Faculty Bibliography

The extent of tumor reduction from neoadjuvant chemotherapy for breast cancer correlates with outcome. We investigated whether the initial cellular responses to paclitaxel are related to the extent of tumor reduction. Eleven women with breast cancer received paclitaxel (every 2 weeks for 4 cycles) as neoadjuvant treatment. Serial fine-needle aspirations (FNA; 25-gauge, 1 pass) were obtained before treatment and at 24, 48, 72, and 96 h after the first paclitaxel dose. Microscopic counts of apoptotic and mitotic indices were performed. The change in cancer volume from treatment was determined using radiological measurements with allowance for change in the histopathological amount of cancer. Apoptotic and mitotic responses usually subsided within 4 days. The duration of the initial apoptotic response was different for women with different treatment results. Cumulative apoptotic response for the first 4 days inversely correlated with the proportion of residual cancer after neoadjuvant treatment. FNA is a versatile clinical method to obtain breast cancer cells for therapy response studies. Apoptotic response to the first dose of paclitaxel is almost complete within 4 days, implying that more frequent (weekly) paclitaxel dosing might be beneficial. The apoptotic response to the first dose of paclitaxel appeared to predict the amount of cancer reduction from this treatment. This is a promising start toward the development of an early chemopredictive assay for paclitaxel treatment of breast cancer

The i.p. administration of topoisomerase I (Topo I) inhibitors has a pharmacologic advantage over intravenous application, including preservation of the biologically active lactone form. In our ongoing study, patients have received 9-amino-20(S)-camptothecin (9-AC) i.p. on days 1, 3, 5, 8, 10, and 12, repeated every 4 weeks. The daily dose has been escalated to level IV of 1.5 mg/m2 (9.0 mg/m2 per course), median of 3 cycles, range 1-4, with a reversible Grade 3 neutropenia in one patient. Responses included one CR (resolution of a pleural effusion), two patients without progressive disease (PD), two not evaluable, and two patients too early for evaluation. The area under the curve (AUC)i.p./AUCpl ratio (pharmacologic advantage) ranged from 7.6 to 16.5 on average, and, using nonlinear modeling, the pharmacologic decay data were fit to one- or two-compartmental models. Overall, a 9-AC i.p. application is well tolerated and anticipated to be an active regimen against i.p. malignancies, particularly those known to be sensitive to systemic Topo-I inhibitors

PURPOSE: This was a phase I study of AG 331 to determine systemic tolerance and pharmacokinetics following single and multiple escalating intravenous doses. METHODS: The study was an open-label phase I trial that was divided into two components. In phase IA (single dose), six dose levels from 12.5 to 225 mg/m2 were administered to 18 patients (3 at each dose level) and serial blood samples were collected for 72 h. Upon achieving satisfactory pharmacologic parameters, the multiple dosing component (phase IB) was initiated. Six dose levels from 50 to 800 mg/m2 per day were administered for 5 consecutive days to 18 patients. Pre- and postdose blood samples were obtained on days 1-4 and serial blood samples were collected over 24 h following dose 5. Nonhematologic and hepatic toxicities were assessed, serum AG 331 concentrations were measured and pharmacokinetic parameters determined. RESULTS: Other than fatigue, no severe toxicities were encountered in phase IA. Liver toxicity was manifested by elevations in transaminase first noted at multiple doses of 200 mg/m2 per day for 5 days. Fever and malaise but no myelosuppression were noted. The mean terminal t1/2 following single doses was significantly shorter than the t1/2 following multiple dosing (6.8 vs 9.9 h) and clearance was significantly faster following single doses than following multiple dosing (81.7 vs 30.4 l/h), but no significant difference in Vd was noted. CONCLUSIONS: The dose-related toxicity profile precludes further clinical development at this time. The pharmacokinetics of AG 331 following single and multiple doses showed significant differences.

P-glycoprotein (Pgp)-associated multidrug resistance (MDR) is related to intrinsic and acquired cross resistance to anthracyclines, vinca alkaloids, and other antineoplastic antibiotics. Expression of MDR1 is widely considered to play an important role in conferring resistance to adjuvant chemotherapy in women with breast tumor cells in women with disseminated disease, although data supporting this view is, at best, conflicting. The expression of MDR1 gene and its gene product, P-glycoprotein, was investigated in primary and advanced breast cancers (both previously untreated and previously treated on specific treatment protocols) to assess the role of P-glycoprotein in determining responsiveness to adjuvant chemotherapy. Expression was assessed by immunohistochemistry, reverse transcription-PCR (RT-PCR), Northern Blot and Western Blot. MDR1 mRNA was detected in 40% of the breast cancers tested by RT-PCR with 40 cycles of PCR amplification. When reducing the PCR amplification cycles to 28, the MDR1 gene expression signal disappeared from breast cancers of the highest expressers; however, known MDR1 positive control normal tissues, such as adrenal, kidney, and liver continued to show an expression product. Western and Northern blots failed to demonstrate the MDR1 gene product, P-glycoprotein, in these breast cancers. In contrast, physiologic levels of P-glycoprotein was clearly detected in normal adrenal, kidney, and liver by these techniques. Immunohistochemistry confirmed that breast carcinoma cells lacked P-glycoprotein expression; however, interstitial mononuclear cells, morphologically consistent with lymphocytes or macrophages did show immunostaining in some of these breast tumors. MDR1 gene expression identified by RT-PCR was not correlated either with response to paclitaxel therapy (29 patients able to be evaluated, p = 0.34, Fisher Exact Test) or overall survival (32 breast cancer patients with clinical follow-up information, p = 0.336, log rank). In conclusion, P-glycoprotein was not expressed in breast carcinoma cells at significant levels, although it was expressed in stomal lymphocytes or macrophages. These results suggest that P-glycoprotein does not play a significant role in multidrug resistance of breast cancer