeloblasts. We have tested the ability of IFN to slow the leukocyte doubling time (Ldt) and to prolong remissions induced by busulphan in 14 patients with chronic granulocytic leukaemia (CGL). Patients served as their own controls; the Ldt during relapse from a busulphan-induced remission on no therapy was determined and compared with the Ldt on IFN maintenance therapy. The initial dose of IFN (2 x 10(6) U M-2 subcutaneously, three times per week) was adjusted up, or down, to prevent the leukocyte count from rising and the platelet count from falling below 75 x 10(9) l-1. The dose of IFN required to prevent relapse in seven patients ranged from 1 x 10(6) U M-2 three times per week to 5.2 x 10(6) U M-2 daily, with a median of 2 x 10(6) U M-2 three times per week. IFN maintenance therapy has prevented relapse in six patients for more than 22 months to more than 68 months. In five patients the Ldt was slowed initially but the disease later progressed in four patients to enter the accelerated (three patients) or blast phase (one patient). The Ldt during IFN therapy did not change from the Ldt on no therapy in one patient; this patient later progressed to the blast phase. In two additional patients the leukaemia progressed during the first course of IFN, with shortening of the Ldt; both of these patients entered the blast phase. In the four patients who have discontinued IFN following relapse in the chronic phase, the Ldt remained prolonged for at least one relapse after the IFN was stopped. IFN maintenance therapy failed to control the leukocyte count in the six patients with a control Ldt of less than 40 days and five of these have progressed to enter the accelerated or blast phase. The early survival of this group of patients resembles the survival of 'good risk' CGL patients reported by others. We conclude that IFN maintenance therapy does alter the relapse pattern of a subset of CGL patients, either slowing the Ldt or preventing relapse.     

Pharmacokinetic interaction of 5-fluorouracil and interferon alpha-2b with or without folinic acid

The purpose of this study was to evaluate a potential pharmacokinetic (PK) interaction between fluorouracil (5-FU) and the biomodulating agent interferon alpha (IFN-α) in patients with metastatic colorectal carcinoma. 5-FU was applied as an intravenous bolus injection of 750 mg m^?2 weekly and IFN-α 2b (IFN) 5 MU was injected 3 times weekly (TIW) subcutaneously. In the first study, 13 patients were treated by this schedule, 5-FU plasma levels were determined by HPLC on day (d) one as baseline before starting IFN; the analysis was repeated at the second or third cycle of 5-FU administration 1 hour after the last IFN injection respectively. In the second study, 10 patients additionally received folinic acid (FA) 200 mg m^?2 as a short time infusion immediately before 5-FU, and a third analysis of FU kinetics was performed in order to compare the influence of a double modulation of IFN and FA to IFN alone. Combination of 5-FU and IFN resulted in a significant increase of the AUC of 5-FU (80%) and the fictive initial concentration (C₀, 65%) obviously caused by a reduction of 5-FU clearance by 50%. However, when FA was added to this schedule, no significant changes of FU kinetics compared to 5-FU alone could be documented. Finally, in two pilot patients 5-FU 750 mg was given as a continuous infusion (CI) over 5 days and IFN 5 × 10⁶ u was added daily from d2 to d5. Analysis of 5-FU plasma levels was performed over 24 hours on d1 as baseline, on d2 after the first IFN injection and on d5 after the 4th IFN application. Compared to 5-FU alone, already on d2 there was a slight, but on d5 a marked increase of 5-FU plasma levels. This PK effect may contribute to the cytostatic action of 5-FU combined with IFN, especially in patients with enhanced 5-FU catabolism. Abrogation of this effect by using a double modulation of IFN and FA must be considered as disadvantageous despite several theoretical and preclinical synergism.