Bystander Effect Research Articles

A peptide-salinomycin conjugate with a bystander effect reduces the stemness characteristics of ovarian cancer cells and enhances drug sensitivity

Salinomycin (Sal) has attracted considerable attention in the field of tumor treatment, especially for its inhibitory effect on cancer stem cells (CSCs) and drug-resistant tumor cells. However, its solubility and targeting specificity pose significant challenges to its pharmaceutical development. Sal-A6, a novel peptide-drug conjugate (PDC), was formed by linking the peptide A6 targeting the CSC marker CD44 with Sal using a specific linker. This conjugation markedly enhances the physicochemical properties of Sal and compared to Sal, Sal-A6 demonstrated a significantly increased activity against ovarian cancer. Furthermore, Sal-A6, employing a disulfide bond as a linker, exhibited bystander killing effect. Moreover, it induces substantial cytotoxic effect on both cancer stem cells and drug-resistant cells in addition to enhance chemosensitivity of resistant ovarian cancer cells. In summary, the results indicated that Sal-A6, a novel PDC derived from Sal, has potential therapeutic applications in the treatment of ovarian cancer and drug-resistant patients. Additionally, this discovery offers insights for developing PDC-type drugs using Sal as a foundation.

Bystander Effect: Workplace Harassment of Women at Educational Institutes: A Case Study of the University of Okara

Bystander Effect: Workplace Harassment of Women at Educational Institutes: A Case Study of the University of Okara

T cell receptor-directed antibody-drug conjugates for the treatment of T cell-derived cancers

T cell-derived cancers are hallmarked by heterogeneity, aggressiveness, and poor clinical outcomes. Available targeted therapies are severely limited due to a lack of target antigens that allow discrimination of malignant from healthy T cells. Here we report a novel approach for the treatment of T cell diseases based on targeting the clonally rearranged T cell receptor displayed by the cancerous T cell population. As a proof of concept, we identified an antibody with unique specificity towards a distinct TCR and developed antibody-drug conjugates, precisely recognizing and eliminating target T cells while preserving overall T cell repertoire integrity and cellular immunity. Our anti-TCR antibody-drug conjugates demonstrated effective receptor-mediated cell internalization, associated with induction of cancer cell death with strong signs of apoptosis. Furthermore, cell proliferation-inhibiting bystander effects observed on target-negative cells may contribute to the molecules’ anti-tumor properties precluding potential tumor escape mechanisms. To our knowledge, this represents the first anti-TCR antibody-drug conjugate designed as custom-tailored immunotherapy for T cell-driven pathologies.

Abscopal Effects, Clastogenic Effects and Bystander Effects: 70 Years of Non-Targeted Effects of Radiation.

In vitro and invivo observations accumulated over several decades have firmly shown that the biological effects of ionizing radiation can spread from irradiated cells/tissues to non-targeted cells/tissues. Redox-modulated intercellular communication mechanisms that include a role for secreted factors and gap junctions, can mediate these non-targeted effects. Clearly, the expression of such effects and their transmission to progeny cells has implications for issues related to radiation protection. Their elucidation is also relevant towards enhancing the efficacy of cancer radiotherapy and reducing its impact on the development of normal tissue toxicities. In addition, the study of non-targeted effects is pertinent to our basic understanding of intercellular communications under conditions of oxidative stress. This review will trace the history of non-targeted effects of radiation starting with early reports of abscopal effects which described radiation induced effects in tissues distant from the site of radiation exposure. A related effect involved the production of clastogenic factors in plasma following irradiation which can induce chromosome damage in unirradiated cells. Despite these early reports suggesting non-targeted effects of radiation, the classical paradigm that a direct deposition of energy in the nucleus was required still dominated. This paradigm was challenged by papers describing radiation induced bystander effects. This review will cover mechanisms of radiation-induced bystander effects and the potential impacts on radiation protection and radiation therapy.

Zero-shot prediction of mutation effects with multimodal deep representation learning guides protein engineering

Mutations in amino acid sequences can provoke changes in protein function. Accurate and unsupervised prediction of mutation effects is critical in biotechnology and biomedicine, but remains a fundamental challenge. To resolve this challenge, here we present Protein Mutational Effect Predictor (ProMEP), a general and multiple sequence alignment-free method that enables zero-shot prediction of mutation effects. A multimodal deep representation learning model embedded in ProMEP was developed to comprehensively learn both sequence and structure contexts from ~160 million proteins. ProMEP achieves state-of-the-art performance in mutational effect prediction and accomplishes a tremendous improvement in speed, enabling efficient and intelligent protein engineering. Specifically, ProMEP accurately forecasts mutational consequences on the gene-editing enzymes TnpB and TadA, and successfully guides the development of high-performance gene-editing tools with their engineered variants. The gene-editing efficiency of a 5-site mutant of TnpB reaches up to 74.04% (vs 24.66% for the wild type); and the base editing tool developed on the basis of a TadA 15-site mutant (in addition to the A106V/D108N double mutation that renders deoxyadenosine deaminase activity to TadA) exhibits an A-to-G conversion frequency of up to 77.27% (vs 69.80% for ABE8e, a previous TadA-based adenine base editor) with significantly reduced bystander and off-target effects compared to ABE8e. ProMEP not only showcases superior performance in predicting mutational effects on proteins but also demonstrates a great capability to guide protein engineering. Therefore, ProMEP enables efficient exploration of the gigantic protein space and facilitates practical design of proteins, thereby advancing studies in biomedicine and synthetic biology.

AAV gene replacement therapy for treating MPS IIIC: Facilitating bystander effects via EV-mRNA cargo.

MPS IIIC is a lysosomal storage disease caused by mutations in heparan-α-glucosaminide N-acetyltransferase (HGSNAT), for which no treatment is available. Because HGSNAT is a trans-lysosomal-membrane protein, gene therapy for MPS IIIC needs to transduce as many cells as possible for maximal benefits. All cells continuously release extracellular vesicles (EVs) and communicate by exchanging biomolecules via EV trafficking. To address the unmet need, we developed a rAAV-hHGSNATEV vector with an EV-mRNA-packaging signal in the 3'UTR to facilitate bystander effects, and tested it in an in vitro MPS IIIC model. In human MPS IIIC cells, rAAV-hHGSNATEV enhanced HGSNAT mRNA and protein expression, EV-hHGSNAT-mRNA packaging, and cleared GAG storage. Importantly, incubation with EVs led to hHGSNAT protein expression and GAG contents clearance in recipient MPS IIIC cells. Further, rAAV-hHGSNATEV transduction led to the reduction of pathological EVs in MPS IIIC cells to normal levels, suggesting broader therapeutic benefits. These data demonstrate that incorporating the EV-mRNA-packaging signal into a rAAV-hHGSNAT vector enhances EV packaging of hHGSNAT-mRNA, which can be transported to non-transduced cells and translated into functional rHGSNAT protein, facilitating cross-correction of disease pathology. This study supports the therapeutic potential of rAAVEV for MPS IIIC, and broad diseases, without having to transduce every cell.

Abscopal Effect Demonstrated on [18F]FDG PET/CT in a Case of Renal Cell Carcinoma Postnephrectomy

Renal cell carcinoma accounts for 3% of all malignancies with many of them presenting with metastasis at the time of presentation. The abscopal effect, a phenomenon characterized by systemic bystander effects on nontargeted lesions due to local therapy, has been extensively studied in the context of radiotherapy and immunotherapy. However, documentation of the abscopal effect following surgery remains limited. We present a case of a 67-year-old Indian male diagnosed with clear cell renal cell carcinoma (RCC), who underwent left radical nephrectomy. Baseline staging and postnephrectomy follow-up scans with fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET-CT) revealed an FDG-avid primary lesion in the left kidney with metastasis to the left lung. Surprisingly, the follow-up FDG PET-CT scan demonstrated the resolution of the left lung metastasis, indicating the occurrence of the abscopal effect resulting from the local nephrectomy. This rare clinical observation highlights the potential of surgery to induce immunogenic tumor neoantigens release and inflammatory factors, leading to systemic antitumor effects. While the abscopal effect has been extensively studied in the context of radiotherapy and immunotherapy, there is a scarcity of studies reporting nephrectomy promoting such systemic effects. The combination of radiotherapy and immunotherapy has shown promising results in enhancing tumor immunosuppression and facilitating the abscopal effect. We report a case of RCC with lung metastasis showing abscopal effect with resolution of lung nodule postnephrectomy on 18-F-FDG PET-CT.

Low-Dose Ionizing Radiation Exposure on Human Male Gametes: Damage or Benefit.

With the improvement of medical devices for diagnosis and radiotherapy, concerns about the effects of low doses of ionizing radiation are also growing. There is no consensus among scientists on whether they might have beneficial effects on humans in certain cases or pose more risks, making the exposure unreasonable. While the damaging consequences of high-dose radiation have been known since the discovery of radioactivity, low-dose effects present a much bigger investigative challenge. They are highly specific and include radio-adaptive responses, bystander effects, and genomic instability. Current data regarding the consequences of exposure to low-dose radiation on the quality of male gametes and fertility potential are contradictory. The reports suggest two directions: indirect impact on male gametes-through spermatogenesis-or direct effects at low doses on already mature spermatozoa. Although mature gametes are used for observation in both models, they are fundamentally different, leading to varied results. Due to their unique physiological characteristics, in certain cases, exposure of spermatozoa to low-dose ionizing radiation could have positive effects. Despite the findings indicating no beneficial effects of low-dose exposure on male fertility, it is essential to research its impact on mature spermatozoa, as well.

Preclinical studies of BB-1701, a HER2-targeting eribulin-containing ADC with potent bystander effect and ICD activity.

Several HER2-targeting antibody-drug conjugates (ADC) have gained market approval for the treatment of HER2-expressing metastasis. Promising responses have been reported with the new generation of ADCs in patients who do not respond well to other HER2-targeting therapeutics. However, these ADCs still face challenges of resistance and/or severe adverse effects associated with their particular payload toxins. Eribulin, a therapeutic agent for the treatment of metastatic breast cancer and liposarcoma, is a new choice of ADC payload with a distinct mechanism of action and safety profile. We've generated a novel HER2-tageting eribulin-containing ADC, BB-1701. The potency of BB-1701 was tested in vitro and in vivo against cancer cells where HER2-expressing levels vary in a large range. Bystander killing effect and toxin-induced immunogenic cell death (ICD) of BB-1701 were also tested. In comparison with HER2-targeting ADCs with DM1 and Dxd payload, eribulin-containing ADC demonstrated higher in vitro cytotoxicity in HER2-low cancer cell lines. BB-1701 also effectively suppressed tumors in models resistant to DM1 or Dxd containing ADCs. Mode of action studies showed that BB-1701 had a significant bystander effect on HER2-null cells adjacent to HER2-high cells. In addition, BB-1701 treatment induced ICD. Repeated doses of BB-1701 in nonhuman primates showed favorable pharmacokinetics and safety profiles at the intended clinical dosage, route of administration, and schedule. The preclinical data support the test of BB-1701 in patients with various HER2-expressing cancers, including those resistant to other HER2-targeting ADCs. A phase I clinical trial of BB-1701 (NCT04257110) in patients is currently underway.

IL-6 knockdown in a model of the human bone marrow, abrogates DNA damage induction in bystander cells post-chemotherapy induced cytokine release syndrome

Following infection or exposure to therapeutic agents, an aggressive immune response may result, termed cytokine storm (CS) or cytokine release syndrome. Here the innate immune system becomes uncontrolled, leading to serious consequences including possible death. Patients surviving CS are at greater risk for de novo tumorigenesis, but it is unclear if any specific cytokines are directly responsible for this outcome. De novo tumorigenesis has been observed in donated cells exposed to CS following haematopoietic stem cell transplant (HSCT).Modelling HSCT, we firstly demonstrated the release of CS levels from the HS-5 human bone marrow stromal cell line, post-exposure to chemotherapy. We then exposed the TK6 lymphoblast cell line to healthy and storm doses of IL-6 and measured increased genotoxicity via the micronucleus assay. During HSCT, haematopoietic cells are exposed to a complex mix of cytokines, so to determine if IL-6 was integral in a chemotherapy-induced bystander effect, we attempted to inhibit IL-6 from HS-5 cells using resatorvid or siRNA, treated with chlorambucil or mitoxantrone, and then co-cultured with bystander TK6 cells. Whilst resatorvid did not reduce IL-6 and did not reduce micronuclei in the bystander TK6 cells, siRNA inhibition reduced IL-6 to healthy in vivo levels, and micronuclei aligned with untreated controls.Our data suggests that exposure to high IL-6 (in the absence of inflammatory cells) has potential to induce genetic damage and may contribute to de novo tumorigenesis post-CS. We suggest that for individuals with a pro-inflammatory profile, anti-IL-6 therapy may be an appropriate intervention to prevent complications post-CS.

Donor Muse Cell Treatment Without HLA-Matching Tests and Immunosuppressant Treatment.

The strength of stem cell therapy is the regeneration of tissues by synergistic pleiotropic effects. Among many stem cell types, mesenchymal stem cells (MSCs) that are comprised of heterogenous population are widely used for clinical applications with the expectation of pleiotropic bystander effects. Muse cells are pluripotent-like/macrophage-like stem cells distributed in the bone marrow, peripheral blood, and organ connective tissues as cells positive for the pluripotent surface marker stage-specific-embryonic antigen -3. Muse cells comprise ~1% to several percent of MSCs. While Muse cells and MSCs share several characteristics, such as mesenchymal surface marker expression and their bystander effects, Muse cells exhibit unique characteristics not observed in MSCs. These unique characteristics of Muse cells include selective homing to damaged tissue after intravenous injection rather than being trapped in the lung like MSCs, replacement of a wide range of damaged/apoptotic cells by differentiation through phagocytosis, and long-lasting immunotolerance for donor cell use. In this review, we focus on the basic properties of Muse cells clarified through preclinical studies and clinical trials conducted by intravenous injection of donor-Muse cells without HLA-matching tests or immunosuppressant treatment. MSCs are considered to differentiate into osteogenic, chondrogenic, and adipogenic cells, whereas the range of their differentiation has long been debated. Muse cells may provide clues to the wide-ranging differentiation potential of MSCs that are observed with low frequency. Furthermore, the utilization of Muse cells may provide a novel strategy for clinical treatment.

The Real Experience of Lay Responders Performing Cardiopulmonary Resuscitation: A Synthesis of Qualitative Evidence.

To synthesize qualitative evidence on the experience of lay responders performing cardiopulmonary resuscitation (CPR). Qualitative evidence synthesis was performed using the Thomas and Harden method. The PubMed, Cochrane Library, Web of Science, OVID Medline, Embase, CINAHL, CNKI, and WanFang databases were systematically searched. The quality of the research was assessed by the Critical Assessment Skills Program Tool (CASP). A total of 5,610 studies were identified, and 9 studies were included in the analysis. Four analytical themes were generated: emotional ambivalence before CPR, psychological tolerance during CPR, perceived experience after CPR, and enhancing psychological resilience. Lay responders face complicated psychological experience during CPR, which may be susceptible to psychological effects such as "loss aversion," "bystander effects" and "knowledge curse." In addition to the timely retraining of CPR, lay responders should be instructed to manage psychological distress and improve psychological resilience. More importantly, the psychological sequelae may be long-lasting, requiring ongoing psychological intervention and follow-up based on valuing transdisciplinarity across endeavours.

Efficacy and safety of recombinant humanized anti-HER2 antibody-MMAE conjugate (RC48) in neoadjuvant for HER2-positive breast cancer: A single-arm phase II study.

e12636 Background: Breast cancer patients who achieve pCR after neoadjuvant therapy have a relatively good prognosis. Whether antibody‐drug conjugates (ADCs) can replace traditional chemotherapy combined with dual-target therapy in neoadjuvant therapy still needs to be explored. RC48 is a novel recombinant human anti-HER2 monoclonal antibody conjugated with a microtubule inhibitor (MMAE) via a cleavable linker, which can effectively kill HER2-positive tumors as well as tumors with low or heterogeneous HER2 expression through the bystander effect. The purpose of this study was to evaluate the efficacy and safety of RC48 in neoadjuvant treatment of HER2-positive breast cancer. Methods: Patients with HER2-positive breast cancer (size>20mm) or confirmed axillary lymph node metastasis were eligible and received RC48 at a dose of 2.5mg/kg alone every 2 weeks for 6 cycles followed by surgery. EC was administered postoperatively every 21 days for 4 cycles. Trastuzumab combined with pertuzumab was administered for 1 year in the adjuvant setting. The primary endpoints were ORR and pCR rates. Results: 23 patients had been enrolled, and all of them had completed surgical treatment. The median age was 45(38-70) years. The current results showed that 13.0% (3/23) achieved pCR, 78.3% (18/23) achieved PR, and 8.7% (2/23) experienced PD. The ORR was 91.3%. 42% (5/12) of patients with initially positive axillary lymph nodes turned negative after surgery. 11.8% (2/17) HR-/HER2+ patients achieved pCR. According to the proportion of target lesion reduction, patients were divided into mild response (0-50%) and moderate-to-severe response (51%-100%). In the HR-/HER2+ subtype group, 23.5% (4/17) had a mild response, and 76.5% (13/17) had a moderate-to-severe response. 6 patients with HR+ have been enrolled, and 16.7% (1/6) of them achieved pCR. All of HR+ subtypes had a moderate-to-severe response. No relevant serious (grade 3/4) toxicity has been reported. Conclusions: The present data showed an acceptable pCR rate with RC48 in HER2-positive breast cancer. Although the pCR rate was lower than the traditional chemotherapy combined with targeted therapy, the effect of rapid reduction of tumor volume was better (the moderate-severe remission rate was 82.6%). For HR+/HER2+ breast cancer, the ORR in this study reached 100%, indicating that the novel ADC had a significant inhibitory effect on the crosstalk between ER and HER2. And it was expected that the Destiny Breast 11 study would show similar results. This scheme had a good negative conversion rate for patients with positive axillary lymph nodes. Finally, RC48 provided a neoadjuvant treatment option with low toxicity and high patient compliance for HER2-positive breast cancer. Clinical trial information: NCT05134519 .

Phase 3 study of disitamab vedotin with pembrolizumab vs chemotherapy in patients with previously untreated locally advanced or metastatic urothelial carcinoma that expresses HER2 (DV-001).

TPS4616 Background: Platinum-based chemotherapy (chemo) has been the standard first-line (1L) therapy for locally advanced or metastatic urothelial carcinoma (la/mUC). Recently, enfortumab vedotin, a nectin-4-directed antibody-drug conjugate (ADC) with a monomethyl auristatin E (MMAE) payload, plus pembrolizumab (pembro) showed improved survival over chemo. Human epidermal growth factor receptor 2 (HER2) expression (immunohistochemistry [IHC] 1+-3+) has been reported in approximately half of all patients (pts) across tumor types, including UC, and is a biomarker that may be associated with poor outcomes. Disitamab vedotin (DV; RC48-ADC) is an investigational ADC comprising a fully humanized HER2-directed monoclonal antibody, disitamab, conjugated to MMAE via a protease-cleavable mc-vc linker. DV elicits antitumor activity through multimodal mechanisms of action, including MMAE-mediated direct cytotoxicity, bystander effect, and immunogenic cell death. DV has shown encouraging activity with a manageable safety profile in pts with la/mUC—as a single agent in a HER2-expressing post-platinum setting (IHC 3+/2+; ORR, 50.5%; median [m]PFS, 5.9 months; mOS, 14.2 months) and in combination with a programmed cell death protein 1 (PD-1) inhibitor in all comers (ORR, 76.0% in treatment-naive pts; 83.3%, 64.3%, and 33.3% in HER2 IHC 3+/2+, IHC 1+, and IHC 0 subgroups, respectively). Improved outcomes observed with an MMAE payload plus PD-1 inhibition across the ADC landscape, along with DV data, provide a robust rationale for this phase 3 trial of DV with pembro in the 1L setting for HER2-expressing la/mUC. Methods: DV-001 (NCT05911295) is an open-label, randomized, multicenter, controlled phase 3 trial evaluating DV with pembro vs chemo in pts with previously untreated HER2-expressing la/mUC. Pts will be randomized 1:1 to Arm A or B. Pts in Arm A will receive DV IV every 2 weeks and pembro IV every 6 weeks. Treatment will continue until disease progression or intolerable toxicity; pembro will be administered for a maximum of 18 6-weekly infusions (approximately 2 years). Pts in Arm B will receive platinum-based chemo with gemcitabine IV on Days 1 and 8 of every 3-week cycle, and either cisplatin or carboplatin on Day 1 of every 3-week cycle for 4-6 cycles. Maintenance therapy with avelumab after completion of chemo may be given to eligible pts where approved and available. Pts must have previously untreated la/mUC, measurable disease per RECIST v1.1, ECOG PS of 0-2 and must be eligible for platinum-based chemo. HER2 expression must be determined using the VENTANA 4B5 HER2 IHC Assay centrally and using the most recent archival or fresh tumor sample. Primary endpoints include PFS per blinded independent central review and OS. Enrollment is ongoing in the US, Canada, and Australia and is planned globally. Clinical trial information: NCT05911295 .

Updated safety and antitumor activity of BB-1701 from study 101 in the multiple dose level cohort of patients with locally advanced/metastatic HER2-low expressing breast cancer.

1110 Background: BB-1701 is an antibody-drug conjugate (ADC) consisting of a humanized anti-HER2 antibody and eribulin. After BB-1701 is internalized in HER2 expressing cancer cells, free eribulin is cleaved from the ADC by cathepsin b and causes cytotoxicity to cancer cells. The neighboring cells are affected with bystander effects, like cytotoxicity on tumor cells and non-cytotoxic effects on microenvironment by free eribulin. Here, we report updated results from the ongoing cohort expansion of the first-in-human phase I study (NCT 04257110). Methods: Patients enrolled were ≥18 years of age; had confirmed locally advanced/metastatic HER2 low-expressing (IHC 2+ and FISH negative, or IHC 1+; tested before enrollment) breast cancer; disease progression after ≥2 lines of prior standard therapies; an ECOG PS <2; and measurable lesion(s) (per RECIST v1.1). Four dose levels of BB-1701 (1.0, 1.2, 1.4 and 1.6 mg/kg) were administered during the cohort expansion. Results: As of 31 January 2024, 40 pts with HER2 low-expressing breast cancer were enrolled, 5 at 1.0 mg/kg, 20 at 1.2 mg/kg, 5 at 1.4 mg/kg and 10 at 1.6 mg/kg. Median age was 55 years, 97.5% ps were female, and 30.0%/70.0% pts had ECOG PS 0/1. The median number of prior lines of systemic therapy was 3. The most common (≥20%) all grade treatment-related adverse events (TRAEs) were peripheral neuropathy, AST increased, ALT increased, anemia, WBC decreased and hypertriglyceridemia. The most common (≥ 5%) grade 3 TRAEs were peripheral neuropathy and peripheral sensory neuropathy. There were no grade 4 or grade 5 events. Four treatment related serious adverse events were peripheral sensory neuropathy, anemia, spinal compression fracture and infusion related reaction. One patient discontinued BB-1701 treatment due to peripheral neuropathy. Of the 40 pts, 38 were evaluable for efficacy. At 1.0 mg/kg dose level, there were 2 partial response (PR), 2 stable disease (SD), with disease control rate (DCR) of 80.0% and 6-month PFS rate of 20%. At 1.2 mg/kg dose level, there were 5 PR, 11 SD with DCR of 88.9% and 6-month PFS rate of 50%. At 1.4 mg/kg dose level, there were 2 PR, 2 SD with DCR of 80.0% and 6-month PFS rate of 40%. At 1.6 mg/kg dose level, there were 1 complete response (CR), 2 PR with objective response rate of 30.0%, DCR of 60.0% and 6-month PFS rate of 50%. Among the 10 pts at 1.6 mg/kg dose level, 1 pt who had previously been treated with disitamab vedotin maintain CR and has been treated by BB-1701 for 9 months, and 1 pt who had previously been treated with trastuzumab deruxtecan maintain PR and has been treated by BB-1701 for 12 months. Conclusions: BB-1701 shows promising antitumor activity and a manageable safety profile in HER2 low-expressing breast cancer, including patients who received prior anti-HER2 ADCs. Clinical trial information: NCT04257110 .

Sacituzumab tirumotecan (SKB264/MK-2870) in patients (pts) with previously treated locally recurrent or metastatic triple-negative breast cancer (TNBC): Results from the phase III OptiTROP-Breast01 study.

104 Background: TROP2 (trophoblast cell surface antigen 2) is highly expressed in TNBC and is associated with worse survival. Sacituzumab tirumotecan (SKB264/MK-2870) is a TROP2 ADC developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. The hydrolytically linker permits both extracellular pH-sensitive cleavage and intracellular enzymatic cleavage to release the membrane permeable payload enabling the “bystander effect”. Here, we report the results from a phase Ⅲ study of sacituzumab tirumotecan in pts with advanced TNBC (OptiTROP-Breast01, NCT05347134). Methods: In this randomized phase Ⅲ trial, SKB264 was compared with physician's choice of chemotherapy (eribulin, vinorelbine, capecitabine, or gemcitabine) in pts with locally recurrent or metastatic TNBC who had received two or more prior therapies including at least one for metastatic setting. The primary endpoint was progression-free survival (PFS) by blinded independent central review (BICR). The TROP2 expression was determined by immunohistochemistry (IHC) using the semi-quantitative H-score method. Results: Pts were randomly assigned to receive SKB264 (n = 130) or chemotherapy (n = 133). The median age was 51 years; 87% had visceral metastases; 26% received prior PD-1/PD-L1 inhibitors; 48% received three or more prior lines of chemotherapy for advanced disease. The primary endpoint of PFS was met based on interim analysis (data cutoff: Jun 21, 2023) with a 69% reduction in risk of progression or death (HR 0.31; 95% CI, 0.22 to 0.45; P <0.00001). The median PFS assessed by BICR was 5.7 months (95% CI, 4.3 to 7.2) with SKB264 and 2.3 months (95% CI, 1.6 to 2.7) with chemotherapy; PFS at 6 months was 43.4% vs 11.1%. In the subset of pts with TROP2 H-score > 200, the median PFS was 5.8 months with SKB264 and 1.9 months with chemotherapy (HR 0.28; 95% CI, 0.17 to 0.48). At the first planned interim analysis for overall survival (OS) (data cutoff: Nov 30, 2023) with median follow-up of 10.4 months, OS was statistically significant in favor of SKB264 (HR 0.53; 95% CI, 0.36 to 0.78; P =0.0005); the median OS was not reached (95% CI, 11.2 to NE) with SKB264 and 9.4 months (95% CI, 8.5 to 11.7) with chemotherapy. The objective response rate assessed by BICR was 43.8% with SKB264 and 12.8% with chemotherapy. Most common grade ≥ 3 treatment-related adverse events (SKB264 vs chemotherapy) were neutrophil count decreased (32.3% vs 47.0%), anemia (27.7% vs 6.1%) and white blood cell count decreased (25.4% vs 36.4%). Conclusions: Sacituzumab tirumotecan monotherapy demonstrated statistically significant and clinically meaningful PFS and OS benefit over chemotherapy, with a manageable safety profile in pts with heavily pretreated advanced TNBC and limited treatment options. Clinical trial information: NCT05347134 .

Sacituzumab tirumotecan (SKB264/MK-2870) in combination with KL-A167 (anti-PD-L1) as first-line treatment for patients with advanced NSCLC from the phase II OptiTROP-Lung01 study.

8502 Background: Sacituzumab Tirumotecan (SKB264/MK-2870)is a TROP2 ADC developed with novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor. The hydrolytically linker permits both extracellular pH-sensitive cleavage and intracellular enzymatic cleavage to release the membrane permeable payload enabling the “bystander effect”. Here, we report the initial results from a phase II study of SKB264 combined with KL-A167 in patients (pts) with advanced NSCLC (OptiTROP-Lung01, NCT05351788). Methods: Pts with treatment naive advanced NSCLC without actionable genomic alterations were enrolled to receive SKB264 5 mg/kg Q3W + KL-A167 1200 mg Q3W (cohort 1A) or SKB264 5 mg/kg Q2W + KL-A167 900 mg Q2W (cohort 1B) in a non-randomized manner until disease progression or unacceptable toxicity. Tumor assessments based on RECIST 1.1 were performed every 6 weeks by investigators. Results: As of 02 Jan 2024, 40 and 63 pts have been enrolled in cohort 1A and 1B. Median ages were 63/63 years; 97.5%/85.7% had ECOG PS of 1; 30.0%/33.3%, 32.5%/30.2% and 37.5%/36.5% of pts had PD-L1 expression < 1%, 1%–49% and ≥ 50% of tumor cells by IHC 22C3 pharmDx assay, respectively. In cohorts 1A/1B, the most common Grade ≥ 3 treatment-related adverse events (TRAEs) were neutrophil count decreased (30.0%/30.2%), white blood cell count decreased (5.0%/17.5%), anemia (5.0%/15.9%), rash (5.0%/6.3%) and drug eruption (7.5%/0). TRAE leading to discontinuation of SKB264 occurred in 1 pt of cohort 1B due to drug hypersensitivity, and there were no treatment-related deaths. After median follow up of 14.0 mos and 6.9 mos for cohort 1A and 1B, the ORR was 48.6% (18/37, 2 pending confirmation), DCR was 94.6% and median PFS was 15.4 mos (95% CI: 6.7, NE) with 6-mo PFS rate of 69.2% for cohort 1A ; the ORR was 77.6% (45/58, 5 pending confirmation), DCR was 100% and median PFS was not reached with 6-mo PFS rate of 84.6% for cohort 1B. Additional subgroup analyses are shown in the Table. Conclusions: SKB264 in combination with KL-A167 demonstrated promising efficacy results in treatment naive advanced NSCLC with manageable safety profile. SKB264 Q2W was recommended for further investigation. A Phase 3 study of SKB264 Q2W plus pembrolizumab vs pembrolizumab in 1L metastatic NSCLC with PD-L1 TPS ≥ 50% (NCT06170788) is ongoing. Clinical trial information: NCT05351788 . [Table: see text]

First-in-human trial of M9140, an anti-CEACAM5 antibody drug conjugate (ADC) with exatecan payload, in patients (pts) with metastatic colorectal cancer (mCRC).

3000 Background: CEACAM5 is a cell surface protein with limited expression in adult healthy tissues, but high expression in various adenocarcinomas, particularly in CRC (>90% of pts). M9140 is the first anti-CEACAM5 ADC with a topoisomerase 1 inhibitor (Top1i) payload (exatecan). The ß-glucuronide linker connecting the M9140 antibody backbone to the payload is highly stable in circulation (drug-to-antibody ratio=8). In preclinical models, M9140 has demonstrated strong potency, antitumor activity, and a bystander effect. Methods: This Phase 1 trial (NCT05464030) investigated the safety, tolerability, pharmacokinetics (PK), and preliminary clinical activity of M9140 as monotherapy (Q3W [Day 1 of 21-day cycles]; IV) in adults with CRC (ECOG PS ≤1) who had received ≥2 prior lines of treatment. The primary objectives of Part 1A were to determine the maximum tolerated dose (MTD) and/or recommended dose(s) for expansion (RDE). Results: At data cutoff (19 Jan 2024), 40 pts from the US, EU, and Japan were treated across 7 dose levels (DLs): 0.6 mg/kg, 1.2 mg/kg (n=3, each), 2.4 mg/kg (n=7), 2.6 mg/kg (n=4), 2.8 mg/kg (n=12), 3.0 mg/kg (n=4), and 3.2 mg/kg (n=7, including 3 pts with primary G-CSF prophylaxis). Most pts were heavily pretreated (80% had ≥3 lines of prior treatment; 100% received irinotecan). Overall, 6 pts experienced dose-limiting toxicities (DLTs); the majority were hematological adverse events at DLs 3.0 and 3.2 mg/kg; 1 patient (at 2.8 mg/kg) experienced a Grade 5 sepsis. The most frequently reported Grade ≥3 treatment-emergent adverse events (TEAEs) were neutropenia in 16 (40.0%) pts, thrombocytopenia and anemia in 11 (27.5%) pts each, and WBC decreased in 10 (25.0%) pts. No events of ocular toxicity/interstitial lung disease (ILD) were reported. The best objective response per RECIST v1.1 was partial response (PR) in 4 (10.0%) pts (3 confirmed) (all at DLs ≥2.4 mg/kg); stable disease (SD) in 17 (42.5%), including 6 (15.0%) lasting for ≥100 days and progressive disease (PD) in 6 (15.0%) pts. For a total of 13 (32.5%) pts, the best overall response was not evaluable, including 6 (15.0%) who had no on-treatment tumor assessment yet. The preliminary median progression-free survival (PFS) was 6.7 months (95% CI: 4.6, 8.4). As of data cutoff, 15 (37.5%) pts are continuing treatment. Based on the safety, tolerability, preliminary clinical activity, PK, and PK/pharmacodynamics modeling data, 2.8 mg/kg was declared as the MTD, and 2.4 mg/kg and 2.8 mg/kg were chosen as the RDEs and have been taken forward into a randomized expansion study. Conclusions: M9140 demonstrated encouraging activity in heavily pretreated pts with advanced CRC, with a manageable and predictable safety profile. Contrary to approved ADCs with Top1i payloads, no ILD or ocular toxicities were observed. Evaluation of M9140 in mCRC continues in the dose expansion part of this study. Clinical trial information: NCT05464030 .

Preclinical studies of an innovative 5T4-ADC ACR246 with the potential to better treat 5T4-positive solid tumors.

e15005 Background: 5T4 oncofetal antigen shows limited expression in normal adult tissues but highly expressed by many different cancers. It drives spread of cancer cells through epithelial mesenchymal transition (EMT), potentiation of CXCL12/CXCR4 chemotaxis and favoring non-canonical Wnt pathway, leading to poor prognosis of cancer patients. Besides, 5T4 has a highly efficient endocytosis ability which enables it to be an ideal target for the development of ADC drugs. A handful of 5T4-targeted ADCs have been evaluated in early phase clinical trials for several years showing only preliminary anti-tumor activity. However, uncertainty of their safety profiles has also raised concerns due to high toxic payloads, MMAF and duocarmycin, being used. Thus, additional approaches to this target with the potential of improved efficacy and reduced toxicity are needed urgently. ACR246, an innovative 5T4-targeted ADC consisting of specific humanized monoclonal antibody site-specifically conjugated with a cell penetrating and moderate toxic payload (DNA topoisomerase I inhibitor, D2102) that has a robust bystander effect through a stable and cleavable linker, with a drug-to-antibody ratio (DAR) of 8, was designed to improve the safety and efficacy in treating tumor patients. Methods: The pharmacologic profiles of ACR246 were assessed in vitro and in vivo including efficacy, pharmacokinetics-pharmacodynamics (PK-PD), safety, and tissue distribution, in 5T4-positive cell lines, cell-derived xenograft (CDX) models and cynomolgus monkeys. Results: ACR246 bound specifically to 5T4 and was internalized into tumor cells followed by D2102 release, which induced DNA damage, cell cycle arrest and apoptosis in 5T4 positive tumor cells in vitro. In vivo low systemic exposure and tumor-specific accumulation of D2102 rendered ACR246 superior efficacy and safety property. Accordingly, ACR246 exhibited robust in vivo anti-tumor activity across various types of 5T4 positive CDX models in a dose-dependent manner, with DNA damage induced by the accumulated D2102 in tumor tissue. GLP toxicity studies indicated that ACR246 was well tolerated in cynomolgus monkeys. The estimated therapeutic index was 24. Conclusions: The overall preclinical profile marks ACR246 has the potential to become the best in class (BIC) 5T4-ADC, showing more favorable benefit-risk ratio in clinic.

Phase 1 study of BAT8006, a folate receptor α antibody drug conjugate with strong bystander effect, in subjects with advanced solid tumors.

Phase 1 study of BAT8006, a folate receptor α antibody drug conjugate with strong bystander effect, in subjects with advanced solid tumors.