Brian P. Monahan

Rituximab Therapy in Hematologic Malignancy Patients With Circulating Blood Tumor Cells: Association With Increased Infusion-Related Side Effects and Rapid Blood Tumor Clearance

PURPOSE Rituximab was recently approved for use in relapsed, low-grade non-Hodgkins lymphoma; however, few data exist regarding the safety of this agent in patients with a high number of tumor cells in the blood. METHODS AND RESULTS After the observation at our institution of a rapid reduction of peripheral-blood tumor cells with associated severe pulmonary infusion-related toxicity in two patients with refractory hematologic malignancies, data on three additional cases were collected from physician-submitted reports of adverse events related to rituximab treatment. Five patients with hematologic malignancies possessing a high number of blood tumor cells were treated with rituximab and developed rapid tumor clearance. The median age was 68 years (range, 26 to 78 years). Patients were diagnosed with B-cell prolymphocytic leukemia (n = 2), chronic lymphocytic leukemia (n = 2), or transformed non-Hodgkins lymphoma (n = 1). All of these patients had bulky adenopathy or organomegaly. All five patients developed a unique syndrome of severe infusion-related reactions, thrombocytopenia, rapid decrement in circulating tumor cell load, and mild electrolyte evidence of tumor lysis, and all required hospitalization. In addition, one patient developed ascites. These events resolved, and four patients were subsequently treated with rituximab without significant complications. CONCLUSION Rituximab administration in patients who have a high number of tumor cells in the blood may have an increased likelihood of severe initial infusion-related reactions. These data also suggest that rituximab may have activity in a variety of other lymphoid neoplasms, such as chronic lymphocytic leukemia and B-cell prolymphocytic leukemia.

Dose-Escalating and Pharmacological Study of Oxaliplatin in Adult Cancer Patients With Impaired Renal Function: A National Cancer Institute Organ Dysfunction Working Group Study

PURPOSE This study was undertaken to determine the toxicities, pharmacokinetics, and maximum tolerated doses of oxaliplatin in patients with renal impairment and to develop formal guidelines for oxaliplatin dosing in this patient population. PATIENTS AND METHODS Thirty-seven adult cancer patients with variable renal function received intravenous oxaliplatin at 60 to 130 mg/m2 every 3 weeks. Patients were stratified by 24-hour creatinine clearance (CrCL) into four cohorts: group A (controls, CrCL > or =60 mL/min), group B (mild dysfunction, CrCL 40 to 59 mL/min), group C (moderate dysfunction, CrCL 20 to 39 mL/min), and group D (severe dysfunction, CrCL <20 mL/min). Doses were escalated in cohorts of three patients, and urine and plasma ultrafiltrates were assayed for platinum concentrations. RESULTS No dose-limiting toxicities were observed in any patient group during the first cycle of therapy. Escalation of oxaliplatin to the maximum dose of 130 mg/m2 was well tolerated in all patient groups with a CrCL > or =20 mL/min (groups A, B, and C). Pharmacokinetic analysis showed that patients with decreased CrCL had a corresponding decrease in the clearance of plasma ultrafiltrable platinum (r2 = 0.765). However, oxaliplatin-induced side effects were not more common or severe in patients with mild to moderate renal dysfunction, despite the decrease in ultrafiltrable platinum clearance. CONCLUSION Oxaliplatin at 130 mg/m2 every 3 weeks is well tolerated by patients with mild to moderate degrees of renal dysfunction. These data strongly support the recommendation that dose reductions of single-agent oxaliplatin are not necessary in patients with a CrCL greater than 20 mL/min.

Sequence-dependent antagonism between fluorouracil and paclitaxel in human breast cancer cells

The effects of 24-hr exposures to 5-fluorouracil (FUra) and paclitaxel in various sequences were studied in MCF-7 breast cancer cells to determine an optimal schedule for possible clinical use. In clonogenic assays, pre-exposure to FUra followed by paclitaxel resulted in marked antagonism, while sequential paclitaxel followed by FUra was optimal. Concurrent or pre-exposure to paclitaxel did not affect [3H]FUra metabolism, [3H]FUra-RNA incorporation, or the extent of FUra-mediated thymidylate synthase inhibition. Paclitaxel led to G2/M phase accumulation that persisted for up to 24 hr after drug exposure, while a 24-hr FUra exposure produced S-phase accumulation. FUra pre-exposure diminished paclitaxel-associated G2/M phase block, whereas subsequent exposure to FUra after paclitaxel did not. FUra exposure resulted in transient induction of p53 and p21, which returned to basal levels 24 hr after drug removal. p53 and p21 protein content also increased markedly during paclitaxel exposure, accompanied by phosphorylation of Bcl-2. Double-stranded DNA fragmentation (approximately 50 kb) was seen at 48 hr when cells were exposed to paclitaxel for an initial 24-hr period. Paclitaxel-associated DNA fragmentation was not prevented by concurrent or subsequent exposure to FUra. Thus, paclitaxel-mediated G2/M phase arrest appeared to be a crucial step in induction of DNA fragmentation. Since an initial 24-hr paclitaxel exposure did not interfere with subsequent FUra metabolism or thymidylate synthase inhibition, and delayed exposure to FUra did not impede either paclitaxel-mediated induction of mitotic blockade or DNA fragmentation, the sequence of paclitaxel followed by FUra is recommended for clinical trials.

Phase I and Pharmacokinetic Trial of Weekly Oral Fluorouracil Given With Eniluracil and Low-Dose Leucovorin to Patients With Solid Tumors

PURPOSE Fluorouracil (5-FU) given as a weekly, high-dose 24-hour infusion is active and tolerable. We evaluated an oral regimen of eniluracil (which inactivates dihydropyrimidine dehydrogenase [DPD]), 5-FU, and leucovorin to simulate this schedule. PATIENTS AND METHODS Patients received a single 24-hour infusion of 5-FU (2,300 mg/m(2) on day 2) with leucovorin (15 mg orally [PO] bid on days 1 through 3) to provide reference pharmacokinetic data. Two weeks later, patients began treatment with eniluracil (20 mg) and leucovorin (15 mg) (PO bid on days 1 through 3) and 5-FU (10 to 15 mg/m(2) PO bid on day 2). RESULTS Dose-limiting toxicity (diarrhea, neutropenia, and fatigue) was seen with 5-FU 15 mg/m(2) PO bid on day 2 given weekly for either 6 of 8 weeks or 3 of 4 weeks, whereas five of seven patients tolerated 5-FU 10 mg/m(2) PO bid given weekly for 3 of 4 weeks. Eniluracil led to a 35-fold reduction in 5-FU clearance. Fluoro-beta-alanine, a 5-FU catabolite, was not detected in plasma during oral 5-FU-eniluracil therapy. DPD activity was markedly suppressed in all patients during eniluracil therapy; the inactivation persisted after the last eniluracil dose; percentages of baseline values were 1.8% on day 5, 4.5% on day 12, and 23.6% on day 19. CONCLUSION The recommended oral dosage of 5-FU (10 mg/m(2) PO bid) given with eniluracil and leucovorin is approximately 115-fold lower than the reference dosage for 24-hour infusional 5-FU. This difference is greater than expected given the reduction in 5-FU clearance. DPD inactivation persisted for several weeks after completion of eniluracil therapy.

A Phase I Pharmacologic and Pharmacogenetic Trial of Sequential 24-Hour Infusion of Irinotecan Followed by Leucovorin and a 48-Hour Infusion of Fluorouracil in Adult Patients with Solid Tumors

Purpose: In preclinical studies, sequential exposure to irinotecan (CPT-11) then fluorouracil (5-FU) is superior to concurrent exposure or the reverse sequence; a 24-hour infusion of CPT-11 may be better tolerated than shorter infusions. Experimental Design: CPT-11 was first given at four levels (70-140 mg/m2/24 hours), followed by leucovorin 500 mg/m2/0.5 hours and 5-FU 2,000 mg/m2/48 hours on days 1 and 15 of a 4-week cycle. 5-FU was then increased in three cohorts up to 3,900 mg/m2/48 hours. Results: Two patients had dose-limiting toxicity during cycle 1 at 140/3,900 of CPT-11/5-FU (2-week delay for neutrophil recovery; grade 3 nausea despite antiemetics); one of six patients at 140/3,120 had dose-limiting toxicity (grade 3 diarrhea, grade 4 neutropenia). Four of 22 patients with colorectal cancer had partial responses, two of which had prior bolus CPT-11/5-FU. The mean 5-FU plasma concentration was 5.1 μmol/L at 3,900 mg/m2/48 hours. The end of infusion CPT-11 plasma concentration averaged 519 nmol/L at 140 mg/m2/24 hours. Patients with UDP-glucuronosyltransferase (UGT1A1; TA)6/6 promoter genotype had a lower ratio of free to glucuronide form of SN-38 than in patients with ≥1 (TA)7 allele. Thymidylate synthase genotypes for the 28-base promoter repeat were 2/2 (13%), 2/3 (74%), 3/3 (13%); all four responders had a 2/3 genotype. Conclusions: Doses (mg/m2) of CPT-11 140/24 hours, leucovorin 500/0.5 hours and 5-FU 3,120/48 hours were well tolerated.

Extraocular muscle palsy from metastatic prostate cancer

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