PCC0208018 exerts antitumor effects by activating effector T cells

Nobel Prize for immune checkpoint inhibitors, understanding the immunological switching between immunosuppression and autoimmunity

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are a revolutionary form of immunotherapy in cancer. However, the percentage of patients responding to therapy is relatively low, while adverse effects occur in a large number of patients. In addition, the therapeutic mechanisms of ICIs are not yet completely described.

AREAS COVERED

The initial view (articles published in PubMed, Scopus, Web of Science, etc.) was that ICIs increase tumor-specific immunity. Recent data (collected from the same databases) suggest that the ICIs pharmacotherapy actually extends beyond the topic of immune reactivity, including additional immune pathways, such as disrupting immunosuppression and increasing tumor-specific autoimmunity. Unfortunately, there is no clear delimitation between these specific autoimmune reactions that are therapeutically beneficial, and nonspecific autoimmune reactions/toxicity that can be extremely severe side effects.

EXPERT OPINION

Immune checkpoint mechanisms perform a non-selective immune regulation, maintaining a dynamic balance between immunosuppression and autoimmunity. By blocking these mechanisms, ICIs actually perform an immunological reset, decreasing immunosuppression and increasing tumor-specific immunity and predisposition to autoimmunity. The predisposition to autoimmunity induces both side effects and beneficial autoimmunity. Consequently, further studies are necessary to maximize the beneficial tumor-specific autoimmunity, while reducing the counterproductive effect of associated autoimmune toxicity.

Comparison study of different indoleamine-2,3 dioxygenase inhibitors from the perspective of pharmacodynamic effects

Introduction:

Indoleamine 2,3-dioxygenase (IDO) was a potential tumor immunotherapy target. IDO inhibitors showed inconsistent results in clinical trials, but no preclinical comparative study was reported. The purpose of this study was to evaluate the differences of representative IDO inhibitors (PCC0208009, INCB024360, NLG919) from the pharmacological perspective.

Methods:

In vitro experiments included: inhibition effects on IDO activity in cell and enzyme-based assay, effects on IDO expression in HeLa cells, and enhancement of proliferation and activation of peripheral blood mononuclear cell (PBMC). In vivo experiments included: pharmacokinetics and tumor distribution in CT26-bearing mice, effects on Kyn/Trp and anti-tumor effect and immunological mechanism in CT26 and B16F10 tumor-bearing mice.

Results:

Compared with INCB024360 and NLG919, PCC0208009 effectively inhibited IDO activity at lower dose 2 nM and longer duration more than 72 h, had higher enhancements on PBMC proliferation and activation, and could inhibit the IDO expression in Hela cells. The pharmacokinetics characteristics of three IDO inhibitors were similar in CT26-bearing mice. In CT26 and B16F10 tumor-bearing mice, PCC0208009 and INCB024360 had similar effects in Kyn/Trp reduction, and more potent than NLG919; three IDO inhibitors had similar effects in tumor suppression, changes of the percentages of CD3⁺CD8⁺ and CD3⁺CD4⁺ T cells, and activation of tumor infiltrating lymphocytes, while PCC0208009 had a better tendency than INCB024360 and NLG919.

Conclusion:

PCC0208009, INCB024360, and NLG919 were all effective IDO inhibitors, but the comprehensive pharmacological activity of PCC0208009 was better than INCB024360 and NLG919, which was basically consistent with the results or progresses of clinical trials.

Dihydroartemisinin Induces Growth Arrest and Overcomes Dexamethasone Resistance in Multiple Myeloma

The discovery of artemisinin (ART) for malaria treatment won the 2015 Nobel Prize in Medicine, which inspired the rediscovery and development of ART for the treatment of other diseases including cancer. In this study, we investigated the potential therapeutic effect of ART and dihydroartemisinin (DHA) on multiple myeloma (MM) cells including primary MM cells and in 5TMM3VT mouse model. Both in vitro and in vivo experiments showed that DHA might be a more promising anti-MM agent with significantly improved efficacy compared to ART. Mechanistic analyses suggested that DHA activated the mitochondrial apoptotic pathway by interacting with ferrous (Fe²⁺) ions and oxygen to produce reactive oxygen species (ROS). Intriguingly, DHA could reverse the upregulated expression of B-cell lymphoma 2 (Bcl-2) protein, a typical mitochondrial apoptotic marker, induced by dexamethasone (Dexa) in MM. We further demonstrated that DHA treatment could overcome Dexa resistance and enhance Dexa efficacy in MM. Additionally, DHA combined with Dexa resulted in increased ROS production and cytochrome C translocation from the mitochondria to the cytoplasm, resulting in alterations to the mitochondrial membrane potential and caspase-mediated apoptosis. In summary, our study demonstrated that DHA was superior to ART in MM treatment and overcame Dexa resistance both in vitro and in vivo, providing a promising therapeutic strategy for MM therapy.