Significant Antitumor Activity Research Articles

Phase I safety and preliminary efficacy of PM1009, a bispecific antibody targeting TIGIT and PVRIG, in patients with advanced solid tumors.

e14695 Background: PM1009 is an anti-TIGIT x PVRIG bispecific antibody containing a fully human anti-TIGIT IgG1 fused with a fully human anti-PVRIG scFv at the C terminus. PM1009 can potently block the TIGIT/CD155/CD112 and PVRIG/CD112 signaling pathways, and supports the depletion of TIGIT-positive Treg cells in the tumor microenvironment through FcγR engagement. This leads to the enhancement of T cell and NK cell activity towards the killing of tumor cells. PM1009 showed robust in vitro and in vivo efficacy with good safety in preclinical studies. Methods: This is the first-in-human study of PM1009, which includes a dose escalation stage (accelerated titration & 3+3 design) followed by dose expansion. In the dose escalation stage, PM1009 was administered as flat doses of 120, 300, 600 and 1200 mg for DLT evaluation after 3 weeks followed by administration Q2W. Primary endpoints were safety and tolerability, and the secondary endpoints were PK, ORR and DCR (per RECIST 1.1). Results: As of February 1, 2024, a total of 12 patients were enrolled for dose escalation and received at least one dose of PM1009, with 3 patients in each of the 120, 300, 600 and 1200 mg dose-levels. Median number of prior therapies was 5 lines (range 1- 9). No DLTs were observed up to 1200 mg. Any-grade TRAEs occurred in 11 patients (91.7%), and ≥ Grade 3 TRAEs occurred in 2 patients (16.7%). Any-Grade irAEs occurred in 7 patients (58.3%), and ≥ Grade 3 irAEs occurred in 1 patient (8.3%). Treatment interruption due to TRAE occurred in 2 patients (16.7%), with infusion related reaction (the main symptom was nausea, and the single infusion was eventually completed), and neutrophil count decrease respectively. Treatment discontinuation due to TRAE occurred in 2 patients (16.7%), with acute myocardial infarction, and neutrophil count decrease respectively. The most common TRAEs were ALP elevation (33.3%) and AST elevation (25.0%). 12 patients completed at least one tumor evaluation. The DCR per RECIST 1.1 by investigator was 33.3% (4/12; 95% CI: 9.92 - 65.11), best overall response was SD. Pharmacokinetics were dose-proportional with a terminal half-life of 5.2-7.4 days across the dose range of 120-1200 mg. Conclusions: PM1009 was well-tolerated up to 1200 mg with signs of anti-tumor activity. These findings support further clinical investigation of PM1009 especially for the combination with chemotherapy or PD-1/L1-based checkpoint inhibitors. Clinical trial information: NCT05607563 .

Evaluating antitumor activity and response determinants to trastuzumab deruxtecan in pediatric solid tumors.

10049 Background: Trastuzumab deruxtecan (T-DXd) is an anti-HER2 antibody-drug conjugate (ADC) linked to a topoisomerase inhibitor FDA-approved for several indications, including the treatment of HER2+ breast and gastric cancer. Although HER2 amplification is uncommon in pediatric cancers, recent demonstration of T-DXd efficacy in HER2-low breast cancer patients prompted us to examine the potential clinical relevance of T-DXd in pediatrics by evaluating HER2 expression and activity of T-DXd in preclinical pediatric solid tumor models. Methods: Cell viability was assessed in a panel of histologically diverse pediatric solid tumor cell lines and 2 HER2-amplified adult cancer cell lines treated with T-DXd, payload (DXd), and a control IgG-ADC. HER2 protein expression in patient-derived xenograft (PDX) tumors was evaluated by immunohistochemistry (IHC) using 5 clinically validated anti-HER2 antibodies. RNAseq was performed on clinical (n=290) and PDX (n=184) tumors to determine relative expression of ERBB2. In vivo activity of T-DXd was evaluated in osteosarcoma (OS, n=10), Wilms tumor (WT, n=1) and malignant rhabdoid tumor (MRT, n=1) PDX models and a desmoplastic small round cell tumor (DSRCT) cell line xenograft model. Differences in tumor volume and time to disease progression was assessed and compared across treatments and models. Responses were correlated with HER2 expression by IHC. Results: In vitro, HER2-amplified control cell lines demonstrated a >30-fold reduction of IC50 when comparing T-DXd to ADC control. In contrast, the ADC control IC50 was nearly identical to T-DXd across all pediatric cancer cell lines, consistent with the absence of HER2 amplification in these models. We observed focal and membranous staining of HER2 by IHC in PDXs but was quite variable across antibodies tested: WT 0-17% HER2+ cases (n=6), MRT 0-40% (n=5), DSRCT 0-33% (n=24), OS 0-7% (n=30). ERBB2 gene expression was highest in DSRCT followed by WT, OS and MRT. In vivo efficacy studies demonstrated complete and partial responses in OS, WT, and DSRCT and improved disease control rates (OS: 67%, p=0.006, Mann-Whitney; WT: 100%; DSRCT: 100%). However, T-DXd and ADC control demonstrated similar activity in all tumor types with no consistent correlation between in vivo response and HER2 expression. Consistent with these preclinical studies, 4 patients with progressive DSRCT were treated with T-DXd via compassionate/off-label access with signs of clinical and radiographic responses. Conclusions: T-DXd shows significant preclinical antitumor activity across multiple pediatric solid tumors but little correlation with HER2 expression suggesting a mechanism of action similar to the clinical activity observed in HER2-low breast cancer. Xenograft efficacy studies and preliminary clinical experience with T-DXd in DSRCT patients warrant formal clinical trial investigation in this largely incurable disease.

Allogeneic chimeric antigen receptor T cells for children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia.

Chimeric antigen receptor (CAR) T-cell therapy has emerged as a breakthrough cancer therapy over the past decade. Remarkable outcomes in B-cell lymphoproliferative disorders and multiple myeloma have been reported in both pivotal trials and real-word studies. Traditionally, the use of a patient's own (autologous) T cells to manufacture CAR products has been the standard practice. Nevertheless, this approach has some drawbacks, including manufacturing delays, dependence on the functional fitness of the patient's T cells, which can be compromised by both the disease and prior therapies, and contamination of the product with blasts. A promising alternative is offered by the development of allogeneic CAR-cell products. This approach has the potential to yield more efficient drug products and enables the use of effector cells with negligible alloreactive potential and a significant CAR-independent antitumor activity through their innate receptors (i.e., natural killer cells, γδ T cells and cytokine induced killer cells). In addition, recent advances in genome editing tools offer the potential to overcome the primary challenges associated with allogeneic CAR T-cell products, namely graft-versus-host disease and host allo-rejection, generating universal, off-the-shelf products. In this review, we summarize the current pre-clinical and clinical approaches based on allogeneic CAR T cells, as well as on alternative effector cells, which represent exciting opportunities for multivalent approaches and optimized antitumor activity.

Combining the potency of a neoantigen-expressing DNA vector, an anti-CTLA-4 antibody, and an attenuated poxvirus in a personalized immunization platform: Preclinical studies of ODI-2001.

e14674 Background: Immune checkpoint inhibitors (ICI) have transformed cancer treatment. Their impressive effectiveness is crucially dependent on pre-existing neoepitope-specific immune responses. ODI-2001 aims at increasing the immune response against tumors by combining a DNA expressing multiple neoepitopes of the tumor, a MVA vaccinia virus as physiologic adjuvant and DNA carrier, and an anti-CTLA4 antibody as amplifier of the immune response. Methods: ODI-2001 was administered by repeated subcutaneous injections after tumor cells implantation in mice melanoma model B16F10 and colorectal cancer model CT26, and both before and after implantation in breast cancer model 4T1. In B16F10 model combination of ODI-2001 with anti-PD1 was assessed also. Neoepitopes were chosen from literature in B16F10 and CT26 models. In 4T1 model they were predicted using a dedicated neoepitope prediction algorithm (ImmunoEngine, myNEO, Gent, Belgium). Tumor volume and mice survival were assessed over time. Tumors were also analysed by immunofluorescence for immune cell infiltration. Each experiment received approval from the ethics committee for animals. Results: A significant improvement in survival was observed in mice treated with ODI-2001 in B16F10, and CT26 syngeneic mice models. In B16F10 the combination of ODI-2001 with anti-PD1 antibody demonstrated synergistic activity and a significant improvement in survival, while anti-PD1 alone or combined with anti-CTLA-4 failed to show any therapeutic effect (ODI-2001 + anti-PD1 vs. anti-CTLA-4 + anti-PD1 p<0.01). ODI-2001 treatment was associated with tumor rejections in the three animal models. In 4T1 model the ImmunoEngine epitope prediction algorithm demonstrated an improved efficacy as compared to a set of neoepitopes chosen from the literature. In B16F10, following immunization with ODI-2001, an increased CD8 immune cell infiltration of the tumor was documented. ODI-2001 was well tolerated by the treated animals. Conclusions: These data demonstrate a significant antitumoral activity of ODI-2001 as a neoantigen immunization platform across different preclinical cancer models, both in monotherapy and combined with anti-PD1. ODI-2001 represents a promising option to induce de novo cancer-specific immune responses, potentially increasing the proportion of patients responding to immunotherapy treatments. Based on this preclinical program a phase I with ODI-2001 in patients with advanced colorectal carcinoma is currently under preparation.

A phase I clinical trial investigating the safety, tolerability, and pharmacokinetics of HX301 (narazaciclib), a novel multi-kinase inhibitor targeting CSF1R, CDK 4/6, and ARK5, in patients with advanced solid tumors.

e15106 Background: HX301 (narazaciclib) is a promising novel multi-kinase inhibitor with potent activity against Colony Stimulating Factor 1 Receptor (CSF1R), Cyclin-Dependent Kinase 4/6 (CDK4/6), and Aurora Kinase 5 (ARK5), with a half-maximal inhibitory concentration (IC50) values in 0.29-4.95 nM range. It is an oral bioavailable agent and has the ability to cross blood-brain barrier. Preclinical data have showed significant antitumor activities, warranting further clinical trials to evaluate the safety, and potential efficacy in human subjects. Methods: Utilizing the standard 3+3 design, the study aimed to evaluate the safety, tolerability and pharmacokinetics of ascending doses of HX301. Patients with heavily pretreated advanced solid tumors received HX301single agent via oral administration, with doses ranging from 40mg to 200mg once daily for the first 21 days of each 28-day cycle. Results: As of December 27, 2023, a total of 20 patients (5 males, 15 females) were enrolled in the study, with varying doses of HX301 administered: 40 mg (n=3), 80 mg (n=3), 120 mg (n=4), 160 mg (n=3), and 200 mg (n=7). The median age of the patients was 55 years, ranging from 30 to 71. Notably, 15 patients (75%) had metastatic breast cancers. Dose-limiting toxicities (DLTs) were observed in 2 patients in the 200 mg group. These included a Grade 4 increase in alanine aminotransferase (ALT) and a Grade 3 decrease in platelet counts with associated epistaxis, both of which resolved after discontinuation of treatment. The most common treatment-related adverse events (AEs) observed were elevated aspartate aminotransferase (AST) (65.0%), decreased white blood cell count (50%), decreased neutrophil count (50%), elevated ALT (45%), elevated creatine kinase (45%), and elevated creatinine (35%). Additionally, 4 patients experienced Grade 3 or higher treatment-related AEs, including 1 patient in the 160 mg group with Grade 3 elevated γ-glutamyl transferase and alkaline phosphatase, and 3 patients in the 200 mg group with Grade 4 elevated ALT and Grade 3 elevated AST and Dyspepsia, Grade 3 decreased neutrophil and platelet counts, and Grade 3 hyperglycemia. Notably, no AEs led to death. Among the 20 patients evaluable for tumor assessment using RECIST 1.1 by Investigators, 4 obtained stable disease, including 2 patients in the 200 mg group, 1 in the 120 mg group, and 1 in the 80 mg group. Furthermore, 1 patient with HR+ breast cancer in the 200 mg group received study drug for over a year and achieved prolonged stable disease for more than 12 months, highlighting a notable clinical outcome. Conclusions: HX301 at dose levels ranging from 40mg to 160mg was tolerable with a manageable toxicity profile. Further clinical studies are needed to explore the drug's anti-tumor activity, particularly in combination settings. Clinical trial information: NCT05731934 .

VISTA‐targeted antibody‐drug conjugates exhibit potent antitumor effects on malignant pleural mesothelioma

AbstractMalignant pleural mesothelioma (MPM) is a malignant tumor of the pulmonary pleural tissue for which there is a lack of effective targeted therapy. In this study, moderate to high V‐domain immunoglobulin T‐cell activation suppressor (VISTA) expression levels were observed in most MPM clinical tumor samples. We prepared two high‐affinity anti‐VISTA monoclonal antibodies (mAbs) and generated two novel VISTA‐targeted antibody‐drug conjugates (ADCs) by conjugating anti‐VISTA mAbs with the potent cytotoxic drug monomethyl auristatin E (MMAE). αV1‐MMAE and αV2‐MMAE showed potent killing effects to VISTA‐positive cell lines in vitro, with half‐maximal inhibitory concentration (IC50) of nanomolar levels. αV1‐MMAE and αV2‐MMAE were also able to significantly induce apoptosis and cause G2/M phase arrest in VISTA‐positive cells. In the VISTA‐positive human MPM xenograft model, both αV1‐MMAE and αV2‐MMAE showed significant antitumor activity, led to a significant survival advantage compared to mice in the control group, and effectively induced apoptosis in the tumor tissues of mice. In conclusion, we demonstrated that the novel VISTA‐targeted ADCs (αV1‐MMAE and αV2‐MMAE), especially αV1‐MMAE, had potent killing effects against VISTA‐positive MPM cells both in vitro and in vivo. Therefore, through further development, they may have the potential to become new drugs for the treatment of MPM.

Advances in CAR-NK cell therapy for lung cancer: is it a better choice in the future?

Lung cancer remains one of the leading causes of cancer-related mortality worldwide necessitating the development of innovative therapeutic strategies. Chimeric antigen receptor (CAR) natural killer (NK) cell therapy represents a promising advancement in the field of oncology offering a novel approach to target and eliminate tumor cells with high specificity and reduced risk of immune-related adverse effects. This paper reviews the mechanism, potential targets, and recent advances in CAR-NK cell therapy for lung cancer, including the design and engineering of CAR-NK cells, preclinical studies, and the outcomes of early-phase clinical trials. We highlight the unique advantages of using NK cells, such as their innate ability to recognize and kill cancer cells and their reduced potential for inducing graft-versus-host disease (GvHD) and cytokine release syndrome (CRS) compared to CAR T-cell therapies. Results from recent studies demonstrate significant antitumor activity in lung cancer models with improved targeting and persistence of CAR-NK cells observed in vitro and in vivo. Finally, we discuss the challenges in optimizing CAR-NK cell therapies, including the potential resistance mechanisms. The paper concludes with an outlook on the future directions of CAR-NK cell research and its implications for lung cancer treatment emphasizing the importance of continued innovation and collaboration in the field.

Synthesis, structure and in vitro anticancer activity of copper(II) and platinum(II) complexes with pyrrol-appended dipicolylamine ligand

Copper complexes exhibit important potential applications as non-platinum based metallodrugs particularly in the field of anticancer research. In this paper, mononuclear copper(II) and platinum(II) complexes containing pyrrole-linked dipicolylamine, namely PPMdpa-Cu and PPMdpa-Pt, were synthesized and characterized. Among these complexes, PPMdpa-Cu exhibited a stronger ability to bind to CT-DNA (calf-thymus DNA) compared to PPMdpa-Pt. In addition, an MTT assay performed throughout our studies demonstrated that PPMdpa-Cu featured significant antitumor activity against the three cancer cell lines U87, AsPC-1 and HepG2, superior to that of PPMdpa-Pt as well as the ligand, PPMdpa. Particularly, the IC50 of PPMdpa-Cu against HepG2 was found to be as low as 27.3 μM. Finally, anticancer mechanism studies showed that PPMdpa-Cu could induce apoptosis in HepG2 cells associated with mitochondrial damage and oxidative stress caused by the generation of reactive oxygen species (ROS).

Unlocking the potential of icaritin derivatives: Synthesis, characterization, and antiproliferative activity against MCF-7 breast cancer cells

Natural products serve as ideal templates for drug development, and screening compounds derived from natural products has been a prominent and viable approach for discovering new drugs, especially in the field of cancer treatment. Icaritin (ICT), a prenylated flavonol glycoside natural product, has demonstrated significant anti-breast cancer activity. In this study, we used ICT as a template to chemically synthesize 16 icariin derivatives and evaluated their effects on the proliferation of the human breast cancer cell line MCF-7 using the CCK-8 assay. Eight of these compounds exhibited significant antitumor activity (IC50 < 20 μM), with the most potent compounds being T14 (IC50 = 2.69 ± 0.28 μM) and T16 (IC50 = 4.72 ± 0.63 μM). Through a structure-activity relationship (SAR) study of ICT, we determined the key features for ICT's in vitro anti-breast cancer activity: the presence of the 8-prenyl group is not essential for activity; the 7-OH group is crucial for activity; replacing the 6-H with a Minnich base enhances activity; acetylation of the 7-OH, 5-OH, and 3-OH groups significantly increases activity; and the nature of the substituent at the 3-OH group plays a critical role in activity, with even minor changes to the substituent having a significant impact on activity.

Design and one-pot synthesis of new substituted pyrrolo[1,2-a]thieno[3,2-e]pyrimidine as potential antitumor agents: in vitro and in vivo studies

A new efficient and versatile one-pot three-component synthesis of substituted pyrrolo[1,2-a]thieno[3,2-e]pyrimidine derivatives has been developed. It is based on a multistep cascade reaction from 2-aminothiophenes and 2-hydroxy-4-oxobut-2-enoic acids, and derivatives of cyanoacetic acid catalyzed by diisopropylethylamine. As a result, novel pyrrolo[1,2-a]thieno[3,2-e]pyrimidine derivatives (21 compounds) were synthesized in a mild reaction conditions with a high yield. The structures of the developed compounds were confirmed by NMR and elemental analysis. The influence of electron-withdrawing or electron-donor substituents on the antitumor activity of the developed compounds has been identified. In vitro screening analysis of 21 compounds revealed six lead candidates (12aa, 12dc, 12hc, 12ic, 12lb, and 12mb) that demonstrated the most significant antitumor activity against B16-F10, 4T1 and CT26 cells. Necrosis/apoptosis assay showed that apoptosis was the predominant mechanism of cell death. Molecular docking analysis revealed several potential targets for tested compounds, i.e. phosphatidylinositol 5-phosphate 4-kinase (PI5P4K2C), proto-oncogene serine/threonine-protein kinase (Pim-1), nicotinamide phosphoribosyltransferase (NAMPT) and dihydrofolate reductase (DHFR). The lead compound (12aa) can effectively induce cell apoptosis, possesses a high yield (98 %) and requires low-cost starting chemicals for its synthesis. In vivo experiments with melanoma-bearing mice confirmed that 12aa compound resulted in the significant tumor inhibition on 15 d after the therapy. In particular, tumor volume was ∼0.19 cm3 for 50 mg/kg versus ∼2.39 cm3 in case of untreated mice and tumor weight was ∼71.6 mg for 50 mg/kg versus ∼452.4 mg when considered untreated mice. Thus, our results demonstrated the high potential of the 12aa compound in the treatment of melanoma and can be recommended for further preclinical studies.

Enhanced anti-tumor efficacy with multi-transgene armed mesenchymal stem cells for treating peritoneal carcinomatosis

BackgroundMesenchymal stem cells (MSCs) have garnered significant interest for their tumor-tropic property, making them potential therapeutic delivery vehicles for cancer treatment. We have previously shown the significant anti-tumour activity in mice preclinical models and companion animals with naturally occurring cancers using non-virally engineered MSCs with a therapeutic transgene encoding cytosine deaminase and uracil phosphoribosyl transferase (CDUPRT) and green fluorescent protein (GFP). Clinical studies have shown improved response rate with combinatorial treatment of 5-fluorouracil and Interferon-beta (IFNb) in peritoneal carcinomatosis (PC). However, high systemic toxicities have limited the clinical use of such a regime.MethodsIn this study, we evaluated the feasibility of intraperitoneal administration of non-virally engineered MSCs to co-deliver CDUPRT/5-Flucytosine prodrug system and IFNb to potentially enhance the cGAS-STING signalling axis. Here, MSCs were engineered to express CDUPRT or CDUPRT-IFNb. Expression of CDUPRT and IFNb was confirmed by flow cytometry and ELISA, respectively. The anti-cancer efficacy of the engineered MSCs was evaluated in both in vitro and in vivo model. ES2, HT-29 and Colo-205 were cocultured with engineered MSCs at various ratio. The cell viability with or without 5-flucytosine was measured with MTS assay. To further compare the anti-cancer efficacy of the engineered MSCs, peritoneal carcinomatosis mouse model was established by intraperitoneal injection of luciferase expressing ES2 stable cells. The tumour burden was measured through bioluminescence tracking.ResultsFirstly, there was no changes in phenotypes of MSCs despite high expression of the transgene encoding CDUPRT and IFNb (CDUPRT-IFNb). Transwell migration assays and in-vivo tracking suggested the co-expression of multiple transgenes did not impact migratory capability of the MSCs. The superiority of CDUPRT-IFNb over CDUPRT expressing MSCs was demonstrated in ES2, HT-29 and Colo-205 in-vitro. Similar observations were observed in an intraperitoneal ES2 ovarian cancer xenograft model. The growth of tumor mass was inhibited by ~ 90% and 46% in the mice treated with MSCs expressing CDUPRT-IFNb or CDUPRT, respectively.ConclusionsTaken together, these results established the effectiveness of MSCs co-expressing CDUPRT and IFNb in controlling and targeting PC growth. This study lay the foundation for the development of clinical trial using multigene-armed MSCs for PC.

Inhibitory Effects of Soluble Dietary Fiber from Foxtail Millet on Colorectal Cancer by the Restoration of Gut Microbiota.

Colorectal cancer (CRC) is a common malignant tumor that occurs in the colon. Gut microbiota is a complex ecosystem that plays an important role in the pathogenesis of CRC. Our previous studies showed that the soluble dietary fiber of foxtail millet (FMB-SDF) exhibited significant antitumor activity in vitro. The present study evaluated the anticancer potential of FMB-SDF in the azoxymethane (AOM)- and dextran sodium sulfate (DSS)-induced mouse CRC models. The results showed that FMB-SDF could significantly alleviate colon cancer symptoms in mice. Further, we found that FMB-SDF consumption significantly altered gut microbiota diversity and the overall structure and regulated the abundance of some microorganisms in CRC mice. Meanwhile, KEGG pathway enrichment showed that FMB-SDF can also alleviate the occurrence of colon cancer in mice by regulating certain cancer-related signaling pathways. In conclusion, our findings may provide a novel approach for the prevention and biotherapy of CRC.

Metformin enhances the anti-tumor effects mediated by attenuated Salmonella typhimurium

In bacterial-based cancer therapy, while attenuated Salmonella treatment effectively inhibits tumor progression, single bacterial therapy struggles to completely suppress tumor growth and metastasis. Metformin, a natural compound derived from Galega officinalis L. and known for its antidiabetic properties, also demonstrates significant anti-tumor activity. However, the combined effect of metformin and attenuated Salmonella on tumor treatment has not been thoroughly investigated. In this study, we observed that metformin enhances attenuated Salmonella-mediated recruitment of tumor-infiltrating immune cells, such as NK cells, neutrophils, M1 macrophages, CD4+, and CD8+T lymphocytes in CT26 tumor-bearing mice. Furthermore, the combined treatment of metformin and attenuated Salmonella increases the protein expression of PEN2, PD1, and PD-L1. This finding is likely associated with the enhanced anti-tumor effects of S.t ΔppGpp by metformin, indicating that the combination of S.t ΔppGpp and metformin holds promise as a synergistic strategy for attenuated Salmonella-based immunotherapy.

Abstract PO1-18-05: Combination treatment with CDK2 inhibitor (BLU-222) and either palbociclib or ribociclib is synergistic in pre-clinical models of CDK4/6 inhibitor-resistant breast cancer

Abstract Background: Cyclin-dependent-kinase-4/6 inhibitors (CDK4/6 inhibitors) plus endocrine therapy (ET) is the standard of care first-line treatment for patients with hormone receptor (HR)-positive, HER2-negative metastatic breast cancer (MBC). However, since most patients progress following long-term treatment, resistance to CDK4/6 inhibitors plus ET remains a clinical problem with limited therapeutic options. Here we show that a potent and selective CDK2 inhibitor, BLU-222, while effective as a single agent, exhibited enhanced, synergistic activity when combined with palbociclib or ribociclib in both in vitro and in vivo (patient-derived xenografts-PDX) models of HR+/HER2- breast cancer resistant to CDK4/6 inhibitors. Methods: MCF7 and T47D palbociclib-resistant (PR) breast cancer cell lines were generated by culturing cells in media supplemented with increasing concentrations of palbociclib, starting at 1.2 µM and reaching a final concentration of 4.8 µM in a stepwise manner over a 6-month period. The single agent activity of BLU-222 and the combination effect of BLU-222 plus palbociclib in vitro were evaluated using the highest single agent model by SynergyFinder. The efficacy of BLU-222 as a single agent or in combination with palbociclib or ribociclib was also assessed in two PDX models (PR 1 and 2) from patients with acquired resistance (i.e. progressed following &amp;gt;6 months of treatment) to palbociclib plus letrozole treatment, and another two PDX models (PR 3 and 4) from patients who were intrinsically resistant (i.e. progressed following &amp;lt; 3 months of treatment) to palbociclib plus fulvestrant or letrozole, respectively. Results: In palbociclib-resistant MCF7 and T47D cells, protein levels of cyclin E and CDK2 were significantly upregulated, but Rb and p21 levels were downregulated compared to the parental cells. While these PR cells were completely refractory to palbociclib, they were significantly more sensitive to BLU-222. Moreover, combining BLU-222 with palbociclib demonstrated a strong synergistic effect in PR cells accompanied by enhanced apoptosis and cell cycle accumulation in G1 or G2/M phases. Consistent with these in vitro findings, combination treatment with BLU-222 (60 mg/kg; b.i.d.) and palbociclib (50 mg/kg; q.d.) or ribociclib (50 mg/kg; q.d.) exhibited significant antitumor activity in all four PDX models, as compared to either treatment alone. The combination of BLU-222 plus the CDK4/6 inhibitor induced durable tumor regression and prolonged survival, which continued unabated following drug removal. Mechanistically, treatment of PR cells and palbociclib-resistant PDX models with BLU-222 as a single agent, resulted in the induction of p21, which can sensitize the cells to palbociclib. Conclusions: These results show robust activity of BLU-222 in combination with CDK4/6 inhibitors in breast cancer cell lines and PDX models resistant to CDK4/6 inhibitors, providing a strong rationale for advancing BLU-222 plus CDK4/6 inhibitor treatment to clinical development in HR-positive/HER2-negative breast cancer patients who have progressed on CDK4/6 inhibitors. Citation Format: Linjie Luo, Juliana Navarro-Yepes, Yan Wang, Tuyen Bui, Nicole Kettner, Debu Tripathy, Kelly Hunt, Kerrie Faia, Khandan Keyomarsi. Combination treatment with CDK2 inhibitor (BLU-222) and either palbociclib or ribociclib is synergistic in pre-clinical models of CDK4/6 inhibitor-resistant breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-18-05.

Abstract PO5-12-12: Implementation of a comprehensive monitoring protocol for the prevention and treatment of interstitial lung disease in patients undergoing treatment with trastuzumab deruxtecan

Abstract Background: In the DESTINY-BREAST studies, Trastuzumab deruxtecan (T-DXd) demonstrated significant antitumor activity in heavily pretreated patients (pts) with HER2-positive and HER2-low advanced breast cancer (ABC). T-DXd is associated with an increased risk of interstitial lung disease (ILD), which occurs in 10-15% of patients with a 2.2% rate of fatal events. Increased monitoring for ILD within DESTINY-BREAST03 showed a reduction in grade 3-5 events. Patients with a history of clinically significant lung disease were excluded from this study, however this may not be reflective of the standard community patient population treated with T-DXd. There are currently no standardized monitoring protocols for ILD/pneumonitis for pts treated with T-DXd. We conducted a retrospective chart review to assess the benefit of implementing an ILD monitoring protocol in a cohort of patients receiving treatment with T-DXd at the Duke Cancer Institute. Methods: Patients with HER2-positive or HER2-low ABC who received ≥ five cycles of T-DXd between Jan 1, 2020- April 30, 2022 were included. Imaging with CT chest ILD protocol and pulmonary function testing with diffusing capacity for carbon monoxide (DLCO) were performed at baseline prior to initiation of T-DXd, prior to cycle 3 and cycle 5 in conjunction with ILD chest CT and then every 6 weeks to monitor for ILD. DLCO was corrected for hemoglobin. Clinical symptoms including cough, shortness of breath, dyspnea, and new or worsening respiratory symptoms were recorded. For pts that experienced more than a 10% decrease in corrected DLCO (DLCOc), a pulmonology consult was recommended. DLCOc was reviewed in combination with chest imaging and clinical history to evaluate for ILD and guidance was provided for continuation or cessation of T-DXd. Results: A total of 33 patients with HER2-positive (N=27) and HER2-low (N=6) ABC were monitored as per the predefined ILD monitoring protocol. There were 5 confirmed cases of ILD/pneumonitis within the pt cohort. 16 patients (48%) experienced DLCOc decreases &amp;gt;10% warranting a pulmonology consult or further review. Upon further assessment, ILD/pneumonitis was ruled out based on chest imaging and/or asymptomatic presentation in 11 patients and therapy continued without treatment delay or discontinuation. There were 5 confirmed cases of ILD/pneumonitis within the patient cohort. 3 of the 5 patients diagnosed with ILD experienced DLCOc decreases ≥10%, while 2 of the 5 diagnosed patients had DLCOc changes of &amp;lt; 10% but had concern for ILD on ILD/chest CT and were diagnosed after pulmonology consult. Additional results to be presented at meeting. Conclusion: For patients receiving T-DXd, implementation of a comprehensive protocol to monitor and assess for ILD secondary to treatment may allow patients with suspected ILD to begin treatment sooner or prevent permanent discontinuation by excluding ILD diagnosis. While PFT monitoring can be helpful for some patients to monitor for ILD, continuous PFT monitoring is not recommended for all patients given inconsistency. However, baseline PFTs prior to initiation and with suspected ILD in combination with imaging warrants further investigation. The use of a multidisciplinary team including pulmonologists experienced with T-DXd-induced ILD may assist in diagnosing or excluding ILD and allow for continuation of T-DXd therapy. Citation Format: Heather Moore, Kelly Westbrook, Thomas Bagwell, Scott Shofer, Carey Anders, Amy Guisinger, Olivia White, Susan Dent. Implementation of a comprehensive monitoring protocol for the prevention and treatment of interstitial lung disease in patients undergoing treatment with trastuzumab deruxtecan [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-12-12.

Abstract PO1-24-08: Targeting of HER3 potentiates the antitumor activity of paclitaxel against triple negative breast cancer

Abstract Background: Triple negative breast cancer (TNBC) is characterized by the absence of expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) overexpression. This aggressive form of breast cancer carries a higher risk of recurrence compared to other subtypes, presenting a significant clinical challenge. Although chemotherapy is commonly used as the primary treatment for a substantial number of TNBC patients, it is often accompanied by drug resistance and frequent tumor recurrence. Urgent efforts are needed to identify novel molecular targets specific to TNBC and develop effective therapies to combat this aggressive disease. The ultimate objective is to discover treatments capable of overcoming drug resistance and improving the overall survival of patients with TNBC. Methods: Immunohistochemistry was performed to examine the expression of HER3 in TNBC samples. Western blots were used to assess protein expression and activation. Cell proliferation and viability were determined by cell growth (MTS) assays. TCGA databases were analyzed to correlate HER3 mRNA expression with the clinical outcomes of TNBC patients. Specific shRNA was used to knockdown HER3 expression. LIVE/DEAD Cell Imaging was to detect live and dead cells. Orthotopic tumor models were established in nude mice to determine the capability of TNBC cells forming tumors and to test if our newly developed anti-HER3 monoclonal antibody (mAb) 4A7 could potentiate the antitumor activity of paclitaxel in vivo. Results: The chemo-resistant subline HCC1806-TR was obtained by subjecting TNBC HCC1806 cells to prolonged treatment with paclitaxel. In comparison to the parental cell line HCC1806-P, HCC1806-TR exhibited enhanced HER3 expression and activation. It is noteworthy that approximately half of the tested TNBC specimens and cell lines displayed elevated expression of HER3. Analyzing TCGA databases revealed that TNBC patients with high levels of HER3 mRNA expression in their tumors had significantly poorer overall survival (OS) and relapse-free survival (RFS) compared to those with low HER3 expression. Specifically knockdown of HER3 markedly inhibited TNBC cell proliferation and mammosphere formation in vitro and tumor growth in vivo. Blockade of HER3 signaling with our mAb (4A7) in combination with paclitaxel exerted significant antitumor activity against TNBC in vitro and in vivo. Conclusions: Our data demonstrate that increased HER3 is an effective therapeutic target for TNBC and our anti-HER3 mAb (4A7) may enhance the efficacy of paclitaxel in TNBC. Keywords: HER3, Anbibody, Chemotherapy, Triple Negative Breast Cancer Citation Format: Hui Lyu, Sanbao Ruan, Congcong Tan, Ann Thor, Bolin Liu. Targeting of HER3 potentiates the antitumor activity of paclitaxel against triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-24-08.

Abstract PO1-14-07: Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial)

Abstract Background: Immune checkpoint inhibitors (ICIs) have heralded a new era in breast cancer treatment; however, response rates remain limited, making precision immune-oncology a major unmet need. In addition to T cells, effective immune responses to ICIs rely on coordinated interactions between innate and adaptive immune cells. Mast cells are evolutionarily conserved, tissue-resident cells of importance to human health. Specific subsets of mast cells might be endowed with opposite roles in cancer treatment, yet the extent of mast cell heterogeneity and its clinical merit in immunotherapy remain undefined. Objective: We sought to comprehensively characterize mast cells in breast cancer, investigate their association with immunotherapy response with in-depth mechanistic insights, and identify actionable strategies to modulate mast cell functional states, thereby optimizing immunotherapy efficacy. Methods: We employed single-cell profiling on longitudinal breast cancer samples from three independent clinical trials (NCT04613674, NCT03197389 and GSE169246) to delineate mast cell heterogeneity in anti-PD-(L)1 therapy. By integrating multi-omic analyses, tissue characterization, preclinical experiments, transgenic mice, and high-throughput drug screening, we outlined the molecular features, underlying mechanisms, and clinical relevance of distinct mast cells to elicit ICI-responsive microenvironments. Subsequently, we launched RENAISSANCE (NCT05076682), a proof-of-concept, Bayesian adaptive, phase 2 platform trial, to evaluate the efficacy and safety of combining mast cell therapeutics with anti-PD-1 backbone therapy in metastatic triple-negative breast cancer (TNBC) patients who progressed after immunotherapy. The primary endpoint was the objective response rate (ORR) assessed using RECIST v1.1 criteria. Results: We identified a distinct population of mast cells termed antigen-presenting mast cells (APMCs), constituting approximately 30% of intratumoral mast cells and correlating with improved clinical benefit of anti-PD-(L)1 therapy in TNBC. APMCs displayed MHC-II and costimulatory molecules, and indicated the presence of tumor-reactive T cells and tertiary lymphoid structures. Using three immunocompetent mouse models, we confirmed the immunomodulatory capacity of APMCs in immunotherapy. Mechanistically, by employing Cpa3CreERT2Cd74fl/fl mice, we demonstrated that APMCs potentiate anti-PD-1 efficacy and antitumor T cell immunity through their antigen-presentation machinery. Interestingly, we identified cromolyn, an FDA-approved drug for allergy, as a potential therapeutic agent that elicited APMC-dependent CD8+ T cell cytotoxicity to synergize with anti-PD-1 therapy. Between February 2022 and March 2023, 10 patients with immunotherapy-refractory metastatic TNBC were enrolled to receive cromolyn plus camrelizumab backbone treatment. Given Bayesian predictive probability, this arm was “graduated” due to meeting the pre-specified efficacy boundary, with an ORR of 40.0% (4/10). The treatment was well tolerated with similar safety profiles of relevant drugs. Conclusions: Our findings provide crucial insights into the impact of mast cell heterogeneity on the clinical response to ICIs at a single-cell level, and pave the way for APMC-directed therapeutic interventions in cancer treatment. To our knowledge, this is the first prospective study in breast cancer of cromolyn plus anti-PD-1 backbone regimen after anti-PD-(L)1 immunotherapy failure, demonstrating significant antitumor activity and commendable tolerability. Consequently, we suggest a phase 3 randomized study to consolidate this finding, which might be an effective treatment in patients for whom there are few effective treatment options. Citation Format: Song-Yang Wu, Xi Jin, Yin Liu, Wen-Jia Zuo, Li Chen, Xiyu Liu, Lei Fan, Zhong-Hua Wang, Yan-Fei Liu, Yi-Zhou Jiang, Zhi-Ming Shao. Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-14-07.

Abstract PO4-27-05: A phase I open-label dose escalation trial of FWD1802 as monotherapy and in combination with palbociclib in patients with ER+/HER2- unresectable locally advanced or metastatic breast cancer with or without ESR1 mutations

Abstract Background: Estrogen receptor (ER) signaling sits at center of the tumor biology in ER+/HER2- breast cancers. Current standard of care involves hormone therapy with agents including selective estrogen receptor modulators (SERMs), selective estrogen receptor degraders (SERDs), and aromatase inhibitors (AIs). Unfortunately, most patients eventually develop resistance to these therapies. Mutations in estrogen receptor 1 (ESR1) are partially responsible for the acquired resistance. Mutated estrogen receptors are still sensitive to fulvestrant but with a much less sensitivity. In January 2023, elacestrant received its first approval for the treatment of postmenopausal women or adult men with breast cancer harboring ESR1 mutations in US. However, there is still great unmet medical need for this population. FWD1802 is a third-generation oral SERD for ER-positive breast cancer patients. It binds competitively to ER, with a much higher affinity than that of fulvestrant. Preclinically, FWD1802 alone and in combination with palbociclib exhibits significant anti-tumor activity in the ER+/HER2- models and in ESR1-mutated models in vitro and in vivo. This ongoing phase I study is to assess the safety, tolerability, pharmacokinetics (PK) and clinical activity of FWD1802 as monotherapy and in combination with palbociclib in ER+/HER2- unresectable locally advanced or metastatic breast cancer with or without ESR1 mutations. Methods: This clinical study (CTR20232130) consists of three parts: monotherapy dose escalation (Part A), dose escalation in combination with palbociclib (Part B) and monotherapy dose expansion in ESR1-mutated patients (Part C). A conventional “3+3” design is used for this study. Approximately a total of 129 patients will be enrolled. FWD1802 is administered orally daily. In monotherapy dose escalation study (Part A), at each dose level, a single ascending dose (SAD) is followed by a 28-day continuous multiple ascending dose (MAD) period (defined as 1 cycle). In Part B dose, palbociclib (125 mg daily) is administered on a 28-day treatment cycle with 21-day on treatment and 7-day off treatment, along with the 28-day treatment cycle of FWD1802. The primary objectives include dose limiting toxicity (DLT), maximum tolerated dose (MTD), safety, tolerability, and the recommended phase 2 dose (RP2D) of FWD1802. Secondary objectives include pharmacokinetics characteristics of FWD1802 and its major metabolite as monotherapy and in combination with palbociclib. Preliminary anti-tumor activity including objective response rate (ORR), duration of response (DoR), disease control rate (DCR) and progression-free survival (PFS) will also be evaluated. DLT evaluation will be conducted after the first cycle of multi-dose period, and tumor assessment will be conducted every 8 weeks by investigators according to RECIST version 1.1. Patients with ER+/HER2- unresectable locally advanced or metastatic breast cancer with or without ESR1 mutation are eligible for the enrollment. Enrolled patients should have progressed disease, or failed from previous therapy, or intolerable or inaccessible to standard therapy. In addition, patients with ECOG score ≤1 and with adequate renal, cardiac, hepatic, and hematologic function are eligible for enrollment. The monotherapy dose escalation (Part A) is currently ongoing. The dose selection for Part B and Part C will be based on the data from the ongoing Part A. Clinical trial information: CTR20232130. Research Sponsor: Shenzhen Forward Pharmaceuticals Co., Ltd. (FORWARD PHARMA). Citation Format: Ling Zeng, Jin Liu, Dan Wu, Huiwen Ge, Zirui Bian, Chenggang Zhu. A phase I open-label dose escalation trial of FWD1802 as monotherapy and in combination with palbociclib in patients with ER+/HER2- unresectable locally advanced or metastatic breast cancer with or without ESR1 mutations [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-27-05.

Development and Evaluation of a Novel Hyaluronic Acid and Chitosan-modified Phytosome for Co-delivery of Oxymatrine and Glycyrrhizin for Combination Therapy.

Multidrug resistance (MDR) of cancer cells is a major obstacle to efficient cancer chemotherapy. Combination therapy is expected to enhance the anticancer effect and reverse MDR. Numerous patents involve different kinds of nanoparticles for the co-delivery of multiple chemotherapeutics, but the FDA has approved none. In this study, oxymatrine (OMT) and glycyrrhizin (GL) were co-loaded into phytosomes as the core of nanocarriers, and the shell was cross-linked with chitosan (CS) and hyaluronic acid (HA) with the capability for the controlled, sequential release and the targeted drug uptake. Phospholipid complexes of OMT and GL (OGPs) were prepared by a solvent evaporation technique and could self-assemble in an aqueous solution to form phytosomes. CS and HA were sequentially coated on the surface of OGPs via electrostatic interactions to obtain CS coated OGPs (CS-OGPs) and HA modified CS-OGPs (HA-CS-OGPs), respectively. The particle size and zeta potential were measured to optimize the formulations. In vitro cytotoxicity and cellular uptake experiments on HepG2 cells were performed to evaluate the anticancer activity. OGPs were obtained with nano-size around 100 nm, and CS and HA coating on phytosomes could change the particle size and surface potential. The drug loading of OMT and GL showed that the nanocarriers could maintain a fixed ratio of 1:1. The in vitro release experiments indicated the release of OMT and GL was pH-dependent and sequential: the release of OMT from CS-OGPs and HA-CS-OGPs was significantly increased at pH 5.0 compared to the release at pH 7.4, while GL exhibited sustained released from CS-OGPs and HA-CS-OGPs at pH 5.0. Furthermore, in vitro cytotoxicity and cellular uptake experiments on HepG2 cells demonstrated that the co-delivery system based on phytosomes had significant synergistic anti-tumor activities, and the effects were enhanced by CS and HA modification. The delivery of OMT and GL via HA-CS-OGPs might be a promising treatment to reverse MDR in cancer therapy.

Small-Molecule Inhibitors of TIPE3 Protein Identified through Deep Learning Suppress Cancer Cell Growth In Vitro.

Tumor necrosis factor-α-induced protein 8-like 3 (TNFAIP8L3 or TIPE3) functions as a transfer protein for lipid second messengers. TIPE3 is highly upregulated in several human cancers and has been established to significantly promote tumor cell proliferation, migration, and invasion and inhibit the apoptosis of cancer cells. Thus, inhibiting the function of TIPE3 is expected to be an effective strategy against cancer. The advancement of artificial intelligence (AI)-driven drug development has recently invigorated research in anti-cancer drug development. In this work, we incorporated DFCNN, Autodock Vina docking, DeepBindBC, MD, and metadynamics to efficiently identify inhibitors of TIPE3 from a ZINC compound dataset. Six potential candidates were selected for further experimental study to validate their anti-tumor activity. Among these, three small-molecule compounds (K784-8160, E745-0011, and 7238-1516) showed significant anti-tumor activity in vitro, leading to reduced tumor cell viability, proliferation, and migration and enhanced apoptotic tumor cell death. Notably, E745-0011 and 7238-1516 exhibited selective cytotoxicity toward tumor cells with high TIPE3 expression while having little or no effect on normal human cells or tumor cells with low TIPE3 expression. A molecular docking analysis further supported their interactions with TIPE3, highlighting hydrophobic interactions and their shared interaction residues and offering insights for designing more effective inhibitors. Taken together, this work demonstrates the feasibility of incorporating deep learning and MD simulations in virtual drug screening and provides inhibitors with significant potential for anti-cancer drug development against TIPE3-.