All-trans-retinoic acid as induction or maintenance treatment improves disease-free and overall survival as compared with chemotherapy alone and should be included in the treatment of acute promyelocytic leukemia.

We previously reported a benefit for alltrans retinoic acid (ATRA) in both induction and maintenance therapy in patients with acute promyelocytic leukemia (APL). To determine the durability of this benefit and identify important prognostic factors, long-term follow-up of the North American Intergroup APL trial is reported. A total of 350 patients with newly diagnosed APL were randomized to either daunorubicin and cytarabine (DA) or ATRA for induction and then either ATRA maintenance or observation following consolidation chemotherapy. The complete remission (CR) rates were not significantly different between the ATRA and DA groups (70% and 73%, respectively). However, the 5-year disease-free survival (DFS) and overall survival (OS) were longer with ATRA than with DA for induction (69% vs 29% and 69% vs 45%, respectively). Based on both induction and maintenance randomizations, the 5-year DFS was 16% for patients randomized to DA and observation, 47% for DA and ATRA, 55% for ATRA and observation, and 74% for ATRA and ATRA. There was no advantage of either induction regimen among any subgroups when CR alone was con-

ObjectiveThis phase I clinical study (NCT01415297) evaluated the safety, tolerability, maximum-tolerated dose (MTD), pharmacokinetics and pharmacodynamics of IT-139 (formerly NKP-1339) monotherapy in patients with advanced solid tumours. IT-139, sodium trans-(tetrachlorobis(1H-indazole)ruthenate(III)), is a novel small molecule that suppresses the stress induction of GRP78 in tumour cells. GRP78 is a key regulator of misfolded protein processing, and its upregulation in tumours is associated with intrinsic and drug-induced resistance.MethodsForty-six patients with advanced solid tumours refractory to treatment received intravenous infusions of IT-139 on days 1, 8 and 15 for every 28 days, and doses were evaluated across nine cohorts at 20, 40, 80, 160, 320, 420, 500, 625 and 780 mg/m2.ResultsOverall, IT-139 was well tolerated. The treatment-emergent adverse events (AEs) occurring in ≥20% of patients were nausea, fatigue, vomiting, anaemia and dehydration. The majority of patients had AEs that were ≤grade 2, regardless of relationship with the study drug. Of the total 38 efficacy-evaluable patients, one patient with a carcinoid tumour achieved a durable partial response. Nine additional patients achieved stable disease . The MTD was determined to be 625 mg/m2. IT-139 exhibited first-order linear pharmacokinetics.ConclusionsIT-139 demonstrated a manageable safety profile at the MTD and modest anti-tumour activity in this study of patients with solid tumours refractory to treatment. The lack of dose-limiting haematological toxicity and the absence of neurotoxicity position IT-139 well for use in combination with a broad spectrum of anticancer drugs.Trial registration numberNCT01415297.

Human breast tumors harbor supernumerary centrosomes in almost 80% of tumor cells. Although amplified centrosomes compromise cell viability via multipolar spindles resulting in death-inducing aneuploidy, cancer cells tend to cluster extra centrosomes during mitosis. As a result cancer cells display bipolar spindle phenotypes to maintain a tolerable level of aneuploidy, an edge to their survival. HSET/KifC1, a kinesin-like minus-end directed microtubule motor has recently found fame as a crucial centrosome clustering molecule. Here we show that HSET promotes tumor progression via mechanisms independent of centrosome clustering. We found that HSET is overexpressed in breast carcinomas wherein nuclear HSET accumulation correlated with histological grade and predicted poor progression-free and overall survival. In addition, deregulated HSET protein expression was associated with gene amplification and/or translocation. Our data provide compelling evidence that HSET overexpression is pro-proliferative, promotes clonogenic-survival and enhances cell-cycle kinetics through G2 and M-phases. Importantly, HSET co-immunoprecipitates with survivin, and its overexpression protects survivin from proteasome-mediated degradation, resulting in its increased steady-state levels. We provide the first evidence of centrosome clustering-independent activities of HSET that fuel tumor progression and firmly establish that HSET can serve both as a potential prognostic biomarker and as a valuable cancer-selective therapeutic target.

Nearly a century ago, cell biologists postulated that the chromosomal aberrations blighting cancer cells might be caused by a mysterious organelle-the centrosome-that had only just been discovered. For years, however, this enigmatic structure was neglected in oncologic investigations and has only recently reemerged as a key suspect in tumorigenesis. A majority of cancer cells, unlike healthy cells, possess an amplified centrosome complement, which they manage to coalesce neatly at two spindle poles during mitosis. This clustering mechanism permits the cell to form a pseudo-bipolar mitotic spindle for segregation of sister chromatids. On rare occasions this mechanism fails, resulting in declustered centrosomes and the assembly of a multipolar spindle. Spindle multipolarity consigns the cell to an almost certain fate of mitotic arrest or death. The catastrophic nature of multipolarity has attracted efforts to develop drugs that can induce declustering in cancer cells. Such chemotherapeutics would theoretically spare healthy cells, whose normal centrosome complement should preclude multipolar spindle formation. In search of the 'Holy Grail' of nontoxic, cancer cell-selective, and superiorly efficacious chemotherapy, research is underway to elucidate the underpinnings of centrosome clustering mechanisms. Here, we detail the progress made towards that end, highlighting seminal work and suggesting directions for future research, aimed at demystifying this riddling cellular tactic and exploiting it for chemotherapeutic purposes. We also propose a model to highlight the integral role of microtubule dynamicity and the delicate balance of forces on which cancer cells rely for effective centrosome clustering. Finally, we provide insights regarding how perturbation of this balance may pave an inroad for inducing lethal centrosome dispersal and death selectively in cancer cells.