Notable response of a young adult with recurrent glioblastoma multiforme to vincristine-irinotecan-temozolomide and bevacizumab

Vincristine promotes differential levels of apoptosis, mitotic catastrophe, and senescence depending on the genetic background of glioblastoma cells

Vincristine (VCR) is a classical chemotherapeutic that has been revisited to treat refractory solid tumors producing encouraging results. VCR binds to tubulin and decreases the rate of microtubule dynamics, thus triggering many cellular responses and behaviors. However, the dynamics of these responses and fates are uncharacterized. This study combined systems biology approaches with acute and long-term in vitro experiments to predict key pathways and mechanisms associated with cell fates during and after VCR treatment. Glioblastoma (GBM) cells were treated with clinically relevant doses of VCR, and interconnected cell fates were explored. A correlation matrix based on experimental cell analysis reported strong negative correlations between cell number, nuclear irregularities, senescence, or apoptosis, depending on the cells' genetic makeup and treatment regimen. P53 would be essential in all analyzed processes according to topological network analysis. Furthermore, despite the high acute sensitivity, both cell lines re-growth in the long term after a single VCR treatment, especially in those populations with high levels of autophagy. These multiple responses may also be triggered in patients' exposed tumors, which should be considered to allow the rational design of VCR protocols, including modulators of the cell fates and pathways mentioned above.

A phase I study of irinotecan and temozolomide with bevacizumab in children with recurrent/refractory central nervous system tumors

PURPOSE

Children with relapsed/refractory central nervous system (CNS) tumors require novel combinations of therapies. Irinotecan and temozolomide (IT) is a frequently used therapy with an established toxicity profile. Bevacizumab is an anti-VEGF monoclonal antibody with demonstrated activity in CNS tumors. Therefore, the combination of these agents has therapeutic potential in CNS tumors. The objective of this study was to determine the maximum tolerated dose (MTD) of escalating dose IT combined with a fixed dose of bevacizumab (BIT) in children with relapsed/refractory CNS tumors.

METHODS

A phase I trial was performed in a 3 + 3 design. Therapy toxicities and radiologic responses to treatment were described.

RESULTS

One hundred eighty cycles of therapy were administered to 26 patients. The MTD of BIT was dose level 1, (bevacizumab 10 mg/kg on days 1 and 15, irinotecan 125 mg/m² on days 1 and 15, and temozolomide 125 mg/m² on days 1-5 of 28-day cycles). The regimen was well tolerated with primarily hematologic toxicity, which was not dose limiting. Among 22 response-evaluable patients, there was 1 complete response (CR), 6 partial responses (PR), and 10 stable diseases (SD) with an overall response rate (ORR: CR + PR) of 31.8%.

CONCLUSION

At the MTD, BIT therapy was well tolerated, and prolonged treatment courses of up to 24 cycles were feasible, with radiographic responses observed. Further evaluation is needed for efficacy in a phase II trial (NCT00876993, registered April 7, 2009, www.

CLINICALTRIALS

gov ).

Vincristine in Combination Therapy of Cancer: Emerging Trends in Clinics

Treatment of blood malignancies and other cancer diseases has been mostly unfeasible, so far. Therefore, novel treatment regimens should be developed and the currently used ones should be further elaborated. A stable component in various cancer treatment regimens consists of vincristine, an antimitotic compound of natural origin. Despite its strong anticancer activity, mostly, it cannot be administered as monotherapy due to its unspecific action and severe side effects. However, vincristine is suitable for combination therapy. Multidrug treatment regimens including vincristine are standardly applied in the therapy of non-Hodgkin lymphoma and other malignancies, in which it is combined with drugs of different mechanisms of action, mainly with DNA-interacting compounds (for example cyclophosphamide), or drugs interfering with DNA synthesis (for example methotrexate). Besides, co-administration of vincristine with monoclonal antibodies has also emerged, the typical example of which is the anti-CD20 antibody rituximab. Although in some combination anticancer therapies, vincristine has been replaced with other drugs exhibiting lesser side effects, though, in most cases, it is still irreplaceable. This is strongly evidenced by the number of active clinical trials evaluating vincristine in combination cancer therapy. Therefore, in this article, we have reviewed the most common cancer treatment regimens employing vincristine and bring an overview of current trends in the clinical development of this compound.