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Successful treatment of advanced-stage Hodgkin's disease (HD) may critically depend on dose intensity. Because mechlorethamine, Oncovin, procarbazine, and prednisone (MOPP), and Adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) are not suitable for major dose escalation, we evaluated the activity and toxicity of combined cyclophosphamide, doxorubicin, vincristine, prednisone, and etoposide (CHOPE) in advanced HD, here used at conventional dose intensity, as a preparatory study prior to using this regimen at higher dose intensity. Ninety-two patients were treated with CHOPE (cyclophosphamide, 750 mg/m2, day 1; doxorubicin, 50 mg/m2, day 1; vincristine, 1.4 mg/m2, days 1 and 8; prednisone, 100 mg/day, days 1-5; and etoposide, 80 mg/m2, days 1, 2, and 3) every 21 days. All had advanced HD with no prior chemotherapy with 46% stage IV, 63% with B symptoms, and 57% with bulky disease (> 5 cm). Radiation and growth factor support were not permitted. Full-dose vincristine (not capped at maximum 2 mg/dose) was used in the first 33 patients. An initial cohort of 41 patients was treated with four cycles of CHOPE to evaluate safety and efficacy followed by four cycles of ABVD. A second cohort of 51 patients was treated with 6-8 cycles of CHOPE alone. Toxicity was generally acceptable and primarily hematologic, with neutrophils < 500 in 63% of cohort I and 90% of cohort II, and platelets < 25,000 in 7% of cohort I and 8% of cohort II. The long-term neurotoxicity of full-dose, high-intensity vincristine was acceptable and largely reversible. In cohort I, 92% of patients achieved a complete response (CR) or partial response (PR) with four cycles of CHOPE and 85% were in CR after four additional cycles of ABVD. In cohort II, 77% achieved a CR with 6-8 cycles of CHOPE alone. FFS was 76% in cohort I and 59% in cohort II, with a median follow-up of 8.2 and 5.7 years, respectively. CHOPE, at conventional dose intensity as used here, is an effective first-line regimen for the treatment of advanced-stage HD and may warrant evaluation using higher doses of cyclophosphamide and etoposide with granulocyte colony stimulating factor (G-CSF) support.

PURPOSE To construct a single scale for comparing the dose-intensity of all chemotherapy regimens in breast cancer. MATERIALS AND METHODS First-line single-agent trials in metastatic disease were reviewed. The unit dose-intensity (UDI) that was required to produce a 30% complete response plus partial response (CR + PR) rate was determined for each drug. Randomized trials were then analyzed that prospectively tested dose-intensity. The dose-intensities of the drugs in each arm were expressed as fractions of their UDIs and added together. This yielded each arm's summation dose-intensity (SDI), which was then correlated with treatment outcomes. RESULTS In the single-agent trials, dose-response relationships were linear when the studies covered a range of dose-intensities. In the randomized trials that tested dose-intensity in metastatic disease, response rates and median survival correlated linearly with the SDIs of the treatment arms. An increment of one SDI unit increased CR + PR rate by approximately 30%, CR rate by 10%, and median survival by 3.75 months. Metastatic disease trials were negative if the difference between the arms was less than 0.54 SDI units. Adjuvant trials that tested a dose-intensity difference of less than 0.65 SDI units were also negative. CONCLUSION A single-agent dose-response database can be derived from historic literature that enables comparison of the dose-intensity of all combination regimens on one scale. The dose-intensity increase required to improve outcome can then be identified in earlier trials that tested that variable. SDI methodology should be tested prospectively in contemporary patients, and may be useful in guiding dosage increases beyond the conventional range.

Background: Both total dose and dose intensity of adjuvant chemotherapy are postulated to be important variables in the outcome for patients with operable breast cancer. The Cancer and Leukemia Group B study 8541 examined the effects of adjuvant treatment using conventional-range dose and dose intensity in female patients with stage II (axillary lymph node-positive) breast cancer. Methods: Within 6 weeks of surgery (radical mastectomy, modified radical mastectomy, or lumpectomy), 1550 patients with unilateral breast cancer were randomly assigned to one of three treatment arms: high-, moderate-, or low-dose intensity. The patients received cyclophosphamide, doxorubicin, and 5fluorouracil on day 1 of each chemotherapy cycle, with 5fluorouracil administration repeated on day 8. The highdose arm had twice the dose intensity and twice the drug dose as the low-dose arm. The moderate-dose arm had two thirds the dose intensity as the high-dose arm but the same total drug dose. Disease-free survival and overall survival were primary end points of the study. Results: At a median follow-up of 9 years, disease-free survival and overall survival for patients on the moderate- and high-dose arms are superior to the corresponding survival measures for patients on the low-dose arm (two-sided P

PURPOSE With a median observation time of 50 months from transplant, 13 (22%) of 62 women with metastatic breast cancer treated with high-dose chemotherapy at the Dana-Farber Cancer Institute (DFCI)/Beth Israel Hospital (BIH) remain progression-free. This study determined factors prognostic for prolonged progression-free survival (PFS). METHODS From June 1988 to January 1992, women who responded to standard chemotherapy received high-dose cyclophosphamide, thiotepa, and carboplatin with autotransplantation. Data encompassing initial breast cancer diagnosis, metastatic presentation, and response to induction treatment were examined for correlations with improved PFS. RESULTS The 5-year PFS rate for the entire group is estimated to be 21% (95% confidence interval [CI], 10% to 32%). For those patients who attained a complete response (CR) to induction therapy, the 5-year PFS rate is estimated to be 31% (95% CI, 0% to 63%). In univariate analyses, a single metastatic site, CR to induction therapy, prolonged interval from primary diagnosis to first metastases, estrogen receptor (ER)-negative tumors, and older age (> or = 40 years) were associated with prolonged PFS. In multivariate analyses, single metastatic site (P = .002) and attainment of a CR to induction chemotherapy (P = .04) were the most significant predictors for PFS, with a strong trend observed for an interval from primary diagnosis to onset of metastatic disease of 24+ months (P = .066). CONCLUSION We and others have shown that 10% to 25% of women with metastatic breast cancer are progression-free after high-dose chemotherapy with autotransplantation. Those with chemosensitive disease, minimal tumor bulk, and a prolonged disease-free interval appear to benefit most. Emphasis should continue to focus on the development of more effective cytotoxic regimens and biologic approaches to increase the percentage of patients who may benefit from this approach.

Relapse after high-dose alkylating agent therapy continues to be an important clinical issue. To begin to understand the characteristics of cells surviving alkylating agent exposure human MCF-7 breast carcinoma cells were exposed to a range of concentrations of melphalan or cis -diamminedichloroplatinum(II) and cell survival determined by colony formation over a time course of 4 weeks. When antitumor alkylating agent exposure killed 3–4 logs of cells as determined by surviving fraction after 1 week of colony formation a progressive increase in surviving fraction was evident over the 4-week course of the experiment. Many attached single cells with abnormal morphology were evident in these dishes; however, the colonies which arose over the 4-week observation time were made up of cells morphologically indistinguishable from the control cells. Cell cycle patterns in the cultures exposed to high concentrations of the antitumor alkylating agents indicated a block in G 2 M but by 4 weeks post-drug exposure most had returned to a normal exponential growth pattern. When MCF-7 cells or human SW2 small cell lung cancer cells were exposed to a concentration of melphalan or cis -diamminedichloroplatinum(II) that killed 1–2 logs of cells followed by exposure to a concentration range of the same drug for 24 h or 7 days later resistance to the second drug exposure was evident in both cell lines. Using [ 14 C]melphalan the uptake of the drug into MCF-7 cells pre-treated with melphalan or not pretreated was compared. Decreased drug uptake did not appear to be a factor in resistance to melphalan observed upon re-exposure to the drug. The potential clinical implications of these findings is discussed.

Adjuvant chemotherapy is widely used for breast cancer and is known to extend survival. Some clinicians seek a greater survival benefit by increasing the intensity of the dose, whereas others lower it to diminish toxicity.The Cancer and Leukemia Group B (CALGB) conducted a randomized trial of different levels of doses and dose intensity (dose per unit of time) of adjuvant chemotherapy in 1572 women with node-positive, stage II breast cancer who were assigned to three treatment groups. One group received 400 mg of cyclophosphamide per square meter of body-surface area and 40 mg of doxorubicin per square meter once every 28 days and 400 mg of fluorouracil per square meter twice every 28 days, for six cycles. Another group received 50 percent higher doses of the three drugs (600 mg, 60 mg, and 600 mg, respectively) but for only four cycles, so that the total dose was identical in these two groups but the dose intensity was higher in the first. The third group of women received half the total dose used in the other two groups and at half the dose intensity used in the second group.After a median of 3.4 years of follow-up, the women treated with a high or moderate dose intensity had significantly longer disease-free survival (P0.001) and overall survival (P = 0.004) than those treated with a low dose intensity, in three-way log-rank comparisons. However, the difference in survival between the two groups treated with a moderate or high dose intensity was not significant. These results are consistent with either a dose-response effect or a threshold level of the dose or dose intensity.The doses of chemotherapy used to treat breast cancer, especially early breast cancer, should not be reduced if the maximal benefit is to be achieved.

BACKGROUND Cisplatin, 5-fluorouracil, and leucovorin (PFL) have demonstrated synergistic activity in preclinical models. Continuous infusion of these agents maximizes the potential for synergistic interaction and forms the basis of the PFL regimen. METHODS Sixty-one patients with advanced (Stages IIIB and IV) non-small cell lung cancer were entered into the study. Thirty-one were treated with cisplatin 25 mg/m2/day on days 1-5, 5-fluorouracil 800 mg/m2/day on days 2-6, and calcium leucovorin 500 mg/m2/day on days 1-6. Because of severe mucositis, the final 30 patients were treated with the same dosage of cisplatin but with the deletion on day 6 of leucovorin and 5-fluorouracil. Cycles were repeated every 28 days. Response was assessed after two cycles. Responding patients received an additional two cycles. Patients with Stage IIIB disease received radiation therapy to the mediastinum and sites of involved disease. RESULTS PFL had an overall response rate of 41%. Median survival was 8.1 months, and median time to treatment failure was 4.2 months. Importantly, 68% (17 of 25) of responses were maximal after just two cycles of chemotherapy. Notable toxicities included mucositis (43% > or = Grade 3) and myelosuppression. Response, time to failure, or survival did not differ between the two schedules. Mucositis was less severe with 4-day PFL. CONCLUSIONS PFL as given in this manner is an active regimen for the treatment of patients with advanced non-small cell lung cancer. The rapidity of response makes it a regimen for incorporation into protocols for Stage IIIA disease. A neoadjuvant study using PFL is underway.

The multimodality approach to locally advanced Stage III non-small cell lung cancer is continuing to evolve. In this trial, 54 patients with surgically staged IIIA disease were treated with neoadjuvant chemotherapy, surgical resection, and chest radiotherapy. Response to four cycles of CAP chemotherapy (cyclophosphamide, doxorubicin, cisplatin) was 39% (8% complete responses). One septic death occurred. Thoracotomy was performed on 31 patients, of whom 29 (56%) were resected and 24 (44%) were completely resected. Complete resections were more frequently observed in chemotherapy responders. Extranodal mediastinal extension in nonresponding patients was the most frequent reason not to attempt thoracotomy. The overall median times to progression and survival were 11.6 (.7-66.5) and 17.9 (2.8-71.4) months. Long-term disease-free survival was observed in 11 patients (20%) with a median follow-up of 46.5 (24-71) months. All these patients underwent complete resection and constitute 46% of the patients undergoing complete resection. Median times to progression and survival were 33.4 (5.0-66.5) and 33.5 (10-71.4) months for completely resected patients. Although the ability to perform surgery identified a population that has favorable locoregional control and disease-free survival, distant relapse continues to represent the major obstacle to enhanced survival in resected patients. Unresected patients, however, are likely to relapse in both local and distant sites. Response to chemotherapy may not only enhance systemic control, but may also increase the probability of complete resection. Randomized trials should be conducted to evaluate the role of individual modalities (surgery, chemotherapy, or radiotherapy) while applying the remaining modalities maximally. The temptation to compare different treatment approaches should be resisted.

Using a computer-controlled polarographic oxygen electrode system, the oxygen tension profiles of two rat tumors, the 13762 mammary carcinoma and the 9L gliosarcoma, and one murine tumor, the FSall fibrosarcoma, were determined under eight different conditions. The oxygen profiles were characterized by four parameters related to tumor oxygenation and by three parameters related to tumor hypoxia. In the rat 13762 mammary carcinoma tumor median pO2 and the percent of pO2 were correlated with tumor volume under three different conditions. With these tumors the decrease in percent of pO2 readings in the tumor

In a continuing investigation of determinants of their 200-fold methotrexate resistance and their collateral sensitivity to γ - tert -butyl methotrexate, the ability of CEM/MTX cells to transport the two drugs was analyzed and compared with that of CEM cells. The K m and V max values for the influx of methotrexate into CEM cells did not differ significantly from those of CEM/MTX cells, and this was the case for γ - tert -butyl methotrexate as well. Surface binding and influx rates were proportional to cell surface area, but differences in efflux rates and methotrexate uptake were too large to be explained on this basis. Neither methotrexate nor trimetrexate competed with γ - tert -butyl methotrexate influx in CEM cells. However, both drugs perturbed the γ - tert -butyl methotrexate steady state in CEM cells, resulting in slightly less uptake than with γ - tert -butyl methotrexate alone. However, the major difference between the two cell types was in the methotrexate uptake plateau, which was much greater in the case of the parental cell line. A related observation was the more rapid efflux of methotrexate from CEM/MTX cells than from CEM cells. The poor uptake, the associated meager capacity to polyglutamylate methotrexate and the enhanced methotrexate efflux appear to be responsible for its decreased activity against CEM/MTX cells. Half-lives for γ - tert -butyl methotrexate efflux were the same in both cell lines, allowing the drug to accumulate to cytotoxic levels despite its inability to form polyglutamates.

Background. Cisplatin and etoposide combination chemotherapy is the most commonly used regimen for advanced non-small cell lung cancer (NSCLC). 5-Fluorouracil (5-FU) is an agent with little intrinsic activity against NSCLC. However, there is increasing evidence that 5-FU is synergistic with cisplatin and vice versa. In an effort to improve on the traditional chemotherapeutic approach to NSCLC, a treatment regimen consisting of cisplatin, 5-FU, and etoposide (PFE) was developed. Methods. Thirty-five patients with advanced NSCLC were treated with the PFE regimen (cisplatin 25/mg/m2/d and 5-FU 1000 mg/m2/d by continuous infusion and etoposide 60 mg/m2/d, each for 4 days). The cycles were repeated every 28 days. Results. The patients received a mean of 2.8 cycles of PFE. Ten patients had a partial response to chemotherapy for an overall response rate of 28.6%. The median survival was 7.0 months. Toxicities included myocardial infarction (2 of 35), congestive heart failure (2 of 35), fatal pulmonary embolus (1 of 35), and a cerebrovascular accident (1 of 35). The incidence of Grade 4 neutropenia (5.7%) and thrombocytopenia (8.5%) was acceptable. Conclusions. The response rate, duration of response, and survival in this group of 35 patients treated with PFE was similar to that reported for cisplatin and etoposide. The increased cardiovascular toxicity may be the result of the infused 5-FU.

High dose chemotherapy with autologous bone marrow support (ABMT) can achieve prolonged relapse-free survival in relapsed lymphomas, leukemias, and certain solid tumors. The principal morbidity and mortality relate to the infectious complications that occur during the 3-4 week aplasia until the marrow autograft recovers. Progenitor cells can be mobilized into the peripheral blood compartment by hematopoietic growth factors, used alone or after chemotherapy. We describe four trials using cytokine-mobilized peripheral blood progenitor cells (PBPC). In the first trial, PBPC collected after GM-CSF administration were used to augment marrow. Reconstitution of trilineage marrow function occurred promptly, resulting in short hospital stays and fewer platelet transfusions. In a second study, GM-CSF/chemotherapy-mobilized PBPC were used as the sole hematopoietic support during high dose chemotherapy. Granulocyte and platelet reconstitution was rapid. Time to hematopoietic recovery, transfusion requirements, and duration of hospital stay were all significantly improved for the patients receiving PBPC compared with similar patients receiving marrow alone. While most patients experienced prompt hematopoietic recovery they showed sluggish platelet engraftment. The next two trials built on the observation that a few PBPC alone could support both granulocyte and platelet recovery and were designed to test the feasibility of sequential high-dose therapies. In one trial, PBPC given with and without marrow made it possible to deliver two sequential cycles of high-dose therapy. The second trial utilized PBPC plus cytokines to deliver four cycles of dose-intensive chemotherapy at doses that could not be given with cytokine support alone.(ABSTRACT TRUNCATED AT 250 WORDS)

The overall median survival of women with advanced or high-risk primary breast cancer has not changed with conventional chemotherapy. Regimens employing high-dose chemotherapy with autologous stem cell support (ABMT) have been developed with the hope of optimizing tumor response and increasing survival. Early phase I studies in women with advanced refractory disease achieved high response rates of short duration. Second generation studies combined an induction phase followed by one high-dose intensification at time of maximum tumor response. The Dana-Farber Cancer Institute/Beth Israel Hospitals have developed the high-dose intensification regimen of cyclophosphamide, thiotepa, and carboplatin (CTCb) for use in women with metastatic and high-risk stage IIIB/inflammatory breast cancer. To date, approximately 19% of women with metastatic disease remain progression free using this approach, with median length of follow-up approaching 40 months. Although the median duration of follow-up for the stage IIIB women is much shorter (approximately 12 months), greater than 90% of these women are thus far disease free. With the advent of hematologic support, such as blood stem cells and colony-stimulating factors, the morbidity, mortality, and costs associated with this treatment have been substantially reduced, allowing for two or more cycles of high-dose intensification to be employed, to exploit the potential of dose-intensity to optimize response.

Background Cisplatin and 5-fluorouracil have noted synergy in preclinical systems. The authors combined methotrexate with infusional cisplatin and 5-fluorouracil in an attempt to produce a regimen with improved activity in advanced NSCLC: Methods Twenty-six ambulatory patients with previously untreated non-small cell lung cancer were treated with continuous-infusion cisplatin (25 mg/m2/day for 5 days), 5-fluorouracil (800 mg/m2/day for 5 days), and intermediate-dose methotrexate (200 mg/m2 on days 15, 22), followed by leucovorin rescue (PFM regimen). Results Patients received a median of four cycles of therapy. Two patients had a complete response, and 10 had a partial response (overall response rate, 46.2% or 12 of 26). The median time to treatment failure was 22.5 weeks; the median survival was 55 weeks from the start of chemotherapy. There were no toxic deaths attributed to chemotherapy. Thrombocytopenia was the only Grade 4 toxicity (27%). Grade 1/4 and 2/4 peripheral neuropathy occurred in 17 of 26 patients (66%) and was associated with a cumulative cisplatin dose of more than 300 mg/m2. Conclusions PFM (using continuous-infusion cisplatin) produced a high response rate but resulted in an high incidence of low-grade peripheral neuropathy.

Patients with testicular cancer treated with cisplatin can undergo feminization that is understood poorly. Rat model studies recently showed that cisplatin can feminize in part the profile of hepatic steroid-metabolizing enzymes and circulating hormone levels. This study was undertaken to determine whether cisplatin similarly might contribute to the perturbations in gonadotropin or steroid hormone levels that can occur in patients undergoing cisplatin-based treatment for testicular cancer. Analysis of serum free testosterone, total testosterone, and androstenedione levels revealed that these hormones were not altered significantly in patients during a 38-week period of cisplatin-based treatment and follow-up. Estradiol levels were elevated before chemotherapy and were reduced to normal levels during treatment. This reduction was attributed to the cytotoxic effect of chemotherapy on the tumors and the resultant reduction in serum chorionic gonadotropin levels. Serum dihydrotestosterone (DHT) levels were normal before chemotherapy but progressively became elevated during treatment with cisplatin in five of ten patients examined. The rise in DHT may relate to the previously described increase in hepatic androgen 5 alpha-reductase activity in cisplatin-treated rats. Levels of the gonadotropins, luteinizing hormone, and follicle-stimulating hormone (FSH) were normal before cisplatin-based treatment was administered; however, FSH was elevated selectively during chemotherapy. This selective induction of FSH may reflect an effect of cisplatin on the hypothalamic secretion of gonadotropin-releasing hormone. Taken together, these findings suggest that cisplatin contributes to the perturbation of steroid and peptide hormone levels in patients with testicular cancer and perhaps in others undergoing cisplatin-based chemotherapy.

The National Cancer Institute funds and coordinates a large international system of clinical trials, involving many large and small institutions and thousands of patients, which is organized into a dozen cooperative groups. Compliance with the study requirements and data accuracy are monitored at several levels within these collaborative groups. In addition, for approximately 9 years an on‐site data audit process has been conducted by each group. We report the organization and audit methods of one of these groups, the CALGB. In 3 cycles of auditing each CALGB institution, involving over 2300 patients, there have been only 2 instances of scientific improprieties, a rate of only 0.4% in 459 institutional audits. A more worthy result of this on‐site data auditing has been the improvement in compliance with protocol and administrative requirements. Although a system of on‐site reviews of patient records expends both scarce research funds and investigator time, the CALGB has demonstrated the value of such audi...

High-dose chemotherapy with autologous bone marrow support (ABMS) achieves prolonged relapse-free survival in relapsed lymphomas and leukemias and has provided durable complete responses in certain solid tumors. The principal morbidity and mortality result from the infectious and bleeding complications during the 3–4 week aplasia until the bone marrow autograft can recover. Hematopoietic growth factors, alone or used after chemotherapy, increase the number of circulating progenitor cells in the peripheral blood compartment. In one trial, 12 patients with solid tumors were treated with high-dose chemotherapy and supported with both bone marrow and peripheral blood progenitor cells (PBPC) collected after GM-CSF administration. Reconstitution of bone marrow function occurred quickly (ANC >500/µl by day 17; platelet-transfusion independence by day 16), resulting in short hospital stays (median, 28 days). In a second study, 12 patients with metastatic breast cancer responding to induction chemotherapy (doxorubicin, 5-fluorouracil, and methotrexate) were given GM-CSF during induction to collect PBPCs during leukocyte recovery. These PBPCs were used as the sole hematopoietic support during high-dose chemotherapy with cyclophosphamide, thiotepa, and carboplatin. Granulocyte and platelet reconstitution were extremely rapid (median, 14 and 12 days, respectively). When compared with 29 patients undergoing the same intensification therapy using ABMT as sole support, time to hematopoietic recovery, transfusion requirements, and duration of hospital stay were all significantly improved for the patients receiving PBPC. PBPC with or without marrow may enhance the safety, tolerance, and cost of high-dose therapy. Moreover, PBPC may render multiple course combination, high-dose therapy feasible.

In this phase I study, 16 adult cancer patients were treated with concurrent 4-day continuous infusions of ifosfamide at 12 g/m2 and escalating doses of carboplatin (400-1600 mg/m2) to determine the major non-haematological dose-limiting toxicity of the combination. Mesna was given by continuous infusion over 5 days for uroprotection (total dose per course = 15 g/m2). Autologous bone marrow support, which was mandated for subsequent dose levels once granulocytes remained below 500/microliters for more than 14 days in at least 2 patients entered at a given dose level, was used at dose levels above 400 mg/m2 carboplatin. Renal toxicity became dose-limiting at the maximum tolerated dose level of 1600 mg/m2 carboplatin. Temporary creatinine elevations above 2 mg/dl (median peak 2.6 mg/dl) were observed in 3 and irreversible renal toxicity occurred in 1 (peak creatinine 6.9 mg/dl, chronic creatinine 5-6 mg/dl) of the 5 patients entered at this dose level. Severe confusion and lethargy associated with rising creatinine developed in 2 patients. Two complete and four partial responses were documented in 14 heavily pretreated evaluable patients. The complete responses continue at 14+ and 20+ months in a patient with germ cell carcinoma and Ewing's sarcoma, respectively. Carboplatin appears to contribute to the renal toxicity of ifosfamide. Nevertheless, the combination of carboplatin and ifosfamide at 80% and 75% of the single-agent maximal tolerated doses respectively produced acceptable non-haematological toxicity. Further studies in the treatment of sarcoma, germ cell, ovarian and lung carcinomas with this combination are warranted.

In an effort of improve the therapeutic efficacy and selectivity of cyclophosphamide (CTX),cis-diamminedichloroplatinum(II) (CDDP), and carboplatin (Carbo), these antitumor alkylating agents were combined with the 2-nitroimidazole drug etanidazole (ETA). As revealed by tumor-cell survival assay in the FSaIIC murine fibrosarcoma, the addition of ETA (1 g/kg, i.p.) just prior to the i.p. injection of various doses of the alkylating agents resulted in increases in the tumor-cell kill produced by each drug (CTX, 10-fold; CDDP, 20-fold; and Carbo, 5-to 15-fold), whereas toxicity to bone marrow granulocytemacrophage colony-forming units (CFU-GM) increased only about 0- to 3-fold. When CTX was combined with either CDDP or Carbo, striking increases in tumor-cell killing were observed (20- to 100-fold across the CDDP dose range and 5- to 20-fold across the dose range of Carbo), which were supra-additive for CDDP and additive for Carbo as revealed by isobologram analysis. The addition of ETA to these alkylating-agent combinations produced a further approx. 20-fold increase in tumor-cell kill for both CTX/CDDP and CTX/Carbo. This effect was greatest at the lowest dose of the platinum drug tested and was supra-additive in the case of CDDP and additive for Carbo. Following treatment with ETA/CTX/CDDP, bone marrow CFU-GM toxicity increased only about 5-fold over that of CTX/CDDP alone, but the injection of ETA/CTX/Carbo resulted in a 10- to 20-fold increase in bone marrow toxicity as compared with that obtained using CTX/Carbo alone. Tumor growth-delay studies revealed significant increases in the antitumor effect of the alkylating agents when these were given in combination with ETA. Both the ETA/CTX/CDDP and the ETA/CTX/Carbo combinations produced tumor growth delays of 23 days, which represented approx. 1.6-fold increases over those obtained using the alkylating-agent combinations alone. These results suggest that ETA could significantly improve the therapeutic efficacy of these alkylating agents, whether they therapeutic efficacy of these alkylating agents, whether they are given individually or in combination.

EMT-6 murine mammary tumors were made resistant to cis-diamminedichloroplatinum (II) (CDDP), carboplatin, cyclophosphamide (CTX), or thiotepa in vivo by treatment of tumor-bearing animals with the drug during a 6-month period. In spite of high levels of in vivo resistance, no significant resistance was observed when the cells from these tumors were exposed to the drugs in vitro. The pharmacokinetics of CDDP and CTX were altered in animals bearing the respective resistant tumors. The resistance of all tumor lines except for the EMT-6/thiotepa decreased during 3 to 6 months in vivo passage in the absence of drugs. These results indicate that very high levels of resistance to anticancer drugs can develop through mechanisms that are expressed only in vivo.

The mechanism of tumour necrosis factor (TNF) cytotoxicity remains unknown. The in vivo antitumour effects of TNF may be related to direct cytotoxicity, immunomodulatory effects or endothelial effects on tumour vasculature. Phase I and early Phase II clinical trials of human recombinant TNF are under way in Japan, the USA, the UK and Germany. The maximum Phase II dose for TNF has not been established. The clinical toxicity of TNF is generally similar to that of other biological agents. Systemic toxicity, including fever, chills, anorexia and nausea, has been seen in most patients treated with TNF and has not been clearly related to dose. Other toxicities have included liver function abnormalities, hypotension, transient neurological changes and haematological abnormalities. Few clinical responses have been reported but organized Phase II testing remains to be completed. Combination trials with interferons have recently been initiated. Phase II efficacy studies of TNF as a single agent and in combination are needed for an assessment of the value of this agent in cancer therapy.

A formal National Cancer Institute Clinical Trials Cooperative Group Program was conceived in 1955 when Dr. Sidney Farber, Mary Lasker, and others approached Congress with a proposal to increase support for studies of chemotherapy of cancer. In response, Congress awarded US $5 million to the National Cancer Institute to establish the Chemotherapy National Service Center. The founders of the Cancer and Leukemia Group B, James Holland and Emil (Tom) Frei, III, envisioned that successful chemotherapy for leukemia and other hematologic malignancies could be expeditiously realized through carefully designed clinical trials executed uniformly as a cooperative effort among several institutions. In 1956, the group was designated the Acute Leukemia Group B by the Chemotherapy National Service Center Clinical Studies Panel, and Frei was elected chairman. In the ensuing 50 years, the Cancer and Leukemia Group B has expanded to national and even international membership, and its research programs have expanded to include all of the common adult solid tumors and hematologic malignancies in a multidisciplinary effort to improve the outcomes for patients with cancer and to better understand the biology of malignant disease.

Prevention of cigarette smoking and early lung cancer detection remain important in our approach to the control of non-small cell lung cancer (NSCLC). In recent years, chemotherapy has emerged as a viable option in the treatment of NSCLC. The most impressive and widely confirmed evidence for this is the fact that chemotherapy can eradicate NSCLC micrometastases. Indeed, in some studies employing neoadjuvant chemotherapy followed by local surgery, pathology-confirmed complete remission rates as high as 20% have been reported. New agents showing preliminary activity in NSCLC include paclitaxel, vinorelbine, gemcitabine, and irinotecan (CPT-11). Certainly, however, there remains a need for novel, effective single-agent and combination chemotherapies. The seed/soil tumor concept, in which the seed consists of the tumor cells per se and the soil is the stroma containing the seeds, has proven helpful in devising new treatment strategies. Such strategies may include the use of antisoil agents, including antiangiogenesis, anti-invasion, and antimetastasis agents, both separately and particularly in conjunction with established antitumor agents. New therapeutic targets and methods of antitumor agent development based on modern molecular biology and pharmacology will provide a greater opportunity to improve the treatment of NSCLC.

Purpose: This study was designed to determine whether increasing the dose of doxorubicin in or adding paclitaxel to a standard adjuvant chemotherapy regimen for breast cancer patients would prolong time to recurrence and survival. Patients and Methods: After surgical treatment, 3,121 women with operable breast cancer and involved lymph nodes were randomly assigned to receive a combination of cyclophosphamide (C), 600 mg/m2, with one of three doses of doxorubicin (A), 60, 75, or 90 mg/m2, for four cycles followed by either no further therapy or four cycles of paclitaxel at 175 mg/m2. Tamoxifen was given to 94% of patients with hormone receptor–positive tumors. Results: There was no evidence of a doxorubicin dose effect. At 5 years, disease-free survival was 69%, 66%, and 67% for patients randomly assigned to 60, 75, and 90 mg/m2, respectively. The hazard reductions from adding paclitaxel to CA were 17% for recurrence (adjusted Wald χ2 P = .0023; unadjusted Wilcoxon P = .0011) and 18% for death (adjusted P = .0064; unadjusted P = .0098). At 5 years, the disease-free survival (± SE) was 65% (± 1) and 70% (± 1), and overall survival was 77% (± 1) and 80% (± 1) after CA alone or CA plus paclitaxel, respectively. The effects of adding paclitaxel were not significantly different in subsets defined by the protocol, but in an unplanned subset analysis, the hazard ratio of CA plus paclitaxel versus CA alone was 0.72 (95% confidence interval, 0.59 to 0.86) for those with estrogen receptor–negative tumors and only 0.91 (95% confidence interval, 0.78 to 1.07) for patients with estrogen receptor–positive tumors, almost all of whom received adjuvant tamoxifen. The additional toxicity from adding four cycles of paclitaxel was generally modest. Conclusion: The addition of four cycles of paclitaxel after the completion of a standard course of CA improves the disease-free and overall survival of patients with early breast cancer.

Treatment for extensive-stage small cell lung cancer (ES SCLC) or extrapulmonary small cell carcinoma (EPSC) is typically palliative. We set out to determine progression-free survival (PFS) and overall long-term survival of ES SCLC and EPSC patients, physiologically agedor = 60 years, responding to first-line chemotherapy followed by high-dose combination alkylating agents with hematologic stem cell support. Patients in first-line chemotherapy response underwent stem cell collection (marrow, peripheral blood progenitor cells, or both) followed by high-dose therapy with 1 of 2 regimens: CBP (cyclophosphamide, cisplatin, and carmustine) or ICE (ifosfamide, carboplatin, and etoposide) with or without etanidazole. Involved-field radiotherapy was given to selected patients with oligometastatic disease distributed in sites allowing for reasonable radiation ports, and prophylactic cranial radiotherapy was given upon recovery to patients in complete response (CR) or near-CR. A total of 36 patients were treated. Of 29 patients with ES SCLC, 6 (21%) had achieved CR, 18 near-CR, and 5 partial response prior to high-dose therapy. Of 7 patients with EPSC, 3 (43%) had achieved CR, 3 had achieved near-CR, and 1 had progression of disease prior to high-dose therapy. Thirteen ES SCLC patients received high-dose CBP. Of the remaining 23 patients with SCLC or EPSC, 17 were treated with ICE and 6 with ICE plus etanidazole, a hypoxic cell sensitizer. Treatment-related mortality was 11% (4 of 36 patients). For all patients, the median event-free survival (EFS) was 5 months. The 2- and 5-year survivals after intensification were 12% (95% confidence interval [CI], 5%-31%) and 9% (95% CI, 3%-27%), respectively. Of the 30 patients in or near CR prior to high-dose therapy, 5 remain continuously progression-free (2 ES SCLC, 3 EPSC) for a median of 55 months (range, 1-96 months) after high-dose therapy. By multivariate analysis, factors associated with more favorable EFS were the use of a more aggressive induction regimen (ICE), and the EPSC histology. These factors were also associated with more favorable overall survival. Other factors associated with more favorable overall survival were the use of short induction therapy (or = 4 cycles) and younger age (50 years). Except for high-dose ICE with etanidazole, the use of high-dose systemic therapy in ES SCLC and EPSC was associated with low treatment-related morbidity and mortality over the past 5 years. Late complications were infrequent, and most patients returned to full-time work and activity, barring disease recurrence. Nonetheless, few patients with ES SCLC have progression-free long-term survival. We conclude that high-dose therapy is not indicated as an approach for ES SCLC, except as part of an investigative trial. Conversely, 3 of the 7 patients with EPSC remain relapse-free (range, 1-96 months), warranting further phase II evaluation of this approach in this population.

Although initially responsive to chemotherapy, patients with small-cell lung cancer (SCLC) almost invariably suffer relapse. Recurrent SCLC responds poorly to treatment. Previous trials using high-dose chemotherapy with bone marrow support have commonly used single agents or combined alkylating agents without chest radiotherapy. Among patients with limited disease receiving dose-intensive chemotherapy, locoregional relapse remained the predominant site of first failure. Recent phase II trials using intensive locoregional therapy (aggressive concurrent chemoradiotherapy) have resulted in promising survival. Our trial used combined alkylating agents with autologous marrow support and chest radiotherapy in patients with limited disease in response to conventional-dose induction chemotherapy. Of 19 patients treated, the actuarial survival was 56% with a median follow-up of 18 months following high-dose therapy. Patients who achieved complete or near-complete response prior to high-dose therapy enjoyed the best prognosis. Continued evaluation of intensive systemic and local therapy for SCLC is indicated.

Two cycles of high-dose chemotherapy with stem cell support (HDC) may increase the total dose delivered and dose intensity. A brief induction phase and different non-cross-resistant agents for each HDC cycle were used to avoid drug resistance. Twenty-six women with metastatic BC had induction and stem cell mobilization with two cycles of doxorubicin/G-CSF given every 14 days. Patients with stable disease or better after induction received HD CTCb followed by HD melphalan and dose-escalated paclitaxel. At 475 mg/m(2) of paclitaxel by 24-h infusion, dose-limiting transient peripheral sensory neuropathy was encountered. No toxic deaths occurred. Complete and near complete response after completion of therapy was achieved in 22 (85%) of 26 patients. The median EFS was 38 months. The median OS has not yet been reached. At a median follow-up of 33 (25-43) months, actuarial EFS and OS were 54% (95% confidence interval (CI), 39-69%) and 69% (95% CI, 56-79%), respectively. This double transplant approach lasts only 14 weeks and is feasible, safe, and tolerable. Whilst selection biases may in part contribute to favorable EFS and OS, a randomized comparison of standard therapy vs double transplant in both metastatic and locally advanced breast cancer is warranted.

Introduction: A preliminary analysis of our double high-dose chemotherapy with stem cell rescue (HD-SCR) clinical trial for breast cancer, and preclinical cross-resistant studies, suggested that melphalan (M) adversely affected response to subsequent chemotherapy, i.e., that the sequence of alkylating agents (AAs) might affect response. We, therefore, constructed and examined preclinical models to determine whether prior exposure to M, in fact, adversely affected response to other therapy. Purpose: The purpose of the study was to determine whether the sequence of AAs, specifically the prior use of M, adversely affected response to subsequent treatment. Methods: The methods employed were the following: (1) Human tumor cell lines rendered resistant by in vitro sequential exposure to five different AAs were developed. The resistant cell lines were examined for cross-resistance to alkylating and other agents. (2) In vivo studies in the p388 mouse leukemia for resistance and cross-resistance among the AAs. (3) In vivo studies of the effect of sequence of AAs on response in mice bearing EMT6 breast cancer. (4) The double transplant model was developed in the mouse and the sequence of high-dose AAs was studied. (5) Biochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) studies of the various resistant tumor cell lines. Results: (1) The in vitro human tumor cells resistant to M were cross-resistant in 57% of tests to other AAs. In contrast, resistance for other AAs crossed to other agents in only 10 to 20% of tests. (2) The in vivo studies of p388 indicated that resistance to M commonly crossed to other AAs and many non-AAs. (3) The results for the mouse breast cancer (EMT6) studies of the sequence of AAs again indicated that M employed first markedly reduced responsiveness to subsequent treatment, particularly with AAs. (4) The double transplant model: again, M first markedly reduced response to other agents. (5) The in vitro resistant human tumor cell lines, particularly the breast cancer cell line MCF7, were found to contain high concentrations of glutathione S1 transferase gamma, which is consistent with that mechanism being responsible for resistance. Conclusion: The sequence of alkylating agent treatment may substantially influence response. Melphalan, particularly, produces resistance that commonly crosses to the other AAs. Mechanistic studies indicate significant changes in glutathione S1 transferase, a known mechanism for broadly based resistance to AAs.

PURPOSE: To determine progression-free survival (PFS) and overall long-term survival for limited-stage small-cell lung cancer (SCLC) patients aged 60 years or younger who respond to first-line chemotherapy followed by high-dose combination alkylating agents (cyclophosphamide 5,625 mg/m2, cisplatin 165 mg/m2, and carmustine 480 mg/m2) with hematologic stem-cell support and chest and prophylactic cranial radiotherapy. PATIENTS AND METHODS: Patients were selected on the basis of their continued response to first-line therapy, their relative lack of significant comorbidity, and their ability to obtain financial clearance. RESULTS: Of 36 patients with stage III SCLC, nine patients (25%) had achieved a complete response (CR), 20 had achieved a near-CR, and seven had achieved a partial response before undergoing high-dose therapy. Toxicity included three deaths (8%). For all patients, the median PFS was 21 months. The 2- and 5-year survival rates after dose intensification were 53% (95% confidence interval [CI], 39% to 72%), and 41% (95% CI, 28% to 61%). Of the 29 patients who were in or near CR before undergoing high-dose therapy, 14 remain continuously progression-free a median of 61 months (range, 40 to 139 months) after high-dose therapy. Actuarial 2- and 5-year PFS rates were 57% (95% CI, 41% to 79%) and 53% (95% CI, 38% to 76%). By multivariate analysis, short intensive induction chemotherapy was associated with favorable outcome (P < .05). CONCLUSION: Use of high-dose systemic therapy with intensive local-regional radiotherapy was associated with manageable treatment-related morbidity and mortality. Patients who were in or near CR before intensification are enjoying an unmaintained 5-year PFS rate of 53%. Late complications were infrequent, and most patients returned to full-time work and activity. A randomized comparison of this approach and conventional-dose therapy should define the use of dose intensification with hematopoietic support in patients with responding limited-stage SCLC.

The interval between courses of chemotherapy have classically been kept to a minimum in order to maximize dose intensity. Certain clinical observations suggest that longer intervals, particularly in the high-dose setting, may be more effective. This is based in part on the evidence that resistance is reversible over time and that the interval should be sufficient to allow for such a reversal. Clinical evidence for such reversibility include the following. In metastatic breast cancer, double or double high-dose stem cell rescue (HD-SCR) studies involving a minimal interval, have not, at least as yet, been shown to be superior to single HD-SCR. In Hodgkin's disease, response after relapse correlates directly with duration of time to relapse. In a comparative study of metastatic breast cancer, early HD-SCR preceded by daunorubicin induction was inferior to delayed HD-SCR. The latter was not preceded by induction chemotherapy. In a comparative study of childhood ALL, patients randomized to delayed (4 month interval) intensification had a significantly superior survival as compared to patients randomized to immediate (1 month interval) intensification. Taken together, these clinical observations indicate that resistance is reversible and that optimization of the interval must take this into account. Cytokinetic modeling of those clinical studies also found that delayed HD-SCR could result in a superior effect. Cytokinetic models of minimal residual tumor which were also examined included the Skipper exponential model, the Norton-Simon model which emphasizes the Gompertzian effect, the clonal evolution model, and the Retsky-Demisheli model which derives from a bimodal relapse pattern above. Biological and clinical data have resulted in a clinical protocol in the CALGB wherein patients with metastatic breast cancer are randomly allocated to (1) a single HD-SCR arm; (2) a double HD-SCR with a 5-week interval; and (3) a double HD-SCR arm with a 16 week interval.

PURPOSE: We undertook a prospective, randomized phase III trial to evaluate the safety and efficacy of using a phase II agent before initiating therapy with standard combination chemotherapy in metastatic breast cancer patients. PATIENTS AND METHODS: A total of 365 women with measurable metastatic breast cancer, previously untreated with chemotherapy for their metastatic disease, were randomized to receive either immediate chemotherapy with cyclophosphamide, doxorubicin, and fluorouracil (CAF) or up to four cycles of one of five sequential cohorts of single-agent drugs: trimetrexate, melphalan, amonafide, carboplatin, or elsamitrucin, followed by CAF. RESULTS: The toxicity of each single agent followed by CAF was comparable to that of CAF alone. The cumulative response rates for the single agent followed by CAF were not statistically different from those of CAF alone (44% v 52%; P = .24). However, in the multivariate analysis, patients with visceral disease had a trend toward lower response rates on the phase II agent plus CAF arm (P = .078). Although survival and response duration also were not statistically significantly different between the two study arms (P = .074 and P = .069, respectively), there was a suggestion of benefit for the CAF-only arm. CONCLUSION: The brief use of a phase II agent, regardless of its efficacy, followed by CAF resulted in response rates, toxicities, durations of response, and survival statistically equivalent to those seen with the use of CAF alone. These findings support the use of a new paradigm for the evaluation of phase II agents in the treatment of patients with metastatic breast cancer.

Introduction : Neoadjuvant therapy in patients with Stage IIIA NSCLC is associated with a 50–70% resection rate and a 3–5 year survival of 20–32%, but few trials have required meticulous staging of the mediastinum to ensure homogeneity of the study population. Continuous infusion cisplatin 25 mg/m 2 /day 1–5, 5-fluorouracil 800 mg/m 2 /day 2–5, and high-dose leukovorin 500 mg/m 2 /day 1–5 (PFL) given every 4 weeks achieved a 41% response rate in metastatic NSCLC (lynch TJ, Kalish LA, Kass F, Strauss G, Elias A, Skarin A, Shulman L, Sugarbaker D, Frei E. Continuous infusion cisplatin, 5-fluorouracil, and leukovorin for advanced non-small cell lung cancer. Cancer 1994; 73: 1171–1176). The regimen was therefore evaluated in 34 patients with pathologic Stage IIIA N2 disease between 391 and 1092. Methods : Staging consisted of chest, liver, brain computerized tomography and bone scan, bronchoscopy and surgical mediastinal node mapping. Patients received PFL for 3 cycles, followed by thoracotomy and thoracic radiotherapy (TRT) to 54–60 Gy. Results : Median age was 57 (42–68) years. Demographic factors included: male 56%; adenocarcinoma 59%, squamous cell carcinoma 24%; Stage T3N2 26%, T2N2 56%, and T1N2 18%. No treatment related deaths occurred. Radiographically defined response to PFL was 65% (6% complete). Thoracotomy was performed in 28 patients (82%) (6 had no attempt due to disease progression). Complete resection was achieved in 21 (75%) and seven were unresectable. Pathologic complete response was observed in five patients (15%) and an additional unresectable patient had fibrosis-only documented at thoracotomy for an overall clinicopathologic response rate of 76% (18% pathologic CR). Another ten patients had residual primary with or without hilar disease with resolution of previously documented mediastinal involvement. Six (18%) patients remain alive and disease-free with a median follow-up of 46 (33–50) months, four of whom had achieved pathologic complete response at time of surgery. Conclusions : Long-term event-free survival was associated with complete surgical resection which in turn was associated with clinical response to chemotherapy. There was a possible trend associating pathologic downstaging (absent residual disease in mediastinal nodes), particularly pathologic complete response observed in patients with non-bulky mediastinal disease, with improved event-free survival. Pathologic downstaging might therefore be a useful surrogate endpoint in trials evaluating the preoperative activity of new chemotherapy regimens. While radiographic response generally correlated with findings at surgery, response as determined by histologic examination of resected tissue was generally more extensive and may more accurately reflect the systemic impact of the chemotherapy regimen.

While complete remission may be achieved in 65% of adults with de novo AML, such remissions lack durability when conventional post-remission therapy is administered. Uncontrolled trials have suggested that intensive post-remission therapy may prolong these responses. To assess this concept, the Cancer and Leukemia Group B administered induction therapy (cytarabine and daunoribucin) to 1088 adults (median age: 52 years). Of these 1088 patients, 693 (64%) achieved complete remission of whom 596 were randomly assigned to receive four courses of single-agent cytarabine in one of three dose schedules: 3 gm/m2 in a 3-h infusion every 12 h x 2 on days 1, 3, and 5 (HiDAc; 187 patients); 400 mg/m2 per day x 5 days continuous infusion (206 patients); or 100 mg/m2 per day x 5 days continuous infusion (203 patients). All patients then received four courses of monthly maintenance treatment. After a median follow-up time of 63.5 months, the three treatment cohorts had significantly different disease-free survivals (p = 0.001). The probability of remaining in continuous complete remission after 5 years for patients 60 years of age or younger was 42% for HiDAc, 29% for 400 mg/m2, and 19% for 100 mg/m2 (p = 0.0007). In contrast, for patients older than age 60 years, the probability of continuous complete remission after 4 years was 14% or less in each of the three cytarabine groups. With further maturation of the data, the outcome of this trial continues to support the concept of a doseresponse effect for cytarabine in patients with AML and 60 years of age or younger. The results observed with the HiDAc dose schedule in this age group are similar to those reported in patients with AML who undergo allogeneic or autologous bone marrow transplantation during first remission.

The Phase III clinical trial is a randomized, comparative, often multi-institutional study addressed to a quantitative question. It is the cadillac of clinical trials. When properly applied, it is highly effective in comparing new treatment and standard (control) therapy.

PURPOSE Twenty-one percent of responding metastatic breast cancer patients remain progression-free a median 50 months following one intensification cycle of cyclophosphamide (6,000 mg/m2), thiotepa (500 mg/ m2), and carboplatin (800 mg/m2) (CTCb) with autologous bone marrow transplantation (ABMT). This trial studied whether the sequence of high-dose melphalan followed by CTCb resulted in improved disease response and duration. METHODS Women with at least partial responses (PRS) to induction received melphalan (140 or 180 mg/ m2) with peripheral-blood progenitor cell (PBPC) and granulocyte colony-stimulating factor (G-CSF) support. They were monitored as outpatients. After recovery, patients were hospitalized for CTCb with marrow, PBPC, and G-CSF support. RESULTS Data on 67 women, at a median of 25 months from CTCb, were examined. After melphalan, 49 (73%) required admission for fever (89%), mucositis (35%), or infection (15%) (median stay, 8 days). All received CTCb. For the first 33 patients, the median days from start of melphalan to CTCb was 24. After liver toxicity (one death from venoocclusive disease [VOD]) developed in 11 patients during CTCb, the interval between intensifications was increased to 35 days without incident. Twenty-three patients (34%) are progression-free a median of 16 months post-CTCb. The median progression-free survival (PFS) and survival times for the whole group are estimated at 11 and 20 months, respectively. CONCLUSION Treatment with this sequence of high-dose melphalan followed by CTCb has not resulted in superior PFS to date, when compared with single-intensification CTCb. This report discusses factors related to patient selection, the role of induced drug resistance, and the schedule of administration of alkylating agenting that may adversely influence outcome.

The sensitivity for DNA adduct formation by antitumor alkylating agents (mechlorethamine, cisplatin and adozelesin) of the postlabeling technique and thin-layer chromatography was studied. Three DNAs were used: a double-stranded 20-bp oligonucleotide of defined sequence, calf thymus DNA and murine leukemia L1210 cellular DNA. With high concentrations of mechlorethamine, there was a marked decrease in normal dGp, a lesser decrease in dAp and dCp and no change in dTp. Using 2D mapping PEI-cellulose thin-layer chromatography analyses, it was found that six mechlorethamine: DNA adducts were produced after a short exposure to mechlorethamine. After an extended time at relatively high drug concentrations there was an alteration in the mechlorethamine: DNA adduct pattern that may reflect the conversion of monoadducts to crosslinked adducts. Similar observations were made with cisplatin and adozelesin. When murine leukemia L1210 cells were treated with 50 microM mechlorethamine or 50 microM cisplatin for 1 h, six or more mechlorethamine: DNA adducts and five cisplatin: DNA adducts were detected. After allowing 6 h. for repair of potentially lethal damage, several adducts were no longer detectable and others appeared with diminished intensity. Nuclease P(1) dephosphorylates normal nucleotides at relatively low enzyme concentrations with variation depending upon the nucleotide. In general, considerably lower concentrations of nuclease P1 were required to dephosphorylate the normal nucleotides than to dephosphorylate the antitumor alkylating agent: nucleotide adducts, thus allowing increased sensitivity of the postlabeling assay. The sensitivity of detection of antitumor alkylating agent: DNA adducts in DNA from treated L1210 cells approached one adduct per 10(7)-10(8) nucleotides. These results suggest that the postlabeling technique may be sufficiently sensitive and specific for the study of the clinically effective levels of antitumor alkylating agents.

Cyclophosphamide is a prodrug activated by cytochrome P450 isozymes in the liver. The product of hepatic activation of cyclophosphamide is 4-hydroxycyclophosphamide. Previously reported methods for determining 4-hydroxycyclophosphamide were either impractical or unreliable for monitoring infusion pharmacokinetics in conjunction with clinical trials. One procedure in which a fluorescent hydroxyquinoline derivative was prepared from 4-hydroxycyclophosphamide and analyzed by HPLC appeared to work at first, but gradually lost its selectivity due to degradation of the column by the strongly acidic mobile phase. An alternative procedure was developed using a weakly acidic eluent and postcolumn treatment with trifluoroacetic acid. This provided for protonation of the hydroxyquinoline, required for sensitive fluorescence detection, but spared the column. The resulting assay was sensitive, selective, reproducible, and accurate. The method was used to monitor 4-hydroxycyclophosphamide pharmacokinetics during and after 4 day infusions of 1.5 g/m2-day of cyclophosphamide given to three patients. It was also used to measure the time-dependent disappearance of acrolein and 4-hydroxycyclophosphamide added to human blood from healthy donors and that of metabolically derived 4-hydroxycyclophosphamide in the blood of a patient treated with cyclophosphamide. Slower decomposition was observed in the latter two cases than in the blood spiked with acrolein. Reliable data were obtained from > 1000 determinations using the same column without significant degradation of its stationary phase.