Androgen receptors beyond prostate cancer: an old marker as a new target

Androgen receptors (ARs) play a critical role in the development of prostate cancer. Targeting ARs results in important salutary effects in this malignancy. Despite mounting evidence that ARs also participate in the pathogenesis and/or progression of diverse tumors, exploring the impact of hormonal manipulation of these receptors has not been widely pursued beyond prostate cancer. This review describes patterns of AR expression in a spectrum of cancers, and the potential to exploit this knowledge in the clinical therapeutic setting.

New drugs and novel mechanisms of action in multiple myeloma in 2013: a report from the International Myeloma Working Group (IMWG)

Treatment in medical oncology is gradually shifting from the use of nonspecific chemotherapeutic agents toward an era of novel targeted therapy in which drugs and their combinations target specific aspects of the biology of tumor cells. Multiple myeloma (MM) has become one of the best examples in this regard, reflected in the identification of new pathogenic mechanisms, together with the development of novel drugs that are being explored from the preclinical setting to the early phases of clinical development. We review the biological rationale for the use of the most important new agents for treating MM and summarize their clinical activity in an increasingly busy field. First, we discuss data from already approved and active agents (including second- and third-generation proteasome inhibitors (PIs), immunomodulatory agents and alkylators). Next, we focus on agents with novel mechanisms of action, such as monoclonal antibodies (MoAbs), cell cycle-specific drugs, deacetylase inhibitors, agents acting on the unfolded protein response, signaling transduction pathway inhibitors and kinase inhibitors. Among this plethora of new agents or mechanisms, some are specially promising: anti-CD38 MoAb, such as daratumumab, are the first antibodies with clinical activity as single agents in MM. Moreover, the kinesin spindle protein inhibitor Arry-520 is effective in monotherapy as well as in combination with dexamethasone in heavily pretreated patients. Immunotherapy against MM is also being explored, and probably the most attractive example of this approach is the combination of the anti-CS1 MoAb elotuzumab with lenalidomide and dexamethasone, which has produced exciting results in the relapsed/refractory setting.

Insulin growth factor-receptor (IGF-1R) antibody cixutumumab combined with the mTOR inhibitor temsirolimus in patients with refractory Ewing's sarcoma family tumors

PURPOSE

Temsirolimus was combined with cixutumumab, a fully human IgG1 monoclonal antibody directed at the insulin growth factor-1 receptor (IGF-1R).

EXPERIMENTAL DESIGN

Patients received cixutumumab, 6 mg/kg i.v. weekly, and temsirolimus, 25 to 37.5 mg i.v. weekly (4-week cycles), with restaging after 8 weeks. Median follow-up was 8.9 months.

RESULTS

Twenty patients [17 with Ewing's sarcoma (EWS), 3 with desmoplastic small-round cell tumor (DSRCT)] were enrolled. Twelve patients (60%) were men with a median age of 24 years and six median prior systemic therapies in a metastatic setting. The most frequent toxicities were thrombocytopenia (85%), mucositis (80%), hypercholesterolemia (75%), hypertriglyceridemia (70%), and hyperglycemia (65%; mostly grade I-II). Seven of 20 patients (35%) achieved stable disease (SD) for more than 5 months or complete/partial (CR/PR) responses. Tumor regression of more than 20% (23%, 23%, 27%, 100%, 100%) occurred in five of 17 (29%) patients with EWS, and they remained on study for 8 to 27 months. One of six patients with EWS who previously developed resistance to a different IGF-1R inhibitor antibody achieved a CR. Four of the seven best responders developed grade III mucositis, myelosuppression, or hyperglycemia, which were controlled while maintaining drug dose.

CONCLUSION

Cixutumumab combined with temsirolimus was well-tolerated and showed preliminary evidence of durable antitumor activity in heavily pretreated EWS family tumors.

Development of cell-cycle inhibitors for cancer therapy

The cell cycle governs the transition from quiescence through cell growth to proliferation. The key parts of the cell cycle machinery are the cyclin-dependent kinases (CDKS) and the regulatory proteins called cyclins. The CDKS are rational targets for cancer therapy because their expression in cancer cells is often aberrant and their inhibition can induce cell death. Inhibitors of CDKS can also block transcription.Several drugs targeting the cell cycle have entered clinical trials. These agents include flavopiridol, indisulam, AZD5438, SNS-032, bryostatin-1, seliciclib, PD 0332991, and SCH 727965. Phase i studies have demonstrated that these drugs can generally be administered safely. Phase ii studies have shown little single-agent activity in solid tumors, but combination studies with cytotoxic chemotherapy have been more promising. In hematologic malignancies, reports have shown encouraging single-agent and combination activity. Pharmacodynamic studies show that the dose and schedule of these drugs are crucial to permit maximum therapeutic effect.

Cell-based therapy in ischemic stroke

Cell-based therapy for stroke represents a third wave of therapeutics for stroke and one focused on restorative processes with a longer time window of opportunity than neuroprotective therapies. An early time window, within the first week after stroke, is an opportunity for intravenously delivered bone marrow and perinatally derived cells that can home to areas of tissue injury and target brain remodeling. Allogeneic cells will likely be the most scalable and commercially viable product. Later time windows, months after stroke, may be opportunities for intracerebral transplantation of neuronally differentiated cell types. An integrated approach of cell-based therapy with early-phase clinical trials and continued preclinical work with focus on mechanisms of action is needed.

Pharmacokinetics and bioavailability of oral 5'-deoxy-5-fluorouridine in cancer patients

AIMS

Oral administration of 5-fluorouracil (FUra), an important cytotoxic agent, is limited by a wide variation in bioavailability. 5'-deoxy-5-fluorouridine (dFUrd), a masked form of FUra, has shown promise clinically when given intravenously or orally as a solution or tablet. This study investigates the efficacy of an oral capsule formulation of dFUrd in generating continuous systemic levels of this compound in cancer patients.

METHODS

Six patients with advanced intestinal or ovarian malignancies were given three cycles of dFUrd, days 1-5, at intervals of 4 weeks. The doses of dFUrd were 600 mg m-2 three times daily, 800 mg m-2 three times daily, and 1000 mg m-2 three times daily, on cycles one, two and three, respectively (total dose 36 g m-2 ). The initial dose in each cycle was given as a slow intravenous injection over 10 min, and the remainder orally. Plasma and urine levels of dFUrd and two of its metabolites, FUra and 5,6-dihydro-5-fluorouracil (FUraH2 ), were monitored in six patients at each dose level.

RESULTS

All six patients completed the study, receiving three different doses over a 3 month period, following which one had achieved a partial response, one had stable disease, and four had developed progressive disease. Side-effects were negligible, and only two instances of transient diarrhoea WHO grade 1 were seen. Total body clearance (CLtot) of intravenous dFUrd decreased with increasing dose; 2.7, 2.0 and 1.3 l min-1 m-2, following doses of 600, 800 and 1000 mg m-2, respectively. The mean elimination half-life of intravenous dFUrd increased with the dose from 15 to 22 min. Oral dFUrd was rapidly absorbed with a lag time of less than 20 min. The mean elimination half-life (t1/2, z ) of oral dFUrd was 32-45 min in the dose range 600-1000 mg m-2. The AUC of FUra and FUraH2 increased overproportionally with increasing intravenous doses of dFUrd. The mean systemic bioavailability of oral dFUrd was 34-47%.

CONCLUSIONS

dFUrd, which selectively releases the antimetabolite FUra in tumour cells, can be given orally at doses of 600-1000 mg m-2 three times daily for 5 days. The systemic levels achieved are equivalent to those seen following continuous infusions of dFUrd or FUra. Toxicity is tolerable, and further clinical investigation of oral dFUrd is warranted.