W. Achterrath

PURPOSE AND METHODS: For more than three decades, the therapeutic options for patients with advanced colorectal cancer have almost exclusively been based on fluoropyrimidines. With the recognition that topoisomerase-I (TOP-I) is an important therapeutic target in cancer therapy, irinotecan, a semisynthetic TOP-I-interactive camptothecin derivative, has been clinically established in the treatment of colorectal cancer. RESULTS: Irinotecan was investigated as second-line chemotherapy after prior treatment with fluorouracil (FU)-based regimens in two large randomized phase III trials comparing irinotecan with either best supportive care or an infusional FU/leucovorin (LV) regimen. The outcomes of these trials established irinotecan as the standard therapy in the second-line treatment of colorectal cancer. The therapeutic value of irinotecan in the first-line treatment of metastatic colorectal cancer was investigated in two large randomized phase III trials comparing the combination of irinotecan and FU/LV with FU/LV alone. Both trials demonstrated significant superior efficacy for the combination of irinotecan and FU/LV in terms of response rate, median time to disease progression, and median survival time. Consequently, the combination of irinotecan and FU/LV has been approved as first-line chemotherapy for patients with metastatic colorectal cancer and constitutes the reference therapy against which other treatment options must be tested in the future. CONCLUSION: In this review, the clinical rationale and update of the present clinical status of irinotecan in the treatment of colorectal cancer and future prospects of irinotecan-based combinations are discussed.

Thirty-four patients with locally advanced, nonresectable gastric cancer (staged by laparotomy) received etoposide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (EAP). Thirty-three patients were evaluable for response and toxicity. Second-look surgery with removal of residual tumor by gastrectomy and lymphadenectomy was performed in case of complete/partial remission (CR/PR) after EAP. After successful resection (R0- and R1-resection), two cycles of EAP were administered for consolidation therapy. Patients refusing reoperation received up to six cycles of EAP. The response rate (CR/PR) after EAP was 70% (23/33), including a 21% (7/33) rate of clinical CRs (CCRs). Two patients had minor remission (MR)/no change and seven had progressive disease. There was one early death. Nineteen of 23 responders (5 CCRs, 14 clinical PRs [CPRs]) and one patient with MR underwent second-look surgery. Five CCRs were pathologically confirmed; 10 patients with CPR were without evidence of disease (NED) after resection. In three patients (CPR), R1-resections (microscopically tumor-cell positive proximal margin) were performed; two patients are disease-free, 22+ and 33+ months after consolidation chemotherapy. In two patients, the tumor was again considered nonresectable. Twenty patients were disease-free after EAP +/- surgery +/- consolidation chemotherapy. Toxicity was primarily hematologic. Leukopenia and thrombocytopenia of World Health Organization (WHO) grade 3 occurred in 30% and 9%, respectively and grade 4 in 18% and 9% of the patients, respectively. There was no increased peri- or postoperative morbidity. After a median follow-up of 20 months for disease-free patients, the relapse rate is 60% (12/20). The median survival time for all patients is 18 months and for disease-free patients 24 months. EAP is highly effective in locally advanced gastric cancer, and offers a chance for surgery with curative intention in patients with an otherwise fatal prognosis.

In this phase II multicenter trial, 67 evaluable patients with advanced measurable gastric carcinoma were treated with a combination of etoposide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (EAP). The overall response rate was 64%, including 21% complete responses (CRs). In 55 patients with metastatic disease, 31 responses (51%) including eight CRs (15%) were achieved. Responses were seen in all metastatic sites, but the response rate was lower in patients with peritoneal carcinomatosis. In 12 patients with locoregional disease, six CRs and six partial responses (PRs) were observed. Eight CRs (three and five in patients with metastatic and locoregional disease, respectively) were pathologically confirmed. The overall median response duration was 7 months; it was 16 months for patients achieving CR (22 months for pathologically confirmed CR [pCR]), and 6 months for PR. The median survival time for all patients was 9 months, for the patients who achieved CR 17 months, for pCR 23 months, and for PR 9.5 months. Median survival time for all patients with metastatic disease was 8 months, and for locoregional disease 12.5 months. Six patients (9%) (four local, two metastatic disease) were alive at 2 years, and four patients are alive and disease free at 35+ to 56+ months. Main toxicities were leukopenia and thrombocytopenia, with 64% of patients developing grade 3 to 4 myelosuppression and 12% severe infections. Nonhematologic toxicities of World Health Organization (WHO) grade 4 were not observed.

The recent successes being achieved with combination chemotherapy regimens, such as FAMTX (fluorouracil [5-FU], doxorubicin, methotrexate), EAP (etoposide, doxorubicin, cisplatin), and ELF (etoposide, leucovorin, 5-FU), strongly indicate that gastric cancer is chemosensitive. With these regimens, objective remission rates of more than 50% were recorded, including approximately 10% complete remissions (CRs). Moreover, some of these CRs were histopathologically confirmed. The finding that locally advanced disease (LAD) and technically unresectable disease could be rendered resectable by preoperative chemotherapy (EAP) was important. Thirty-six patients with LAD had been treated in a phase II trial with preoperative EAP, inducing 24 (70%) overall remissions (two clinical CRs, six pathologic CRs, 16 partial remissions [PRs] in 35 evaluable patients. Twenty-one patients were disease-free after chemotherapy with or without second-look surgery. The median survival time was 18 months for all patients and 24 months for disease-free patients. At 30+ months, 21% of all patients are still living disease-free. The expected survival of patients with unresectable LAD is approximately 4 to 6 months without any treatment and 6 to 9 months with standard chemotherapy. Compared with the latter results, the preoperative use of effective regimens (eg, EAP) seems to improve prognosis of patients with LAD. Moreover, such a multimodal approach may increase the number of long-term survivors among patients with resectable gastric cancer, especially those whose stage indicates a high risk of relapse (stages IIIa or IIIb). However, partly because of the severe toxicities (myelosuppression, nausea/vomiting), a considerable number of patients cannot be treated with these new regimens for the following reasons: Two of three patients with gastrointestinal disease are older than 60 years. Nontumorous diseases of the cardiovascular system, kidney, and others are frequent in this age group and may complicate or even prevent treatment with aggressive regimens. Considering the predominantly palliative treatment intentions in far advanced (metastasized) gastric cancer, regimens with low toxicities and acceptable activity should be preferred. For these reasons, we developed and investigated the combination ELF in a phase II trial in elderly patients (greater than 65 years) and in patients with cardiac risks who could not be treated with anthracyclines. The overall response rate in 51 evaluable patients was 53% (27 of 51) including six clinical CRs (12%). The median remission duration was 9.5 months and the median survival time was 11 months. Tolerability was excellent. Only 16% and 4% of patients, respectively, experienced WHO grades 3 and 4 leukopenia. Nausea/vomiting and mucositis/stomatitis were mild.(ABSTRACT TRUNCATED AT 400 WORDS)

From a single wild-type strain of Ehrlich ascites tumor, sublines resistant to daunorubicin, etoposide, and cis-diamminedichloroplatinum(II) have been developed in vivo. Different levels of resistance were achieved after 4 to 8 months for anthracyclines (greater than 32-fold), cis-diamminedichloroplatinum(II) (4-fold), and etoposide (greater than 6-fold). Anthracycline resistance was associated with decreased nuclear steady-state concentration of anthracyclines, increased content of high-molecular-weight membrane glycoproteins, and glucose-dependent drug extrusion after metabolic blockade with sodium azide. A similar "pump" system which was apparently not drug specific was also documented in etoposide resistance. Resistance towards cis-diamminedichloroplatinum(II) was accompanied by decreased cis-diamminedichloroplatinum(II)-induced DNA damage in vitro when proteinase K-resistant interstrand cross-links were measured by alkaline elution. Parallel in vivo studies revealed cross-resistance of various degrees among a number of anthracycline analogs, complete cross-resistance among daunorubicin, doxorubicin, and 4'-(9-acridinylamino)methanesulfon-M-anisidine (amsacrine), and partial cross-resistance between daunorubicin and etoposide. However, cis-diamminedichloroplatinum(II) was curative in anthracycline- and etoposide-resistant cells, as daunorubicin and etoposide were curative in acquired resistance towards cis-diamminedichloroplatinum(II). cis-Diamminedichloroplatinum(II) resistance was also overcome by the derivative 1,2,diaminocyclohexylplatinum malonate. The Vinca alkaloid vindesine, although only marginally active in the control tumor, was highly active in cells selected for cis-diamminedichloroplatinum(II) resistance. These in vivo patterns of cross-resistance and collateral sensitivity may be related to observations in clinical chemotherapy.