Antibody-drug conjugates (ADCs) using DNA Topoisomerase I inhibitor DXd/SN-38 have transformed cancer treatment, yet more effective ADCs are needed for overcoming resistance. We have designed an ADC class using a novel self-immolative T moiety for traceless conjugation and release of exatecan, a more potent Topoisomerase I inhibitor with less sensitivity to multidrug (MDR) resistance. Characterized by enhanced therapeutic indices, higher stability and improved intra-tumoral pharmacodynamic response, antibody-T moiety-exatecan conjugates targeting HER2, HER3, TROP2 overcome intrinsic or treatment-resistance of equivalent DXd/SN-38 ADCs in low-target expression, large-size and MDR+ tumors. T moiety-exatecan ADCs display durable antitumor activity in PDX and organoid models representative of unmet clinical needs including EGFR-del19/T790M/C797S triple mutation lung cancer and BRAF/KRAS–TP53 double-mutant colon cancer, and show synergy with PARP/ATR inhibitor and anti-PD-1 treatment. High tolerability of T moiety-exatecan ADC class in non-human primate supports its potential to expand responding patient population and tumor types beyond current ADCs.

Paclitaxel (PTX), a tubulin-binding agent, is widely used and has shown good efficacy in the initial period of treatment for non-small cell lung cancer (NSCLC). However, the relatively rapid acquisition of resistance to PTX treatments that is observed in virtually all cases significantly limits its utility and remains a substantial challenge to the clinical management of NSCLC. The aim of this study was to identify candidate genes and mechanisms that might mediate acquired paclitaxel resistance. In this work, we established paclitaxel-resistant cells (A549-T) from parental cell lines by step-dose selection in vitro. Using methylation chip analysis and transcriptome sequencing, 43,426 differentially methylated genes and 2,870 differentially expressed genes are identified. Six genes (KANK1, ALDH3A1, GALNT14, PIK3R3, LRG1, WEE2), which may be related to paclitaxel resistance in lung adenocarcinoma, were identified. Among these genes, KANK1 exhibited significant differences in methylation and expression between cell lines. Since KANK1 plays an important role in the development of renal cancer and gastric cancer, we hypothesised that it may also play a role in acquired resistance in lung adenocarcinoma. Transient transfection of SiKANK1 significantly reduced the expression of KANK1, reducing apoptosis, increasing cell migration, and enhancing the tolerance of A549 cells to paclitaxel. KANK1 acts as a tumour suppressor gene, mediating the resistance of lung adenocarcinoma A549 to paclitaxel. The reduction of KANK1 expression can increase the paclitaxel resistance of non-small cell lung cancer and increase the difficulty of clinical treatment.

was applied to analyze the association of ER signal pathway with the 10 DEGs. 3 significant genes (GFRA3, NPY1R and PTPRN2) were closely related to ER related pathway. These significant DEGs regulated many biological activities such as cell proliferation and survival, motility and migration, and tumor cell invasion. The interactions between these DEGs and drug resistance phenomenon need to be further elucidated at a functional level in further studies. Based on our findings, we believed that these DEGs could be therapeutic targets, which can be explored to develop new treatment options.

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths worldwide. 5-fluorouracil (5-FU)-based chemotherapeutic regimens are routinely used for the treatment of patients with CRC. However, recurrence and chemotherapeutic drug resistance limit the survival rates of patients with CRC. DNA methylation participates in diverse cellular processes by regulating the transcription of a large number of genes expression, cell division, apoptosis, cell adhesion and differentiation, and metabolism, thus it might mediate chemoresistance. Using an Illumina Infinium HD Assay, DNA methylation levels in a human 5-FU-resistant HCT-8 CRC cell line (HCT-8/FU) and its progenitor cell line HCT-8 were analysed. A total of 16,580 differentially methylated genes were identified, of which 8885 were hypermethylated and 7695 were hypomethylated in resistant cells. Among these genes, NME2 (nucleoside diphosphate kinase 2) exhibited a significant difference in methylation between cell lines and has known roles in gastric cancer and breast cancer; accordingly, we hypothesized that it plays a role in acquired resistance in CRC. Knockdown of NME2 restored 5-FU sensitivity in 5-FU-resistant CRC cells, reduced cell survival and increased cell apoptosis; and overexpression of NME2 in HCT-8 cells results in the acquisition of resistance to 5-FU, this alteration enhanced HCT-8 cells growth abilities and reduced apoptosis. These findings suggest that NME2 mediates chemoresistance to 5-FU in CRC and that specific NME2 inhibition could optimize 5-FU-based chemotherapy of CRC.

HER3 is a unique member of the epidermal growth factor receptor family of tyrosine kinases, which is broadly expressed in several cancers, including breast, lung, pancreatic, colorectal, gastric, prostate, and bladder cancers and is often associated with poor patient outcomes and therapeutic resistance. U3-1402/Patritumab-GGFG-DXd is the first successful HER3-targeting ADC molecule with clinical efficacy in non-small cell lung cancer (NSCLC). However, over 60% of patients are non-responsive to U3-1402 due to low target expression levels and responses tend to be in patients with higher target expression levels. U3-1402 is also ineffective in more challenging tumor types such as colorectal cancer. AMT-562 was generated by a novel anti-HER3 antibody Ab562 and a modified self-immolative PABC spacer (T800) to conjugate exatecan. Exatecan showed higher cytotoxic potency than its derivative DXd. Ab562 was selected due to its moderate affinity for minimizing potential toxicity and improving tumor penetration purposes. Both alone or in combination therapies, AMT-562 showed potent and durable antitumor response in low HER3 expression xenograft and heterogeneous patient-derived xenograft/organoid (PDX/PDO) models, including digestive system and lung tumors representing of unmet needs. Combination therapies pairing AMT-562 with therapeutic antibodies, inhibitors of CHEK1, KRAS and TKI showed higher synergistic efficacy than Patritumab-GGFG-DXd. Pharmacokinetics and safety profiles of AMT-562 were favorable and the highest dose lacking severe toxicity was 30 mg/kg in cynomolgus monkeys. AMT-562 has potential to be a superior HER3-targeting ADC with a higher therapeutic window that can overcome resistance to generate higher percentage and more durable responses in U3-1402-insensitive tumors.

Objective: Lung cancer is a malignant tumor with the highest mortality rate in the world. It is necessary to develop effective biomarkers for diagnosis or prognostic treatment to improve the survival rate of patients. In this prospective study, we identified a membrane-expressed protein Tight Junction Protein 1 (TJP1), which is an ideal therapeutic target for lung cancer, and demonstrated its role in invasion, migration, and proliferation of lung cancer. Methods: High-throughput monoclonal antibody microarrays were used to screen for differential expression of monoclonal antibodies (mAbs) in lung cancer and normal lung tissue. Differentially expressed antibodies were used to immunoprecipitate their cellular targets to be identified by mass spectrometry. The identified target TJP1 was knocked down to observe the effect of reduced gene expression on lung cancer cell function. Immunohistochemistry on human tumor tissues and The Cancer Genome Atlas (TCGA) database was used to explore the relationship between TJP1 expression in multiple cancer types and patient prognosis. Results: The antibody CL007473 was overexpressed in tumor tissue and its target protein was identified by mass spectrometry and immunofluorescence as TJP1, a membrane-expressed protein. Knockdown of TJP1 in lung cancer cell lines showed that reduced expression of TJP1 could inhibit the invasion and migration of lung cancer cells and inhibit the proliferation of cancer cells, suggesting that membrane-expressed protein TJP1 may be used as a therapeutic target for lung cancer. TCGA database analysis showed that TJP1 was highly expressed in pancreatic cancer (PAAD) tissues compared with normal tissues, and low expression was more beneficial to the prognosis and survival of PAAD patients. Conclusion: Membrane-expressed protein TJP1 may be a good therapeutic and prognostic target for lung cancer and has the potential to be a prognostic biomarker in pancreatic cancer.

<p>Supplementary note shows the analytical characterization of the ADCs, and synthesis of drug-linkers</p>

<p>Supplementary Figure S1 shows Exatecan cytotoxicity and sensitivity to multidrug resistant genes. Supplementary Figure S2 shows Exatecan and DXd/SN-38 sensitivity to multidrug resistant genes. Supplementary Figure S3 shows Exatecan toxicity in rat. Supplementary Figure S4 shows the design and optimization of T moiety. Supplementary Figure S5 shows physicochemical and functional equivalence of Tras-GGFG-DXd and DS-8201a. Supplementary Figure S6 show physicochemical profile of antibody-exatecan conjugates enabled by T moiety. Supplementary Figure S7 shows additional T moiety-exatecan and belotecan conjugates. Supplementary Figure S8 shows in vitro and in vivo stability of MTX-1000. Supplementary Figure S9 shows cellular dynamics and mechanism of MTX-1000. Supplementary Figure S10 shows colon cancer organoid response to ADCs. Supplementary Figure S11 shows bystander killing effect of MTX-1000, T-DM1 and Tras-GGFG-DXd in coculture conditions in vitro. Supplementary Figure S12 shows hematology and serum chemistry of MTX-1000 in monkey. Supplementary Figure S13 shows T moiety-exatecan ADCs show potent antitumor efficacy and improved therapeutic index. Supplementary Figure S14 shows T moiety-exatecan ADCs show higher antitumor potency in PDX models and better intratumor pharmacodynamic response. Supplementary Figure S15 shows T moiety-exatecan ADCs overcome treatment-resistance due to improved therapeutic index and intratumor pharmacodynamic response. Supplementary Figure S16 shows overcoming MDR resistance by T moiety exatecan ADCs or a combination of MDR inhibitor with DXd/SN-38 ADCs. Supplementary Figure S17 shows Exatecan/MTX-1000 and PARP/ATR inhibitor synergize in colon cancer cells. Supplementary Figure S18 shows a patient-derived xenograft (PDX) model with EGFR triple mutation. Supplementary Figure S19 shows MTX-1000 induces immunological cell death and enhances antitumor immunity of anti-PD-1.</p>