PRECAUTIONS General The serious complication of excessive thiotepa therapy, or sensitivity to the effects of thiotepa, is bone-marrow depression. If proper precautions are not observed thiotepa may cause leukopenia, thrombocytopenia, and anemia. Information for Patients The patient should notify the physician in the case of any sign of bleeding (epistaxis, easy bruising, change in color of urine, black stool) or infection (fever, chills) or for possible pregnancy to patient or partner. Effective contraception should be used during thiotepa therapy if either the patient or the partner is of childbearing potential. Laboratory Tests The most reliable guide to thiotepa toxicity is the white blood cell count. If this falls to 3000 or less, the dose should be discontinued. Another good index of thiotepa toxicity is the platelet count; if this falls to 150,000, therapy should be discontinued. Red blood cell count is a less accurate indicator of thiotepa toxicity. If the drug is used in patients with hepatic or renal damage (see CONTRAINDICATIONS section), regular assessment of hepatic and renal function tests are indicated. Drug Interactions It is not advisable to combine, simultaneously or sequentially, cancer chemotherapeutic agents or a cancer chemotherapeutic agent and a therapeutic modality having the same mechanism of action. Therefore, thiotepa combined with other alkylating agents such as nitrogen mustard or cyclophosphamide or thiotepa combined with irradiation would serve to intensify toxicity rather than to enhance therapeutic response. If these agents must follow each other, it is important that recovery from the first agent, as indicated by white blood cell count, be complete before therapy with the second agent is instituted. Other drugs which are known to produce bone-marrow depression should be avoided. Carcinogenesis, Mutagenesis, Impairment of Fertility Also see WARNINGS section. Carcinogenesis In mice, repeated IP administration of thiotepa (1.15 or 2.3 mg/kg three times per week for 52 or 43 weeks, respectively) produced a significant increase in the combined incidence of squamous-cell carcinomas of the skin, preputial gland, and ear canal, and combined incidence of lymphoma and lymphocytic leukemia. In other studies in mice, repeated IP administration of thiotepa (4 or 8 mg/kg three times per week for 4 weeks followed by a 20 week observation period or 1.8 mg/kg three times per week for 4 weeks followed by a 35 week observation period) resulted in an increased incidence of lung tumors. In rats, repeated IP administration of thiotepa (0.7 or 1.4 mg/kg three times per week for 52 or 34 weeks, respectively) produced significant increases in the incidence of squamous-cell carcinomas of the skin or ear canal, combined hematopoietic neoplasms, and uterine adenocarcinomas. Thiotepa given intravenously (IV) to rats (1 mg/kg once per week for 52 weeks) produced an increased incidence of malignant tumors (abdominal cavity sarcoma, lymphosarcoma myelosis, seminoma, fibrosarcoma, salivary gland hemangioendothelioma, mammary sarcoma, pheochromocytoma) and benign tumors. The lowest reported carcinogenic dose in mice (1.15 mg/kg, 3.68 mg/m2) is approximately 7-fold less than the maximum recommended human therapeutic dose based on body-surface area. The lowest reported carcinogenic dose in rats (0.7 mg/kg, 4.9 mg/m2) is approximately 6-fold less than the maximum recommended human therapeutic dose based on body-surface area. Mutagenesis Thiotepa was mutagenic in in vitro assays in Salmonella typhimurium, E coli, Chinese hamster lung and human lymphocytes. Chromosomal aberrations and sister chromatid exchanges were observed in vitro with thiotepa in bean root tips, human lymphocytes, Chinese hamster lung, and monkey lymphocytes. Mutations were observed with oral thiotepa in mouse at doses > 2.5 mg/kg (8 mg/m2). The mouse micronucleus test was positive with IP administration of > 1 mg/kg (3.2 mg/m2). Other positive in vivo chromosomal aberration or mutation assays included Drosophila melanogaster, Chinese hamster marrow, murine marrow, monkey lymphocyte, and murine germ cell. Impairment of Fertility Thiotepa impaired fertility in male mice at PO or IP doses ≥ 0.7 mg/kg (2.24 mg/m2), approximately 12-fold less than the maximum recommended human therapeutic dose based on body-surface area. Thiotepa (0.5 mg) inhibited implantation in female rats when instilled into the uterine cavity. Thiotepa interfered with spermatogenesis in mice at IP doses ≥ 0.5 mg/kg (1.6 mg/m2), approximately 17-fold less than the maximum recommended human therapeutic dose based on body-surface area. Thiotepa interfered with spermatogenesis in hamsters at an IP dose of 1 mg/kg (4.1 mg/m2), approximately 7-fold less than the maximum recommended human therapeutic dose based on body-surface area. Pregnancy Teratogenic Effects- Category D See WARNINGS section. Thiotepa can cause fetal harm when administered to a pregnant woman. Thiotepa given by the IP route was teratogenic in mice at doses ≥ 1 mg/kg (3.2 mg/m2), approximately 8-fold less than the maximum recommended human therapeutic dose based on body-surface area. Thiotepa given by the IP route was teratogenic in rats at doses ≥3 mg/kg (21 mg/m2), approximately equal to the maximum recommended human therapeutic dose based on body-surface area. Thiotepa was lethal to rabbit fetuses at a dose of 3 mg/kg (41 mg/m2), approximately 2 times the maximum recommended human therapeutic dose based on body-surface area. Patients of childbearing potential should be advised to avoid pregnancy. There are no adequate and well-controlled studies in pregnant women. If thiotepa is used during pregnancy, or if pregnancy occurs during thiotepa therapy, the patient and partner should be apprised of the potential hazard to the fetus. Nursing Mothers It is not known whether thiotepa is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for tumorigenicity shown for thiotepa in animal studies, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Pediatric Use Safety and effectiveness in pediatric patients have not been established. Geriatric Use Clinical studies of thiotepa did not include sufficient numbers of subjects aged 65 and over to determine whether elderly subjects respond differently from younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreasing hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.