Phase II study of ispinesib in recurrent or metastatic squamous cell carcinoma of the head and neck

Phase I/II multicenter study to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of AZD4877 in patients with refractory acute myeloid leukemia

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).

Overexpression of Eg5 predicts unfavorable prognosis in non-muscle invasive bladder urothelial carcinoma

OBJECTIVE

To investigate the relationship between Eg5 expression and prognosis of patients with non-muscle invasive bladder urothelial carcinoma.

METHODS

Eg5 expression was examined by immunohistochemistry in non-muscle invasive urothelial carcinoma specimens (grade: G1, 32 cases; G2, 92 cases; and G3, 39 cases. Stage: pTa, 49 cases and pT1, 114 cases). The correlation between clinicopathological characteristics and Eg5 expression was evaluated. The prognostic significance of Eg5 immunoreactivity was analyzed through survival analysis in 163 non-muscle invasive cases that were treated with transurethral resection and adjuvant intravesical instillations.

RESULTS

The expression of Eg5 was significantly associated with tumor grade (P = 0.006), with a trend towards significant association with stage (P = 0.057). The 163 patients with non-muscle invasive tumors were regularly followed with the mean of 32.52 (from 6 to 72) months. Univariate analysis showed Eg5 overexpression exhibited a significant unfavorable influence on intravesical recurrence (P = 0.012) while having only a marginal correlation with disease progression (P = 0.070). Subsequent Cox hazard multivariate analysis showed that both grade (P = 0.045) and Eg5 expression (P = 0.029) were independent predictors for early intravesical recurrence.

CONCLUSIONS

Overexpression of Eg5 correlates with poor differentiation of bladder cancer, and it represents an independent prognostic factor in predicting early intravesical recurrence in non-muscle invasive bladder carcinoma patients.

The association between EGFR variant III, HPV, p16, c-MET, EGFR gene copy number and response to EGFR inhibitors in patients with recurrent or metastatic squamous cell carcinoma of the head and neck

Background

We examine the potential prognostic and predictive roles of EGFR variant III mutation, EGFR gene copy number (GCN), human papillomavirus (HPV) infection, c-MET and p16^INK4A protein expression in recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN).

Methods

We analyzed the archival tumor specimens of 53 patients who were treated in 4 phase II trials for R/M SCCHN. Two trials involved the EGFR inhibitor erlotinib, and 2 trials involved non-EGFR targeted agents. EGFRvIII mutation was determined by quantitative RT-PCR, HPV DNA by Linear Array Genotyping, p16 and c-MET protein expression by immunohistochemistry, and EGFR GCN by FISH.

Results

EGFRvIII mutation, detected in 22 patients (42%), was associated with better disease control, but no difference was seen between erlotinib-treated versus non-erlotinib treated patients. EGFRvIII was not associated with TTP or OS. The presence of HPV DNA (38%), p16 immunostaining (32%), c-MET high expression (58%) and EGFR amplification (27%), were not associated with response, TTP or OS.

Conclusion

EGFRvIII mutation, present in about 40% of SCCHN, appears to be an unexpected prognostic biomarker associated with better disease control in R/M SCCHN regardless of treatment with erlotinib. Larger prospective studies are required to validate its significance.

A pediatric phase I trial and pharmacokinetic study of ispinesib: a Children's Oncology Group phase I consortium study

PURPOSE

To determine the maximum-tolerated dose, dose-limiting toxicities, and pharmacokinetics of the kinesin spindle protein inhibitor ispinesib in pediatric patients with recurrent or refractory solid tumors.

SUBJECTS AND METHODS

Ispinesib was administered as 1-hr intravenous infusion weekly × 3, every 28 days. Cohorts of 3-6 patients were enrolled at 5, 7, 9, and 12 mg/m(2) /dose. Serial plasma samples for pharmacokinetic analyses were obtained after the first dose.

RESULTS

Twenty-four (13 females) patients with a median (range) age of 10 years (1-19) were enrolled in the study. At the 12 mg/m(2) dose level dose-limiting neutropenia occurred in 2/6 patients and hyperbilirubinemia in 1/6 patients, while at the 9 mg/m(2) dose level 1/6 patients had dose-limiting neutropenia. There were no objective responses, but three patients (diagnoses of anaplastic astrocytoma, alveolar soft part sarcoma, and ependymoblastoma) had stable disease for 4-7 courses. There was substantial interpatient variation in drug disposition. The median (range) terminal elimination half-life was 16 (8-44) hr and the plasma drug clearance was 5 (1-14) L/hr/m(2) .

CONCLUSIONS

The maximum tolerated and recommended phase II dose for ispinesib administered weekly × 3 every 28 days for children with solid tumors is 9 mg/m(2) /dose. Plans for a phase II trial in select pediatric solid tumors are in development.

Microtubule-binding agents: a dynamic field of cancer therapeutics

Microtubules are dynamic filamentous cytoskeletal proteins composed of tubulin and are an important therapeutic target in tumour cells. Agents that bind to microtubules have been part of the pharmacopoeia of anticancer therapy for decades and until the advent of targeted therapy, microtubules were the only alternative to DNA as a therapeutic target in cancer. The screening of a range of botanical species and marine organisms has yielded promising new antitubulin agents with novel properties. In the current search for novel microtubule-binding agents, enhanced tumour specificity, reduced neurotoxicity and insensitivity to chemoresistance mechanisms are the three main objectives.

A phase I study of ispinesib, a kinesin spindle protein inhibitor, administered weekly for three consecutive weeks of a 28-day cycle in patients with solid tumors

PURPOSE

To establish the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, and pharmacokinetic profile of ispinesib when administered as a 1-h intravenous infusion weekly for three consecutive weeks of a 28 day treatment period to patients with advanced solid tumors.

EXPERIMENTAL DESIGN

Thirty patients were enrolled using an initial accelerated dose-escalation phase followed by a standard dose-escalation phase at doses ranging from 1-8 mg/m(2)/week. Pharmacokinetic samples, skin punch biopsies, and tumor biopsies (in patients with accessible tumor) were obtained during cycle 1 of treatment. Disease assessment was performed every two treatment cycles.

RESULTS

The MTD was defined as 7 mg/m(2) administered as a 1-h infusion weekly for three consecutive weeks of a 28 day schedule. The MTD was exceeded at 8 mg/m(2) due to DLTs of grade 2 (one patient) and grade 3 neutropenia (one patient) that resulted in the inability to administer the Day 15 dose in Cycle 1. The neutrophil nadir occurred at approximately Day 8 with a 3-7 day recovery period. The most common toxicities were nausea, diarrhea, fatigue, and neutropenia. Alopecia, mucositis, and neuropathy were not observed. Stable disease was reported as the best response to treatment in nine patients.

CONCLUSION

The recommended dose of ispinesib is 7 mg/m(2) over 1 h weekly for three consecutive weeks of a 28 day treatment cycle.

Activity of the kinesin spindle protein inhibitor ispinesib (SB-715992) in models of breast cancer

PURPOSE

Ispinesib (SB-715992) is a potent inhibitor of kinesin spindle protein, a kinesin motor protein essential for the formation of a bipolar mitotic spindle and cell cycle progression through mitosis. Clinical studies of ispinesib have shown a 9% response rate in patients with locally advanced or metastatic breast cancer and a favorable safety profile without significant neurotoxicities, gastrointestinal toxicities, or hair loss. To better understand the potential of ispinesib in the treatment of breast cancer, we explored the activity of ispinesib alone and in combination with several therapies approved for the treatment of breast cancer.

EXPERIMENTAL DESIGN

We measured the ispinesib sensitivity and pharmacodynamic response of breast cancer cell lines representative of various subtypes in vitro and as xenografts in vivo and tested the ability of ispinesib to enhance the antitumor activity of approved therapies.

RESULTS

In vitro, ispinesib displayed broad antiproliferative activity against a panel of 53 breast cell lines. In vivo, ispinesib produced regressions in each of five breast cancer models and tumor-free survivors in three of these models. The effects of ispinesib treatment on pharmacodynamic markers of mitosis and apoptosis were examined in vitro and in vivo, revealing a greater increase in both mitotic and apoptotic markers in the MDA-MB-468 model than in the less sensitive BT-474 model. In vivo, ispinesib enhanced the antitumor activity of trastuzumab, lapatinib, doxorubicin, and capecitabine and exhibited activity comparable with paclitaxel and ixabepilone.

CONCLUSIONS

These findings support further clinical exploration of kinesin spindle protein inhibitors for the treatment of breast cancer.

Initial testing (stage 1) of the kinesin spindle protein inhibitor ispinesib by the pediatric preclinical testing program

BACKGROUND

Ispinesib is a highly specific inhibitor of kinesin spindle protein (KSP, HsEg5), a mitotic kinesin required for separation of the spindle poles. Here we report the activity of ispinesib against the in vitro and in vivo panels of the Pediatric Preclinical Testing Program (PPTP).

PROCEDURES

Ispinesib was tested against the PPTP in vitro panel cell lines at concentrations from 0.1 nM to 1 microM and against the in vivo tumor panel xenografts by intraperitoneal administration (5 or 10 mg/kg) every 4 days for 3 doses repeated at day 21.

RESULTS

Ispinesib was highly potent against the PPTP's in vitro cell lines with a median IC(50) of 4.1 nM. Ispinesib (10 mg/kg) induced unexplained toxicity in mice bearing osteosarcoma xenografts and exceeded the MTD in 12 of 40 non-osteosarcoma xenografts. Ispinesib induced significant tumor growth delay in 88% (23/26) of evaluable xenografts. Using a time to event measure of efficacy, ispinesib had intermediate and high levels of activity against 4 (21%) and 5 (26%) of the 19 evaluable solid tumor xenografts, respectively. Ispinesib induced maintained complete responses (CR) in a rhabdoid tumor, a Wilms tumor and a Ewing sarcoma xenograft. Ispinesib (5 mg/kg) produced 2 complete and 2 partial responses among 6 evaluable xenografts in the ALL panel. The in vivo pattern of activity was distinctive from that previously reported for vincristine.

CONCLUSIONS

Ispinesib demonstrated broad in vivo antitumor activity, including maintained complete responses for several xenografts, although with high toxicity rates at the doses studied.

How do anti-mitotic drugs kill cancer cells?

In 2007, over 12-million people were diagnosed with cancer. According to the American Cancer Society, at least one third of these individuals are not expected to survive the disease, making cancer the second most prevalent cause of death worldwide. Systemic chemotherapy forms the mainstay of cancer treatment, and agents that disrupt mitotic spindle assembly - so called ;anti-mitotics' - are commonly used to treat a wide variety of cancers. Traditional anti-mitotic agents include the microtubule toxins such as taxol, other taxanes and the vinca alkaloids, all of which have proven successful in the clinic. However, patient response remains highly unpredictable, and drug resistance is common. In addition, toxicity is a problem. To address these limitations, a new generation of anti-mitotic drugs is being developed. As the first wave of these new agents enters clinical trails, much hope rests on their outcome. Meanwhile, significant attention is being focused on trying to predict which tumour types are likely to respond. In this Commentary, we outline recent advances in our understanding of how cancer cells respond to anti-mitotic drugs, and discuss the relevance of these studies to their use in the clinic.

Centrosomes and cancer: how cancer cells divide with too many centrosomes

Precise control of centrosome number is crucial for bipolar spindle assembly and accurate transmission of genetic material to daughter cells. Failure to properly control centrosome number results in supernumerary centrosomes, which are frequently found in cancer cells. This presents a paradox: during mitosis, cells with more than two centrosomes are prone to multipolar mitoses and cell death, however, cancer cells possessing extra centrosomes usually divide successfully. One mechanism frequently utilized by cancer cells to escape death caused by multipolar mitoses is the clustering of supernumerary centrosomes into bipolar arrays. An understanding of the molecular mechanisms by which cancer cells can suppress multipolar mitoses is beginning to emerge. Here, we review what's currently known about centrosome clustering mechanisms and discuss potential strategies to target these mechanisms for the selective killing of cancer cells.

Mitotic drivers--inhibitors of the Aurora B Kinase

In this article we review the basis for current anti-mitotic, anti-cancer, therapy and the potential for Aurora B kinase inhibitors as a new differentiated class of agents--"mitotic drivers". We review the current understanding of Aurora B inhibition from basic cell biology to inhibitors currently undergoing clinical trials.

Targeting the kinesin spindle protein: basic principles and clinical implications

Kinesin spindle protein (KSP), a member of the kinesin superfamily of microtubule-based motors, plays a critical role in mitosis as it mediates centrosome separation and bipolar spindle assembly and maintenance. Inhibition of KSP function leads to cell cycle arrest at mitosis with the formation of monoastral microtubule arrays, and ultimately, to cell death. Several KSP inhibitors are currently being studied in clinical trials and provide new opportunities for the development of novel anticancer therapeutics alternative from the available microtubule targeting drugs.

Cancer cells display profound intra- and interline variation following prolonged exposure to antimitotic drugs

Drugs targeting the mitotic spindle are used extensively during chemotherapy, but surprisingly, little is known about how they kill tumor cells. This is largely because many of the population-based approaches are indirect and lead to vague and confusing interpretations. Here, we use a high-throughput automated time-lapse light microscopy approach to systematically analyze over 10,000 single cells from 15 cell lines in response to three different classes of antimitotic drug. We show that the variation in cell behavior is far greater than previously recognized, with cells within any given line exhibiting multiple fates. We present data supporting a model wherein cell fate is dictated by two competing networks, one involving caspase activation, the other protecting cyclin B1 from degradation.