Dose-escalation trial of M195 labeled with iodine 131 for cytoreduction and marrow ablation in relapsed or refractory myeloid leukemias.

PURPOSE: Mouse monoclonal antibody (mAb) M195 (anti-CD33) is reactive with most myeloid leukemia cells, monocytes, and hematopoietic progenitors, but not with other hematopoietic cells or stem cells nor with nonhematopoietic human tissues. A therapeutic dose-escalation study of M195 labeled with iodine 131 was conducted in patients with relapsed or refractory myeloid leukemias. METHODS: Twenty-four patients (16 relapsed or refractory acute myeloid leukemias, five blastic myelodysplastic syndromes [MDS], two chemotherapy-related secondary leukemias, and one blastic chronic myelogenous leukemia [CML]), including seven who had failed to respond to prior bone marrow transplantation (BMT), received from 50 mCi/m2 to 210 mCi/m2 of 131I-M195 in divided doses. RESULTS: In 22 patients, whole-body gamma-imaging demonstrated marked uptake of antibody into all areas of bone marrow. Twenty-three patients (96%) demonstrated decreases in peripheral-blood cell counts, with decreased percentage of bone marrow blasts seen in 83% of cases. Eighty-nine percent of bone marrow biopsies examined quantitatively demonstrated substantial decreases in the number of blasts, with greater than 99% of blasts killed in some patients. The two cases that failed to demonstrate leukemic cytoreduction occurred in the first two dose levels. For 131I doses of 135 mCi/m2 or greater, pancytopenia was profound and lasted for at least 12 days. Eight patients had sufficient marrow cytoreduction to proceed to BMT. Three of these achieved marrow remission, one of 6+, and one of 9 months' duration. Two patients in blastic phase temporarily reverted to their original myelodysplastic states. Thirty-seven percent of assessable patients developed human anti-mouse antibody (HAMA). In two patients with HAMA who were re-treated, plasma 131I-M195 levels could not be maintained and no therapeutic effect resulted. Significant nonhematologic toxicity (hepatic) was seen in one patient and the maximum-tolerated dose (MTD) was not reached. CONCLUSION: These data suggest that safe leukemic cytoreduction can be achieved with 131I-M195 even in multiply relapsed or chemotherapy-refractory leukemias. This agent may be useful as part of a preparative regimen for BMT.

A phase II trial of high-dose cisplatin and dacarbazine. Lack of efficacy of high-dose, cisplatin-based therapy for metastatic melanoma.

Cisplatin and dacarbazine are used widely in the treatment of metastatic melanoma. To evaluate high-dose cisplatin and dacarbazine, 32 patients with metastatic melanoma were treated with cisplatin 50 mg/m2 and dacarbazine 350 mg/m2 daily for three days repeated at 28-day intervals. Their median age was 43.5 years (range, 25 to 73 years), and their median Karnofsky performance status was 80% (range, 70% to 100%). Measurable and evaluable disease sites (number of patients) included lymph nodes (22), lung (17), soft tissue (16), liver (13), bone (seven), spleen (four), adrenal gland (three), skin (three), and other sites (five). Patients received a median of two cycles of therapy (range, one to eight cycles). Thirty patients were evaluable for response. No complete responses were observed. Five patients had a partial response (17%; 95% confidence interval, 3% to 30%) for 16+, 12+, 7, 6.5, and 3 months. Responding sites of disease included lymph nodes (five of 22), lung (three of 17), and soft tissue (two of 16). Hematologic toxicity (Grade greater than or equal to 3) included neutropenia (16 of 32 patients, 30 of 90 cycles), thrombocytopenia (eight of 32 patients, 12 of 90 cycles), and anemia (five patients). Nine episodes of neutropenia and fever were seen in four patients; two had bacteremia. Nonhematologic toxicity (Grade greater than or equal to 3) included hypotension (two patients), nausea and vomiting (four), neuropathy (two), ototoxicity (four), and hypomagnesemia (nine). The low objective response rate and severe toxicity of this regimen preclude its standard use in patients with metastatic melanoma. A review of cisplatin-based therapy in metastatic melanoma suggests that there is no dose-response relationship. The use of high-dose cisplatin (greater than 100 mg/m2) in the treatment of metastatic melanoma is not recommended.

Differing patterns of cytotoxicity of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate in various human cell strains.

Inhibition of colony formation by the phorbol ester tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) over a wide range of concentrations (10(-4)-10(2) ng/ml) was examined in two normal human diploid fibroblast strains and eight cell lines derived from various human tumors. Three dose-response patterns were observed: (i) no killing at any dose, which is characteristic of rodent cells; (ii) increasing cytotoxicity with TPA doses of 0.1 ng/ml or greater; and (iii) a biphasic response with maximal cytotoxicity at 1.0 ng/ml, and minimal effects at much lower or higher concentrations. The latter response group included both normal and tumor cell strains. When normal cells were incubated concurrently with superoxide dismutase or CuDIPS, survival was enhanced in a dose-dependent manner. Specific binding of [3H]PDBu to cells from each of the three response categories was studied to determine whether the cells might contain two classes of specific phorbol ester receptors. Scatchard plots yielded straight lines, consistent with one class of binding sites. The possible significance of this cytotoxic effect of TPA in human cells at dose levels usually considered typical for specific phorbol ester responses is discussed.