Abstract 4209: CD38KO K-NK cells prevent NK cell fratricide effect and improve isatuximab-mediated cytotoxicity against multiple myeloma cells

Multiple myeloma (MM) is a plasma cell malignancy characterized by clonal accumulation of malignant plasma cells in the bone marrow. CD38 is highly expressed on MM cells, and antibodies targeting CD38 (such as Isatuximab and Daratumumab) induce MM cell killing though several mechanisms, particularly by NK cell-mediated antibody dependent cellular cytotoxicity (ADCC). However, NK cells also express CD38 and treatment with anti-CD38 antibodies results in a rapid decrease of NK cells presumably due to fratricide, which may potentially limit NK cell mediated ADCC and reduce the efficacy of anti-CD38 antibody treatment. NK cells lacking CD38 in combination with Daratumumab have been shown to be resistant to NK cell fratricide and have improved ADCC. Here, we investigated the effect of knocking out CD38 in K-NK cells (CD38KO K-NK) in combination with Isatuximab. Peripheral blood NK cells were isolated from healthy donors and expanded using Kiadis PM21 particle technology (Oyer et al, Cytotherapy 2016) to produce highly activated K-NK cells. To produce CD38KO K-NK cells, CRISPR gene editing was applied during NK cell expansion by electroporating with Cas9/RNP complexes targeting CD38, and successful deletion of CD38 was confirmed by flow cytometry analysis. Analysis of key NK cell receptors by flow cytometry evidenced very similar receptor profiles between WT and CD38KO K-NK cells, suggesting that CD38 deletion does not affect the potent activation state of the K-NK cells. Importantly, CD38KO K-NK cells were found to be resistant to Isatuximab-induced fratricide. The cytotoxic activity of CD38KO K-NK cells in combination with Isatuximab against LP-1 and H929 MM cell lines was also measured. Calcein release assay and Incucyte based analysis revealed that cytotoxicity of CD38KO K-NK cells is enhanced in presence of Isatuximab, and that CD38KO K-NK cells are more cytotoxic than WT when combined with Isatuximab. Furthermore, the effect of Isatuximab/CD38KO K-NK cells combination also in association with SAR444245 (also termed THOR-707; Ptacin et al, Nat Commun 2021), an engineered non-α binding IL-2 that promotes NK cell activation and proliferation, was tested. Cytotoxicity of WT or CD38KO NK cells is enhanced in the presence of SAR444245. Indeed, addition of SAR444245 was found to further enhance the cytotoxic activity of CD38KO K-NK cells against LP-1 MM cells when combined with Isatuximab, resulting in an overall superior and sustained cytotoxicity. These data suggest that deletion of CD38 mitigates NK cell fratricide and improves Isatuximab-mediated ADCC against MM cells, and provide evidence for the therapeutic potential of the triple combination CD38KO NK cells, Isatuximab and SAR444245 in the setting of MM.

Citation Format: Marco Meloni, Pauline Perrin, Erik Slinger, Chrissta Maracle, Alain Fournier, Nicole Acuff, Jill Mooney, Robert Y. Igarashi, Angela Virone-Oddos, Marielle Chiron. CD38KO K-NK cells prevent NK cell fratricide effect and improve isatuximab-mediated cytotoxicity against multiple myeloma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4209.

481 Phase 1/2 study of THOR-707 (SAR444245), a pegylated recombinant non-alpha IL-2, as monotherapy and in combination with pembrolizumab or cetuximab in patients (pts) with advanced solid tumors

Background

THOR-707 (SAR444245) is a recombinant human IL-2 molecule irreversibly bound to a PEG chain to block alpha-binding while retaining near-native affinity for beta/gamma IL-2 receptor subunits. We report updated results from the ongoing HAMMER phase 1/2 trial.

Methods

SAR444245 was given via IV infusion as monotherapy Q2W [A] or Q3W [B], with pembrolizumab 200mg IV Q3W [C], or Q3W with cetuximab 400mg/m2 IV on D1 then 250mg/m2 IV QW [D] after pre-medication and peri-infusion hydration. A 3+3 design was used to identify the MTD/RP2D in pts with advanced solid tumors. Key objectives included assessments of safety, efficacy, pharmacokinetics (PK) and pharmacodynamics (PD).

Results

68 pts, median age 61.5 (37–78) yrs with median 3 (1–10) prior therapies enrolled. Most common tumors: melanoma (n=10), colorectal (n=11). Doses tested by cohort: [A]: 8–16 µg/kg (n=9); [B]: 8–40 µg/kg (n=29); [C]: 8–32 µg/kg (n=20); [D]: 16–24 µg/kg (n=10). The most common (>30%) AEs included pyrexia (52.5%), nausea (50.0%), flu-like symptoms (44.1%), vomiting (36.8%), chills (32.4%), fatigue (32.4%), AST elevation (30.9%). AEs generally resolved promptly with supportive care. Grade(G) 3/4 (>5%) related AEs included ALT/AST elevation (5.9%), and decreased lymphocyte count (26.5% within first 24 hrs, recovering by 48–72 hrs, this lymphocyte migration is mechanistically consistent with immune cell margination). G3/4 CRS was observed in 2 pts. Two DLTs occurred: G3 infusion reaction (32 µg/kg [B]) and G3 AST/ALT/G2 bilirubin elevation with G2 CRS (24 µg/kg [C]). No vascular leak syndrome, QTc prolongation, cardiac, or end organ toxicity was observed. Half-life was ~10 h. Sustained increases in CD8 T and NK cells were observed (fold relative to baseline): monotherapy (1–9.4x and 2–43.3x); with pembrolizumab (0.5–5.78x and 1.5–26.9x); with cetuximab (1.3–7.57x and 3.6–45.4x). Max CD4 and eosinophils increased to 136 cell/µL and 1078 cell/µL. No IL-5 elevation or ADAs were observed. Transient IL-6 increases in 4 pts (500, 627, 1000, 1100 pg/mL) were not associated with AEs. Four pts had confirmed PRs (1 PD1-treated SCC, unknown primary [B]; 2 PD1-naïve BCC and 1 PD1-treated HNSCC [C]); 3 pts had minor responses -- prostate (-24%) and PD1-treated melanoma (-17%) [B]; PD1-treated NSCLC (¬-29%) [C] -- after ≥2 scans. 23 pts completed ≥5 cycles.

Conclusions

SAR444245 was well tolerated and demonstrated antitumor activity in heavily pretreated patients, including prior checkpoint inhibitor therapy. Clinical safety, efficacy and PD suggest a wide therapeutic window. Combination with pembrolizumab and cetuximab leveraged SAR44245’s effects on CD8 T and NK cells.

Trial Registration

NCT04009681

Ethics Approval

The clinical trial was approved by each institutions ethics’ and review board prior to beginning study enrollment.

606 SAR444245 (THOR-707), an engineered non-alpha IL-2, enhances NK mediated antibody-dependent cellular cytotoxicity

Background

SAR444245 is a non-alpha IL-2 Synthorin TM molecule designed with a site-specific non-natural amino acid serving as a bioconjugation site for a single PEG. The non-natural amino acid is positioned to enable the PEG bioconjugation to obscure block binding to the IL-2 alpha receptor, while retaining near-native affinity with the intermediate affinity βγ IL-2 receptor. The non-alpha features of SAR444245 minimize activation of immune suppressive regulatory CD4+ T cells, while retaining activity on CD8+ T cells and NK cells expressing the IL-2 βγ receptors. NK cells exert anti-tumor activity through antibody dependent cellular cytotoxicity (ADCC) of IgG antibodies as well as antibody independent mechanisms.

Methods

Here, we utilized a panel of human primary PBMC based immunoassays and transcriptomic analysis to evaluate whether SAR444245 may improve ADCC function of IgG1 anti-tumor target antibodies.

Results

We characterized the ability of SAR444245 to enhance the cytolytic function of NK cells towards the prototypic NK target cell K562 as well as to modulate NK cell ADCC in combination with EGFR or CD20-targeting antibodies. In vitro assays demonstrated that SAR444245 can activate NK cells, promote NK cell proliferation and improve cytotoxicity of NK cells against K562 cells and across a panel of human EGFR and CD20 positive cell lines. In PBMC based ADCC assays with 1ug/ml of antibody, SAR444245 improved ADCC function maximally by 9-fold for an anti-EGFR antibody and at 5-fold for an anti-CD20 antibody. SAR444245 exhibited dose-dependent enhancement of NK cell ADCC function. Notably, this activity was observed in cell lines expressing varying levels of EGFR and CD20. SAR444245 treatment was associated with dose dependent increases in NK cell degranulation and IFN-γ production. Transcriptomic profiling revealed that SAR444245 had broad effects on NK cell biology leading to changes in inhibitory and activating receptors.

Conclusions

In summary, these results indicate that SAR444245 can enhance the cytolytic activity of NK cells and enhance the ADCC effect of tumor-directed antibodies by activating NK cells.

Tpl2 is required for neutrophil antimicrobial functions (INC6P.311)

Tumor progression locus 2 (Tpl2) is a serine/threonine kinase that promotes inflammatory cytokine production by activating the MEK/ERK pathway. Tpl2 has been shown to be important for the antimicrobial properties of macrophages. However, there is relatively little known about Tpl2’s contribution to neutrophil effector functions. This is an important consideration, since neutrophils provide the first line of defense against infection in the innate immune system. Gene expression analysis revealed that Tpl2 is highly expressed in both human and murine neutrophils, suggesting a potential function role for Tpl2 within this lineage. Despite a significantly higher proportion of bone marrow neutrophils in Tpl2-/- mice compared to wild type mice, Tpl2-/- mice had a significantly lower proportion of circulating neutrophils. In response to infection, neutrophils secrete inflammatory cytokines and produce reactive oxygen species (ROS). Tpl2 ablation impaired neutrophil TNF production in response to LPS stimulation and superoxide generation in response to fMLP, a chemotactic peptide. These results implicate Tpl2 in the regulation of multiple neutrophil antimicrobial pathways, including inflammatory cytokine secretion and oxidative burst. These studies suggest that Tpl2 functions very early during infection to bolster neutrophil-mediated innate immunity against extracellular bacteria, and current studies are evaluating the regulation of neutrophil-mediated bacterial killing by Tpl2.

Tumor progression locus 2 inhibits regulatory T cell development and immunosuppressive functions (LYM8P.640)

Regulatory T cells (Tregs) are a specialized subset of immunosuppressive T cells that function to maintain peripheral tolerance. We previously demonstrated that the serine-threonine kinase, tumor progression locus 2 (Tpl2, also designated Cot/Map3k8), regulates TCR signaling and inflammatory cytokine secretion in CD4+ T cells. Herein, we demonstrate that Tpl2 is preferentially expressed by Tregs and regulates their development and functions. Tpl2-/- mice exhibited increased proportions of thymic natural Tregs (nTregs) as well as peripheral splenic Tregs, in vivo. Enhanced Treg development was due to a T cell autonomous defect, since Treg development from tpl2-/- naïve T cells cultured in vitro was similarly enhanced, and peripheral Treg proportions were also increased within the tpl2-/- donor compartment of mixed bone marrow chimeras. This defect depended upon TCR signal strength and was enhanced at low antigen concentrations. Importantly, tpl2-/- Tregs had increased expression of the immunosupressive cytokines, IL-10 and IL-35, and provided better protection than wild-type Tregs in vivo in a T cell transfer model of colitis. These results demonstrate that Tpl2 has an important physiological role in limiting Foxp3 expression, Treg development and functions. Therefore, Tpl2 inhibition could potentially be used to deviate pathological immune responses in a variety of autoimmune diseases towards a protective, tolerogenic response through preferential Treg induction.

Tpl2 differentially regulates IFNγ and IL-17 production by CD4+ T cells in a T cell transfer model of colitis. (LYM8P.636)

Autoimmune diseases are approaching epidemic levels, estimated to affect 5-8% of the population. A number of autoimmune diseases are driven by autoreactive T cells, specifically T helper 1 (Th1) and T helper 17 (Th17) cells. One molecule gaining interest as a therapeutic target is the serine-threonine kinase, Tpl2, which promotes expression of proinflammatory mediators. We previously demonstrated that Tpl2 regulates Th1 differentiation, secretion of the inflammatory cytokine IFNγ, and host defense against the intracellular parasite Toxoplasma gondii. The goal of this study was to determine whether Tpl2 also regulates Th1 or Th17 differentiation in vivo in a T cell transfer model of colitis associated with mixed Th1/Th17 pathology. In vitro, Tpl2-/- naïve CD4+ T cells were impaired in IL-17A secretion under traditional Th17 inducing conditions of IL-6+TGF-β. Reduced IL-17A secretion correlated with increased expression of FoxP3, a transcription factor known to antagonize RORγt function. In vivo, transfer of Tpl2-/- T cells resulted in reduced proportions of CD4+ T cells expressing IFNγ, but not IL-17A, compared to that induced by wild type T cells. Further studies revealed that Th17 cells alternatively induced by IL-6+IL-23 was unaffected by Tpl2 deficiency. Collectively, these results implicate Tpl2 in TGF-β-induced FoxP3 expression. Additionally, they underscore the contribution of Tpl2 to Th1-dependent responses, including Th1-mediated immunopathology during autoimmunity.