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Fatigue is a common side effect of interferon (IFN) therapy, reported in 70-100% of patients treated with IFN. The etiology of IFN-mediated fatigue (IMF) is multifactorial, with endocrine failure, neuropsychiatric disturbance, autoimmunity, and cytokine dysregulation potentially being contributors. Thyroid dysfunction, associated with the development of autoantibodies, is seen in 8-20% of patients receiving IFN-alpha. IFN-alpha also suppresses the hypothalamic-pituitary-adrenal axis. In addition, IFN-alpha therapy leads to depression and cognitive slowing, and depressed patients are predisposed to develop fatigue. Clinical management of IMF is challenging because the syndrome is variable in onset and severity and the pathophysiology is poorly understood. Current management typically centers on dose reduction, but ancillary nonpharmacologic measures may help improve symptoms. Other strategies include antidepressant or anxiolytic therapy and treatment of coexisting hypothyroidism. Future studies utilizing IFN should include quantitative guidelines for grading and managing IMF., (Copyright 2001 American Cancer Society.)

Purpose: To investigate mechanism-directed regimens in maximizing the efficacy of fluorouracil (5-FU) in advanced colorected cancer., Patients and Methods: Based on promising phase II data, a randomized comparison of various methods for the biochemical modulation of 5-FU was undertaken in patients with advanced colorectal cancer. The control group received single-agent 5-FU as a 24-hour infusion weekly. Patients (N = 1,120) with no prior chemotherapy for metastatic disease were randomized to one of the following arms: arm A, 5-FU 2,600 mg/m2 by 24-hour infusion, weekly; arm B, N-phosphonoacetyl-l-aspartic acid 250 mg/m2 day l, 5-FU 2,600 mg/m2 by 24-hour infusion day 2, weekly; arm C, 5-FU 600 mg/m2 with oral leucovorin (LV) 125 mg/m2 hourly for the preceding 4 hours, weekly; arm D, 5-FU 600 mg/m2 with intravenous (IV) LV 600 mg/m2, weekly; arm E, 5-FU 750 mg/m2/d IV by continuous infusion for 5 days, then 750 mg/m2 weekly, and recombinant interferon alfa-2a 9 million units subcutaneously three times weekly. Median follow-up was 4.8 years., Results: Of the 1,098 assessable patients, 57% had measurable disease. The toxicity of all the regimens was tolerable. Grade 4 or worse toxicity occurred in 11%, 11%, 30%, 24%, and 22% on each arm, respectively; diarrhea was the most common adverse effect. These toxicity patterns favored significantly (P <.001) the 24-hour infusion arms. Median survival (months) by arm was A, 14.8; B, 11.9; C, 13.5; D, 13.6; and E, 15.2. These survival durations did not differ significantly., Conclusion: We conclude that a weekly infusion regimen of 5-FU is significantly less toxic than and as effective as 5-FU bolus regimens modulated by either LV or interferon in patients with metastatic colorectal cancer.

Interferons (IFN)-alpha, -beta, and -gamma enhance the activity of 5-fluorouracil (5-FU) in vitro and in vivo. Various mechanisms have been identified to account for this modulation. First, IFN induces the enzyme thymidine phosphorylase, thereby enhancing the conversion of 5-FU to its active metabolite, 5-fluorodeoxyuridine monophosphate (FdUMP), leading to increased depletion of thymidine triphosphate pools and increased DNA fragmentation. Second, IFN treatment leads to abrogation of an 5-FU-associated increase in the enzyme thymidylate synthase (TS), thus increasing tumor sensitivity to 5-FU. Finally, IFN augments plasma 5-FU levels. Single-institution studies of 5-FU in combination with IFN-alpha showed high response rates; however, randomized trials demonstrated equivalent survival to 5-FU alone or in combination with leucovorin (LV). Randomized trials of 5-FU double-modulated by both IFN-alpha and LV showed no response or survival advantage compared with 5-FU/LV, and greater toxicity. The randomized trials are all limited by inconsistent schedules of administration of IFN-alpha. The combination of 5-FU and IFN-beta has shown promising results in single-arm and small randomized trials. A large randomized trial, requiring a standardized schedule of administration of IFN-beta, has been initiated.

Fatigue occurs in more than 70% of patients treated with interferon-alpha (IFN-alpha) and is the most problematic toxicity associated with IFN-based immunotherapy. Abundant evidence suggests that immune-mediated endocrine disease occurs during IFN-alpha therapy, which may contribute to the etiology of fatigue. Autoimmune thyroid disease is a well-recognized consequence of IFN-alpha therapy and may be mediated by the induction of IFN-gamma production by lymphocytes. Administration of exogenous IFN-gamma has been associated with upregulation of class II major histocompatibility antigens in the thyroid and the development of thyroiditis. Interferon-alpha also stimulates the production of interleukin-6; both interleukin-6 and IFN-gamma have specific effects on thyrocyte function. There also is evidence suggesting that IFN-alpha initiates a cytokine cascade that effects the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes, thus affecting regulation of glucocorticoid and sex steroid hormone secretion, but the clinical significance of these observations has not been established. Although endocrine disease will not explain the occurrence of fatigue symptoms in all patients, there is clear evidence that hormonal deficiency syndromes occur in a relatively large portion of patients receiving systemic IFN-alpha therapy. Most importantly, the possibility of hypothyroidism must be considered; however, diagnosis of hypothyroidism in cancer patients is complicated by the occurrence of the "sick euthyroid syndrome." Clinical recommendations for assessment and treatment of IFN-alpha-induced fatigue are offered. Most importantly, measurements of thyroid-stimulating hormone and antithyroid autoantibodies should be used to evaluate thyroid status. Acknowledging the limitations of current clinical data, adrenal- and gonadal-axis dysfunction also must be considered in patients with IFN-alpha-induced fatigue.

We have used pulsed-field gel electrophoresis to examine 5-fluorouracil (5FU)-induced DNA double-strand breaks (DSBs), both with and without modulation by IFN-alpha2a (IFNalpha), in HT29 human colon adenocarcinoma cells. Although 24-h treatment with either 10 microM 5FU or 500 units/ml IFNalpha did not result in significant DNA fragmentation, the combination of 5FU + IFNalpha resulted in a significant increase in DNA DSBs versus either drug alone (P < 0.05). The pattern of fragmentation induced by treatment with 5FU + IFNalpha was compared to that induced by gamma-radiation, which generates lesions at random sites, digestion with NotI restriction endonuclease, which cleaves at the specific sequence 5' ellipsis GCGGCCGCellipsis 3', and HhaI restriction endonuclease, which cleaves at the specific sequence 5'ellipsis GCGCellipsis 3'. 5FU + IFNalpha resulted in a specific pattern characterized by the accumulation of fragments of <3 Mb in the absence of fragments of >3 Mb, which differed from that of gamma-radiation and restriction endonuclease digestion. Because neither morphological nor DNA fragmentation characteristic of apoptosis was observed after 5FU + IFNalpha treatment, the nonrandom pattern of DSBs that was observed did not appear to be the result of the initiation of programmed cell death within these cells.

The enzyme/cytokine thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) has diverse functions within cells, including the regulation of steady-state thymidine levels, the conversion of the cancer chemotherapeutic agent 5-fluorouracil (FUra) to an active metabolite, and the mediation of angiogenesis in normal and malignant cells. Although the levels of TP/PD-ECGF vary substantially among different tissues and are generally found to be elevated in tumors, little is known about the control of its expression in vivo in humans. In this study, peripheral blood mononuclear cells were obtained from patients prior to and during treatment with IFN and FUra and analyzed for TP/PD-ECGF expression. Sixteen of 21 patients (76%) exhibited an average 3-4-fold increase of TP/PD-ECGF protein levels after treatment with either IFN-alpha or-beta, with the remaining patients having either a decrease (four patients) or no change (one patient) at the sampling times examined. Expression in vivo increased rapidly within 1-2 h of IFN treatment and remained elevated for up to 48 h after its administration. The increase in TP/PD-ECGF protein was accompanied by a concomitant increase in TP/PD-ECGF mRNA levels. TP/PD-ECGF mRNA expression in cells in vitro was induced by IFN but not by pharmacologically relevant concentrations of FUra, suggesting that the IFN was responsible for the induction seen in the patients. This study demonstrates that IFN induces TP/PD-ECGF expression in vivo by regulation of the level of mRNA expression.

Evidence suggests that interferon-alpha (IFN-alpha) augments the antineoplastic activity of 5-fluorouracil (5-FU) in human adenocarcinoma cell lines in vitro and may enhance the efficacy of 5-FU in patients with advanced colorectal carcinoma. In addition, 5-FU may be more effective when given as a prolonged, continuous i.v. infusion (PCI). The Eastern Cooperative Oncology Group performed a Phase II trial of PCI 5-FU plus IFN-alpha in patients with advanced pancreatic carcinoma. Twenty-six patients with advanced, surgically incurable adenocarcinoma of the pancreas received PCI 5-FU (250 mg/m2 daily for 28 days) in combination with IFN-alpha (5 x 10(6) IU/m2 s.c. thrice weekly). Treatment cycles were repeated 14 days or longer after completion of the previous cycle. Treatment was interrupted prior to day 28 if intolerable toxicity developed, and the dose of 5-FU was reduced in subsequent cycles. Partial response occurred in two of 24 evaluable patients (8%; 95% confidence interval, 0-19%). The majority of the study group (88%) had liver metastases. Patients whose serum lactate dehydrogenase (LDH) was more than twofold elevated developed 5-FU-related toxicity significantly sooner than patients with smaller elevations in serum LDH (9 vs. 22 days; p = 0.003). A similar trend was observed for patients with a more than twofold elevation in serum glutamic-oxaloacetic transaminase (SGOT; 9 vs. 15 days; p = 0.07). In conclusion, PCI 5-FU plus IFN-alpha has minimal activity in patients with advanced pancreatic carcinoma, and elevated serum LDH and/or SGOT may be useful for predicting greater toxicity from 5-FU-based therapy in patients with liver metastases.

The effects of prolonged exposure to the ribonucleotide reductase (RR) inhibitor, hydroxyurea (HU), were assessed in the presence or absence of recombinant interferon alfa-2a (IFN) in wild-type human colon cancer cells (HT-29) and variants expressing low-level resistance to HU (R200). IFN at nontoxic concentrations decreased the IC50 of HU from 368 microM to 215 microM (P < 0.01) in wild-type cells, but not in the resistant variants. Potential cellular targets for the HU/IFN interaction were examined. In wild-type, but not resistant cells, treatment with HU at clinically achievable concentrations (1000 microM) resulted in rapid early inhibition of RR activity between 4 and 24 h after treatment with a maximal decrease of 65% at 12 h, decreases in cellular levels of dATP, dCTP and dGTP by 50-90% over the same time course, and a two- to fourfold increase in the level of mRNA for both the M1 and M2 subunits of RR, at 24, but not between 1 and 4 h, which probably represents a response to the earlier decrease in RR activity. IFN at a clinically achievable concentration (500 U/ml) failed to augment the effects of HU on RR protein, RR mRNA levels or RR enzyme activity in either the wild-type or resistant cells, suggesting that the mechanism by which IFN augments the effects of HU in the wild-type cells is independent of the effects of HU on M2.

Human papillomavirus (HPV) is associated with 65-95% of in situ or early invasive squamous cell carcinomas of the cervix. A multiinstitutional, prospective phase II clinical trial was initiated by the Eastern Cooperative Oncology Group (ECOG) to study the activity of IFN-alpha 2b in women with metastatic or locally recurrent cervix cancer. The activity of IFN-alpha 2b was correlated with the presence of HPV as measured by Southern blot hybridization or polymerase chain reaction techniques in 17 patients. All patients had failed prior definitive therapy with surgery, radiation, and chemotherapy. IFN-alpha 2b was administered at 10 MU/m2 subcutaneously three times per week. Among 31 patients enrolled, 3 achieved a clinical response to treatment. Tumor was accessible for biopsy in 17 patients. The presence of HPV was assayed by Southern blot hybridization (2 of 17) and/or polymerase chain reaction (PCR) technology (15 of 17). Of the 17 assays, 16 were informative. HPV was detected in 5 of 16 patients. Of 5 HPV-positive women, 2 responded to treatment, versus 1 of 11 HPV-negative women, thus not permitting reliable statistical analysis. It is concluded that IFN-alpha 2b has only minimal activity against advanced, recurrent cervical cancer.

Clinical studies have demonstrated that the combination of 5-fluorouracil (FUra) and IFN-alpha has activity in the treatment of advanced colorectal cancer. Treatment of human colon carcinoma cells with IFN caused a 5-fold increase in the level of thymidine phosphorylase (TP) mRNA and an 8-fold increase in TP enzyme activity. Since TP catalyzes the first step in the direct conversion of FUra to deoxyribonucleotides, its induction by IFN is a potential biochemical mechanism for the modulation of the antitumor activity of FUra. In contrast to the activity measured in cell extracts, however, thymine utilization by intact cells was increased less than 2-fold by IFN, suggesting that the metabolic activation of FUra by TP in the IFN-treated cells was similarly suboptimal. This was likely due to a rate-limiting amount of cosubstrate for TP, and in this study, a series of 5-substituted 2'-deoxyuridine analogues were synthesized and tested as potential deoxyribose donors for TP. One of the compounds, the novel pyrimidine analogue 5-ethoxy-2'-deoxyuridine (EOdU), was found to be a substrate for the transferase reaction of TP, to have little or no direct cytotoxicity, to selectively increase the cellular levels of 5-fluoro-dUMP, to enhance the inhibitory effect of FUra on thymidylate synthase activity, and to potentiate the cytotoxicity of FUra and IFN in human colon carcinoma cells. EOdU was tested in vivo against HT-29 cells grown as xenografts in nude mice. The combination of EOdU+FUra+IFN-alpha 2a produced tumor regressions and a significantly greater delay in tumor growth when compared to FUra+IFN-alpha 2a, FUra+EOdU, or FUra or IFN used alone; tumors were 72% smaller in the EOdU+FUra+IFN-alpha 2a-treated animals compared to the saline control group. A comparable antitumor effect was also found when a related nucleoside analogue, 5-propynyloxy-2'-deoxyuridine, was used with FUra+IFN, and it also showed modulating activity when used with only FUra. The antitumor activity of the three agent combination (nucleoside+IFN+FUra) was comparable to that of a higher dose of FUra used alone, but it was substantially less toxic to the animals than the higher dose of FUra, indicating that the modulating agents improved the therapeutic index of FUra.(ABSTRACT TRUNCATED AT 400 WORDS)

alpha-Interferon (IFN-alpha) enhances the activity of 5-fluorouracil in patients with advanced colorectal carcinoma. Preclinical evidence suggests a similar potential role for IFN-alpha combined with cyclophosphamide, doxorubicin (Adriamycin, Adria Laboratories, Columbus, OH), and 5-fluorouracil (CAF) in advanced adenocarcinoma of the breast. To determine a maximum tolerated dose of IFN-alpha that could be combined with CAF and that did not compromise CAF dose intensity and to determine the effect of IFN-alpha on the pharmacokinetics of doxorubicin, a phase I study of IFN-alpha plus CAF was performed by the Eastern Cooperative Oncology Group. Nine patients with advanced breast cancer received CAF (cyclophosphamide at 100 mg/m2/day p.o. on days 1-14, doxorubicin at 30 mg/m2 and 5-fluorouracil at 500 mg/m2 i.v. bolus on days 1 and 8) plus IFN-alpha (1 milliunit/m2, n = 6, or 2 milliunits/m2, n = 3) given s.c. on days 1, 3, 5, and 8 (1 h prior to the doxorubicin and 5-FU injection on days 1 and 8) of each cycle every 28 or more days. Escalation of the IFN-alpha dose occurred in cohorts of 3-6 patients if a dose-limiting toxic event (neutropenic fever, platelet nadir of < 25,000/microliters, > 2-week treatment delay, or a > 50% dose reduction in day 8 CAF) occurred during the first two cycles in 0 of 3 or 1 of 6 patients. During cycle 1, IFN-alpha was omitted on day 1, and multiple plasma samples were drawn on day 1 (without IFN-alpha) and day 8 (with IFN-alpha) after each doxorubicin injection and were analyzed for plasma doxorubicin concentration. The maximum tolerated dose of IFN-alpha by our criteria was 1 milliunit/m2, and neutropenia was the predominant toxic effect that precluded IFN-alpha dose escalation. The dose intensity of CAF achieved with IFN-alpha was identical to that for CAF alone observed in prior studies. IFN-alpha had no significant effect on the pharmacokinetics of doxorubicin, although 3 of 7 patients studied had reduced doxorubicin clearance, ranging from 32% to 69%. Alternative CAF drug delivery schedules (all drugs given i.v. every 3-4 weeks) that are more amendable to hematopoietic growth factor support may be more suitable to combine with higher doses of IFN-alpha that may produce modulation.

Background: Combinations of 5-fluorouracil (5FU) and recombinant alfa-2a-interferon (IFN) are synergistic in vitro and have demonstrated activity in colorectal carcinoma, renal cell carcinoma, and urothelial tumors., Methods: A Phase II trial of the combination of 5FU, 750 mg/m2 daily x 5 followed by weekly bolus therapy, and IFN, 9 MU subcutaneously three times per week, was initiated in patients with esophageal carcinomas. Patients were required to have biopsy-proven squamous cell or adenocarcinoma of the esophagus, locally advanced or metastatic disease beyond the scope of surgical resection, and adequate performance status, renal, hepatic, and bone marrow function., Results: Twenty-one patients were enrolled; one patient was inevaluable for response because he had received prior chemotherapy, but was evaluated for toxicity. Eleven patients had metastatic disease, and 10 had locally advanced disease. Thirteen patients had squamous cell carcinoma and 8 adenocarcinoma. Toxicities were acceptable with no serious diarrhea and only two cases of serious stomatitis, although a greater than expected incidence of neurologic toxicity was observed. There were five responders (25%) including two patients with advanced or locally advanced disease rendered pathologically free of disease. One patient, initially considered surgically unresectable, was able to undergo a total thoracic esophagectomy after responding to treatment with 5FU/IFN, at which time only a single microscopic focus of carcinoma in situ was found. She remains alive and free of disease at 18+ months. A second patient who presented with metastatic disease and nearly complete obstruction of the esophagus regained normal swallowing function after treatment with 5FU/IFN; rebiopsy of all lesions revealed the patient to be pathologically free of disease. He survived over 2 years., Conclusions: This regimen employing a single cytotoxic agent has activity in esophageal carcinoma. Strategies employing biochemical modulation deserve additional investigation in the treatment of esophageal carcinoma.

The interferons enhance the cytotoxicity of antimetabolites, alkylating agents, and plant antibiotics against cultured human tumours in vitro and in vivo. Five clinical trials in humans with advanced colorectal carcinoma have demonstrated responses ranging from 26 to 63% in patients treated with 5-fluorouracil (5-FU) plus interferon-alpha (IFN-alpha), suggesting improved response with the combination as compared with 5-FU alone. In addition, responses have been observed in patients with adenocarcinomas of the lung, pancreas, breast, and kidney, squamous cell carcinoma of the oesophagus, and urothelial carcinoma treated with 5-FU/IFN-alpha. However, enhanced 5-FU-related toxicity was observed in these studies, as has been observed when 5-FU is combined with other modulating agents, such as leucovorin. While some studies suggested that enhanced 5-FU-related toxicity was associated with an IFN-alpha-induced reduction in 5-FU clearance when 5-FU was given as an intravenous (i.v.) bolus (750 mg/m2 IV weekly) or as a high-dose five-day continuous infusion (CI) (750 mg/m2/day x 5 days), another study found enhanced 5-FU toxicity in the absence of pharmacokinetic perturbation when 5-FU was given as a low-dose prolonged CI (300 mg/m2/day x 28 or more days).(ABSTRACT TRUNCATED AT 250 WORDS)

IFNs potentiate the activity of multiple chemotherapy drugs in vitro; improved activity has been noted with 5-FU and IFN-alpha against colon carcinoma and with IFN-alpha and DTIC against melanoma. The mechanisms whereby interferon potentiates the activity of chemotherapeutic drugs are complex, and different mechanisms may be operative with different drugs and against different tumors. Both indirect immunoaugmentative effects of interferon and direct biochemical modulation of the drugs (as documented in detail with 5-FU) may play a role; further elucidation of these mechanisms will enable us to optimally utilize the combination of interferon and antineoplastic agents.

Interferon-alpha (IFN alpha) increases the cytotoxicity of 5-fluorouracil (FUra) in vitro, and the combination has clinical efficacy against advanced colorectal cancer. IFN alpha treatment of HT-29 colon carcinoma cells induced a greater than two-fold increase in the intracellular levels of the active metabolite of FUra, FdUMP. Using cell extracts from HT-29 cells and FUra as substrate, IFN alpha produced a 1.9- and 8.7-fold increase, respectively, in the activities of uridine phosphorylase and pyrimidine nucleoside phosphorylase (PyNP). Furthermore, the effect was selective for the conversion of FUra to FdUMP, as IFN alpha did not increase the cellular levels of FUTP, nor did it change the extent of incorporation of FUra into RNA (or DNA). IFN alpha also had no effect on thymidine kinase activity, the second step in the activation of FUra. Hence the effect of IFN alpha on PyNP activity is likely a critical biochemical event that modulates the cytotoxicity of FUra.

We have previously shown that the combination of 5-fluorouracil (5-FUra) and recombinant alpha-2a-interferon (rIFN-alpha-2a) produced objective responses in 23 of 32 (63%) previously untreated patients with advanced colorectal carcinoma. Because in vitro data suggest that rIFN-alpha-2a modulates the cytotoxic effects of 5FUra in a concentration-dependent manner, a phase I clinical trial was initiated to determine the maximum tolerated dose of rIFN-alpha 2a when administered in combination with 5FUra. A total of 27 patients with advanced colorectal carcinoma were enrolled. The median age was 64 years, and the median performance status was 1. A total of 18 patients had no prior chemotherapy and 19 no prior 5FUra. 5FUra was administered at 750 mg/m2/day by continuous i.v. infusion for 5 days, followed by weekly bolus therapy. rIFN-alpha 2a was administered at 6, 9, 12, 15, or 18 x 10(6) units s.c. beginning on day 1. The dose-limiting toxicity of this regimen was fatigue, resulting in a decrease in performance status, and this was the only toxicity that correlated with increasing dose of rIFN-alpha 2a. Eastern Cooperative Oncology Group grade 3-4 toxicities included leukopenia (6), thrombocytopenia (2), anemia (4), stomatitis (4), diarrhea (4), neurological (2), infection (2), and allergy (2). Three quarters of the patients required interruption of therapy or dose reductions of either 5FUra or rIFN-alpha 2a for toxicity. Among the patients with measurable disease who were previously untreated with 5FUra, 5 of 9 at the lowest dose levels achieved an objective response, including one pathological complete responder, whereas 0 of 9 at the three highest dose levels responded. Among patients previously treated with 5FUra, only 1 achieved an objective response. We conclude that the maximum tolerated dose of rIFN-alpha 2a, when administered with 5FUra as above, is 15-18 x 10(6) units; however, the efficacy of this regimen does not appear to be related to the dose intensity of rIFN-alpha 2a, and future regimens should employ a lower dose, intermittent schedule of rIFN-alpha 2a, which may be better tolerated.

Recombinant interferon alfa-2a (rIFN alpha-2a) synergistically augments the cytotoxic effects of the antimetabolite fluorouracil (5-FU) against two human colon cancer cell lines. A pilot clinical trial was initiated to determine whether this same combination of agents would show clinical utility greater than that expected with 5-FU alone in patients with advanced colorectal carcinoma. 5-FU was administered at 750 mg/m2/d for 5 days as a continuous intravenous infusion followed by weekly bolus therapy. rIFN alpha-2a was administered at 9 million units subcutaneously three times per week starting on day 1. Doses of 5-FU were modified for mucosal toxicities and myelo-suppression, and doses of rIFN alpha-2a were modified for fatigue and neurologic toxicities. Thirty-two previously untreated patients with advanced colorectal carcinoma were entered into a clinical trial. With the exception of one patient with a destructive lesion of the sacrum, all patients had metastases to visceral organs, abdominal wall, or pelvis. Twenty patients (63%) achieved a partial response, seven remained stable, and five had progressive disease. Mucosal toxicities limited delivery of full projected dose. Two patients died following episodes of watery diarrhea progressing to sepsis. A third died suddenly, secondary to an interstitial pneumonitis. The remainder of the toxicities were managed with dose reductions. At the median follow-up of 8 months, 23 of 32 patients remain alive. Nine are alive at 16 to 30+ months. The early results of this single-institution study are promising, but will require confirmation in a multi-institutional setting currently being conducted by the Eastern Cooperative Oncology Group.

Based on in vitro studies that have demonstrated synergy between recombinant alfa-2a-interferon (rIFN alpha-2a) and the fluoropyrimidine, fluorouracil (5FU), against two human colon cancer cell lines, a pilot clinical trial was initiated to determine the effects of the combination of 5FU and rIFN alpha-2a in patients with advanced, unresectable colorectal carcinoma. A total of 30 patients were enrolled; all were evaluable. 5FU was administered as a loading course, 750 mg/m2 daily for 5 days by continuous infusion followed by weekly bolus therapy, rIFN alpha-2a, 9 MU, was administered subcutaneously three times per week. Of 17 previously untreated patients evaluable for response, 13 achieved a response. Three patients had disease progression. No previously treated patients had a major response. There was one death clearly related to therapy, an event preceded by watery diarrhea and neutropenic sepsis. Other toxicities were reversible and responded to dose reduction. With a median follow-up of 16+ months, median survival has not been reached among the previously untreated patient cohort. We conclude that the combination of 5FU and rIFN alpha-2a is an active regimen against disseminated colorectal cancer in previously untreated patients.

Recombinant interferon (rIFN) modulates the cytotoxic effects of the fluorinated pyrimidine, 5-fluorouracil (5FU), in in vitro experimental tumor cell systems. In three clinical trials employing rIFN and 5FU in patients with advanced colorectal carcinoma conducted at the Albert Einstein College of Medicine, more than half the patients achieved an objective response. Of interest, the clinical spectrum of toxicities observed with this combination is different from those seen with either rIFN or 5FU alone. This novel constellation of toxicities includes a clinical syndrome characterized by watery diarrhea followed by life-threatening sepsis. Thus, careful observation and characterization of these toxicities are required. Patient education, with the goal of making patients recognize serious side effects, is important in the management of these patients.