A Phase 2 Study of PCI-27483, a Factor VIIa Inhibitor in Combination with Gemcitabine for Advanced Pancreatic Cancer

OBJECTIVES

Tissue factor overexpression is associated with tumor progression, venous thromboembolism, and worsened survival in patients with cancer. Tissue factor and activated factor VII (FVIIa) complex may contribute to tumor invasiveness by promoting cell migration and angiogenesis. The study objective was to evaluate safety, pharmacokinetics, and efficacy of PCI-27483, a selective FVIIa inhibitor.

METHODS

This was an open-label, multicenter phase 2 trial of patients with advanced pancreatic cancer. Part A of the study was an intrapatient dose escalation lead-in portion in patients concurrently receiving gemcitabine, and in part B, patients were randomized 1: 1 to the recommended phase 2 dose combination PCI-27483-gemcitabine versus gemcitabine alone.

RESULTS

Target international normalized ratio (between 2.0-3.0) was achieved following PCI-27483 treatment. Overall safety of PCI-27483-gemcitabine (n = 26) was similar to gemcitabine alone (n = 16), with a higher incidence of mostly low-grade bleeding events (65% vs. 19%). Progression-free survival (PFS) and overall survival (OS) were not significantly different between patients treated with PCI-27483-gemcitabine (PFS: 3.7 months, OS: 5.7 months) and those treated with gemcitabine alone (PFS: 1.9 months, OS: 5.6 months).

CONCLUSIONS

Targeted inhibition of the coagulation cascade was achieved by administering PCI-27483. PCI-27483-gemcitabine was well tolerated, but superiority to single agent gemcitabine was not demonstrated.

l-Cysteine and glutathione restore the reduction of rat hippocampal Na+, K+-ATPase activity induced by aspartame metabolites

Studies have implicated aspartame (ASP) ingestion in neurological problems. The aim of this study was to evaluate hippocampal Na(+),K(+)-ATPase and Mg(2+)-ATPase activities after incubation with ASP or each of ASP metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (asp) separately. Suckling rat hippocampal homogenates or pure Na(+),K(+)-ATPase were incubated with ASP metabolites. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were measured spectrophotometrically. Incubation of hippocampal or pure Na(+),K(+)-ATPase with ASP concentrations (expected in the cerebrospinal fluid (CSF)) after ASP consumption of 34, 150 or 200mg/kg resulted in hippocampal enzyme activity reduction of 26%, 50% or 59%, respectively, whereas pure enzyme was remarkably stimulated. Moreover, incubation with hippocampal homogenate of each one of the corresponding in the CSF ASP metabolites related to the intake of common, high/abuse doses of the sweetener, inhibited Na(+),K(+)-ATPase, while pure enzyme was activated. Hippocampal Mg(2+)-ATPase remained unaltered. Addition of l-cysteine (cys) or reduced glutathione (GSH) in ASP mixtures, related with high/toxic doses of the sweetener, completely or partially restored the inactivated membrane Na(+),K(+)-ATPase, whereas the activated pure enzyme activity returned to normal. CSF concentrations of ASP metabolites related to common, abuse/toxic doses of the additive significantly reduced rat hippocampal Na(+),K(+)-ATPase activity, whereas pure enzyme was activated. Cys or GSH completely or partially restored both enzyme activities.

Freehand three-dimensional assessment of left ventricular volumes and ejection fraction with ultrasound contrast agent LK565

AIMS

Accurate assessment of left ventricular function by determining left ventricular volumes and ejection fraction is important in evaluating the prognoses of patients with heart failure. Two-dimensional (2D) echocardiography suffers from low correlation with reference methods like ventriculography. Three-dimensionally (3D) assessed data have been proved to have better conformity. Endocardial border delineation remains a problem, however, especially in patients with suboptimal recordings. Few data exist on 3D-echocardiographic volumetry with ultrasound contrast agents (UCAs). We evaluated the second-generation UCA LK565 for its boundary-tracing capacities in freehand 3D echocardiography in a phase II clinical trial. Safety and efficacy of the novel contrast agent were also evaluated.

METHODS AND RESULTS

Forty patients between the age of 42 and 77 were included in this trial. Left ventricular end-systolic and -diastolic volume (LVESV, LVEDV) and ejection fraction (EF) were determined by either 2D or 3D freehand second harmonic echocardiography with and without use of LK565. Parameters were compared statistically with ventriculography performed in 35 patients. Immune response to LK565 was evaluated by analysing phagocytosis capacity and kinetics of inflammatory cytokines (TNF-alpha, IL-4, IL-10, IFN-gamma). Patients were monitored for adverse events up to 72 h after application of the UCA. Calculated values for left ventricular volumes and ejection fraction correlated best for freehand 3D echocardiography in combination with LK565 (r=0.92 for LVEDV; r=0.96 for LVESV; r=0.94 for EF). Excellent left ventricular contrast enhancement was achieved for approximately 8 min. A reversible saturation of phagocytosis capacity for monocytes and neutrophils set in with a maximum peak at 6h. No significant increase in cytokine expression was observed.

CONCLUSION

LK565 improves feasibility of endocardial border delineation in 3D echocardiography, leading to better correlation of left ventricular volumetry with reference methods. Efficacy and safety of LK565 are equivalent to those of conventional UCAs.

Immunological evaluation of the new stable ultrasound contrast agent LK565: a phase one clinical trial

Background

Ultrasound contrast agents (UCAs) allow the enhancement of vascular definition, thereby providing more diagnostic information. LK565 is a new second-generation UCA based on synthetic polymers of aspartic acid which is eliminated from the blood stream via phagocytosis. LK565 forms very stable air-filled microspheres and is capable of repeated passage through the pulmonary capillary bed after peripheral intravenous injection. This characteristic allows examination of the cardiac function or extracardiac vessel abnormalities up to 15 minutes.

Methods

A phase one clinical study was conducted on 15 healthy volunteers to identify the development of an undesirable immune response. Phagocytosis capacity, TNF-α secretion, and MHC class II upregulation of monocytes was monitored, as well as microsphere specific antibody development (IgM, IgG). Furthermore, the kinetics of the activation surface markers CD69, CD25, CD71, and CD11b on leukocytes were analyzed.

Results

Due to LK565-metabolism the administration of the UCA led to saturation of phagocytes which was reversible after 24 hrs. Compared to positive controls neither significant TNF-α elevation, neither MHC class II and activation surface markers upregulation, nor specific antibody development was detectable.

Conclusion

The administration of LK565 provides a comfortable duration of signal enhancement, esp. in echocardiography, without causing a major activation cascade or triggering an adaptive immune response. To minimize the risk of undesirable adverse events such as anaphylactoid reactions, immunological studies should be included in clinical trials for new UCAs. The use of LK565 as another new ultrasound contrast agent should be encouraged as a safe means to provide additional diagnostic information.

Glutamate transporters and retinal excitotoxicity

Glutamate appears to play a major role in several degenerative retinal disorders. However, exogenous glutamate is only weakly toxic to the retina when glutamate transporters on Müller glial cells are operational. In an ex vivo rat retinal preparation, we previously found that exogenous glutamate causes Müller cell swelling but does not trigger excitotoxic neurodegeneration unless very high concentrations that overwhelm the capacity of glutamate transporters are administered. To determine the role of glutamate transporters in Müller cell swelling and glutamate-mediated retinal degeneration, we examined the effects of DL-threo-beta-benzyloxyaspartate (TBOA), an agent that blocks glutamate transport but that unlike most available transport inhibitors is neither a substrate for transport nor a glutamate receptor agonist. We found that TBOA triggered severe retinal neurodegeneration attenuated by ionotropic glutamate receptor antagonists. TBOA-induced neuronal damage was also diminished by riluzole, an agent that inhibits endogenous glutamate release. In the presence of riluzole, to inhibit glutamate release plus TBOA to block glutamate uptake, the addition of low concentrations of exogenous glutamate triggered severe excitotoxic neuronal damage without inducing Müller cell swelling. We conclude that TBOA-sensitive glutamate transporters play an important role in regulating the neurodegenerative effects of glutamate in the rat retina.

[Therapy of cardiac arrhythmias. Clinical significance of potassium- and magnesium aspartate in arrhythmias]

Potassium and magnesium deficiencies usually coexist and represent a risk factor for cardiac arrhythmias. Serum levels--in particular of magnesium--are inconclusive for establishing a possible electrolyte deficiency. Basic treatment of arrhythmia should therefore include the administration of potassium and magnesium, since the benefit is great, and the possible side effects is negligible. A placebo-controlled study involving patients with cardiac arrhythmias revealed that appreciably fewer ventricular asystoles occurred after three weeks of treatment with potassium and magnesium aspartate, even when serum levels were within the normal range prior to initiating treatment. Patients older than 50, and those with previous coronary heart disease and/or myocardial infarction derived particular benefit from this form of treatment.

CONCLUSION

These results underscore the key role played by potassium and magnesium in the treatment of cardiac arrhythmias.

Epileptic seizures induced by N-acetyl-L-aspartate in rats: in vivo and in vitro studies

Tremor rat (tm/tm), the parent strain of spontaneously epileptic rat (SER: zi/zi, tm/tm), exhibits absence-like seizures characterized by 5-7 Hz spike-wave-like complexes on cortical and hippocampal electroencephalograms (EEG) after 10 weeks of age, prior to development of convulsive seizures. Recently, this animal model has been demonstrated to display a genomic microdeletion within the critical region of tm, where aspartoacylase hydrolyzing N-acetyl-L aspartate (NAA) is located, besides showing the ability to accumulate NAA in the brain. Therefore, the present study was performed to determine the involvement of NAA in the induction of epileptic seizures. When NAA (4 micromol) was applied intracerebroventricularly (i.c.v.) to normal Wistar rats, 4-10 Hz polyspikes and/or spike-wave-like complexes followed by absence-like seizure before persistent 1-5 Hz waxing high-voltage after-discharges were observed on cortical and hippocampal EEG. At a higher dose (8 micromol), NAA induced convulsive seizures. The absence-like seizures with polyspikes and/or spike-wave-like complexes on the EEG were also observed with i.c.v. NAA in premature tremor rats without seizures. The NAA-induced seizures in normal rats were antagonized by i.c.v. glutamic acid diethyl ester, a non-selective glutamate receptor antagonist. In addition, NAA applied to the bath rapidly induced a long-lasting depolarization concomitantly with repetitive firings in hippocampal CA3 neurons of normal rat brain slice preparations. These findings suggest that NAA is involved in the induction of absence-like seizures and/or convulsion, probably via glutamate receptors.

PALA versus streptozotocin, doxorubicin, and MeCCNU in the treatment of patients with advanced pancreatic carcinoma

Seventy-three eligible, chemotherapy-naive, ambulatory patients with advanced pancreatic carcinoma were allocated to one of two treatment regimens: 35 received PALA (1250 mg/m2 daily x 5 every 4 weeks) and 38 were given SAM (streptozotocin 400 mg/m2 i.v. daily x 5, doxorubicin 45 mg/m2 i.v. on day 1 and 22, and methyl CCNU 60 mg/m2 orally on days 1 and 22 every 6 weeks). Doses were modified for myelo-, gi-, or cardiotoxicity. Adequate organ, bone marrow and cardiac function; a measurable lesion; adequate caloric intake; and a life expectancy of 2 months were required for treatment on this trial. One patient on each regimen had a partial response for response rates of 3% (95% confidence intervals, 0.08 to 17%). Median survival on the PALA arm was 5 months and median time to treatment failure was 2.6 months. SAM patients experienced median overall and progression free survivals of 3.4 and 1.9 months, respectively. The severe toxicity observed was almost exclusively myelosuppression on both regimens. One patient receiving SAM had lethal leukopenic sepsis during the first cycle as the only treatment-related death. Neither PALA nor SAM offer any therapeutic utility to patients with advanced pancreatic cancer.

Effects of PALA on the pharmacokinetics of 5-fluorouracil

N-(phosphonacetyl)-L-aspartate (PALA) modulates the activity of 5-fluorouracil (5-FU) by inhibiting pyrimidine biosynthesis. A cross-over study was conducted to determine whether PALA affects the pharmacokinetic parameters of 5-FU in patients given 5-FU/folinic acid (FA). Six patients (3 males, 3 females) aged 63 4.3 (mean SD) years (body surface area of 1.84 18 m2) with metastatic colorectal carcinoma were given two courses of treatment. The treatment consisted of 250 mg/m2 of PALA on day 1 followed by 20 mg/m2 FA and 400 mg/m2 5-FU (5 min i.v. bolus injection) on days 2-5 in one cycle of treatment (PALA+). In another treatment cycle, these doses of 5-FU and FA were given for all 5 days without PALA (PALA-). The two courses were given four weeks apart. It was determined by random selection whether the course with PALA was given before or after the course without PALA. Blood samples were collected over a period of three hours, starting from the beginning of 5-FU infusion on days 2 and 5 of both courses. Plasma concentrations of 5-FU were determined by an HPLC technique. Pharmacokinetic parameters were calculated using a non-compartmental model. While there were no significant differences between pharmacokinetic parameters in the PALA+ vs PALA- courses, there was a trend towards a decreasing area under the curve (AUC) and increasing clearance (Cl) in PALA+ courses of treatment.

Modulation of 5-fluorouracil with methotrexate and low-dose N-(phosphonacetyl)-L-aspartate in patients with advanced colorectal cancer. Results of a phase II study

Methotrexate (MTX) and N-phosphonacetyl-L-aspartate acid (PALA) have been shown to modulate the cytotoxic effects of 5-fluorouracil (5-FU). A phase II study was initiated to evaluate the feasibility, toxicity and efficacy of PALA/MTX and 5-FU in patients with metastatic colorectal cancer. 26 patients received PALA 250 mg/m2 as an intravenous 15-min infusion plus MTX 200 mg/m2 as a 30-min intravenous (i.v.) infusion on day 1 and 5-FU 600 mg/m2 as i.v. push on day 2. Cycles were repeated every 14 days and the 5-FU dose was escalated in the individual patient in steps of 100 mg/m2 for the third, fifth and seventh cycle in the absence of toxicity. 7 patients had received prior 5-FU-based chemotherapy while 19 patients were chemotherapy naive. Objective responses occurred in 23% of patients (1 CR, 5 PR of which 2 were pretreated), no change in 13 patients (50%) and tumour progression (6 patients) or toxic death (one patient) in 27%. Responses lasted for a median of 7 months (range 6-9), the median time to progression was 4 months and median survival 13 months. Toxicity was mainly gastrointestinal with diarrhoea and mucositis, and severe or life threatening in only 3 patients. In 3 patients an increase in serum glucose levels occurred while being treated with PALA/MTX and 5-FU. 2 patients with insulin-dependent diabetes had a 33% increase in insulin requirement and 1 patient with dietary-controlled diabetes died due to a ketoacidotic coma. PALA/MTX/5-FU in this dose and schedule is active in patients with colorectal cancer. Hyperglycaemia may be a potential side-effect of PALA-containing regimens especially in patients with diabetes. Careful monitoring of serum glucose levels in these patients is indicated.

Magnesium in the prophylaxis of migraine--a double-blind placebo-controlled study

The migraine prophylactic effect of 10 mmol magnesium twice-daily has been evaluated in a multicentre, prospective, randomized, double-blind, placebo-controlled study. Patients with two to six migraine attacks per month without aura, and history of migraine of at least 2 years, were included. A 4-week baseline period without medication was followed by 12 weeks of treatment with magnesium or placebo. The primary efficacy end-point was a reduction of at least 50% in intensity or duration of migraine attacks in hours at the end of the 12 weeks of treatment compared to baseline. With a calculated total sample size of 150 patients, an interim analysis was planned after completing treatment of at least 60 patients, which in fact was performed with 69 patients (64F, 5M), aged 18-64 years. Of these, 35 had received magnesium and 34 placebo. The number of responders was 10 in each group (28.6% under magnesium and 29.4% under placebo). As determined in the study protocol, this was a major reason to discontinue the trial. With regard to the number of migraine days or migraine attacks there was no benefit with magnesium compared to placebo. There were no centre-specific differences, and the final assessments of treatment efficacy by the doctor and patient were largely equivocal. With respect to tolerability and safety, 45.7% of patients in the magnesium group reported primarily mild adverse events like soft stool and diarrhoea in contrast to 23.5% in the placebo group.

Phase I study of N-(phosphonacetyl)-L-aspartate with fluorouracil and with or without dipyridamole in patients with advanced cancer

We conducted a combined biochemical modulation trial of N-(phosphonacetyl)-L-aspartate (PALA), dipyridamole (DP), and fluorouracil (5-FU) in patients with cancer. Eighty-eight patients with advanced cancer were entered into this Phase I trial. During the first part of the study, four doses of PALA (125, 250, 500, and 1000 mg/m2, administered on day 1) were evaluated to determine the PALA dose with maximal suppression of aspartate transcarbamylase (ATCase) activity that was clinically tolerable. Patients were randomized to receive DP (or no DP), 50 mg/m2, p.o. every 6 h on days 1-6, and all patients received 5-FU, 400 mg/m2, by bolus administration on days 2-5. Prior to and during therapy, WBCs were collected and assayed for ATCase activity. After the maximally tolerated PALA dose with 400 mg/m2 5-FU +/- 50 mg/m2 DP was defined, the 5-FU dose was escalated using the same administration schedule of 5-FU, PALA, and DP. The dose of 5-FU was escalated by 25% in each of the DP cohorts until dose-limiting toxicity was reached. ATCase activity was inhibited in a dose-dependent manner with PALA doses of 125, 250, 500, and 1000 mg/m2, resulting in 0, 13, 17, and 49% inhibition of ATCase activity. Only at the higher PALA doses (i.e., 500 and 1000 mg/m2) was ATCase activity suppressed during days 2-5, but the activity returned to pretreatment levels by day 15. Based on the clinical tolerance and significant suppression of ATCase activity, a PALA dose of 500 mg/m2 was selected for the 5-FU dose escalation phase. At a 5-FU dose of 625 mg/m2, dose-limiting toxicity (leukopenia, stomatitis, and diarrhea) occurred in both DP cohorts. We recommend that for this monthly treatment schedule, 500 mg/m2 PALA and 500 mg/m2 5-FU, with or without 50 mg/m2 DP, be used in subsequent Phase II trials.

Therapeutic availability of iron administered orally as the ferrous gluconate together with magnesium-L-aspartate hydrochloride

Since in vitro experiments had excluded interactions between Fe-gluconate (Fe-gluc) and magnesium-L-aspartate hydrochloride (MAH) in aqueous solutions the present in vivo studies seemed to be justified. Animal studies: Rats were kept on magnesium-(Mg)- and iron-(Fe)- sufficient and deficient diets. The intragastral administration of Fe-gluc significantly increased plasma Fe after 3 h, either given alone, or in combination with MAH (inducing hypermagnesemia). Same results were obtained when fortified diets were offered to Fe/Mg-deficient animals. Human studies: The combination of Fe-gluc (2 x 50 mg Fe per day, per os) plus MAH (2 x 7.5 mmol Mg per day, p.o.) was well tolerated by healthy volunteers. Single dose experiments revealed that Fe-gluc alone and in combination with MAH increased plasma Fe levels during 3 h to the same extent. Two groups of pregnant women with moderately reduced hemoglobin levels either received Fe-gluc (out-patients) or its combination with MAH (at least temporarily hospitalised because of preterm labor). Treatments were well tolerated. Hemoglobin levels did not further decrease, as expected without Fe supplements, during the course of pregnancy, thus indicating the therapeutic availability of the electrolytes in both study groups. Progesterone-induced constipation is frequently observed during pregnancy; hence stool softening reported by 50% of the women receiving Fe-gluc plus MAH (versus 33% in the Fe-gluc group) can be regarded as desirable effect. It is concluded that MAH does not interfere with the enteral absorption of Fe-gluc when both electrolytes are orally administered together. Taking both electrolytes together instead of 2 to 3 h apart from each other, as actually recommended, means a less complicated dosage regimen and probably improves compliance.

Phase II trial of low-dose N-(phosphonacetyl)-disodium L-aspartic acid and high-dose 24-hour infusional 5-fluorouracil in advanced gastric adenocarcinoma. A Southwest Oncology Group study

N-(phosphonacetyl)-disodium L-aspartic acid (PALA) demonstrates a synergistic antitumor effect when combined with 5-Fluorouracil (5-FU) in in vitro studies. In a Phase II trial, 23 eligible patients with unresectable or metastatic adenocarcinoma of the stomach were treated with weekly i.v. bolus PALA (250 mg/M2) followed 24 hours later by a 24-hour infusion of 5-FU (2600 mg/M2) for an initial period of 8 weeks. No objective responses were noted. PALA and 5-FU is inactive against gastric adenocarcinoma at the doses and schedule used in this trial.

Phase I trial of low dose N-phosphonacetyl-L-aspartic acid and high dose 5-fluorouracil administered concomitantly with radiation therapy for unresectable localized adenocarcinoma of the pancreas

BACKGROUND

Preclinical and clinical data suggest that N-phosphonacetyl-L-aspartic acid (PALA) can augment the cytotoxic effects of 5-fluorouracil (5-FU). In addition, the combination of 5-FU and radiation therapy has been used with success in prolonging survival and providing palliation of symptoms in patients with advanced unresectable pancreatic carcinoma. This Phase I study was undertaken to determine the feasibility and evaluate the qualitative and quantitative toxicities of PALA and escalating doses of 5-FU administered concomitantly with radiation therapy in patients with locally advanced nonmetastatic pancreatic adenocarcinoma.

METHODS

Ten previously untreated patients with advanced nonmetastatic adenocarcinoma of the pancreas were treated with 250 mg/m2 of PALA given as an intravenous bolus followed 24 hours later by 5-FU, which was given by continuous 24-hour infusion every week. The 5-FU doses were assigned according to a Phase I drug escalation (1000 mg/m2, 1300 mg/m2, and 1700 mg/m2). Radiation therapy was delivered concurrently with chemotherapy at a dose of 180 cGy per fraction (900 cGy per week) over 6 1/2 weeks. PALA and 5-FU were continued weekly after the end of radiation therapy, with disease assessments made every 8 weeks. Chemotherapy was continued until the disease progressed.

RESULTS

All 10 patients were evaluable. The maximum tolerated dose (MTD) of 5-FU was 1300 mg/m2. Two of the four patients treated at the 1700 mg/m2 dose level experienced dose-limiting toxicities, nausea/vomiting and mucositis, respectively. Toxicities were mild to moderate at the 1000 mg/m2 and 1300 mg/m2 dose levels. Two patients treated with 5-FU at the 1300 mg/m2 dose level had complete responses, and one patient treated at the 1700 mg/m2 dose level had a partial response. The median survival was 12.5 months, and four patients survived more than 1 year.

CONCLUSIONS

PALA and 5-FU administered concomitantly with radiation therapy is an active regimen in locally advanced, unresectable pancreatic cancer. Dose-limiting toxicities are nausea/vomiting and mucositis. The MTD of 5-FU is 1300 mg/m2. The regimen is well tolerated and administered in an outpatient setting.

Reduction of blood pressure with oral magnesium supplementation in women with mild to moderate hypertension

In a double-blind controlled trial, 91 middle-aged and elderly women with mild to moderate hypertension who were not on antihypertensive medication were randomly assigned to treatment with magnesium aspartate-HCl (20 mmol Mg/d) or placebo for 6 mo. Magnesium aspartate-HCl in the given dose was well-tolerated and was not associated with an increased frequency of diarrhea compared with placebo. At the end of the study, systolic blood pressure had fallen by 2.7 mm Hg (95% CI -1.2, 6.7; P = 0.18) and diastolic blood pressure by 3.4 mm Hg (1.3, 5.6; P = 0.003) more in the magnesium group than in the placebo group. Blood pressure response was not associated with baseline magnesium status, as measured by dietary magnesium intake and urinary magnesium excretion. Urinary magnesium excretion in the magnesium group increased by 50% during the intervention period. No changes were seen in other biochemical indexes, including serum concentrations of total and high-density-lipoprotein cholesterol. The findings suggest that oral supplementation with magnesium aspartate-HCl may lower blood pressure in subjects with mild to moderate hypertension.

A phase I-II study of N-(phosphonacetyl)-L-aspartic acid (PALA) added to 5-fluorouracil and folinic acid in advanced colorectal cancer

N-(phosphonacetyl)-L-aspartic acid (PALA) inhibits the enzyme L-aspartic acid transcarbamoylase (ATCase) which is important in de novo pyrimidine synthesis. Low dosages of PALA modulate the in vitro activity of 5-fluorouracil (5-FU) and PALA (250 mg/m2) inhibits pyrimidine synthesis in patients. PALA (250 mg/m2 day 1) was combined with an established 5-FU/folinic acid (FA) regimen [FA (200 mg/m2 over 2 h days 2 + 3) and bolus and 22 h infusional 5-FU (300-500 mg/m2 days 2 + 3)] without the need for dose reduction of 5-FU or FA. 35 patients were entered. Treatment was well tolerated; 4/27 patients experienced > or = ECOG grade 3 toxicity at full 5-FU dosage (500 mg/m2 bolus/infusion). However, the response rate in 33 evaluable patients was only 6.1% [95% confidence intervals (C.I.) 0.2-21.8%]. Median response duration was short (4 months, 95% C.I. 3-6 months) and overall median survival was 10 months (95% C.I. 7-16 months). Although PALA (250 mg/m2) can be combined with full dosage 5-FU/FA, the combination has poor activity in colorectal cancer.

Phase I study of high dose 5-fluorouracil and high dose Leucovorin with low dose phosphonacetyl-L-aspartic acid in patients with advanced malignancies

Twenty-eight patients with refractory advanced malignancies were treated with a 24 hr infusion of 5-fluorouracil (5-FU), Leucovorin (LV), and N-(phosphonacetyl)-L-aspartic acid (PALA) weekly. Twenty-seven patients were evaluable for the assessment of toxicity and anti-tumor activity. PALA was administered as intravenous bolus over 15 min at a fixed dose, 250 mg/m2 24 hr before the start of 5-FU and LV infusions. 5-FU was initially administered at 750 mg/m2 and was incrementally increased to 2600 mg/m2. LV was administered in a fixed dose of 500 mg/m2 concurrently with 5-FU over a 24-hr period. The course was repeated weekly. Diarrhea, stomatitis, nausea, and vomiting were among dose-limiting toxic effects. Other toxicities observed were hand-foot syndrome, hair loss of scalp/eyelashes, overall weakness, rhinitis, and chemical conjunctivitis. Maximum tolerated dose (MTD) of 5-FU in this combination and schedule was 2600 mg/m2. Seven of 14 patients treated at 2600 mg/m2 were able to tolerate the chemotherapy on a weekly basis without interruption. The other seven patients required dose de-escalation, a majority of whom contained 5-FU at a dose of 2100 mg/m2. Twenty-three of 27 patients had been previously treated. Eight patients achieved a partial response, all of whom were previously treated, except three patients. A complete response was observed in a patient with pancreatic carcinoma, previously untreated. Overall response rate for the patients who were treated at the 5-FU dose of 2100 mg/m2 or 2600 mg/m2 is 9 of 18 patients (50%).

Phase II trial of PALA in combination with 5-fluorouracil in advanced pancreatic cancer

Phosphonacetyl-L-aspartate (PALA), in inhibitor of aspartate transcarbamylase that depletes uridine nucleotide pools, selectively potentiates the antitumor activity of 5-fluorouracil (5-FU) in preclinical models. Due to the promising results we obtained using PALA/5-FU in colorectal cancer, we performed a phase II trial in patients presenting with advanced pancreatic cancer. PALA was given intravenously at 250 mg/m2 on day 1, followed 24 h later by 2,600 mg/m2 5-FU given by 24-h infusion. Treatments were repeated weekly. A total of 41 patients who had not previously undergone chemotherapy were entered in the trial; of these, 35 were evaluable for response. Toxicity was generally mild to moderate; neurotoxicity (13/35) and diarrhea (8/35) predominated. Among the 35 patients, 1 achieved a complete response and 4, a partial remission, for an overall response rate of 14%. The median survival was 5.1 months. Pretreatment with PALA alone was not sufficient to enhance the activity of 5-FU in pancreatic cancer.

[Lithium in the treatment of chronic alcoholic patients with brain damage--a controlled study]

The efficacy of lithium aspartate in reducing alcohol consumption was examined in a double-blind, placebo controlled cross-over study. Subjects were male alcohol-dependent in-patients with organic brain disorder of moderate or severe degree. Starting with 22 men who fulfilled our selection criteria, only 8 finished the seven months trial (one month base-line, three months placebo, three months lithium). Measures of treatment response were the number of drinking episodes and the severity of intoxication on each episode (both registered by the nursing staff). Both measures showed no evidence of different responses to lithium and placebo treatment.

A phase II trial of PALA + dipyridamole in patients with advanced soft-tissue sarcoma

A total of 21 patients with advanced soft tissue sarcoma enrolled in a phase II trial of 3.5 g/m2 N-phosphonacetyl-L-aspartate (PALA) given intravenously every 3 weeks plus 50 mg/m2 dipyridamole (Persantine) given orally every 6 h. Dipyridamole administration was initiated 1 week before the first dose of PALA. Peak and trough plasma concentrations of dipyridamole were measured before and after the first dose of PALA in 14 patients. In all, 19 patients were evaluable for therapeutic response. One subject experienced partial regression of a pulmonary metastasis; no other major response was observed. Diarrhea was the most prominent toxicity; in one patient it was life-threatening and was associated with a severe rash. On the day preceding PALA administration, the median peak plasma concentration of dipyridamole was 2,208 ng/ml and the median trough value was 904 ng/ml. Similar values were obtained on the day of PALA administration. Although the levels achieved were similar to those required to modulate the activity of PALA in preclinical systems, the therapeutic results obtained in the present study were not superior to those reported for PALA alone in previously treated patients with soft-tissue sarcoma.

Phase II study of biochemical modulation of fluorouracil by low-dose PALA in patients with colorectal cancer

Higher response rates in colorectal cancer have been observed with regimens that increase the cytotoxicity of fluorouracil (5-FU) by altering the biochemical milieu at its site(s) of action. Phosphonacetyl-L-aspartate (PALA), which inhibits aspartate transcarbamylase and depletes uridine nucleotide pools in vitro and in vivo, selectively potentiates the antitumor activity of 5-FU in preclinical models. In a phase I/II study in patients with advanced colorectal cancer, PALA 250 mg/m2 was given on day 1, followed 24 hours later by 5-FU 2,600 mg/m2 by 24-hour infusion repeated weekly. Through the use of subcutaneous ports and portable infusion pumps, all patients were treated outside the hospital setting. Thirty-nine patients without prior chemotherapy received 884 courses of treatment. The primary site was colon in 31, rectum in eight. Toxicity was generally mild to moderate except among four patients who were escalated to 5-FU 3,250 mg/m2: two developed severe gastrointestinal toxicity and myelosuppression. Among the remaining 35 patients, gastrointestinal and neurologic toxicities predominated, but usually did not develop until the third or fourth month of treatment. Two patients were inevaluable for response. Among the 37 evaluable patients there were three complete and 13 partial remissions for a total response rate of 43% (95% confidence interval [Cl], 27% to 59%). The median duration of response was 5 months (range, 1.5 to 15 months). The projected mean survival is in excess of 17 months. This high response rate is comparable to the best results obtained with other means of modulation of 5-FU. Demonstration of a survival benefit will require larger phase III studies.

A clinical trial of biochemical modulation of 5-fluorouracil with N-phosphonoacetyl-L-aspartate and thymidine in advanced gastric and anaplastic colorectal cancer

A novel sequential administration schedule of PALA (N-phosphonoacetyl-L-aspartate) and thymidine to enhance the cytotoxic effect of 5-fluorouracil (5FU) was tested in 36 patients with advanced gastric cancer and 21 patients with advanced poorly differentiated (anaplastic) colorectal cancer. The potency of 5FU was dramatically increased as indicated by the observation of dose-limiting leukopenia at less than one tenth the maximum tolerated dose of 5FU when given as a single agent by intravenous bolus technique. Twenty-five percent of gastric cancer patients and 33% of colorectal cancer patients experienced an objective tumor response, including three patients with complete response. However, response duration was brief (median, 6 months), and there were four treatment-related fatalities due to severe and unpredictable leukopenia leading to sepsis. Survival was short with a median of 6 months for gastric cancer patients and 3 1/2 months for colorectal cancer patients. We conclude that therapeutic index of 5FU was not improved by the addition of PALA and thymidine in this patient population based on considerations of objective tumor response rate, patient survival, and toxicity.

Reversible microproteinuria induced by L-aspartate infusion

Infusion of an acidic amino acid, L-aspartate, to 10 volunteers resulted in transient, significant increases in urinary excretion of the major urinary trypsin inhibitor (p less than 0.002) and beta 2-microglobulin (p less than 0.02). Simultaneously with the proteinuria, urinary pH rose significantly (p less than 0.02). These changes appeared following the infusion and after the excretion of L-aspartate had reached the preinfusion level. Albumin excretion was unchanged indicating that the proteinuria was due to a decreased tubular reabsorption. The mechanism for the reversible tubular proteinuria is unknown. A simple pH effect due to alkalization of the urine was excluded, as NaHCO3 infusion was not followed by an increase in the excretion of the major urinary trypsin inhibitor and beta 2-microglobulin.

A pilot study of magnesium aspartate hydrochloride (Magnesiocard) as a mood stabilizer for rapid cycling bipolar affective disorder patients

1. Nine severe rapid cycling manic-depressive patients were treated with a magnesium preparation, Magnesiocard 40 mEq/day in an open label study for a period up to 32 weeks. 2. Magnesiocard was found to have clinical results at least equivalent to those of lithium in about 50% of these patients. These results were obtained in an exploratory study and should be interpreted with caution. 3. The possibility that Magnesiocard could replace or improve the efficacy of lithium as a preventive treatment of manic-depressive illness merits further clinical investigation.

A randomized phase I and II study of short-term infusion of high-dose fluorouracil with or without N-(phosphonacetyl)-L-aspartic acid in patients with advanced pancreatic and colorectal cancers

Fifty-two patients with advanced gastrointestinal (GI) malignancies who had not received previous chemotherapy or radiation therapy were randomized to be treated either with 24-hour infusion of weekly fluorouracil (5-FU) or the same plus N-(phosphonacetyl)-L-aspartic acid (PALA). Forty-seven patients were evaluable for the assessment of toxicity and antitumor activity. PALA was administered as an intravenous (IV) bolus over 15 minutes at a fixed dose, 250 mg/m2. The latter agent was administered 24 hours before the start of 5-FU infusion. 5-FU was initially administered at 750 mg/m2 and was incrementally increased to 3,400 mg/m2. In both arms of the randomized study, the courses were repeated every week. In both arms of the study, ataxia and myelosuppression were the dose-limiting toxic effects. At 5-FU dose of 3,400 mg/m2, one patient in each arm developed grade 3 hematologic toxicity. Other reversible side effects included grade 2 skin changes, nausea, and vomiting. During the administration of 2,600 mg/m2 of 5-FU over 24 hours, the steady state plasma 5-FU concentration was approximately 20 mumol/L. The maximum tolerated dose (MTD) for 5-FU for protracted treatment is 2,600 mg/m2 in either arm of the study. Therapeutic response was predominantly seen in the combination arm: there were two patients with complete response (CR) and 11 patients with partial response (PR) of 28 patients in the study. In the 5-FU alone arm there were four PR and 19 patients in the study.

Phase I trial of combination therapy of cancer with N-phosphonacetyl-L-aspartic acid and dipyridamole

While N-phosphonacetyl-L-aspartic acid (PALA), an inhibitor of de novo pyrimidine biosynthesis, demonstrated a unique spectrum of activity during preclinical drug evaluation, multiple clinical trials have shown it to possess minimal clinical activity. One explanation for the disappointing results is the possibility that tumor cells are able to utilize circulating uridine in the synthesis of pyrimidines (salvage pathway). Dipyridamole, an inhibitor of nucleoside transport, has been demonstrated experimentally to potentiate the cytotoxicity of PALA significantly. In addition, this agent has a long safety record when used clinically in man. A phase I trial of this two-drug combination was therefore conducted, with a fixed oral dose of dipyridamole (50 mg/m2 every 6 h) and an escalating i.v. dose of PALA administered every 3 weeks. The dose-limiting toxicity with this schedule was diarrhea and abdominal cramping pain at a PALA dose of 3900-4200 mg/m2. Among the 65 patients participating in this trial 4 objective responses (2 partial, 2 minimal) were observed. Because of the potential for unique clinical synergy between PALA and dipyridamole further investigation should be considered.

A controlled evaluation of recent approaches to biochemical modulation or enhancement of 5-fluorouracil therapy in colorectal carcinoma

Three hundred thirty-five previously untreated patients with advanced colorectal carcinoma were randomly assigned to treatment with 5-fluorouracil (5-FU) alone, 5-FU plus N-(phosphonacetyl)-L-aspartic acid (PALA), 5-FU plus high-dose thymidine, 5-FU plus levamisole, or 5-FU plus methyl CCNU, vincristine, and streptozotocin (MOF-Strept). Dosages were designed to produce definite toxicity in the majority of patients, although the nature of dose-limiting reactions varied considerably among regimens. 5-FU alone and 5-FU plus levamisole produced mucocutaneous reactions, diarrhea, and leukopenia; 5-FU plus PALA produced primarily mucocutaneous reactions and diarrhea; 5-FU plus thymidine produced leukopenia with occasional neurotoxicity and hypotension; and MOF-Strept produced substantial nausea and vomiting with both thrombocytopenia and leukopenia. Objective response rates among patients with measurable disease varied from 12% (5-FU plus PALA) to 34% (MOF-Strept), but none of the regimens were significantly superior to 5-FU alone. Both interval to progression and survival were comparable among the five regimens with no reasonable chance that any combination regimen could produce as much as a 50% improvement when compared with 5-FU alone. Whereas we observed definite modulation of 5-FU dose--toxicity relationships, particularly with the thymidine and PALA combinations, this did not result in a detectable improvement in therapeutic effect. None of the combination regimens, administered in the dosages and schedules we used, can be recommended as standard therapy of advanced colorectal carcinoma.

Clinical trial of sequential N-phosphonacetyl-L-aspartate, thymidine, and 5-fluorouracil in advanced colorectal carcinoma

Preclinical studies have demonstrated enhanced cytotoxic effects of 5-fluorouracil (5-FU) when given in conjunction with N-phosphonacetyl-L-aspartate (PALA) or thymidine in several murine systems. Early clinical studies have demonstrated significant delayed depletion of pyrimidine nucleotides in tumor biopsy specimens following systemic PALA administration and prolonged serum levels of 5-FU after thymidine administration. Each of these biochemical effects would be anticipated to augment the cytotoxic activity of 5-FU. A phase II trial of a timed sequential administration schedule of PALA, thymidine, and 5-FU was conducted in 37 patients with advanced measurable colorectal cancer. Ten of 37 patients (27%) experienced objective tumor responses with a median response duration of 22 weeks, and 18 patients (49%) had stable disease for a median duration of 20 weeks. Six of 13 patients (46%) with anaplastic histology and/or rapidly progressive tumors experienced high-quality tumor responses. Leukopenia and neurologic side effects were the primary toxicities, including one death caused by sepsis. This regimen has demonstrated striking alteration in the 5-FU dose-effect relationship and definite antitumor activity in patients with advanced colorectal cancer. Further trials in patients with anaplastic carcinomas of the colon or other anatomic sites should be considered.

Phase II study of PALA, amsacrine, teniposide, and zinostatin in small cell lung carcinoma (EST 2579)

Eighty-two patients with small cell lung carcinoma refractory to standard chemotherapy were entered in this phase II randomized study of PALA, amsacrine, teniposide, and zinostatin. Of the 66 evaluable patients, one partial response occurred among 17 patients treated with teniposide and no responses occurred with the other drugs. Two patients each treated with amsacrine and teniposide experienced life-threatening hematologic toxic effects and one patient treated with zinostatin died of thrombocytopenic pulmonary hemorrhage. The overall median patient survival was 9.6 weeks. Weight loss greater than or equal to 5% prior to therapy, extensive disease, and a nonambulatory status were associated with poor survival.

Phase II evaluation of PALA in patients with refractory metastatic sarcomas

The efficacy of PALA was evaluated in 22 patients with metastatic soft tissue and bone sarcomas. The 20 evaluable patients had received a median of three prior chemotherapeutic regimens, including an adriamycin combination, to which eight had shown response. PALA was administered at 2-week intervals. Sixteen patients received 6 g/m2 over 1 hour intravenously as their initial dose, while six patients received 5 g/m2. The major side effects were skin rash, stomatitis, diarrhea, nausea, and vomiting. Significant myelosuppression was not seen. Two patients had stabilization of disease for periods of 10 and 13 weeks. At the dose and schedule used in this trial, PALA was not effective against advanced adult sarcoma.

A phase II study of PALA (NSC 224131) in patients with advanced ovarian carcinoma. A Gynecologic Oncology Group study

Pala, 5G /M2 i.v. every 3 weeks was given to 32 evaluable patients with ovarian carcinoma (31 previously treated). No complete or partial responses were noted. Ten patients had stable disease for a median progression-free interval of 4.7+ months, while the remainder had progression of disease from the start of therapy. The major toxicity was dermatologic, and five patients had severe skin rash with desquamation or ulceration. There was no substantial hematologic or gastrointestinal toxicity. PALA displays no useful activity in previously-treated patients with ovarian cancer.

PALA, vindesine, and cisplatin combination chemotherapy in advanced malignant melanoma. A pilot study

Twenty-two patients with advanced malignant melanoma were entered in a pilot study receiving combination chemotherapy with PALA, vindesine, and cisplatin (PVP). Treatment consisted of PALA 3000 mg/m2 IV on days 1 and 2, vindesine 3 mg/m2 IV on days 1 and 8, cisplatin 30 mg/m2 IV on days 1 through 5, with treatment cycles repeated on day 21 every 3 weeks. Of 22 patients, 3 had non-visceral disease confined to iuxtaregional tumor growth (Stage III), and 19 had disseminated and/or visceral disease (Stage IV). The male/female sex distribution was 13/9; median age was 45 years. All 22 patients had measurable disease; 21 were evaluable for response and toxicity. Five patients (24%) had a complete response (CR) with a median duration of 5 months, and four patients (19%) had a partial response (PR) with a median duration of 3 months. Seven patients showed disease stabilization (33%) with a median duration of 2 months. Progressive disease was seen in five patients (24%) and was commonly due to widespread visceral disease. CR could be found predominantly in non-visceral disease, whereas PR could be observed in visceral disease also. Survival time from the onset of PVP chemotherapy cannot be estimated finally, since some of the responses are continuing at the present time, and 7 of 21 patients are still alive. Currently, median survival time for responders is 8 months, and for nonresponders, 5 months. Toxicity of PVP chemotherapy is mild to moderate and allows cytotoxic drug administration on an outpatient basis. PVP chemotherapy appears to have significant activity against malignant melanoma and may therefore be an alternative regimen in the management of advanced disease. However, despite the relative high remission rate especially in non-visceral disease, response duration remains disappointingly low.

Phase II trial of PALA in lymphoma: an Eastern Cooperative Oncology Group study

A phase II trial of PALA in malignant lymphoma was carried out by the Eastern Cooperative Oncology Group. The occurrence of hematologic toxicity in 17 of 35 patients in the study was noteworthy and was possibly related to prior therapy and/or marrow involvement. The finding of thromboembolic phenomena in four of five autopsied patients was also noteworthy. No antitumor activity was recorded. This experience discourages further trials of PALA in patients with malignant lymphoma.

Treatment of psoriasis with N-phosphonacetyl-L-aspartate

Seven patients with severe psoriasis were treated with the aspartate carbamylase inhibitor N-phosphonacetyl-L-aspartate (PALA). Three patients showed a definite improvement lasting up to 3 months after each course of therapy. Three other patients showed more limited responses of shorter duration, and one patient experienced progressive worsening of his psoriasis while on the study. Psoriatic arthritis did not appear to be improved by the PALA therapy. Side effects were usually mild and limited to skin irritation and diarrhea. The development of alternate schedules of administration may lead to a more useful treatment response in patients with severe psoriasis.

A Phase I study of the combination N-(phosphonacetyl)-L-aspartate (PALA, NSC-224131) and L-alanosine (NSC-153353) in patients with advanced cancer

This article reports a Phase I study of combined therapy with N-(phosphonacetyl)-L-aspartate (PALA) and L-alanosine in 26 patients with advanced cancer. Each agent exhibits antitumor effect by enzyme inhibition: PALA blocks pyrimidine biosynthesis by impeding aspartate transcarbamylase and L-alanosine depletes purine nucleotides by interfering with adenylosuccinate synthetase. These agents were selected for clinical investigation in light of synergistic cytotoxicity in vitro against human tumor cell lines and in vivo against P-388 murine leukemia resistant to cytosine arabinoside. Dose-limiting toxicities were stomatitis and diarrhea to a lesser extent. There was no substantial myelosuppression. The authors recommend either of two intravenous regimens for studies of therapeutic activity in selected patients with neoplastic diseases: a one-day treatment repeated of PALA, 5.0 g/m2 and L-alanosine, 3.0 g/m2, repeated every 3 weeks; or a monthly program of PALA, 500 mg/m2/d 1-5 and L-alanosine, 60 mg/m2/d 1-5.

Phase I and clinical pharmacological evaluation of biochemical modulation of 5-fluorouracil with N-(phosphonacetyl)-L-aspartic acid

5-Fluorouracil (FUra) is a clinically useful antineoplastic agent. Preclinical studies suggest that the therapeutic effects of FUra can be enhanced by pretreatment with N-(phosphonacetyl)-L-aspartic acid (PALA), an inhibitor of aspartate transcarbamylase. The objective of treatment with PALA is to increase the activation of FUra by inhibiting the normal pathway of de novo pyrimidine biosynthesis. Theoretically, the optimal dose of PALA should produce effective blockade of this pathway without increasing toxic effects of FUra. Using pyrazofurin-induced orotic aciduria and orotidinuria as a measure of this pathway, it as determined that PALA (250 mg/sq m) is effective in inhibiting total-body pyrimidine synthesis. Sixty-eight adult patients with cancer were treated with combinations of PALA and FUra. High doses of PALA (1 to 2 g/sq m) prevented the use of full dosage of FUra; however, PALA (250 mg/sq m) can be administered 24 hr before FUra (750 mg/sq m) once weekly for at least 3 weeks. The toxicity observed using that combination of doses was mild to moderate myelosuppression, mucositis, diarrhea, nausea, and vomiting. Further clinical studies are warranted.

Continuous five-day infusion of PALA and 5FU: a pilot phase II trial

In order to determine whether a simultaneous infusion of N-(phospho-n-acetyl)-L-aspartic acid (PALA) was able to increase the rate of antitumor response to 5-fluorouracil (5-FU), a pilot study was conducted. Of 10 evaluable patients with previously drug-untreated colorectal carcinoma, there were only two partial responses, lasting 2.3 and 1.6 months. No partial responses were observed in three evaluable patients with soft tissue sarcomas. The dose-limiting toxicity was dermatitis. The simultaneous infusion of PALA and 5-FU is not likely to produce a high number of antitumor responses of long duration in patients with colorectal carcinoma.

PALA in advanced breast cancer. A phase II pilot study by the ECOG

Thirty-three patients with advanced breast cancer were treated with PALA at a schedule of 1500 mg/m2/day for 5 days every 3 weeks. Time to progression varied from 4-305 days from the start of therapy (median, 49 days) with 3 partial responses (9%) for 231, 180, and 64 days, respectively. Toxicity was considerable, with severe skin and mucosal toxicity occurring in 48% and 39% of cases, respectively. Hematologic toxicity was usually mild. We conclude PALA has limited activity in advanced breast cancer, but may be of advantage in combination chemotherapy because of the relative bone marrow-sparing properties.

N-(phosphonacetyl)-L-aspartate (PALA) in advanced malignant melanoma: a phase II trial of the EORTC Malignant Melanoma Cooperative Group

Thirty-nine patients with measurable advanced malignant melanoma were entered in a phase II trial with PALA. Among the 36 evaluable patients there were 18 men and 18 women, with a median age of 53 yr (29-73) and a median performance status (Karnofsky) of 100 (50-100). Indicator lesion consisted essentially of soft tissue lesions (29 patients) and/or lung metastases (9 patients). Only three patients had received prior chemotherapy. PALA was given as a 60-min i.v. infusion at a daily dose of 2.5 g/m2 for two consecutive days. Courses were repeated every two weeks. A median number of 3 courses (2-8) were administered. Partial response (greater than 50%) was obtained in 4 patients for 6-17 weeks. Eight patients had stable disease after 3 courses of PALA and 24 had progressive disease. Toxic effects were generally mild to moderate and mainly included cutaneous toxicity, nausea and vomiting, stomatitis, and diarrhea. Myelosuppression was rare and negligible. It is concluded that PALA given at the dose schedule selected for this trial is fairly well tolerated and has borderline antitumor activity in good-risk patients with advanced malignant melanoma.

Neurotoxicity of the pyrimidine synthesis inhibitor N-phosphonoacetyl-L-aspartate

PALA (N-phosphonoacetyl-L-aspartate) impairs de novo pyrimidine biosynthesis by inhibiting the enzyme aspartate transcarbamylase. During cancer chemotherapy trials the drug was given by weekly intravenous infusion. Seizures developed in 9 (11%) of the first 80 patients to receive a total dose of 9 gm/m2 or more. Seven of the affected patients had structural brain lesions; they developed seizures at a lower total dose (median of 16.4 gm/m2) than the 2 patients without clinically detectable brain lesions (115 to 130 gm/m2). Reversible encephalopathy was observed in 6 (7.5%) additional patients without clinically detectable cause other than PALA. Both seizures and encephalopathy began after the second dose of PALA or later. Experiments in rats demonstrated similar delayed-onset seizures after two or three combined systemic and intracerebral doses of PALA at 4-day intervals. Concurrent administration of uridine or carbamyl aspartate prevented the development of seizures in rats, indicating that pyrimidine starvation of the central nervous system was responsible for PALA neurotoxicity.

Phase I-phase II trial of N-phosphonacetyl-L-aspartic acid given by intravenous infusion and 5-fluorouracil given by bolus injection

A phase I clinical trial of N-phosphonacetyl-L-aspartic acid (PALA) and 5-fluorouracil (FUra) was performed on 30 patients. PALA was given as a 15-minute iv infusion once daily for 5 days, and FUra was given as a bolus injection on days 2, 3, 4, and 5. Cycles of treatment were repeated every 3 weeks. Dose-limiting toxicity was manifested by stomatitis and diarrhea. Skin rash was observed also but was not dose limiting. No consistent hematopoietic or renal toxicity was observed. Seventeen patients with disseminated metastatic melanoma and measurable disease were evaluated for response. One partial response was seen; however, the response was associated with significant toxicity, and the treatment could not be repeated. Stable disease was observed in 3 patients with melanoma, 1 patient with colon carcinoma, and 1 patient with ovarian carcinoma. Our findings suggest that the clinical activity of PALA and FUra given according to the above schedule for melanoma is less than 25% (P less than 0.05). Pharmacokinetic studies of FUra revealed no consistent effect of PALA pretreatment on FUra disappearance in plasma. The mean FUra elimination half-line in plasma was 7.11 +/- 0.84 minutes (SEM), which is no different from that reported for FUra alone. The recommended doses on this schedule for phase II studies are 1,000 mg PALA/m2/day iv daily for 5 days and 200 mg FUra/m2/day iv on days 2, 3, 4, and 5.

Phase II trial of combination therapy with continuous-infusion PALA and bolus-injection 5-FU

Fifty-seven patients were treated with continuous infusion of PALA at a dose of 850 mg/m2/day x 5 and iv bolus injection of 5-FU at a dose of 300 mg/m2/day x 5, which was given at the end of each 24-hour PALA infusion; the treatment interval was 28 days. The overall response rate among 43 evaluable patients was 14%. Two of 21 patients (10%) with colorectal carcinoma, two of eight patients with pancreatic carcinoma, and two of four patients with breast carcinoma achieved partial responses lasting 2-12 months. One of the responding patients with colon cancer and two with breast cancer had failed to respond to prior therapy with 5-FU; one of the responding patients with breast cancer had previously received an inadequate trial of a similar regimen. Toxic effects were mild to moderate and were confined to oral mucositis in most patients. It is concluded that this regimen offers little enhancement of the antitumor activity of 5-FU in patients with colorectal cancer previously treated with 5-FU. Investigation of other infusion techniques for the PALA and 5-FU combination is recommended, with particular attention to the treatment of colorectal, pancreatic, and breast carcinomas.

N-(phosphonacetyl)-L-aspartate (PALA) in advanced soft tissue sarcoma: a phase II trial of the EORTC soft tissue sarcoma group

Thirty-six patients with measurable or evaluable advanced soft tissue sarcoma were entered in a phase II trial with PALA. Among the 27 evaluable patients, 15 were men, the median age was 55 yr (16-69) and the median performance status (Karnofsky) was 80 (50-100). Most patients had leiomyosarcoma (8), liposarcoma (3), neurofibrosarcoma (3), synovial cell sarcoma (3), or undifferentiated sarcoma (3). Indicator lesions consisted essentially of lung metastases (21) and/or soft tissue lesions (14). All patients had received prior chemotherapy with 1-5 regimens and 6 had achieved objective response with these previous treatments. PALA was given as a 60-min i.v. infusion at a daily dose of 2.5 g/m2 for two consecutive days. Courses were repeated every two weeks. A median number of 3 courses (2-17) were administered. Partial remission (greater than 50%) was obtained in one patient with a liposarcoma who had also responded to prior combination chemotherapy. This single response to PALA lasted 6 weeks from initiation of therapy. Four patients had unchanged disease after 6+ courses of PALA and 22 had progressive disease. Toxic effects were generally mild to moderate and included cutaneous toxicity (17), diarrhea (14), stomatitis (13), ocular manifestations, consisting of conjunctivitis, corneal ulceration and/or photophobia (11), nausea and vomiting (6) and, possibly, seizures (2). There was no evidence of drug-related myelosuppression. It is concluded that PALA given at the dose schedule selected for this trial has no significant antitumor activity in advanced soft tissue sarcoma previously treated with chemotherapy.

N-(phosphonacetyl)-L-aspartate (PALA) in advanced breast cancer: a phase II trial of the EORTC breast cancer cooperative group

Twenty-nine evaluable patients with extensively pretreated breast cancer received PALA, a new pyrimidine antimetabolite. The drug was given by intravenous infusion over 60 min, at a daily dose of 2.5 g/m2 for 2 consecutive days. Courses were repeated at 2-week intervals and doses were escalated to toxicity. Two objective partial remissions were observed, lasting for 3 and 4.5 months respectively. Toxic effects were dose-related and consisted mainly of mucocutaneous manifestations, i.e., skin rashes, stomatitis, diarrhea, conjunctivitis and corneal ulcerations. Evidence of antitumor potential in far-advanced disease and lack of myelosuppression point to the need for additional trials of PALA in a more favorable selection of patients with breast cancer.

Chemotherapy for colorectal cancer with a combination of PALA and 5-FU

Fifty-one previously untreated patients with advanced, measurable colorectal cancer were randomized to receive single doses of PALA and 5-FU either weekly (24 patients) or daily for 5 days every 4 weeks (27 patients). In both schedules the daily dose of PALA was administered iv over 1 hour, while the dose of 5-FU was administered iv over 30 minutes, starting 3 hours after completion of the PALA dose. Doses of both drugs were changed simultaneously, based on toxic effects. Partial responses were seen in four of 24 evaluable patients receiving the weekly regimen and in three of 26 patients receiving the 5-day regimen. Skin rash, mucositis, and diarrhea were the dose-limiting toxic effects in both treatment regimens. These toxic effects were more common and severe at higher doses and on the weekly schedule. Myelosuppression was mild and moderate, the doses and schedules used in this study did not significantly increase the activity of 5-FU. Further evaluation of these doses and schedules for activity against colorectal cancer is not warranted.

A possible role for aspartic acid in neonatal seizures

Aspartic acid concentration in CSF was markedly elevated in a newborn infant with severe, intractable seizures. The levels of all other amino acids in blood, urine, and CSF were within the normal range. Two of the six other siblings in this consanguineous family died in early infancy of a similar condition. Since aspartic acid is a putative excitatory neurotransmitter, a possible causal relationship is suggested between its increased CSF concentration and the occurrence of neonatal convulsions in this family.