Phase I trial of sulindac plus 5-fluorouracil and levamisole: potential adjuvant therapy for colon carcinoma

Epidemiological studies indicate that nonsteroidal anti-inflammatory agents may reduce colorectal cancer incidence and mortality. Moreover, sulindac has been shown to attenuate the growth and progression of colonic neoplasms in an experimental model of colon carcinoma and in patients with familial adenomatous polyposis. To determine whether sulindac (300 mg/day) would increase toxicity associated with 5-fluorouracil (5-FU) and levamisole, 15 patients with advanced colorectal cancer were treated. Median treatment duration was 3 (range, 0.6-6.0) months, and median age was 56 years (33% >/= 60 years). All patients had failed prior 5-FU-based therapy, had measurable disease, and were evaluable for toxicity. Grade III/IV granulocytopenia occurred in four patients; three patients had received prior pelvic irradiation resulting in a predisposition to myelosuppression. Two patients developed grade III anemia, and occult gastrointestinal bleeding was suspected in one. No other grade II or greater gastrointestinal or other nonhematological toxicity occurred. One patient had a partial response, 3 patients had disease stabilization, and 10 patients progressed on study. Our results indicate that sulindac does not significantly increase short-term toxicity associated with 5-FU and levamisole. To determine whether sulindac increases the efficacy of adjuvant chemotherapy, we propose a phase III randomized trial in patients with lymph node-positive colon cancer.

Screening for Colorectal Cancer

Colorectal cancer is a major cause of morbidity and mortality in the United States. Early detection of the disease at an asymptomatic stage by screening holds promise for lowering the incidence of colorectal cancer deaths, yet compliance with screening guidelines is poor. Evidence in support of the use of screening techniques for colorectal cancer is accumulating, however, and screening for this disease with fecal occult blood tests and flexible sigmoidoscopy can increase the likelihood of early detection, can decrease mortality and morbidity, and can be cost effective.

Randomized phase III study of 5-fluorouracil plus high dose folinic acid versus 5-fluorouracil plus folinic acid plus methyl-lomustine for patients with advanced colorectal cancer

BACKGROUND

Metastatic colorectal cancer is generally incurable. The most active regimen available, 5-fluorouracil (5-FU) and folinic acid (Leucovorin), produces response rates of approximately 25% to 30%. Methyl-lomustine is a nitrosourea with modest activity against colorectal cancer. A randomized trial was undertaken to evaluate the impact the addition of methyl-lomustine would have on response, duration of survival, and survival rates in patients with advanced colorectal cancer.

METHODS

The methyl-lomustine/5-FU/Leucovorin (MFL) regimen consisted of methyl-lomustine (110 mg/m2), administered on Day 1 of each 8-week cycle with six weekly boluses of 5-FU (600 mg/m2), and Leucovorin (500 mg/m2). The FL treatment arm consisted of the administration of 5-FU and Leucovorin as described above. Patients were evaluated for response and toxicity after each 8-week cycle.

RESULTS

Of 319 patients included in this trial, 297 (93.1%) had disease evaluable for response and toxicity: 145 received MFL, and 152 received FL. In this trial, 526 courses of MFL and 529 courses of FL were administered. Methyl-lomustine/5-FU/Leucovorin treatment resulted in 4 complete and 30 partial responses (response rate, 21.9%), and FL treatment resulted in 9 complete and 33 partial responses (response rate, 26.4%). There was no significant difference in median survival duration between patients in the two arms (MFL = 48 weeks, FL = 51 weeks). However, MFL was significantly more toxic with greater myelosuppression than was FL (Grade 3-4 neutropenia: MFL = 56 patients, FL = 27 patients, P < 0.001; Grade 3-4 thrombocytopenia: MFL = 49 patients, FL = 2 patients, P < 0.001; Grade 3-4 anemia: MFL = 15 patients, FL = 6 patients, P < 0.001; and more prolonged median duration of granulocytopenia: MFL = 9 days, FL = 7 days, P < 0.001; and thrombocytopenia: MFL = 14 days, FL = 7.5 days, P < 0.001).

CONCLUSION

Because the addition of methyl-lomustine in the MFL schedule markedly increased the toxicity of the regimen and because the FL regimen was as effective as MFL, the authors recommend that Leucovorin and 5-FU remain the treatment choice for treating patients with metastatic colorectal cancer.

Cisplatin, 5-Fluorouracil, and leucovorin in the therapy of adenocarcinomas of the pancreas

Pancreatic cancer is resistant to most chemotherapeutic regimens. Based upon evidence of synergy between 5-fluorouracil (5-FU) and cisplatin (CDDP), and of enhanced 5-FU activity in the presence of leucovorin in other neoplasms, a phase II study of CDDP, 5-FU, and leucovorin was conducted to determine the efficacy of this regimen in patients with unresectable adenocarcinomas of the pancreas. Nineteen patients were enrolled, and all were evaluable for toxicity and response. One complete and two partial responses were observed (15.8%). Adverse effects were reversible and tolerable. This regimen has limited activity against pancreatic cancer, and cannot be recommended as standard therapy in this disease.

Phase II trial of isotretinoin and recombinant interferon alfa-2a in metastatic colorectal carcinoma

Phase II trials of the novel biologic combination isotretinoin (13-cis-retinoic aid) plus recombinant interferon alfa-2a have demonstrated this combination's major activity against advanced squamous cell carcinoma of the skin and cervix. Because this combination has had limited study in other tumors, we initiated a phase II trial of this regimen in patients with metastatic colorectal adenocarcinoma. Sixteen patients with measurable metastatic colon carcinoma who had received no previous chemotherapy were entered on the trial. Patients received recombinant interferon alfa-2a, 6 million units a day subcutaneously, and isotretinoin, 1 mg/kg per day orally in two divided doses. Patients were evaluated for response after 8 weeks of treatment and then continued on therapy until progressive disease was documented. We did not observe complete or partial responses. Two patients experienced minor responses in measurable pulmonary metastases lasting 12 and 8 weeks. Grade 3-4 toxic reactions included fatigue (5 patients), granulocytopenia (6 patients), neurotoxicity (2 patients), and elevated serum triglyceride levels (2 patients). Although this combination has demonstrated significant activity in squamous cell carcinomas of the skin and cervix, our results suggest that it has little therapeutic activity against advanced colorectal adenocarcinomas.

Aspirin and other nonsteroidal anti-inflammatory drugs and risk of colorectal adenomatous polyps among endoscoped individuals

Most epidemiological evidence supports the inverse association between use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) and colorectal cancer. Few studies have investigated the relation between use of aspirin and other NSAIDs and adenomatous polyps, which are recognized as precursors of colorectal cancer. We examined the association of adenomatous polyps and the dose and duration of use of aspirin and other NSAIDs in a case-control study of dietary risk factors for colorectal adenomatous polyps. The study population comprised 157 case and 480 control individuals who underwent an endoscopy at collaborating gastroenterology clinics in Houston, TX. Face-to-face interviews were conducted to obtain risk factor data that included information on frequency and duration of use of aspirin and other NSAIDs. Compared to the nonusers, the multivariate odds ratios for individuals who took aspirin and other NSAIDs on a weekly basis and for those who took these once/day or more were 0.77 (95% confidence interval, 0.39-1.55) and 0.36 (95% confidence interval, 0.20-0.63), respectively. Compared to the nonusers, the odds ratio for individuals who used aspirin and other NSAIDs for <5 years was 0.39 (95% confidence interval, 0.39-1.55) and 0.36 (95% confidence interval, 0.20-0.71), and for those who used these for 5 years or more, the odds ratio was 0.60 (95% confidence interval, 0.32-1.14). The results of this study suggest that aspirin and other NSAIDs are associated with a decreased risk for adenomatous polyps. Limited dose-response analyses found that the point estimate decreased with the frequency but not the duration of use of aspirin and other NSAIDs.

Preoperative infusional chemoradiation therapy for stage T3 rectal cancer

PURPOSE

To evaluate preoperative infusional chemoradiation for patients with operable rectal cancer.

METHODS AND MATERIALS

Preoperative chemoradiation therapy using infusional 5-fluorouracil (5-FU), (300 mg/m2/day) together with daily irradiation (45 Gy/25 fractions/5 weeks) was administered to 77 patients with clinically Stage T3 rectal cancer. Endoscopic ultrasound confirmed the digital rectal exam in 63 patients. Surgery was performed approximately 6 weeks after the completion of chemoradiation therapy and included 25 abdominoperineal resections and 52 anal-sphincter-preserving procedures.

RESULTS

Posttreatment tumor stages were T1-2, N0 in 35%, T3 N0 in 25%, and T1-3, N1 in 11%; 29% had no evidence of tumor. Local tumor control after chemoradiation was seen in 96% (74 out of 77); 2 patients had recurrent disease at the anastomosis site and were treated successfully with abdominoperineal resection. Overall, pelvic control was obtained in 99% (76 out of 77). The survival after chemoradiation was higher in patients without node involvement than in those having node involvement (p = n.s.). More patients with pathologic complete responses or only microscopic foci survived than did patients who had gross residual tumor (p = 0.07). The actuarial survival rate was 83% at 3 years; the median follow-up was 27 months, with a range of 3 to 68 months. Acute, perioperative, and late complications were not more numerous or more severe with chemoradiation therapy than with traditional radiation therapy (XRT) alone.

CONCLUSIONS

Excellent treatment response allowed two-thirds of the patients to have an anal-sphincter-sparing procedure. Gross residual disease in the resected specimen indicates a poor prognosis, and therapies specifically targeting these patients may improve survival further.

The role of dietary factors and chemoprevention in gastrointestinal malignancy

Environmental factors, particularly pertaining to the diet, are of importance in the pathogenesis of gastrointestinal neoplasia. Increasingly sophisticated studies have begun to elucidate some of the mechanisms responsible for both the deleterious and protective effects of compounds ingested or smoked (such as tobacco). The new and developing field of chemoprevention holds great promise for the possibility of averting neoplasia by interfering with the metabolism of carcinogens, reducing their binding to the target cell, or even by suppressing the initiated cell.

Consensus statement: octreotide dose titration in secretory diarrhea. Diarrhea Management Consensus Development Panel

Octreotide is an effective therapeutic option in controlling secretory diarrhea of varied etiology. However, marked patient-to-patient differences in the antidiarrheal effects necessitate titration of octreotide dose in individual patients to achieve optimal symptom control. A consensus development panel established guidelines for octreotide dose titration in patients with secretory diarrhea. Overall, the panel recommended an aggressive approach in selecting the initial octreotide dose and in making subsequent dose escalations in patients with secretory diarrhea due to gastrointestinal tumors (eg, carcinoids, VIPomas), AIDS, dumping syndrome, short bowel syndrome, radiotherapy, or chemotherapy. To avoid hypoglycemia in patients with diabetes mellitus-associated secretory diarrhea, the panel recommended a low initial octreotide dose and a conservative titration regimen with close monitoring a blood glucose levels. The end point of therapy should focus on a reduction in diarrhea (frequency of bowel movements or stool volume) rather than normalization of hormonal profile. Overall, octreotide is well tolerated; principal side effects are transient injection site pain and gastrointestinal discomfort. For many patients with secretory diarrhea, octreotide therapy is expected to improve the overall health and quality of life and in the long run will lessen health care costs.

Hypericin as an inactivator of infectious viruses in blood components

BACKGROUND

Hypericin is a potent virucidal agent with activity against a broad range of enveloped viruses and retroviruses. The effective virucidal activity emanates from a combination of photodynamic and lipophilic properties. Hypericin binds cell membranes (and, by inference, virus membranes) and crosslinks virus capsid proteins. This action results in a loss of infectivity and an inability to retrieve the reverse transcriptase enzymatic activity from the virion.

STUDY DESIGN AND METHODS

Since hypericin is devoid of adverse action in most blood components and blood analyses, it is investigated as an additive with potential to inactivate infective viruses in blood components intended for transfusion.

RESULTS

Complete inactivation of 10(6) tissue culture-infective doses of human immunodeficiency virus was obtained in whole blood and in diluted packed red cells after illumination with fluorescent light for 1 hour. Loss of viral infectivity to cultured CEM cells has been monitored by use of a detection assay for human immunodeficiency virus p55 in enzyme-linked immunosorbent assay and cytopathic assays. In physiologic media, hypericin interacts with albumin and lipoproteins, retaining the virucidal activity in bound form. The molecule is negatively charged and forms organic and inorganic monobasic salts (ion pairs) in physiologic pH. Various ion pairs differ in virucidal efficacy.

CONCLUSION

The apparent transfusibility of hypericin, taken together with the efficacy of the virucidal activity, the broad range of enveloped viruses affected, and the absence of adverse effects on stored red cells, may render hypericin useful for inactivation of infectious viruses in red cells.

Cancers of the stomach and the duodenum

Gastric cancer remains the seventh most common cause of cancer death in the United States, and it is the most prevalent in populous areas, such as south China, Japan, and Korea. Duodenal cancers are rare; adenocarcinomas are the most common variety. We examine recent findings concerning pathogenesis, diagnosis, and management of gastric and duodenal malignancies.

Cigarette smoking and spontaneous abortion of known karyotype. Precise data but uncertain inferences

Data from the first phase (1974-1979) of this New York City case-control study showed that 1) cigarette smoking during pregnancy was associated positively with chromosomally normal spontaneous abortion and 2) both past and current smoking were associated inversely with trisomic loss in women under age 30 years and positively in older women. The authors used data from two subsequent study phases (1979-1982 and 1982-1986) to test the stability of these associations over time and the homogeneity between payment groups (private vs. public). Spontaneous abortions (cases) were classified as chromosomally normal (n = 1,388), trisomic (n = 557), or other chromosomally aberrant (n = 409). Controls (n = 4,165) were women who had registered for prenatal care before 22 weeks' gestation and delivered at 28 weeks or later. For chromosomally normal loss, later data gave modest support to prior observations. In the total sample, current smoking (defined as smoking during the month of the last menstrual period) of 14 or more cigarettes per day was increased among chromosomally normal cases in comparison with controls (adjusted odds ratio (OR) = 1.3, 95% confidence interval (CI) 1.1-1.7) and in comparison with other aberrant cases (adjusted OR = 1.2, 95% CI 0.8-1.8). Stronger associations in public patients than in private patients (adjusted odds ratios of 1.4-1.5 versus 0.8-0.9, respectively) might indicate either a mediating effect of social disadvantage or a chance fluctuation. For trisomic loss, later data did not support prior observations. Associations between trisomy and past or current smoking did not vary significantly with age in either payment group; assuming no effect modification of age, adjusted odds ratios for smoking in relation to trisomy were 0.9-1.0.

Cigarette smoking and alcohol consumption as risk factors for colorectal adenomatous polyps

BACKGROUND

Results of epidemiologic studies suggest that there is limited evidence for the association between cigarette smoking and risk of colorectal cancer. Cigarette smoking has been shown to increase the risk of colorectal adenomatous polyps, which are recognized as precursors of colorectal cancer, while few studies have examined the association between alcohol consumption and the development of adenomatous polyps.

PURPOSE

We examined the association between cigarette smoking, alcohol consumption, and the presence of colorectal adenomatous polyps.

METHODS

Analyses were based on data from a case-control study of dietary and other lifestyle factors for colorectal adenomatous polyps. We assessed the risk of adenomatous polyps associated with total number of years of smoking, number of cigarettes smoked per day, and pack-years of smoking for past and current smokers separately. We also assessed the joint association between cigarette smoking and alcohol consumption on the risk of adenomatous polyps.

RESULTS

Current smokers who smoked more than 20 pack-years were at significantly higher risk of adenomatous polyps compared with never smokers (odds ratio [OR] = 2.56; 95% confidence interval [CI] = 1.28-5.14). Past smokers also had an increased risk of having adenomatous polyps, but no clear trend was observed for pack-years of smoking. Alcohol consumption was positively associated with risk of adenomatous polyps. Compared with nondrinkers, the strongest risk was observed for individuals who consumed 2.31-9.46 g alcohol per day (OR = 2.23; 95% CI = 1.29-3.83), and a decrease in risk was observed for individuals who consumed 9.47-67.36 g alcohol per day (OR = 1.63; 95% CI = 0.92-2.88). Among current smokers, a joint effect was observed for individuals who smoked and drank compared with those who never smoked and were not current drinkers (OR = 4.21; 95% CI = 1.88-9.41). For past smokers, a significant joint effect of smoking and current alcohol consumption was also observed, but the risk was not as strong as that for current smokers (OR = 2.61; 95% CI = 1.40-4.87).

CONCLUSIONS

These data provide further evidence of the positive association between cigarette smoking and the development of colorectal adenomatous polyps. The combination of cigarette smoking and alcohol consumption increased the risk of adenomatous polyps.

IMPLICATIONS

Future research should focus on the understanding of the role of cigarette smoking and alcohol consumption as these two factors relate to the evolution of colorectal adenomatous polyps and subsequent carcinogenesis.

bcl-2 and p53 oncoprotein expression during colorectal tumorigenesis

Apoptosis or programmed cell death represents a mechanism by which cells possessing DNA damage can be deleted. The bcl-2 proto-oncogene is a known inhibitor of apoptosis that may allow the accumulation and propagation of cells containing genetic alterations. To determine if and when the bcl-2 gene is activated during colorectal tumorigenesis and its relationship to p53, we analyzed normal mucosa, hyperplastic and dysplastic epithelial polyps, and carcinomas for the expression of these markers using immunohistochemistry. Whereas bcl-2 staining was restricted to basal epithelial cells in normal and hyperplastic mucosa, bcl-2 expression was detected in parabasal and superficial regions in dysplastic polyps and carcinomas. An inverse correlation was found between bcl-2 and p53 expression in adenomas, suggesting that these markers may regulate a common cell death pathway. Furthermore, carcinomas with a high percentage of bcl-2-positive cells were significantly more likely to have low rates of spontaneous apoptosis, as determined histologically, than those cancers with low or absent bcl-2 expression. Abnormal activation of the bcl-2 gene appears to be an early event in colorectal tumorigenesis that can inhibit apoptosis in vivo and may facilitate tumor progression.

Contrast sensitivity in dyslexia

Contrast sensitivity was determined for dyslexic and normal readers. When testing with temporally ramped (i.e. stimuli with gradual temporal onsets and offsets) gratings of 0.6, 4.0, and 12.0 cycles/deg, we found no difference in contrast sensitivity between dyslexic readers and controls. Using 12.0 cycles/deg gratings with transient (i.e. abrupt) onsets and offsets, we found that dyslexic individuals had, compared to controls, markedly inferior contrast sensitivity at the shortest stimulus durations (i.e. 17, 34, and 102 ms). This deficit may reflect more sluggish temporal summation. There was no difference in sensitivity to 0.6 cycles/deg gratings with transient onsets and offsets. Under these conditions, the two groups showed a consistent and equal increase in sensitivity relative to the ramped baseline condition at 0.6 cycles/deg at the longer stimulus durations. This demonstrates that dyslexic readers have no deficit in their ability to detect stimulus transients, a finding which appears to be inconsistent with a transient system deficit. That detection of the low-frequency stimuli was mediated by the transient system is further indicated by the fact that these stimuli were more susceptible to forward masking than were the high-frequency stimuli. The effects of masking of both high and low spatial-frequency stimuli were about equal for dyslexic readers and controls. This is not in agreement with the transient system deficit theory, according to which one would expect there to be less masking of high spatial-frequency stimuli in the case of dyslexic readers.

Clinical pharmacology and tissue disposition studies of 131I-labeled anticolorectal carcinoma human monoclonal antibody LiCO 16.88

Antibody LiCO 16.88 is a human IgM recognizing a 30- to 45-kDa intracytoplasmic antigen present in human adenocarcinoma cells. An 8-mg sample of antibody labeled with 5 mCi 131I was co-administered i.v. with 120 mg (three patients), 240 mg (three patients) or 480 mg (four patients) unlabeled antibody as a 4-h infusion. The plasma half-life was 24 +/- 1.2 h and the immediate apparent volume of distribution was 5.2 +/- 0.2 l at the 28-mg dose level. The plasma half-lives and the cumulative urinary excretion of radiolabel did not seem to vary significantly with increasing doses of unlabeled antibody. However, both the volume of distribution and the clearance rate from plasma increased significantly with increasing antibody dose. Uptake of antibody into tumor tissues obtained during laparotomy 8-9 days after administration varied between 0.00002% ID/g and 0.00127% ID/g. In five of seven patients, the tumor content of antibody was higher than that in adjacent normal tissue. Tumor-to-normal tissue ratios ranged from 0.8 to 10 (mean = 3.8 +/- 1.0). In general, the higher radioactivity(cpm)/g tumor was confirmed by both immunoperoxidase and autoradiography. Antibody 16.88 localizes in tumors after administration and may be considered for use in radioimmunotherapy trials.

Nonsteroidal antiinflammatory drugs and human cancer. Report of an interdisciplinary research workshop

BACKGROUND

Since the 1970s, work in several disciplines (toxicology, pharmacology, clinical medicine, epidemiology) increasingly has suggested that aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) may reduce the occurrence or progression of colorectal cancers and polyps and perhaps of other gastrointestinal tumors. The potential application of these findings for chemoprevention of such cancers in man now deserves serious consideration.

METHODS

An interdisciplinary workshop was held by the American Cancer Society in March 1994 to review the current knowledge of NSAIDs and cancer and to seek a consensus on future research directions, particularly concerning the possibility of randomized prevention trials in human populations.

RESULTS

A wide-ranging review was conducted of past and current research regarding (1) NSAIDs' effects in experimental animal cancer models; (2) clinic experience in NSAID treatment, particularly in familial polyposis; (3) pharmacologic studies regarding the enzymatic and metabolic actions of NSAIDs; and (4) epidemiologic observations on the relationship of aspirin/NSAID usage to colorectal cancer occurrence in human populations.

CONCLUSIONS

Combined evidence from different research disciplines strongly supports the notion that aspirin and other NSAIDs act to prevent the development or progression of certain human gastrointestinal cancers, especially colorectal cancer. Consequently, the workshop recommended that randomized prevention trials be undertaken. For various logistic reasons, such trials probably should focus on NSAID effects on the occurrence and progression of colorectal polyps rather than on carcinoma itself. Continued research also is needed to clarify further the pharmacologic, clinical, and epidemiologic nature of NSAIDs' influences on human carcinogenesis.

Neurobiologic considerations in early surgery for epilepsy

Children with well-localized medically resistant seizures are often referred for surgical therapy. In young children, at least three maturational issues play a significant role in the selection process and long-term outcome. First, the early years are a time of exceptionally rapid brain development leading to dynamic changes in the electroencephalogram and the clinical expression of seizures. Many early-onset seizure presentations are also associated with catastrophic outcomes, developmental arrest, or regression. Second, the immature limbic system may be vulnerable to stresses operating in early life, although the consequences may not become apparent for many years. Third, in comparison to the adult, the child's nervous system typically exhibits superior functional recovery after lesioning, but the process of sparing and recovery is often incomplete. An understanding of how these neurobiologic factors influence developmental outcome will ultimately lead to greater selectivity of candidates for early surgery and to improved long-term prognosis.

Phase II trial of edatrexate in patients with advanced hepatocellular carcinoma

BACKGROUND

The methotrexate analogue edatrexate (10-ethyl-10-deaza-aminopterin, or 10-EDAM) has demonstrated greater activity than methotrexate has against murine tumors and human tumor xenografts. Phase II trials of edatrexate have already demonstrated its activity against breast, lung, and head and neck carcinomas. A phase II trial of edatrexate was conducted in patients with advanced hepatocellular carcinoma.

PATIENTS AND METHODS

Seventeen patients with previously untreated unresectable hepatocellular carcinoma were enrolled on the study. Edatrexate, 80 mg/m2 weekly for 5 weeks, was administered intravenously. The treatment course was repeated every 6 weeks. Tumor response was evaluated by computerized tomographic scan after 2 courses.

RESULTS

No complete or partial responses were observed in this trial. Two minor responses, each lasting less than 12 weeks, were observed. Twelve patients had elevated serum alpha-fetoprotein (AFP) levels at entry into the study; 4 of the 12 patients experienced a > or = 25% decrease in the level of this tumor marker; 3 of the 4 had a > 50% reduction in AFP level. Grade 3 and 4 toxic effects were granulocytopenia, thrombocytopenia, anemia, oral mucositis, skin reactions, fatigue, anorexia, and diarrhea.

CONCLUSIONS

Edatrexate administered at this dose and schedule appears to have little therapeutic efficacy against advanced hepatocellular carcinoma.

Evidence that protein kinase C-alpha activation is a critical event in phorbol ester-induced multiple drug resistance in human colon cancer cells

We previously designed and characterized an in vitro model of the intrinsic drug resistance of human colon cancer. The human colonic epithelium is chronically exposed to endogenous protein kinase C (PKC) stimulatory factors, and our model demonstrated that activation of PKC induces resistance to multiple anticancer drugs in the metastatic human colon cancer cell line KM12L4a. PKC is an isozyme family with ten members, eight of which are phorbol ester-responsive. In this report, we show that thymeleatoxin (Tx), a daphnane tumor promoter that selectively activates the phorbol ester-responsive isozymes cPKC-alpha, -beta 1, -beta 2, and -gamma, was just as effective in inducing drug resistance in KM12L4a cells as phorbol dibutyrate, a potent activator of all phorbol ester-responsive PKC isozymes. The induction of resistance by Tx was associated with a reduction in cytotoxic drug accumulation in KM12L4a cells. We demonstrated by immunoblot analysis and hydroxylapatite chromatography that KM12L4a cells express active cPKC-alpha but not cPKC-beta 1, -beta 2, or gamma. Our results provide strong evidence that phorbol-ester activation of cPKC-alpha is sufficient for the induction of resistance observed in KM12L4a cells. The possibility that endogenous PKC activators may induce intrinsic drug resistance in clinical colon cancer by an analogous mechanism is strongly suggested by our detection of active cPKC-alpha in surgical specimens of human colon carcinomas.

Phase II trial of docetaxel (Taxotere) in metastatic colorectal carcinoma

BACKGROUND

Docetaxel (Taxotere) is prepared from a noncytotoxic precursor extracted from the needles of the Taxus baccata. Preclinical investigations have demonstrated that docetaxel is very active in colon adenocarcinoma murine models. Phase I studies revealed granulocytopenia to be the dose-limiting toxicity. Initial clinical trials also demonstrated docetaxel's activity in ovarian, breast, and non-small cell lung cancer. Because of this encouraging preclinical and clinical activity, we initiated a phase II study of docetaxel in patients with metastatic colorectal carcinoma.

PATIENTS AND METHODS

Docetaxel, 100 mg/m2, was administered as a 1-hour intravenous infusion every 21 days. Nineteen patients were entered on the trial. All patients had measurable disease and had not received prior chemotherapy for metastatic disease.

RESULTS

No complete or partial responses were observed. Granulocytopenia was the dose-limiting toxic effect. Seventeen patients had grade 4 granulocytopenia; 8 of these patients received antibiotics for neutropenic fevers. Twelve patients experienced hypersensitivity reactions, and 15 patients experienced cutaneous toxic reactions. One patient demonstrated evidence of fluid retention.

CONCLUSIONS

Administered at the stated dose and schedule, docetaxel has little activity against metastatic colorectal carcinomas. The toxicity profile, consisting of granulocytopenia, hypersensitivity reactions, cutaneous reactions, and edema, has been previously described in patients receiving docetaxel.