Kill Tumor Cells Research Articles

Absence of ATM leads to altered NK cell function in mice

Ataxia-telangiectasia (A-T) is a rare disorder caused by genetic defects of A-T mutated (ATM) kinase, a key regulator of stress response, and characterized by neurodegeneration, immunodeficiency, and high incidence of cancer. Here we investigated NK cells in a mouse model of A-T (Atm−/−) showing that they are strongly impaired at killing tumor cells due to a block of early signaling events. On the other hand, in Atm−/− littermates with thymic lymphoma NK cell cytotoxicity is enhanced as compared with ATM-proficient mice, possibly via tumor-produced TNF-α. Results also suggest that expansion of exhausted NKG2D+ NK cells in Atm−/− mice is driven by low-level expression of stress-inducible NKG2D ligands, whereas development of thymoma expressing the high-affinity MULT1 ligand is associated with NKG2D down-regulation on NK cells.These results expand our understanding of immunodeficiency in A-T and encourage exploring NK cell biology in A-T patients in the attempt to identify cancer predictive biomarkers and novel therapeutic targets.

Structural and functional characterization of IgG- and non-IgG-based T-cell-engaging bispecific antibodies

Bispecific T-cell-engaging antibodies are a growing class of therapeutics with numerous molecules being tested in clinical trials and, currently, seven of them have received market approval. They are structurally complex and function as adaptors to redirect the cytotoxicity of T cells to kill tumor cells. T-cell-engaging bispecific antibodies can be generally divided into two categories: IgG/IgG-like and non-IgG-like formats. Different formats may have different intrinsic potencies and physiochemical properties, and comprehensive studies are needed to gain a better understanding of how the differences in formats impact on structural and functional characteristics. In this study, we designed and generated bispecific T-cell-engaging antibodies with IgG-like (DVD-Ig) and non-IgG (BiTE) formats. Both target the same pair of antigens (EGFR and CD3) to minimize the possible influence of targets on functional characterization. We performed a side-by-side comparison to assess differences in the physiochemical and biological properties of these two bispecific T-cell-engaging antibodies using a variety of breast and ovarian cancer cell-based functional assays to delineate the structural–functional relationships and anti-tumor activities/potency. We found that the Fc portion of T-cell-engaging bispecific antibodies can significantly impact antigen binding activity, potency, and stability in addition to eliciting different mechanisms of action that contribute the killing of cancer cells.

Engineering Dimeric EGFR-directed IgA Antibodies Reveals a Central Role of CD147 during Neutrophil-mediated Tumor Cell Killing of Head and Neck Squamous Cancer Cells.

Human IgA Abs engage neutrophils for cancer immunotherapy more effectively than IgG Abs. Previous studies demonstrated that engineering approaches improved biochemical and functional properties. In this study, we report a novel, to our knowledge, IgA2 Ab against the epidermal growth factor receptor generated by protein engineering and polymerization. The resulting molecule demonstrated a covalent linkage of L and H chains and an effective polymerization by the joining chain. The engineered dimer outperformed its monomeric variant in functional experiments on Fab-mediated modes of action and binding to the Fc receptor. The capacity to engage neutrophils for Ab-dependent cell-mediated cytotoxicity (ADCC) of adherent growing target cancer cells was cell line dependent. Although the engineered dimer displayed a long-term efficacy against the vulva carcinoma cell line A431, there was a notable in-efficacy against human papillomavirus (HPV)- head and neck squamous cell carcinoma (HNSCC) cell lines. However, the highly engineered IgA Abs triggered a neutrophil-mediated cytotoxicity against HPV+ HNSCC cell lines. Short-term ADCC efficacy correlated with the target cells' epidermal growth factor receptor expression and the ability of cancer cell-conditioned media to enhance the CD147 surface level on neutrophils. Notably, the HPV+ HNSCC cell lines demonstrated a significant increment in releasing soluble CD147 and a reduced induction of membranous CD147 on neutrophils compared with HPV- cells. Although membranous CD147 on neutrophils may impair proper IgA-Fc receptor binding, soluble CD147 enhanced the IgA-neutrophil-mediated ADCC in a dose-dependent manner. Thus, engineering IgA Abs and impedance-based ADCC assays provided valuable information regarding the target-effector cell interaction and identified CD147 as a putative critical parameter for neutrophil-mediated cytotoxicity.

Multifunctional Biomimetic Liposomes with Improved Tumor-Targeting for TNBC Treatment by Combination of Chemotherapy, Anti-Angiogenesis and Immunotherapy.

Triple negative breast cancer (TNBC) featuring high relapses and metastasis showed limited clinical therapeutic efficiency with chemotherapy for the extremely complex tumor microenvironment (TME), especially angiogenesis and immunosuppression. Combination of anti-angiogenesis and immunotherapy holds promise for effective inhibition of tumor proliferation and invasion, while it remains challenging for specific targeting drug delivery to tumors and metastatic lesions. Here, a multifunctional biomimetic liposome loading Gambogic acid (G/R-MLP) was developed using Ginsenoside Rg3 (Rg3) to substitute cholesterol and cancer cell membrane coating, which was designed to increase long-circulating action by a low immunogenicity and specifically deliver Gambogic acid (GA) to tumor site and metastatic lesions by homologous targeting and glucose transporter (GLUT) targeting. After G/R-MLP accumulated in the primary tumors and metastatic nodules, it synergistically enhanced the anti-tumor efficacy of GA, effectively suppressing the tumor growth and lung metastasis by killing tumor cells, inhibiting tumor cell migration and invasion, achieving anti-angiogenesis and improving the anti-tumor immunity. All in all, the strategy combining chemotherapy, anti-angiogenesis and immunotherapy improved therapeutic efficiency and prolonged survival, providing a new perspective for the clinical treatment of TNBC. This article is protected by copyright. All rights reserved.

Metal–Organic Framework-Capped Gold Nanorod Hybrids for Combinatorial Cancer Therapy

Recently, nanomaterials have attracted extensive attention in cancer-targeting therapy and as drug delivery vehicles owing to their unique surface and size properties. Multifunctional combinations of nanomaterials have become a research hotspot as researchers aim to provide a full understanding of their nanomaterial characteristics. In this study, metal–organic framework-capped gold nanorod hybrids were synthesized. Our research explored their ability to kill tumor cells by locally increasing the temperature via photothermal conclusion. The specific peroxidase-like activity endows the hybrids with the ability to disrupt the oxidative balance in vitro. Simultaneously, chemotherapeutic drugs are administered and delivered by loading and transportation for effective combinatorial cancer treatment, thereby enhancing the curative effect and reducing the unpredictable toxicity and side effects of large doses of chemotherapeutic drugs. These studies can improve combinatorial cancer therapy and enhance cancer treatment.

GZ17-6.02 kills PDX isolates of uveal melanoma.

GZ17-6.02 has undergone phase I evaluation in patients with solid tumors (NCT03775525). The RP2D is 375 mg PO BID, with an uveal melanoma patient exhibiting a 15% reduction in tumor mass for 5 months at this dose. Studies in this manuscript have defined the biology of GZ17-6.02 in PDX isolates of uveal melanoma cells. GZ17-6.02 killed uveal melanoma cells through multiple convergent signals including enhanced ATM-AMPK-mTORC1 activity, inactivation of YAP/TAZ and inactivation of eIF2α. GZ17-6.02 significantly enhanced the expression of BAP1, predictive to reduce metastasis, and reduced the levels of ERBB family RTKs, predicted to reduce growth. GZ17-6.02 interacted with doxorubicin or ERBB family inhibitors to significantly enhance tumor cell killing which was associated with greater levels of autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5 or eIF2α were more protective than knock down of ATM, AMPKα, CD95 or FADD, however, over-expression of FLIP-s provided greater protection compared to knock down of CD95 or FADD. Expression of activated forms of mTOR and STAT3 significantly reduced tumor cell killing. GZ17-6.02 reduced the expression of PD-L1 in uveal melanoma cells to a similar extent as observed in cutaneous melanoma cells whereas it was less effective at enhancing the levels of MHCA. The components of GZ17-6.02 were detected in tumors using a syngeneic tumor model. Our data support future testing GZ17-6.02 in uveal melanoma as a single agent, in combination with ERBB family inhibitors, in combination with cytotoxic drugs, or with an anti-PD1 immunotherapy.

Hydrogen Therapy Reverses Cancer-Associated Fibroblasts Phenotypes and Remodels Stromal Microenvironment to Stimulate Systematic Anti-Tumor Immunity.

Tumor microenvironment (TME) plays an important role in the tumor progression. Among TME components, cancer-associated fibroblasts (CAFs) show multiple tumor-promoting effects and can induce tumor immune evasion and drug-resistance. Regulating CAFs can be a potential strategy to augment systemic anti-tumor immunity. Here, the study observes that hydrogen treatment can alleviate intracellular reactive oxygen species of CAFs and reshape CAFs' tumor-promoting and immune-suppressive phenotypes. Accordingly, a controllable and TME-responsive hydrogen therapy based on a CaCO3 nanoparticles-coated magnesium system (Mg-CaCO3) is developed. The hydrogen therapy by Mg-CaCO3 can not only directly kill tumor cells, but also inhibit pro-tumor and immune suppressive factors in CAFs, and thus augment immune activities of CD4+ T cells. As implanted in situ, Mg-CaCO3 can significantly suppress tumor growth, turn the "cold" primary tumor into "hot", and stimulate systematic anti-tumor immunity, which is confirmed by the bilateral tumor transplantation models of "cold tumor" (4T1 cells) and "hot tumor" (MC38 cells). This hydrogen therapy system reverses immune suppressive phenotypes of CAFs, thus providing a systematic anti-tumor immune stimulating strategy by remodeling tumor stromal microenvironment.

Ferroptosis inducers – erastin and analogues (review)

Introduction. Improving the efficacy of chemotherapy is a non-trivial task of modern oncology. Its successful solution requires knowledge in many fields, including physiology, pathology, clinical oncology, pharmacology and others. The search for small molecules that selectively kill tumor cells led to the accidental discovery of erastin.Text. Erastin is a unique molecule that has a quinazoline fragment in its structure. Not so long ago it became known that the antitumour effect of this compound is due to the induction of ferroptosis – an iron-dependent form of cell death caused by lipid peroxidation. Erastin is able to induce ferroptosis through various biochemical pathways, including blocking of cystine-glutamate transport channel of cell membrane and potential-dependent anion channel of mitochondria, as well as activation of p53 protein.Conclusion. Pharmacological induction of ferroptosis by erastin and its analogues represents a promising direction in cancer chemotherapy. In addition, erastin and its analogues are able to increase sensitivity to chemotherapy and radiation therapy, which allows us to talk about the possibility of their use in the combined treatment of malignant neoplasms.

Abstract B009: Targeting bladder cancer-macrophage interactions by SPARC peptides

Abstract Bladder cancer is one of the privileged cancers treated with two modalities of immune therapeutics: intravesical Bacille Calmette-Guérin (BCG) for non-muscle invasive disease and immune checkpoint inhibitors for advanced metastatic muscle invasive disease. However, recurrence, intolerance and adverse events are encountered in both modalities with limited second and third line treatment options. Clinical data indicated that pretreatment infiltration of bladder tumors with tumor associated macrophages (TAMs) is associated with BCG failure, resistance to standard of care chemo- and immune-therapy and poor disease outcome. Preclinical studies indicated that macrophage infiltration is the forerunner of carcinogen-induced preneoplastic bladder lesions and progresses throughout overt neoplastic and metastatic disease. Thus, TAMs represent a plausible therapeutic target for bladder cancer. Capitalizing on our earlier report that SPARC, as tumor suppressor of BCa, we developed peptides mapping the biologically active domains of SPARC and investigated their direct effect on tumor cell malignant phenotype. In tandem, we determined the effect of SPARC-peptides on macrophage differentiation, polarization, and anti-tumor effects. We identified a potent inhibitory effect of our peptides on a panel of bladder cancer cell survival and invasiveness in 2D and 3D cultures. Using macrophage cell lines as well as bone marrow-derived myeloid cells, we found these peptides induced an M1 phenotype in response to cytokine stimulation, with enhanced phagocytic activity and macrophage-induced tumor cell killing in vitro. Moreover, SPARC-peptides inhibited macrophage polarization to M2 phenotype. Our data strongly suggest that SPARC-peptides are promising therapeutic candidates for bladder cancer. Citation Format: Mariam Diab, Neveen Said. Targeting bladder cancer-macrophage interactions by SPARC peptides [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr B009.

A targeting multiple-stimuli responsive POSS-based smart nanomaterial for enhanced chemo-photothermal synergistic therapy

The combination of chemotherapy and photothermal therapy has garnered significant attention in the field of multimodal cancer therapy. However, achieving precise and controllable delivery of therapeutic agents remains a challenge. In this study, we designed a biocompatible smart nanomaterial (PSD-FA) for efficient loading of doxorubicin (DOX) through dynamic chemical bonding, with the aim of achieving responsive behavior to both the tumor microenvironment (TME) and external laser irradiation. The incorporation of PEG into the nanoplatform enhanced hydrophilicity of PSD-FA NPs. Folic acid (FA) served as a targeting ligand to guide the nanoparticles tumor sites. On one hand, SQ-N acted as an effective photothermal agent that efficiently converted light energy into heat energy upon stimulation by exogenous near-infrared light. This localized increase in temperature at the tumor site facilitated targeted killing of tumor cells. On the other hand, after photothermal therapy-induced tumor ablation, DOX was released in response to redox stimuli due to significantly higher concentrations of glutathione (GSH), an antioxidant presents in TME. This allowed deep penetration into the tumor tissue, expanding the attack area and inhibiting nucleic acid synthesis in tumor cells, ultimately leading to cell death. Both in vitro and in vivo experiments demonstrated excellent anticancer efficacy of PSD-FA NPs. Overall, this intelligent nanomaterial successfully achieved targeted drug delivery with redox-responsive release capabilities while synergistically combining chemo-photothermal therapies, thus exhibiting great potential for clinical applications.

Zebularine potentiates anti-tumor immunity by inducing tumor immunogenicity and improving antigen processing through cGAS-STING pathway

DNA methylation is an important epigenetic mechanism involved in the anti-tumor immune response, and DNA methyltransferase inhibitors (DNMTi) have achieved impressive therapeutic outcomes in patients with certain cancer types. However, it is unclear how inhibition of DNA methylation bridges the innate and adaptive immune responses to inhibit tumor growth. Here, we report that DNMTi zebularine reconstructs tumor immunogenicity, in turn promote dendritic cell maturation, antigen-presenting cell activity, tumor cell phagocytosis by APCs, and efficient T cell priming. Further in vivo and in vitro analyses reveal that zebularine stimulates cGAS-STING-NF-κB/IFNβ signaling to enhance tumor cell immunogenicity and upregulate antigen processing and presentation machinery (AgPPM), which promotes effective CD4+ and CD8+ T cell-mediated killing of tumor cells. These findings support the use of combination regimens that include DNMTi and immunotherapy for cancer treatment.

Homologous-targeting biomimetic nanoparticles co-loaded with melittin and a photosensitizer for the combination therapy of triple negative breast cancer.

Melittin (Mel) is considered a promising candidate drug for the treatment of triple negative breast cancer (TNBC) due to its various antitumor effects. However, its clinical application is hampered by notable limitations, including hemolytic activity, rapid clearance, and a lack of tumor selectivity. Here, we designed novel biomimetic nanoparticles based on homologous tumor cell membranes and poly(lactic-co-glycolic acid) (PLGA)/poly(beta-aminoester) (PBAE), denoted MDM@TPP, which efficiently coloaded the cytolytic peptide Mel and the photosensitizer mTHPC. Both in vitro and in vivo, the MDM@TPP nanoparticles effectively mitigated the acute toxicity of melittin and exhibited strong TNBC targeting ability due to the homologous targeting effect of the tumor cell membrane. Under laser irradiation, the MDM@TPP nanoparticles showed excellent photodynamic performance and thus accelerated the release of Mel by disrupting cell membrane integrity. Moreover, Mel combined with photodynamic therapy (PDT) can synergistically kill tumor cells and induce significant immunogenic cell death, thereby stimulating the maturation of dendritic cells (DCs). In 4T1 tumor-bearing mice, MDM@TPP nanoparticles effectively inhibited the growth and metastasis of primary tumors and finally prevented tumor recurrence by improving the immune response.

Biogated mesoporous silica nanoagents for inhibition of cell migration and combined cancer therapy.

Migration is an initial step in tumor expansion and metastasis; suppressing cellular migration is beneficial to cancer therapy. Herein, we designed a novel biogated nanoagents that integrated the migration inhibitory factor into the mesoporous silica nanoparticle (MSN) drug delivery nanosystem to realize cell migratory inhibition and synergistic treatment. Antisense oligonucleotides (Anti) of microRNA-330-3p, which is positively related with cancer cell proliferation, migration, invasion, and angiogenesis, not only acted as the locker for blocking drugs but also acted as the inhibitory factor for suppressing migration via gene therapy. Synergistic with gene therapy, the biogated nanoagents (termed as MSNs-Gef-Anti) could achieve on-demand drug release based on the intracellular stimulus-recognition and effectively kill tumor cells. Experimental results synchronously demonstrated that the migration suppression ability of MSNs-Gef-Anti nanoagents (nearly 30%) significantly contributed to cancer therapy, and the lethality rate of the non-small-cell lung cancer was up to 70%. This strategy opens avenues for realizing efficacious cancer therapy and should provide an innovative way for pursuing the rational design of advanced nano-therapeutic platforms with the combination of cancer cell migratory inhibition.

IL-15/IL-15Rα-Fc fusion protein XmAb24306 potentiates activity of CD3 bispecific antibodies through enhancing T cell expansion.

Insufficient quantity of functional T cells is a likely factor limiting clinical activity of T cell bispecific antibodies, especially in solid tumor indications. We hypothesized that XmAb24306 (efbalropendekin alfa), a lymphoproliferative interleukin (IL)-15/IL-15 receptor α (IL-15Rα) Fc-fusion protein, may potentiate the activity of T cell dependent (TDB) antibodies. Activation of human peripheral T cells by cevostamab, an anti-FcRH5/CD3 TDB, or anti-HER2/CD3 TDB resulted in upregulation of IL-2/15Rβ (CD122) receptor subunit in nearly all CD8+ and majority of CD4+ T cells, suggesting that TDB treatment may sensitize T cells to the IL-15. XmAb24306 enhanced T cell bispecific antibody induced CD8+ and CD4+ T cell proliferation and expansion. In vitro combination of XmAb24306 with cevostamab or anti-HER2/CD3 TDB resulted in significant enhancement of tumor cell killing, which was reversed when T cell numbers were normalized, suggesting that T cell expansion is the main mechanism for the observed benefit. Pre-treatment of immune competent mice with a mouse-reactive surrogate of XmAb24306 (mIL-15-Fc) resulted in significant increase of T cells in blood, spleen and in tumors and converted transient anti-HER2/CD3 TDB responses to complete durable responses. In summary, our results support the hypothesis where the number of tumor infiltrating T cells is rate limiting for the activity of solid tumor targeting TDBs. Upregulation of CD122 by TDB treatment and the observed synergy with XmAb24306 and T cell bispecific antibodies supports clinical evaluation of this novel immunotherapy combination.

Conformation-Switchable Polypeptides as Molecular Gates for Controllable Drug Release.

The control over secondary structure has been widely studied to regulate the properties of polypeptide materials, which is used to change their functions in situ for various biomedical applications. Herein, we designed and constructed enzyme-responsive polypeptides as gating materials for mesoporous silica nanoparticles (MSNs), which underwent a distorted structure-to-helix transition to promote the release of encapsulated drugs. The polypeptide conjugated on the MSN surface adopted a negatively charged, distorted, flexible conformation, covering the pores of MSN to prevent drug leakage. Upon triggering by alkaline phosphatase (ALP) overproduced by tumor cells, the polypeptide transformed into positively charged, α-helical, rigid conformation with potent membrane-penetrating capabilities, which protruded from the MSN surface to uncover the pores. Such a transition thus enabled cancer-selective drug release and cellular internalization to efficiently kill tumor cells. This study highlights the important role of chain flexibility in modulating the biological function of polypeptides and provides a new application paradigm for synthetic polypeptides with secondary-structure transition.

Mg-ZIF nanozymes disrupt the level of ROS for osteosarcoma killing via POD activity.

Osteosarcoma (OS) is notorious for its high malignancy, and conventional chemotherapy drugs, while killing tumor cells, often inflict significant harm on the patient's body. The tumor microenvironment of OS is characterized by high levels of hydrogen peroxide (H2O2). Leveraging this feature, we have developed Mg-ZIF nanoparticles, which incorporate magnesium (Mg) to confer robust peroxidase (POD)-like enzymatic activity. These Mg-ZIF nanozymes can generate highly lethal superoxide anions within tumor cells in a responsive manner, thereby achieving effective tumor destruction. Both in vitro and in situ OS models have corroborated the anti-tumor efficacy of Mg-ZIF nanozymes, while also validating their biosafety. The design of Mg-ZIF nanozymes opens a new avenue for the treatment of OS, offering a promising therapeutic strategy.

Combination immunotherapy with vaccine and oncolytic HSV virotherapy is time dependent.

Oncolytic virotherapy or immunovirotherapy is a strategy that utilizes viruses to selectively infect and kill tumor cells while also stimulating an immune response against the tumor. Early clinical trials in both pediatric and adult patients using oncolytic herpes simplex viruses (oHSVs) have demonstrated safety and promising efficacy; however, combinatorial strategies designed to enhance oncolysis while also promoting durable T cell responses for sustaining disease remission are likely required. We hypothesized that combining the direct tumor cell killing and innate immune stimulation by oHSV with a vaccine that promotes T cell mediated immunity may lead to more durable tumor regression. To this end, we investigated the preclinical efficacy and potential synergy of combining oHSV with a self-assembling nanoparticle vaccine co-delivering peptide antigens and Toll-like receptor-7 and -8 agonists (TLR-7/8a) (referred to as SNAPvax™), that induces robust tumor specific T cell immunity. We then assessed how timing of the treatments (i.e., vaccine before or after oHSV) impacts T cell responses, viral replication, and preclinical efficacy. The sequence of treatments was critical, as survival was significantly enhanced when the SNAPvax™ vaccine was given prior to oHSV. Increased clinical efficacy was associated with reduced tumour volume and increases in virus replication and tumor antigen specific CD8+ T cells. These findings substantiate the criticality of combination immunotherapy timing and provide preclinical support for combining SNAPvax with oHSV as a promising treatment approach for both pediatric and adult tumors.

A dual gene combination therapy approach by KRAS-G12V gene editing and SLC25A22 gene silencing for KRAS-mutant colorectal cancer

KRAS gene is mutated in 40% of colorectal cancers (CRC), which induces malignant proliferation by regulating cellular nutrient metabolism and biosynthesis. It has been found that malignant proliferation of KRAS-mutant colorectal cancer relies on the upregulation of SLC25A22 protein expression, suggesting that inhibition the expression of both KRAS and SLC25A22 is a potential CRC therapeutics. Stably knocking down the oncogenic KRAS-G12V gene can achieve long-term gene therapy effects, while transient downregulation of SLC25A22, a normal functional gene most of the time, is preferred to kill tumor cells and minimize the side impact on normal cells. Here, two lipid nanoparticles (LNP) were designed to encapsulate KRAS-G12V CRISPR/Cas9 gene editing plasmids (pKRAS-LNPs) and SLC25A22 siRNA (siSLC-LNPs), respectively. Therapeutic effects of both nanoparticles alone and in combination on KRAS-G12V mutant colorectal cancer cells in vitro were first examined. The result showed that delivery of pKRAS-LNPs or siSLC-LNPs alone could effectively achieve KRAS-G12V gene editing or SLC25A22 gene silencing and inhibit tumor cell proliferation, while co-delivery of both LNPs could achieve stronger inhibition of tumor cell proliferation by inducing stronger apoptosis. Furthermore, we found that co-delivery of pKRAS-LNPs and siSLC-LNPs induced stronger apoptosis and cell proliferation inhibition compared to pKRAS&siSLC-LNPs that were constructed by pre-mixing pKRAS and siSLC and then encapsulating them. Finally, we validated that co-delivery of pKRAS-LNPs and siSLC-LNPs can achieve KRAS-G12V colorectal cancer treatment in vivo with a tumor inhibition rate of 61.15%. In summary, the delivery vectors constructed for nucleic acids targeting KRAS and SLC25A22 achieved therapeutic targeting of KRAS-G12V colorectal cancer in vitro and in vivo.

Abstract PO3-04-05: Efficacy and safety of the recombinant humanized anti-HER2 monoclonal antibody-MMAE conjugate RC48-ADC in patients with HER2-positive or HER2-low expressing, metastatic breast cancer: a single-arm phase II study

Abstract Background: Current treatment options for HER2-positive (IHC 3+, or IHC 2+/FISH+) advanced or metastatic breast cancer at third-line and above have shown limited clinical benefit. There is no recommended HER2-targeting treatment for HER2-low expressing (IHC 2+/FISH-, or IHC 1+) population. RC48 (Disitamab vedotin), a newly developed antibody-drug conjugate (ADC), is comprised of three well-defined components: hertuzumab against the prominent tumor target-HER2, monomethyl auristatin E (MMAE) and a cleavable linker, with a bystanding effect in tumor cell killing. There is a lack of data on the administration of RC48 in the Chinese population. Here, we report the efficacy and safety of RC48-ADC in the advanced or metastatic breast cancer. Methods: Patients with HER2-positive or HER2-low expressing, locally advanced or metastatic breast cancer were eligible and received RC48 2.5 mg/kg every two weeks alone or combined with drugs with different anti-tumor mechanisms, such as immune checkpoint inhibitors (ICIs), tyrosine kinase inhibitors (TKIs) and antiangiogenic compounds. The primary endpoint was the objective response rate (ORR) assessed by the primary researcher. Secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR), time to progression, and safety. Results: At the time of data cutoff (June 30, 2023), 120 chinese female breast cancer patients were enrolled and treated with RC48-ADC. 82 patients (68.3%) were HER2-positive and 38 patients (31.7%) were HER2-low expressing. At baseline, 52 patients (43.3%) had liver metastases, 40 patients (33.3%) had brain metastases, 70 patients (58.3%) had ≥3 metastases lesions, and 84 patients (70.0%) had received ≥3 prior chemotherapy regimens. In the overall population, the ORR was 38.3% (95% confidence interval [CI]: 30.0%-47.3%). The median PFS was 5.7 months (95% CI: 4.6-6.9 months). The DCR was 64.2% (95% CI: 54.9%-72.6%). In the HER2-positive subgroup, the ORR and mPFS were 42.7% (95% CI: 32.0%-54.1%) and 6.3 months (95% CI: 4.9-7.6 months). In the HER2-low expressing subgroup, the ORR and mPFS were 29.0% (95% CI: 16.0%-46.1%) and 3.6 months (95% CI: 2.0-5.3 months). In addition, the mPFS in the dual drug combination-treated group were longer than those in the single drug treatment group, with mPFS of 7.1 months (95% CI: 5.0-9.2 months) and 4.6 months (95% CI: 3.5-5.8 months), respectively. The most frequently reported treatment-related adverse events (TRAEs) were increased AST (45.8%), increased ALT (41.7%), decreased white blood cell count (25.0%), and fatigue (25%), most were grade 1-2 in severity. Conclusions: RC48-ADC showed consistent efficacy in HER2-positive and HER2-low expressing subgroups. No new safety signals were observed. Coadministration with ICIs, TKIs and antiangiogenic compounds demonstrated substantially enhanced efficacy compared to the monotherapies and could be a future direction in development of ADC. Citation Format: Fei Qu, Wei Li, Yongmei Yin, Qian Liu. Efficacy and safety of the recombinant humanized anti-HER2 monoclonal antibody-MMAE conjugate RC48-ADC in patients with HER2-positive or HER2-low expressing, metastatic breast cancer: a single-arm phase II study [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 PO3-04-05.

Abstract PO5-27-10: Next generation antibody drug conjugates: Multi-payload conjugates targeting multiple mechanisms of cell killing

Abstract Background: ADCs have had tremendous impact on patient outcomes in breast cancer and are rapidly moving towards second line use. However, many patients fail to respond or relapse after treatment with ADC therapies due to tumor heterogeneity and resistance to ADC payloads. Method: CatenaBio has developed a novel Multi-Payload-Conjugate (MPC) system capable of attaching distinct payloads at different sites to the same antibody, enabling the production of single-molecule targeted combination therapies with defined DAR. Results: We screened combinations of different payloads targeting several different mechanisms attached to trastuzumab at different drug-antibody ratios to optimize tumor cell killing. These targeted combination ADCs demonstrated robust killing in both HER2 high and low tumor cell lines. Conclusion: Antibody Drug Conjugates have revolutionized the treatment of high HER2 positive breast cancer. More recently advances have been made in the design of ADCs to expand indications to include HER2 low as well as HER2 negative patients. These constructs offer the next step in ADC design and allow for the combination of multiple mechanisms of action in a single MPC that are highly effective across multiple breast cancer cell lines. These molecules offer the potential to circumvent tumor resistance pathways and deliver deeper and more durable responses. Disclosures: Marco Lobba, Devin Trinter, Maxwell Nguyen, Daniel Gutierrez, Samantha Brady, Chanez Symister, Andrew Lau, Richard Kendall, and Saurabh Johri are employed by Catena Biosciences. Matthew Francis is a co-founder and advisor to Catena Biosciences. Citation Format: Marco Lobba, Devin Trinter, Maxwell Nguyen, Daniel Gutierrez, Samantha Brady, Chanez Symister, Andrew Lau, Richard Kendall, Saurabh Johri, Matthew Francis. Next generation antibody drug conjugates: Multi-payload conjugates targeting multiple mechanisms of cell killing [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 PO5-27-10.