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Trastuzumab is a key component of treatment for human epidermal growth factor receptor 2 (HER2)-positive breast cancer in both the early and metastatic settings. It is administered intravenously, with between 17 and 52 infusions in standard regimens over 1 year. Intravenous administration of trastuzumab requires substantial time commitments for patients and health care professionals and can result in patient discomfort. A subcutaneous formulation of trastuzumab, containing recombinant human hyaluronidase to overcome subcutaneous absorption barriers, would reduce the administration duration and remove the need to establish intravenous access, thus improving the overall convenience of trastuzumab administration. This open-label, 2-part, phase I/Ib study (NCT00800436) was undertaken in healthy male volunteers and female patients with HER2-positive early breast cancer to identify the dose of subcutaneous trastuzumab that resulted in exposure comparable with the approved intravenous trastuzumab dose. A subcutaneous trastuzumab dose of 8 mg/kg was found to result in exposure comparable with the intravenous trastuzumab dose of 6 mg/kg. The subcutaneous formulation was well tolerated, with a trend toward fewer adverse events versus intravenous administration; most adverse events were mild in intensity. These results support an ongoing phase III efficacy and safety study comparing a fixed subcutaneous trastuzumab dose with intravenous trastuzumab administration.

The relaxin-like factor (RLF) is thought to be responsible for the intra-abdominal migration of the testis during mammalian development. Our latest studies of RLF and LGR8 have revealed that the N-terminal region of the A chain is not required for receptor binding but is indispensable for cyclic AMP generation. RLF derivatives with six residues deleted from the N terminus of the A chain are active, whereas further truncation, up to the first A chain cysteine (A-10), yields tightly binding ligands devoid of signaling activity. These derivatives are specific competitive inhibitors (RLFi) of RLF. Although receptor binding is dependent upon B chain residues, the N-terminal region of the A chain is a generic trigger of the trans-membrane signaling activity.The relaxin-like factor (RLF), 1 the product of the Insl3 gene (1), appears to be crucial for testicular descent in human neonates. Insl3Ϫ/Ϫ male mice retain the testes in the body cavity and are infertile (2, 3). The same phenotype was observed when the G-protein coupled receptor (GREAT) was deleted (4). These receptors (GREAT, LGR8) that affect the descent of testis in mice (4, 5) and in humans (LGR8) (6) are RLF-specific (7,8). Thus, an experimental system is now available that invites detailed investigation of the ligand/receptor interaction.RLF, isolated from bovine testes, consists of an A chain comprising 26 residues and a B chain of 40 or 45 residues. The chains are linked by three relaxin-like disulfide bonds (9). This native RLF confirms the structure that has been implied for all synthetic molecules. RLF binds its receptor in part through the B chain residue Trp(B-27) (10) and via additional, yet unidentified, residues that would account for the high receptor binding affinity. However, the molecule can be pared down without loss of binding avidity. Full binding intensity, for example, is observed with RLF ending in Trp(B-27)-amide (11).Our studies suggest that the N-terminal region of the A chain initiates the trans-membrane signal. Sequential shortening of the N-terminal end of the A chain reduces cAMP production, which becomes undetectable when 7 or more residues are removed. A chain truncations did not reduce binding avidity so that Ades-(1-7) RLF is a specific competitive inhibitor of RLF function. In this paper we report that the receptor-binding region of RLF is physically separate from the trans-membrane signal initiation site in the N-terminal region of the A chain. EXPERIMENTAL PROCEDURESMaterials-Fmoc amino acid derivatives were purchased from either Advanced ChemTech (Louisville, KY) or Novabiochem. Reagents and solvents for peptide synthesis were obtained from Advanced ChemTech. The LGR8 cloned into the pcDNA3.1.zeo plasmid was a gift from Dr. Hsueh, Department of Obstetrics and Gynecology, Stanford University School of Medicine. The human embryo kidney cell line 293T/17 was obtained from the American Type Culture Collection (ATCC CRL-11286) and used for LGR8 expression.Peptide Synthesis-All RLF chains were synthesized by Fmoc chemistry, usin...

According to Burkhardt et al. (Burkhardt, E., Adham, I. M., Brosig, B., Gastmann, A., Mattei, M. G., and Engel, W. (1994) Genomics 20, 13-19) Leydig cells contain the message for a protein of the insulin/relaxin family which was named Leydig cell insulin-like protein (LEY I-L). We have synthesized the human LEY I-L according to the amino acid sequence deduced from the published cDNA structure and obtained preliminary results concerning its potential target organs and its biological activity. Leydig cell insulin-like protein binds specifically to crude membrane preparations of mouse uterus and brain and shows cross-reactivity with the relaxin receptor, but not the insulin receptor. On the basis of these observations, together with the results of earlier structure-function considerations, we suggest that the new protein is a relaxin-like factor. By itself the new factor shows no obvious effect, but when given together with relaxin it significantly enhances relaxin-mediated widening of the mouse symphysis pubis.

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