Phase II study of taxol, merbarone, and piroxantrone in stage IV non-small-cell lung cancer: The Eastern Cooperative Oncology Group Results

New chemotherapy agents in the treatment of advanced non-small cell lung cancer: an update including data from the Seventh World Conference on Lung Cancer

Over the past two decades, modest gains have been made in chemotherapy for non-small cell lung cancer with the addition of cisplatin-based regimens to the therapeutic armamentarium. Over the last decade, several new agents with significant activity have reached the level of Phase II and III testing. This list of new drugs includes: navelbine, the taxanes--taxol and taxotere, gemcitabine, edatrexate and the camptothecins--irinotecan and topotecan. During this period, oral etoposide and epirubicin were re-investigated and biological agents such as the retinoids, interferons and interleukins were also explored as alternatives to traditional chemotherapy. As these new drug investigations proceeded, basic scientists made important discoveries which are now beginning to be applied to therapy. The future promises to combine these active new drugs with therapies directed against targets unique to non-small cell lung cancer cells.

Paclitaxel-induced neuropathy

BACKGROUND

Paclitaxel (Taxol) is a new antineoplastic agent derived from the bark of the western yew, Taxus brevifolia, with important activity against several tumors such as ovarian cancer, breast cancer, lung cancer and head and neck cancer. Because it promotes microtubule assembly, neuropathy occurs as one of its toxic side effects. Our purpose was to evaluate the incidence, severity, dose-dependency and reversibility of paclitaxel-induced neuropathy.

PATIENTS AND METHODS

We prospectively studied 27 patients treated with single-agent paclitaxel at three dose levels. Paclitaxel was administered by 3-hour intravenous infusion every three weeks in all patients, and if possible, all were evaluated neurologically before paclitaxel, after every other cycle and after discontinuation of therapy. We used a standardized questionnaire and neurologic examination with emphasis on neuropathic symptoms and signs. The severity of symptoms and signs was scored. Quantitatively, vibratory perception threshold (vibrameter) and grip strength (dynamometer) were measured.

RESULTS

Six, 14 and seven patients were treated with 135 mg/m2, 175 mg/m2 and 250-300 mg/m2, respectively. Neuropathic symptoms occurred in 50%, 79% and 100%, neuropathic signs in 83%, 86% and 100%, and dose-limiting neurotoxicity in 0%, 21% and 71% of patients, respectively. Neurotoxicity progressed with higher cumulative dose and was more pronounced with higher dose per course. Paclitaxel-induced neuropathy was predominantly sensory in character, though minor motor signs were present. Follow-up data of 12 patients after discontinuation of paclitaxel therapy showed that paclitaxel-induced neuropathy is at least partially reversible.

CONCLUSIONS

Paclitaxel-induced neuropathy is a dose-dependent phenomenon, occurring with higher cumulative dose and higher dose per cycle. Using 3-weekly 3-hour infusions of paclitaxel, dose-limiting neurotoxicity can be expected in patients treated with 250 mg/m2 or more each cycle.

New drugs in non-small cell lung cancer. An overview

Chemotherapy is rather ineffective in non-small cell lung cancer. However, in the last few years, a number of new anticancer agents have been developed which have definite activity in this disease. Among them are the taxanes and CPT-11, drugs with novel mechanisms of action, new antimetabolites (edatrexate and gemcitabine), and a new vinca alkaloid (vinorelbine). Furthermore, in the near future, the better understanding of lung cancer biology will help in devising new treatment strategies.

Paclitaxel (Taxol) and docetaxel (Taxotere): active chemotherapeutic agents in lung cancer

Paclitaxel (Taxol), the prototype of a new class of plant-derived antineoplastic compounds, is a natural product isolated from the Pacific yew. Docetaxel (Taxotere) is a hemisynthetic product derived from the European yew. These agents share a unique mechanism of cytotoxic action by promoting assembly of microtubules and rendering the microtubules resistant to depolymerization. In vitro studies suggest a possible role for radiation sensitization. In Phase I trials, the dose-limiting toxicity was neutropenia for both agents. Other toxicities include infusion-related hypersensitivity reactions, alopecia, neurotoxicity, mucositis, diarrhoea and myalgias. To prevent infusion-related reactions, routine premedication is recommended. Noncumulative cardiac toxicity has been observed with paclitaxel. Fluid retention and rash have been reported with docetaxel. In Phase II studies of paclitaxel in advanced non-small cell lung cancer, response rates of 21% and 24% were observed. In Phase II studies of docetaxel in similar patients, response rates ranging from 28-38% were reported, including patients previously treated with cisplatin. The most common toxicity in these studies was neutropenia. Combination studies with cisplatin and other agents are in progress. Paclitaxel and docetaxel are among the most active chemotherapeutic agents for non-small cell lung cancer patients. Their testing will dominate trials of new therapies in this disease for years to come.

Peripheral neurotoxicity of taxol in patients previously treated with cisplatin

BACKGROUND

Taxol is a new anticancer drug that acts as a tubulin polymeration enhancer. Its major toxicities are myelosuppression, hypersensitivity, and mucositis, but it also induces peripheral nerve damage. The use of taxol has recently been proposed for platinum-resistant cancers, but in these cases there is a possibility of cumulative toxicity in the peripheral nervous system.

METHODS

Twenty-two patients affected by a relapse of cisplatin-treated ovarian cancer were examined clinically and neurophysiologically to determine the evolution of taxol-induced peripheral somatic and autonomic neurotoxicity and the possible cumulative effect of a combination of taxol and cisplatin. Each patient was examined before, during, and after taxol treatment (using a dose of 135 or 175 mg/m2 in 3 hours every 3 weeks).

RESULTS

No patients were excluded from the study because of unacceptable toxicities of any kind. The serial examinations demonstrated that taxol induced onset of (or worsening of preexisting) neuropathic symptoms and signs in almost all the patients. The features were those of a distal, symmetrical, sensory polyneuropathy due to an axonopathy. Motor nerves and the autonomic nervous system were unaffected. Taxol neurotoxicity appeared early in the course of the treatment (i.e., after three courses) and was not severely disabling. In most cases after the early onset of peripheral neuropathy, stabilization of this side effect occurred.

CONCLUSIONS

Considering the low doses of taxol used in this study, the sensory nerve damage was unexpectedly severe. It appears that a cumulative, but not dose-limiting, neurotoxic effect occurs using taxol in patients previously treated with cisplatin.

Squamous cell carcinoma is highly sensitive to taxol, a possible new radiation sensitizer

We studied the sensitivity of seven cell lines established from laryngeal carcinoma to the cytotoxic drug paclitaxel (Taxol) in vitro. In all four cell lines tested for growth inhibition, paclitaxel reduced growth at low concentrations, and in two cell lines growth was completely inhibited at a paclitaxel concentration of only 1 x 10(-8) M. Flow cytometric data showed a G2/M block in all seven cell lines after exposure to paclitaxel for 24 h at a concentration of 1 x 10(-8) M. This concentration is about one-one hundredth fold smaller than those measured in serum after a single intravenous dose of about 200 mg/m2. The high in vitro sensitivity of laryngeal cancer cell lines to paclitaxel,and the G2/M block suggest that the drug may potentially be used in conjunction with radiotherapy.

Schedule-dependent antagonism of paclitaxel and cisplatin in human gastric and ovarian carcinoma cell lines in vitro

Paclitaxel has demonstrated broad clinical activity in a variety of malignancies both alone and in combination with other chemotherapeutic agents. The in vitro cytotoxicity of paclitaxel and cisplatin alone, in combination and in sequence, were evaluated against established human gastric and ovarian carcinoma cell lines using 2-h drug exposure. The combination of cisplatin and paclitaxel was found to be additive or even synergistic when paclitaxel was given 24 h prior to cisplatin as demonstrated by isobologram analysis. However, when both drugs were given simultaneously or when cisplatin was given prior to paclitaxel, a strong antagonistic interaction was observed. This antagonism was evident for up to 72 h after a 2-h exposure to cisplatin. Pretreatment with cisplatin caused no alteration in [3H]paclitaxel uptake in HM2 gastric carcinoma cells, but resulted in decreased intracellular retention of paclitaxel. Since cisplatin treatment led to a reduction in cellular glutathione content in these cells and reduced levels of glutathione have been associated with protection against cytotoxicity of paclitaxel, cells were pretreated with L-buthionine sulfoximine (L-BSO). However, depletion of glutathione had no influence on the activity of paclitaxel. A significant accumulation of cells in S-phase was observed 24 h after cisplatin, which resolved after 48 h and resulted in a pronounced increase of G2M phase. These data demonstrate that the interactions of paclitaxel and cisplatin are highly schedule-dependent and applications of cisplatin simultaneously with or prior to paclitaxel may result in pronounced antagonism. These findings could have implications for the design of further clinical protocols.

Evaluation of merbarone (NSC 336628) in disseminated malignant melanoma. A Southwest Oncology Group study

Merbarone, NSC 336628, is an investigational anticancer drug with activity against experimental animal tumors including melanoma. This paper presents results of a Phase II clinical study of merbarone in patients with biopsy proven stage IV malignant melanoma without prior chemotherapy and with no evidence of CNS involvement. Thirty-five patients with median age 58 (range 27-81), with performance status 0-2 were treated with merbarone 1000 mg/m2/day for five days by intravenous continuous infusion repeated every 3 weeks. All patients (21 males and 14 females) were evaluable for toxicity. Two patients were not evaluable for response having been removed from protocol treatment due to toxicity and received other treatment during the first course of chemotherapy. Among the evaluable patients there was one complete response in a supraclavicular lymph node lasting four months and one partial liver response lasting three months. The remaining thirty-one patients were non-responders. Of these one had a stable disease lasting 21 months. The overall objective response rate was 6% (2/35) with a 95% confidence interval of 1%-19%. Twenty-six of the 35 patients have died. The estimated median survival of the entire group was 9 months with a 95% confidence interval six to eleven months. Renal toxicity was dose-limiting and manifested as increasing serum creatinine (54% of patients), proteinuria (51%) and hematuria (9%). One patient experienced grade 4 creatinine increase, proteinuria and acute renal failure. Other toxicities included nausea (71%), vomiting (51%0, malaise (23%), weakness (20%), alopecia (17%), diarrhea (17), anorexia (14%) transaminase (SGOT, SGPT) increase (14%), constipation (14%), alkaline phosphatase or 5'nucleotidase increase (9%), and fever (9%). Hematologic toxicity (granulocytopenia, leukopenia, and anemia) was generally mild and infrequent (29%, only one patient had grade 4 granulocytopenia). Overall 9 patients (26%) had at least one grade 3 toxicity. We conclude that merbarone at this dose and schedule has detectable but minimal activity in the treatment of metastatic malignant melanoma and given the significant renal toxicity this schedule does not merit further evaluation in this disease.

Single agent Taxol, 3-hour infusion, in untreated advanced non-small-cell lung cancer

Currently, only a few chemotherapeutic agents have consistently produced single agent response rates greater than 15% in patients with non-small-cell lung cancer (NSCLC). Taxol has been reported in two phase II studies to have significant activity in NSCLC with response rates of 21% and 24%. Schedule infusion of 24 hours has been used to reduce allergic reactions. The study reported here was a phase II trial of Taxol given by 3-hour intravenous infusions at a 210 mg/m2 dose every three weeks in outpatients setting. It was conducted simultaneously at three centers on chemotherapy-naïve patients medicated with unresectable stage III or metastatic NSCLC. Sixty-two patients were initially enrolled; all were premedicated with dexametasone (20 mg), cimetidine (330 mg) and diphenilhydramine (50 mg), given prior to initiation of paclitaxel infusion. Fifty patients were evaluated for toxic effects and 47 for response. Sixteen partial responses (34) and one complete response (2%) were observed, for an overall response rate of 36% (95% confidence internal, 22% to 50%). Taxol was well-tolerated and none of the patients experienced allergic reaction. Granulocytopenia was generally mild. Therapy was interrupted in only two patients because of the development of grade 3 neuropathy. In our experience Taxol is one of the most active cytotoxic drugs targeting non-small-cell lung cancer.

New drugs in the treatment of non-small cell lung cancer

Non-small cell lung cancer accounts for 75% of all lung tumours, and only about 10% of patients will remain alive 5 years after diagnosis. Few cytotoxic drugs currently registered produce more than a 15% response rate as a single agent or 30%-35% in combination, with only modest survival benefits. New cytotoxic drugs entering phase II and III studies, however, appear to have more than 20% activity against this disease. They include the taxanes (taxol and taxotere), camptothecin analogues (CPT-11 and topotecan), antimetabolites (edatrexate and gemcitabine) and the vinca alkaloid, navelbine. Taxol produces response rates of about 25% in previously untreated patients and is currently undergoing trials at higher doses in combination with cisplatin and granulocyte colony-stimulating factor. Taxotere produces response rates of 33% in previously untreated patients and 21% in patients previously refractory to platinum-containing regimens. The camptothecin analogues, which are inhibitors of topoisomerase I, may produce response rates of up to 41% in previously untreated patients, but these results have varied considerably between different trials (response rates as low as 13.5% have been reported for topotecan). A phase II study with edatrexate produced a response rate of 32% but subsequent trials using combination chemotherapy including this agent have been disappointing. The activity of gemcitabine as a single agent is 20%-25%. Three ongoing phase II studies combining cisplatin and gemcitabine have shown response rates of up to 50%. Gemcitabine has minimal subjective toxicity. Navelbine produces response rates of 22%-33% as a single agent and up to 65% in combination. These new cytotoxic agents with significant activity in non-small cell lung cancer provide exciting potential for developing novel combination regimens in the advanced setting and as neoadjuvant and adjuvant therapy.

Chemotherapy of stage IIIB and IV non-small-cell lung cancer

Currently, lung cancer is a leading cause of death in men with more than half million new cases diagnosed every year. Eighty percent of these tumors are non-small-cell carcinoma and 70% of these are unresectable or metastatic at the time of presentation, resulting in dramatically poor survival rates. The increasing number of drugs showing a significant activity against non-small-cell lung cancer and the widespread use of modern cisplatin based regimens offer some hope of progress and suggest that chemotherapy may have a role in treating this disease. A recent meta-analysis has confirmed the modest but significant survival benefit for patients treated with combined chemotherapy both in case of metastatic disease and in addition to radiotherapy, in locally advanced disease.

Taxanes: a new class of antitumor agents

Taxanes belong to a new group of antineoplastic agents with a novel mechanism of action for a cytotoxic drug. They promote microtubule assembly and stabilize the microtubules. Paclitaxel, the first agent in this group to become available, was isolated from the Pacific yew, Taxus brevifolia, in 1971. In preclinical and clinical studies, paclitaxel and its semisynthetic analog docetaxel exhibit significant antitumor activity. This review deals with the physicochemical properties, pharmacology, and results of preclinical and clinical trials of the taxanes.

The distribution of systemically administered [3H]-paclitaxel in rats: a quantitative autoradiographic study

Paclitaxel is an important agent in the treatment of many common malignancies. Although the symptomatic peripheral neuropathy caused by this drug is its principal nonhematologic toxicity, little is known about the distribution of paclitaxel within the peripheral or central nervous system following systemic administration. In order to study paclitaxel's distribution in neural and extraneural tissues, adult Sprague-Dawley rats were sacrificed 2 h after a tail vein injection of [3H]-paclitaxel (0.03 mg/kg, 250 microC/rat). Samples of lung, heart, liver, spleen, kidney, skeletal muscle, brain, spinal cord, dorsal root ganglion, and peripheral nerve were then removed and snap-frozen. These tissues were sectioned at 10 microns in a cryostat and exposed to autoradiography film for 2 weeks. The distribution and concentrations of [3H]-paclitaxel in plasma, urine and cerebrospinal fluid were also determined using liquid scintillation spectrometry. [3H]-paclitaxel concentrations (and organ/plasma concentration ratios) in plasma, urine and cerebrospinal fluid were 2.6 nM (1), 38 nM (15) and 0.7 nM (0.3), respectively. A relatively homogeneous distribution of [3H]-paclitaxel was observed in liver [412 nM (151)], spleen [351 nM (133)], heart [319 nM (117)], lung [268 nM (93)] and muscle [69 nM (26)]. Higher concentrations of [3H]-paclitaxel were noted in the portal triads [869 nM (361)], glomeruli [797 nM (304)], and renal medulla [961 nM (363)], which may reflect biliary excretion and glomerular filtration. A high concentration of [3H]-paclitaxel was also noted in the choroid plexus [432 nM (167)], but [3H]-paclitaxel was not detected in the brain parenchyma, spinal cord, dorsal root ganglion, peripheral nerve, or the testicles. The pathogenesis of paclitaxel-induced neurotoxicity remains obscure given its limited distribution in the nervous system. In addition, these results suggest that systemically administered paclitaxel is not likely to be effective for the treatment of malignancies in the testes or the nervous system.

Future directions in clinical research for lung cancer

Even since the Surgeon General's 1964 report, the mortality rate from lung cancer has continued to rise. Although there is evidence that this continued increase in mortality will slow or level in the next decade, lung cancer mortality is a major health problem destined to remain with us for at least the next generation. There have been no established advances in the early detection or prevention of lung cancer in the last 30 years and our therapies have increased the cure rate only from 5 to 13% in this 30-year interval. Biologic advances have outpaced clinical advances in recent times and many of the advances are now ripe for clinical exploitation. There are currently more exciting clinical trials for all phases of lung cancer than at any time and it will be stimulating to witness the results of the clinical trials discussed herein. Hopefully, the results of these studies will lead to a decrease in lung cancer mortality in the next century, much as it increased in the past century.

Paclitaxel. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic potential in the treatment of cancer

Paclitaxel is a new anticancer agent with a novel mechanism of action. It promotes polymerisation of tubulin dimers to form microtubules and stabilises microtubules by preventing depolymerisation. In noncomparative trials, continuous infusion of paclitaxel 110 to 300 mg/m2 over 3 to 96 hours every 3 to 4 weeks produced a complete or partial response in 16 to 48% of patients with ovarian cancer and 25 to 61.5% of patients with metastatic breast cancer, many of whom were refractory to treatment with cisplatin or doxorubicin, respectively. 23 to 100% of patients with ovarian cancer achieved complete or partial responses with paclitaxel in combination with cisplatin, carboplatin, cyclophosphamide, altretamine and/or doxorubicin. Similarly, response rates of 30 to 100% were observed with paclitaxel plus doxorubicin, cisplatin, mitoxantrone and/or cyclophosphamide in patients with metastatic breast cancer. Comparative trials in patients with advanced ovarian cancer showed paclitaxel therapy to produce greater response rates than treatment with parenteral hydroxyurea (71 vs 0%) or cyclophosphamide (when both agents were combined with cisplatin) [79 vs 63%]. Paclitaxel was also more effective than mitomycin in 50 patients with previously untreated breast cancer (partial response in 20 vs 4% of patients). Paclitaxel therapy also produced promising results in patients with advanced squamous cell carcinoma of the head and neck, malignant melanoma, advanced non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), germ cell cancer, urothelial cancer, oesophageal cancer, non-Hodgkin's lymphoma or multiple myeloma, and was successfully combined with cisplatin, carboplatin and/or etoposide in patients with NSCLC, SCLC or advanced squamous cell carcinoma of the head and neck. Hypersensitivity reactions were initially a concern with administration of paclitaxel, although current dosage regimens have reduced the incidence of these events to less than 5%. The major dose-limiting adverse effects of paclitaxel are leucopenia (neutropenia) and peripheral neuropathy. Other haematological toxicity was generally mild. Cardiac toxicity was reported in small numbers of patients and most patients developed total alopecia. Several aspects of paclitaxel use remain to be clarified, including the optimal treatment schedule and infusion time, confirmation of the tolerability profile and efficacy of combination regimens in an expanded range of malignancies. Long term follow-up of paclitaxel recipients will also allow the effects of the drug on patient survival to be determined. Nevertheless, paclitaxel is a promising addition to the current therapies available, with significant activity reported in patients with advanced ovarian or breast cancer or other types of tumors.(ABSTRACT TRUNCATED AT 400 WORDS)

Phase I and pharmacokinetic study of paclitaxel by 24-hour intravenous infusion

Paclitaxel, a new antitubular agent, appears to be one of the most promising single agents for the chemotherapy of various solid tumors. The primary objectives of this phase I study of paclitaxel using 24-h continuous intravenous infusions were to determine the maximum tolerated dose of paclitaxel administered by this schedule to Japanese patients with solid tumors and to evaluate the pharmacokinetics of paclitaxel. Eighteen patients received one of five doses of paclitaxel, 49.5, 75, 105, 135 or 180 mg/m2. Premedication with diphenhydramine, dexamethasone, and ranitidine was used to prevent acute hypersensitivity reactions. Pharmacokinetic data were obtained from all 18 patients. Dose-limiting toxicities observed at 180 mg/m2 consisted of grade 4 granulocytopenia associated with grade 3 infection. No severe HSRs or cardiac toxicity were detected. Reversible toxicities observed included liver dysfunction, alopecia, peripheral neuropathy and myalgias. Pharmacokinetic studies performed using high-performance liquid chromatography demonstrated that plasma concentrations of paclitaxel increased during the 24-h infusion and declined immediately upon cessation of the infusion with a half life of 13.1-24.6 h (75-180 mg/m2). Less than 10% of paclitaxel was excreted in the urine within 72 h. The peak plasma concentrations and the areas under the concentration-versus-time curves increased linearly with the dose administered. Antitumor activity was observed in one patient with pulmonary metastasis from pharyngeal cancer. Based on these studies a phase II trial dose of 135 mg/m2 administered over 24 h was chosen.

Paclitaxel administered by 1-hour infusion. Preliminary results of a phase I/II trial comparing two schedules

BACKGROUND

Paclitaxel currently is administered by prolonged intravenous infusion because of the occurrence of severe hypersensitivity reactions in patients in early clinical trials. However, intensive premedication probably is more important in eliminating allergic reactions than is the length of infusion. The authors evaluated the feasibility of two paclitaxel schedules using a 1-hour, outpatient infusion.

METHODS

Fifty-six patients with advanced, refractory malignancies were randomized to receive one of two paclitaxel schedules: 135 mg/m2 administered as a single dose over 1 hour, or 135 mg/m2 administered in divided daily doses for 3 days, each over 1 hour. All patients were premedicated with dexamethasone, diphenhydramine, and cimetidine.

RESULTS

No serious hypersensitivity reactions occurred with either schedule of paclitaxel. In addition, other adverse effects were usually mild and easily tolerated. Other than alopecia, which occurred in all patients, myelosuppression was the most common severe toxicity. However, grade 3 leukopenia occurred in only 19% of treatment courses, and grade 4 leukopenia (nadir < 1000/microL) occurred in only 2%. Nine patients required hospitalization for treatment of infection associated with neutropenia. No significant differences in toxicity were observed when the two paclitaxel regimens were compared. Although it is too early to assess the results adequately, preliminary findings showed that thus far 11 of 56 patients (20%) had a partial or complete response to therapy. Responses were observed in patients with breast, ovarian, and lung cancer.

CONCLUSIONS

Paclitaxel can be safely administered in a 1-hour infusion in an outpatient setting, either as a single dose or in divided doses for three days. Severe hypersensitivity reactions did not occur in 162 treatment courses, and neutropenia was mild in most patients. Incorporation of this dose and these schedules of paclitaxel into combination chemotherapy regimens should be feasible. An investigation of higher paclitaxel doses given in a 1-hour infusion is currently in progress.

Quality of life during clinical trials: conceptual model for the Lung Cancer Symptom Scale (LCSS)

To appreciate the full benefits of treatment for lung cancer, especially in trials that fail to show improvements in survival, data recording the quality of life must be captured and refined to produce meaningful information. A conceptual model for quality of life for lung cancer patients was tested to obtain information about the dimensions of the quality-of-life construct for ongoing development and testing of a subjective measure for clinical trials. Using a longitudinal study design, the stability of predictive factors of the physical and functional dimensions of quality of life were examined using regression analysis. A patient-rated quality-of-life measure, the Lung Cancer Symptom Scale (LCSS), was administered to 144 non-small-cell lung cancer patients at baseline, day 29, and day 71 of a chemotherapy trial. The range of explained variance for all three components of the lung cancer model over three assessment points was as follows: symptomatic distress 41%-53%, activity status 48%-52%, and overall quality of life 35%-53%. The three dimensions fluctuated slightly during intervention, but were relatively stable factors across all three times of evaluation. The LCSS model explained nearly half of the variance for quality of life experienced by lung cancer patients during therapy with a new chemotherapeutic agent. These findings provide support that the physical and functional dimensions are important predictors of quality of life for individuals with lung cancer. Meaningful subjective quality-of-life data can be obtained to evaluate an intervention by using a disease- and site-specific quality-of-life measure for individuals with lung cancer, based on a reproducible conceptual model such as the LCSS, which is suitable for serial measurement for the progressive disease of lung cancer.

Paclitaxel (Taxol) and docetaxel (Taxotere): not simply two of a kind

Paclitaxel and docetaxel are the two presently clinically available representatives of the new class of taxane drugs. They share major parts of their structures and mechanisms of action, but differ in several other aspects. For instance, there is a difference in their tubulin polymer generation, and docetaxel appears twice as active in depolymerization inhibition. In vitro docetaxel also tends to be more potent in different cell lines and investigational models. While in vitro and in vivo studies suggest that prolonged exposure to paclitaxel is better than a brief exposure, no such tendency is seen for docetaxel, indicating it to be a schedule-independent drug. Clinical studies have not confirmed an advantage for prolonged exposure to paclitaxel; but do show differences in the toxicity profiles of the two drugs. These topics will be addressed in detail.

Paclitaxel (Taxol): a novel anticancer chemotherapeutic drug

OBJECTIVE

To review the literature on the clinical activity and toxic effects of paclitaxel (Taxol).

DESIGN

Results of phase I and II trials of Taxol in patients with various types of tumors are provided.

MATERIAL AND METHODS

Taxol is the first drug in a new class of antineoplastic agents known as the taxanes. These drugs demonstrate a novel mechanism of action characterized by promotion of the assembly of microtubules and stabilization of the tubules against depolymerization, resulting in mitotic arrest.

RESULTS

Numerous phase I and phase II trials have demonstrated the efficacy of Taxol in refractory ovarian carcinoma, breast carcinoma, lung cancer, head and neck cancer, and lymphoma. Various durations of infusions of Taxol have been used in several studies. In the treatment of most patients with ovarian cancer, Taxol can probably be administered by either short infusion or 24-hour infusion with no compromise in antitumor effect. Neutropenia seems to be less common when 3-hour infusions are used. Additional phase II trials are currently in progress, as are combination chemotherapy trials.

CONCLUSION

Taxol has definite antitumor activity in advanced ovarian and breast cancers and seems to have activity in lung cancer. Further clinical trials will determine the spectrum of activity of Taxol in other malignant tumors and define its role in combination chemotherapy for sensitive tumor types.

Clinical, toxicological and pharmaceutical aspects of the antineoplastic drug taxol: a review

Taxol, a diterpene alkaloid isolated from the bark of Taxus brevifolia, has a unique mechanism of action. The drug promotes the formation of microtubule polymers in a cell, by reversibly and specifically binding the beta-subunit of tubulin. Taxol is administered intravenously by a 3-24-hour infusion at 3-week intervals. Myelosuppression, especially neutropenia, appears to be the dose limiting toxicity in solid tumours at 200-250 mg/m2. Furthermore, side effects such as sensory neurotoxicity (with typical numbness, tingling and painful paraesthesiae in the extremities), diarrhoea and alopecia appear frequently. Mucositis appears to be the non-haematological dose limiting side effect at 390 mg/m2 that has been determined in patients with leukaemia. Hypersensitivity reactions, which have been fatal in individual cases, might be schedule dependent. Furthermore, antiallergic prophylaxis must be given, although this precaution might not be considered to be fully protective. Phase I studies performed with combinations of taxol and cisplatin, doxorubicin or cyclophosphamide have indicated the feasibility of these regimens and show promise for future investigations. Addition of granulocyte-colony stimulating factor (G-CSF), aimed at modulating myelosuppressive toxicity, showed in Phase I studies that the taxol dose could be increased to 250 mg/m2, with peripheral neuropathy as the dose limiting toxicity. In Phase II studies, taxol has been shown to be effective, including producing complete tumour remission, in advanced drug refractory ovarian carcinoma (19%-36% response rate), previously treated patients with metastatic breast carcinoma (27%-62% response rate), advanced non-small lung cancer (21%-24% response rate), advanced small cell lung cancer (37% response rate) and advanced head and neck cancer (34% response rate).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma pharmacokinetics and tissue distribution of paclitaxel in CD2F1 mice

We defined the pharmacokinetics of paclitaxel after i.v., i.p., p.o., and s.c. administration of 22.5 mg/kg to CD2F1 mice. Additional mice were studied after i.v. bolus dosing at 11.25 mg/kg or 3-h continuous i.v. infusions delivered at 43.24 micrograms kg-1 min-1. Plasma was sampled between 5 min and 40 h after dosing. Brains, hearts, lungs, livers, kidneys, skeletal muscles, and, where applicable, testicles were sampled after i.v. dosing at 22.5 mg/kg. Liquid-liquid extraction followed by isocratic high-performance liquid chromatography (HPLC) with UV detection was used to determine paclitaxel concentrations in plasma and tissues. After i.v. administration to male mice, paclitaxel clearance (CLtb) was 3.25 ml min-1 kg-1 and the terminal half-life (t1/2) was 69 min. After i.v. administration to female mice, paclitaxel CLtb was 4.54 ml min-1 kg-1 and the terminal t1/2 was 43 min. The bioavailability of paclitaxel was approximately 10%, 0, and 0 after i.p., p.o., and s.c. administration, respectively. Paclitaxel bioavailability after i.p. administration was the same when the drug was delivered in a small volume to mimic the delivery method used to evaluate in vivo antitumor efficacy or when it was delivered in a large volume to simulate clinical protocols using i.p. regional therapy. Paclitaxel was not detected in the plasma of mice after i.p. delivery of the drug as a suspension in Klucel: Tween 80. Pharmacokinetic parameters were similar after i.v. delivery of paclitaxel at 22.5 and 11.25 mg/kg; however, the CLtb calculated in these studies was much lower than that associated with 3-h continuous i.v. infusions. After i.v. administration, paclitaxel was distributed extensively to all tissues but the brain and testicle. These data are useful in interpreting preclinical efficacy studies of paclitaxel and predicting human pharmacokinetics through scaling techniques.

Phase II trial of piroxantrone in metastatic breast cancer. A Southwest Oncology Group study

Thirty-two eligible patients with advanced metastatic breast cancer who had received no more than 1 prior chemotherapy regimen for metastatic disease (16 had received prior doxorubicin) were treated with piroxantrone at a dose of 120 mg/m2 intravenously every 21 days. In the twenty-seven patients evaluable for response, two partial responses were seen. Toxicities observed were primarily hematologic with grade 3 or greater granulocytopenia occurring in 34% of the patients. One patient developed symptomatic congestive heart failure at a total cumulative dose of 960 mg/m2. We conclude that piroxantrone given at this dose and schedule has minimal activity in patients with metastatic breast cancer.

Hepatoma/merbarone. A Southwest Oncology Group study

Sixteen eligible patients with hepatocellular carcinoma, previously untreated, received merbarone 1000 mg/m2/d for five consecutive days every 21 days. No complete or partial response to treatment was obtained. Seven patients had grade 4 granulocytopenia. One patient died with renal failure. Merbarone in this dose and schedule was ineffective in the treatment of hepatocellular carcinoma.

Taxol (paclitaxel): a novel anti-microtubule agent with remarkable anti-neoplastic activity

Taxol (paclitaxel), an anti-microtubule agent extracted from the needles and bark of the Pacific yew tree Taxus brevifolia, has shown a remarkable anti-neoplastic effect in human cancer in phase I studies and early phase II and III trials thus far conducted. This has been reported primarily in advanced ovarian and breast cancer, although significant activity has also been documented in small-cell and non-small-cell lung cancer, head and neck cancers, and with lower activity in metastatic melanoma. The clinical utilization of Taxol had been previously somewhat restricted by its limited availability, a limitation that has recently been overcome by combined efforts of pharmaceutical, agricultural, and governmental agencies. In this review we shall address the pre-clinical data which have led to the use of Taxol in man, the main clinical results thus far obtained, the toxicities associated with its use, current ongoing trials and future clinical directions of this promising agent.

Paclitaxel (taxol)

Paclitaxel is a novel antineoplastic that effects cytotoxicity by promoting intracellular tubulin polymerization and stabilizes abnormal microtubule structures against depolymerization. Although its clinical development had been hampered by misconceptions about its pharmacology, its scarcity, difficulties extracting it from its natural source, formulation problems, and frequent severe hypersensitivity reactions, paclitaxel recently was approved for treatment-refractory ovarian cancer. Two major adverse effects are dosage- and schedule-related myelosuppression and mucositis. Neurotoxicity is directly related to both the individual and cumulative doses. Other relevant toxicities are hypersensitivity reactions, effects on cardiac rate and rhythm, arthralgias and myalgias, generalized hair loss, and mild nausea and emesis. Continuing clinical studies will evaluate paclitaxel as initial therapy for ovarian cancer and its utility in other malignancies. In addition, major efforts are under way to develop alternative sources to increase the availability of taxene analogs and reduce our dependence on yew species.

Postoperative chemotherapy for resected non-small-cell lung cancer

Surgical resection is the treatment of choice for patients with stage I and stage II non-small-cell lung cancer (NSCLC--squamous cell, adenocarcinoma, and large-cell carcinoma). Distant recurrence is an important cause of death after complete surgical resection, occurring in 30-60% of patients. Postoperative adjuvant chemotherapy has been studied for over three decades in randomized controlled trials but is not considered standard therapy for this group of patients. The use of multidrug regimens including cisplatin has produced a prolongation of disease-free survival, but until recently no overall survival benefit has been shown. A new generation of studies is now warranted, employing the more active combinations identified in the 1980s or incorporating one of the many promising new agents being tested in NSCLC. The use of improved supportive care measures, such as the new serotonin receptor antagonist antiemetics, is required to increase compliance with chemotherapy in this group of patients. With this approach, the real goal of adjuvant system chemotherapy--to increase the number of patients actually cured of their cancer--may be attained in early stage NSCLC.

Ethical issues and paclitaxel (TAXOL) administration

Although less concrete than the practical issues involved in the administration of paclitaxel, the ethical concerns are nonetheless important. Anything that elicits the broad range of emotions shown by individuals seeking, receiving, or administering paclitaxel is bound to raise ethical concerns. General ethical principles can be applied to the "paclitaxel experience." It is helpful to look at ethical principles within the context of pressure exerted on caregivers to provide paclitaxel. These pressures include high media profile of the drug, reported drug activity, and environmental issues. The high media profile has led to tremendous public demand, which has in turn influenced access and referral issues. When a new, promising drug is released, it is important for those nurses who have worked with the drug in clinical trials to participate in the transfer of technical information to the community. This must include information designed to sensitize caregivers to the variety of issues and concerns raised in relation to the drug that they provide.

The taxoids: paclitaxel (Taxol) and docetaxel (Taxotere)

The taxoids, paclitaxel (Taxol) and docetaxel (Taxotere), represent a novel class of antineoplastic drugs. Paclitaxel and docetaxel share a similar mechanism of action: the promotion of microtubule assembly and inhibition of microtubule disassembly. The clinical development of paclitaxel was initially hampered by hypersensitivity reactions (HSRs). The use of premedications and prolongation of the infusion time to 24h has reduced these reactions and allowed this drug's clinical development. Although paclitaxel's clinical activity has not been fully investigated, clinical trials have demonstrated its activity against ovarian, breast, and bronchial carcinomas. Because phase I studies of docetaxel noted occasional HSRs and these observations increased with further clinical experiences, those premedications employed with paclitaxel have now been instituted in many phase II studies of docetaxel. Docetaxel is currently being investigated in ovarian, breast, and bronchial carcinomas and has shown impressive clinical activity. The dose-limiting toxicity of both these agents is neutropenia; myalgias, mucositis, neuropathies, and alopecia have also been observed with both drugs. Additionally, a fluid retention syndrome and cutaneous toxicities have been noted in patients treated with docetaxel. Future studies of the taxoids will allow further comparisons of the toxicity and efficacy of these agents.

An overview of experience with TAXOL (paclitaxel) in the U.S.A

TAXOL (paclitaxel) is a unique new antineoplastic agent that has generated a considerable amount of scientific interest from many disciplines since it entered clinical trials in the early 1980s. There are a number of reasons for this interest. The natural biological source for this agent is the bark of the Pacific yew in the ancient forests of the northwestern U.S.A. The initial problems with supply of the agent and the desirability of a renewable source has stimulated the creativity of medicinal chemists and others interested in alternate sources of supply. The unique mechanism of action and the effect of TAXOL on microtubule structure and function continues to be the subject of intense investigative interest. Clinical investigators have had to contend with troublesome and potentially serious toxicities, which have threatened the development of TAXOL, but have been rewarded with a drug that appears to have broad antitumor activity against a number of advanced solid tumors in man. The purpose of this review is to provide an overview of the clinical experience with TAXOL, which has been developed in the U.S.A. over the last 10 years with more than 4,000 patients, and to outline what issues remain in the optimization of its use.

Small cell lung cancer: etiology, biology, clinical features, staging, and treatment

Lung cancer is the leading cause of cancer death in the United States. Small cell lung cancer (SCLC) accounts for 20% to 25% of all bronchogenic carcinoma and is associated with the poorest 5-year survival of all histologic types. SCLC differs in its etiologic, pathologic, biologic, and clinical features from non-SCLC, and these differences have translated to distinct approaches to its prevention and treatment. Compared with other histologic types of lung cancer, exposures to tobacco smoke, ionizing radiation, and chloromethyl ethers pose a substantially greater risk for development of SCLC. The histologic classification of SCLC has been revised to include three categories: (1) small cell carcinoma, (2) mixed small cell/large cell, and (3) combined small cell carcinoma. Ultrastructurally, SCLC displays a number of neuroendocrine features in common with pulmonary neuroendocrine cells, including dense core vesicles or neurosecretory granules. These dense core vesicles are associated with a variety of secretory products, cell surface antigens, and enzymes. The biology of SCLC is complex. The activation of a number of dominant proto-oncogenes and the inactivation of tumor suppressor genes in SCLC have been described. Dominant proto-oncogenes that have been found to be amplified or overexpressed in SCLC include the myc family, c-myb, c-kit, c-jun, and c-src. Altered expression of two tumor suppressor genes in SCLC, p53 and the retinoblastoma gene product, has been demonstrated. Cytogenetic and molecular evidence for chromosomal loss of 3p, 5q, 9p, 11p, 13q, and 17p in SCLC has intensified the search for other tumor suppressor genes with potential import in this malignancy. Bombesin/gastrin-releasing peptide, insulin-like growth factor I, and transferrin have been identified as autocrine growth factors in SCLC, with a number of other peptides under active investigation. Several mechanisms of drug resistance in SCLC have been described, including gene amplification, the recently described overexpression of multi-drug resistance-related protein (MRP), and the expression of P-glycoprotein. The classic SCLC staging system has been supplanted by a revised TNM staging system where limited disease and extensive disease are equivalent to the TNM stages I through III and stage IV, respectively. Therapeutically, recent strategies have attained small improvements in survival but significant reductions in the toxicities of chemotherapeutic regimens. Presently, the overall 5-year survival for SCLC is 5% to 10%, with limited disease associated with a significantly higher survival rate.(ABSTRACT TRUNCATED AT 400 WORDS)