PURPOSE: Datopotamab deruxtecan (Dato-DXd) is an antibody-drug conjugate consisting of a humanized antitrophoblast cell-surface antigen 2 (TROP2) monoclonal antibody linked to a potent, exatecan-derived topoisomerase I inhibitor payload via a plasma-stable, selectively cleavable linker. PATIENTS AND METHODS: TROPION-PanTumor01 (ClinicalTrials.gov identifier: NCT03401385 ) is a phase I, dose-escalation, and dose-expansion study evaluating Dato-DXd in patients with previously treated solid tumors. The primary study objective was to assess the safety and tolerability of Dato-DXd. Secondary objectives included evaluation of antitumor activity and pharmacokinetics. Results from patients with advanced/metastatic hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2–) breast cancer (BC) or triple-negative BC (TNBC) are reported. RESULTS: At data cutoff (July 22, 2022), 85 patients (HR+/HER2– BC = 41, and TNBC = 44) had received Dato-DXd. The objective response rate by blinded independent central review was 26.8% (95% CI, 14.2 to 42.9) and 31.8% (95% CI, 18.6 to 47.6) for patients with HR+/HER2– BC and TNBC, respectively. The median duration of response was not evaluable in the HR+/HER2– BC cohort and 16.8 months in the TNBC cohort. The median progression-free survival in patients with HR+/HER2– BC and TNBC was 8.3 and 4.4 months, respectively. All-cause treatment-emergent adverse events (TEAEs; any grade, grade ≥3) were observed in 100% and 41.5% of patients with HR+/HER2– BC and 100% and 52.3% of patients with TNBC. Stomatitis was the most common TEAE (any grade, grade ≥3) in both HR+/HER2– BC (82.9%, 9.8%) and TNBC (72.7%, 11.4%) cohorts. CONCLUSION: In patients with heavily pretreated advanced HR+/HER2– BC and TNBC, Dato-DXd demonstrated promising clinical activity and a manageable safety profile. Dato-DXd is currently being evaluated in phase III studies.

Purpose: A growing number of treatment options and active compounds in treatments have led to better outcomes for patients with advanced or recurrent epithelial ovarian cancer. We examined the association between progression-free survival (PFS), post-progression survival (PPS) and overall survival (OS) in phase III trials of second- and third-line chemotherapy for advanced or recurrent epithelial ovarian cancer. We aim to determine whether PFS or PPS is a surrogate of OS so that we can decide progress of disease is optimal endpoint for ovarian cancer.

Human epidermal growth factor receptor 3 (HER3) is a receptor tyrosine kinase that is expressed in numerous solid tumors. Higher levels of HER3 expression in multiple tumor types are associated with adverse clinical outcomes, such as reduced survival. However, there is currently no HER3-directed antibody-drug conjugate approved for the treatment of any cancer. Improved treatment options are needed, in particular for patients who progress on standard therapies. HER3-DXd is an investigational HER3-directed antibody-drug conjugate composed of an anti-HER3 monoclonal antibody linked to a topoisomerase I inhibitor payload via a stable tetrapeptide-based cleavable linker. In previous clinical trials, HER3-DXd demonstrated a manageable safety profile and durable efficacy in previously treated, advanced EGFR-mutated NSCLC and advanced breast cancer across a range of baseline tumor HER3 expression levels. HER3-DXd has also shown preclinical antitumor efficacy in HER3-expressing cancers including cutaneous melanoma, gastric cancer, and prostate cancer, among others. The aim of this global phase II HERTHENA-PanTumor01 multicohort study is to assess the efficacy and safety of HER3-DXd in patients with relapsed or refractory locally advanced or metastatic solid tumors including melanoma, head and neck squamous cell, gastric/gastroesophageal junction, ovarian, cervical, endometrial, bladder, esophageal squamous cell, pancreatic, and prostate cancers.Clinical trial registration: NCT06172478 (ClinicalTrials.gov); 2023-507641-29-00 (EudraCT); jRCT2031230575 (Japan Registry of Clinical Trials).

Triple-negative breast cancer (TNBC) has high relapse and metastasis rates and a high proportion of cancer stem-like cells (CSC), which possess self-renewal and tumor initiation capacity. MELK (maternal embryonic leucine zipper kinase), a protein kinase of the Snf1/AMPK kinase family, is known to promote CSC maintenance and malignant transformation. However, the role of MELK in TNBC metastasis is unknown; we sought to address this in the current study. We found that MELK mRNA levels were higher in TNBC tumors [8.11 (3.79–10.95)] than in HR+HER2− tumors [6.54 (2.90–9.26)]; P < 0.001]. In univariate analysis, patients with breast cancer with high-MELK–expressing tumors had worse overall survival (P < 0.001) and distant metastasis-free survival (P < 0.01) than patients with low-MELK–expressing tumors. In a multicovariate Cox regression model, high MELK expression was associated with shorter overall survival after adjusting for other baseline risk factors. MELK knockdown using siRNA or MELK inhibition using the MELK inhibitor MELK-In-17 significantly reduced invasiveness, reversed epithelial-to-mesenchymal transition, and reduced CSC self-renewal and maintenance in TNBC cells. Nude mice injected with CRISPR MELK-knockout MDA-MB-231 cells exhibited suppression of lung metastasis and improved overall survival compared with mice injected with control cells (P < 0.05). Furthermore, MELK-In-17 suppressed 4T1 tumor growth in syngeneic BALB/c mice (P < 0.001). Our findings indicate that MELK supports metastasis by promoting epithelial-to-mesenchymal transition and the CSC phenotype in TNBC.Significance: These findings indicate that MELK is a driver of aggressiveness and metastasis in TNBC.

A liposomal formulation of eribulin, E7389-LF, may provide improved pharmacokinetics and allow increased access to tumour tissues. This expansion of a phase 1 study assessed the safety and efficacy of E7389-LF in patients with human epidermal growth factor receptor type 2-negative metastatic breast cancer. Patients received E7389-LF 2.0 mg/m² every three weeks. Tumour assessments were conducted every six weeks by the investigator by Response Evaluation Criteria in Solid Tumours v1.1. All adverse events were monitored and recorded. Serum biomarker assessments were conducted. Of 28 patients included, 75.0% had hormone receptor-positive breast cancer (HR+ BC) and 25.0% had triple-negative breast cancer (TNBC). The most common grade ≥3 treatment-related treatment-emergent adverse events included neutropenia (67.9%), leukopenia (42.9%), thrombocytopenia (32.1%), and febrile neutropenia (25.0%). Rates of neutropenia and febrile neutropenia were lower among patients who received prophylactic pegfilgrastim. Objective response rate was 35.7% (95% confidence interval [CI]: 18.6-55.9) for all patients and 42.9% (95% CI: 21.8-66.0) for patients with HR+ BC. Median progression-free survival was 5.7 months (95% CI: 3.9-8.3). The median overall survival was 18.3 months (95% CI: 13.2-not estimable). Among the 54 biomarkers assessed, 27, including 5 of 7 vascular markers, were significantly altered by E7389-LF treatment from baseline to any time point. E7389-LF was tolerable and favourable antitumour activity was observed, particularly in patients with HR+ BC. Prophylactic pegfilgrastim can be considered in patients at high risk for neutropenia and febrile neutropenia. NCT03207672.

Summary: Background: Talazoparib is a poly(ADP-ribose) polymerase enzyme inhibitor. This open-label, non-randomized, phase 1 study of talazoparib investigated the safety, pharmacokinetics, and preliminary antitumor activity in Japanese patients with locally advanced or metastatic solid tumors, regardless of mutations in DNA damage repair-related genes, who are resistant to/ineligible for standard therapies. Methods: Patients received talazoparib dosed orally at 0.75 or 1 mg once daily using a modified 3 + 3 dose-escalation scheme. Primary endpoint was dose-limiting toxicities during the first cycle of talazoparib. Results: Nine patients (median age 62.0 years) were included: 3 and 6 patients at the 0.75 and 1.0 mg once-daily dose levels, respectively. No dose-limiting toxicities were reported. The most commonly reported treatment-emergent adverse events (≥2 patients) were anemia, stomatitis, maculopapular rash, platelet count decreased, neutrophil count decreased, and alanine aminotransferase increased. Three patients had grade ≥ 3 treatment-emergent adverse events (anemia, brain metastases [1 patient each], and neutrophil and white blood cell count decreased [same patient]). Two patients temporarily discontinued treatment due to a treatment-emergent adverse event, and 1 patient required a dose reduction for neutrophil count decreased (all at 1 mg once daily). Talazoparib exposure (C_max and AUC) after single and multiple dosing was slightly higher proportionally with talazoparib 1 mg than talazoparib 0.75 mg. The overall disease control rate was 44.4%, including 2 patients with stable disease. The recommended phase 2 dose of talazoparib was established as 1 mg once daily. Conclusions: Single-agent talazoparib was well tolerated and had preliminary antitumor activity in Japanese patients with advanced solid tumors. ClinicalTrials.gov identifier: NCT03343054 (November 17, 2017).