Phase I trial of outpatient weekly docetaxel, carboplatin and concurrent thoracic radiation therapy for stage III unresectable non-small-cell lung cancer: a Vanderbilt cancer center affiliate network (VCCAN) trial.

PURPOSE: Docetaxel, an active agent for non-small cell lung cancer (NSCLC), has demonstrated activity as a radiosensitizer in numerous pre-clinical studies. We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLT) of weekly Docetaxel, Carboplatin with concurrent thoracic radiation therapy (TRT) in patients with unresectable stage III NSCLC. PATIENTS AND METHODS: In this phase I clinical trial, Docetaxel was administered weekly as a 1-h intravenous infusion for 6 weeks with a starting dose of 20 mg/m(2). Docetaxel doses were escalated by 10 mg/m(2) increments in successive cohorts of three patients. DLT was defined as grade >or=3 nonhematologic and hematologic toxicity according to RTOG toxicity criteria. Once the DLT of Docetaxel alone was reached, weekly Carboplatin (AUC 2) was added at a DLT-2 dose of Docetaxel (two dose levels below that of dose limiting toxicity). Docetaxel doses were again escalated at 10 mg/m(2) increments in successive cohorts of three new patients to define further DLT and MTD of Docetaxel/Carboplatin with TRT. TRT was administered to the primary tumor and regional lymph nodes (40 Gy) followed by a boost to the tumor (20 Gy). RESULTS: Fifteen patients were entered onto this study with Docetaxel alone through three dose escalations (from 20 to 40 mg/m(2) weekly). The DLT of weekly Docetaxel/TRT was esophagitis and the MTD was 30 mg/m(2) per week for 6 weeks. Nine more patients were added with the Docetaxel/Carboplatin/TRT regimen. The DLT of weekly Docetaxel/Carboplatin with TRT was esophagitis and the MTD of Docetaxel was 20 mg/m(2) per week with weekly Carboplatin (AUC 2). There were 2 complete responses and 13 partial responses in 25 evaluable patients (RR 60%). CONCLUSIONS: This combination regimen has activity with manageable toxicity in patients with stage III NSCLC. A phase II study is planned to define activity.

A randomized Phase II trial in patients with carcinoma of an unknown primary site.

BACKGROUND: Current therapy for patients with carcinoma of an unknown primary site (CUP) is inadequate. To develop less toxic and more effective therapies for patients with CUP, a multicenter, randomized, Phase II study was conducted. Patients with CUP received either carboplatin and etoposide (CE) or a combination of paclitaxel, 5-fluorouracil, and leucovorin (TFL). METHODS: Patients randomized to Arm A received paclitaxel, 175 mg/m(2), intravenously over 3 hours on Day 1 followed by leucovorin, 300 mg, over 30-60 minutes and 5-fluorouracil, 350 mg/m(2), both intravenously on Days 1-3. Patients randomized to Arm B received etoposide, 100 mg/m(2), intravenously on Days 1-3 and carboplatin at an area under the curve of 6 on Day 1 only. The cycles in both treatment arms were repeated every 28 days. Patients were followed for tumor response, survival, and toxicity. RESULTS: Thirty-four patients were enrolled, 32 of whom were evaluable for response. An identical overall response rate of 19% (95% confidence interval, 4-45%) was noted in each treatment arm. The median survival for the entire study population was 194 days. The median survivals observed in Arm A and Arm B were 251 days and 194 days, respectively (P = 0.91 [difference not significant]). Hematologic toxicity on Arm B was considerable with 29% of the patients developing neutropenia and fever. Toxicity on Arm A was modest. CONCLUSIONS: In this randomized Phase II trial, CE and TFL appeared to have modest activity in CUP patients, with response rates similar to those reported with previously described chemotherapy regimens. Toxicity with CE was more severe than expected, although TFL was found to be well tolerated.

Weekly irinotecan and concurrent radiation therapy for stage III unresectable NSCLC.

In preclinical studies, the topoisomerase I inhibitor irinotecan (Camptosar, CPT-11) has demonstrated activity as a radiosensitizer, probably due to its ability to inhibit potentially lethal radiation damage repair. We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLT) of weekly irinotecan with concurrent thoracic radiation therapy for patients with unresectable stage III non-small-cell lung cancer. For this study, 13 patients received three dose escalations (from 30 to 40 to 50 mg/m2/wk). At the first dose level, one patient developed grade 5 esophagitis. Accrual was expanded to seven patients. None of the remaining six patients developed esophagitis. At the second dose level (40 mg/m2/wk), the worst toxicity, which developed in one patient, was grade 2 esophagitis. At the third dose level (50 mg/m2/wk), two of three patients developed grade 4 nausea and vomiting; grade 3 or 4 esophagitis also occurred in two patients. Of the 12 evaluable patients, seven achieved a partial response, for an overall response rate of 58%. In conclusion, nausea, vomiting, and esophagitis appear to be the principal DLTs of concurrent weekly irinotecan and thoracic radiation in the outpatient setting. The MTD of concurrent weekly irinotecan with thoracic radiation therapy appears to be 40 mg/m2 weekly for 6 weeks. To confirm the MTD of this combination, this study is still open to accrual at the second dose level (40 mg/m2) in combination with carboplatin.

A phase II study of paclitaxel, carboplatin, and hyperfractionated radiation therapy for locally advanced inoperable non-small-cell lung cancer (a Vanderbilt Cancer Center Affiliate Network Study).

PURPOSE: We conducted a prospective phase II study to determine the response rate, toxicity, and survival rate of concurrent weekly paclitaxel, carboplatin, and hyperfractionated radiation therapy (paclitaxel/carboplatin/HFX RT) followed by 2 cycles of paclitaxel and carboplatin for locally advanced unresectable non-small cell lung cancer (NSCLC). The weekly paclitaxel and carboplatin regimen was designed to optimize the radiosensitizing properties of paclitaxel during the concurrent phase of treatment. METHODS AND MATERIALS: Forty-three patients with unresectable stage IIIA and IIIB NSCLC from the Vanderbilt Cancer Center and Affiliate Network (VCCAN) institutions were entered onto the study from June 1996 until May 1997. Weekly intravenous (IV) paclitaxel (50 mg/m(2)/l-hour) and weekly carboplatin (AUC 2) plus concurrent hyperfractionated chest RT (1.2 Gy/BID/69.6 Gy) were delivered for 6 weeks followed by 2 cycles of paclitaxel (200 mg/m(2)) and carboplatin (AUC 6). RESULTS: Forty-two patients were evaluable for response and toxicities. Three patients achieved a complete response (7.2%) and 30 patients achieved a partial response (71.4%), for an overall response rate of 78.6% [95% C.I. (66.2%-91.0%)]. The 1- and 2-year overall and progression-free survival rates of all 43 patients were 61.6% and 35% respectively, with a median survival time of 14.3 months. The median follow-up time was 14 months. Esophagitis was the principal toxicity. Grade 3 or 4 esophagitis occurred in 11 patients (26%). There was an incidence of 7% grade 3 and 9.5% grade 4 pulmonary toxicities. CONCLUSIONS: Weekly paclitaxel, carboplatin, plus concurrent hyperfractionated RT is a well-tolerated outpatient regimen. The response rate from this regimen is encouraging and appears to be at least equivalent to the more toxic chemoradiation trials. These findings warrant further clinical evaluation of weekly paclitaxel/carboplatin/HFX RT in a phase III study.

A phase I trial of outpatient weekly docetaxel and concurrent radiation therapy for stage III unresectable non small-cell lung cancer: a Vanderbilt Cancer Center Affiliate Network (VCCAN) Trial.

Docetaxel has demonstrated activity as a radiosensitizer in numerous preclinical studies, probably due to its role as a cell cycle synchronizer for the G2/M radiosensitive phase of the cell cycle. We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLT) of docetaxel with concurrent thoracic radiation therapy (TRT) to patients with unresectable stage III non small-cell lung cancer (NSCLC). Fifteen patients were entered into this study. Docetaxel was administered as a 1-hour intravenous (I.V.) infusion, repeated every week for 6 weeks with starting dose of 20 mg/m2. Doses were escalated in 10 mg/m2 increments in successive cohorts of three new patients, if tolerated. Unacceptable toxicity was defined as grade = 3 nonhematologic or hematologic toxicity according to Eastern Cooperative Oncology Group (ECOG) toxicity criteria. TRT was administered to the primary tumor and regional lymph nodes (40 Gy) followed by a boost to the tumor (20 Gy). At the first dose level (20 mg/m2/week), one patient developed grade 4 hyperglycemia and accrual was expanded to five patients. At the second level (30 mg/m2/week), two out of six patients developed grade 3 esophagitis. At the third level (40 mg/m2/week), two out of four patients developed grade 3 esophagitis and one patient developed grade 3 pulmonary toxicity. The weekly docetaxel MTD with concurrent radiation therapy (RT) was found to be 30 mg/m2. The DLT was esophagitis and pulmonary toxicity. Other toxicities encountered included skin reaction, nausea and vomiting, as well as diarrhea. Additionally, there were no treatment-related mortalities or late-occurring toxicities. Esophagitis was the principal DLT of concurrent weekly docetaxel and thoracic radiation in the outpatient setting. The MTD of concurrent weekly docetaxel with TRT is 30 mg/m2 weekly for 6 weeks. This study is still open to accrual with weekly docetaxel and TRT in locally advanced NSCLC patients.

Paclitaxel, 5-fluorouracil, and leucovorin (TFL) in the treatment of metastatic breast cancer.

To assess the activity of paclitaxel in combination with 5-fluorouracil (5-FU) and leucovorin in breast cancer, a phase II trial was conducted in women with metastatic disease. Toxicity, response rate, median survival, median duration of response, and median time to disease progression were measured. Between January 1994 and May 1996, 47 patients with metastatic breast cancer and an Eastern Cooperative Oncology Group (ECOG) performance status (PS) < or = 2 who had previously been treated with chemotherapy received 175 mg/m2 paclitaxel over 3 hours on day 1. After paclitaxel administration, 300 mg intravenous (i.v.) leucovorin over 30 minutes was administered followed by 350 mg/m2 i.v. push 5-FU. Both 5-FU and leucovorin were given on days 1-3. Treatment was repeated every 28 days for a minimum of 6 cycles per patient. Two (4%) patients had a complete response and 21 (45%) patients had a partial response for an overall response rate of 49% (95% confidence interval: 35%-63%). The median survival was 17.7 months, median duration of response was 8.6 months, and median time to disease progression was 6.3 months. There was no statistical difference in survival or time to progression between anthracycline-naive, anthracycline-sensitive, and anthracycline-resistant patients. Nine (19%) patients had grade 3 or 4 neutropenia, and no patient required blood or platelet transfusion. The most frequently observed nonhematologic toxicities were arthralgia and myalgia. Pharmacokinetic data were obtained on 19 patients. Responders had higher peak plasma concentrations of paclitaxel than nonresponders (4.46 vs. 2.9 micrograms/mL; P = 0.02). Paclitaxel/5-fluorouracil/leucovorin is an active, well-tolerated regimen for patients with metastatic breast cancer.

Treatment of poor-prognosis extensive disease small-cell lung cancer with an all-oral regimen of etoposide and cyclophosphamide - a Southwest Oncology Group clinical and pharmacokinetic study.

PURPOSE: An all-oral regimen of etoposide and cyclophosphamide was developed for use in poor-prognosis extensive disease small-cell lung cancer. Limited pharmacokinetic sampling was used to derive a pharmacodynamic model predictive of myelosuppression early in the course of therapy. PATIENTS AND METHODS: Eligible patients were chemotherapy-naive and had extensive disease small-cell lung cancer with either SWOG performance status 2 or serum albumin <3.5 g/dl. The first cohort (n = 18) received etoposide orally at 50 mg daily and cyclophosphamide orally at 50 mg daily days 1-14 every 28 days. Due to good hematologic tolerance, the second cohort (n = 39) received both agents orally at 50 mg twice daily days 1-14 every 28 days. Plasma etoposide levels were determined in samples drawn at baseline, and at 1 h, 2 h, and 23.5 h (trough) after the first dose. Linear regression analysis was used to determine pharmacokinetic and demographic parameters predictive of myelosuppression. RESULTS: A total of 173 treatment cycles were delivered. Patients on the daily regimen had a 22% response rate (complete and partial), a 22% unconfirmed response rate, and a 5-month median survival, while patients on the twice-daily regimen had a 28% response rate (complete and partial), a 13% unconfirmed response rate, and a 7-month median survival. Granulocytopenia and alopecia were the most common toxicities seen. Significant granulocytopenia could be predicted for the twice-daily regimen according to the formula ln(AGC nadir)=7.80 - 1.88(trough), with an increased incidence of granulocytopenia if the etoposide trough value was >/=1.49 microg/ml. CONCLUSION: Oral etoposide and oral cyclophosphamide given days 1-14 every 28 days is well tolerated and results in an acceptable response rate and median survival in poor-prognosis (poor performance status or low serum albumin) extensive disease small-cell lung cancer. A trough etoposide level obtained within 24 h of starting therapy can predict severe granulocytopenia.

Clinical applications of anticancer drugs targeted to topoisomerase II.

Agents which 'poison' the enzyme topoisomerase II, have proven to be useful drugs for cancer treatment. Six antineoplastic drugs, which target topoisomerase II (doxorubicin, daunorubicin, idarubicin, mitoxantrone, etoposide and teniposide) are currently approved for clinical use in the United States. In this paper, the strategies and goals of cancer chemotherapy are summarized for the non-clinician. The use, pharmacology and toxicity of each of the six currently approved topoisomerase II inhibiting agents are reviewed.

Pharmacokinetics of an intravenous-oral versus intravenous-mesna regimen in lung cancer patients receiving ifosfamide.

PURPOSE: To compare the pharmacokinetics of the approved I.V. (intravenous) mesna regimen and an investigational I.V.-oral regimen that could be used in outpatients who receive ifosfamide. PATIENTS AND METHODS: The I.V. regimen consisted of three I.V. mesna doses given at 0, 4, and 8 hours after ifosfamide administration. The investigational regimen included an I.V. mesna dose given concurrently with ifosfamide, followed 2 and 8 hours later by oral administration of mesna tablets. I.V. and oral mesna doses equaled 20% and 40%, respectively, of the ifosfamide dose. The study subjects were 12 lung cancer patients who received ifosfamide 1.2 g/m2 daily for 5 days. The patients were randomized to receive either the I.V.-oral or I.V. mesna regimen on day 1, followed by crossover to the other regimen on days 2 through 5 of ifosfamide treatment. The urinary profiles of mesna and dimesna excretion were determined on days 1, 2, and 5; pharmacokinetic parameters for blood samples were determined only on day 5. RESULTS: During the first 12 hours after ifosfamide administration, the amount of mesna excreted and the profile of urinary mesna excretion was similar for both regimens; however, the I.V.-oral regimen showed less fluctuation in the excretion rate and higher trough values. During hours 12 to 24, about eightfold more mesna was excreted by patients given the I.V.-oral than the I.V. regimen. CONCLUSION: These pharmacokinetic data show that the I.V.-oral regimen should be at least as uroprotective as the I.V. mesna regimen. Patients may also benefit from the I.V.-oral regimen because of the higher trough values during hours 0 through 12 and the sustained urinary mesna excretion during hours 12 through 24.

Etoposide: four decades of development of a topoisomerase II inhibitor.

Podophyllin-containing materials have been used as folk medicines for centuries. In the 1950s, scientists began a search to identify a more effective podophyllotoxin derivative. These efforts eventually resulted in the development of a new class of antineoplastic agents which target the DNA unwinding enzyme, topoisomerase II. The history of the development of one of the first identified topoisomerase II inhibitors, etoposide, is reviewed in this paper. Critical developments in etoposide's mechanism of action, pharmacology and administration schedule are summarised. The clinical benefits of the recently marketed etoposide prodrug, etoposide phosphate (Etopophos) are also detailed. The current status of other clinically approved anticancer agents which target topoisomerase II is briefly reviewed.

Paclitaxel/5-fluorouracil/leucovorin in metastatic breast cancer: a Vanderbilt Cancer Center phase II trial.

Fifty-five women with metastatic breast cancer were treated with a regimen consisting of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) 175 mg/m2 administered intravenously over 3 hours on day 1 only plus leucovorin given intravenously over 30 to 60 minutes followed by 5-fluorouracil 350 mg/m2 via intravenous push on days 1 to 3 every 28 days for six cycles. Eight patients were chemotherapy naive. Of 47 previously treated women, 30 had received anthracyclines. Fifty-two patients were evaluable for response. Three (6%) experienced a complete response and 24 (46%) had a partial response, for an overall response rate of 52%. Patients previously exposed to doxorubicin had a response rate similar to those with no prior doxorubicin exposure (50% v 54%, respectively). The median duration of response was 8.6 months and median survival was 17.7 months. Toxicity was modest, with grade 3 or 4 neutropenia observed in only 5.5% (15 of 274) of cycles. Preliminary results indicate that paclitaxel/5-fluorouracillleucovorin is an active, well-tolerated regimen for treating metastatic breast cancer.

Preliminary analysis of a phase II study of paclitaxel, carboplatin, and hyperfractionated radiation therapy for locally advanced inoperable non-small cell lung cancer.

We conducted a prospective phase II study to determine the response rate, toxicity profile, and survival rate among patients with locally advanced unresectable non-small cell lung cancer receiving concurrent weekly paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), carboplatin, and hyperfractionated radiation therapy followed by two cycles of adjuvant paclitaxel and carboplatin. The weekly paclitaxel/carboplatin regimen was designed to optimize the radiosensitizing properties of paclitaxel during the concurrent phase of treatment. Thirty-two patients with unresectable stage IIIA and IIIB non-small cell lung cancer from Vanderbilt Cancer Center Affiliate Network institutions entered the study from June 1996 until February 1997. Weekly intravenous paclitaxel (50 mg/m2 over 1 hour) and weekly carboplatin (area under the concentration-time curve of 2) plus concurrent hyperfractionated chest radiotherapy (1.2 Gy twice daily [69.6 Gy total]) delivered for 6 weeks were followed by two cycles of paclitaxel (200 mg/m2) and carboplatin (area under the concentration-time curve of 6). Among 22 patients evaluable for response, one (4.5%) achieved a complete response and 16 (72.7%) achieved partial response, for an overall response rate of 77%. Among 23 patients evaluable for toxicity, esophagitis was the principal finding: grade 3 or 4 esophagitis occurred in eight patients (35%). Grade 3 and 4 pulmonary toxicities each occurred in 26% of patients. Thus, weekly paclitaxel/carboplatin plus concurrent hyperfractionated radiotherapy is a well-tolerated outpatient regimen with an encouraging response rate that is at least equivalent to more toxic chemoradiation regimens. These findings indicate that further clinical evaluation of weekly paclitaxel/carboplatin/hyperfractionated radiotherapy is warranted in phase III trials.

Paclitaxel, 5-fluorouracil, and folinic acid in metastatic breast cancer: BRE-26, a phase II trial.

5-Fluorouracil plus folinic acid and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) are effective salvage therapies for metastatic breast cancer patients. Paclitaxel and 5-fluorouracil have additive cytotoxicity in MCF-7 cell lines. We performed a phase II trial of paclitaxel 175 mg/m2 over 3 hours on day I followed by folinic acid 300 mg over 1 hour before 5-fluorouracil 350 mg/m2 on days 1 to 3 every 28 days (TFL) in women with metastatic breast cancer. Analysis is reported on 37 patients with a minimum of 6 months follow-up who received a total of 192 cycles of TFL: nine cycles (5%) were associated with grade 3/4 neutropenia requiring hospitalization; seven (4%) cycles in two patients required granulocyte colony-stimulating factor due to neutropenia; no patient required platelet transfusions. Grade 3/4 nonhematologic toxicities were uncommon. Among the 34 patients evaluable for response, there were three complete responses (9%) and 18 partial responses (53%) for an overall response rate of 62%. Of the 19 evaluable patients with prior doxorubicin exposure, 11 (58%) responded compared with nine of 15 (60%) without prior doxorubicin. Plasma paclitaxel concentrations were measured at the completion of paclitaxel infusion and at 24 hours in 19 patients. TFL is an active, well-tolerated regimen in metastatic breast cancer.

Paclitaxel plus carboplatin in the treatment of patients with advanced lung cancer: a Vanderbilt University Cancer Center phase II trial (LUN-46).

In studies conducted by the Eastern Cooperative Oncology Group, treatment with either paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) or carboplatin was associated with an improvement in 1-year survival in patients with stage IV non-small cell lung cancer (NSCLC). Based on these findings, a phase II trial of carboplatin plus paclitaxel was conducted in patients with advanced NSCLC to determine the activity and toxicity of this regimen. Eligibility requirements included stage IIIB or IV histologically confirmed NSCLC, Eastern Cooperative Oncology Group performance status of 0 to 2, no prior chemotherapy, and adequate hematologic, renal, hepatic, and cardiac functions. Paclitaxel was administered intravenously over 24 hours at a dose of 135 mg/m2 (28 patients) or 175 mg/m2 (23 patients), followed by a 1-hour infusion of carboplatin on day 2. Carboplatin was administered at a dose of 300 mg/m2 (16 patients) or, using the Calvert formula, a dose calculated to achieve an area under the concentration-time curve of 6 mg/mL x min (35 patients). Treatment was repeated every 28 days for a total of six cycles. Among the 51 eligible patients, 34 were men and 17 were women; their median age was 60 years and their median Eastern Cooperative Oncology Group performance status was 1. Six patients had stage IIIB and 45 had stage IV disease. Grade 3 or 4 granulocytopenia and thrombocytopenia were observed in 47% and 3% of treatment cycles, respectively. The most common nonhematologic toxicities noted included nausea and emesis, neuropathy, and arthralgia and myalgia. There were no complete responses and 14 partial responses, for an overall response rate of 27% (95% confidence interval, 17% to 41%). Median survival was 38 weeks and the survival rate at 1 year was 32%. Paclitaxel plus carboplatin, as given in this study, was found to be a moderately active regimen in patients with advanced NSCLC. This regimen warrants comparison with existing cisplatin-based regimens in a prospective randomized trial.

Paclitaxel plus carboplatin in advanced non-small-cell lung cancer: a phase II trial.

PURPOSE: Studies conducted by the Eastern Cooperative Oncology Group (ECOG) indicate both paclitaxel and carboplatin are associated with an improvement in 1-year survival in patients with stage IV non-small-cell lung cancer (NSCLC). Based on these findings, a phase II trial of these agents in combination was conducted in patients with advanced NSCLC. PATIENTS AND METHODS: Eligibility included previously untreated stage IIIB or IV NSCLC patients with a good performance status (PS). Paclitaxel (135 or 175 mg/m2) was administered by 24-hour infusion on day 1, followed by a 1-hour infusion of carboplatin on day 2 (300 mg/m2 or dosed to an area under the concentration-time curve [AUC] of 6 mg/mL.min). Treatment was repeated every 28 days for a total of six cycles. Hematopoietic growth factors were not routinely used. RESULTS: Among 51 eligible patients, there were no complete and 14 partial responses, for an overall response rate of 27% (95% confidence interval [CI], 17% to 41%). The median progression-free survival time was 23.8 weeks (range, 12.1 to 73.9) and median survival time, 38 weeks. The survival rate at 1 year was 32%. Grade 3 or 4 granulocytopenia and thrombocytopenia were observed in 47% and 3%, respectively, of the 184 treatment cycles administered. The most common nonhematologic toxicities included nausea and emesis, neuropathy, and arthralgia/myalgia. CONCLUSION: Paclitaxel plus carboplatin is a moderately active regimen in patients with advanced NSCLC and warrants comparison with existing cisplatin-based regimens in a prospective randomized trial. The toxicities of this regimen are well tolerated in patients with a good PS.

The importance of drug scheduling in cancer chemotherapy: etoposide as an example.

Etoposide is a drug whose antineoplastic activity is dependent on the schedule of drug administration. This article reviews the rationale for a prolonged schedule of etoposide administration and the therapeutic results of use of such a schedule in the treatment of cancer. The pharmacology of etoposide is also reviewed, with particular attention paid to the pharmacokinetics of oral etoposide and etoposide plasma concentrations associated with cytotoxicity.

Prevention of cisplatin nephrotoxicity by exogenous atrial natriuretic peptide.

The ability of atrial natriuretic peptide (ANP) to prevent cisplatin-induced nephrotoxicity was compared to the protective effect of 3% NaCl. ANP (1 microgram/kg/min), 3% NaCl or peptide buffer vehicle (50 microliters/min) were infused for 45 min to conscious unrestrained rats immediately after cisplatin administration (5 mg/kg i.v.). Measurements taken 72 h after drug treatment indicated that compared to animals receiving cisplatin only, ANP co-treated rats had lower post-treatment plasma creatinine concentrations (0.70 +/- 0.07 vs 1.3 +/- 0.17 mg/dl; P < 0.05), blood urea nitrogen (BUN) concentrations (44.2 +/- 5.8 vs. 65.5 +/- 2.1 mg/dl; P < 0.05) and higher post-treatment glomerular filtration rates (GFR) (0.71 +/- 0.18 vs. 0.14 +/- 0.03 ml/min; P < 0.05). ANP was as effective as 3% NaCl in preventing cisplatin nephrotoxicity in this model. The effect of ANP co-treatment on the anti-tumor activity of cisplatin was also examined using the Walker 256 carcinosarcoma model. ANP treatment did not result in any observable loss in anti-tumor activity. When ANP was administered 72 h after cisplatin treatment, improvement in GFR was observed for the duration of the infusion, confirming the beneficial effect of ANP on cisplatin-damaged kidneys. ANP may have a role in the treatment and prevention of cisplatin nephrotoxicity especially in clinical situations where treatment with a large fluid volume is contraindicated.