Evaluation of thymosin α 1 in nonclinical models of the immune-suppressing indications melanoma and sepsis

Abstract

Objectives: Recent understanding of the complex pathophysiology of melanoma and severe sepsis suggests that immune-modulating compounds such as thymosin alpha 1 (INN: thymalfasin; abbreviated Ta1) could be useful in the treatment of these two unrelated immune-suppressing indications.

Research design and methods: Three nonclinical murine models were utilized, including: i) a lung metastasis B16 model; ii) a B16-based tumor growth model; and iii) a cecal-ligation and puncture (CLP) sepsis model.

Results: In the lung metastasis model, Ta1 treatment alone led to a 32% decrease in metastases (p < 0.05). Additionally, combinations of Ta1 and an anti-PD-1 antibody led to significantly fewer metastases than vehicle. In the tumor growth model, significant decreases in tumor growth were seen: 34% (p = 0.015) to 46% (p = 0.001) depending on the Ta1 dose. In the CLP sepsis model, Ta1 treatment showed a positive trend towards increased survival and decreased bacterial load. In this CLP model, Ta1 also appeared to have an effect on the levels of some biomarkers.

Conclusions: All three models demonstrated a benefit after treatment with Ta1, with no evidence of toxicity. These initial pilot studies support the hypothesis that immune-suppressive indications, including sepsis and melanoma, may be treated with Ta1 alone or by Ta1 in combination with other immunotherapies.

Keywords:

• anti-PD-1
• immunotherapy
• melanoma
• sepsis
• thymalfasin
• thymosin alpha 1

Declaration of interest

This paper is part of a supplemental issue, sponsored by SciClone. SciClone Pharmaceuticals, Inc., provided full funding for all studies performed and salaries or consultancy fees to authors. RS King is an employee of SciClone Pharmaceuticals, Inc. Cynthia Tuthill is a consultant for SciClone Pharmaceuticals, Inc. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.