Leadership Diversity and Development in the Nation's Cancer Centers.

The capacity and diversity of the oncology leadership workforce has not kept pace with the emerging needs of our increasingly complex cancer centers and the spectrum of challenges our institutions face in reducing the cancer burden in diverse catchment areas. Recognizing the importance of a diverse workforce to reduce cancer inequities, the Association of American Cancer Institutes conducted a survey of its 103 cancer centers to examine diversity in leadership roles from research program leaders to cancer center directors. A total of 82 (80%) centers responded, including 64 National Cancer Institute-designated and 18 emerging centers. Among these 82 respondents, non-Hispanic White individuals comprised 79% of center directors, 82% of deputy directors, 72% of associate directors, and 72% of program leaders. Women are underrepresented in all leadership roles (ranging from 16% for center directors to 45% for associate directors). Although the limited gender, ethnic, and racial diversity of center directors and perhaps deputy directors is less surprising, the demographics of current research program leaders and associate directors exposes a substantial lack of diversity in the traditional cancer center senior leadership pipeline. Sole reliance on the cohort of current center leaders and leadership pipeline is unlikely to produce the diversity in cancer center leadership needed to facilitate the ability of those centers to address the needs of the diverse populations they serve. Informed by these data, this commentary describes some best practices to build a pipeline of emerging leaders who are representative of the diverse populations served by these institutions and who are well positioned to succeed.

A phase I and pharmacodynamic study of fludarabine, carboplatin, and topotecan in patients with relapsed, refractory, or high-risk acute leukemia.

PURPOSE: A novel regimen designed to maximize antileukemia activity of carboplatin through inhibiting repair of platinum-DNA adducts was conducted in poor prognosis, acute leukemia patients. EXPERIMENTAL DESIGN: Patients received fludarabine (10 to 15 mg/m(2) x 5 days), carboplatin (area under the curve 10 to 12 by continuous infusion over 5 days), followed by escalated doses of topotecan infused over 72 hours (fludarabine, carboplatin, topotecan regimen). Twenty-eight patients had acute myelogenous leukemia (7 untreated secondary acute myelogenous leukemia, 11 in first relapse, and 10 in second relapse or refractory), 1 patient had refractory/relapsed acute lymphoblastic leukemia, and 2 patients had untreated chronic myelogenous leukemia blast crisis. Six patients had failed an autologous stem cell transplant. Patients ranged from 19 to 76 (median 54) years. Measurement of platinum-DNA adducts were done in serial bone marrow specimens. RESULTS: Fifteen of 31 patients achieved bone marrow aplasia. Clinical responses included 2 complete response, 4 complete response with persistent thrombocytopenia, and 2 partial response. Prolonged myelosuppression was observed with median time to blood neutrophils >/=200/microl of 28 (0 to 43) days and time to platelets >/=20,000/microl (untransfused) of 40 (24 to 120) days. Grade 3 or greater infections occurred in all of the patients, and there were 2 infection-related deaths. The nonhematologic toxicity profile was acceptable. Five patients subsequently received allografts without early transplant-related mortality. Maximum tolerated dose of fludarabine, carboplatin, topotecan regimen was fludarabine 15 mg/m(2) x 5, carboplatin area under the curve 12, and topotecan 2.55 mg/m(2) over 72 hours. An increase in bone marrow, platinum-DNA adduct formation between the end of carboplatin infusion and 48 hours after the infusion correlated with bone marrow response. CONCLUSIONS: Fludarabine, carboplatin, topotecan regimen is a promising treatment based on potential pharmacodynamic interactions, which merits additional study in poor prognosis, acute leukemia patients.

A phase I and pharmacodynamic study of sequential topotecan and etoposide in patients with relapsed or refractory acute myelogenous and lymphoblastic leukemia.

We designed a pharmacokinetic and pharmacodynamic phase I study of sequential topotecan (2.55-6.3mg/m2) by 72h infusion followed by five daily doses of etoposide for patients with refractory acute leukemia based upon synergistic anti-tumor activity of topoisomerase I and II inhibitors in vitro. Eight of the 29 patients achieved bone marrow aplasia and two patients achieved clinical remission. Common grade 3-4 toxicities included hepatic and gastrointestinal dysfunction, and correlated with increased steady-state plasma topotecan concentration. The predicted up-regulation of topoisomerase II activity by topoisomerase I inhibition was not observed at this dose and schedule and may provide insight into the modest anti-leukemia activity of the regimen.

Down-regulation of topoisomerase II alpha is caused by up-regulation of GRP78.

Glucose-regulated protein of M(r) 78kDa (GRP78) is a resident protein of endoplasmic reticulum (ER). We have previously shown that the cells become resistant to topoisomerase II alpha (topo II alpha) targeted cancer chemotherapeutic drug such as etoposide (VP-16) when GRP78 is up-regulated by various means. Up-regulation of GRP78 in V79 Chinese hamster cell lines was achieved by treating the cells with NAD antagonist 6-aminonicotinamide (6AN), inhibitor of glucose metabolism such as 2-deoxyglucose (2dG). Further, up-regulation of GRP78 was also observed in V79-derived cell lines which are deficient in poly(ADP-ribose) polymerase (PARP1) metabolism. However, mechanisms of association of GRP78 up-regulation and resistance to VP-16 remained obscured under the conditions outlined above. In the manuscript, using various methods, we demonstrate, for the first time, that up-regulation of GRP78, using approaches depicted above, causes down-regulation of topo II alpha and its activity. We have also discussed the clinical implications of our findings.

Interference with topoisomerase IIalpha potentiates melphalan cytotoxicity.

We studied the consequences of interfering with DNA topoisomerase IIalpha (topo IIalpha) activity on melphalan-induced cytotoxicity. In order to accomplish our goal we used three different approaches to interfere with topo IIalpha. These include: i) use of three V79 Chinese hamster lung fibroblast-derived mutant cell lines, V507, V511, and V513 that are dysfunctional in topo IIalpha activity; ii) treatment of cells with etoposide (VP-16) which inhibits topo IIalpha through the formation of DNA-enzyme cleavable complex; and iii) exposure of cells to merbarone or ICRF-187 (Zinecard) that inhibits the activity of topo IIalpha by restricting its access to DNA. Based on clonogenic survival assays, all three approaches resulted in a significant potentiation of cytotoxicity of melphalan suggesting that topo IIalpha plays an important role in processing of DNA damage induced by melphalan. Furthermore, using alkaline elution assay, we show that melphalan-induced DNA cross-link formation and its repair is faster in V511 cells compared to the parental V79 cells. However, melphalan-induced sister chromatid exchanges (SCE) are found to be significantly higher in V511 cells compared to V79 cells. In addition, we find an excellent correlation between melphalan-induced SCE and cytotoxicity. These results could be explained on the assumption that topo IIalpha plays an important role in damage processing through excision repair of melphalan-induced DNA cross-links. However, in the absence of topo IIalpha the damages are primarily processed by recombination repair which may be prone to deleterious genetic alterations resulting in increased lethality as the frequency of recombination increases. In summary, our results demonstrate that: i) topo IIalpha deficiency is associated with increased sensitivity to melphalan; ii) deficiency of topo IIalpha is associated with an increase in melphalan-induced SCE; iii) increase in melphalan-induced SCE is associated with an increase in cytotoxicity; and iv) downregulation of topo IIalpha may be a useful approach to modulate the cytotoxicity of melphalan in combination chemotherapy regimens. These results have several important clinical implications. First, interference with topo IIalpha using agents such as VP-16 or ICRF-187 may provide a useful approach to enhance the efficacy of melphalan in combination chemotherapy regimens. Second, tumors which develop resistance to topo IIalpha-directed drugs due to quantitative or qualitative alterations in topo IIalpha may show increased susceptibility to a chemotherapy regimen containing melphalan.