Phase I study of emactuzumab single agent or in combination with paclitaxel in patients with advanced/metastatic solid tumors reveals depletion of immunosuppressive M2-like macrophages.

BACKGROUND: Emactuzumab is a monoclonal antibody against the colony-stimulating factor-1 receptor and targets tumor-associated macrophages (TAMs). This study assessed the safety, clinical activity, pharmacokinetics (PK) and pharmacodynamics (PD) of emactuzumab, as monotherapy and in combination with paclitaxel, in patients with advanced solid tumors. PATIENTS AND METHODS: This open-label, phase Ia/b study comprised two parts (dose escalation and dose expansion), each containing two arms (emactuzumab, every 2 or 3 weeks, as monotherapy or in combination with paclitaxel 80 mg/m2 weekly). The dose-escalation part explored the maximum tolerated dose and optimal biological dose (OBD). The dose-expansion part extended the safety assessment and investigated the objective response rate. A PK/PD analysis of serial blood, skin and tumor biopsies was used to explore proof of mechanism and confirm the OBD. RESULTS: No maximum tolerated dose was reached in either study arm, and the safety profile of emactuzumab alone and in combination does not appear to preclude its use. No patients receiving emactuzumab monotherapy showed an objective response; the objective response rate for emactuzumab in combination with paclitaxel was 7% across all doses. Skin macrophages rather than peripheral blood monocytes or circulating colony-stimulating factor-1 were identified as an optimal surrogate PD marker to select the OBD. Emactuzumab treatment alone and in combination with paclitaxel resulted in a plateau of immunosuppressive TAM reduction at the OBD of 1000 mg administered every 2 weeks. CONCLUSIONS: Emactuzumab showed specific reduction of immunosuppressive TAMs at the OBD in both treatment arms but did not result in clinically relevant antitumor activity alone or in combination with paclitaxel. (ClinicalTrials.gov Identifier: NCT01494688).

Sequential research-related biopsies in phase I trials: acceptance, feasibility and safety.

BACKGROUND: Sequential tumour biopsies are of potential interest for the rational development of molecular targeted therapies. PATIENTS AND METHODS: From June 2004 to July 2009, 186 patients participated in 14 phase I clinical trials in which sequential tumour biopsies (13 trials) and/or sequential normal skin biopsies (6 trials) were optional. All patients had to sign an independent informed consent for the biopsies. RESULTS: Tumour biopsies were proposed to 155 patients and 130 (84%) signed the consent while normal skin biopsies were proposed to 70 patients and 57 (81%) signed the consent. Tumour biopsies could not be carried out in 41 (31%) of the 130 consenting patients. Tumour biopsies were collected at baseline in 33 patients, at baseline and under treatment in 56 patients. Tumour biopsies were obtained using an 18-gauge needle, under ultrasound or computed tomography guidance. Only nine minor complications were recorded. Most tumour biopsy samples collected were intended for ancillary molecular studies including protein or gene expression analysis, comparative genomic hybridization array or DNA sequencing. According to the results available, 70% of the biopsy samples met the quality criteria of each study and were suitable for ancillary studies. CONCLUSIONS: In our experience, the majority of the patients accepted skin biopsies as well as tumour biopsies. Sequential tumour and skin biopsies are feasible and safe during early-phase clinical trials, even when patients are exposed to anti-angiogenic agents. The real scientific value of such biopsies for dose selection in phase I trials has yet to be established.