Phase I trial of combined immunotherapy with subcutaneous granulocyte macrophage colony-stimulating factor, low-dose interleukin 2, and interferon alpha in progressive metastatic melanoma and renal cell carcinoma.

The purpose of our study was to determine the maximally tolerated dose (MTD) and DLT of combined administration of granulocyte macrophage colony-stimulating factor (GM-CSF), low-dose interleukin 2 (IL-2) and IFN-alpha in patients with progressive metastatic melanoma or renal cell carcinoma (RCC). In addition, the activation and expansion of effector cells were measured. Cohorts of three patients were treated with increasing doses of IL-2 (1, 4, and 8 MIU/m2) and GM-CSF (2.5 and 5 microg/kg) with a constant dose of IFNalpha (5 million units) s.c. for 12 days every 3 weeks. An additional six patients were treated at the MTD. Immune activation was monitored during the first cycle. Response was evaluated after two cycles. The MTD was found to be 2.5 microg/kg GM-CSF, 4 MIU/m2 IL-2, and 5 mega units of IFNalpha. DLT was grade 4 fever, chills with hypotension, grade 3 fatigue/malaise, and fluid retention. Dose reduction of IL-2 to 2 MIU/m2 was necessary in three of nine patients who initially received the MTD. Treatment was initiated in the hospital but could be continued at home after 3-4 days. Significant increases in lymphocytes, (activated) T cells (CD4+ and CD8+), NK cells, monocyte DR expression, neutrophils, and eosinophils were found. CD8+ T-cell activation (sCD8) and NK cell expansion was mainly present in patients receiving 2 or 4 MIU/m2 IL-2. Of eight patients with progressive metastatic RCC after nephrectomy, three achieved a complete remission, and 1 of 7 patients with metastatic melanoma achieved a partial remission. In our study, the MTD of combined immunotherapy with GM-CSF, IL-2, and IFNalpha was established; DLT was: (a) grade 4 fever with hypotension needing i.v. fluid support; and (b) grade 3 fluid retention and/or fatigue/malaise. The scheme resulted in considerable expansion and/or activation of various effector cells. The complete responses in RCC patients are promising but need to be confirmed in Phase II studies.

Transposon Tc1 of the nematode Caenorhabditis elegans jumps in human cells.

The transposon Tc1 of the nematode Caenorhabditis elegans is a member of the widespread family of Tc1/mariner transposons. The distribution pattern of virtually identical transposons among insect species that diverged 200 million years ago suggested horizontal transfer of the elements between species. Thishypothesis gained experimental support when it was shown that Tc1 and later also mariner transposons could be made to jump in vitro , with their transposase as the only protein required. Later it was shown that mariner transposons from one fruit fly species can jump in other fruit fly species and in a protozoan and, recently, that a Tc1-like transposon from the nematode jumps in fish cells and that a fish Tc1-like transposon jumps in human cells. Here we show that the Tc1 element from the nematode jumps in human cells. This provides further support for the horizontal spread hypothesis. Furthermore, it suggests that Tc1 can be used as vehicle for DNA integration in human gene therapy.