Phase II trial of docetaxel-irinotecan combination in advanced esophageal cancer.

BACKGROUND: Preclinical evidence suggests synergy between docetaxel and irinotecan, two drugs active in esophagogastric cancer. We previously demonstrated the safety of docetaxel 35 mg/m2 and irinotecan 50 mg/m2 given on days 1 and 8 of a 21-day schedule. MATERIALS AND METHODS: Patients who had unresectable/metastatic squamous cell carcinoma or adenocarcinoma of the esophagus, measurable disease, Eastern Cooperative Oncology Group performance status of zero to two, and normal bilirubin were eligible. Tumor assessment was carried out every three cycles. RESULTS: We enrolled 29 chemotherapy-naive (CN) and 15 chemotherapy-exposed (CE) eligible patients. Principal toxic effects were diarrhea, neutropenia, and hyperglycemia. There were no toxic deaths. There was one early death, from myocardial infarction. Among 26 CN and assessable patients, there were seven (26.9%) with a partial response (PR) and one (3.8%) with a complete response (CR). There were two PRs and one CR among the patients with CE disease. Median time to progression for CN patients was 4.0 months and for CE patients 3.5 months. Median survival for CN eligible patients was 9.0 months and for CE patients 11.4 months. CONCLUSIONS: Docetaxel-irinotecan combination given on a weekly x 2 of 3 schedule is promising in the treatment of advanced esophageal cancer.

CTGF, intestinal stellate cells and carcinoid fibrogenesis.

AIM: To investigate the role of small intestinal carcinoid tumor-derived fibrotic mediators, TGFbeta1 and CTGF, in the mediation of fibrosis via activation of an "intestinal" stellate cell. METHODS: GI carcinoid tumors were collected for Q RT-PCR analysis of CTGF and TGFbeta1. Markers of stellate cell desmoplasia were identified in peritoneal fibrosis by immunohistochemistry and stellate cells cultured from fresh resected fibrotic tissue. CTGF and TGFbeta1 were evaluated using quantitative tissue array profiling (AQUA analysis) in a GI carcinoid tissue microarray (TMA) with immunostaining and correlated with clinical and histologically documented fibrosis. Serum CTGF was analyzed using a sandwich ELISA assay. RESULTS: Message levels of both CTGF and TGFbeta1 in SI carcinoid tumors were significantly increased (> 2-fold, P < 0.05) versus normal mucosa and gastric (non-fibrotic) carcinoids. Activated stellate cells and markers of stellate cell-mediated fibrosis (vimentin, desmin) were identified in histological fibrosis. An intestinal stellate cell was immunocytochemically and biochemically characterized and its TGFbeta1 (10-7M) initiated CTGF transcription response (> 3-fold, P < 0.05) demonstrated. In SI carcinoid tumor patients with documented fibrosis, TMA analysis demonstrated higher CTGF immunostaining (AQUA Score: 92 +/- 8; P < 0.05), as well as elevated TGFbeta1 (90.6 +/- 4.4, P < 0.05). Plasma CTGF (normal 12.5 +/- 2.6 ng/mL) was increased in SI carcinoid tumor patients (31 +/- 10 ng/mL, P < 0.05) compared to non-fibrotic GI carcinoids (< 15 ng/mL). CONCLUSION: SI carcinoid tumor fibrosis is a CTGF/TGFbeta1-mediated stellate cell-driven fibrotic response. The delineation of the biology of fibrosis will facilitate diagnosis and enable development of agents to obviate its local and systemic complications.

AQUA and FISH analysis of HER-2/neu expression and amplification in a small cell lung carcinoma tissue microarray.

AIMS: Most small cell lung carcinoma (SCLC) patients have metastatic disease at the time of diagnosis and are faced with poor prognosis and limited treatment options. Reports of HER-2/neu gene amplification and overexpression in this malignancy have raised the possibility of applying targeted immunotherapy with trastuzumab, the monoclonal antibody used to treat metastatic breast cancer. However, a review of the studies measuring HER-2/neu gene amplification and protein expression in SCLC reveals discordant results. The aim of the present study was to re-examine HER-2/neu expression in SCLC in relation to gene copy number using the new, highly sensitive, immunofluorescence automated quantitative analysis (AQUA) technology. METHODS AND RESULTS: Fluorescence in situ hybridization (FISH) was used to measure HER-2/neu gene copy number and amplification status and AQUA was used to measure protein expression in a series of 23 SCLC tumours on a tissue microarray. None of the 17 SCLC specimens assessable by FISH exhibited HER-2/neu gene amplification as defined by a HER-2/neu/chromosome 17 ratio = or > 2. Twelve of 17 (70.1%) SCLC samples were polysomic for chromosome 17 with corresponding increases in HER-2/neu gene copy numbers. Intermediate levels of protein expression corresponding to AQUA scores in the range of 4-24 were detected in all 23 specimens. High protein expression levels corresponding to AQUA scores up to 83, observed previously in association with gene amplification and poor prognosis in breast cancer cases, were not detected in the present study. No statistically significant association was observed between absolute chromosome 17 or HER-2/neu gene copy numbers and protein expression levels in tumour cells (P > 0.45). CONCLUSIONS: The lack of gene amplification and robust HER-2/neu protein expression in SCLC tumour cells in this series does not suggest a prominent role for the HER-2/neu gene in SCLC tumour progression and does not support the general applicability of targeted immunotherapy with trastuzumab to this malignancy.

Staging and clinical prognostic factors for small-cell lung cancer.

The two-stage system introduced by the Veterans' Affairs Lung Study Group continues to be widely utilized in small-cell lung cancer (SCLC), mainly because of its simplicity and clinical utility. Approximately one third of patients with SCLC present with limited-stage disease, which is defined as disease that can be encompassed in a tolerable radiation field. However, this definition is controversial when it is applied to the staging classification of patients with locoregionally advanced disease manifested as the presence of an ipsilateral pleural effusion, contralateral supraclavicular lymphadenopathy, or contralateral mediastinal lymphadenopathy. The more descriptive TNM system is useful for patients with disease limited to the lung, when surgical resection may be feasible; this occurs in far less than 10% of cases. As shown by clinical studies and autopsy data, metastatic disease frequently involves the liver, adrenals, bone, bone marrow, and brain. History and physical examination, complete blood count and chemistry studies, chest x-ray studies, computed tomography of the chest or upper abdomen, computed tomographic scanning or magnetic resonance imaging of the brain, and bone scans are recommended for the pretreatment evaluation of patients with SCLC. A bone marrow biopsy may be omitted for patients with normal blood counts, normal lactate dehydrogenase level, and negative result on bone scan. The use of new imaging modalities, such as magnetic resonance imaging of the bone marrow and positron emission tomographic scanning, may optimize staging evaluation. Multiple prognostic parameters have been identified for patients with SCLC, the most important of which are the stage or extent of disease, performance status, serum lactate dehydrogenase level, and male gender. Identification of risk factors for treatment-related mortality is important for the management of patients with SCLC.

Phase II trial of 9-aminocamptothecin as a 72-h infusion in cutaneous T-cell lymphoma.

PURPOSE: To evaluate the role of 9-aminocamptothecin (9-AC), a synthetic camptothecin analog, in advanced cutaneous T-cell lymphoma (CTCL). METHODS: Eligible patients had stage IIB-IV CTCL. 9-AC was infused over 72 h at a dose of 1,100 microg/m2 per day (approximately 46 microg/m2/h) every 2 weeks, with granulocyte-colony stimulating factor (G-CSF) support. RESULTS: Twelve patients received a total of 30 cycles of 9-AC. Nine patients had stage IV disease, 5 patients had circulating Sezary cells, and 2 patients had evidence of tranformation to a large cell lymphoma. Most of the patients were heavily pretreated: 10 had received prior chemotherapy (83%), 5 of whom had received 2 or more prior regimens, including a patient who had received high-dose chemotherapy, and 7 had previously received total-skin electron beam therapy. The study was prematurely terminated due to substantial toxicity. Six patients (50%) developed an indwelling central venous catheter-related infection, 5 during a period of neutropenia. Three patients died due to sepsis 4-8 weeks after their last 9-AC treatment. Two of these patients had a previous history of bacterial sepsis. Four patients (33%) developed grade IV thrombocytopenia. Two partial responses were observed (response rate 17%), but the duration of response was brief, 4-8 weeks. CONCLUSION: 9-AC at this schedule and route of administration had activity but resulted in an unacceptable rate of complicated neutropenia and septic deaths in heavily pretreated patients with advanced CTCL who are susceptible to catheter-related infections.

Rationale for non-platinum chemotherapy in advanced NSCLC.

During the past decade, five new cytotoxic drugs have been introduced that are active against non-small-cell lung cancer (NSCLC). These agents include vinorelbine (Navelbine), paclitaxel (Taxol), docetaxel (Taxotere), gemcitabine (Gemzar), and irinotecan (CPT-11, Camptosar). Used alone, these drugs display activity comparable to cisplatin. The combination of cisplatin and one of the newer drugs produces better survival than treatment with cisplatin (Platinol) alone. Randomized studies of chemotherapy regimens that include these newer drugs have demonstrated improved survival, fewer side effects, or both, compared with earlier standard combinations such as cisplatin/vindesine or cisplatin/etoposide. Docetaxel and perhaps some of the other newer drugs are of value for patients previously treated with platinum-containing regimens. Future studies should determine whether combinations of these newer drugs are superior to cisplatin-containing regimens. Although improved survival is the most important factor in defining the best regimen in non-small-cell lung cancer, additional considerations include patient tolerability, costs of administration, and the rationale for and ability to include noncytotoxic agents (such as inhibitors of signal transduction pathwriys or angiogenesis) into the therapeutic program.

Advances in chemotherapy for small cell lung cancer: single-agent activity of newer agents.

Small cell lung cancer (SCLC) is a common neoplasm with an extremely poor prognosis. Patients with extensive-stage disease have a 5-year survival rate of 1% to 2%. Identification of new active chemotherapy agents is of great importance for the development of more effective treatment for SCLC. Several new drugs that have established a role in the management of non-SCLC in the past decade are also active in SCLC. The mean response rates in untreated versus previously treated patients for these newer drugs are: 26% versus 14% for vinorelbine, 27% versus 14% for gemcitabine, 45% versus 29% for paclitaxel, 22% versus 25% for docetaxel, 39% versus 19% for topotecan, and 50% versus 16% to 24% for irinotecan. A comparison of the response rates of those agents to more established drugs (e.g., cisplatin and etoposide) suggests that the newer drugs are equally or more active in previously treated patients with SCLC. This activity is even more impressive because initial therapy during the past decade has almost always included platinum and/or an epipodophyllotoxin in the regimen. Furthermore, a recent randomized trial showed that the combination of a newer agent (irinotecan) with cisplatin was superior to a standard etoposide and cisplatin regimen in patients with newly diagnosed extensive-stage SCLC. These data support further evaluation of the newer chemotherapeutic drugs, and especially the camptothecins (irinotecan and topotecan) and the taxanes (paclitaxel and docetaxel), in the initial treatment of SCLC.

Rationale and dose-finding studies of the combination of irinotecan and a taxane on a weekly schedule.

Cisplatin (Platinol)-based chemotherapy has been the standard systemic therapy for both non-small-cell and small-cell lung cancer for the past 2 decades, though the efficacy and benefit remain modest. Recently, several novel agents have been introduced that have single-agent activity comparable to cisplatin and offer the possibility of improved therapy for lung cancer. Camptothecin and taxane derivatives are associated with both different mechanisms of action and nonhematologic toxicities, and have demonstrated additive or synergistic activity when used in combination in preclinical studies. We review pertinent clinical studies of these agents in lung cancer and present our experience in combining irinotecan (Camptosar, CPT-11) with taxanes on a weekly schedule in dose-finding and efficacy studies. When chemotherapy is delivered for 4 consecutive weeks followed by a 2-week rest, hematologic toxicity is dose limiting and most prominent during weeks 3 and 4. Dose intensification is feasible if the schedule is modified so the chemotherapy is given on days 1 and 8, with cycles repeated every 3 weeks. The most common nonhematologic toxicities remain asthenia, neuropathy, and diarrhea. Future studies will explore and better define the role of these drug combinations in the treatment of lung cancer.

Irinotecan and taxane combinations for non small-cell lung cancer.

Based on nonoverlapping toxicity profiles and at least additive cytotoxicity in preclinical models, chemo-therapy regimens have been developed that feature the combination of irinotecan and a taxane drug. In the first study, the optimal doses of paclitaxel and irinotecan were 75 mg/m2 and 50 mg/m2, respectively, when chemotherapy was administered weekly for 4 consecutive weeks, followed by a 2-week rest. The dose-limit-ing toxicity for this regimen was neutropenia, and the most prominent nonhematologic toxicities were mild diarrhea and fatigue. Pharmacokinetic studies failed to demonstrate any sequence-dependent interaction be-tween these agents on the metabolism of irinotecan or its major metabolite. This regimen has been modified, with chemotherapy given on day 1 and day 8 every 3 weeks, and is being tested further in previously un-treated advanced non small-cell lung cancer (NSCLC). In a second trial, irinotecan was combined with docetaxel on a weekly schedule. When chemotherapy was given weekly for 4 weeks, followed by a 2-week rest, the recommended doses of docetaxel and irinotecan were 35 mg/m2 and 50 mg/m2, respectively. Low-grade gastrointestinal toxicity and asthenia were the dose-limiting toxicities. The treatment schedule was modified, with chemotherapy given on days 1 and 8 of a 21-day cycle, and patients are currently being treated with docetaxel 35 mg/m2 and irinotecan 65 mg/m2. Among the 10 evaluable patients with NSCLC in this second study, there was one partial response lasting 24 weeks and four patients with stable disease, including one patient who had progressive disease on a prior paclitaxel-containing regimen. The combinations of irinotecan and a taxane on a weekly schedule are active and well tolerated and deserve further evaluation in the treatment of NSCLC.

Phase I and pharmacokinetic study of novobiocin in combination with VP-16 in patients with refractory malignancies.

PURPOSE: The coumarin antibiotic novobiocin potentiates the activity of etoposide (VP-16) in vitro by increasing intracellular accumulation of VP-16. The drug efflux pump inhibited by novobiocin appears to be distinct from both of the major proteins associated with the multidrug resistance phenotype in human cancers, the 170-kDa P-glycoprotein and the 190-kDa multidrug resistance protein. In a recent study, we found that novobiocin augmented VP-16 accumulation ex vivo in 16 of 24 fresh tumor samples at concentrations that could be achieved in vivo. Therefore, we conducted a clinical trial to determine the maximum tolerated dose and the pharmacokinetics of novobiocin when given in combination with VP-16. PATIENTS AND METHODS: Patients with refractory cancer were treated with VP-16 on days 1, 3, and 5. Antiemetics, consisting of ondansetron and dexamethasone, were given 60 minutes before the VP-16 was administered. Novobiocin was given orally 30 minutes before the VP-16, and the dose was escalated in successive groups of patients according to a standard dose escalation design. Treatment cycles were repeated every 4 weeks. Plasma concentrations of novobiocin were determined during the first treatment cycle by high-performance liquid chromatography. RESULTS: Thirty-three patients were treated for a total of 69 cycles. Eleven patients were treated with a starting dose of VP-16 of 120 mg/m2, and three of these patients experienced neutropenic fever. The dose of VP-16 was reduced to 100 mg/m2, and an additional 22 patients were enrolled. The dose of novobiocin ranged from 3 to 9 g. At a novobiocin dose of at least 5.5 g, plasma concentrations of at least 150 microM were sustained for 24 hours. Dose-limiting toxicities consisted of neutropenic fever and reversible hyperbilirubinemia. Nausea, which was a limiting toxicity in other trials of novobiocin, was well controlled with the use of serotonergic antiemetics. Diarrhea was common but mild in most patients. DISCUSSION: In previously treated patients, the recommended dose of novobiocin in this schedule is 7 g/m2/day. Novobiocin does not appear to augment the toxicity of VP-16 to the bone marrow or the gastrointestinal mucosa. Plasma concentrations of novobiocin equivalent to the levels required to modulate VP-16 in vitro are readily achievable for total but not unbound free drug.

P-glycoprotein expression and multidrug resistance in cutaneous T-cell lymphoma.

Advanced-stage cutaneous T-cell lymphoma (CTCL) is generally resistant to standard chemotherapy. Because P-glycoprotein (P-gp) has been detected in other types of resistant solid tumors, leukemias, and lymphomas, we analyzed P-gp expression in CTCL. Twenty-seven patients with CTCL and circulating Sezary cells in the peripheral blood as observed on a peripheral smear treated at the Yale Photopheresis Center between 1987 and 1993 were identified. Twenty-five of these patients had skin biopsies evaluated for expression of P-gp using JSB-1 (Accurate Chemical), MRK-16 (gift of T. Tsuruo), and UIC-2 (gift of E. Metchner). P-gp expression was considered present if immunoreactivity was noted with two of the three antibodies. Eighteen of 25 patients (72%) evaluated exhibited expression. The patients were treated with various combinations of drugs consisting of topical and systemic steroids electron beam therapy, psoralens in combination with UV light A (PUVA), systemic chemotherapy, and photopheresis before testing the tissue for P-gp expression. Treatment with systemic chemotherapy in P-gp-positive patients produced responses in 3 and no responses in 11 patients (4 were lost to follow-up). Seven patients did not express P-gp: One patient responded to treatment, five did not respond, and one patient was lost to follow-up. These results demonstrate that P-gp is frequently expressed in CTCL. P-gp expression in our study was not a useful predictor of drug resistance.

Novobiocin-induced VP-16 accumulation and MRP expression in human leukemia and ovarian carcinoma cells.

We have previously reported that novobiocin potentiates the cytotoxic activity of etoposide (VP-16) and teniposide (VM-26) in a number of experimental tumor cell lines by inhibition of the efflux of the epipodophyllotoxins by an ATP-requiring transporter. In leukemia cells from 12/19 patients and in ovarian carcinoma cells from 2/4 patients, novobiocin, in a concentration range of 150-1000 microM, increased the intracellular accumulation of VP-16 by 30-250% by inhibiting its efflux. Novobiocin did not significantly increase the intracellular concentration of VP-16 in human mononuclear bone marrow cells from two individuals with normal bone marrow, suggesting that it might be possible to selectively modulate the intracellular accumulation of the epipodophyllotoxin in tumor cells relative to normal hematopoietic tissue. Previous findings from our laboratory have provided evidence that the membrane transporter for VP-16 which is inhibited by novobiocin is distinct from the P-glycoprotein. The expression of MRP, measured by immunoblotting, was variable in novobiocin-responsive and non-responsive leukemia cells, indicating that no direct relationship existed between the modulatory activity of novobiocin on the transport of VP-16 and the expression of the MRP gene. The findings indicate that the novobiocin-sensitive VP-16 transporter is (i) present in high frequency in leukemia and ovarian carcinoma cells, and (ii) probably not the P-glycoprotein or MRP.

Dose escalation and pharmacokinetic study of irinotecan in combination with paclitaxel in patients with advanced cancer.

PURPOSE: Based on preclinical data demonstrating synergy between camptothecin analogues and taxanes, we determined the maximum tolerated dose (MTD) of irinotecan that could be given in combination with a fixed dose of paclitaxel of 75 mg/m2, when both drugs were delivered on a weekly schedule. The pharmacokinetics of this combination were explored to determine whether the sequence of administration affected the elimination of irinotecan. METHODS: For the first cycle patients with advanced cancer were treated with irinotecan given as a 90-min infusion followed immediately by paclitaxel given at a dose of 75 mg/m2 over 1 h. The sequence of drug administration was reversed in subsequent cycles for most patients. Chemotherapy was given weekly for 4 weeks, followed by a 2-week rest. In selected patients, plasma concentrations of irinotecan were determined by high-performance liquid chromatography during the first 24 h of cycle 1 and after the first dose of cycle 2 to determine whether the order of drug administration affected the elimination of irinotecan, or the toxicologic effects of the chemotherapy. RESULTS: A total of 53 cycles were delivered to 21 patients. Reversible neutropenia was dose-limiting. Suppression of the other blood cell elements was modest. There was one partial response in a man with a previously treated cholangiocarcinoma that lasted 26 weeks. Prolonged stabilization of disease (6 months or more) was observed in five of the patients (24%). At the recommended dose of irinotecan (50 mg/m2), transfusions of red cells and platelets were not required. The sequence of drug administration produced no significant differences in the pharmacokinetic parameters of irinotecan or SN-38, which were similar to the values reported when irinotecan is administered alone. The most prominent nonhematologic toxicities were mild diarrhea and fatigue. CONCLUSIONS: The recommended dose of irinotecan on this schedule is 50 mg/m2. The sequence of drug administration affects neither the elimination of irinotecan nor the chemotherapy-related toxicity. This combination is well tolerated and causes minimal clinical side effects.

Docetaxel and irinotecan, alone and in combination, in the treatment of non-small cell lung cancer.

Single-agent activity has been observed for both docetaxel and irinotecan in several solid tumors, including non-small cell lung cancer (NSCLC). Compilation of data from phase II trials of single-agent docetaxel therapy in NSCLC yielded overall response rates of 26% and a 1-year survival rate of 52%. Furthermore, a recent study that combined radiotherapy with concurrent docetaxel treatment reported an overall response rate of 77%. The most important adverse effect of docetaxel therapy is neutropenia Phase II trials of single-agent irinotecan for NSCLC patients resulted in response rates of 15% to 31%. The main toxicities were neutropenia and diarrhea. Investigators have begun to explore the efficacy of combining docetaxel and irinotecan. The results of preclinical studies suggest that schedule and order of administration may be important. A Japanese study evaluated the combination in previously untreated patients with NSCLC, and found eight partial responses in 26 patients (32%). A recent phase I study at the Mayo Clinic showed partial responses in three of five patients who received irinotecan followed by docetaxel. In a phase I study conducted at Yale Cancer Center, escalating doses of docetaxel (25 to 40 mg/m2) were given before irinotecan (50 mg/m2) for 4 weeks followed by a 2-week rest. There was one partial response among five evaluable patients with NSCLC (one of four among patients who had received no prior chemotherapy). The results of these studies suggest that the combination of docetaxel and irinotecan shows promise in the treatment of NSCLC. Irinotecan also has been used in combination with other chemotherapeutic agents. The irinotecan/etoposide combination has been less extensively evaluated but thus far appears to be associated with considerable toxicity, particularly myelosuppression, without clear therapeutic advantage. One report of the use of the triple combination of irinotecan/cisplatin/etoposide resulted in 16 partial responses in 42 NSCLC patients (38%). Like docetaxel, irinotecan has been used effectively in conjunction with radiation therapy, with partial response rates in some studies of more than 70%.

Peripheral blood progenitor cell cycle kinetics following priming with pIXY321 in patients treated with the "ICE" regimen.

PURPOSE: Treatment with hematopoietic growth factors increases the percentage of hematopoietic progenitor cells in cell cycle. Following withdrawal of certain growth factors, preclinical data suggest that there is a transient fall in the percentage of progenitor cells in cycle below the baseline, thus providing a window to administer chemotherapy with reduced risk of myelotoxicity. PATIENTS AND METHODS: Patients with histologically confirmed, previously untreated neoplasia, were treated with pIXY321 by subcutaneous injection at a dose of 375 microg/m2 twice daily (total dose 750 microg/m2/day) for seven days (days -8 to -2), followed by a two-day rest (days -1 to 0). Patients received ICE (ifosfamide, carboplatin and etoposide) on days 1 to 3. On day 4, pIXY321 was resumed until hematologic recovery. Peripheral blood was collected on days -8, -2, -1, 1, and cell cycle distribution was determined using flow cytometry. RESULTS: Twenty patients were treated in this study and received a total of 54 cycles. Partial responses were observed in three of 13 patients with non-small cell lung cancer (23 percent) and two of five patients with small cell lung cancer (40 percent). Six of 15 patients had an increased number of cells in S+G2/M on day 1 of ICE following seven days of pIXY321 and two days off (days -1 to 0). The average increase was 63 percent (range 6-253). Seven patients had a decreased number of cells in S+G2/M. The average decrease was 55 percent (range 6.3-78). There were no significant differences among the fifteen patients with regards to the observed toxicity of the chemotherapy. DISCUSSION: pIXY321 in this schedule did not consistently decrease the percentage of cycling progenitor cells in the peripheral blood. Future studies should define whether other growth factors and/or schedules can synchronize progenitor cell cycling and protect the marrow compartment from cycle specific chemotherapy.

Dose-escalation and pharmacodynamic study of topotecan in combination with cyclophosphamide in patients with refractory cancer.

PURPOSE: Based on preclinical data that demonstrated synergy between alkylating agents and topoisomerase (topo) I poisons, we determined the maximum-tolerated dose (MTD) of topotecan, using a 5 day bolus schedule, that could be given in combination with a single, fixed dose of cyclophosphamide. Pharmacodynamics of this combination were explored by analyzing biochemical effects of treatment in peripheral-blood mononuclear cells (PBMCs). PATIENTS AND METHODS: Patients with refractory cancer were treated with cyclophosphamide 600 mg/m2 on day 1, followed by topotecan given as a 30-minute infusion for 5 consecutive days. Cycles were repeated every 3 weeks. Once the MTD was defined, granulocyte colony-stimulating factor (G-CSF) was added to the regimen in an attempt to escalate further the dose of topotecan. Plasma concentrations of topotecan were determined during the first treatment cycle by high-performance liquid chromatography. PBMCs were sampled at baseline and throughout the 5-day treatment period for analysis of topo I protein concentrations and to determine drug-induced DNA fragmentation. RESULTS: Twenty-six patients were treated with topotecan at doses that ranged from 0.5 mg/m2/d to 1.2 mg/ m2/d for a total of 74 cycles. Reversible neutropenia was dose-limiting, with mild to moderate suppression of the other blood-cell elements commonly occurring. Transfusions of RBCs and platelets were required in 24% and 7% of treatment cycles, respectively. The most prominent nonhematologic toxicities were fatigue and weight loss. Compared with previously published data in which topotecan was administered alone, cyclophosphamide did not appear to alter the pharmacokinetics of topotecan. Significant increases in topo I concentration were identified in PBMCs following the administration of cyclophosphamide on day 1 and there was a significant decrease in topo 1 during the 5-day course of treatment (P < .01, sign test). DNA fragmentation as a result of drug treatment was identified in 11 of 15 (73%) cycles analyzed. CONCLUSION: For previously treated patients, the recommended dose of topotecan in this schedule is 0.75 mg/m2/d without growth factor support and 1.0 mg/ m2/d if it is administered with G-CSF. Biochemical changes in cells induced by exposure to camptothecins can be measured in vivo and these effects may have important implication in the design of combination therapies and the optimal scheduling of this class of agents.

Mechanism of technetium 99m sestamibi parathyroid imaging and the possible role of p-glycoprotein.

BACKGROUND: Localization of parathyroid glands is critical in the treatment of recurrent or persistent hyperparathyroidism. Technetium sestamibi imaging may improve localization; however, the mechanism of visualization of parathyroid tissue remains unclear. On the basis of the chemical structure of sestamibi it has been suggested that p-glycoprotein is involved in the transport of sestamibi across cell membranes. This study was designed to examine sestamibi uptake and retention and p-glycoprotein expression in normal and abnormal parathyroid tissue. METHODS: Thirty-two consecutive patients underwent 2-methoxy-isobutyl-isonitrile imaging immediately before parathyroid exploration. Tissue was obtained from normal and abnormal parathyroids and from the thyroid gland. Touch preparations gave rapid confirmation of tissue origin. Specimens were trimmed and weighed, and gamma-emission was counted. Percentage injected dose per gram of tissue was calculated. Immunohistochemistry was obtained with a battery of monoclonal antibodies to identify p-glycoprotein in parathyroid tissue submitted for permanent histologic examination. Slides were graded by a pathologist familiar with immunohistochemistry. RESULTS: Abnormal parathyroid tissue had a higher mean retention of injected dose per gram than did normal thyroid and parathyroid tissue. Immunohistochemistry revealed that abnormal parathyroid tissue expresses less p-glycoprotein. CONCLUSIONS: These results suggest that size is not the single determinant of parathyroid visualization and that p-glycoprotein expression may be involved in the mechanism of parathyroid imaging.

Trifluoperazine as a modulator of multidrug resistance in refractory breast cancer.

Overexpression of P-glycoprotein (P-gp) has been implicated as the mechanism of multidrug resistance (MDR) in a number of human cancers, including carcinoma of the breast. We conducted a clinical trial to determine whether the P-gp inhibitor, trifluoperazine, could sensitize patients with refractory breast cancer to vinblastine chemotherapy. Adult patients with histologically confirmed, refractory, advanced breast cancer were treated with vinblastine at a dose of 1.7 mg/m2 per day by continuous infusion for five consecutive days. Patients who did not respond after two cycles were subsequently treated with vinblastine plus trifluoperazine at a dose of 8 mg twice daily during the five days of chemotherapy. In patients from whom tumor samples were available, the expression of P-gp was determined by immunocytochemistry. Of 35 patients enrolled, 30 were evaluable, 2 of whom (7%) achieved a partial response to vinblastine alone. Among the 16 patients treated with vinblastine plus trifluoperazine there was one response (6%) which lasted 16 weeks. Tumor samples were available from 16 patients, and 14 (87%) were immunoreactive for P-pg. P_pg expression was detected both in the patient who responded to vinblastine plus trifluoperazine and in one of the two patients who responded to vinblastine alone. Continuous-infusion vinblastine demonstrated limited activity in this study. Furthermore, trifluoperazine did not effectively reverse established resistance to vinblastine. This failure may be related the presence of multiple mechanisms of drug resistance in the heavily pretreated population, or because ineffective concentrations of the modulator were achieved in vivo. Future studies should evaluate more effective modulators, and attempt to reverse MDR earlier in the course of treatment, before other forms of resistance can develop.