631 The Time to Therapeutic Serum Levels of Vancomycin in Orthopaedic Patients

Introduction

Vancomycin is a commonly used antibiotic in the treatment of deep-seated infections. However, the current dosing calculator utilized in NHS Lothian may not adequately achieve therapeutic vancomycin serum concentrations (VSC), of 15-20mg/L, in a timely manner. We aimed to reaudit the length of time for vancomycin to reach therapeutic levels in orthopaedic patients using the new Lothian calculator. A previous audit loop looked at the current calculator in 2018.

Method

Inclusion criteria orthopaedic patients who were treated with vancomycin at the Royal Infirmary Edinburgh, data collection to finish mid-September. The duration to reach the therapeutic SVC, initial trough SVC and serial levels were recorded. A life-table analysis will be used to examine the data.

Results

First audit had Twenty-three patients. The mean initial trough VSC was 12.7mg/L. The mean duration to therapeutic VSC was 5.2 (± 1.3) days. Statistics not completed for second cycle, but initial data shows improvement in time to VSC.

Conclusions

A delay in reaching therapeutic concentrations was observed in a significant proportion of patients using the current calculator. A more rapid achievement of therapeutic levels is required to maximize the period of antibiotic delivery and subsequently improve patient outcomes. The new calculator pilot will hopefully show that improvement.

Combined analysis of two phase II trials of imatinib in advanced dermatofibrosarcoma protuberans (DFSP)

10520

Background: DFSP is an infiltrative, low-grade, dermal tumor with propensity to recur locally and occasionally metastasize. Translocation between COL1A1 on chromosome 17 and PDGFB on chromosome 22, which results in transcriptional upregulation of PDGFB, is characteristic of DFSP. Autocrine/paracrine PDGFB-mediated activation of PDGFRB drives DFSP proliferation. Two distinct phase II trials of imatinib in patients (pts) with locally advanced or metastatic DFSP were conducted, 1 in North America (SWOG) with confirmed objective response rate and 1 in Europe (EORTC) with 14 week progression-free rate as primary end-points. Methods: Pts with locally advanced or metastatic DFSP were eligible. In the EORTC trial confirmation of t(17;22) by FISH was prospectively required for participation, imatinib was started at 400mg bid, surgery was undertaken after 14 weeks if feasible and response was assessed at 14 weeks. Full accrual was to be 44 pts in one step. In the SWOG trial confirmation of t(17;22) by RT-PCR was performed after enrollment, imatinib was started at 400mg daily and response was assessed every 8 weeks. Full accrual was to be 40 pts in 2 steps. Results: 16 pts were enrolled in EORTC and 8 pts enrolled in SWOG trial. The studies were closed early because of slow accrual and regulatory approval of imatinib in DFSP. Pts age ranged from 24 to 70 yrs, DFSP was located on head/neck, trunk and extremity in 7, 11 and 6 pts, respectively, ranged in size from 1.2–49 cm and was classic, pigmented and fibrosarcomatous DFSP in 13, 1 and 7 pts, respectively. One patient did not have DFSP on central review, lacked t(17;22) and thus was ineligible. Metastases were present in 7 pts involving lung in 6 pts. 11 pts (46%) had partial response, 9 pts had stable disease and 4 pts had progressive disease as best response. Median time to progression was 1.7 yrs. Response and progression-free at 1 yr rates were similar between studies. Imatinib was stopped in 11 pts for progression, 1 pt for toxicity, 2 pts resected free of gross disease and 1 pt withdrew. Conclusions: Imatinib is active in DFSP harboring t(17;22) with an objective response rate approaching 50% and is active in fibrosarcomatous DFSP. Response rates and time to progression did not appear to differ between pts taking 400 mg daily versus 400 mg bid.

[Table: see text]

Phase II study of hydroxyurea for unresectable meningioma (Southwest Oncology Group S9811)

2063

Background: Meningiomas account for 15%-18% of CNS tumors. Although benign, recurrence is seen in 16%-39% of cases, depending on the extent of resection possible. Tumor location may make further resection hazardous. Chronic hydroxyurea (HU) was reported to produce well documented objective responses in a small series of patients, with gradual regression occurring over 6–10 months. Induction of apoptosis was furthermore demonstrated with HU in primary benign meningioma explant cultures. The S9811 phase II trial was undertaken to estimate the objective response rate, if any, of unresectable benign meningioma to this HU regimen. Methods: Eligibility required unresectable, measurable, residual or recurrent, histologically-proven benign meningioma. Progressive tumor or progressive neurologic deficit was required. No prior cytotoxics, no radiation therapy for >1 year. Age > 18, adequate hematologic reserve, PS 0–2. HU 20 mg/kg/day po was given for up to 2 years if there was no progressive disease. Single-stage accrual of 38 pts would have allowed detection of 5% null hypothesis response probability vs. 20% with 90% power; the 28 pts actually accrued provide 81% power. Results: Between November 98 and June 2005, 29 pts were accrued, with study closure due to slow accrual. 1 ineligible. Response assessment showed CR+PR 0% (95% CI 0–12%); SD 71% (95% CI 51–87%); PD 21% (95% CI 8–41%); undetermined 7%. Median PFS was 27 months. (95% CI 12–29 months.); 3-year PFS 43% (95% CI 25–61%). Median OS has not been reached. Seven patients were removed from study for toxicity (5/7 hematological). Toxicity was mainly hematologic: 11/28 (39%) grade 3, 2/28 (11%) grade 4. Grade 3 non-hematologic toxicity was seen in 7/28 (25%). Conclusions: Chronic HU therapy for unresectable benign meningioma resulted in an estimated objective response rate of < 12%. Whether the stable disease rate seen differs in any way from what can be expected from the natural history of meningioma cannot be determined from this phase II study design.

No significant financial relationships to disclose.

SWOG 0514: A phase II study of sorafenib (BAY 43–9006) as single agent in patients (pts) with unresectable or metastatic gallbladder cancer or cholangiocarcinomas

4639

Background: There are no standard chemotherapeutic regimens for incurable biliary adenocarcinomas. Gemcitabine and fluoropyrimidine- based chemotherapy results in occasional responses and a median survival approaching 6 months. Given the presence of b- raf mutations and overexpression of VEGF in biliary cancers, we initiated a study to evaluate the efficacy of sorafenib, a multitargeted tyrosine kinase inhibitor of c and b-Raf, VEGFR-2/3 and PDGFR, in pts with metastatic biliary cancers. Methods: Pt eligibility included adequate organ function and no prior treatment for metastatic disease. The primary end-point was objective response rate (RR). Secondary endpoints were overall survival (OS) and progression free survival (PFS). A two-stage design was used to detect a difference in the null hypothesis of 5% response probability and the alternative 20% response probability. If at least one confirmed response occurred after the first 25 pts, another 25 were to be accrued. Sorafenib was administered at 400 mg PO BID continuously. A cycle was defined as 28 days of therapy, and radiological assessment was done every 2 cycles. Results: 36 pts were enrolled during the first stage of accrual. 5 pts were ineligible. 52% were female. Median age was 57.8 years (range 33.8–81.5). Adverse events: 1 pt died with grade 4 supraventricular tachycardia and venous thromboembolism. Grade 3/4 toxicities were noted in 20 pts (66.7%) and included hand-foot syndrome in 4 pts (13%), while thrombosis/embolism, elevated liver transaminases, and abdominal pain were each seen in 3 pts (10% for each). Reversible posterior leukoencephalopathy syndrome, GI perforation, and GI hemorrhage were each seen in 1 pt (3% for each). 2 pts (6%) had an unconfirmed partial response and 9 pts (29%) had stable disease. 27 pts have progressed. Median PFS was 2 months (95% CI: 2–4 months). 14 pts have died, with a median survival estimate of 6 months (95% CI: 4–10 months). Conclusions: Sorafenib did not result in a clinically significant objective RR in pts with gallbladder and cholangiocarcinoma but demonstrated an impact on survival that may be comparable to commonly used chemotherapy regimens.

No significant financial relationships to disclose.

Comparison of two doses of imatinib for the treatment of unresectable or metastatic gastrointestinal stromal tumors (GIST): A meta-analyis based on 1,640 patients (pts)

10004

Background: The MetaGIST project aims to further explore the data of the two randomized studies comparing two doses of imatinib (400 mg od vs bid) for the treatment of GIST: EORTC/ISG/AGITG 62005 (EU-AUS) and SWOG/CALGB/NCI-C/ECOG/ICAS S0033 (US-CDN). Methods: End-points were progression free (PFS) and overall survival (OS). Investigated cofactors included age, sex, performance status (PS), primary tumor site, time from diagnosis, prior therapies, baseline biology, and KIT / PDGFRa mutations for a subset of 772 pts (47%). The logrank test (stratified) and the Cox multivariate model with interaction terms were used for the analysis. Results: The median follow-up was 45 months. A small but significant PFS advantage was documented for the high dose arm, consistently in both studies. OS was identical in the two arms (see table ). Males and pts with a poor PS, GIST from bowel origin, baseline low hemoglobin and high neutrophils counts (ANC) had a significant worse PFS (multivariate analysis); these factors are consistent between studies. In pts analyzed for mutations, wild type pts (HR=1.56), KIT exon 9 mutants (HR=2.17) and pts with other mutations (HR=2.56) had a worse prognosis than KIT exon 11 mutants (univariate analysis); all 3 factors remained in the multivariate model. The US-CDN study included significantly (P<0.01) more females, more GIST from bowel or stomach origin, less KIT exon 9 mutants and pts with a lower baseline ANC. In KIT exon 9 mutants, the PFS advantage with high dose imatinib previously reported in the EU- AUS study was not confirmed in the US-CDN dataset, but remains significant in the pooled dataset. The interaction between dose effect on PFS and prognostic factors was siginficant for KIT exon 9 mutations but not for other factors. Conclusions: This analysis confirms a small PFS advantage of high dose imatinib, essentially amongst KIT exon 9 mutants, but no OS advantage. Heterogeneity between the two studies is being further explored.

[Table: see text]

[Table: see text]

Phase II study of erlotinib in metastatic or unresectable malignant peripheral nerve sheath tumors (MPNST)

9518

Background: MPNSTs are rare soft tissue tumors (STS) that are relatively resistant to chemotherapy. 26% have epidermal growth factor receptor (EGFR) amplification. In preclinical studies, NF1/p53 murine MPNSTs in vitro are stimulated by EGF and inhibited by EGFR inhibitors. We proposed to assess response rate (RR) to erlotinib in adult patients with unresectable or metastatic MPNST. Methods: Patients (pts) were required to have measurable disease, Zubrod performance status (PS) <3, adequate organ function, no prior EGFR therapy, and centrally reviewed confirmation of diagnosis. Treatment was erlotinib 150 mg by mouth daily, in continuous 28 day cycles. Disease evaluation was performed every 2 cycles. Results: 24 pts enrolled in 22 months, from 13 institutions. 20 pts were deemed eligible. Median age was 45.3 years; 50% had neurofibromatosis. At enrollment, 15 had a PS of 0–1, 18 had metastatic disease, and 19 had unresectable disease. Pts were heavily pretreated: 9 pts had ≥ 2 prior regimens, 6 pts had 1 prior regimen, and 4 pts had no prior chemotherapy (1 unknown). 19 of 20 pts were assessable for toxicity: 6 pts had grade 3 toxicities; only 1 was hematologic (anemia). Mild rash (in 15 pts) and fatigue (in 8 pts) were the most common side effects. 20 pts were evaluable for response: 1 had stable disease after first evaluation and 19 had no response. Median progression-free survival was 2 months. 14 patients have died; median overall survival was 4 months. Because no objective responses were observed in the first stage of the study, it was closed to further accrual. Conclusions: We were able to accrue pts with a rare STS to a phase II histology specific study through a single adult cooperative group. In spite of preclinical promise of EGFR inhibition, erlotinib does not appear to be active in MPNSTs. To further understand the role of EGFR in MPNST, we are assessing EGFR expression immunohistochemically and performing quantitative PCR for genes altered by EGFR stimulation/inhibition on pt tumors.

No significant financial relationships to disclose.

Evaluation of quantitative real time PCR for the measurement of Helicobacter pylori at low concentrations in drinking water

A rapid DNA extraction and quantitative, real time polymerase chain reaction (QRTPCR) analysis method targeting the ureA gene of Helicobacter pylori was evaluated for the measurement of these organisms on membrane filters at levels that might be expected to be found in drinking water samples. No interference was seen from high levels of background organisms and related, non-target species were detected at approximately 4-5 log(10) lower levels of sensitivity than H. pylori by this assay. A standard curve was generated for the method from analyses of filters containing known numbers of added H. pylori cells. Cell numbers on these filters were determined by staining with a species-specific fluorescent antibody and solid phase cytometry analyses. The mean detection sensitivity of the method was 10 H. pylori cells per filter with a 95% confidence sensitivity of 40 cells and a 95% confidence precision interval of +/-0.57 log(10) based on duplicate analyses of the samples. One liter drinking water samples from several locations in the US were inoculated with the same H. pylori cell suspensions used to generate the standard curve and gave measurements that were consistent with the standard curve suggesting that these sample matrices produced no interference in the method. This method may be useful for the rapid screening of drinking water for H. pylori.

Bicarbonate secretion plays a role in chloride and water absorption of the European flounder intestine

Experiments performed on isolated intestinal segments from the marine teleost fish, the European flounder (Platichthys flesus), revealed that the intestinal epithelium is capable of secondary active HCO3(-) secretion in the order of 0.2-0.3 micromol x cm(-2) x h(-1) against apparent electrochemical gradient. The HCO3(-) secretion occurs via anion exchange, is dependent on mucosal Cl(-), results in very high mucosal HCO3(-) concentrations, and contributes significantly to Cl(-) and fluid absorption. This present study was conducted under in vivo-like conditions, with mucosal saline resembling intestinal fluids in vivo. These conditions result in a transepithelial potential of -16.2 mV (serosal side negative), which is very different from the -2.2 mV observed under symmetrical conditions. Under these conditions, we found a significant part of the HCO3(-) secretion is fueled by endogenous epithelial CO2 hydration mediated by carbonic anhydrase because acetazolamide (10(-4) M) was found to inhibit HCO3(-) secretion and removal of serosal CO(2) was found not to influence HCO3(-) secretion. Reversal of the epithelial electrochemical gradient for Cl(-) (removal of serosal Cl(-)) and elevation of serosal HCO3(-) resulted in enhanced HCO3(-) secretion and enhanced Cl(-) and fluid absorption. Cl(-) absorption via an anion exchange system appears to partly drive fluid absorption across the intestine in the absence of net Na(+) absorption.

A Phase II study of paclitaxel in patients with recurrent malignant glioma using different doses depending upon the concomitant use of anticonvulsants: a North American Brain Tumor Consortium report

BACKGROUND

The primary objective of the current study was to determine the response rate of paclitaxel in patients with recurrent malignant glioma by using different doses dependent on the concomitant use of anticonvulsants. Secondary objectives were to determine the time period to treatment failure, to evaluate toxicities, and to obtain pharmacokinetic data.

METHODS

Adult patients who had recurrent malignant glioma were treated with paclitaxel. Patients were treated at different doses depending on the concomitant use of anticonvulsants known to induce the p450 hepatic enzyme system. Patients on such agents were treated at a dose of 330 mg/m2, whereas those not on these anticonvulsants were treated at a dose of 210 mg/m2. Tumor response was assessed at 6-week intervals. Treatment was continued until documented tumor progression or unacceptable toxicity occurred, or a total of 12 paclitaxel infusions was completed.

RESULTS

From January 1997 to June 1997, 23 patients were treated with paclitaxel. Four patients were ineligible for the current study. Of the 19 eligible patients, there were no responses seen. Four (21%) had stabilization of disease. Median time to treatment failure was 1 month (95% confidence interval [CI], 1-2 mos) and median survival was 7 months (95% CI, 6-10 mos). Three patients were removed from the current study because they had toxicity. Pharmacokinetic studies demonstrated that drug levels and clearance values were consistent with previously reported findings.

CONCLUSION

Even though higher doses were administered to patients who had recurrent malignant glioma and who were on concomitant anticonvulsants, there were no objective responses to paclitaxel. Time to tumor progression was 1 month. Further testing of paclitaxel at this dose schedule does not appear to be warranted in this patient population.

A Phase II study of paclitaxel in patients with recurrent malignant glioma using different doses depending upon the concomitant use of anticonvulsants: a North American Brain Tumor Consortium report

BACKGROUND

The primary objective of the current study was to determine the response rate of paclitaxel in patients with recurrent malignant glioma by using different doses dependent on the concomitant use of anticonvulsants. Secondary objectives were to determine the time period to treatment failure, to evaluate toxicities, and to obtain pharmacokinetic data.

METHODS

Adult patients who had recurrent malignant glioma were treated with paclitaxel. Patients were treated at different doses depending on the concomitant use of anticonvulsants known to induce the p450 hepatic enzyme system. Patients on such agents were treated at a dose of 330 mg/m2, whereas those not on these anticonvulsants were treated at a dose of 210 mg/m2. Tumor response was assessed at 6-week intervals. Treatment was continued until documented tumor progression or unacceptable toxicity occurred, or a total of 12 paclitaxel infusions was completed.

RESULTS

From January 1997 to June 1997, 23 patients were treated with paclitaxel. Four patients were ineligible for the current study. Of the 19 eligible patients, there were no responses seen. Four (21%) had stabilization of disease. Median time to treatment failure was 1 month (95% confidence interval [CI], 1-2 mos) and median survival was 7 months (95% CI, 6-10 mos). Three patients were removed from the current study because they had toxicity. Pharmacokinetic studies demonstrated that drug levels and clearance values were consistent with previously reported findings.

CONCLUSION

Even though higher doses were administered to patients who had recurrent malignant glioma and who were on concomitant anticonvulsants, there were no objective responses to paclitaxel. Time to tumor progression was 1 month. Further testing of paclitaxel at this dose schedule does not appear to be warranted in this patient population.

A phase I study of induction chemotherapy for older patients with newly diagnosed acute myeloid leukemia (AML) using mitoxantrone, etoposide, and the MDR modulator PSC 833: a southwest oncology group study 9617

Older patients with acute myelogenous leukemia (AML) have overexpression of P-glycoprotein (Pgp+), and this has been shown to correlate quantitatively with therapeutic outcome. Since Pgp-mediated efflux of cytotoxic drugs can be inhibited by the cyclosporine analogue, PSC 833, we investigated the use of this agent with a 5-day mitoxantrone/etoposide regimen in patients over age 55 with newly diagnosed AML. Previous studies suggested a 33% incidence of grade IV/V non-hematologic toxicity with the use of mitoxantrone 10 mg/M(2) and etoposide 100 mg/M(2), each for 5 days, in this patient population. Since PSC 833 alters the pharmacokinetic excretion of MDR-related cytotoxins, this phase I dose-finding study was performed to identify doses of mitoxantrone/etoposide associated with a similar 33% incidence of grade IV/V non-hematologic toxicity, when given with PSC 833. Mitoxantrone/etoposide (M/E) doses were escalated in fixed ratio from a starting dose of M: 4 mg/M(2) and E: 40 mg/M(2), to M: 7 mg/M(2) and E: 70 mg/M(2), in successive cohorts of eight patients each. PSC 833 was well tolerated and the MTD of this M/E regimen with PSC 833 in this population was M: 6 mg/M(2) and E: 60 mg/M(2). The complete response (CR) rate for all patients was 50% (15/30) and was considerably higher for de novo than for secondary AML. These data suggest that the addition of PSC 833 to an M/E regimen for older patients with untreated AML is well tolerated but requires a reduction in M/E dosing to avoid increased toxicity.

Cell cycle regulatory gene abnormalities are important determinants of leukemogenesis and disease biology in adult acute lymphoblastic leukemia

To test the hypothesis that cell cycle regulatory gene abnormalities are determinants of clinical outcome in adult acute lymphoblastic leukemia (ALL), we screened lymphoblasts from patients on a Southwest Oncology Group protocol for abnormalities of the genes, retinoblastoma (Rb), p53, p15(INK4B), and p16(INK4A). Aberrant expression occurred in 33 (85%) patients in the following frequencies: Rb, 51%; p16(INK4A), 41%; p53, 26%. Thirteen patients (33%) had abnormalities in 2 or more genes. Outcomes were compared in patients with 0 to 1 abnormality versus patients with multiple abnormalities. The 2 groups did not differ in a large number of clinical and laboratory characteristics. The CR rates for patients with 0 to 1 and multiple abnormalities were similar (69% and 54%, respectively). Patients with 0 to 1 abnormality had a median survival time of 25 months (n = 26; 95% CI, 13-46 months) versus 8 months (n = 13; 95% CI, 4-12 months) for those with multiple abnormalities (P <.01). Stem cells (CD34+lin-) were isolated from adult ALL bone marrows and tested for p16(INK4A) expression by immunocytochemistry. In 3 of 5 patients lymphoblasts and sorted stem cells lacked p16(INK4A) expression. In 2 other patients only 50% of sorted stem cells expressed p16(INK4A). By contrast, p16 expression was present in the CD34+ lin- compartment in 95% (median) of 9 patients whose lymphoblasts expressed p16(INK4A). Therefore, cell cycle regulatory gene abnormalities are frequently present in adult ALL lymphoblasts, and they may be important determinants of disease outcome. The presence of these abnormalities in the stem compartment suggests that they contribute to leukemogenesis. Eradication of the stem cell subset harboring these abnormalities may be important to achieve cure.

A phase II study of high dose ARA-C and mitoxantrone for treatment of relapsed or refractory adult acute lymphoblastic leukemia

PURPOSE

The Southwest Oncology Group performed a Phase II study to investigate the effectiveness of an induction regimen of high dose cytosine arabinoside (ara-C) with high dose mitoxantrone for treatment of relapsed or refractory adult acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

Patients at least 16-years-old with ALL that was in relapse after, or was refractory to, standard induction therapy including at least vincristine and prednisone were eligible, as long as they had no prior treatment with high dose ara-C. The induction regimen included high dose ara-C (3 g/m2 by 3-h i.v. days 1-5) and mitoxantrone (80 mg/m2 by 15-30 min i.v. 12-20 h after the first dose of ara-C). The study design called for a maximum of 55 patients, with early termination if less than nine of the first 30 achieved complete remission.

RESULTS

Thirty-three patients entered the study, and 31 were included in the analysis. All 31 completed one course of induction therapy. Four patients died of infection and a fifth of cardiomyopathy with possible sepsis. Seven patients achieved complete remission (23%; 95% confidence interval 10-41%). One of the seven received syngeneic bone marrow transplantation while in remission, and the other six all relapsed within 10 months. All 31 patients died within 25 months after entering the study.

CONCLUSIONS

The regimen of high dose ara-C and mitoxantrone was found to be insufficiently effective to warrant further investigation.

Phase II study of phenylacetate in patients with recurrent malignant glioma: a North American Brain Tumor Consortium report

PURPOSE

To determine the response rate, time to treatment failure, and toxicity of phenylacetate in patients with recurrent malignant glioma and to identify plasma concentrations achieved during repeated continuous infusion of this agent.

PATIENTS AND METHODS

Adult patients with recurrent malignant glioma were treated with phenylacetate. The schedule consisted of a 2-week continuous, intravenous infusion followed by a 2-week rest period (14 days on, 14 days off). A starting dose of 400 mg/kg total body weight per day of phenylacetate was initially used and subsequently changed to 400 mg/kg/d based on ideal body weight. Intrapatient dose escalations were allowed to a maximum of 450 mg/kg ideal body weight/d. Tumor response was assessed every 8 weeks. The National Cancer Institute common toxicity criteria were used to assess toxicity. Plasma concentrations achieved during the patients' first two 14-day infusions were assessed.

RESULTS

Forty-three patients were enrolled between December 1994 and December 1996. Of these, 40 patients were assessable for toxicity and response to therapy. Reversible symptoms of fatigue and somnolence were the primary toxicities, with only mild hematologic toxicity. Thirty (75%) of the 40 patients failed treatment within 2 months, seven (17.5%) had stable disease, and three (7.5%) had a response defined as more than 50% reduction in the tumor. Median time to treatment failure was 2 months. Thirty-five patients have died, with a median survival of 8 months. Pharmacokinetic data for this dose schedule showed no difference in the mean plasma concentrations of phenylacetate between weeks 1 and 2 or between weeks 5 and 6.

CONCLUSION

Phenylacetate has little activity at this dose schedule in patients with recurrent malignant glioma. Further studies with this drug would necessitate an evaluation of a different dose schedule.

Trisomy 6 as a primary karyotypic aberration in hematologic disorders

We identified seven patients with hematologic disorders and trisomy 6 as the sole karyotypic aberration in bone marrow aspirates or unstimulated peripheral blood. Five patients were male and two were female; all were adults with ages ranging from 22 to 74 years. Three of the seven patients presented with manifestations of peripheral cytopenia. Their bone marrows were hypocellular with slight or no dysplastic changes and without an increase in blasts. One of these patients subsequently developed acute myeloid leukemia (AML-M1). The four remaining patients were initially diagnosed with AML--three consistent with French-American-British classification of M1 and M4 in the fourth patient. These results suggest that trisomy 6 is a nonrandom primary numerical anomaly of myeloid disorders. The association of cytopenia and hypoplastic bone marrow with trisomy 6 may constitute a new, distinctive variant among myelodysplastic syndromes.

Phase I study of paclitaxel in patients with recurrent malignant glioma: a North American Brain Tumor Consortium report

PURPOSE

To determine the maximum-tolerated dose (MTD) of paclitaxel administered as a 3-hour infusion in patients with recurrent malignant glioma.

PATIENTS AND METHODS

Patients were stratified by starting dose of paclitaxel and concurrent anticonvulsant (AC) use and were treated in cohorts of three patients. The starting dose was 240 mg/m2 administered intravenously with escalations of 30 mg/m2 until the MTD was established. Pharmacokinetic data were obtained for each patient for the first infusion. Tumor response was assessed at 6-week intervals and treatment was continued until documented tumor progression, unacceptable toxicity, or a total of 12 paclitaxel infusions.

RESULTS

From April 1995 to December 1996, 34 patients were treated; 27 patients in the AC group and seven patients in the non-AC group. The MTD for patients who received ACs was established at 360 mg/m2 and the dose-limiting toxicity (DLT) was central neurotoxicity, characterized as transient encephalopathy and seizures. In contrast, the MTD for patients who did not receive ACs was 240 mg/m2, and myelosuppression, gastrointestinal toxicity, and fatigue were the DLTs. Pharmacokinetic data confirmed that the plasma drug levels and clearance rates were similar for patients in both groups at the respective dose levels that produced DLTs.

CONCLUSION

The pharmacokinetics of paclitaxel are altered by ACs, and significantly larger doses of the drug can be administered to patients with brain tumors on AC therapy. The toxicity profile is different for patients on AC therapy treated at these higher doses. A phase II study has been initiated that uses a dose of 330 mg/m2 for patients on AC therapy and 210 mg/m2 for patients not on AC therapy.

Characterization and use of an antibody detecting the CBFbeta-SMMHC fusion protein in inv(16)/t(16;16)-associated acute myeloid leukemias

The inv(16)(p13q22) and t(16;16)(p13;q22) cytogenetic abnormalities occur commonly in acute myeloid leukemia (AML), typically associated with French-American-British (FAB) AML-M4Eo subtype. Reverse transcriptase-polymerase chain reaction (RT-PCR) techniques have been recently developed to detect the presence of several variants of the resultant CBFB-MYH11 fusion gene that encodes a CBFbeta-smooth muscle myosin heavy chain (SMMHC) fusion protein. We have now determined the clinical use of a polyclonal antibody [anti-inv(16) Ab] directed against a junctional epitope of the most common type of CBFbeta-SMMHC fusion protein (type A), which is present in 90% of inv(16)/t(16;16) AML cases. Using flow cytometry, reproducible methods were developed for detection of CBFbeta-SMMHC proteins in permeabilized cells; flow cytometric results were then correlated with cytogenetics and RT-PCR detection methods. In an analysis of 42 leukemia cases with various cytogenetic abnormalities and several normal controls, the anti-inv(16) Ab specifically detected all 23 cases that were cytogenetically positive for inv(16) or t(16;16), including a single AML case that was RT-PCR-negative. In addition to detecting all type A fusions, the anti-inv(16) Ab also unexpectedly identified the type C and type D CBFbeta-SMMHC fusion proteins. Molecular characterization of one RT-PCR-positive and Ab-positive t(16;16) case with a non-type A product showed a novel previously unreported CBFB-MYH11 fusion (CBFB nt 455-MYH11 nt 1893). Flow cytometric results were analyzed using the Kolmogorov-Smirnov statistic D-value and the median value for positive samples was 0.65 (range, 0.35 to 0.77) versus 0.07 (range, -0.21 to 0.18) in the negative group (P < .0001). The overall concordance between cytogenetics and RT-PCR was 97%, whereas the concordance between flow cytometry and cytogenetics was 100%. Thus, using the anti-inv(16) Ab, all cytogenetically positive and RT-PCR-positive AML cases with inv(16) or t(16;16) could be rapidly identified. This study demonstrates the use of this antibody as an investigational tool in inv(16)/t(16;16) AML and suggests that the development of such reagents may have potential clinical diagnostic use.

Tumor suppressor gene alteration in adult acute lymphoblastic leukemia (ALL). Analysis of retinoblastoma (Rb) and p53 gene expression in lymphoblasts of patients with de novo, relapsed, or refractory ALL treated in Southwest Oncology Group studies

To examine the impact of inactivation of tumor suppressor genes on outcome in adult ALL, we compared two groups of patients registered to SWOG treatment protocols for loss of the Rb gene product and p53 overexpression: (1) 89 patients with de novo ALL, and (2) 26 patients with relapsed/refractory ALL. The groups were comparable with respect to age, sex, and race. Cell lysates (> or = 80% blasts) were analyzed by immunoblotting which enabled detection of Rb or p53 proteins in as little as 1 microg of lysate. Loss of Rb expression (pRbneg) was found in 54/85 (64%) de novo and 11/19 (58%) relapsed patients (P = 0.79). Overexpression of p53 (p53abn), indicative of p53 point mutations, was found in 16/75 (21%) de novo and 8/19 (42%) relapsed patients (P = 0.08). Using a nonisotopic RNase cleavage assay, p53 point mutations in exons 5-9 were confirmed in 14/23 (61%) p53abn specimens. For the de novo ALL group, patients with normal Rb protein had higher WBC and higher peripheral blast and lymphocyte counts. Otherwise neither abnormal Rb or p53 expression correlated with any of a large panel of clinical and laboratory variables including FAB class, blast lineage, expression of myeloid antigens or CD34, and presence of the Ph1 chromosome or BCR-ABL. Analyses of treatment outcomes demonstrated no significant impact of Rb or p53 status alone on CR rates, relapse-free or overall survival. An identical percentage (11%) of both de novo and relapsed/refractory patients had concurrent abnormalities of both Rb and p53 expression (pRbneg/p53abn). The survival curve of these patients suggests an increased rate of early death, but the number of patients in this group was small. Summarizing, (1) loss of Rb expression is common in adult ALL; (2) overexpression of p53 may be more frequent in relapsed/refractory than de novo adult ALL; and (3) although Rb or p53 alterations alone are not strong independent predictors of outcome, their concurrent expression may predict a poor response to therapy.

In vivo administration of recombinant interleukin-2 induces granulocyte-macrophage colony formation in a murine system

The in vivo administration of recombinant interleukin-2 (rIL-2) in humans has led to anemia, thrombocytopenia, and eosinophilia. In an attempt to evaluate the effects of the in vivo administration of rIL-2 on murine bone marrow, we administered rIL-2 to C57BL/6 female mice i.p. three times a day at doses ranging from 10,000 to 100,000 U for 10 days; we then harvested blood and bone marrow from these animals every other day and performed the following analyses: White blood cell count, red blood cell count, hemoglobin concentration, histogram analysis of nucleated cell volume, manual differential counts, and in vitro colony-forming assays for granulocytes and monocytes (CFU-GM). The administration of rIL-2 induced an overall increase in the total white blood cell count that was dose-dependent for its appearance and overall number. This increase was secondary to an increase in monocytes and granulocytes but not to a change in lymphocyte number. Myeloid proliferative activity measured by CFU-GM revealed a biphasic pattern of activity. An early proliferation at 2 days was not followed by lymphocytosis. However, a second peak of proliferation at 6 days was associated with peripheral blood granulocytosis and monocytosis. After rIL-2 was discontinued on day 10, the CFU-GM activity returned to normal by days 16-18. These results suggest that the in vivo administration of rIL-2 may play an important role in the regulation of hematopoiesis.

Downstream sequences augment transcription from the essential initiation site of a baculovirus polyhedrin gene

A series of recombinant baculoviruses containing linker-substituted polyhedrin promoters attached to a reporter gene encoding chloramphenicol acetyl transferase (CAT) were constructed and tested for expression of the gene. The major determinant for promoter activity was narrowed to within eight nucleotides, TAAGTATT, at the start point of polyhedrin mRNA transcription. Mutations within TAAGTATT blocked initiation of transcription from this site and resulted in a 2000-fold decrease in CAT activity. Linker mutations from 12 to 22 bases upstream from the TAAGTATT sequence increased the steady-state levels of RNAs initiated within TAAGTATT and increased CAT expression by up to 50%. Mutations downstream from TAAGTATT and within the region specifying the untranslated RNA leader diminished transcriptional initiation at TAAGTATT and decreased CAT activity two- to 20-fold. The half-lives of CAT RNAs were not noticeably affected by mutations in the untranslated RNA leader region and thus RNA turn-over was not responsible for the reduced levels of these CAT RNAs. Nuclear run-on analysis of two mutant viruses showed that these mutations decrease the rate of transcriptional initiation. Transcriptional initiation thus appears to be the major means of polyhedrin gene regulation. The data define promoter-related roles for TAAGTATT and the sequences specifying the untranslated mRNA leader in transcriptional initiation. A model by which the viral-induced RNA polymerase distinguishes late and very late initiation sites is proposed.

Immunological implications and clinical management of prophylactic endodontic treatment

This article discusses a study conducted on patients who underwent prophylactic endodontic treatment. It compares the incidence of flare-ups in allergic and nonallergic patients. The authors further relate this study to one conducted in a previous article.

Eight base pairs encompassing the transcriptional start point are the major determinant for baculovirus polyhedrin gene expression

The effects of mutations within the 92-bp region immediately upstream from the translational initiation ATG of the polyhedrin gene of the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) were determined by plasmid transient expression assays in the presence of wild-type (wt) AcMNPV DNA. Clustered point mutations were generated by substitution of 10-bp stretches of the polyhedrin promoter/leader region with a 10-bp HindIII linker. Three of these linker scan (LS) mutations in the region from nucleotides (nt) -62 to -84 (relative to the original polyhedrin ATG at +1, +2, +3) had no effect or a mild stimulatory effect on reporter gene expression. One mutation immediately upstream (nt -52 to -60) from the transcription start point (at nt -50) reduced expression four-fold. Three overlapping mutations affecting 8 bp from nt -44 to -51 (encompassing the transcriptional start point) reduced expression by 1000-fold. A 1000-fold reduction was also observed for a total deletion of nt -1 and -92. Five LS mutations between nt -1 and -43 each reduced expression two- to five-fold, whereas combining an LS mutation and a 9-bp deletion mutation in the leader reduced expression approx. nine-fold. Reversing the orientation of the reporter gene along with the wt 92-bp upstream polyhedrin promoter/leader sequences resulted in slightly higher expression levels than those observed for the normal orientation indicating that all the essential cis-acting promoter elements, with the possible exception of long-range enhancer sequences, are located downstream from nt -92. Sequences of the AcMNPVhr5 enhancer (homologous region No. 5 of AcMNPV) had only a minor effect on expression from the polyhedrin promoter in transient assays. The results show that 8 bp encompassing the transcriptional start point, a sequence which is conserved in all late AcMNPV promoters, is essential for polyhedrin gene expression. Additional nucleotides within the leader region are necessary for optimal expression.

Nucleotide sequence of a portion of the Autographa californica nuclear polyhedrosis virus genome containing the EcoRI site-rich region (hr5) and an open reading frame just 5' of the p10 gene

The nucleotide sequence of a 1587 bp region lying within the HindIII-Q fragment of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus (AcMNPV) DNA has been determined. It begins in the EcoRI-S-EcoRI-X region, continues to the HindIII-P/Q boundary and contains an open reading frame that codes for a polypeptide of 240 amino acids (p26). This open reading frame is also included in the 1100 and 1500 base transcripts previously mapped to this region. The sequence reveals that the 5' ends of the 1100 and 1500 base transcripts are located 20 bp downstream from the end of a putative TATA box (TAATTAAAT) and 19 bp upstream from the translation start codon (ATG) of the p26 open reading frame. The translation termination codon (TAA) falls in the immediate 5' flanking region of the major late p10 gene of AcMNPV, 3 bp downstream from the putative TATA box. The probable polyadenylation site for the 1100 base transcript lies 23 bp downstream from the cap site for the 750 and 2500 base transcripts encoding the p10 protein. The 5' flanking region of the p26 open reading frame contains the EcoRI site-rich region, hr5, whose sequence is included here. The EcoRI site-rich region, hr5, consists of six imperfect tandem repeats of a sequence that includes the EcoRI recognition site. These direct repeats also include many inverted repeats.

Physical mapping of temporally regulated, overlapping transcripts in the region of the 10K protein gene in Autographa californica nuclear polyhedrosis virus

We investigated transcriptional activity in the region of a gene for a major late protein (10 kilodaltons) of Autographa californica nuclear polyhedrosis virus. This 10K protein gene spans an HindIII cleavage site, with the 5' end of the gene located in the HindIII-Q fragment and the 3' end in the HindIII-P fragment. Northern blot analysis showed that there were at least four transcripts mapping in this region, two that are present maximally at 12 h (1,500 and 1,100 bases in length) and two that are present at 24 h (750 and 2,500 bases in length). Northern blot analysis also suggested that these transcripts overlap. S1 mapping identified the precise positions of the transcripts and confirmed the overlap. The 1,500- and 1,100-base transcripts share a common 5' end, about 1,056 bases upstream from the HindIII-P-Q boundary; the 750- and 2,500-base transcripts share a common 5' end, about 303 bases upstream from the HindIII-P-Q boundary. The 1,100-base transcript terminates in the Q fragment, about 234 bases from the HindIII-P-Q boundary. The other three transcripts all end in the P fragment. Both the 1,500- and the 750-base transcripts terminate approximately 240 bases from the HindIII-P-Q boundary. The 2,500-base transcript exhibits 3'-end heterogeneity, ending around 2,046 bases from the HindIII-P-Q boundary. Therefore, three different transcripts (1,500, 750, and 2,500 bases in length) contain the complete 10K protein coding region. A fourth transcript (1,100 bases in length) overlaps the 750-base 10K protein gene transcript by 70 bases.