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Purpose This first-in-human report examined the recommended Phase 2 dose and schedule of litronesib, a selective allosteric kinesin Eg5 inhibitor. Methods Two concurrent dose-escalation studies investigated litronesib across the dose range of 0.125–16 mg/m 2 /day, evaluating the following schedules of administration on a 21-day cycle: Days 1, 2, 3; Days 1, 5, 9; Days 1, 8; Days 1, 5; or Days 1, 4, with or without pegfilgrastim. Best overall response was defined per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.0). Pharmacokinetic (PK) evaluations were performed. Exploratory PK/pharmacodynamic analyses investigated the relationship between litronesib plasma exposure and changes in phosphohistone H3 (pHH3) levels. Results One hundred and seventeen patients with advanced malignancies were enrolled. Neutropenia was the primary dose-limiting toxicity. Prophylactic pegfilgrastim reduced neutropenia frequency and severity, allowing administration of higher litronesib doses, but increases in the incidences of mucositis and stomatitis were observed. Among 86 response-evaluable patients, 2 patients (2%) achieved partial response, both on the Days 1, 2, 3 regimen (5 and 6 mg/m 2 /day with pegfilgrastim), and 17 patients (20%) maintained stable disease for ≥6 cycles. Dose-dependent increases in litronesib plasma exposure were observed, with minor intra- and inter-cycle accumulation, along with exposure-dependent increases in pHH3 expression in tumor and skin biopsies. Conclusions On the basis of the results of these studies, two regimens were selected for Phase 2 exploration: 6 mg/m 2 /day on Days 1, 2, 3 plus pegfilgrastim and 8 mg/m 2 /day on Days 1, 5, 9 plus pegfilgrastim, both on a 21-day cycle.

Leucine-rich repeat kinase 2 ( LRRK2 ) is the most commonly mutated gene in familial Parkinson’s disease 1 and is also linked to its idiopathic form 2 . LRRK2 has been proposed to function in membrane trafficking 3 and colocalizes with microtubules 4 . Despite the fundamental importance of LRRK2 for understanding and treating Parkinson’s disease, structural information on the enzyme is limited. Here we report the structure of the catalytic half of LRRK2, and an atomic model of microtubule-associated LRRK2 built using a reported cryo-electron tomography in situ structure 5 . We propose that the conformation of the LRRK2 kinase domain regulates its interactions with microtubules, with a closed conformation favouring oligomerization on microtubules. We show that the catalytic half of LRRK2 is sufficient for filament formation and blocks the motility of the microtubule-based motors kinesin 1 and cytoplasmic dynein 1 in vitro. Kinase inhibitors that stabilize an open conformation relieve this interference and reduce the formation of LRRK2 filaments in cells, whereas inhibitors that stabilize a closed conformation do not. Our findings suggest that LRRK2 can act as a roadblock for microtubule-based motors and have implications for the design of therapeutic LRRK2 kinase inhibitors. The structure of the catalytic half of LRRK2 and an atomic model of microtubule-associated LRRK2 suggest that the conformation of the kinase controls the association of LRRK2 with microtubules.

Summary Background AZD4877 is a potent inhibitor of the mitotic spindle kinesin, Eg5. Early-phase clinical studies in a broad range of cancers showed that AZD4877 is well tolerated. This Phase II study evaluated the efficacy, safety and pharmacokinetics (C max ) of AZD4877 in patients with previously treated advanced urothelial cancer (ClinicalTrials.gov identifier NCT00661609). Patients and methods AZD4877 25 mg was administered once-weekly for 3 weeks of each 4-week cycle until disease progression, death, unacceptable toxicity or withdrawal. The primary objective was to determine the objective response rate (RECIST). Recruitment was to be halted if ≤2 of the first 20 evaluable patients achieved an objective tumor response. C max was assessed on days 1 and 8 of cycle 1. Results None of the first 20 patients evaluable for efficacy achieved an objective response; enrollment was therefore halted. During this initial analysis, a further 21 patients were recruited. Overall, 39 patients were evaluable for efficacy, including one with confirmed partial response (PR) and seven patients with stable disease for ≥8 weeks (including one unconfirmed PR). The most commonly reported treatment-related adverse events (TRAEs) were neutropenia (22 patients), fatigue (12), leukopenia (7) and constipation (6); the most commonly reported grade ≥3 TRAE was neutropenia (21). Four patients had serious TRAEs. On days 1 and 8, the geometric mean C max of AZD4877 was 138 ng/ml (CV = 75 %) and 144 ng/ml (CV = 109 %), respectively. Conclusions AZD4877 was generally tolerable in patients with advanced urothelial cancer. Given the limited clinical efficacy, further development of AZD4877 in urothelial cancer is not planned.

Summary Eg5 (kinesin spindle protein) is a microtubule motor protein, essential for centrosome separation during mitosis. This Phase I/II, open-label, multicenter, two-part study investigated AZD4877, a potent Eg5 inhibitor, in patients with acute myeloid leukemia. Primary objectives were to determine the maximum tolerated dose (MTD) (part A), assess efficacy (part B) and determine the pharmacokinetic profile (parts A and B). Secondary objectives included assessment of safety and tolerability. AZD4877 was administered at a range of doses (2, 4, 7, 10, 13, 16 and 18 mg/day) as a 1-hour intravenous infusion on three consecutive days of a continuous 2-week schedule. The MTD in part A was defined as 16 mg/day based on dose-limiting stomatitis at 16 and 18 mg/day, hyperbilirubinemia at 16 mg/day and palmar–plantar erythrodysesthesia syndrome at 18 mg/day. Systemic exposure to AZD4877 generally increased with increasing dose whereas half-life was not dose dependent. No evaluable patients experienced a complete remission (CR) or CR with incomplete blood count recovery (CRi), demonstrating no evidence of AZD4877 efficacy in this population. Evidence of monoasters in all but the 4 mg/day dose group provided proof of mechanism for AZD4877. This study was terminated due to lack of efficacy. (ClinicalTrials.gov identifier NCT00486265).

Using high-coverage targeted next-generation sequencing, this report provides a catalog of genetic alterations in colorectal and lung cancers, identifying previously unknown alterations, such as JAK2 mutations and KIF5B-RET fusions, that may represent druggable targets. Applying a next-generation sequencing assay targeting 145 cancer-relevant genes in 40 colorectal cancer and 24 non–small cell lung cancer formalin-fixed paraffin-embedded tissue specimens identified at least one clinically relevant genomic alteration in 59% of the samples and revealed two gene fusions, C2orf44-ALK in a colorectal cancer sample and KIF5B-RET in a lung adenocarcinoma. Further screening of 561 lung adenocarcinomas identified 11 additional tumors with KIF5B-RET gene fusions (2.0%; 95% CI 0.8–3.1%). Cells expressing oncogenic KIF5B-RET are sensitive to multi-kinase inhibitors that inhibit RET.

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and is the fourth-leading cause of cancer-related deaths worldwide. HCC is refractory to many standard cancer treatments and the prognosis is often poor, highlighting a pressing need to identify biomarkers of aggressiveness and potential targets for future treatments. Kinesin family member 2C (KIF2C) is reported to be highly expressed in several human tumors. Nevertheless, the molecular mechanisms underlying the role of KIF2C in tumor development and progression have not been investigated. In this study, we found that KIF2C expression was significantly upregulated in HCC, and that KIF2C up-regulation was associated with a poor prognosis. Utilizing both gain and loss of function assays, we showed that KIF2C promoted HCC cell proliferation, migration, invasion, and metastasis both in vitro and in vivo. Mechanistically, we identified TBC1D7 as a binding partner of KIF2C, and this interaction disrupts the formation of the TSC complex, resulting in the enhancement of mammalian target of rapamycin complex1 (mTORC1) signal transduction. Additionally, we found that KIF2C is a direct target of the Wnt/β-catenin pathway, and acts as a key factor in mediating the crosstalk between Wnt/β-catenin and mTORC1 signaling. Thus, the results of our study establish a link between Wnt/β-catenin and mTORC1 signaling, which highlights the potential of KIF2C as a therapeutic target for the treatment of HCC.

Kinesin-like protein 18A (KIF18A) is a member of the kinesin family of molecular motor proteins, which utilise energy from the hydrolysis of adenosine triphosphate (ATP) to regulate critical cellular processes such as chromosome movement and microtubule dynamics. KIF18A plays a vital role in controlling microtubule length, which is crucial for maintaining proper cell function and division. Notably, increased expression levels of KIF18A have been observed in various types of cancer, indicating its potential involvement in tumour progression. Although preclinical studies have demonstrated that KIF18A is not essential for normal somatic cell division, it appears to be crucial for the survival and division of cancer cells, particularly those exhibiting chromosomal instability. This dependency makes KIF18A a promising target for developing new therapeutic strategies aimed at treating chromosomally unstable cancers. This review delves into the structural and functional aspects of KIF18A, and its role in cancer development, and evaluates current and emerging approaches to targeting KIF18A with innovative cancer treatments.

Triple-negative breast cancer (TNBC), being both aggressive and highly lethal, poses a major clinical challenge in terms of treatment. Its heterogeneity and lack of hormone receptors or HER2 expression further restrict the availability of targeted therapy. Breast cancer stem cells (BCSCs), known to fuel TNBC malignancy, are now being exploited as a vulnerability for TNBC treatment. Here, we dissected the transcriptome of BCSCs and identified kinesin family member 20A (KIF20A) as a key regulator of BCSC survival and TNBC tumorigenesis. Genetic depletion or pharmacological inhibition of KIF20A impairs BCSC viability and tumor initiation and development in vitro and in vivo. Mechanistically, KIF20A supports BCSC stemness through modulation of mitochondrial oxidative phosphorylation, which is repressed by SMARCA4, a component of the SWI/SNF chromatin remodeling complex. Therapeutically, KIF20A inhibition sensitizes TNBC xenografts to standard-of-care chemotherapy. Our study highlights the importance of targeting KIF20A to exploit BCSC vulnerabilities in TNBC.

Chromosome instability is a prevalent vulnerability of cancer cells that has yet to be fully exploited therapeutically. To identify genes uniquely essential to chromosomally unstable cells, we mined the Cancer Dependency Map for genes essential in tumor cells with high levels of copy number aberrations. We identify and validate KIF18A, a mitotic kinesin, as a vulnerability of chromosomally unstable cancer cells. Knockdown of KIF18A leads to mitotic defects and reduction of tumor growth. Screening of a chemical library for inhibitors of KIF18A enzymatic activity identified a hit that was optimized to yield VLS-1272, which is orally bioavailable, potent, ATP non-competitive, microtubule-dependent, and highly selective for KIF18A versus other kinesins. Inhibition of KIF18A’s ATPase activity prevents KIF18A translocation across the mitotic spindle, resulting in chromosome congression defects, mitotic cell accumulation, and cell death. Profiling VLS-1272 across >100 cancer cell lines demonstrates that the specificity towards cancer cells with chromosome instability differentiates KIF18A inhibition from other clinically tested anti-mitotic drugs. Treatment of tumor xenografts with VLS-1272 results in mitotic defects leading to substantial, dose-dependent inhibition of tumor growth. The strong biological rationale, robust preclinical data, and optimized compound properties enable the clinical development of a KIF18A inhibitor in cancers with high chromosomal instability. Chromosomal instability occurs frequently in cancer, making it an attractive therapeutic target. Here, the authors identify KIF18A as a targetable vulnerability of cancer cells with chromosomal instability and target this using VLS-1272, a selective KIF18A inhibitor.

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide. The poor survival may be due to a high proportions of tumor recurrence and metastasis. Kinesin family member C1 (KIFC1) is highly expressed in a variety of neoplasms and is a potential marker for non-small cell lung cancer or ovarian adenocarcinoma metastasis. Nevertheless, the role of KIFC1 in HCC metastasis remains obscure. We investigated this in the present study using HCC cell lines and clinical specimens. Our results indicated that increased levels of KIFC1 were associated with poor prognosis and metastasis in HCC. In addition, KIFC1 induced epithelial-to-mesenchymal transition (EMT) and HCC metastasis both in vitro and in vivo. This tumorigenic effect depended on gankyrin; inhibiting gankyrin activity reversed EMT via activation of protein kinase B (AKT)/Twist family BHLH transcription factor 1 (AKT/TWIST1). We also found that KIFC1 was directly regulated by the microRNA miR-532-3p, whose downregulation was associated with metastatic progression in HCC. These results denote that a decrease in miR-532-3p levels results in increased KIFC1 expression in HCC, leading to metastasis via activation of the gankyrin/AKT/TWIST1 signaling pathway.