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Biomedical subjects

K R Hande

Publications and source records attributed to K R Hande.

At least 55 records · Page 3Linked to original sources

Association between increased atrial natriuretic peptide and reduced cisplatin nephrotoxicity in rats.

Plasma atrial natriuretic peptide (ANP) concentrations were monitored in two experimental models of protection from cisplatin nephrotoxicity. Sprague-Dawley rats made diabetic with streptozotocin (65 mg/kg) were protected from cisplatin-induced nephrotoxicity when compared to control rats as indicated by reduced plasma creatinine (0.49 +/- 0.02 vs. 0.9 +/- 0.06 mg/dl; P less than .001) and blood urea nitrogen concentrations (18.51 +/- 1.4 vs. 43.08 +/- 2.1 mg/dl; P less than .001). Plasma ANP was also increased with experimental diabetes (76.5 +/- 8.98 fmol/ml) vs. normoglycemic controls (43.8 +/- 8.9 fmol/ml; P less than .02). When diabetic rats were treated with insulin, the renal protection observed with the diabetic state was reversed (creatinine, 0.70 +/- .05 mg/dl); plasma ANP concentrations were also reduced (52.2 +/- 15.2 fmol/ml). Renal platinum concentrations were significantly lower in the diabetic group and the reversal of diabetic-induced renal protection with insulin was associated with increased renal platinum concentrations. In rats given a single i.p. dose of cisplatin (5 mg/kg), a reduction in cisplatin-induced nephrotoxicity was observed when 5% NaCl was the vehicle of choice compared to that seen in rats given the same dose of drug in 0.9% saline (creatinine, 0.43 +/- 0.07 with 5% NaCl vs. 0.63 +/- 0.03 with 0.09% NaCl). NaCl (5%) administration also resulted in increased plasma ANP concentrations when compared to rats receiving equivalent volumes of 0.9% NaCl (88.4 +/- 6.2 vs. 50.5 +/- 5.6 fmol/ml, respectively). These data suggest that increased endogenous ANP may be a mechanism of renal protection common to both experimental diabetes and hypertonic saline administration. Chronically increased ANP may prevent renal accumulation of platinum in the kidney.

Animals↗

Etoposide pharmacology.

Etoposide, a podophyllotoxin derivative, has demonstrated antitumor efficacy in a number of human malignancies, including lymphomas, germinal tumors, and lung cancer (especially small cell). Etoposide's antineoplastic activity is achieved through DNA strand breakage, which likely results from the formation of a complex involving drug, DNA, and the DNA unwinding enzyme, topoisomerase II. The drug's steady state volume of distribution ranges from 5 to 17 L/m2, and it is highly bound to plasma protein with an average free plasma fraction of 6%. A number of etoposide metabolites have been confirmed or postulated. Several cell lines have been shown to acquire resistance to etoposide through membrane transport changes. Considerable intrapatient variability exists in pharmacokinetic parameters following intravenous (IV) and oral dosing. Approximately 30% to 40% of unchanged IV drug is excreted in the urine, whereas biliary excretion appears a minor route of drug elimination. The bioavailability of oral etoposide averages 50%, although wide variability exists both among and within different patients. Bioavailability decreases as the dose of oral etoposide is increased. Several recent studies have attempted to correlate etoposide plasma concentrations with toxicity (primarily myelosuppression) in hopes of using this information to optimize drug dosing.

Etoposide↗

Neoadjuvant cisplatin plus vinblastine chemotherapy in locally advanced non-small cell lung cancer.

Twenty-eight patients with locally advanced, unresectable non-small cell lung cancer (NSCLC) received neoadjuvant chemotherapy with cisplatin (120 mg/m2 on days 1 and 29) and vinblastine (4 mg/m2 weekly for 6 weeks). At the completion of induction chemotherapy, all patients were assessed for resectability. Those patients judged to be resectable underwent thoracotomy. All remaining patients received thoracic radiation therapy (5500 cGy) followed by additional chemotherapy in those patients responding to neoadjuvant treatment. There were 15 partial responses to neoadjuvant chemotherapy for an overall response rate of 54% (95% confidence interval, 36% to 71%). Only five partially responding patients (18%) were thought to have had sufficient tumor regression to allow for a potentially curative resection. However, a complete resection was done in only two patients. Overall median survival was 12 months (range, 4 to 72 months) with 1-year, 2-year, and 3-year survival rates of 54%, 39%, and 11%, respectively. The primary toxicity associated with neoadjuvant chemotherapy was moderate to severe (Eastern Cooperative Oncology Group Grade 3 or 4) nausea and emesis in 25% of patients. Hematologic toxicity was relatively modest; only one patient had Grade 4 leukopenia (less than 1000/microliter). Fever and neutropenia were uncommon, and there were no documented septic episodes or treatment-related deaths. Compared with historic controls treated with radiation therapy alone, cisplatin-based neoadjuvant chemotherapy appeared to improve the median and long-term survival of Stage III NSCLC patients modestly.

Adenocarcinoma↗

Current status of etoposide in the management of small cell lung cancer.

Etoposide is a schedule-dependent drug with excellent activity against small cell lung cancer (SCLC). Single-agent etoposide achieves overall response rates ranging from 15% to 84%, depending on the schedule of drug administration and the characteristics of the treated population. The route of etoposide administration (intravenous versus oral) has little impact on response rate, provided appropriate dose adjustments are made for oral therapy. In combination with other active agents, etoposide has proven particularly effective in the management of SCLC. Etoposide can be substituted for doxorubicin or vincristine in the cyclophosphamide, doxorubicin, and vincristine (CAV) regimen without loss of efficacy. The etoposide and cisplatin (EP) combination is thought to be synergistic and has proven to be an effective salvage regimen for CAV failures. A regimen that alternates CAV and EP has been found by some investigators to be modestly more effective against SCLC than CAV alone; however, EP alone may be as useful as an alternating regimen. Most studies to date have demonstrated that EP induction is at least as effective as any other standard induction regimen. However, EP has the potential advantage of being more easily integrated with thoracic radiation therapy (RT). This is particularly important in limited-disease patients: two recent pilot studies employing EP induction with hyperfractionated thoracic RT yielded 2-year survival rates of greater than 50%. These promising results are being evaluated further in an ongoing Phase III trial in the United States. The available data indicate that etoposide is one of the most active agents against SCLC and therefore should be included as a component of induction therapy in all patients. New schedules of etoposide administration warrant further study.

Antineoplastic Combined Chemotherapy Protocols↗

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy.

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.

Acute Disease↗

Kinetics of N-[(4-chlorophenyl)amino]carbonyl-2,3-dihydro-1H-indene-5-sulfonamide (LY186641) in humans.

The metabolism and disposition of LY186641, a diarylsulfonylurea with antineoplastic activity identified in preclinical tests, was determined in 21 patients who received 23 courses of orally administered drug. A linear correlation was found between the dose of drug administered and LY186641 peak plasma concentrations and LY186641 area under the curve measurements. Clearance (135 +/- 36 ml/h/m2), terminal half-life (31 +/- 11 h), and volume of distribution (10.2 +/- 2.8 liters) were independent of drug dose. No LY186641 was excreted in urine. Hydroxy and keto metabolites of LY186641 were identified in plasma and urine samples. Urinary excretion of these metabolites during the initial 48 h following drug administration accounted for 20% of LY186641 disposition. Plasma half-life of the hydroxy and keto metabolites was longer than that of parent drug (3.3 and 3.1 days, respectively). Plasma concentrations of parent drug correlated with the presence of methemoglobinemia, the dose-limiting toxicity found with LY186641.

Administration, Oral↗

The effect of cimetidine on cyclophosphamide metabolism in rabbits.

Six female rabbits were given 20 mg/kg cyclophosphamide (containing 100 microCi [3H-chloroethyl]-cyclophosphamide) alone or 1 h following 100 mg/kg cimetidine. Serial plasma and urine specimens were collected and levels of cyclophosphamide and its metabolites (4-hydroxycyclophosphamide, 4-ketocyclophosphamide, phosphoramide mustard, and carboxyphosphamide) were measured. 4-Ketocyclophosphamide was the major metabolite present in rabbit plasma and urine, with lesser amounts of 4-hydroxycyclophosphamide, carboxyphosphamide, and phosphoramide mustard also being identified. Cimetidine pretreatment resulted in prolongation of cyclophosphamide's half-life from 24.3 +/- 7.3 to 33.5 +/- 9.5 min (mean +/- SD; P = 0.036) but did not significantly alter the AUC0-8 h for the latter drug. Cimetidine pretreatment resulted in a significantly greater AUC0-8 h for 4-hydroxycyclophosphamide (189.4 +/- 77 vs 364.6 +/- 126.7 mumol min/l-1; P = 0.016) as compared with control values. A higher AUC0-8 h value for phosphoramide mustard (53.7 +/- 69.2 vs 95.7 +/- 34.7 mumol min/l-1) was also observed after cimetidine dosing but the difference was not significant (P = 0.21). Kinetics of 4-ketocyclophosphamide and carboxyphosphamide were not significantly affected by cimetidine treatment. Cimetidine was added to hepatic microsomes isolated from phenobarbital-treated rabbits; it did not inhibit cyclophosphamide's metabolism in vitro, suggesting that its in vivo effect may be mediated through mechanisms other than cytochrome P-450 inhibition. Cimetidine pretreatment increases exposure to cyclophosphamide and its major activated metabolite, 4-hydroxycyclophosphamide. Potentiation rather than inhibition of cyclophosphamide's pharmacodynamic effect is to be predicted when cimetidine is given concomitantly with the former. Alterations in hepatic blood flow or mechanisms other than microsomal inhibition by cimetidine may explain this potentiation.

Animals↗

Prolonged administration of oral etoposide in patients with relapsed or refractory small-cell lung cancer: a phase II trial.

Twenty-two patients with recurrent small-cell lung cancer (SCLC) were treated with single-agent etoposide 50 mg/m2/d by mouth for 21 consecutive days. Eleven patients had received previous chemotherapy with cyclophosphamide, doxorubicin, and vincristine (CAV) or etoposide (CAE) or both (CAVE). Four of the latter patients also received salvage treatment with cisplatin and etoposide (EP). Nine patients had been treated with EP as induction therapy, while two patients had received high-dose cyclophosphamide, etoposide and cisplatin (HDCEP). Altogether, 18 patients had received previous intravenous etoposide. The median time off chemotherapy was 4.5 months (range, 1 to 28.9 months). Ten patients (45.5%; 95% confidence interval [CI], 27% to 65%) achieved a complete or partial response. Responses were most common in patients who had responded to previous chemotherapy and who had not received any treatment in the 90 days before initiation of oral etoposide. Median response duration was 4 months (range, 1.5 to 9.5 months) and median survival was 3.5+ months (range, 1.0 to 15+ months). Leukocyte and platelet nadirs were 1,800/microL and 160,000/microL, respectively, during cycle 1 of treatment and occurred between days 21 and 28. Overall, total leukocyte count decreased to less than 1,000/microL during 10 of 56 cycles (18%). Five patients required six hospitalizations for neutropenia and fever. There were two toxic deaths due to sepsis. Platelet counts less than 50,000/microL occurred in 14 cycles (25%). Alopecia developed in all patients; gastrointestinal toxicity was uncommon. This schedule of etoposide administration warrants further study in combination with other active agents in previously untreated patients with SCLC.

Administration, Oral↗

Etoposide kinetics in patients with obstructive jaundice.

The kinetics and urinary excretion of etoposide and etoposide glucuronide were determined in 11 patients with obstructive jaundice (bilirubin greater than 2.0 mg/dL) and in 23 patients with normal renal and hepatic function. Mean (+/- SE) measurements of clearance (24.5 +/- 2.06 v 26.5 +/- 2.05 mL/min/m2), half-life (5.7 +/- 0.5 v 6.4 +/- 0.5 hours), and volume of distribution (12.4 +/- 1.1 v 13.7 +/- 1.6 L/m2) were not significantly different in patients with jaundice when compared with controls. Similarly, etoposide kinetics in three patients determined during a period of hyperbilirubinemia were not different from measurements made in the same patients following resolution of their obstructive jaundice. In patients with jaundice, 46% of an administered etoposide dose was excreted in the urine as etoposide compared with 35% in controls (P = .15). Urinary excretion of etoposide glucuronide accounted for 29% of an administered etoposide dose in control patients and 15% in those with hepatic obstruction (P = .03). Biliary etoposide excretion measured in four patients with T-tubes was insignificant (less than 2.0% of an administered dose). The calculated renal clearance of etoposide was 11.5 mL/min/m2 in patients with jaundice and 10.4 mL/min/m2 in controls (P = .53). Respective metabolic clearance was 4.9 and 6.9 mL/min/m2 in these two study groups (P = .13). Although hepatic metabolism of etoposide may be slightly decreased in patients with obstructive jaundice, a modest increase in renal etoposide excretion appears to compensate for this change, so that total clearance is similar in the patients with jaundice when compared with controls. No etoposide dose reductions appear to be needed in treating patients with obstructive jaundice who have normal renal function.

Biliary Tract↗

Phase I clinical study of N-[(4-chlorophenyl)amino]carbonyl-2,3-dihydro-1H-indene-5-sulfonamide (LY186641).

Between February 1987 and July 1988, 45 patients with advanced refractory cancer were treated with LY186641, a diarylsulfonylurea that has shown a broad spectrum of activity in preclinical testing. Patients received a weekly p.o. dose of LY186641 for 6 consecutive weeks; responding and stable patients continued weekly therapy until progression occurred. Using a standard phase I study design, the first three patients received LY186641 at 30 mg/m2 week; the dose was escalated in subsequent patients until dose-limiting toxicity occurred. Methemoglobinemia was the major toxicity observed and was dose related. Methemoglobin levels peaked approximately 24 h after LY186641 was administered and fell to low levels after 48 h. Six patients developed fatigue, cyanosis, and dyspnea associated with serum methemoglobinemia levels of greater than 20%; four of these patients were subsequently removed from the study. Hemolytic anemia was also observed but was clinically significant in only 10 patients. Other side effects were mild and infrequent. The maximum tolerated dose of LY186641, when given at this schedule, was 2550 mg/m2/week. No objective tumor responses were observed.

Antineoplastic Agents↗

Chemotherapy of advanced non-small-cell lung cancer: a randomized trial of three cis-platin-based chemotherapy regimens.

One hundred fifty-two patients with locally advanced or metastatic non-small-cell lung cancer were randomized to receive treatment with one of three cis-platin-containing chemotherapy regimens: vindesine/cis-platin, etoposide/cis-platin, or vindesine/etoposide/cis-platin. Following an 8-week induction course of treatment, patients were evaluated for response; responders continued to receive monthly chemotherapy. All patients were followed until death. Response rates for the three regimens were 10%, 6%, and 24%, respectively; the cis-platin/vindesine/etoposide regimen produced more responses than did either cis-platin/etoposide or cis-platin/vindesine (p less than 0.05). However, median survival was not improved with the three-drug regimen, and myelosuppression produced by this regimen was worse. The 20-week median survival for the entire group suggests that these treatments had no impact on survival. None of these regimens can be recommended for routine treatment of patients with advanced non-small-cell lung cancer. The addition of vindesine did not make a significant impact in response rate or overall survival in this study.

Actuarial Analysis↗

Combined small-cell and non-small-cell lung cancer.

Nine (2%) of 429 small-cell lung cancer (SCLC) patients seen at Vanderbilt University between 1977 and 1983 had a combined subtype SCLC at diagnosis (ie, small-cell carcinoma plus squamous cell or adenocarcinoma). Staging procedures and chemotherapy treatment were uniform for all 429 patients. The diagnosis of combined histology was established via bronchoscopy (six patients), needle aspiration biopsy (one), lymph node biopsy (one), and thoracotomy (one). The clinical characteristics of the combined subtype patients were similar to patients with other subtypes of SCLC (ie, there were no differences in median age, sex, performance status, and stage of disease). However, patients with a combined subtype histology had a higher incidence of peripheral lesions on chest x-ray (56% v 14%, P less than .001) and a lower median lactate dehydrogenase (LDH) (301 IU/L v 341 IU/L, P = .0002) at diagnosis. The overall response to chemotherapy (57% v 78; P = .5) and the median survival (8 months v 10 months; P = .4) of the combined subtype patients were similar to patients with other subtypes of SCLC. Two (22%) combined histology patients survived greater than or equal to 5 years. Both had had surgical resection in addition to chemotherapy. These data suggest that the combined subtype of SCLC is clinically similar to pure SCLCs and that surgery may play a prominent role in the management of these tumors. The possibility of a combined histology tumor should be considered in patients thought to have SCLC on the basis of limited biopsy material, such as a needle aspiration or bronchial biopsy, and when the primary lesion is peripherally located on chest x-ray.

Adenocarcinoma↗

Uptake and intracellular distribution of doxorubicin metabolites in B-lymphocytes of chronic lymphocytic leukemia.

The toxicity of doxorubicin metabolites was evaluated on lymphocytes of B-cell chronic lymphocytic leukemia. Only doxorubicinol was found to be cytotoxic for these lymphocytes, whereas exposure to aglycones at concentrations as high as 5 microM for 1 h had no effect on the proliferative capacity of these cells. After exposure of cells to isomolar concentrations of doxorubicin or its metabolites, uptake/retention of doxorubicinol was 23% of doxorubicin, and uptake/retention of aglycones was 5 to 13% of doxorubicin. Seventy to 90% of doxorubicin and 60 to 90% of doxorubicinol taken up/retained by the cells were detected in the cell nuclear fraction, whereas only 20 to 40% of the aglycones were localized in the cell nucleus. Cytotoxicity of metabolites was generally related to the proportion of drug taken up/retained by the cells and localized to the nuclei. The low uptake and nuclear localization may be at least partially responsible for the lack of cytotoxicity of aglycones on B-lymphocytes from chronic lymphocytic leukemia.

B-Lymphocytes↗

The influence of ranitidine on the pharmacokinetics and toxicity of doxorubicin in rabbits.

The influence of ranitidine on the pharmacokinetics and toxicity of doxorubicin was studied in six female New Zealand white rabbits. Plasma pharmacokinetic data were first obtained from rabbits given 3 mg/kg doxorubicin. After 1 month, the same rabbits were treated with ranitidine, 2.5 mg/kg or 25 mg/kg, before and during doxorubicin administration. The plasma doxorubicin assays to determine pharmacokinetic parameters were repeated. Drug toxicity was evaluated using complete blood counts, and hepatic function was measured using a 14C-aminopyrine breath test. High-dose ranitidine increased the total exposure to doxorubicin (area under the curve of doxorubicin alone = 1.44 +/- 0.88 microM.h/ml vs 4.49 +/- 2.35 microM.hr/ml for doxorubicin given with high-dose ranitidine; P = 0.06). Low-dose ranitidine did not alter doxorubicin pharmacokinetics. Exposure to doxorubicinol was altered by either high-dose or low-dose ranitidine. 14C-Aminopyrine half-life was altered by a ranitidine dose of 25 mg/kg (aminopyrine half-life after placebo control = 97 +/- 6 min as against aminopyrine half-life after ranitidine = 121 +/- 7 min; mean +/- SEM; P less than 0.02). Low-dose ranitidine did not exacerbate doxorubicin-induced myelosuppression. High-dose ranitidine enhanced doxorubicin-induced erythroid suppression while sparing the myeloid series. At cytochrome P-450-inhibitory doses, ranitidine's effects upon doxorubicin plasma pharmacokinetics are similar to those previously seen with cimetidine. These changes did not appear to alter drug detoxification and are not related to microsomal inhibition of doxorubicin detoxification. Low doses of ranitidine do not alter doxorubicin plasma pharmacokinetics or toxicity in rabbits.

Aminopyrine↗

Non-Hodgkin's lymphoma of the gastrointestinal tract: an analysis of clinical and pathologic features affecting outcome.

Clinical and histopathologic data from 87 patients with primary non-Hodgkin's lymphoma of the gastrointestinal (GI) tract diagnosed between 1974 and 1984 were reviewed. B-cell lymphomas of intermediate- or high-grade histology constituted 78% of lesions. Stage of disease varied with histologic grade, with a preponderance of advanced disease (stages IIIE and IV) in patients with low-grade lymphoma (15 of 21) (71%), compared with higher grade lesions (38%, P = .01). Among patients with nonlocalized (stages IIE through IV) lymphoma of intermediate- or high-grade histology, surgical resection of the primary focus afforded a higher rate of complete remission (CR) (70% v 50%) and sustained CR (61% v 21%, P = .04) after cytotoxic therapy compared with the nonresected cohort. The median survival in the resected group was 51 months + compared with 13 months in the nonresected patients (P = .012). Differences in outcome were attributable to a high risk of treatment-related complications (perforation and/or hemorrhage) (43% v 0%, P = .001) and local relapse (29% v 4%, P = .05) in nonresected individuals. Life-threatening local complications were not observed in patients with low-grade lymphoma managed solely with medical therapy. Histologic findings from surgically staged patients identified presence of extravisceral disease and intermediate- or high-grade tumor histology as features predictive of transmural invasion, enabling potential identification of patients who might be optimally managed by resection of the primary GI focus before initiation of cytotoxic therapy.

Adolescent↗

Effect of allyl alcohol-induced sublethal hepatic damage upon doxorubicin metabolism and toxicity in the rabbit.

A model of hepatic dysfunction in vivo has been developed in rabbits to determine the effects of sublethal hepatocellular necrosis upon doxorubicin pharmacology. Eight New Zealand white rabbits were given 3 mg/kg doxorubicin i.v. Plasma doxorubicin and metabolite pharmacokinetics were determined and toxicity assessed by nadir complete blood counts. Hepatic function was assessed by the pulmonary excretion rate of 14CO2 from [14C]aminopyrine. Hepatocellular necrosis was produced by i.v. injection of 1.35 mg/kg of a 2% allyl alcohol solution. Doxorubicin administration and pharmacokinetics were repeated. Doxorubicin enhances the hepatotoxicity of allyl alcohol. Hepatocellular necrosis does not alter the plasma pharmacokinetics of doxorubicin but does increase the plasma exposure of doxorubicinol. Doxorubicin-induced myelosuppression is enhanced by allyl alcohol pretreatment. These data suggest that in circumstances of reduced hepatocellular volume or acute hepatocellular necrosis, a key plasma marker of doxorubicin-induced acute toxicity may be doxorubicinol.

1-Propanol↗

In vitro pharmacodynamic evaluation of VP-16-213 and implications for chemotherapy.

VP-16-213 (Etoposide) is an active antineoplastic agent which has undergone extensive evaluation of clinical dose escalation. To corroborate a putative dose-response relationship, we studied, in a modified clonogenic assay, various doses and durations of exposure. VP-16-213 at doses of 0.01, 0.05, 0.10, 0.50, 1.0, 5.0, and 10.0 micrograms/ml, each with exposure durations of 1, 3, 18, and 30 h, was studied in vitro against two human tumor cell lines, MOLT and 9812. The doses and durations of exposure were chosen to approximate some of the pharmacokinetic values achievable in either standard-dose or high-dose clinical studies. The results, summarized as linear regression lines, demonstrate with statistical significance (p less than 0.03) that there is correlation between dose and cytotoxicity and between dose X duration of exposure (representing the area under the concentration-time curve) and cytotoxicity. Our in vitro data thus support the concept of intensive use of VP-16-213 to maximize antitumor activity. However, how best to accomplish the manipulation of dose and duration of exposure is not yet clear and will be the subject of future clinical investigations.

Carcinoma, Bronchogenic↗