Combined CD44- and CD25-Targeted Near-Infrared Photoimmunotherapy Selectively Kills Cancer and Regulatory T Cells in Syngeneic Mouse Cancer Models

Abstract

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed and selective cancer treatment that induces necrotic and immunogenic cell death and utilizes a mAb conjugated to a photo-absorber dye, IR700DX, activated by NIR light. Although CD44 is a surface cancer marker associated with drug resistance, anti-CD44-IR700 NIR-PIT results in inhibited cell growth and prolonged survival in multiple tumor types. Meanwhile, CD25targeted NIR-PIT has been reported to achieve selective and local depletion of FOXP3 þ CD25 þ CD4 þ regulatory T cells (Treg), which are primary immunosuppressive cells in the tumor microenvironment (TME), resulting in activation of local antitumor immunity. Combined NIR-PIT with CD44-and CD25-targeted agents has the potential to directly eliminate tumor cells and also amplify the immune response by removingTregs from the TME. We investigated the difference in therapeutic effects of CD44-targeted NIR-PIT alone, CD25-targeted NIR-PIT alone, and the combination of CD44-and CD25-targeted NIR-PIT in several syngeneic tumor models, including MC38-luc, LL/2, and MOC1. The combined NIR-PIT showed significant tumor growth inhibition and prolonged survival compared with CD44-targeted NIR-PIT alone in all tumor models and showed prolonged survival compared with CD25-targeted NIR-PIT alone in MC38-luc and LL/2 tumors. Combined CD44-and CD25-targeted NIR-PIT also resulted in some complete remissions. Therefore, combined NIR-PIT simultaneously targeting cancer antigens and immunosuppressive cells in the TME may be more effective than either type of NIR-PIT alone and may have potential to induce prolonged immune responses in treated tumors.

Near-infrared photoimmunotherapy targeting human-EGFR in a mouse tumor model simulating current and future clinical trials

“…Near-infrared photoimmunotherapy can concurrently destroy multiple cell types if multiple APCs are injected. For example, combined CD44-and CD25-targeted NIR-PIT has been shown to kill both cancer cells and Tregs, resulting in greater immune activation and inhibition of tumor growth than either therapy alone [13]. However, CD44 is expressed on both cancer cells and immune cells [5], thus, CD44-targeted NIR-PIT might reduce antitumor immunity and is, therefore, not an ideal model to analyze the additional effect of CD25-targeted NIR-PIT.…”

Interleukin-15 after Near-Infrared Photoimmunotherapy (NIR-PIT) Enhances T Cell Response against Syngeneic Mouse Tumors

“…Our previous study showed MOC1 tumor has low and more heterogeneous CD44 expression and CD44-targeted NIR-PIT was less effective against this type of tumor [ 13 ]. The NIR-PIT regimen and imaging protocol are depicted in Figure 4 A.…”

“…This report represents an extension of previous studies which attempt to augment the immune response initiated by NIR-PIT. For instance, a previous study demonstrated that the combination of CD44-targeted NIR-PIT and either immune checkpoint blockade or Treg-targeted NIR-PIT showed inconsistent therapeutic efficacy among these three tumor models [ 13 , 14 , 24 ]. CD44-targeted NIR-PIT in combination with other therapies showed promising results in MC38-luc and LL/2 but was less effective against MOC1 tumor which has low CD44 expression and fewer CD44 positive tumor cells compared to MC38-luc and LL/2.…”

“…High expression of CD44 is associated with tumor aggressiveness, drug resistance, and poor treatment outcome [ 11 , 12 ]. NIR-PIT using anti-CD44-mAb-IR700 induces effective tumor killing in CD44-expressing syngeneic mouse models [ 13 , 14 , 15 , 16 ]. Cell membrane rupture after NIR-PIT releases tumor-specific antigens into the TME and promotes dendritic cell (DC) maturation, resulting in presentation of cancer-specific antigens on DCs to naive T cells for priming [ 14 , 15 , 17 ].…”

Near-Infrared Photoimmunotherapy Combined with CTLA4 Checkpoint Blockade in Syngeneic Mouse Cancer Models

“…CD44 is a well-known marker of cancer stem cells [ 8 ] and anti-CD44-mAb-IR700 NIR-PIT induces effective tumor killing in CD44-expressing syngeneic mouse models [ 9 , 10 , 11 ]. Recently, the combination of CD44-targeted NIR-PIT and programmed cell death protein 1 (PD-1) immune checkpoint blockade was reported to induce massive tumor cell death and innate priming of polyclonal, cancer antigen-specific T-cell responses in several cancer models, resulting in complete tumor rejection and the generation of immunologic memory [ 10 ].…”