A review of the pharmacology and clinical activity of new chemotherapeutic agents in lung cancer

99m Tc-tricarbonyl labeling of paclitaxel as an antimicrotubule agent and its evaluation in B16-F10 melanoma tumor-bearing mice

In the present study paclitaxel (taxol) was labeled with [^99m Tc(CO)₃ (H₂ O)₃ ]⁺ core. Labeling was optimized, and radiochemical analysis was determined by thin layer chromatography and high performance liquid chromatography. Radiocomplex was evaluated and verified further as a tumor characterization agent in B16-F10 melanoma tumor-bearing mice. The [^99m Tc(CO)₃ (H₂ O)₃ ]⁺ -paclitaxel complex with high specific activity (0.77 GBq/μmol) and labeling yield (96.8 ± 1.3) was obtained. No decrease in labeling was observed up to 6 hours, and the stability of the radiocomplex was found adequate. Our main achievement was high accumulation of radiolabeled paclitaxel in tumor (4.51 ± 0.65 percentage injected dose per gram [%ID/g] at 2-h postinjection) followed by significant reduction (1.86 ± 0.27%ID/g) at 4-hour postinjection. Because paclitaxel is a substrate for multidrug resistance, ^99m Tc-tricarbonyl-paclitaxel imaging would be useful for tumor characterization rather than tumor detection.

Differential rates of glucuronidation for 7-ethyl-10-hydroxy-camptothecin (SN-38) lactone and carboxylate in human and rat microsomes and recombinant UDP-glucuronosyltransferase isoforms

7-ethyl-10-hydroxy-camptothecin (SN-38), the active metabolite of the anti-cancer agent irinotecan, contains a lactone ring that equilibrates with a carboxylate form. Since SN-38 lactone is the active and toxic form, it is prudent to examine whether the more soluble carboxylate is a surrogate for SN-38 lactone conjugation. Therefore, relative rates of glucuronidation and isoform specificity of SN-38 lactone and carboxylate were characterized. The stability of SN-38 lactone and carboxylate in incubation mixtures of microsomes and UDP-glucuronosyltransferase (UGT) isoforms was used to determine optimal incubation times. Microsomal incubations were conducted using rat and human intestinal and hepatic microsomes and human and rat recombinant UGT1A isoforms. Where estimates of lactone and carboxylate glucuronidation rates could not be established due to short incubation times and detection limits, kinetic modeling was used to recover these rate constants. The stability experiments revealed that the lactone was stabilized by rat microsomes, however, the opposite was observed in human microsomes and recombinant isoforms. For all tissues and most UGT isoforms examined, the lactone consistently had catalytic rates up to 6-fold greater than the carboxylate. The rank order of glucuronidation for both SN-38 lactone and carboxylate was 1A7 > 1A1 > 1A9 > 1A8 and 1A7 > 1A8 > 1A1 for human and rat isoforms, respectively. This study provides further support that SN-38 lactone and carboxylate may be considered pharmacokinetically distinct agents. The in vivo impact of this conjugation difference is unknown, since variations in protein binding and transport proteins may affect intracellular concentrations of the lactone or carboxylate.

Antitumor activity of erlotinib (OSI-774, Tarceva) alone or in combination in human non-small cell lung cancer tumor xenograft models

Our objective was the preclinical assessment of the pharmacokinetics, monotherapy and combined antitumor activity of the epidermal growth factor receptor (HER1/EGFR) tyrosine kinase inhibitor erlotinib in athymic nude mice bearing non-small cell lung cancer (NSCLC) xenograft models. Immunohistochemistry determined the HER1/EGFR status of the NSCLC tumor models. Pharmacokinetic studies assessed plasma drug concentrations of erlotinib in tumor- and non-tumor-bearing athymic nude mice. These were followed by maximum tolerated dose (MTD) studies for erlotinib and each chemotherapy. Erlotinib was then assessed alone and in combination with these chemotherapies in the NSCLC xenograft models. Complete necropsies were performed on most of the animals in each study to further assess antitumor or toxic effects. Erlotinib monotherapy dose-dependently inhibited tumor growth in the H460a tumor model, correlating with circulating levels of drug. There was antitumor activity at the MTD with each agent tested in both the H460a and A549 tumor models (erlotinib 100 mg/kg: 71 and 93% tumor growth inhibition; gemcitabine 120 mg/kg: 93 and 75% tumor growth inhibition; cisplatin 6 mg/kg: 81 and 88% tumor growth inhibition). When each compound was given at a fraction of the MTD, tumor growth inhibition was suboptimal. Combinations of gemcitabine or cisplatin with erlotinib were assessed at 25% of the MTD to determine efficacy. In both NSCLC models, doses of gemcitabine (30 mg/kg) or cisplatin (1.5 mg/kg) with erlotinib (25 mg/kg) at 25% of the MTD were well tolerated. For the slow growing A549 tumor, there was significant tumor growth inhibition in the gemcitabine/erlotinib and cisplatin/erlotinib combinations (above 100 and 98%, respectively), with partial regressions. For the faster growing H460a tumor, there was significant but less remarkable tumor growth inhibition in these same combinations (86 and 53% respectively). These results show that in NSCLC xenograft tumors with similar levels of EGFR expression, the antitumor activity of erlotinib is robust both as monotherapy and in combination with chemotherapies.

A phase II trial of vinorelbine plus gemcitabine in previously untreated inoperable (stage IIIb/IV) non-small-cell lung cancer patients aged 80 or older

Vinorelbine and gemcitabine are two active single agents with mild toxicity profiles that are used in the treatment of non-small-cell lung cancer (NSCLC). Whether or not very old NSCLC patients, such as those aged 80 years or older, should still be considered for chemotherapy is unknown, since their response to the treatment is also unknown. A phase II clinical trial was conducted to evaluate the efficacy and toxicity of vinorelbine plus gemcitabine in very old patients with inoperable (stage IIIb or IV) NSCLC. Vinorelbine 20 mg/m(2) was given as a 10-min intravenous infusion, followed by a 30-min intravenous infusion of gemcitabine 800 mg/m(2) on days 1, 8, and 15 of each 28-day cycle. From March 1998 to December 2001, 20 patients (16 males, four females) were enrolled in the study. The median age was 83 years, within the range 80-88 years. The median number of treatment cycles per patient was four. With the exception of one, all patients received at least two cycles of treatment. Thirteen patients achieved a partial response, with an overall response rate of 65% (95% confidence interval, 44.1-85.9%). Median survival was 10 months. The significant (WHO grade 3/4) toxicities were myelosuppression, including leukopenia in five (25%) patients, neutropenia in eight (40%), anaemia in six (30%), and thrombocytopenia in three (15%) patients. Febrile neutropenia occurred in two patients and accounted for one treatment-related death. Non-haematological toxicity was generally mild, except one patient who suffered from grade 3 interstitial pneumonitis. Another patient suffered from a cerebral infarction after three cycles of treatment. In conclusion, the combination of vinorelbine and gemcitabine in very old patients with advanced NSCLC is a highly active regimen with an acceptable toxicity profile.

Pemetrexed (Alimta) and gemcitabine in breast cancer patients previously treated with anthracyclines and taxanes

Gemcitabine (2',2'-difluorodeoxycytidine) is a pyrimidine antimetabolite with broad activity in a variety of solid tumors including breast cancer. Pemetrexed (Alimta) is a novel, multitargeted antifolate that inhibits 3 folate-dependent enzymes, and is also broadly active in a wide variety of solid tumors. In breast cancer, pemetrexed has activity in patients previously treated with anthracyclines and taxanes, and pemetrexed demonstrates preclinical and clinical cytotoxic synergy with gemcitabine. This drug combination is being evaluated in a phase II study for the treatment of metastatic breast cancer patients who have previously received a taxane and an anthracycline.

Gemcitabine and pemetrexed disodium combinations in vitro and in vivo

Pemetrexed disodium (ALIMTA) is a novel antimetabolite that inhibits at least three folate-dependent enzymes, thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase. Pemetrexed disodium is broadly active in a wide variety of solid tumours, including non-small cell lung, breast, bladder, head and neck and ovarian cancers. Gemcitabine is a broadly active pyrimidine nucleoside antimetabolite, which is approved for the treatment of pancreatic and non-small cell lung cancers. Three preclinical studies have been reported that show cytotoxic synergy between gemcitabine and pemetrexed. Clinical activity with this combination has been observed in a phase I study, with partial responses in three of five patients previously treated for non-small cell lung cancer. An international phase II study of this combination in non-small cell lung cancer is ongoing.

Sequence dependent effect of paclitaxel on gemcitabine metabolism in relation to cell cycle and cytotoxicity in non-small-cell lung cancer cell lines

Gemcitabine and paclitaxel are active agents in the treatment of non-small-cell lung cancer (NSCLC). To optimize treatment drug combinations, simultaneously and 4 and 24 h intervals, were studied using DNA flow cytometry and multiple drug effect analysis in the NSCLC cell lines H460, H322 and Lewis Lung. All combinations resulted in comparable cytotoxicity, varying from additivity to antagonism (combination index: 1.0-2.6). Gemcitabine caused a S (48%) and G1 (64%) arrest at IC-50 and 10 x IC-50 concentrations, respectively. Paclitaxel induced G2/M arrest (70%) which was maximal within 24 h at 10 x IC-50. Simultaneous treatment increased S-phase arrest, while at the 24 h interval after 72 h the first drug seemed to dominate the effect. Apoptosis was more pronounced when paclitaxel preceded gemcitabine (20% for both intervals) as compared to the reverse sequence (8%, P = 0.173 for the 4 h and 12%, P = 0.051 for the 24 h time interval). In H460 cells, paclitaxel increased 2-fold the accumulation of dFdCTP, the active metabolite of gemcitabine, in contrast to H322 cells. Paclitaxel did not affect deoxycytidine kinase levels, but ribonucleotide levels increased possibly explaining the increase in dFdCTP. Paclitaxel did not affect gemcitabine incorporation into DNA, but seemed to increase incorporation into RNA. Gemcitabine almost completely inhibited DNA synthesis in both cell lines (70-89%), while paclitaxel had a minor effect and did not increase that of gemcitabine. In conclusion, various gemcitabine-paclitaxel combinations did not show sequence dependent cytotoxic effects; all combinations were not more than additive. However, since paclitaxel increased dFdCTP accumulation, gemcitabine incorporation into RNA and the apoptotic index, the administration of paclitaxel prior to gemcitabine might be favourable as compared to reversed sequences.

Phase II study of tamoxifen, ifosfamide, epirubicin and cisplatin combination chemotherapy in patients with non-small cell lung cancer failing previous chemotherapy

We conducted a phase II study of tamoxifen, ifosfamide, epirubicin, and cisplatin (TIEP) chemotherapy in patients with non-small cell lung cancer (NSCLC) who had failed previous chemotherapy, in order to assess the response and toxicity of TIEP. Between November 1997 and May 1999, 25 patients were treated. Twelve of the 25 patients (48%) had been previously treated with cisplatin-based combination chemotherapy. TIEP doses were tamoxifen 60 mg oral twice daily on days 1-3; ifosfamide 2.4 g/m(2) intravenous infusion (IV) 60 min with mesna on day 2; epirubicin 40 mg/m(2) IV bolus on day 2; and cisplatin 50 mg/m(2) IV 60 min on day 2 every 4 weeks for up to six cycles. Seventy one cycles were given to 25 patients, with a median of three cycles (range one to six cycles). All patients were evaluable for toxicity profile and response rate. As expected, the major toxicity was myelosuppression. Grade 3 or 4 neutropenia occurred in 15 patients (60%) during treatment, as well as in 31% of the total courses. Febrile neutropenia occurred in two patients. No toxic death occurred in this study. Grade 3 thrombocytopenia occurred in five patients with five cycles. Toxicities other than myelosuppression were few and mild in severity. After two cycles of treatment, five of 25 patients (20%) had a partial response (95% confidence interval 4.3-35.7%). Among 12 patients previously treated with cisplatin-based chemotherapy, three patients (25%) achieved a partial response. The median time to disease progression was 4.9 months and median survival was 7.7 months. The response rate and median survival were better than in our previous study of salvage chemotherapy with ifosfamide, 5-FU, and leucovorin; and with ifosfamide, epirubicin, 5-FU, and leucovorin. In conclusion, TIEP appears to be an active combination regimen with an acceptable toxicity profile in Chinese patients with NSCLC who have failed previous chemotherapy.

A multicenter phase II trial of vinorelbine plus gemcitabine in previously untreated inoperable (Stage IIIB/IV) non-small cell lung cancer

STUDY OBJECTIVE

Vinorelbine and gemcitabine are two active single agents used in the treatment of non-small cell lung cancer (NSCLC). A clinical trial was conducted to evaluate the efficacy and toxicity of vinorelbine plus gemcitabine in patients with inoperable (stage IIIB or IV) NSCLC.

DESIGN

A multicenter phase II study. Vinorelbine, 20 mg/m(2), was given as a 10-min IV infusion, followed by a 30-min IV infusion of gemcitabine, 800 mg/m(2), on days 1, 8, and 15 of each 28-day cycle.

PATIENTS AND MEASUREMENTS

From March 1998 to August 1998, 40 patients were enrolled in the study. The efficacy and toxicity of the treatment were recorded.

RESULTS

All patients are evaluable for treatment response and toxicity profile. Two patients achieved a complete response, and 27 patients achieved a partial response, with an overall response rate of 72.5% (95% confidence interval, 58.7 to 86.3%). Median survival time was 11 months. The significant (World Health Organization grade, 3/4) toxicities were myelosuppression, including leukopenia (47.5% of patients), anemia (17.5% of patients), and thrombocytopenia (12.5% of patients). However, febrile neutropenia occurred in three patients and accounted for one treatment-related death. Fatigue, or flu-like syndrome, occurred in 17 patients, and the symptoms were reversed spontaneously 1 to 2 days after injection in 10 patients. Another seven patients needed dose reduction to ameliorate symptoms. Interstitial pneumonitis occurred in six patients who recovered after steroid treatment. No patient suffered from grade 3 or 4 nausea/vomiting.

CONCLUSION

The combination of vinorelbine and gemcitabine in patients with advanced NSCLC is a highly active non-cisplatin-containing regimen with an acceptable toxicity profile.

Phase I and pharmacologic study of sequences of gemcitabine and the multitargeted antifolate agent in patients with advanced solid tumors

PURPOSE

Multitargeted antifolate (MTA) is an investigational agent that, like gemcitabine, exhibits broad activity in solid tumors. A phase I trial of MTA and gemcitabine was undertaken, based on the demonstration of preclinical cytotoxic synergy.

PATIENTS AND METHODS

Thirty-five patients (group I) received 164 courses (median, four; range, one to 14 courses) of treatment of gemcitabine at doses of 1,000 and 1,250 mg/m(2) on days 1 and 8 and MTA at doses of 200, 300, 400, 500, and 600 mg/m(2), given 90 minutes after gemcitabine on day 1. Courses were repeated every 3 weeks. Because the day 8 dose of gemcitabine was reduced or omitted in 57% of courses due to neutropenia, 21 patients (group II) were treated on an alternate schedule, with MTA administered on day 8 rather than day 1. This group received 85 treatment courses (median, four; range, one to 10 courses).

RESULTS

The most common and dose-limiting toxicity was neutropenia. Other toxicities included nausea, fatigue, rash, and elevated hepatic transaminases. The maximum-tolerated dose was gemcitabine/MTA 1,000/500 mg/m(2) for group I and 1,250/500 mg/m(2) for group II. Thirteen objective responses were documented (colorectal cancer, n = 3; non-small-cell lung cancer, n = 3; cholangiocarcinoma, n = 2; ovarian carcinoma, n = 2; mesothelioma, n = 1; breast cancer, n = 1; and adenocarcinoma of unknown primary site, n = 1). Gemcitabine had no effect on the disposition of MTA.

CONCLUSION

The gemcitabine/MTA combination is broadly active and warrants further evaluation. The sequence of gemcitabine administered on days 1 and 8 with MTA administered on day 8 is better tolerated and is recommended for further study at doses of gemcitabine/MTA 1,250/500 mg/m(2).

A phase II trial of tamoxifen, ifosfamide, epirubicin, and cisplatin combination chemotherapy for inoperable non-small-cell lung cancer

A phase II trial of tamoxifen, ifosfamide, epirubicin, and cisplatin (TIEP) chemotherapy was conducted in patients with chemonaive inoperable non-small-cell lung cancer (NSCLC) to assess response and toxicity. From October 1997 to August 1998, 19 patients were treated. The treatment schema included tamoxifen 60 mg twice daily by mouth on days 1 to 3, ifosfamide 3 g/m2 intravenous infusion (IV) 60 minutes with mesna on day 2, epirubicin 50 mg/m2 IV bolus on day 2, and cisplatin 60 mg/m2 IV 60 minutes on day 2 every 4 weeks for up to six cycles. All patients were evaluable for response and toxicity. The major toxicity was myelosuppression; grade 3 or 4 leukopenia or neutropenia occurred in 14 of 19 (73.7%) patients during treatment, and 6 patients (31.6%) experienced fever in association with the neutropenia; no toxic deaths occurred. Grade 3 anemia occurred in six patients (31.6%) during the treatment. Grade 3 or 4 nausea/vomiting occurred in only one patient. Toxicities other than neutropenia and anemia were minimal. After two cycles of treatment, 9 of 19 patients attained a partial response (47.4%, 95% confidence interval 24.9%-69.9%) in this study. The median time to disease progression was 6 months and median survival time was 12 months. We conclude that TIEP is an active combination regimen with an acceptable toxicity profile in Chinese patients with inoperable NSCLC.