Human epidermal growth factor receptor 2 (HER2) is overexpressed in 15–20

Background/Objectives: Human papillomavirus (HPV) oncoproteins early (E)6 and E7 cause upregulation of the IL-6 and IL-23 cytokines in HPV16+ cancers, contributing to tumor progression through enhanced tumor cell proliferation and suppression of the tumor specific adaptive CD8 T-cell response. The IL-6 and IL-23 receptors signal through signal transducer and activator of transcription 3 (STAT3) in the tumor microenvironment. Methods: To better understand how HPV-induced STAT3 signaling contributes to tumor progression and explore its therapeutic potential, we used the platinum (IV) compound CPA-7, a specific STAT3 inhibitor. CPA-7 was tested in vitro for its ability to inhibit STAT3 signaling, alter proliferation, and cause cell death in HPV16+ C3.43 tumor cells. In vivo, CPA-7 was tested for its ability to affect the HPV specific T-cell response, tumor growth, and survival in C3.43 tumor bearing mice. Results: In vitro, CPA-7 inhibited STAT3 signaling, reduced proliferation, and caused significant cell death to HPV16+ C3.43 cells. In vivo, CPA-7 eradicated early-stage HPV16+ tumors, while therapeutic treatment of late-stage tumors led to a systemically increased presence of tumor-specific CD8 T-cells and halted tumor progression. Conclusions: These results suggest that targeting STAT3 signaling downregulates tumor cell proliferation and induces tumor cell death. In addition, targeting STAT3 increases the HPV-specific anti-tumor adaptive immune response. Combined, this results in significantly reduced late-stage HPV16+ tumor progression.

An investigation of the Hawaiian marine-derived fungus Fusarium sp. strain FM701 led to the isolation of two new pyridinium-containing fusaric acid dimers (1, 2), fusaric acid (3), and two known fusaric acid derivatives (4, 5), beauvericin (6), beauvericin J (7), and desferricrocin (8). Structures of 1 and 2 were elucidated by NMR spectroscopy, GIAO NMR calculations, HRESIMS, and electronic circular dichroism analyses. Genome mining revealed putative biosynthetic gene clusters for fusaric acid, beauvericin, and desferricrocin. Chemical synthesis of 9,10-dehydrofusaric acid (4) and racemic fusarinolic acid (5), combined with feeding experiments, supported their plausible biosynthetic relationship and potential roles as biosynthetic building blocks of dimeric metabolites 1 and 2. Compounds 1, 2, 6, and 7 exhibited potent antibacterial activity against Gram-positive bacteria, and all compounds (1-8) showed 2- to 4-fold enhanced activity when combined with a subinhibitory concentration of chloramphenicol. Beauvericin (6) also displayed strong antiproliferative activity against human breast (MCF-7) and prostate (DU145) cancer cell lines, with low micromolar IC50 values. Together, these findings expand the chemical diversity of fusaric acid metabolites and the biological potential of marine fungal metabolites.

Pharmacological targeting of Signal Transducer and Activator of Transcription 3 (STAT3) in cancer has demonstrable antitumor efficacy. However, suitably potent, efficacious, and safe STAT3 inhibitors are scarce, and only a handful have entered clinical trials, limiting our knowledge of the extent of clinical benefit. Outcomes of recently completed trials in advanced cancers range from improved overall survival and complete responses in a cohort of patients with phosphotyrosine STAT3 positivity to partial responses and progressive disease in unselected patients. Advancements in oligonucleotide technologies and the integration of E3 ligase-specific proteolysis-targeting chimeras and molecular glue protein degrader strategies are accelerating the transition of STAT3 inhibitors into clinical testing. This review examines recent STAT3-targeted modalities and their preclinical and clinical activities. It concludes by underscoring the value of biomarker-informed approaches to optimize patient outcomes, combination therapies to improve clinical benefits, and artificial intelligence/machine learning tools to accelerate development.

Abstract Signal transducer and activator of transcription 3 (STAT3) is a promising anti-cancer therapeutic target that promotes tumor development and progression. To study the STAT3-specific mechanisms underpinning tumor formation and that underlie the responses to its targeting, we used the validated mutant KrasG12D (KC) mice that under high-fat diet (HFD) has a high pancreatic adenocarcinoma (PDAC) incidence and progression, human cancer-associated fibroblasts (CAFs), PDAC and triple-negative breast cancer (TNBC) cells and xenograft models and interrogated STAT3 activity with two small molecule inhibitors, H182 and H279. Human CAFs, PDAC and TNBC cells harboring aberrantly-active STAT3 responded to growth factor and cytokine stimulation by further enhancing phospho-tyrosine-STAT3 (pYSTAT3) levels. Likewise, upon feeding KC mice the HFD, pYSTAT3 was strongly increased in cells that tracked along a path of altered phenotype, including acinar-ductal-metaplasia (ADM) elements, neoplastic ducts, stromal and immune cells, but was not present in normal acinar cells, in parallel with the development of pancreatic intraepithelial neoplasia (PanIN) lesions. To define the contexts of the pYSTAT3 and the phenotype changes, we probed the cells and mouse models with the inhibitors. The pYSTAT3 levels in the cells were suppressed early by H182 and H279 treatment. In PDAC cells, prolonged treatments with H182 severely shifted the secretome, including decreased IL-6-stimulated production of IL-8, SERPINE1, CXCL1, CXCL12, CCL2 and MIF, repressed the expression of genes involved in immune evasion, angiogenesis, cell proliferation, migration, oxidative stress and tumor progression, and upregulated tumor suppressor genes. In PDAC or TNBC cells, similar prolonged treatments with H182 or H279 also suppressed the expression of anti-apoptotic Mcl-1, Bcl-xL and c-Myc, pro-invasive matrix metalloproteinase 9, and the epithelial-mesenchymal transition proteins, SNAIL, Twist, Snug and ZEB, while inducing E-cadherin and pro-apoptotic Bax, Bad, PUMA and BIM. Treatments of PDAC and TNBC cells with the inhibitors also led to DNA damage, γH2AX, ATM and Chk2 induction, mitochondrial oxygen consumption rate impairment, cell cycle arrest at the G2/M phase, decreased viability, migration and invasiveness in vitro, and apoptosis. H182 treatment prevented acinar cell de-differentiation into ADM/PanINs, in parallel with decreased pro-fibroinflammatory gene expression in the pancreas, such as CXCL12, CCL2, and CCL5 in HFD-fed KC mice, and inhibited growth of PDAC subcutaneous xenografts in mice. Together, the findings support a hyperactivated STAT3-pro-fibroinflammatory cytokines and chemokines axis in diverse cell types within tumors that is critical in tumor initiation and progression. Inhibiting STAT3 functions may be a preventative and therapeutic approach against cancer. Citation Format: Rasaq Akinsola, Monday Ogaba Ogese, Lihong Huo, Yue Chen, Francisco Lopez-Tapia, Richard T. Waldron, Aurelia Lugea, Stephen J. Pandol, James Turkson. Small molecules inhibited dysregulated STAT3-proinflammatory axis and induced antitumor responses in pancreatic and breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4563.

Pancreatic adenocarcinoma (PDAC) is a major healthcare challenge. Currently, there are no good treatments for PDAC, and patient survival is dismal. In vitro and in vivo models to study PDAC pathogenesis have shed some light on the molecular and cellular landscape of the disease, including the prevalence of altered signal transducer and activator of transcription 3 (STAT3) functions. While constitutively-active STAT3 is implicated in PDAC progression, its functional role in driving PDAC development is not fully understood. Using human PDAC (hPDAC) cell lines, hPDAC-derived cancer-associated fibroblasts (hCAFs), and high-fat diet (HFD)-fed mutant KrasG12D (KC) mice, we interrogated aberrantly-active STAT3 and its cell-type specificity to delineate STAT3’s role in PDAC development and therapeutic response. Human PDAC cell lines (AsPC-1, Mia-PaCa-2, and PANC-1) and hCAFs harbor constitutively-active STAT3, and their stimulation with IL-6, EGF or PDGF further enhanced the phospho-tyrosine-STAT3 (pYSTAT3) levels. In KC mice, feeding a HFD led to constitutive pYSTAT3 induction in the pancreas in parallel with the development of precancerous pancreatic intraepithelial neoplasia (PanIN) lesions. Induction of pYSTAT3 occurred across diverse cell types, including acinar-ductal-metaplasia (ADM) elements, neoplastic ducts, stromal and immune cells, but not in acinar cells. Treatment with the STAT3 inhibitor, H182, blocked the pYSTAT3 levels in the hCAFs and hPDAC cells in vitro. Significant profile changes for IL-6-stimulated cytokine and chemokine secretion were also observed, including decreased IL-8, SERPINE1, CXCL1, CXCL12, CCL2 and MIF secretion. Mia-PaCa-2 cells exposed to H182 for 48 h showed a repression of genes involved in immune evasion (HLA-E, AGRN), angiogenesis (LOXL2), cell proliferation and migration (IL-8, UBC, JAG1), oxidative stress (NQO1, SRXN1, TXNRD1) and tumor progression (BCL10, HMOX1, HMGA1, SERPINE1), in parallel with the upregulation of TP53 and NBPF1 tumor suppressor genes. H182 treatment of the hPDAC lines further repressed mitochondrial oxygen consumption rate and viable cell numbers and induced apoptosis. Administration of H182 to HFD-fed KC mice prevented acinar cell differentiation into ADM/PanINs and suppressed pro-fibroinflammatory genes in the pancreas, including CXCL12, CCL2 and CCL5, while inhibiting the growth of subcutaneous hPDAC xenografts in mice. The decreased proinflammatory cytokine and chemokine profiles across diverse cell types, associated with the enrichment of acinar cells in the pancreas of KC mice in response to STAT3 inhibition underscores declining STAT3-dependent pro-tumorigenic mechanisms that are orchestrated through a HFD-induced chronic inflammation. The translational significance is that the blockade of aberrant STAT3 functions suppresses growth of PanINs and cancer cells in PDAC. Monday O. Ogese, Lihong Huo, Yue Chen, Benjamin Jackel, Francisco Lopez-Tapia, Richard T. Waldron, Aurelia Lugea, Stephen J. Pandol, James Turkson. STAT3 Orchestrates common and divergent mechanisms in different cell types to promote pancreatic cancer development and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1741.

Aberrantly-active signal transducer and activator of transcription (Stat)3 has a causal role in many human cancers and represents a validated anticancer drug target, though it has posed significant challenge to drug development. A new small molecule, JKB887, was identified through library screening and is predicted to interact with Lys591, Arg609 and Pro63 in the phospho-tyrosine (pTyr)-binding pocket of the Stat3 SH2 domain. JKB887 inhibited Stat3 DNA-binding activity in vitro in a time-dependent manner, with IC50 of 2.2-4.5 mu M at 30-60-min incubation. It directly disrupted both the Stat3 binding to the cognate, high-affinity pTyr (pY) peptide, GpYLPQTV-NH2 in fluorescent polarization assay with IC50 of 3.5-5.5 mu M at 60-90-min incubation, and to the IL-6 receptor/gp130 or Src in treated malignant cells. Treatment with JKB887 selectively blocked constitutive Stat3 phosphorylation, nuclear translocation and transcriptional activity, and Stat3-regulated gene expression, and decreased viable cell numbers, cell growth, colony formation, migration, and survival in human or mouse tumor cells. By contrast, JKB887 had minimal effects on Stat1, pErk1/2MAPK, pShc, pJAK2, or pSrc induction, or on cells that do not harbor aberrantly-active Stat3. Additionally, JKB887 inhibited growth of human breast cancer xenografts in mice. JKB887 is a Stat3-selective inhibitor with demonstrable antitumor effects against Stat3-dependent human cancers.

Abstract The incidence and death rates for pancreatic adenocarcinoma in the US have been increasing by about 1% per year and the death rate has increased by approximately 0.2% yearly. The five-year survival rate has remained below 10% for many years. With surgery, radiation, and chemotherapy being the main treatment options to extend survival or for symptom relief, there is an urgent unmet need for effective new treatment options. Signal Transducer and Activator of Transcription (Stat) 3, one of the Stat family members, is aberrantly activated in human pancreatic and many other cancers. Aberrantly-active Stat3 promotes abnormal tumor-cell intrinsic and extrinsic mechanisms, including dysregulation of gene expression and mitochondria energy metabolism in the tumor cells, and suppression of immune cell functions in the tumor microenvironment. Stat3 is therefore an important target for therapeutic development. Herein we present two small molecules, H182 and H333, which are covalent inhibitors of Stat3 and that potently block Stat3 DNA-binding activity in vitro, with IC50 0.66-0.98 µM. H182 and its structural analog, H333 bind Stat3 via irreversible covalent interactions with key cysteine residues in the Stat3 DNA-binding domain to induce a time-dependent inhibition of Stat3 activity. Both compounds inhibit intracellular constitutive Stat3 tyrosine phosphorylation and induce loss of viable cells and apoptosis in vitro of human pancreatic Panc-1 and Mia-Paca2 cells. H333 is 13-fold more specific and H182 is 4-fold more specific against tumor cells over normal cells. Furthermore, MiaPaca-2 cells treated with H182 and analyzed by Seahorse showed dramatically decreased mitochondria respiration. Notably, xenograft models of MiaPaca2 treated with H182 or H333 via i.p. every other day for 27 days showed dramatic growth inhibition. Collectively, our results identify H182 and H333 as therapeutically-viable small molecules with unique irreversible mechanism of Stat3 inhibition which accounts for their strong antitumor effects against human pancreatic tumor xenografts. Citation Format: Yue Chen, Ning Zhai, Peibin Yue, Christine Brotherton-Pleiss, Wenzhen Fu, Kayo Nakamura, Weiliang Chen, Marcus Tius, Francisco Lopez-Tapia, James Turkson. Irreversible covalent azetidine-based small molecule inhibitors of Stat3 activity block growth of human pancreatic tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 663.

Unlike classical Signal transducer and activator of transcription (Stat) signaling, which is transient in non-transformed cells, the aberrant activation of the family member, Stat3, occurs in malignant transformation and is implicated in breast, ovarian and many other human cancers. Thus, Stat3 remains a validated and important target for the discovery of novel anticancer drugs. Despite this, the discovery and development of potent Stat3 small molecule inhibitors has proven to be a significant challenge, and no drug is available yet in the market. We have discovered novel Stat3 irreversible azetidine inhibitors with unprecedent submicromolar potency through systematic medicinal chemistry structure activity relationship (SAR). Mechanism of action of most potent azetidine inhibitors depend on whether they are salicylic acids or not, i.e., salicylic acids preferably bind irreversibly to Stat3 Cys426 site in the DNA-binding domain (DBD), and non-salicylic acids, e.g., current lead H182, bind to Stat3 Cys468 DBD site. As expected, the inhibition of Stat3 DNA-binding activity was time dependent, with IC50 in the range of 0.27-0.87 µM at one hour incubation with active Stat3. On the other hand, azetidine salicylic acids also bind to the SH2 domain, although reversibly and at much weaker affinity, as determined in fluorescent polarization (FP) assay, with IC50 of 10-16 µM at one hour incubation, while non-salicylic acids, e.g., lead H182, present no binding affinity up to 600 µM for the SH2 domain. Despite that H182 does not bind to SH2 domain, it still inhibits its phosphorylation. Though lead compound H182 presents significant mouse in vivo efficacy, mouse in vivo pharmacokinetics shows very low plasma AUC, which correlates with quite high mouse in vitro hepatocyte CLint of 138 µL/min/106 cells; however, human in vitro hepatocyte assay gives much better results and is in the middle stability range (CLint of 14.6 µL/min/106 cells). The in vivo PK in other species, e.g., rat, is being determined. H182 represents a plausible molecule for further development. Citation Format: Yue Chen, Ning Zhai, Yinsong Zhu, Peibin Yue, Nagendra Verma, Christine Brotherton-Pleiss, Wenzhen Fu, Kayo Nakamura, Weiliang Chen, Marcus Tius, Francisco J. Lopez-Tapia, James Turkson. Novel potent azetidine-based inhibitors bind irreversibly to Stat3 DNA-binding domain (DBD) and are efficacious against tumor growth in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 514.

Signal transducer and activator of transcription 3 (Stat3) is a latent transcription factor that contributes to tumor cell growth and survival in constitutively-active form in several types of human cancers, and hence, serves as a therapeutic target. The azetidine-based compound, H182 irreversibly binds to Stat3. In cell-free DNA-binding assay, H182 selectively inhibited Stat3 DNA-binding activity (IC50 0.38-0.66 μM) over Stat1 or Stat5 (IC50>15.8 μM) in vitro. In treated pancreatic cancer cells, H182 specifically blocked the association of Stat3 with gp130 and JAK2, and inhibited Stat3 tyrosine phosphorylation and DNA-binding activity. Coimmunoprecipitation and colocalization studies of hemagglutinin (HA)-tagged Stat3 and EGFP-tagged Stat3 expressed in prostate cancer cells showed that treatment with H182 blocked the HA-Stat3:EGFP-Stat3 interactions in intact cells. Immunofluorescence staining with laser-scanning confocal microscopy analysis for the intracellular localization of Stat3 showed treatment of H182 disrupted Stat3 nuclear accumulation and promoted the aggregation of Stat3 at the perinuclear region. H182 consequently suppressed Stat3-dependent transcriptional activity and the expression of Stat3 downstream genes, including Cyclin A, Bcl-2, Cyclin B1, and Mcl-1. Moreover, H182 significantly inhibited the colony survival, migration, and invasion in vitro of breast, pancreatic and prostate cancer cells harboring aberrant Stat3 activation. Significantly, in vivo administration of H182 in combination with radiation induced a strong antitumor response against mouse triple-negative breast cancer in syngeneic models and prolonged survival. Thus, our study provides a novel Stat3 inhibitor with significant antitumor activity against human tumors cancer harboring persistently active STAT3. Citation Format: Yue Chen, Peibin Yue, Wenzhen Fu, Weiliang Chen, Kathleen M. Kershaw, Stephen L. Shiao, Marcus A. Tius, Francisco Lopez-Tapia, James Turkson. Small molecule H182 suppresses Stat3 activation in tumor cells and combines with radiation therapy to block breast tumor growth in mouse syngeneic models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2782.

Supplementary table of the statistical analysis of the TUNEL staining

Supplementary text for publication

Supplementary Figure S1. Phase-contrast microscopy imaging of cellular morphology of tumor cells after treatment with 15α-MP; Supplementary Figure S2. Global phospho-protein expression in U251MG cells and the changes induced in response to treatment with 15α-MP; Supplementary Figure S3. Immunoprecipitation and immunoblotting analyses of estrogen receptor (ER) α and Stat3

PC3 and DU145 dose finding studies for STAT3 inhibitors

Correlation studies in AR high and AR low patient samples

Supplementary Methods, Figures 1-8, Table 1 from Constitutively Active Stat3 Enhances Neu-Mediated Migration and Metastasis in Mammary Tumors via Upregulation of Cten

Supplementary Table 1 from The High-Mobility Group A1a/Signal Transducer and Activator of Transcription-3 Axis: An Achilles Heel for Hematopoietic Malignancies?

Supplementary Figures S1-8. Fig. S1: EMSA analysis of Stat3 DNA-binding activity in vitro showing the effect of BP-1-102. Fig. S2: Effects of SH5-07, SH4-54 or BP-1-102 on Stat3 tyrosine and serine phosphorylation in tumor cells and on Stat3 DNA-binding activity in vitro. Fig. S3. Immunoblotting analysis for the effects of SH4-54 and SH5-07 on the induction of Stat3-independent signal transduction events. Fig. S4. Immunoblotting analysis for the effects of SH5-07 on EGF-induced phosphorylation of the EGF receptor and Stat3. Fig. S5. Nuclear magnetic resonance analysis of SH4-54 or Stat3 in solution alone or with N-Ethylmaleimide (NEM). Fig. S6. Immunoblotting analysis of the total Stat3 and phospho-TyrStat3 levels across diverse cell lines. Fig. S7. Transformation and migration studies in vitro of MDA-MB-231, U251MG or DU145 cells and the effects of SH5-07. Fig. S8. Body weights, blood cell counts, and the gross anatomical presentation of the organs of tumor-bearing mice and the effects of SH5-07 or SH4-54.

Cytokine-mediated JAK-STAT signaling is the key driver of growth, differentiation, apoptosis, and immune responses across multiple cell types, especially lymphocytes. A hallmark of malignant cells is their ability to subvert and highjack existing cellular components to create new and dysregulated signaling pathways not observed in normal counterparts. Thus, it is unsurprising that lymphoid malignancies exhibit profound dysregulation of JAK-STAT signaling through gain of positive signals as well as loss of negative signals. This review will focus on intracellular responses to cytokine signaling, mechanisms of dysregulation in lymphoid malignancies, therapeutic strategies to inhibit JAK-STAT signaling, progress toward translating these therapeutics to the clinic, and next steps needed to maximally target this key pathway.