Molecular Cancer Therapeutics最新文献

Recurrent high-grade serous ovarian carcinoma (HGSOC) and endometrial cancer (EC) remain major clinical challenges with limited effective treatment options. DHX9, a DNA/RNA helicase essential for genomic stability, has not yet been explored as a therapeutic target in gynecologic cancers. Here, we show that a selective DHX9 inhibitor (DHX9i) suppresses proliferation in a subset of HGSOC and EC cell lines by inducing DNA damage, chromosomal instability, and mitotic failure. This effect was independent of microsatellite instability status and prior resistance to platinum or PARP inhibitors. Genomic analysis indicated that DHX9i resistance was unlikely to be driven by single-gene mutations but was instead associated with copy-number alterations in mitotic spindle and microtubule-regulating genes in both HGSOC and EC. Transcriptomic profiling further revealed consistent alteration of microtubule- and spindle-associated pathways in DHX9i-resistant models following DHX9i treatment. Mechanistically, DHX9i induced mitotic defects in DHX9i-sensitive models, while resistant lines maintained mitotic integrity. Given the convergence of resistance-associated features on microtubule-related pathways, we combined DHX9i with the microtubule-stabilizing agent paclitaxel to enhance mitotic stress. This combination triggered mitotic disruption and enhanced cytotoxicity in DHX9i-resistant cells. In vivo, the combination led to sustained tumor regression and prolonged survival in both DHX9i-sensitive and -resistant models without notable toxicity. Overall, our findings define genomic, transcriptomic, and phenotypic characteristics associated with differential response to DHX9i and support clinical evaluation of DHX9i-paclitaxel combination as a therapeutic strategy in recurrent gynecologic cancers.

Diffuse intrinsic pontine glioma (DIPG) is a lethal pediatric brain tumor with limited therapeutic progress due to its infiltrative brainstem location, blood-brain barrier (BBB), and resistance to systemic agents. We present a novel strategy for targeted central nervous system (CNS) delivery of ATSP-7041, a stapled peptide dual inhibitor of human double minute 2 (HDM2) and X (HDMX), using the minimally invasive nasal depot (MIND) technique. In p53-wild-type, PPM1D-mutant DIPG neurospheres (BT869), ATSP-7041 exhibited ∼125-fold greater antitumor activity than the HDM2-selective antagonist RG7388, consistent with elevated HDMX expression. MIND delivery in mice achieved sustained ATSP-7041 distribution across brain regions, including the pons, with peak levels at 72 hours and persistence for up to 14 days. In a patient-derived orthotopic xenograft model of DIPG, a single MIND-administered ATSP-7041 depot reduced tumor burden and prolonged survival compared with controls. This feasibility study provides proof of concept for on-target p53 reactivation in DIPG using a BBB-penetrant dual HDM2/HDMX inhibitor delivered by the MIND platform. The findings support a translational path for ALRN-6924, the clinical analogue of ATSP-7041, in DIPG and potentially other brain tumors that retain wild-type p53 but remain incurable because of drug resistance and restricted CNS access.

Limited targeted agents are approved for pediatric sarcomas. Tyrosine kinase (TK) inhibitors have shown clinical efficacy in some, but not all, young sarcoma patients. A major obstacle preventing further advances and clinical implementation is the lack of predictive response biomarkers to guide TK-targeted treatments. TK-activating fusions or mutations are rare in these patients. RNA overexpression of TKs is a frequent feature. The unresolved question is when upregulated TK expression is associated with kinase activation and signaling dependence. We explored the TK molecular landscape of 107 sarcoma patients from the ZERO Childhood Cancer precision medicine program (ZERO) using whole genomic and transcriptomic sequencing. Phosphoproteomic analyses of tyrosine phosphorylation (pY) and functional in vitro and in vivo assays were performed in cell lines and patient-derived xenografts (PDXs). Our analysis shows that although novel genomic driver lesions are rare, when present they are therapeutically actionable as exemplified by a novel LSM1-FGFR1 fusion identified in an osteosarcoma patient. We further show that in certain contexts, TK RNA expression can indicate TK pathway activity and predict TK-inhibitor sensitivity. We highlight the utility of FGFR-inhibitors in PAX3-FOXO1 fusion-positive rhabdomyosarcomas (FP-RMS) characterized by high FGFR4 and FGF8 RNA expression levels, and FGFR4 activation (FGFR4_pY). We demonstrate marked tumor growth inhibition in all FP-RMS PDXs treated with single agent FGF401 (FGFR4-specific inhibitor) and single agent lenvatinib (multi-kinase FGFR-inhibitor), and report a clinical response to lenvatinib in a relapsed metastatic FP-RMS patient. Altogether, we identified new sarcoma patients who may benefit from FGFR-inhibitors, most notably FP-rhabdomyosarcoma via FGFR4/FGF8 co-expression.

This study tested the hypothesis that tumor cells can evade apoptosis following BH3 mimetic treatment by utilizing alternative Bim binding partners. Levels of Bim heterodimers with Mcl-1, Bcl-2 and Bcl-xL were measured in multiple hematologic cell line xenograft models (AMO-1, MV4-11, and RPMI-8226) following single-dose S63845 or venetoclax; Bak-Bax heterodimer and cleaved caspase-3 (cCasp3) levels were measured to demonstrate mitochondrial apoptosis. Anti-tumor efficacies of these agents were measured in vivo in mice bearing AMO-1 or MV4-11 xenografts and in vitro in patient-derived lymphoblastoid-like cells. Mechanism of combination activity of the CDC-like kinase (CLK) inhibitor cirtuvivint with venetoclax was determined in MV4-11 and KG-1a xenografts. S63845 decreased Mcl-1-Bim levels in AMO-1 and MV4-11 tumors by ~90% while unexpectedly decreasing Bcl-2-Bim and increasing Bcl-xL-Bim levels. Venetoclax decreased Bcl-2-Bim levels while increasing Mcl-1-Bim and Bcl-xL-Bim levels in MV4-11 tumors. The S63845+venetoclax combination decreased Mcl-1-Bim levels and demonstrated greater cell killing activity and pharmacodynamic effects than either single agent in multiple models including patient-derived lymphoblastoid-like cells. Cirtuvivint decreased Mcl-1 and Bim levels, combining with venetoclax to induce significantly greater Bak-Bax and cCasp3 responses than either single agent and induced regression of MV4-11 xenograft tumors. Our results elucidate quantitative pharmacodynamics of S63845, venetoclax, and cirtuvivint, an agent that is currently being evaluated with venetoclax to treat AML (NCT06484062). Compensatory increases in off-target Bim heterodimer levels in response to either S63845 or venetoclax offer a possible mechanism of clinical drug resistance.

Prostate cancer remains a major global health burden, with limited options and poor prognosis in advanced stages. To extend survival and improve quality of life for patients, targeted therapies have become an emerging treatment modality. Antibody-drug conjugates (ADCs) have shown huge clinical success but only limited therapeutic effects in prostate cancer since their large size limits tumor penetration. Small-molecule drug conjugates (SMDCs), consisting of a small molecule as binding moiety and a cytotoxic drug, offer advantages due to their smaller size, but their short plasma half-life and poor efficacy hampered their clinical breakthrough so far. Fc-grafted SMDCs (Fc-SMDCs) combine a small-molecule drug conjugate with the half-life extending Fc fragment of an antibody. So far, the Fc fragments have been attached directly to the Small-molecule drug complex making an enzymatic cleavable linker for payload release an indispensable prerequisite. We report a first-in-class Fc-SMDC targeting PSMA and carrying α-amanitin with a non-cleavable linker. The payload is conjugated directly to the Fc region via an engineered cysteine, to separate it from the targeting moiety. This approach enables in contrast to conventional Fc-SMDCs the use of non-cleavable linkers for minimal premature drug release, increased plasma stability and low systemic toxicity. Due to the non-cleavable linker, our conjugate showed a high tolerability and an extended half-life resulting in prolonged tumor exposure and an excellent anti-tumor efficacy in xenograft models. Together with the favorable tolerability in non-human primates, these findings highlight the potential as a next-generation treatment for prostate cancer.

V-domain immunoglobulin suppressor of T cell activation (VISTA) is a negative immune checkpoint and an emerging target for cancer immunotherapy, yet its broad expression on myeloid cells and T cells has complicated therapeutic antibody development. Here, we report two monoclonal antibodies (mAbs), Vs22 and Mu61, which were engineered from a common parental antibody and are cross-reactive with both human VISTA (hVISTA) and mouse VISTA (mVISTA). Vs22 demonstrates anti-tumor efficacy in the CT26 syngeneic model, whereas Mu61 is ineffective despite having a slightly higher affinity for mVISTA than Vs22. While both mAbs block VISTA-ligand interactions and deplete VISTA⁺ tumor-infiltrating immune cells via NK cytotoxicity, they differed in several aspects: they recognize similar but non-identical epitopes; only Vs22 enhances cytokine production by CD8⁺ T cells; and Vs22 exhibits a better pharmacokinetic (PK) profile and greater VISTA endocytosis. This multifaceted profile likely underlies Vs22's anti-tumor efficacy, in contrast to the inactive Mu61. Mechanistic studies revealed Vs22's anti-tumor activity requires coordinated fragment antigen-binding (Fab)-mediated VISTA blockade and fragment crystallizable (Fc) effector function and Vs22 treatment leads to durable, tumor-specific immune memory. Notably, combining Vs22 with TABBY106, an agonistic anti-4-1BB antibody, produced synergistic anti-tumor effects across CT26, MC38, and EMT6 models, substantially outperforming monotherapy. Collectively, we identify Vs22 as a cross-species anti-VISTA mAb that achieves effective tumor control by simultaneously blocking VISTA signaling and engaging strong Fc-mediated cytotoxicity. The synergy between Vs22 and 4-1BB-stimulation highlights a promising combination strategy to enhance anti-tumor immunity and supports the clinical translation of VISTA-targeting therapeutics.

Tumor-targeting antibodies, antibody-drug conjugates, and radionuclide antibody conjugates are established therapeutic tools in clinical use. Beyond, bispecific T-cell engaging antibodies (TCEs) and chimeric antigen receptor (CAR) T-cells are becoming clinical standard-of-care in hemato-oncology and in some solid tissue neoplasia. To allow for on-off switching and targeting of multiple antigens, CAR T-cells designed to recognize tumor-bound adaptor molecules (adaptor-CAR T-cells) are now being investigated in clinical trials. We hypothesized that, like adaptor-CAR T-cells, a bispecific TCE, recognizing CD3ε on T-cells and fluorescein on tumor-bound adaptors, would be able to direct T-cells against target cells, potentially enabling multi-plexing. We here show that a newly generated single chain Fv-based anti-CD3 x anti-FITC construct (AdFITC-TCE) activates T-cells towards acute myeloid leukemia. Recognition of multiple targets through binding to fluoresceinated antibody constructs against CD33 and CD117 enables efficient tumor cell lysis in vitro. Moreover, we demonstrate that AdFITC-TCE plus fluoresceinated adaptors and T-cells inhibit acute myeloid leukemia cell growth in NSG mice in vivo with similar efficacy as AdFITC-CAR T-cells. Together, this data suggests that AdFITC-TCE, in combination with any given fluoresceinated binder, might be a versatile tool to activate T-cells, leading to respective target cell lysis.

Small cell lung cancer (SCLC) is characterized by early metastasis, intrinsic chemoradiation resistance and tumor recurrence. Besides the lack of potentially targetable oncogenic drivers, therapeutic advancements are also hindered by the scarcity of surgically resected tissue specimens ideal for profiling studies. We used patient-derived xenografts (PDXs) to model SCLC chemoradiation resistance and identified chemoradiation resistance candidate genes using RNA sequencing. Additionally, we used human SCLC cell lines to confirm our in vivo results and delineate the underlying mechanism. Transcriptome profiling showed that the Traf2- and Nck-interacting kinase (TNIK) gene was consistently upregulated in an array of SCLC PDXs exposed to chemoradiation compared to monotherapy, which is consistent with previous observation of TNIK amplification in human samples. Genetic depletion (p<0.01) or pharmacological inhibition (p<0.0001) of TNIK reduced in vitro clonogenic survival of TNIKhigh SCLC cells and promoted sensitivity to chemoradiation. In vivo, pharmacological inhibition of TNIK enhanced chemoradiation sensitivity (p<0.0001) of H446 cell line-derived xenograft (CDX) in NOD-SCID mice. Furthermore, pharmacological inhibition of TNIK in vivo demonstrated sensitivity (p<0.0001) to chemoradiotherapy in LX33 PDX. These results indicate that TNIK plays a role in conferring resistance to chemoradiation in SCLC cell lines and in vivo in SCLC CDX and PDX models. Delineating the mechanism behind radiosensitization, suggested that TNIK inhibition may impair the DNA damage response in irradiated cells. Collectively, these findings suggest that TNIK may be a promising therapeutic target in limited-stage (LS) SCLC and support further investigation of TNIK inhibition in combination with standard chemoradiotherapy.

KRAS is a high-value therapeutic target for the treatment of cancer. Two covalent inhibitors, sotorasib and adagrasib, which target a specific codon 12 mutation (G12C), had received accelerated approvals for clinical use. Studies of these inhibitors ushered in the development of new inhibitors such as MRTX1133 that had entered clinical trials as a KRAS (G12D)-selective, non-covalent inhibitor. However, the subsequent failure of sotorasib as monotherapy and the recent termination of an early-phase clinical trial for MRTX1133 indicate that developing clinically effective allele-specific KRAS inhibitors remains a challenge, and that there is a need for further evaluation of KRAS inhibition mechanisms. Here, we show that the KRAS (G12D)-selective MRTX1133 also binds to G12C mutant KRAS with high affinity and suppresses nucleotide exchange and MAPK signaling in cancer cell lines harboring KRAS (G12C). However, its effect on the proliferation of KRAS (G12C) cancer cells is context-dependent; MRTX1133 robustly inhibits the proliferation of the pancreatic cancer cell line MIA PaCa-2 as well as the tumor growth of MIA PaCa-2 mouse xenografts but it has minimal effect in lung and colorectal cancer cells. This appears to be due to a lack of effect on downstream KRAS effectors such as the ribosomal protein S6, highlighting the need for strategies that take into account potential context-dependent processes. Together with other recent reports on high-affinity binding of MRTX1133 to other non-G12D KRAS mutants, our findings further reveal the usefulness of MRTX1133 as a chemical probe that continues to provide novel insights on KRAS biology and inhibition mechanisms.

Uterine serous carcinoma (USC) is an aggressive p53-mutated endometrial carcinoma that exhibits gene mutations in homologous recombination (HR) pathways, similar to high-grade serous ovarian carcinoma (HGSOC). However, the therapeutic effect of PARP inhibitors on USC is limited. This study investigated cyclin-dependent kinase 12 (CDK12), a transcriptional regulator of HR genes, and evaluated the efficacy of a novel CDK12 inhibitor, CTX-439, combined with a PARP inhibitor, olaparib, in patient-derived xenograft (PDX) models of USC. We evaluated the homologous recombination deficiency (HRD) scores, genetic alterations, and HR-related gene abnormalities, including CDK12 in USC, other histopathological types of uterine endometrial carcinoma, and HGSOC using the Cancer Genome Atlas dataset. We also assessed CDK12 function and CTX-439 efficacy in USC utilizing USC cell lines and PDX models. USC exhibited a higher HRD score than other histological subtypes of uterine endometrial carcinoma but lower than HGSOC. CDK12 amplification occurred more frequently in USC than in HGSOC but was not associated with HRD scores. Tumors with CDK12 amplification demonstrated high CDK12 expression, which correlated with poor prognosis in USC. The CDK12 inhibitor CTX-439 suppressed HR-related gene expression, including BRCA1 and BRCA2, induced apoptosis and DNA damage, and inhibited tumor growth in USC PDX models with high CDK12 expression. Furthermore, CDK12 inhibition enhanced tumor sensitivity to the PARP inhibitor, olaparib in USC PDX models. This study indicates that CDK12 is a potential therapeutic target for enhancing the antitumor effects of PARP inhibitors in patients with USC.