Antitumor Effects Research Articles

HER2 expression-independent antitumor effect of trastuzumab deruxtecan (T-DXd) on pediatric solid tumors.

e15016 Background: Treatment of pediatric solid tumors shows limited improvement even with intensification of conventional chemotherapy, suggesting novel approaches such as targeted therapies are needed. Trastuzumab Deruxtecan (T-DXd), a HER2-targeting antibody–drug conjugate, exhibits significant anti-cancer activity in breast cancers with a broad range of HER2 expression. T-DXd might be a promising agent for refractory or relapsed pediatric solid tumors, but its efficacy in pediatric tumors needs to be studied. Methods: Anti-cancer efficacy of T-DXd and its payload DXd were assessed in vitro by utilizing our in-house cancer cell line models. Cytotoxicity assays were performed for 60 pediatric cancer cell lines, including Neuroblastoma (NB) = 25, Ewing sarcoma / Ewing sarcoma family of tumors (EWS / EWSFT) = 17, Rhabdomyosarcoma (RMS) = 10, Others (Osteosarcoma, Brain tumor, Wilms tumor, Hepatoblastoma, and Malignant rhabdoid tumor (MRT) = 8, and 2 breast cancer cell lines expressing HER2 high or low (IHC score 2+ or 0) as positive or low control, respectively. We analyzed HER2 expression on the cell surface by flow cytometry and evaluated relative mean fluorescence intensity (MFI) values. Results: In the flow cytometric assessment, pediatric cancer cell lines showed smaller median MFI of 1.40 (0.67 - 2.71) compared with breast cancer control with HER2 high expression (33.77). The median MFI of each cell lines were 0.94 in NB, 1.76 in EWS / EWSFT, 1.42 in RMS, 1.52 in other pediatric cancers. Although low or no expression of HER2, certain inhibitory activities to the cell growth were observed for T-DXd against a part of NB, EWS, RMS and MRT cell lines, with the minimum IC50 values of 14.5 nM, 6.5 nM, 10.2 nM, 8.1 nM, respectively. In NB, EWS and RMS, a wide range of sensitivity to T-DXd were seen among different cell lines in the same disease. Most of cell lines showed high sensitivity to DXd (Median IC50 value: 0.90 nM [0.08 - 6.46 nM]), but, among them, cell lines with lower sensitivity to DXd tend to show less sensitivity to T-DXd. There was no clear correlation between sensitivity to T-DXd and HER2 expression among pediatric cancer cell lines, indicating that other mechanism such as intrinsic sensitivity to payload might affect antitumor activity of T-DXd. Conclusions: T-DXd exhibited antitumor efficacy against pediatric solid tumors in vitro irrespective of HER2 expression. Our results suggest that T-DXd might be an alternative therapy for pediatric solid tumor cases for whom conventional chemotherapies and other targeting therapies are ineffective. This study supports further investigation for T-DXd in this population.

Fruquintinib combined with sintilimab and SOX as conversion therapy for unresectable locally advanced or metastatic gastric/gastroesophageal junction adenocarcinoma (GC/GEJC): A single-arm, open-label, phase 2 clinical trial.

e16021 Background: The evidence of conversion therapy for unresectable GC/GEJC is limited. Fruquintinib is an oral, highly selective VEGFR 1/2/3 inhibitor that has synergistic antitumor effects when combined with ICIs/chemotherapy. This study was conducted to evaluate the efficacy and safety of fruquintinib combined with sintilimab and SOX as a conversion therapy in patients (pts) with initially unresectable locally advanced or metastatic GC/GEJC. Methods: Eligible pts received 3 to 6 cycles of fruquintinib (4mg/d, po, qd, d1-14) combined with sintilimab (200mg, iv, d1), oxaliplatin (130 mg/m2, iv, d1) and S-1 (40-60mg based on BSA, po, bid, d1-14) every 3 weeks. One more cycle of sintilimab plus SOX was given before resection. Radiographic assessments were performed every 3 cycles and MDTs were employed to determine surgical feasibility. Primary endpoint was R0 resection rate. Secondary endpoints included pathological response, ORR, PFS, OS, and safety. Results: From May 2022 to December 2023, 34 pts (29 males/5 females) with a median age of 62 years (range: 43–76), 71% ECOG PS1, 59% GEJC were enrolled. The unresectable factors included liver metastasis 15% (5/34), peritoneal metastasis 6% (2/34), para-aortic lymph node metastasis 3% (1/34), extensive or bulky lymph nodes 53% (18/34), and local progression 38% (13/34). Five pts had more than one unresectable factors. The ORR and DCR of 29 pts who had at least one preoperative assessment were 65.5% (19 PR) and 96.6%, respectively. Among the 18 pts who had completed surgical conversion, all of them had R0 resection (100%), 2 pts (11.1%) achieved pathological complete response (pCR), and 1 pt reached AJCC-TRG1. The pathological response rate (pRR) according to JCGC (≥ Grade 1b) was 100% (18/18). Additionally, downstaging to pN0 was achieved in 13 pts (72.2%). During preoperative treatment, treatment-emergent adverse events (TEAEs) occurred in 85.3% (29/34) pts, and most events were grade 1–2. Grade 3 TEAEs included 2 cases of neutrophil count decreased, and 1 case of each (platelet count decreased, anemia, diarrhea, and immune-related pneumonitis). No severe surgery-related complication was observed. Conclusions: Fruquintinib combined with sintilimab and SOX as a conversion therapy strategy shown acceptable toxicity in unresectable GC/GEJC and induced very high R0 resection, pathological response, and downstaging rate. The study is ongoing, more data will be disclosed in the future. Clinical trial information: NCT05177068 .

Reactive oxygen species produced by photodynamic therapy enhance docosahexaenoic acid lipid peroxidation and induce the death of breast cancer cells

Breast cancer remains a serious threat to women's physical and emotional health. The combination therapies can overcome the deficiency of single therapy, enhance the therapeutic effects and reduce the side effects at the same time. In this study, we synthesize a novel nanomedicine that enhanced the therapeutic effects of breast cancer treatment by combining photodynamic therapy and chemotherapy. The doxorubicin (DOX) and photosensitizer methyl pyropheophorbide-a (MPPa) are loaded into the nano-drug delivery system as DPSPFA/MPPa/DOX. In response to near-infrared (NIR) laser, the drugs were quickly released to the cancer cells. The MPPa produces reactive oxygen species (ROS) under the action of photodynamics. Unsaturated fatty acids with ROS promotes lipid peroxidation and the combination of chemotherapy and photodynamic therapy. The data shows that the DPSPFA/MPPa/DOX has a spherical shape, good dispersibility and stability, and the particle size is roughly 200 nm. The drug loading capability of DOX is about 13 %. Both of MCF7 cell model in vitro and breast cancer model in vivo, DPSPFA/MPPa/DOX showed an excellent anti-tumor effect of 86.9 % and without any obvious side effects. These findings might offer potential for a new approach for breast cancer treatment.

Reduced Tumor Volume and Increased Necrosis of Human Breast Tumor Xenograft in Mice Pretreated by a Cocktail of Three Specific Anti-HER2 scFvs.

We aimed to assess the effects of a cocktail comprising three specific anti- HER2 scFvs on breast tumor formation in a xenograft mouse model and to evaluate quantitative changes in the tumor using stereological analysis. Three specific anti-HER2 phage antibodies were produced from a scFv-library using phage display technology. The cell binding capacities of the antibodies were assessed via FACS analysis. Soluble forms of the antibodies were prepared by infecting HB2151-E. coli cells and purified using a centrifugal ultrafiltration method. The purification process was evaluated by SDSPAGE analysis. Two forms of scFv cocktails were prepared, soluble scFv and phage-scFv cocktail, which contained an equal amount/phage of each of the three antibodies. Inbred female BALB/c mice were pretreated with 5 and 20 mg/kg of the soluble scFv cocktail and 1011 phage-scFv cocktail/ kg. The mice were then injected with 2×106 SKBR-3 human breast cancer cells. Total tumor, inflammatory and non-inflammatory volumes were estimated using the Cavalieri principle after preparing photomicrograph slides. The anti-HER2 scFvs showed significantly higher binding to SKBR-3 cells compared to the isotype control. SDS-PAGE analysis confirmed the high purification of the scFvs. Stereological analysis revealed that the group pretreated with 20 mg/kg of the soluble scFv cocktail exhibited the highest reductions in total tumor volume, non-inflammatory volume, and inflammatory volume, with reductions of 73%, 78%, and 72%, respectively, compared to PBS-pretreated mice (P-value < 0.0001). The volumetric ratio of necrotic tissue to total tumor volume increased by 2.2-fold and 2- fold in the 20 mg/kg of soluble scFv cocktail and phage-scFv cocktail groups, respectively, compared to the PBS-treated mice (P-value < 0.05). Pre-treatment with a 20 mg/kg anti-HER2 scFv cocktail resulted in a significant reduction in tumor volume and increased necrotic area in a human breast cancer xenograft model, indicating the remarkable anti-tumor effect of the cocktail in vivo.

Hederagenin Induces Apoptosis of Human Hepatoma HepG2 Cells via the Mitochondrial Pathway.

The objective of this study is to assess the antitumor effects of hederagenin (HDG) in liver cancer (LC) cells and explore the related mechanisms. HepG2 cells were treated with HDG and cisplatin, respectively. The CCK8 assay was used to detect cell activity, DAPI staining was used to detect the proportion of living cells, TUNEL assay to detect the proportion of apoptotic cells, flow cytometry to detect the membrane potential, fluoroscopic electron microscopy to detect microstructural changes to the mitochondrial, and western blot analysis and high-content screening to detect apoptosisrelated proteins. Treatment with HDG inhibited the growth of HepG2 cells, decreased the proportion of viable cells, increased the proportion of apoptotic cells, and significantly increased the proportion of cells in the G1 phase. Fluorescence staining showed that HDG damaged the mitochondria of HepG2 cells and significantly decreased the number of mitochondria. Flow cytometry showed that HDG decreased the mitochondrial membrane potential of HepG2 cells. Observations by electron microscopy showed that HDG caused swelling and vacuole formation of the mitochondria of HepG2 cells. HDG significantly reduced the average fluorescence intensity of Bcl-2 in HepG2 cells and significantly increased that of the pro-apoptosis proteins Bax, Cytochrome-c, and Caspase-3. HDG induced apoptosis of HepG2 cells via the mitochondrial pathway.

Neoadjuvant cadonilimab (PD-1/CTLA-4 bispecific antibody) plus FLOT chemotherapy in locally advanced gastric/gastroesophageal junction cancer (GC/GEJC): A prospective, multi-center, phase II study.

e16108 Background: FLOT remains the preferred neoadjuvant treatment (NAT) for locally advanced GC/GEJC, with evidence suggesting enhanced efficacy when plus PD-1 inhibitors. Cadonilimab, a bispecific antibody targeting PD-1 and CTLA-4, also exhibited survival benefits when combined with chemotherapy as first-line treatment for GC/GEJC. This study aimed to assess the efficacy and safety of Cadonilimab and FLOT as NAT in locally advanced GC/GEJC. Methods: Pathologically confirmed treatment-naïve patients (pts), aged 18-75, with radiologically evaluable primary GC/GEJC at stage cT3/4, ECOG PS 0-1, were enrolled. The study used simon-2 stage design with a total sample size of 38 pts and would be considered effective if more than 4 pts achieved pCR. Pts received surgery after completing NAT with Cadonilimab (10mg/kg, iv, Q3W) and FLOT (50mg/m² docetaxel, 85mg/m² oxaliplatin, 2600mg/m² 5-FU, and 200mg/m² leucovorin, iv). The primary endpoints were pCR and MPR rate. Secondary endpoints included ORR, DCR, R0 resection rate and safety (CTCAE 5.0). Results: In this phase II trial, initially enrolled 29 pts in stage I, with an additional 9 pts in stage II. Of the 34-evaluable pts, 30 pts underwent surgery. The median age was 57 years (range, 38-74), with 88.2% male and 64.7% diagnosed as stage cT4. According to RECIST1.1 criteria, 5 pts (14.7%) achieved CR, and 21pts (61.8%) achieved PR, with an ORR of 76.5% and DCR of 100.0%. According to Becker criteria for Tumor Regression Grade: 6 pts (20.0%) achieved TRG1a, 9 pts (30.0%) reached TRG1b, with a pCR rate of 20.0% and MPR rate of 50.0%. Pts with diffused and poorly differentiated tumors had higher rates of pCR and MPR (36.4%, 81.8%) than the overall population. A notable tumor downstaging was observed: 86.7% in T stage, 70.0% in N stage, and 70.0 in overall TNM stage. During the NAT phase, all 34 pts experienced TRAEs. Mild to moderate TRAEs (grade 1-2) were observed in 73.5% (25 patients), while 26.5% (9 patients) experienced grade 3 TRAEs. There were no reports of grade 4-5 or severe TRAEs. The most common TRAEs were nausea (100.0%), alopecia (97.1%), vomiting (85.3%), fatigue (85.3%), electrolyte disturbance (79.4%) and rash (73.5%). In post-surgery, all 30 pts achieved R0 resection. Surgical complications were relatively minor, predominantly fever (46.7%), ascites (30.0%) and pneumonia (23.3%). The survival benefit will be reported after the follow-up completed. Conclusions: Neoadjuvant Cadonilimab plus FLOT chemotherapy exhibit encouraging anti-tumor effectiveness and manageable toxicities, particularly in pts with diffused Lauren`s classification and poorly differentiation. This immunochemotherapy regimen might provide a promising alternative NAT option for locally advanced GC/GEJC. Clinical trial information: ChiCTR2200066893.

Effect of a novel anti-PD-1-proIL-2 bifunctional fusion protein on potent anti-tumor activity via PD-1 checkpoint inhibition and conditional IL-2R agonism.

e14697 Background: HD IL-2 was approved by FDA for metastatic melanoma (mM) and renal cell carcinoma (mRCC) but the treatment is associated with severe toxicities. PD-1 blockade has improved the overall survival, but only in 20-30% of cancer patients and many of them experience frequent relapses. Interestingly, HD IL-2 therapy displayed durable anti-tumor activity in mM and mRCC patients who progressed on anti-PD-1. Furthermore, combination therapy of IL-2 and pembrolizumab in mRCC has shown durable 70% response rate, while the ORR of monotherapy is 20% and 33% for IL-2 and pembrolizumab, respectively. Thus, combining IL-2 receptor activation and PD-1 blockade may represent a promising strategy in the post PD-1 era to overcome the resistance and improve the clinical efficacy. PTX-912 is a novel bifunctional PD-1-proIL-2v fusion protein designed to simultaneously harness PD-1 blockade and PD-1-cis directed IL-2R agonism conditionally in TME without the peripheral toxicities associated with IL-2. Methods: The biological functions were demonstrated in human PBMC assays. Anti-tumor efficacy and biomarker studies were evaluated in mouse / human PBMC xenograft models. Tox studies were performed in NHP. Results: PTX-912 shows dose-dependent inhibition of PD-1 pathway measured by GM-CSF and IFNgamma production in an MLR assay. Protease activated PTX-912, but not the intact drug, stimulates the phosphorylation of STAT5 of NK and T cells, the proliferation of CD8 T cells as well as the cytokine production in human whole blood. The potency of pSTAT5 by protease activated product is enhanced by &gt; 10 folds on PD-1+ T cells than T cells without PD-1. When tested in mouse tumor models resistant to PD-1 blockade, PTX-912 demonstrated high potency of tumor inhibition at as low as 0.1 mg/kg dose. In contrast, non-targeted proIL-2v at molar equivalent or higher dose showed minimal antitumor effect in either monotherapy or combination with anti-PD-1. Analysis of PTX-912 treated mice showed increased tumor infiltrating CD4+ and CD8+ T cells, including PD-1+Tcf-1+ and PD-1+ IL-18Ra+TIM3- CD8+ T cells, referred to “stem-like” progenitor effector cells and “better” effector cells, respectively. Activation of the IL-2v in PTX-912 was observed in mouse tumor tissues but not in the plasma. In monkey GLP-compliant 4-week repeat-dose toxicity study, PTX-912 demonstrated excellent safety profiles without overt irAEs that are characteristic of IL-2. Conclusions: Our preclinical data demonstrated that PTX-912 effectively stimulated the expansion and reinvigoration of antigen specific T cells in the tumor tissue resulting in strong anti-tumor efficacy while it did not cause significant peripheral toxicity. Phase 1 clinical trial of PD-1-proIL-2v is planned to start in early 2024 to evaluate the safety, pharmacokinetics and anti-tumor activity in patients with advanced solid tumors.

BY101921: Restoring interferon signaling and anti-tumor immunity through PARP7 inhibition.

3123 Background: PARP7( TIPARP), a member of monoPARP family, catalyzes ADP-ribose transfer to specific amino acids within itself and other substrate proteins, utilizing nicotinamide adenine dinucleotide (NAD+) as substrate. It plays a vital role in various biological processes such as gene expression, protein degradation, and cellular stress response. PARP7 amplification has been observed in various cancers, including squamous cell carcinoma, ovarian cancer, breast cancer, and pancreatic ductal adenocarcinoma. Over expression of PARP7 correlates with reduced survival in squamous cell carcinoma. PARP7's MARylation of α-tubulin induces microtubule instability, promoting proliferation and migration of ovarian cancer cells. As a negative regulator of tumor cell nucleic acid sensing, PARP7 inhibits TBK1 through. This, in turn, hampers the cGAS-STING signal pathway and downregulates the type Ⅰ interferon expression. BY101921, developed by Chengdu Baiyu Pharmaceutical, is a highly selective PARP7 inhibitor demonstrating significant anti-tumor effect in vitro and in vivo, both alone and in combination with anti-PD-1. Methods: Enzymatic evaluation was conducted on BY101921 to assess its selectivity among major PARP family members. PK studies were investigated in both mouse and dog species. The anti-tumor activity of BY101921, both as a monotherapy and in combo with anti-PD-1, was investigated in NCI-H1373 and CT26 tumor-bearing mice, respectively. In terms of anti-tumor mechanism, pSTAT1, IFN-β and CXCL10 levels were analyzed in RAW264.7 cells and CT26 tumor-bearing tissues. In addition, the effect of BY101921 on the type Ⅰ interferon signaling pathway was systematically evaluated. Results: BY101921 demonstrated outstanding selectivity as a PARP7 inhibitor, displaying limited off-target effects on PARP1/2, reducing the risk of systemic toxicity, especially hematologic effects. In mice and dogs, BY101921 revealed favorable PK characteristics following oral administration. In vivo, BY101921 exhibited potent inhibition of tumor growth as a monotherapy, and its combination with anti-PD-1 further enhanced its anti-tumor efficacy, with excellent tolerability in animals. Mechanism of action studies showed that BY101921 generated an anti-tumor immune response by upregulating pSTAT1 levels and promoting the secretion of IFN-β and CXCL10, thereby restoring the type Ⅰ interferon signaling pathway. Conclusions: BY101921, a potent and selective PARP7 inhibitor, demonstrates significant anti-tumor efficacy both as a monotherapy and in combo with anti-PD-1, while maintaining excellent tolerability in animal models. With favorable drug-like properties and a promising safety profile, BY101921 holds potential as an enhanced therapeutic option for cancer patients. At present, clinical studies investigating BY101921 as a single agent and in combo with anti-PD-1 are in the recruitment phase.

Cardiotoxicity of immune checkpoint inhibitors: A retrospective cohort study of 93,362 patients.

e14529 Background: The advent of immune checkpoint inhibitors (ICI) as therapy for a wide array of cancer types has extended patient survival and propelled the field of oncology into a new era. However, notable immune-related adverse events have been observed that transgress self-tolerance. Among these adverse events, myocarditis is emerging as a serious and often lethal toxicity. This study aims to assess whether a significant association exists between immune checkpoint inhibitors and myocarditis and/or pericarditis. Methods: The TriNetX research network was used for this study. Two patient cohorts were created by using International Classification of Disease 10 (ICD-10) codes and HCPCS codes. Both patient cohorts consisted of patients with malignancy (C00-D49) and no history of myocarditis. One cohort was treated with immunotherapy while the other was excluded from such exposure (HCPCS codes were used for ipilimumab, nivolumab, pembrolizumab, and durvalumab). The cohorts were balanced for age, race, gender, and ethnicity by propensity score matching and the greedy nearest neighbor algorithm, resulting in 46,681 patients in each arm. They were then evaluated for the development of myocarditis or pericarditis (I51.4, I31, I30) over the subsequent 5 years. Results: Cancer patients treated with immunotherapy were significantly more likely to experience myocarditis or pericarditis than those who did not receive those agents (7% vs 1.2%, RR 5.8, 95% CI (5.33,6.36), P value &lt;0.0001). Conclusions: This study suggests a significant association between the use of immunotherapy agents and the development of myocarditis and pericarditis. Further studies are necessary to better delineate the mechanism by which these cardiac toxicities occur, establish guidelines for surveillance of its onset, and discover how to suppress the immune-toxicities while retaining anti-tumor effect.

Tabersonine Induces the Apoptosis of Human Hepatocellular Carcinoma In vitro and In vivo.

Tabersonine, a natural indole alkaloid derived from Apocynaceae plants, exhibits antiinflammatory and acetylcholinesterase inhibitory activities, among other pharmacological effects. However, its anti-tumor properties and the underlying molecular mechanisms remain underexplored. The present study aims to investigate the anti-tumor effects of tabersonine and its mechanisms in inducing apoptosis in hepatocellular carcinoma. The inhibitory effects of tabersonine on the viability and proliferation of liver cancer cells were evaluated using MTT assay and colony formation assay. AO/EB, Hoechst, and Annexin V-FITC/ PI staining techniques were employed to observe cell damage and apoptosis. JC-1 staining was used to detect changes in mitochondrial membrane potential. Western blot analysis was conducted to study the anti-tumor mechanism of tabersonine on liver cancer cells. Additionally, a xenograft model using mice hepatoma HepG2 cells was established to assess the anti-tumor potency of tabersonine in vivo. Our findings revealed that tabersonine significantly inhibited cell viability and proliferation, inducing apoptosis in liver cancer cells. Treatment with tabersonine inhibited Akt phosphorylation, reduced mitochondrial membrane potential, promoted cytochrome c release from mitochondria to the cytoplasm, and increased the ratio of Bax to Bcl-2. These findings suggested that tabersonine induces apoptosis in liver cancer cells through the mitochondrial pathway. Furthermore, tabersonine treatment activated the death receptor pathway of apoptosis. In vivo studies demonstrated that tabersonine significantly inhibited xenograft tumor growth. Our study is the first to demonstrate that tabersonine induces apoptosis in HepG2 cells through both mitochondrial and death receptor apoptotic pathways, suggesting its potential as a therapeutic agent candidate for hepatic cancer.

Tislelizumab combined with chemotherapy in advanced thymic tumors.

e20139 Background: Thymic tumors refer to tumors derived from thymic epithelial cells, including thymoma and thymic carcinoma. Most cases in advanced stages when detected, and treatment is still controversial. Since 2018, immunotherapy has gradually been used for a variety of solid tumors and the curative efficacy has been notable. The efficacy of immunotherapy is increasingly improved with the increased expression of programmed death-ligand 1 (PD-L1) by tumor cells. The thymus is an immune-rich organ. PD-L1 expression ranges from 23% to 92% in thymoma, and from 36% to 100% in thymic carcinoma. Thus, immunotherapy has been implicated as having broad prospects in the treatment of thymic tumors. Tislelizumab is an inhibitor of PD-1, which has shown preliminary anti-tumor effects in various solid tumors. The combination of immunotherapy and chemotherapy has produced excellent anti-tumor activity for various types of tumors. However, there is a lack of clinical trial data to support the application of tislelizumab for the treatment of advanced thymic tumors. In this article, the efficacy and safety of tislelizumab combined with chemotherapy were analyzed in eight patients with advanced thymic tumors to provide data for the use of this monoclonal antibody as first-line treatment of advanced thymic tumors. Methods: Here, after obtaining fully informed consent, we report cases involving eight patients with advanced thymic tumors treated with tislelizumab combined with chemotherapy. The clinical characteristics, lesion changes, treatment process, drugs used, drug efficacy, complications or adverse reactions were recorded and followed up to evaluate the efficacy and safety of tislelizumab combined with chemotherapy in the treatment of advanced thymic tumors. Results: This article reports eight cases of advanced thymic tumor treated with tislelizumab combined with chemotherapy. Two patients received tislelizumab combined with chemotherapy as first-line treatment, and the remaining six patients were treated with tislelizumab after poor response to chemotherapy. Five patients achieved a partial response to the combined treatment. Of these, the partial response was retained in three patients after switching to tislelizumab monotherapy. The remaining three patients displayed stable disease after the combined treatment. There were no serious immune-related adverse events during treatment. The side effects of tislelizumab combined with chemotherapy were well tolerated. Conclusions: No clinical study of immunotherapy combined with standard chemotherapy as first-line treatment for advanced unresectable or metastatic thymic epithelial tumors has been described. This article provides strong evidence for the early application or even first-line use of tislelizumab combined with chemotherapy for advanced thymic epithelial tumors. More clinical studies are needed to evaluate the efficacy and safety of tislelizumab in thymic tumors.

Preclinical assessment of combined BCL-2 and MCL-1 inhibition in high-risk neuroblastoma

BackgroundNeuroblastoma is the most common extracranial pediatric solid malignancy with high-risk patients showing survival rates less than 50 %. These tumors frequently escape apoptosis through upregulation of the anti-apoptotic protein BCL-2. Unfortunately, monotherapy with the BCL-2 inhibitor venetoclax leads to therapy-induced resistance mediated by upregulation of MCL-1, thereby indicating that tumors could be responsive to dual inhibition of BCL-2 and MCL-1. MethodsIn vitro efficacy of venetoclax and multiple MCL-1 inhibitors (MIK665, S63845, AMG-176, AZD-5991) was studied in neuroblastoma cell lines with BCL-2 and/or MCL-1 dependency. Synergy assays were performed to identify the MCL-1 inhibitor with best performance in combination with venetoclax, followed by examining if dual BCL-2 and MCL-1 inhibition protects against resistance. Lastly, the combination was analyzed in two patient-derived xenograft (PDX) models. ResultsVenetoclax showed highest efficacy in neuroblastoma cell lines with high BCL-2 mRNA expression, BCL-2 protein levels or BIM:BCL-2 complex formation, while MCL-1 inhibitor efficacy was best correlated with BIM:MCL-1 complex levels. Most promising anti-tumor effects were observed following combination therapy with venetoclax and MIK665. Targeting BCL-2 and MCL-1 led to strong synergy and efficacy at low concentrations, induced apoptosis and prevented resistance. PDX validation studies combining venetoclax with MIK665 showed improved responses compared to monotherapies. ConclusionDual inhibition of BCL-2 and MCL-1 in neuroblastoma cells showed highly efficacious and synergistic responses in vitro, but only led to mild additive effects in vivo. Hence, better understanding of in vivo efficacy and side effects of this combination treatment are warranted prior to clinical translation.

Efficacy and safety of neoadjuvant chemoradiotherapy combined with tislelizumab and thymalfasin in the treatment of locally advanced lower rectal cancer.

e15612 Background: Thymalfasin, as an immunomodulator, can enhance the anti-tumor effects of T cells, NK cells, and macrophages. This study explored the efficacy and safety of a new adjuvant treatment regimen for rectal cancer, combining thymalfasin with chemoradiotherapy and the PD-1 inhibitor tislelizumab, and its impact on the immune microenvironment. Methods: This retrospective study enrolled 26 patients with locally advanced rectal cancer from March 2021 to December 2022. Thirteen patients received long-course concurrent chemoradiotherapy combined with concurrent tislelizumab treatment, and thirteen received thymalfasin combined with long-course chemoradiotherapy and concurrent tislelizumab treatment (radiotherapy: 50 Gy/25 f; capecitabine, 1000mg/m2, bid; tislelizumab: 200mg, every 21 days, 3 cycles; Thymalfasin: 1.6mg, biw). The postoperative pathological complete response rate (ypT0N0M0), tumor regression grade (AJCC 8th Version), and adverse event (CTCAE 4.0) incidence were assessed, along with changes in the immune microenvironment before and after treatment using multiplex immunofluorescence staining. Results: The pathological complete response rates observed postoperatively were 61.5% in the treatment group, compared to 38.5% in the control group. The distribution of tumor regression grades 0, 1, 2, and 3 was 69.2%, 15.4%, 15.4%, 0% in the treatment group respectively, and 38.5%, 38.5%, 7.7%, 15.4%, in the control group respectively. The adverse event rates reached 84.6% in the treatment group and 76.9% in the control group, with all events classified as either grade 1 or 2 according to the CTCAE 4.0. Significant reductions in CD4+PD1+ cell density (p &lt; 0.001), CD8+PD1+ cell density (p = 0.024), CD68+ cell density (p = 0.007), the CD4/CD8 ratio (p &lt; 0.001), and the CD68+CD86+/CD68+CD163+ ratio (p = 0.012) were demonstrated through multiplex immunofluorescence following neoadjuvant treatment. The treatment group exhibited significant decreases in CD8+PD1+ cell density (p = 0.025) and CD68+CD163+ cell density (p = 0.021) when compared to the control group. Conclusions: Thymalfasin combined with chemoradiotherapy and tislelizumab as a neoadjuvant treatment regimen for patients with locally advanced lower rectal cancer has shown favorable efficacy and safety. Neoadjuvant chemoradiotherapy combined with immunotherapy restored T cell function and reduced the proportion of tumor-associated macrophages, but macrophages polarized towards an M2-like phenotype. Thymalfasin may play a role by synergizing with the PD-1 inhibitor to restore cytotoxic T cell function and block macrophage polarization towards M2 cells. Clinical trial information: NCT06024356 .

Phase Ib study of a high potent PI3K-mTOR dual inhibitor WX390 combined with toripalimab in patients with advanced solid tumors.

e14627 Background: WX390 is a high potent PI3K-mTOR dual inhibitor targeting pan-PI3K and mTOR. It modulates the tumor immune microenvironment by decreasing tumor Treg and myeloid-derived suppressor cells (MDSC) and improves the immune response to checkpoint inhibitors (CPI) in preclinical models. Methods: The Phase Ib study was designed to evaluate safety, pharmacokinetics (PK), and preliminary clinical activity, to determine recommended phase 2 dose (RP2D) of WX390 combined with Toripalimab in patients with advanced solid tumors. WX390 was administered orally daily at escalating doses of 0.7 mg, 0.9mg and 1.1mg, with Toripalimab at 240 mg IV every 3 weeks until confirmed progressive disease, intolerable toxicity or withdrawal of consent. Plasma PK samples were collected up to 24 hours after the first dose at C1D1, and up to 24 hours before and after the morning dose at C1D21. Results: As of December 31, 2023, total 18 patients had been treated in 3 WX390 cohorts: 0.7 mg (n = 3), 0.9 mg (n = 3), and 1.1 mg (n = 12) once daily (QD). No dose limit toxicity (DLT) was observed, and the RP2D of WX390 in combination was 1.1 mg QD, which was consistent with the single agent RP2D. The treatment related adverse events (TRAEs) (≥20%) included hyperglycemia (17/18, 94.4%), creatinine increased (12/18, 66.7%), weight loss (10/18, 55.6%), diarrhea (9/18, 50%), proteinuria (9/18, 50%), nausea (7/18, 38.9%), lymphocytopenia (7/18, 38.9%), vomiting (7/18, 38.9%), rash (7/18, 38.9%), decreased appetite (6/18, 33.3%), hypokalemia (6/18, 33%), fatigue (5/18, 27.8%), hyponatremia (4/18, 22.2%), and thrombocytopenia (4/18, 22.2%). Grade 3 TRAEs included hyperglycemia (5/18), lymphocytopenia (4/18), rash (2/18), weight loss (2/18), leukopenia (1/18), infusion-related reaction (1/18), nausea (1/18), and stomatitis (1/18). There was no TRAE leading to treatment permanent discontinuation and no grade 4/5 TRAE were observed. PK of WX390 in combination showed similar PK profile with the single agent. Among the 16 efficacy-evaluable patients with cervical (N=8), head and neck (N=5), and urothelial cancer (N=3), 5 patients (31.3%) previously received immune checkpoint inhibitors. 3 of 5 (60%) cervical cancer patients at RP2D and 2 of 5 head and neck cancer patient (40%) have achieved confirmed partial response (PR). In addition, 3 cervical patients who were treated with 0.7 or 0.9mg QD and 1of 3 urothelial carcer patients experienced tumor shrinkage (SD). The medium progression free survival (PFS) was 5.49 months (95% CI: 2.53, 6.37). Conclusions: WX390 in combination with Toripalimab had a manageable safety profile and encouraging antitumor effects in patients with advanced solid tumors. An RP2D of 1.1 mg qd of WX390 in combination was selected to be explored in further phase II study, which is ongoing in different tumor types. Clinical trial information: NCT06117566 .

Design, synthesis and biological evaluation of indoline-maleimide conjugates as potential antitumor agents for the treatment of colorectal cancer

An efficient protocol for direct coupling of maleimides and indolines at the C7-position was achieved under Rh(III) catalysis. Thirty four novel indoline-maleimide conjugates were prepared in good to excellent yields using this method. All compounds were evaluated for their anti-proliferative effect against colorectal cell lines. Among them, compound 3ab showed the most potent anti-proliferative activity against the CRC cells, and displayed low toxicity in the normal cell. Further investigation indicated that 3ab could effectively suppress the proliferation and migration of CRC cells, along with inducing cell cycle arrest and apoptosis. Mechanistic studies revealed that compound 3ab inhibited the proliferation of CRC cells via suppressing the AKT/GSK-3β pathway. In vivo evaluation demonstrated remarkable antitumor effect of 3ab (10 mg/kg) in the HCT116 xenograft model with no obvious toxicity, which is superior to that of 5-Fluorouracil (20 mg/kg). Therefore, conjugate 3ab could be considered as a potential CRC therapy agent for further development.

Enhancing the efficacy of anti-PD-L1 therapy by cabozantinib in the treatment of advanced esophageal squamous cell carcinoma (ESCC): Rationales from a preclinical study.

e16036 Background: Anti-PD-1/PD-L1 therapy has changed the therapeutic landscape of ESCC. However, the efficacy of anti-PD-1 therapy alone remains modest. Cabozantinib, a multikinase inhibitor with immune modulatory effect in preclinical studies, in combination with atezolizumab has been investigated in various cancer types. We conducted a preclinical study to investigate the efficacy of cabozantinib plus anti-PD-L1 therapy using immunocompetent mouse ESCC models. Methods: From esophageal tumors developed in C57BL/6 mice following chronic exposure to 4-nitroquinoline 1-oxide, we generated several ESCC clones, which could be successfully propagated by in vitro culture for more than 25 passages. The viability of mouse ESCC clones in in vitro cell culture treated with various concentrations of cabozantinib (Adooq Bioscience LLC, Irvine, CA, US) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. We used a subcutaneous mouse model by implanting 5 x 106 murine ESCC cells (clone 104) in male 5-week-old C57BL/6 mice to evaluate the in vivo therapeutic efficacy of anti-PD-L1 therapy (10F.9G2 clone [a rat anti-mouse PD-L1 antibody], Bio X Cell, Lebanon, NH, US) by intraperitoneal (ip) injection, cabozantinib by oral gavage, or the combination of both agents. Tumor volumes were measured twice per week using bilateral calipers. Following two weeks of treatment and an additional week of observation, all mice were sacrificed for tumor harvest. Tumor weights were determined and compared among different treatment groups. Results: Cabozantinib, up to 30 μM, induced only mild growth suppression (13.8 to 26.6%) of 3 mouse ESCC cell clones (clones 001, 103, and 104) in vitro. In the sc tumor model implanted with mouse ESCC clone 104, the anti-PD-L1 monotherapy (10mg/kg, twice per week) did not affect the tumor growth ( P = 0.2000), suggesting that the sc tumor of clone 104 is an anti-PD-L1 primary resistant model. On the contrary, cabozantinib (10 to 30 mg/kg/day, 5 days per week, for 2 weeks) induced a dose-dependent inhibition of tumor growth (tumor weight decreasing from 22.7 to 84.4%) in the sc tumor model of clone 104. The combination of anti-PD-L1 plus cabozantinib induced a more significant suppression of tumor growth than either single treatment alone, and cabozantinib at the dose of 20 mg/kg exhibited more pronounced enhancing effect than at the dose of 10 mg/kg. Conclusions: This preclinical study demonstrated a synergistic antitumor effect of combining anti-PD-L1 therapy with cabozantinib in immunocompetent murine models of ESCC. A phase II trial is ongoing to investigate the efficacy of cabozantinib plus atezolizumab in advanced ESCC (NCT05007613) (This work was supported by NTUCCS-112-06, NSTC112-2314-B-002-150-, NSTC112-2314-B-002-268-, MOHW111-TDU-B-221-114006, and MOHW112-TDU-B-221-124006).

Real-world Treatment Sequencing and Outcomes With Cabozantinib After First-line Immune Checkpoint Inhibitor-based Combination Therapy For Patients With Advanced Renal Cell Carcinoma: CARINA Study Results

IntroductionReal-world data are limited on treatment sequencing and outcomes after first-line (1L) immune checkpoint inhibitor (CPI)-based combination treatment of advanced renal cell carcinoma (aRCC). Patients and MethodsIn this real-world, UK-based, retrospective study (CARINA; NCT04957160), data were obtained from hospital and electronic prescribing records. Patients were aged ≥ 18 years at aRCC diagnosis and had received 1L CPI–CPI or tyrosine kinase inhibitor (TKI)–CPI combination therapy before second-line (2L) therapy including cabozantinib. We describe treatment outcomes including 1L and 2L durations of treatment (DoT) and overall survival (OS). ResultsData from April 2015 to June 2022 were collected on 281 patients from nine UK centres. Median 1L DoT was 2.3 months for CPI–CPI therapy (n = 171) and 5.0 months for TKI–CPI therapy (n = 58). After 1L CPI–CPI or TKI–CPI therapy, median 2L DoT was 5.8 versus 4.2 months, respectively, for cabozantinib (n = 163), and 3.8 versus 2.4 months for other therapies (n = 118); median 2L OS was 15.2 and 15.3 months, respectively, for cabozantinib, and 14.6 and 24.2 months for other therapies. ConclusionDoT for 2L treatment was numerically better for cabozantinib than for other therapies, and after 1L CPI–CPI therapy than after 1L TKI–CPI therapy. Median OS was similar for 2L cabozantinib and other 2L therapies, and median OS for 2L cabozantinib was similar after both 1L therapy types. These results demonstrate the antitumour effect of 2L therapies, including cabozantinib, after 1L CPI-based combination treatment, regardless of whether 1L CPI–CPI or TKI–CPI therapy is used. Micro-abstractThe retrospective CARINA study investigated treatment sequencing and outcomes for patients with advanced renal cell carcinoma who received first-line immune checkpoint inhibitor (CPI)-based combination therapy. Real-world data from medical records of 281 patients at nine UK centres (April 2015–June 2022) were analysed. Second-line therapies including cabozantinib were effective after either CPI–CPI or tyrosine kinase inhibitor–CPI combination therapy.

Neoadjuvant adebrelimab plus dalpiciclib in HPV-negative locally advanced head and neck squamous cell carcinoma: A phase II clinical trial.

TPS6129 Background: The efficacy and safety of neoadjuvant immunotherapy (NAI) for treating resectable locally advanced head and neck squamous cell carcinoma (LAHNSCC) remain uncertain, and the comprehensive protocol of NAI needs further explored. The tumor suppressor gene CDKN2A plays a pivotal role in cell cycle regulation by modulating cyclin-dependent kinase (CDK) activity. Mutations in CDKN2A lead to continuous activation of CDK4/6, resulting in uncontrolled cell proliferation and tumor growth. Approximately 35.7% of HNSCC patients exhibit CDKN2A mutations, with the incidence rising to 58% among HPV-negative LAHNSCC patients. Studies have shown that combining immunotherapy with a CDK4/6 inhibitor produces a synergistic anti-tumor effect. This study aims to assess the efficacy and safety of combining anti-PD-L1 (adebrelimab) with a CDK4/6 inhibitor (dalpiciclib) as NAI in resectable LAHNSCC patients. Methods: This open-label, single-arm, prospective phase II trial will enroll LAHNSCC patients eligible for surgery. Inclusion criteria include: being 18 to 75 years old at study entry; pathologically confirmed HPV-negative HNSCC (oral, laryngeal, hypopharyngeal, and HPV-negative oropharyngeal carcinoma), determined via p16 immunohistochemistry or HPV DNA tests; with CDKN2A mutation; resectable LAHNSCC, staged III-IVB according to the UICC/AJCC 8th edition TNM system; an ECOG Performance Status score of 0 or 1; no prior relevant anti-tumor treatments; intent for curative treatment; and adequate organ function. Key exclusion criteria are active autoimmune diseases, use of immunosuppressive drugs, or systemic corticosteroids. Eligible patients receive 3 cycles of adebrelimab (1200 mg intravenously every 3 weeks, Day 1, 22 and 43) and 2 cycles of dalpiciclib (150 mg, po, every 4 weeks, day 1-21 and 29-49) before surgery. Dose adjustments are allowed based on toxicity. Surgery will follow 2-4 weeks post-NAI, with subsequent adjuvant radiotherapy or chemoradiotherapy based on risk factors after surgery. The primary endpoints are 1-year disease-free survival (defined as the time from surgical resection to local recurrence) and major pathological response (MPR, defined as ≤10% residual viable tumor cells), with secondary endpoints focusing on safety and predictive biomarkers. Clinical trial information: NCT06199271 .

Targeted delivery of SN38 to breast cancer using amphiphilic diblock copolymers PHPMA-b-PBAEM as micellar carriers with AS1411 aptamer

Breast cancer treatment can be challenging, but a targeted drug delivery system (DDS) has the potential to make it more effective and reduce side effects. This study presents a novel nanotherapeutic targeted DDS developed through the self-assembly of an amphiphilic di-block copolymer to deliver the chemotherapy drug SN38 specifically to breast cancer cells. The vehicle was constructed from the PHPMA-b-PEAMA diblock copolymer synthesized via RAFT polymerization. A single emulsion method was then used to encapsulate SN38 within nanoparticles (NPs) formed from the PHPMA-b-PEAMA copolymer. The AS1411 DNA aptamer was covalently bonded to the surface of the micellar NPs, producing a targeted DDS. Molecular dynamics (MD) simulation studies were also performed on the di block polymeric system, demonstrating that SN38 interacted well with the di block. The in vitro results demonstrated that AS1411- decorated SN38-loaded HPMA NPs were highly toxic to breast cancer cells while having a minimal effect on non-cancerous cells. Remarkably, in vivo studies elucidated the ability of the targeted DDS to enhance the antitumor effect of SN38, suppressing tumor growth and improving survival rates compared to free SN38.

Phase I trial of chidamide, an oral HDAC inhibitor, in combination with oral etoposide in patients with refractory/recurrent neuroblastoma.

10034 Background: Chidamide, an oral subtype-selective histone deacetylase (HDAC) inhibitor, has been shown to be effective in adult patients with hematological tumors. However, there is no data on its safety and efficacy in pediatric cancer patients. Combination of HDAC inhibitors and etoposide have shown synergistic anti-tumor effects in preclinical studies of neuroblastoma. We conducted a phase I trial in pediatric patients with recurrent or refractory neuroblastoma to determine the maximum tolerable dose (MTD) of chidamide combined with oral etoposide treatment. Methods: Daily oral etoposide 35 mg/m2/dose was administered on days 1–21 in combination with escalating doses of chidamide (14 and 17 mg/m2/d) twice weekly in each 28-day cycle using the standard 3 + 3 design. Patients with response or stable disease after two cycles would maintain treatment until disease progression or unacceptable toxicity occurred. Chidamide pharmacokinetic testing was performed. Results: 31 patients were enrolled in this study. The median age was 7 years (range 3 – 18). 14 patients were included in the dose escalation phase (Ia), 17 patients in the expansion cohort (Ib). The MTD of chidamide was 14 mg/m2/d, with dose limiting neutropenia and thrombocytopenia observed at 17 mg/m2/d. Median number of cycles completed was 2.5 (range 1–11). A total of 19 patients (61.3%) experienced treatment-related grade 3/4 hematologic toxicity, and no grade 3/4 non-hematological toxicity was observed. No objective responses were seen. Conclusions: In children with refractory/recurrent neuroblastoma, chidamide is well-tolerated at 14 mg/m2/d twice weekly when combining with oral etoposide 35 mg/m2/d daily. Prolonged disease stability achieved in patients with minimal residual diseases deserves further investigation. Clinical trial information: NCT05338541 .