Tongtong Xue

A severe upper respiratory tract syndrome caused by the new coronavirus has now spread to the entire world as a highly contagious pandemic. The large scale explosion of the disease is conventionally traced back to January of this year in the Chinese province of Hubei, the wet markets of the principal city of Wuhan being assumed to have been the specific causative locus of the sudden explosion of the infection. A number of findings that are now coming to light show that this interpretation of the origin and history of the pandemic is overly simplified. A number of variants of the coronavirus would in principle have had the ability to initiate the pandemic well before January of this year. However, even if the COVID-19 had become, so to say, ready, conditions in the local environment would have had to prevail to induce the loss of the biodiversity's "dilution effect" that kept the virus under control, favoring its spillover from its bat reservoir to the human target. In the absence of these appropriate conditions only abortive attempts to initiate the pandemic could possibly occur: a number of them did indeed occur in China, and probably elsewhere as well. These conditions were unfortunately present at the wet marked in Wuhan at the end of last year.

Antibody–drug conjugates (ADCs) have emerged as a transformative modality in the treatment of solid tumors. YL201, a novel B7H3-targeting ADC, leverages a tumor microenvironment activable linker-payload platform, coupled with a novel topoisomerase 1 inhibitor via a protease-cleavable linker. Here we report the findings from a large-scale, global, multicenter, phase 1 trial evaluating the safety, pharmacokinetics and preliminary efficacy of YL201 in patients with advanced solid tumors refractory to standard therapies. The trial included a dose-escalation part (phase 1) and a dose-expansion part (phase 1b). A total of 312 patients were enrolled across multiple tumor types, including extensive-stage small cell lung cancer (ES-SCLC), nasopharyngeal carcinoma (NPC), non-small cell lung cancer, esophageal squamous cell carcinoma and other solid tumors. The maximum tolerated dose was determined to be 2.8 mg kg−1, and the recommended expansion dose was selected as 2.0 mg kg−1 and 2.4 mg kg−1 every 3 weeks. The most common grade 3 or higher treatment-related adverse events included neutropenia (31.7%), leukopenia (29.5%) and anemia (25.0%). Only 4 cases of interstitial lung disease (1.3%) and 1 case of infusion reactions (0.3%) were observed. Encouraging anti-tumor activity was observed, particularly in patients with ES-SCLC (objective response rate (ORR), 63.9%), NPC (ORR, 48.6%), lung adenocarcinoma (ORR, 28.6%) and lymphoepithelioma-like carcinoma (ORR, 54.2%). No significant correlation between B7H3 membrane expression and the ORR was found. YL201 demonstrated an acceptable safety profile and a promising efficacy in heavily pretreated patients with advanced solid tumors, particularly in those with ES-SCLC, NPC or lymphoepithelioma-like carcinoma. Phase 3 clinical trials for patients with SCLC and NPC have already been initiated. ClinicalTrials.gov identifiers: NCT05434234 and NCT06057922 . In a large-scale, international, multicenter, phase 1/1b trial, treatment of patients with advanced solid tumors with the B7H3-targeting antibody–drug conjugate YL201 was safe and showed preliminary clinical efficacy.

Myeloid-derived suppressor cells (MDSCs) play an important role in tumor immune escape. Recent studies have shown that MDSCs contribute to tumor progression under psychological stress, but the underlying mechanism of MDSCs mobilization and recruitment remains largely unknown. In the present study, a chronic restraint stress paradigm was applied to the H22 hepatocellular carcinoma (HCC) bearing mice to mimic the psychological stress. We observed that chronic restraint stress significantly promoted HCC growth, as well as the mobilization of MDSCs to spleen and tumor sites from bone marrow. Meanwhile, chronic restraint stress enhanced the expression of C-X-C motif chemokine receptor 2 (CXCR2) and pErk1/2 in bone marrow MDSCs, together with elevated chemokine (C-X-C motif) ligand 5 (CXCL5) expression in tumor tissues. In vitro, the treatments of MDSCs with epinephrine (EPI) and norepinephrine (NE) but not corticosterone (CORT)-treated H22 conditioned medium obviously inhibited T-cell proliferation, as well as enhanced CXCR2 expression and extracellular signal-regulated kinase (Erk) phosphorylation. In vivo, β-adrenergic blockade with propranolol almost completely reversed the accelerated tumor growth induced by chronic restraint stress and inactivated CXCL5-CXCR2-Erk signaling pathway. Our findings support the crucial role of β-adrenergic signaling cascade in the mobilization and recruitment of MDSCs under chronic restraint stress.

1049 Background: HER2 is an effective therapeutic target for breast and gastric cancer. A166 is an antibody-drug conjugate composed of a novel cytotoxic drug site-specifically conjugated to transtuzumab sequence via a stable protease-cleavable valine citrulline linker. Methods: This was a single arm, open-label, multicenter, dose escalating Phase 1 first-in-human study of A166 as monotherapy in solid tumor patients. Dose escalation and MTD identification was directed using a Bayesian logistic regression model with overdose control. The following dose levels were evaluated in this study: 0.3, 1.2, 3.6, 4.8 mg/kg. (ClinicalTrials.gov NCT03602079) Results: As of November 1, 2019 35 pts have completed the DLT evaluation period across 4 dose levels. Overall, A166 had an acceptable toxicity profile with no unexpected toxicities related to the study drug. No adverse events recorded met the protocol specified definition of a dose limiting toxicity at any studied dose level. Most frequently (≥10%) occurring TEAEs include were Keratitis, Decreased appetite, Dry eye, Vision blurred etc. Overall incidence of ophthalmic toxicities in the 3.6 mg/kg cohort was 80% and in the 4.8 mg/kg cohort it was 83%. Among the 27 patients evaluable for efficacy, best response was progression of disease in 11 patients (41%), stable disease in 9 patients (33%) and partial response in 7 patients (26%), for the total disease control rate of 59%.Responses were seen only at the dose levels of 3.6 mg/kg and 4.8 mg/kg. Conclusions: A166 demonstrated clinically meaningful efficacy in heavily pretreated patients with relapsed or refractory advanced solid cancers. The achievement of an ORR of 36% at efficacious dose levels and up to 100% in HER2 positive patients regardless of histology (2 CRC, 1 BC and 1 NSCLC) at the highest studied dose level exceed Clinical trial information: NCT03602079 .