Abstract The androgen receptor (AR) is a key therapeutic target in prostate cancer, being an important tumor driver in patients with metastatic hormone-sensitive prostate cancer (mHSPC), and AR alterations are a key mechanism of acquired resistance to androgen deprivation therapy (ADT) and androgen receptor pathway inhibitors (ARPIs) in those with metastatic castration resistant prostate cancer (mCRPC). JSB462 (Luxdegalutamide, formerly ARV-766) is an orally bioavailable proteolysis targeting chimera (PROTAC®) that induces a protein-protein interaction between AR and the Cereblon (CRBN) E3 substrate receptor, resulting in the ubiquitination of AR and its subsequent degradation via the proteasome. JSB462 is efficacious against wild type AR as well as clinically relevant AR ligand binding domain (LBD) mutants that confer resistance to ADT and ARPIs, including AR L702H, H875Y, and T878A mutations. AR degradation overcomes limitations of conventional AR antagonists that only inhibit AR activity and cannot compensate for the feedback loop leading to AR upregulation. JSB462 demonstrates potent AR degradation at sub-nanomolar concentrations in vitro and dose-dependent tumor growth inhibition in mouse xenograft models, including those resistant to enzalutamide and with high levels of AR. In addition to degrading the androgen receptor, JSB462 also exhibits direct antagonistic activity against AR signaling, inhibiting AR-driven transcriptional programs independent of receptor abundance. Beyond single agent activity, we have also explored biology-guided combination opportunities to maximize JSB462 efficacy. Abiraterone inhibits AR activity by targeting CYP17A1 and reducing synthesis of androgen receptor ligands, and combination with JSB462 leads to sustained AR pathway inhibition and improved in vivo efficacy. JSB462 treatment leads to sustained upregulation of PSMA in multiple prostate cancer cell lines, and pre-treatment of prostate tumor xenografts with JSB462 in combination with a sub-efficacious single dose of the PSMA-targeting radioligand therapy (RLT) Lutetium (177Lu) Vipivotide Tetraxetan (Pluvicto®) led to sustained tumor growth inhibition. In a phase I/II trial, JSB462 was well tolerated and showed encouraging antitumor activity in pretreated patients with mCRPC. Here, we show preclinical combination data of JSB462 with abiraterone and Pluvicto® that support further investigation of these regimens. Towards that end, two phase 2 trials of JSB462 in combination with abiraterone in patients with high-volume mHSPC (NCT06991556) as well as in combination with Pluvicto® in patients with mCRPC (NCT07047118) are ongoing. Citation Format: Stephane Ferretti, Daniel A. Guthy, Marco Taddio, Marc Hattenberger, Marion Dourdoigne, Ramona Stump, Sabina Ciaghi, Mylene Lanter, Alessandra Amadori, Laurent Laborde, Asif Khan, Rafael Caparica, James Warburton, Marta Cortes Cros. Preclinical characterization and evaluation of JSB462 (Luxdegalutamide), a novel AR degrader, and its combinations in prostate 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 4615.

Non-small cell lung cancer (NSCLC) patients with tumors harboring STK11 mutations are resistant to standard of care anti-PD-1/PD-L1 blockade. For this patient population there are no currently available tailored treatments, underlying the critical need to discover effective therapeutic strategies. In this study, we dissected the molecular mechanisms responsible for STK11-mediated resistance to immune checkpoint blockade (ICB) and identified CRTC2, a coactivator of the transcription factor cAMP response element-binding protein (CREB), as a key signaling node regulating Stk11-dependent cell-extrinsic functions. CRTC2 deletion remodeled the immune profiles of Stk11-KO tumors and resensitized them to anti-PD-1 treatment, comparably to Stk11-proficient tumors. Mechanistically, the abrogation of the binding between CRTC2 and CREB was sufficient to restore sensitivity to immunotherapy. These findings provide critical insights into the central role of CRTC2 in modulating response to ICB and identify the disruption of CRTC2-CREB interaction as a potential therapeutic approach for this patient population.

Antibody-drug conjugates (ADCs) are an established modality which allows for targeted delivery of a potent molecule, or payload, to a desired site of action. ADCs, wherein the payload is a targeted protein degrader is an emerging area in the field. Herein we describe our efforts of delivering a Bruton’s tyrosine kinase (BTK) bifunctional degrader 1 via a CD79b mAb where the degrader is linked at the ligase binding portion of the payload via a cleavable linker to the mAb. The resulting CD79b ADCs, 3 and 4, exhibit in vitro degradation and cytotoxicity comparable to 1 and ADC 3 can achieve more sustained in vivo degradation than iv administered 1 with markedly reduced systemic exposure of the payload.

A video describing PDX mice, minimal information, and why minimal information is needed in the PDX research field.

The Werner syndrome RecQ helicase WRN was identified as a synthetic lethal target in cancer cells with microsatellite instability (MSI) by several genetic screens(1-6). Despite advances in treatment with immune checkpoint inhibitors(7-10), there is an unmet need in the treatment of MSI cancers(11-14). Here we report the structural, biochemical, cellular and pharmacological characterization of the clinical-stage WRN helicase inhibitor HRO761, which was identified through an innovative hit-finding and lead-optimization strategy. HRO761 is a potent, selective, allosteric WRN inhibitor that binds at the interface of the D1 and D2 helicase domains, locking WRN in an inactive conformation. Pharmacological inhibition by HRO761 recapitulated the phenotype observed by WRN genetic suppression, leading to DNA damage and inhibition of tumour cell growth selectively in MSI cells in a p53-independent manner. Moreover, HRO761 led to WRN degradation in MSI cells but not in microsatellite-stable cells. Oral treatment with HRO761 resulted in dose-dependent in vivo DNA damage induction and tumour growth inhibition in MSI cell- and patient-derived xenograft models. These findings represent preclinical pharmacological validation of WRN as a therapeutic target in MSI cancers. A clinical trial with HRO761 (NCT05838768) is ongoing to assess the safety, tolerability and preliminary anti-tumour activity in patients with MSI colorectal cancer and other MSI solid tumours.

PDF - 92K, NVP-BYL719 does not inhibit mTOR and PIKKs involved in DNA damage-repair processes. A. TSC1 -/- MEFs cells were grown in a 96-well format and treated for 1 h with increased concentrations of RAD001 or NVP-BYL719 (from 0.5 nmol/L to 10 ?mol/L in 1 third dilution steps) and immediately fixed. S235/236P-RPS6 levels were measured and IC50 determined with the Excel module XLfit. Background (no primary Ab incubated); BL, Baseline. B: TSC1 -/- MEFs cells were treated with increasing concentrations of NVP-BYL719 as indicated or RAD001 at 500 nmol/L or an equivalent DMSO concentration for 30 minutes. Levels of S235/236P-RPS6 and total RPS6 in protein- normalized lysates were detected by Western blot analyzis using an activation-state specific antibody, followed by incubation with species- specific HRP-labeled secondary antibody and signal development by ECL. C: 24 h post seeding, A549 cells were treated at the same time with Actinomycin D (Act D) at a concentration of 5 ?mol/L (an agent used to induce DNA damage), and with increasing concentrations of NVP-BYL719 as indicated or with the vehicle control (DMSO) for 1 h. Levels of S15P-p53 and tubulin in protein-normalized lysates were detected by Western blot analysis using an activation-state specific antibody, followed by incubation with species- specific HRP-labeled secondary antibody and signal development by ECL. D: 24 h post seeding, U2OS cells were pre-treated for 1 h with increased concentrations of NVP-BYL719 or KU55933 a specific small molecular mass inhibitor of ATM (Supplementary reference 1) at a concentration of 10 ?mol/L or with the vehicle control (DMSO). The cells were then irradiated with 15 Gy and re-incubated at 37 degrees C for 1 h and then lysed. Levels of S1981P-ATM in protein- normalized lysates were detected by Western blot analysis using an activation-state specific antibody, followed by incubation with species- specific HRP-labeled secondary antibody and signal development by ECL.

Supplementary material and methods include the description for the bioanalytical method for HDM201 detection in plasma and tumor, the human and mouse gene expression analysis in vitro and in vivo, the live-cell quantification of cleaved-caspase activation, the western blot analysis, the immunohistochemistry, the splinkerette PCR for the amplification of transposon integration sites and the tumor sequencing, mapping of insertion sequences to the mouse genome and identification of common integration site, additional information on the shRNA screen and the tumor models and supplementary references. Supplementary figures include: • Fig S1: the SJSA-1 inhibition growth curves when treated with HDM201 at different doses and for different times and the data for MOLM-3. • Fig S2: the cumulative percentage of cleaved-caspase-3/7 positive cells over the time, the GI50 of HDM201, CGM097 or nutlin-3a on SJSA-1 cells and the cellular apoptosis, as judged by AUC of cleaved-caspase-3/7 positive cells, induced by these compounds. • Fig S3: the PK profile in plasma and tumor of HDM201 in SJSA-1 tumors-bearing rat after p.o. and i.v. treatment, the Bcl-xl mRNA levels in tumors after HDM201 treatment, representative images of SJSA-1 tumors stained with p53 and cleaved-caspase 3 antibodies after HDM201 treatment and the individual data for the efficacy experiment in SJSA-1 tumor-bearing rats. • Fig S4: the PD of HDM201 in PB tumor bearing nude mice after single dose administration. Supplementary tables include: • Table S1: Biochemical profile of HDM201. • Table S2: List of cell lines tested for their sensitivity to HDM201 (n=291) • Table S3: Contingency table indicating association between sensitivity to HDM201 and TP53 wild-type status. • Table S4: List of cell lines tested for their sensitivity to both MDM2 knock-down by shRNA and HDM201 (n=261) • Table S5: Contingency table indicating association between sensitivity to HDM201 and sensitivity to MDM2 shRNA. • Table S6: List of significant rescuer and sensitizer genes following both HDM201 treatment types • Table S7: Pharmacokinetic parameters for HDM201 after p.o. and i.v. dosing in rat. • Table S8: Summary of primary PK parameters for HDM201 daily regimen after single dose (Day 1) in patients. • Table S9: Summary of primary PK parameters for HDM201 daily regimen on Day 14 in patients. • Table S10: Summary of primary PK parameters for HDM201 q3w regimen after single dose in patients.

Median of the shRNAs and RSA values. File containing median counts and log fold changes of each gene from Supplementary Data File S1. According significance values of each gene as activator or sensitizer compared to DMSO control (see Methods) are included.

Description of additional methods and procedures used in the study. Also includes Supplementary References.

Supplementary Figures S1-S9 from Quantified Tumor T1 Is a Generic Early-Response Imaging Biomarker for Chemotherapy Reflecting Cell Viability

Selective single agents and combinations.

Data for characterization of triple combination targeting MDM2, MEK, and BCL-2/-XL.

Colorectal carcinoma (CRC) as well as other indications that have lost competence in mismatch repair and have a phenotype known as microsatellite instability (MSI), remain a significant unmet medical need. Large-scale functional genomics screens across cell line panels have identified the Werner Syndrome RecQ helicase (WRN) as being synthetic lethal with MSIhigh cancers. Thus, WRN inhibitors may offer a new therapeutic avenue in MSIhigh cancers. We report the preclinical characteristics of HRO761, a first-in-class, highly potent and selective inhibitor of WRN helicase, with optimized drug-like properties. We evaluated the pharmacokinetics and pharmacodynamics of HRO761 when administered orally once daily in MSIhigh and also assessed the efficacy as single agent across cell (CDX) and patient-derived (PDX) xenografts as well as in combination with irinotecan, a prodrug derivative of camptothecin which acts as topoisomerase I inhibitor. Daily oral administration of HRO761 was highly efficacious across the CDX and PDX models evaluated with a disease control rate of 70% across all indications. In the SW48 CDX model, tumor regression was sustained for 2 months at the highest dose followed by slow relapse. HRO761 also induced WRN degradation, activated the DNA damage response and induced p53 target genes in a dose dependent manner. In vitro combination with irinotecan deepened sensitivity to HRO761 with a more sustained response in MSIhigh CRC cell lines. Combining administration of HRO761 daily with irinotecan weekly was highly efficacious and beneficial over single agent in CDX and PDX models. In CDX models, the combination showed a robust benefit, translating into homogeneous, sustained regression leading to a dose-dependent tumor growth delay even after treatment discontinuation. Overall, we demonstrate that the novel, selective, first-in-class WRN inhibitor HRO761 is a promising therapeutic approach for the treatment of MSIhigh cancer patients either as single agent or in combination with irinotecan. Clinical development is currently ongoing to assess the safety, tolerability and preliminary anti-tumor activity in patients with MSIhigh colorectal cancer and other MSIhigh solid tumors [clinicaltrials.gov NCT05838768]. Citation Format: Stephane Ferretti, Isabel Jaco, Andrea Decker, Christelle Hemmerlin, Clemens Scheufler, Cornelia Quadt, Dario Sterker, Elena Gavioli, Eloisa Jimenez Nunez, Ernesta Dammassa, Fanny Schaeffer, Genevieve Albrecht, Giorgia Clementi, Hansjoerg Martus, Jacques Hamon, Juergen Hinrichs, Laurent Laborde, Marion Dourdoigne, Michele Moschetta, Ramona Stump, Rita Andraos-Rey, Sarah Welly, Stephanie Barbe, Vincent Romanet, Markus Reschke, Ruben De Kanter, Michael Jensen, Henrik Moebitz, Marta Cortes Cros. HRO761, a first-in-class, clinical stage WRN inhibitor with potent preclinical anti-tumor activity in MSIhigh models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B143.

List of individual shRNA scores. File containing raw data of individual shRNAs quantified by barcode sequencing of DMSO- and HDM201- treated samples. Log fold changes of individual shRNAs compared to plasmid library and of HDM201-treated samples compared to DMSO-control are also listed.

Legend for Supplementary Tables S1-S6 and Supplementary Figures S1-S15.

Insertional results from Arf-/- PB in vivo resistance screens. A and C, Tables listing all sequenced samples with their model number (i.e. X25272), the transplanted fragment number (i.e. P0M1-P1M5-P2M19, P for passage, and M for Mouse), tumor status (DR=drug resistant, or veh=vehicle treated) and treatment schedule (A) QD for daily or (C) 2QW for biweekly. Total number of reads and tumor pathology are labeled for each sample. Insertional landscapes are displayed on the right part of the table where the averaged normalized diversity sequencing counts are indicated for each Common insertion site gene (gCIS) and each tumor. B and D, List of the genes found differentially enriched for PB insertions in HDM201 resistant tumors compared to untreated tumors (B) continuous daily treatment or (D) biweekly intermittent treatment. The data in D were extracted from previous report (28) for intermittent 100 mg/kg biweekly dosing schedule, and reanalyzed with only 6 tumor models used out of 16 in previous report. Fold change, p-value and FDR were calculated for each gene in comparative analyses of untreated tumor samples vs. resistant tumor samples. PercentSample indicated the percentage of resistant tumors with insertion in that gene. The predicted function GOF (gain of function), LOF (loss of function) or uncertain is also indicated.

From images to synergies (S1); Reproducibility of data from two screens (S2); Single agent responses and selectivity (S3); Screen-wide comparison of Caspase 3/7 activation and growth inhibition (S4); Heatmaps of growth inhibition and Capase 3/7 activation, and examples of broadly synergistic combinations targeting RAS/MAPK and/or PI3K/AKT pathways (S5); Combinations targeting RAS/MAPK and PI3K/AKT pathways at different nodes show similar efficacies (S6); Combinations involving RTKs (S7); Heatmaps of growth inhibition and Capase 3/7 activation, and examples of combinations targeting RAS/MAPK or PI3K/AKT pathways and other cellular processes (S8); Synergies of triple combination increase with synergies of underlying drug pairs (S9); Heatmap of synergies, growth inhibition, and Caspase 3/7 activation for triple combinations after hierarchical clustering (S10); Triple combinations targeting RAS/MAPK and PI3K/AKT pathways (S11); Triple combinations targeting RAS/MAPK and/or PI3K/AKT pathways and other cellular processes (S12); Combination targeting MDM2 and MEK in p53 wild-type models (S13); Sequential treatment of p53 wild-type lines with triple combination targeting MDM2, MEK, and BCL-2/-XL (S14); High order combinations to kill 'robust' cell lines (S15).

Supplementary Data from Results from a First-in-Human Phase I Study of Siremadlin (HDM201) in Patients with Advanced Wild-Type TP53 Solid Tumors and Acute Leukemia

PDF - 71K, Rat1-myr-p110alpha (blue), beta (green) or delta (red) cells were treated with increasing concentrations of NVP-BYL719 for 30 minutes. Levels of S473P-Akt in cell extracts were quantified by Reverse Phase Protein Array as described in (18) and plotted as percentage of untreated control cells. The graph illustrates n=3 independent experiments. IC50s (plus/minus) SD and IC80s (plus/minus) SD of n=3 independent experiments are reported..

Summarized results for high-order combinations in DLD-1, RKO, HT-29, and LS-180 cell lines.