Edward M. Newman

Phase II Study of Vorinostat for Treatment of Relapsed or Refractory Indolent Non-Hodgkin's Lymphoma and Mantle Cell Lymphoma

PURPOSE We performed a phase II study of oral vorinostat, a histone and protein deacetylase inhibitor, to examine its efficacy and tolerability in patients with relapsed/refractory indolent lymphoma. PATIENTS AND METHODS In this open label phase II study (NCT00253630), patients with relapsed/refractory follicular lymphoma (FL), marginal zone lymphoma (MZL), or mantle cell lymphoma (MCL), with ≤ 4 prior therapies were eligible. Oral vorinostat was administered at a dose of 200 mg twice daily on days 1 through 14 of a 21-day cycle until progression or unacceptable toxicity. The primary end point was objective response rate (ORR), with secondary end points of progression-free survival (PFS), time to progression, duration of response, safety, and tolerability. RESULTS All 35 eligible patients were evaluable for response. The median number of vorinostat cycles received was nine. ORR was 29% (five complete responses [CR] and five partial responses [PR]). For 17 patients with FL, ORR was 47% (four CR, four PR). There were two of nine responders with MZL (one CR, one PR), and no formal responders among the nine patients with MCL, although one patient maintained stable disease for 26 months. Median PFS was 15.6 months for patients with FL, 5.9 months for MCL, and 18.8 months for MZL. The drug was well-tolerated over long periods of treatment, with the most common grade 3 adverse events being thrombocytopenia, anemia, leucopenia, and fatigue. CONCLUSION Oral vorinostat is a promising agent in FL and MZL, with an acceptable safety profile. Further studies in combination with other active agents in this setting are warranted.

A Phase I Study of Veliparib in Combination with Metronomic Cyclophosphamide in Adults with Refractory Solid Tumors and Lymphomas

Purpose: Oral administration of the alkylating agent cyclophosphamide at low doses, metronomic dosing, is well tolerated, with efficacy in multiple tumor types. PARP inhibition potentiates effects of cyclophosphamide in preclinical models. We conducted a phase I trial of the PARP inhibitor veliparib and metronomic cyclophosphamide in patients with refractory solid tumors and lymphoid malignancies. Experimental Design: Objectives were to establish the safety and maximum tolerated dose (MTD) of the combination; characterize veliparib pharmacokinetics (PK); measure poly(ADP-ribose) (PAR), a product of PARP, in tumor biopsies and peripheral blood mononuclear cells (PBMC); and measure the DNA-damage marker γH2AX in PBMCs and circulating tumor cells (CTC). Cyclophosphamide was administered once daily in 21-day cycles in combination with veliparib administered once daily for 7, 14, or 21 days. Results: Thirty-five patients were enrolled. The study treatment was well tolerated, and the MTD was established as veliparib 60 mg with cyclophosphamide 50 mg given once daily. Seven patients had partial responses; an additional six patients had disease stabilization for at least six cycles. PAR was significantly decreased in PBMCs (by at least 50%) and tumor biopsies (by at least 80%) across dose levels (DL); γH2AX levels were increased in CTCs from seven of nine patients evaluated after drug administration. Conclusions: The combination of veliparib with metronomic cyclophosphamide is well tolerated and shows promising activity in a subset of patients with BRCA mutations. A phase II trial of the combination compared with single-agent cyclophosphamide is ongoing in BRCA-positive ovarian cancer, triple-negative breast cancer, and low-grade lymphoma. Clin Cancer Res; 18(6); 1726–34. ©2012 AACR.

Refractory metastatic breast cancer: salvage therapy with fluorouracil and high-dose continuous infusion leucovorin calcium.

Sixty women with metastatic breast cancer refractory to at least one chemotherapeutic regimen were treated with fluorouracil (FUra) and high-dose continuous infusion folinic acid (leucovorin calcium). One complete remission lasting 8.7 months and nine partial remissions ranging in duration from 1.3 to 12.8 months were observed, for an objective response rate of 17% (95% confidence interval for response, 8% to 27%). Nine of the ten responding patients had metastatic disease that had objectively progressed on previous chemotherapy with a FUra-containing regimen. This program was well tolerated, with toxicities consisting mainly of stomatitis and granulocytopenia. These results suggest that augmentation of the reduced folate levels of metastatic breast carcinomas may enhance the effectiveness of the fluoropyrimidines in this disease.

Pharmacokinetics and toxicity of high-dose intravenous methotrexate in the treatment of leptomeningeal carcinomatosis

Purpose: To evaluate the pharmacokinetics and toxicity of high-dose intravenous (i.v.) methotrexate (MTX) with leucovorin in patients with meningeal carcinomatosis. Methods: Of 16 eligible patients entered on this study, 13 with meningeal carcinomatosis from breast cancer, lung cancer, or osteosarcoma were treated with MTX at loading doses of 200–1500 mg/m2, followed by a 23-h infusion of 800–6000 mg/m2. Three patients without meningeal disease were also treated and the cerebrospinal fluid (CSF) MTX concentrations were compared in patients with and without central nervous system (CNS) disease. Results: Patients without CNS disease had lower CSF MTX concentrations relative to the plasma MTX levels than those with CNS disease, who all had CSF MTX concentrations above the target cytotoxic concentration (1 μM). The CSF MTX concentrations correlated better with the free and the total plasma MTX concentrations than with the doses. The mean half-life of CSF MTX was 8.7 ± 3.4 h. The mean plasma clearance of MTX was not significantly different in patients with CNS disease (84 ± 41 ml/min per m2) versus without CNS disease (59 ± 38 ml/min per m2). All toxicities were grade 2 or less except grade 3 hematologic toxicity. No patient had an objective response in the CSF. Conclusion: This trial demonstrates that potentially cytotoxic CSF MTX concentrations (>1 μM) are delivered safely by i.v. infusion, a less invasive and better distributed CSF therapy compared with intrathecal MTX. Because of the excellent pharmacokinetics and toxicity, high-dose i.v. MTX should be evaluated at a loading dose of 700 mg/m2 and a 23-h infusion of 2800 mg/m2 with leucovorin in less heavily pretreated patients with carcinomatous meningitis.

Microbiological analysis of 5-formyltetrahydrofolic acid and other folates using an automatic 96-well plate reader☆

The growth of auxotrophic bacteria remains the method of choice for the determination of biologically active folate metabolites in plasma. This report describes a microbiological assay for folates adapted to use disposable 96-well plates and an automatic plate reader. The modifications in the assay decreased reagent costs and made the analysis of hundreds of samples per day possible with a sensitivity limit of 10 fmol of (6S)-5-formyltetrahydrofolic acid. This limit compares favorably with that of previously reported, more laborious methods. The unnatural 6R diastereomer of 5-formyltetrahydrofolic acid did not interfere with the microbiological assay of the natural 6S diastereomer.

CD30 downregulation, MMAE resistance, and MDR1 upregulation are all associated with resistance to brentuximab vedotin

Brentuximab vedotin (BV) is an antibody–drug conjugate that specifically delivers the potent cytotoxic drug monomethyl auristatin E (MMAE) to CD30-positive cells. BV is FDA approved for treatment of relapsed/refractory Hodgkin lymphoma and anaplastic large cell lymphoma (ALCL); however, many patients do not achieve complete remission and develop BV-resistant disease. We selected for BV-resistant Hodgkin lymphoma (L428) and ALCL (Karpas-299) cell lines using either constant (ALCL) or pulsatile (Hodgkin lymphoma) exposure to BV. We confirmed drug resistance by MTS assay and analyzed CD30 expression in resistant cells by flow cytometry, qRT-PCR, and Western blotting. We also measured drug exporter expression, MMAE resistance, and intracellular MMAE concentrations in BV-resistant cells. In addition, tissue biopsy samples from 10 Hodgkin lymphoma and 5 ALCL patients who had relapsed or progressed after BV treatment were analyzed by immunohistocytochemistry for CD30 expression. The resistant ALCL cell line, but not the Hodgkin lymphoma cell line, demonstrated downregulated CD30 expression compared with the parental cell line. In contrast, the Hodgkin lymphoma cell line, but not the ALCL cell line, exhibited MMAE resistance and increased expression of the MDR1 drug exporter compared with the parental line. For both Hodgkin lymphoma and ALCL, samples from patients relapsed/resistant on BV persistently expressed CD30 by immunohistocytochemistry. One Hodgkin lymphoma patient sample expressed MDR1 by immunohistocytochemistry. Although loss of CD30 expression is a possible mode of BV resistance in ALCL in vitro models, this has not been confirmed in patients. MMAE resistance and MDR1 expression are possible modes of BV resistance for Hodgkin lymphoma both in vitro and in patients. Mol Cancer Ther; 14(6); 1376–84. ©2015 AACR.

Pharmacokinetics of high‐dose etoposide

The pharmacokinetics of etoposide at doses of 1 gm/m2 to 3 gm/m2 were studied in patients with hematologic malignancies. The noncompartmental systemic clearance, mean residence time, steady‐state volume of distribution, and elimination half‐life were independent of the dose of etoposide, whereas the AUC was proportional to the dose. Comparison of these results with those reported previously indicates that etoposide exhibits linear pharmacokinetics over a thirtyfold range in doses (0.1 to 3 gm/m2).

Phase I Study of Pazopanib in Patients with Advanced Solid Tumors and Hepatic Dysfunction: A National Cancer Institute Organ Dysfunction Working Group Study

Purpose: Pazopanib is a potent, multitargeted receptor tyrosine kinase inhibitor; however, there is limited information regarding the effects of liver function on pazopanib metabolism and pharmacokinetics. The objective of this study was to establish the maximum-tolerated dose (MTD) and pharmacokinetic profile of pazopanib in patients with varying degrees of hepatic dysfunction. Experimental Design: Patients with any solid tumors or lymphoma were stratified into four groups based on the degree of hepatic dysfunction according to the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria. Pazopanib was given orally once a day on a 21-day cycle. A modified 3+3 design was used. Results: Ninety-eight patients were enrolled. Patients in the mild group tolerated 800 mg per day. The moderate and severe groups tolerated 200 mg per day. Pharmacokinetic data in the mild group were similar to the data in the normal group. Comparison of the median Cmax and area under the curve [AUC(0–24)] in the moderate or severe groups at 200 mg per day to the values in the normal and mild groups at 800 mg per day indicated less than dose–proportional systemic exposures in patients with moderate and severe hepatic impairment. This suggests that the lower maximum-tolerated dose in the moderate and severe group is not due to a decrease in drug clearance or alteration in the proportion of metabolites. Conclusions: In patients with mild liver dysfunction, pazopanib is well tolerated at the Food and Drug Administration (FDA)–approved dose of 800 mg per day. Patients with moderate and severe liver dysfunction tolerated 200 mg per day. Clin Cancer Res; 19(13); 3631–9. ©2013 AACR.

Mechanisms of cross-resistance to methotrexate and 5-fluorouracil in an A2780 human ovarian carcinoma cell subline resistant to cisplatin☆

Some properties of the human ovarian carcinoma line A2780 and a subline three times more resistant than the parent line to cisplatin are compared in this report. The rates of uptake and release of cisplatin were similar in the two cell lines. Resistance to cisplatin was associated with: (a) cross-resistance to 5-fluorouracil and methotrexate; (b) a 2.5-fold increase in thymidylate synthase, as measured by both enzyme activity and the capacity to complex 5-fluorodeoxyuridylate; and (c) an increase in the intracellular pools of 5,10-methylenetetrahydrofolate and tetrahydrofolate. These data suggest that cross-resistance to 5-fluorouracil and methotrexate in A2780 cells may be a consequence of increases in their respective target enzymes.

Mechanisms for Cisplatin-FUra Synergism and Cisplatin Resistance in Human Ovarian Carcinoma Cells both in vitro and in vivo

Cisplatin and FUra act synergisticly in human carcinomas. An increase in the availability of reduced folates necessary for tight binding of FdUMP to thymidylate synthase (TS) contributes to the enhanced cytotoxicity of this drug combination. The human ovarian A2780 cell line made three-fold resistant to cisplatin has been shown to have a three-fold elevation of m-RNA for dihydrofolate reductase (DHFR) and TS. However, this increase did not result from an amplification of the genes for these two enzymes. In contrast, ovarian carcinoma cells from patients who failed treatment with cisplatin and FUra have been shown to have both enhanced gene expression and increased gene copy number for DHFR and TS.