Discovery and Characterization of ZL-2201, a Potent, Highly Selective, and Orally Bioavailable Small-molecule DNA-PK Inhibitor.

DNA-dependent protein kinase (DNA-PK), a driver of the non-homologous end-joining (NHEJ) DNA damage response pathway, plays an instrumental role in repairing double-strand breaks (DSB) induced by DNA-damaging poisons. We evaluate ZL-2201, an orally bioavailable, highly potent, and selective pharmacologic inhibitor of DNA-PK activity, for the treatment of human cancerous malignancies. ZL-2201 demonstrated greater selectivity for DNA-PK and effectively inhibited DNA-PK autophosphorylation in a concentration- and time-dependent manner. Initial data suggested a potential correlation between ataxia-telangiectasia mutated (ATM) deficiency and ZL-2201 sensitivity. More so, ZL-2201 showed strong synergy with topoisomerase II inhibitors independent of ATM status in vitro. In vivo oral administration of ZL-2201 demonstrated dose-dependent antitumor activity in the NCI-H1703 xenograft model and significantly enhanced the activity of approved DNA-damaging agents in A549 and FaDu models. From a phosphoproteomic mass spectrometry screen, we identified and validated that ZL-2201 and PRKDC siRNA decreased Ser108 phosphorylation of MCM2, a key DNA replication factor. Collectively, we have characterized a potent and selective DNA-PK inhibitor with promising monotherapy and combinatory therapeutic potential with approved DNA-damaging agents. More importantly, we identified phospho-MCM2 (Ser108) as a potential proximal biomarker of DNA-PK inhibition that warrants further preclinical and clinical evaluation. Significance: ZL-2201, a potent and selective DNA-PK inhibitor, can target tumor models in combination with DNA DSB-inducing agents such as radiation or doxorubicin, with potential to improve recurrent therapies in the clinic.

Allogeneic chimeric antigen receptor-T cells with CRISPR-disrupted programmed death-1 checkpoint exhibit enhanced functional fitness.

BACKGROUND AIMS: Therapeutic disruption of immune checkpoints has significantly advanced the armamentarium of approaches for treating cancer. The prominent role of the programmed death-1 (PD-1)/programmed death ligand-1 axis for downregulating T cell function offers a tractable strategy for enhancing the disease-modifying impact of CAR-T cell therapy. METHODS: To address checkpoint interference, primary human T cells were genome edited with a next-generation CRISPR-based platform (Cas9 chRDNA) by knockout of the PDCD1 gene encoding the PD-1 receptor. Site-specific insertion of a chimeric antigen receptor specific for CD19 into the T cell receptor alpha constant locus was implemented to drive cytotoxic activity. RESULTS: These allogeneic CAR-T cells (CB-010) promoted longer survival of mice in a well-established orthotopic tumor xenograft model of a B cell malignancy compared with identically engineered CAR-T cells without a PDCD1 knockout. The persistence kinetics of CB-010 cells in hematologic tissues versus CAR-T cells without PDCD1 disruption were similar, suggesting the robust initial debulking of established tumor xenografts was due to enhanced functional fitness. By single-cell RNA-Seq analyses, CB-010 cells, when compared with identically engineered CAR-T cells without a PDCD1 knockout, exhibited fewer Treg cells, lower exhaustion phenotypes and reduced dysfunction signatures and had higher activation, glycolytic and oxidative phosphorylation signatures. Further, an enhancement of mitochondrial metabolic fitness was observed, including increased respiratory capacity, a hallmark of less differentiated T cells. CONCLUSIONS: Genomic PD-1 checkpoint disruption in the context of allogeneic CAR-T cell therapy may provide a compelling option for treating B lymphoid malignancies.

ZL-1211 Exhibits Robust Antitumor Activity by Enhancing ADCC and Activating NK Cell-mediated Inflammation in CLDN18.2-High and -Low Expressing Gastric Cancer Models.

CLDN18.2 (Claudin18.2)-targeting therapeutic antibodies have shown promising clinical efficacy in approximately 30% of gastric cancers expressing high levels of CLDN18.2 and less pronounced activity in low expressing malignancies. Here, we report that ZL-1211 is a mAb targeting CLDN18.2 engineered to promote enhanced antibody-dependent cellular cytotoxicity (ADCC) with the goal of achieving more potent activity in a wider spectrum of high- and low-CLDN18.2 expressing tumors. ZL-1211 demonstrated more robust in vitro ADCC activity than clinical benchmark not only in CLDN18.2-high but also CLDN18.2-low expressing gastric tumor cell lines. Greater antitumor efficacy was also observed in mouse xenograft models. Natural killer (NK) cell played critical roles in ZL-1211 efficacy and NK-cell depletion abrogated ZL-1211-mediated ADCC activity in vitro. ZL-1211 efficacy in vivo was also dependent on the presence of an NK compartment. Strikingly, NK cells strongly induced an inflammatory response in response to ZL-1211 treatment, including increased IFNγ, TNFα, and IL6 production, and were recruited into tumor microenvironment in patient-derived gastric tumors expressing CLDN18.2 upon ZL-1211 treatment to lyse the tumor cells. Taken together, our data suggest that ZL-1211 more effectively targets CLDN18.2-high gastric cancers as well as -low expressing malignancies that may not be eligible for treatment with the leading clinical benchmark by inducing enhanced ADCC response and activating NK cells with robust inflammation to enhance antitumor efficacy. Clinical activity of ZL-1211 is currently under evaluation in a phase I clinical trial (NCT05065710). Significance: ZL-1211, anti-CLDN18.2 therapeutic antibody can target CLDN18.2-high as well as -low gastric cancers that may not be eligible for treatment with clinical benchmark. ZL-1211 treatment induces NK-cell activation with robust inflammation to further activate antitumor immunity in tumor microenvironment.

Differential selectivity of JAK2 inhibitors in enzymatic and cellular settings.

Small molecule inhibitors of Janus kinase (JAK) family members (JAK1, JAK2, JAK3, and Tyk2) are currently being pursued as potential new modes of therapy for a variety of diseases, including the inhibition of JAK2 for the treatment of myeloproliferative disorders. Selective inhibition within the JAK family can be beneficial in avoiding undesirable side effects (e.g., immunosuppression) caused by parallel inhibition of other JAK members. In an effort to design an assay paradigm for the development of JAK2 selective inhibitors, we investigated whether compound selectivity differed between cellular and purified enzyme environments. A set of JAK2 inhibitors was tested in a high-throughput JAK family cell assay suite and in corresponding purified enzyme assays. The high-throughput JAK cell assay suite comprises Ba/F3 cells individually expressing translocated ETS leukemia (TEL) fusions of each JAK family member (TEL-JAK Ba/F3) and an AlphaScreen phosphorylated-STAT5 (pSTAT5) immunoassay. Compound potencies from the TEL-JAK Ba/F3 pSTAT5 assays were similar to those determined in downstream cell proliferation measurements and more physiologically relevant cytokine-induced pSTAT5 PBMC assays. However, compound selectivity data between cell and purified enzyme assays were discrepant because of different potency shifts between cell and purified enzyme values for each JAK family member. For any JAK small molecule development program, our results suggest that relying solely on enzyme potency and selectivity data may be misleading. Adopting the high-throughput TEL-JAK Ba/F3 pSTAT5 cell assay suite in lead development paradigms should provide a more meaningful understanding of selectivity and facilitate the development of more selective JAK inhibitors.

Improved oral delivery of N-(4-hydroxyphenyl)retinamide with a novel LYM-X-SORB organized lipid complex.

PURPOSE: Fenretinide [N-(4-hydroxyphenyl)retinamide (4-HPR)] is a cytotoxic retinoid that suffers from a wide interpatient variation in bioavailability when delivered orally in a corn oil capsule. The poor bioavailability of the capsule formulation may have limited responses in clinical trials, and the large capsules are not suitable for young children. To support the hypothesis that a novel organized lipid matrix, LYM-X-SORB, can increase the oral bioavailability of fenretinide, fenretinide in LYM-X-SORB matrix and in a powderized LYM-X-SORB formulation was delivered to mice. EXPERIMENTAL DESIGN: Fenretinide was delivered orally to mice as the contents of the corn oil capsule, in LYM-X-SORB matrix (4-HPR/LYM-X-SORB matrix) or in a LYM-X-SORB matrix powderized with sugar and flour (4-HPR/LYM-X-SORB oral powder). Levels of 4-HPR, and its principal metabolite, N-(4-methoxyphenyl)retinamide, were assayed in plasma and tissues. RESULTS: In a dose-responsive manner, from 120 to 360 mg/kg/d, delivery to mice of 4-HPR in LYM-X-SORB matrix, or as 4-HPR/LYM-X-SORB oral powder, increased 4-HPR plasma levels up to 4-fold (P<0.01) and increased tissue levels up to 7-fold (P<0.01) compared with similar doses of 4-HPR delivered using capsule contents. Metabolite [N-(4-methoxyphenyl)retinamide] levels mirrored 4-HPR levels. Two human neuroblastoma murine xenograft models showed increased survival (P<0.03), when treated with 4-HPR/LYM-X-SORB oral powder, confirming the bioactivity of the formulation. CONCLUSIONS: 4-HPR/LYM-X-SORB oral powder is a novel, oral drug delivery formulation, suitable for pediatric use, which warrants further development for the delivery of fenretinide in the treatment of cancer. A phase I clinical trial in pediatric neuroblastoma is in progress.

Liquid chromatography method for quantifying D-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (D-threo-PPMP) in mouse plasma and liver.

A high-performance liquid chromatography (HPLC) method was developed to measure levels of d-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (d-threo-PPMP) in mouse plasma and liver. d-threo-PPMP was measured by HPLC with a Luna Pheny-Hexyl column (5 microm, 250 mm x 4.6 mm) employing UV detection at 210 nm using a mobile phase of potassium phosphate buffer (20mM, pH 3.0)-acetonitrile in a 45:55 (v/v) ratio. d-threo-1-phenyl-2-pentadecanoylamino-3-morpholino-1-propanol (PC15MP) was employed as an internal standard (IS). The lower limit of quantitation (LLOQ) was 0.3 microg/ml. The assay was linear over a concentration range of 0.3-10 microg/ml, with acceptable precision and accuracy. Assayed in plasma, the intra- and inter-day validation for all coefficients of variation (R.S.D.%) were found less than 15%. The method was applied to samples from athymic (nu/nu) mice treated with d-threo-PPMP by intraperitoneal injection. d-threo-PPMP levels of approximately 10-20 microg/ml ( approximately 20-40 microM) in plasma and approximately 45 microg/g in liver were obtained. The present method can be used to quantify d-threo-PPMP in mice for bioavailability and dose-response studies.

Assessing growth and response to therapy in murine tumor models.

Rodent models provide an important means of assessing antitumor activity vs toxicity for new cancer therapies. Tumors are often grown subcutaneously on the flank or back of animals, allowing accurate serial determination of tumor volume with calipers by measuring the tumors in three dimensions. The advantages of assessing tumor volume in subcutaneous tumors must be balanced against the potential artifacts induced by growth of tumor cells in subcutaneous tissue. Various orthotopic models have been developed. However, they are more labor-intensive and generally do not allow accurate assessment of tumor growth and/or response unless investigators have access to small animal cross-sectional imaging. Use of small-animal magnetic resonance imaging (MRI) allows one to assess the growth and response of intracavitary tumors, but the cost and labor-intensive nature of MRI limits its use in drug testing. Another approach to intracavitary solid tumor models is the intravenous injection of tumor cells, which can produce lung, liver, or bone metastases (depending on the cell line used), whereas direct injection of tumor cells into the femur or tibia of mice can cause local growth in bone. Progression of both lung metastases and bone lesions can be assessed by small-animal analog X-ray techniques that are more easily available and less labor-intensive to use, and are proving useful for selected therapeutic and biological studies.