Faculty Bibliography

BACKGROUND: Cancer chemotherapy with folate antimetabolites has been traditionally targeted at the enzyme dihydrofolate reductase and is based on the requirement of dividing tumor cells for a supply of thymidylate and purines. However, a new compound, 5,10-dideazatetrahydrofolate (DDATHF, whose 6R diastereomer is also known as Lometrexol), has become available that prevents tumor cell growth by inhibiting the first of the folate-dependent enzymes involved in de novo purine synthesis, glycinamide ribonucleotide formyltransferase. PURPOSE: We investigated the toxicity and therapeutic activity of DDATHF in a phase I clinical trial. METHODS: DDATHF was given at one of the following dose levels to 33 patients (16 females and 17 males) with malignant solid tumors: 3.0 mg/m2 per week (level A) to 10 patients, 4.5 mg/m2 per week (level B) to 13 patients, or 6.0 mg/m2 per week (level C) to 10 patients. Each drug cycle consisted of three weekly injections of DDATHF followed by a 2-week rest prior to redosing in the next cycle. RESULTS: Of 33 patients, 27 received at least one full cycle of DDATHF. Thrombocytopenia was the major dose-limiting toxicity, and it was severe in one of 10 patients during the first cycle and in two of four patients during the second cycle. Because of cumulative toxicity at 6.0 mg/m2, second or later cycles were abbreviated to two weekly doses. Stomatitis was generally mild, but it was dose-limiting in one patient. Neutropenia was infrequent and mild, and normocytic anemia requiring blood transfusion was common with repeat dosing. Leucovorin was given for grade 2 or greater thrombocytopenia and resulted in hematologic recovery within 1 week in all eight patients so treated. Without leucovorin, the thrombocytopenia lasted from 7 to 49 days in three patients. A partial response was noted in one patient with non-small-cell lung cancer and a minor response in one patient with breast cancer. Three patients with colorectal cancer achieved stable disease for greater than 3 months with improvement in carcinoembryonic antigen levels in one patient. CONCLUSIONS: DDATHF has an unusual pattern of toxicity with repetitive dosing, and humans with advanced cancer are considerably more sensitive than would be predicted from previous animal studies. Although doses of 6.0 mg/m2 per week on our schedule have been determined to be safe, repeated cycles require careful monitoring because of cumulative toxic effects. IMPLICATIONS: Additional phase I studies of DDATHF that relate toxicity to folate intake and tissue folate pools appear warranted.

Platinum compounds are universally recognized as one of the most important classes of chemotherapeutic agents for the treatment of cancer. Emergence of resistance to cisplatin has appeared, however, to be a major prognostic factor of adverse outcome in the otherwise most sensitive of malignancies: testicular and ovarian cancers. After a decade of testing both systemic and regional dose-intensification of cisplatin and its analog carboplatin--which is more amenable to dose escalation with cytokines and bone marrow progenitor cell support--a plateau is apparent even in sensitive tumor types beyond which additional dose escalations do not appreciably increase response. Laboratory work searching for causes of intrinsic and acquired resistance, providing early indication of drug sensitivity, and developing strategies for restoring or overcoming resistance is ongoing and is guiding clinical studies and drug development. Causes of cellular resistance to platinums are complex and include decreased drug accumulation, increased detoxification, increased repair of DNA-platinum adducts, and increased tolerance of DNA lesions. Clinical trials are already ongoing regarding strategies involving protection of specific toxicities, decreasing intracellular glutathione (by buthionine sulfoximine), decreasing DNA repair, and introducing new analogs that are able to overcome certain forms of platinum resistance.

PURPOSE: A clinical trial for patients with gastric cancer amenable to curative resection was undertaken to determine feasibility and response to preoperative systemic chemotherapy followed by postoperative intraperitoneal (IP) chemotherapy. METHODS AND MATERIALS: Thirty-eight patients with resectable gastric tumor received two cycles of protracted intravenous (IV)-infusion fluorouracil (5FU), 200 mg/m2/d, for 3 weeks with weekly IV leucovorin 20 mg/m2 and IV cisplatin 100 mg/m2 days 1 and 29. Resection of the gastric tumor followed within 3 weeks of completion of systemic chemotherapy. Those who had all visible tumor removed with clear margins received two cycles of IP floxuridine 3,000 mg (total dose) per day for 3 days and IP cisplatin 200 mg/m2 with IV sodium thiosulfate on the fourth day of IP therapy. RESULTS: Thirty-seven of 38 patients (97%) received two cycles of systemic chemotherapy. Thirty-five of 38 patients (92%) underwent laparotomy for gastric tumor resection. Thirty-three patients (87%) had gastric resections performed; 29 (76%) had all visible tumor removed with microscopically negative margins. No operative mortality was encountered. Twenty-six patients (68%) received IP treatment. IV neoadjuvant treatment was well tolerated and resulted in 68% of the patients reporting improvement in abdominal pain, 45% objective remissions by computed tomography (CT), 38% objective remissions by gastroscopy and biopsy, and 8% had complete surgical pathologic response. Neutropenic sepsis during the IP treatment phase contributed to the only treatment-related death. Four of 29 completely resected patients (14%) have had tumor recurrence. The median follow-up time of patients remaining alive is now 19 months. The median survival for 38 patients entered onto this protocol has not been reached at 17+ months. CONCLUSION: This novel approach to the treatment of adenocarcinoma of the stomach is feasible. The neoadjuvant systemic therapy results in significant primary tumor regression. The determination of whether systemic or IP components of the program contribute to decreased recurrence or increased survival awaits a prospectively randomized clinical trial.

We have extended our studies on the relationship between cisplatin/carboplatin-induced DNA damage in readily accessible tissue(s) and clinical response to therapy. Such an approach may assist in the study of cancer drug resistance and in establishing parameters for assessing human populations for sensitivity to DNA damaging agents in the environment. Platinum-DNA adduct levels were measured by atomic absorbance spectrometry. DNA repair capacity was assessed in human T-lymphocytes by the ability to repair cisplatin lesions in cellular DNA or in transfected plasmid DNA. In a "blinded" study of 21 patients receiving combination cisplatin/carboplatin drug therapy, there was a direct relationship between DNA damage in leukocytes and disease response (summary two-sided p = 0.00011). The cohort of patients had 15 different tumor types, suggesting that blood tissue and tumor tissue of an individual may process platinum-DNA damage similarly regardless of the tissue of origin of the tumor. In leukocytes in vivo, persistence and accumulation were prominent features of the cisplatin-DNA adduct profile. Functional DNA repair capacity has been studied in eight human leukocyte cell lines in vitro (three, T-cells; three, B-cells; one, monocytic; one, promyelocytic), using a host cell reactivation assay with cisplatin-damaged pRSVcat. In the three T cell lines studied, host cell reactivation efficiency was directly related to the cells' abilities to repair cisplatin-damaged cellular DNA (correlation coefficient = 0.993).(ABSTRACT TRUNCATED AT 250 WORDS)

This multi-center trial was carried out to assess the therapeutic potential of recombinant tumor necrosis factor (rTNF) as the first form of systemic therapy for advanced carcinomas of gastric and pancreatic origin. To be eligible patients were required to have no overt sign of coagulopathy and hepatic function studies with enzymes less than two times beyond the normal range. Twenty nine patients with gastric cancer and 26 with pancreatic cancer were entered from various institutions in the Southwest Oncology Group with 27 and 22, respectively, meeting eligibility criteria. Drug treatment consisted of rTNF (Genentech) given at a dose of 150 micrograms intravenously for five consecutive days every 3 weeks; 50% dose reduction was made for acute intolerance such as hypotension or severe fever and chills. Although eight patients with gastric cancer and five patients with pancreatic cancer received four or more courses of treatment, no objective antitumor responses were recorded. As in other trials common toxicities of rTNF included nausea and vomiting, chills and fever, hypotension, headache, myalgias, fatigue and malaise. However, in this trial, other toxicities became prominent: four episodes of symptomatic disseminated intravascular clotting occurred among patients with pancreatic cancer. Eleven with this disease and five with gastric cancer manifested laboratory findings of abnormal amounts of fibrin split products, and/or hypofibrinogenemia, and/or thrombocytopenia after treatment began. Other laboratory abnormalities that were commonly encountered included hyperglycemia, hypertriglyceridemia, anemia, neutropenia and an elevation in liver enzymes. We conclude that rTNF does not demonstrate antitumor efficacy against adenocarcinomas of the stomach and the pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)