Human macrophage biology research lags far behind that of mouse (1). In particular, we currently understand very little of the biology of tissue-specific macrophages in human.

Unsurprisingly, the cytokines that are critical for Macrophage development and maturation, namely, Macrophage colony-stimulating factor (M-CSF) and

Granulocyte macrophage colony-stimulating factor (GM-CSF), are the ones most intensively investigated as drugs.

Probably the most relevant candidate is GM-CSF because one drug has already been long approved.

Approved by the US FDA in 1991,recombinant yeast-derived GM-CSF (drug name Sargramostim) is used after autologous bone marrow transplantation to accelerate WBC (white blood cell) recovery.

Currently, several antibodies (Ab) and chemicals either targeting M-CSF or GM-CSF or the latter’s receptor are being tested in  clinical trials against Cancer, Cancer metastasis, CLE (cutaneous lupus erythematosus), MS (Multiple Sclerosis), RA (Rheumatoid Arthritis) (see Table below from 1). These are all in early phase (Phase I or II) so years away from being considered serious drug candidates let alone being approved.

Only one of these trials has peer-reviewed published results (as of Nov 2015), and that’s the 1st one listed, Trial NCT01023256. The candidate MOR103 showed promising safety and tolerance in a phase II trial on 85 RA patients (2). Most likely this drug candidate will move forward in clinical development.


  1. Wynn, Thomas A., Ajay Chawla, and Jeffrey W. Pollard. “Macrophage biology in development, homeostasis and disease.” Nature 496.7446 (2013): 445-455. Page on
  2. Hamilton, John A., and Adrian Achuthan. “Colony stimulating factors and myeloid cell biology in health and disease.” Trends in immunology 34.2 (2013): 81-89.
  3. Behrens, Frank, et al. “MOR103, a human monoclonal antibody to granulocyte–macrophage colony-stimulating factor, in the treatment of patients with moderate rheumatoid arthritis: results of a phase Ib/IIa randomised, double-blind, placebo-controlled, dose-escalation trial.” Annals of the rheumatic diseases (2014): annrheumdis-2013. results of a phase Ib/IIa randomised, double-blind, placebo-controlled, dose-escalation trial