Gamma Secretase Inhibition Sensitizes Pancreatic Adenocarcinoma Tumors to RT In Vivo

PURPOSE/OBJECTIVE(S)

Pancreatic adenocarcinoma (PDAC) is an extremely aggressive cancer that lacks curative treatment options. Almost half of patients present with unresectable disease limiting treatment to non-curative options. Patients treated with neoadjuvant radiation therapy (RT) exhibit increases in fibrosis and epithelial-to-mesenchymal transition (EMT). ADAM10, an extracellular sheddase, can stimulate stromal fibrosis, EMT, and radioresistance. ADAM10 also mediates EMT through Notch signaling by cleaving its extracellular domain. Further cleavage by gamma secretase produces the Notch intracellular domain (NICD), which translocates to the nucleus and activates downstream transcriptional targets. Here, we explore whether inhibition of Notch cleavage by gamma secretase radiosensitizes PDAC tumors.

MATERIALS/METHODS

Bilateral flank subcutaneous PDAC isografts were produced in 40 mice using PK5L1940 KPC cells. Intraperitoneal injections of the gamma secretase inhibitor, DAPT (5 mg/kg), were delivered daily for 7 days, starting 3 days prior to RT. A single dose of 20 Gy was administered to each flank tumor, and volumes were measured twice weekly. Colony formation assays of KPC cells were performed after RT, in the presence or absence of DAPT. Since stromal fibrosis can mediate radio-resistance in the tumor microenvironment (TME), the effect of tumor cells on Notch pathway activation in mouse fibroblasts (3T3 cells) was investigated using a luciferase reporter assay. Thus, 3T3 cells transfected with a Notch pathway luciferase reporter were incubated with PDAC cells for 48 h, followed by measurement of luciferase activity.

RESULTS

In vivo, the combination of DAPT and RT significantly delayed tumor growth, and some tumors were completely eradicated. Mean tumor size for the combination at 21 days was 21 mm3 (range = 0-53, p = 0.005), while tumor size was 577 mm3 (range = 217-955, p = 0.69) for DAPT alone, 435 mm3 for RT alone (range = 51-932, p = 0.79), and 367 mm3 for untreated vehicle (range = 97-1144). Surprisingly, DAPT did not reduce clonogenic survival in vitro. Both ADAM10 knockout and DAPT decreased NICD cleavage and transcription of the downstream target Hes1 in vivo and in vitro. Co-culture with PDAC cells increased Notch luciferase reporter activity in fibroblasts. This effect was not mimicked by PDAC-conditioned media, suggesting a requirement for intercellular contact.

CONCLUSION

Notch pathway inhibition sensitizes PDAC tumors to RT in vivo, but not in vitro, suggesting involvement of the TME. Indeed, co-culture with PDAC cells stimulates notch signaling in fibroblasts, suggesting non-cell autonomous mechanisms mediating fibrosis in the TME driving radioresistance. Future studies will determine if ADAM10 inhibition targeting PDAC cells and/or gamma secretase inhibition targeting the TME enhances radiation sensitivity in vivo by blocking fibroblast Notch signaling.

Impact of COVID-19 lockdown on ambient noise levels in seven metropolitan cities of India

The paper analyzed the impact of lockdown on the ambient noise levels in the seventy sites in the seven major cities of India and ascertained the noise scenario in lockdown period, and on the Janta Curfew day in comparison to the pre-lock down period and year 2019 annual average values. It was observed that the majority of the noise monitoring sites exhibited a decrement in ambient day and night equivalent noise levels on the national Janta Curfew day and Lockdown period as compared with the normal working days attributed to the restricted social, economical, industrial, urbanization activity and reduced human mobility. A mixed pattern was observed at a few sites, wherein the ambient day and night equivalent noise levels during Janta curfew day and Lockdown period had been reported to be higher than that on the normal working days. The study depicts the noise scenario during the lockdown and pre-lockdown period for seventy sites in India and shall be instrumental in analyzing the consequences and implications of imposing lockdowns in future on the environmental noise pollution in Indian cities.

The experiences of NHS hospital acute medicine departments in England during the first wave of the COVID-19 pandemic

We conducted a survey exploring the experiences of NHS hospital acute medicine services in England during the 1st wave of the COVID-19 pandemic. Responses were collected from 26th May to 8th July 2020. The results of 91 sites are presented. The total number of patients referred to the medical take for assessment and admitted from the medical take decreased from pre-pandemic levels compared to peak COVID-19 activity. The total number of acute medical beds decreased, however critical care beds increased by 162%. We report the median timeline from first admission of COVID-19 to when baseline critical care capacity was reached. We found regional variation across the results. These findings can assist healthcare leaders prepare for future pandemics.

Physiotherapy rehabilitation for osteoporotic vertebral fracture-a randomised controlled trial and economic evaluation (PROVE trial)

The trial compared three physiotherapy approaches: manual or exercise therapy compared with a single session of physiotherapy education (SSPT) for people with osteoporotic vertebral fracture(s). At 1 year, there were no statistically significant differences between the groups meaning there is inadequate evidence to support manual or exercise therapy.

INTRODUCTION

To evaluate the clinical and cost-effectiveness of different physiotherapy approaches for people with osteoporotic vertebral fracture(s) (OVF).

METHODS

>Prospective, multicentre, adaptive, three-arm randomised controlled trial. Six hundred fifteen adults with back pain, osteoporosis, and at least 1 OVF participated.

INTERVENTIONS

7 individual physiotherapy sessions over 12 weeks focused on either manual therapy or home exercise compared with a single session of physiotherapy education (SSPT). The co-primary outcomes were quality of life and back muscle endurance measured by the QUALEFFO-41 and timed loaded standing (TLS) test at 12 months.

RESULTS

At 12 months, there were no statistically significant differences between groups. Mean QUALEFFO-41: - 1.3 (exercise), - 0.15 (manual), and - 1.2 (SSPT), a mean difference of - 0.2 (95% CI, - 3.2 to 1.6) for exercise and 1.3 (95% CI, - 1.8 to 2.9) for manual therapy. Mean TLS: 9.8 s (exercise), 13.6 s (manual), and 4.2 s (SSPT), a mean increase of 5.8 s (95% CI, - 4.8 to 20.5) for exercise and 9.7 s (95% CI, 0.1 to 24.9) for manual therapy. Exercise provided more quality-adjusted life years than SSPT but was more expensive. At 4 months, significant changes above SSPT occurred in endurance and balance in manual therapy, and in endurance for those ≤ 70 years, in balance, mobility, and walking in exercise.

CONCLUSIONS

Adherence was problematic. Benefits at 4 months did not persist and at 12 months, we found no significant differences between treatments. There is inadequate evidence a short physiotherapy intervention of either manual therapy or home exercise provides long-term benefits, but arguably short-term benefits are valuable.

TRIAL REGISTRATION

ISRCTN 49117867.

The phosphoinositide-3-kinase (PI3K)-delta and gamma inhibitor, IPI-145 (Duvelisib), overcomes signals from the PI3K/AKT/S6 pathway and promotes apoptosis in CLL

The functional relevance of the B-cell receptor (BCR) and the evolution of protein kinases as therapeutic targets have recently shifted the paradigm for treatment of B-cell malignancies. Inhibition of p110δ with idelalisib has shown clinical activity in chronic lymphocytic leukemia (CLL). The dynamic interplay of isoforms p110δ and p110γ in leukocytes support the hypothesis that dual blockade may provide a therapeutic benefit. IPI-145, an oral inhibitor of p110δ and p110γ isoforms, sensitizes BCR-stimulated and/or stromal co-cultured primary CLL cells to apoptosis (median 20%, n=57; P<0.0001) including samples with poor prognostic markers, unmutated IgVH (n=28) and prior treatment (n=15; P<0.0001). IPI-145 potently inhibits the CD40L/IL-2/IL-10 induced proliferation of CLL cells with an IC50 in sub-nanomolar range. A corresponding dose-responsive inhibition of pAKT(Ser473) is observed with an IC50 of 0.36 nM. IPI-145 diminishes the BCR-induced chemokines CCL3 and CCL4 secretion to 17% and 37%, respectively. Pre-treatment with 1 μM IPI-145 inhibits the chemotaxis toward CXCL12; reduces pseudoemperipolesis to median 50%, inferring its ability to interfere with homing capabilities of CLL cells. BCR-activated signaling proteins AKT(Ser473), BAD(Ser112), ERK(Thr202/Tyr204) and S6(Ser235/236) are mitigated by IPI-145. Importantly, for clinical development in hematological malignancies, IPI-145 is selective to CLL B cells, sparing normal B- and T-lymphocytes.

Destructive spondyloarthropathy in a haemodialysis patient with HIV infection: case report and literature review

This case describes the presentation, diagnosis and treatment of a 59-year-old man with medical history of HIV/AIDS and hepatitis C on haemodialysis for end stage renal disease who presented with debilitating neck pain radiating down to the left arm with associated weakness of left upper and lower extremities. He had received a prolonged course of intravenous antibiotics for similar complaints. His initial presentation, coupled with the history of recent antibiotics, triggered a non-infectious work-up and the patient was diagnosed with destructive spondyloarthropathy, a rare but under-diagnosed complication of patients on long-term haemodialysis. This was confirmed on imaging studies. The patient refused surgical intervention, and was treated conservatively. With improved survival of patients with HIV infection, other significant co-morbidities like end stage renal disease and their potential complications in these patients have become an increasing focus of attention. Destructive spondyloarthropathy is a severely debilitating condition and can be potentially fatal. The aetiopathogenesis, management and ethical and legal implications of HIV patients with destructive spondyloarthropathy secondary to long-term haemodialysis are discussed.

Distribution of small integrin-binding ligand, N-linked glycoproteins (SIBLING) in the condylar cartilage of rat mandible

The Small Integrin-Binding LIgand, N-linked Glycoprotein (SIBLING) family is one category of non-collagenous proteins closely related to osteogenesis. In this study, the authors systematically evaluated the presence and distribution of four SIBLING family members, dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), bone sialoprotein (BSP) and osteopontin (OPN), in rat mandibular condylar cartilage using protein chemistry and immunohistochemistry. For protein chemistry, SIBLING proteins in the dissected condylar cartilage were extracted with 4M guanidium-HCl, separated by ion-exchange chromatography, and analyzed by Western immunoblotting. Immunohistochemistry was employed to assess the distribution of these four SIBLING proteins in the condylar cartilage of 2-, 5- and 8-week-old rats. Results from both approaches showed that all four members are expressed in the condylar cartilage. DSPP, unlike that observed in dentin and bone, exists as a full-length form (uncleaved) in the condylar cartilage. The NH(2)-terminal fragment of DMP1 is mainly detected in the matrix of the cartilage while the COOH-terminal fragment is primarily localized in the nuclei of cells in the chondroblastic and hypertrophic layers. The data obtained in this investigation provide clues about the potential roles of these SIBLING proteins in chondrogenesis.

Results of a phase I study of clofarabine (CLO) plus cyclophosphamide (CY) in adult patients (pts) with relapsed and/or refractory acute lymphoblastic leukemia (ALL)

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Background: CLO is a second generation nucleoside analog with FDA approval for children with ALL relapse. Single agent CLO in adult ALL was less active so that combinations of CLO with other active agents are pursued. As CLO inhibits DNA repair following exposure to DNA damaging agents, we designed a phase I study of the combination of CLO with CY. Methods: Pts ≥ 21 years (yrs) with primary refractory or relapsed ALL, NYHA class < 3, and a cardiac ejection fraction ≥ 45% were eligible. The continual reassessment method (CRM) was used to determine the maximum tolerated dose (MTD) from 4 pre-defined dose levels. The starting dose level was CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. For cohort 2, CY was 300 mg/m2 and cohorts 3 and 4 maintained these doses with the treatment duration extended to 4 and 5 days, respectively. Results: Thirty pts have been enrolled. Median age was 28 yrs (range 21–72). Twenty-one pts had pre-B ALL, 5 pts pre-T/T ALL, 1 pt mature B ALL, and 3 pts biphenotypic acute leukemias. Karyotype was diploid in 10 pts and 2 pts had Ph+ ALL. Median number of prior regimens was 2 (1–5). Seven (23%) pts were primary refractory. Among the remainder, preceding median remission duration was 8.6 mos (1–39 mos). Five pts were treated in cohort 1 and 25 in cohort 2. One (20%) pt in cohort 1 and 9 (36%) in cohort 2 experienced DLTs (≥ grade 3) including transaminase elevations, diarrhea, hyperbilirubinemia, and (1 pt each) elevation of creatinine/renal failure, lipase elevation, rash, nausea/vomiting. Evaluable for response were 28 pts: 3 CR (one pt in cohort 1) and 1 marrow CR (OR 14%). All pts had pre-B ALL. One pt had Ph+ ALL, and one was primary refractory to HCVAD. Three early deaths due to infectious complications occurred (all in cohort 2). Conclusions: The MTD for this combination is CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. DLT are mainly GI-related. A phase II extension is ongoing and will focus on efficacy data.

[Table: see text]

Phase I study of 506U78 administered on a consecutive 5-day schedule in children and adults with refractory hematologic malignancies

PURPOSE

A phase I study was conducted to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetics of a novel purine nucleoside, nelarabine, a soluble prodrug of 9-beta-D-arabinosylguanine (araG; Nelarabine), in pediatric and adult patients with refractory hematologic malignancies.

PATIENTS AND METHODS

Between April 1994 and April 1997, 93 patients with refractory hematologic malignancies were treated with one to 16 cycles of study drug. Nelarabine was administered daily, as a 1-hour intravenous infusion for 5 consecutive days, every 21 to 28 days. First-cycle pharmacokinetic data, including plasma nelarabine and araG levels, were obtained on all patients treated. Intracellular phosphorylation of araG was studied in samples of leukemic blasts from selected patients.

RESULTS

The MTDs were defined at 60 mg/kg/dose and 40 mg/kg/dose daily x 5 days in children and adults, respectively. Dose-limiting toxicity (DLT) was neurologic in both children and adults. Myelosuppression and other significant organ toxicities did not occur. Pharmacokinetic parameters were similar in children and adults. Accumulation of araGTP in leukemic blasts was correlated with cytotoxic activity. The overall response rate was 31%. Major responses were seen in patients with T-cell malignancies, with 54% of patients with T-lineage acute lymphoblastic leukemia achieving a complete or partial response after one to two courses of drug.

CONCLUSION

Nelarabine is a novel nucleoside with significant cytotoxic activity against malignant T cells. DLT is neurologic. Phase II and III trials in patients with T-cell malignancies are encouraged.

The significance of a high plasma ammonia value

At a tertiary referral centre, just over 50% of patients with plasma ammonia values over 200 micro mol/l had inborn errors of metabolism. To distinguish artefactual high values from those requiring treatment, the measurement should be repeated immediately if the result is above 200 micro mol/l and at lower concentrations if the patient is encephalopathic.

Nail changes in alopecia areata: incidence and pattern

One hundred consecutive patients with alopecia areata were examined for presence of nail abnormalities. Nail changes were seen in 44/100 (44%) of patients with most frequent occurrence in multifocal variety (30/44=68%). The commonest abnormality observed was superficial pits seen in 28 (64%) patients. Presence and severity of nail changes may indicate a more severe and recalcitrant disease.

Treatment of Schamberg's disease with pentoxifylline--therapeutic trial

Twenty patients with Schamberg's disease were started on pentoxifylline (400 mg once daily) for a period of 8 weeks. Improvement was assessed at 2 weekly intervals by two observers independently and graded as mild (< 25%, moderate (25-50%) and marked (>50%). Marked improvement was observed in 10/20(50%) patients. We conclude that pentoxifylline should be considered as first line therapy in all patients with Schamberg's disease.

Gemcitabine in hematologic malignancies

Gemcitabine is a pyrimidine analogue that showed significant activity in solid malignancies. Gemcitabine acts by inhibiting DNA synthesis through chain termination and ribonucleotide reductase inhibition. During initial phase I and II studies, gemcitabine had a low toxicity profile and was well tolerated as a single agent and in combination therapy. Recently, there has been more interest in studying the activity of gemcitabine in hematologic malignancies. Gemcitabine demonstrated good activity in refractory Hodgkin disease patients, non-Hodgkin lymphoma, cutaneous T-cell lymphoma, and acute leukemias. There is a preponderance of evidence on the activity of gemcitabine in vitro in myeloma and leukemic cell lines. The activity of gemcitabine in these disorders will pave the way for incorporating this agent into the early phases of therapy.

Phase II clinical investigation of gemcitabine in advanced soft tissue sarcomas and window evaluation of dose rate on gemcitabine triphosphate accumulation

PURPOSE

To evaluate the efficacy, toxicity, and optimal dose rate of gemcitabine in adult patients with advanced soft tissue sarcomas (STS) by comparing levels of gemcitabine triphosphate (GTP) in peripheral-blood mononuclear cells (PBMCs) of patients receiving two different dose rates.

PATIENTS AND METHODS

Fifty-six assessable patients with STS (17 gastrointestinal [GI] leiomyosarcomas and 39 other histologies) were treated on a two-arm phase II study. Gemcitabine was given at 1 g/m2 as a 30-minute infusion weekly for up to 7 weeks followed by 1 week of rest and reassessment of tumor. Subsequent cycles were given at 1 g/m2 weekly for 3 weeks followed by 1 week of rest. Nine patients underwent cellular pharmacologic studies at two different dose rates (1 g/m2 over a standard 30-minute infusion on week 1 and over pharmacologically based infusion of 150 minutes on week 2) to evaluate GTP levels in PBMCs.

RESULTS

Seven partial responses were noted among 39 patients, for an overall response rate of 18% (95% confidence interval, 7% to 29%). Median duration of response was 3.5 months (range, 2 to 13 months). Four of 10 patients with non-GI leiomyosarcomas achieved a partial response. No objective responses were noted in 17 patients with GI leiomyosarcomas. One patient had a mixed response. Median time to progression for all patients (both arms) was 3 months; median survival was 13.9 months. Treatment was generally well tolerated. Comparison of cellular pharmacology demonstrated a significant 1.4-fold increase in the concentration of GTP with the 150-minute infusion.

CONCLUSION

Given the limited therapeutic armamentarium for STS, the activity of gemcitabine is encouraging. Its potential for combination therapy in the salvage setting should be studied with pharmacologically guided fixed dose-rate infusion.

8-chloro-cAMP and 8-chloro-adenosine act by the same mechanism in multiple myeloma cells

Previous work with 8-chloro-cAMP (8-Cl-cAMP) has raised questions as to whether it works as a cAMP analogue or as a nucleoside analogue after its conversion to 8-chloro-adenosine (8-Cl-Ado). Although degradation of 8-Cl-cAMP to 8-Cl-Ado in culture medium or plasma has been shown, cellular pharmacology data are missing. The purpose of the present study was to identify the cellular metabolism of these drugs and their actions in a human multiple myeloma cell line. The cells were incubated with either 8-Cl-Ado or 8-Cl-cAMP to follow the cellular metabolism of these agents. Both 8-Cl-cAMP and 8-Cl-Ado incubation resulted in the accumulation of 8-Cl-Ado mono-, di-, and tri-phosphate (8-Cl-ATP), however, the triphosphate was the major cytotoxic metabolite. Accumulation of 8-Cl-ATP was dependent on both the exogenous concentration of 8-Cl-Ado and incubation time. At the 10 microM level of 8-Cl-Ado, >400 microM 8-Cl-ATP accumulated in multiple myeloma cells after continuous incubation for 12 h. Similar incubation with 8-Cl-cAMP also resulted in accumulation of 8-Cl-ATP in the cells, albeit at a lower level. The formation of 8-Cl-ATP from 8-Cl-cAMP was inhibited by >80% in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine in the medium, suggesting extracellular conversion of 8-Cl-cAMP to 8-Cl-Ado. Cells lacking Ado kinase did not accumulate 8-Cl-ATP, either from 8-Cl-Ado or 8-Cl-cAMP, and were resistant to these agents. There was also a decline in the endogenous level of the cellular ATP pool parallel to the accumulation of 8-C1-ATP. The elimination of 8-Cl-ATP was biphasic and slow from the cells. The accumulation of 8-Cl-ATP and a decline in the ATP pool inhibited RNA synthesis but did not affect DNA synthesis for up to 12 h of incubation. Taken together, these data demonstrate that the cytotoxic metabolite of 8-Cl-Ado and 8-Cl-cAMP is 8-Cl-ATP. Hence, 8-Cl-cAMP serves as a prodrug and is converted to 8-Cl-Ado in medium with subsequent phosphorylation to accumulate as 8-Cl-ATP in cells. At the cellular level, 8-Cl-ATP is associated with a decrease in the endogenous ATP pool; at the nuclear level, it inhibits RNA synthesis.

Evaluation of the combination of nelarabine and fludarabine in leukemias: clinical response, pharmacokinetics, and pharmacodynamics in leukemia cells

PURPOSE

A pilot protocol was designed to evaluate the efficacy of fludarabine with nelarabine (the prodrug of arabinosylguanine [ara-G]) in patients with hematologic malignancies. The cellular pharmacokinetics was investigated to seek a relationship between response and accumulation of ara-G triphosphate (ara-GTP) in circulating leukemia cells and to evaluate biochemical modulation of cellular ara-GTP metabolism by fludarabine triphosphate.

PATIENTS AND METHODS

Nine of the 13 total patients had indolent leukemias, including six whose disease failed prior fludarabine therapy. Two patients had T-acute lymphoblastic leukemia, one had chronic myelogenous leukemia, and one had mycosis fungoides. Nelarabine (1.2 g/m(2)) was infused on days 1, 3, and 5. On days 3 and 5, fludarabine (30 mg/m(2)) was administered 4 hours before the nelarabine infusion. Plasma and cellular pharmacokinetic measurements were conducted during the first 5 days.

RESULTS

Seven patients had a partial or complete response, six of whom had indolent leukemias. The disease in four responders had failed prior fludarabine therapy. The median peak intracellular concentrations of ara-GTP were significantly different (P =.001) in responders (890 micromol/L, n = 6) and nonresponders (30 micromol/L, n = 6). Also, there was a direct relationship between the peak fludarabine triphosphate and ara-GTP in each patient (r = 0.85). The cellular elimination of ara-GTP was slow (median, 35 hours; range, 18 to > 48 hours). The ratio of ara-GTP to its normal counterpart, deoxyguanosine triphosphate, was higher in each patient (median, 42; range, 14 to 1,092) than that of fludarabine triphosphate to its normal counterpart, deoxyadenosine triphosphate (median, 2.2; range, 0.2 to 27).

CONCLUSION

Fludarabine plus nelarabine is an effective, well-tolerated regimen against leukemias. Clinical responses suggest the need for further exploration of nelarabine against fludarabine-refractory diseases. Determination of ara-GTP levels in the target tumor population may provide a prognostic test for the activity of nelarabine.

Porphyrins with exocyclic rings. 15.(1) synthesis of quino- and isoquinoporphyrins, aza analogues of the naphthoporphyrins

Porphyrins with fused isoquinoline and quinoline units have been prepared by the "3 + 1" methodology. 5-Nitroisoquinoline and 6-nitroquinoline condensed with ethyl isocyanoacetate in the presence of a phosphazene base to give isoquino- and quinopyrroles, respectively. Ester saponification and decarboxylation with KOH in ethylene glycol at 190 degrees C gave the parent azatricycles, and these were further condensed with 2 equiv of an acetoxymethylpyrrole to give the corresponding tripyrranes protected at the terminal positions as their tert-butyl esters. In a one-pot procedure, the ester protective groups were cleaved with TFA, and following dilution with dichloromethane, "3 + 1" condensation with a pyrrole dialdehyde and dehydrogenation of the phlorin intermediate with DDQ gave the targeted azanaphthoporphyrins in excellent yields. Although the UV-vis spectra of these new porphyrin systems are unexceptional, they show promise for further functionalization and applications in the development of porphyrin arrays. In addition, a zinc chelate of the isoquinoporphyrin system shows a high degree of regioselective intermolecular interaction/aggregation in chloroform solution that may lead to selectivity in molecular recognition studies.

High-performance liquid chromatography method for the determination and quantitation of arabinosylguanine triphosphate and fludarabine triphosphate in human cells

A gradient anion-exchange high-performance liquid chromatographic assay was developed for the simultaneous determination and quantitation of the cytotoxic triphosphates of arabinosylguanine (ara-GTP) and fludarabine (F-ara-ATP). The method was validated with respect to selectivity, recovery, linearity, precision, and accuracy using authentic standards. To test this assay in a more complex biological matrix, perchloric acid extracts of circulating human leukemia cells spiked with known concentrations of ara-GTP and F-ara-ATP were examined. Finally, to assess the clinical utility of our method, perchloric acid extracts of circulating human leukemia cells isolated from patients treated with fludarabine and nelarabine were analyzed. The range of quantitation was 0.0125-10 nmol for the ara- and native NTPs in cellular extracts. This assay should be helpful in establishing the mechanistic rationales for drug scheduling and combinations of nelarabine and fludarabine, and for correlating the therapeutic efficacy and levels of the cytotoxic triphosphates in target cells.

Pharmacokinetics of nelarabine and 9-beta-D-arabinofuranosyl guanine in pediatric and adult patients during a phase I study of nelarabine for the treatment of refractory hematologic malignancies

PURPOSE

To characterize the pharmacokinetics of nelarabine (506U78), the water-soluble prodrug of 9-beta-D-arabinofuranosyl guanine (ara-G), and ara-G in pediatric and adult patients with refractory hematologic malignancies. Ara-G is phosphorylated within leukemic cells to form ara-G triphosphate (ara-GTP), which acts to terminate DNA chain elongation, resulting in cell death.

PATIENTS AND METHODS

The pharmacokinetics of nelarabine and/or ara-G were evaluated in 71 patients (25 pediatric and 46 adult patients) on the first day of therapy. Blood was collected at specified times for the determination of plasma nelarabine and ara-G concentrations.

RESULTS

There were no statistically significant differences in the pharmacokinetics of nelarabine between any of the groups of patients. The harmonic mean half-life (t1/2) of nelarabine in pediatric and adult patients was 14.1 minutes and 16.5 minutes, respectively. The maximum concentrations (C(max)) of ara-G occurred at or near the end of the nelarabine infusion. The C(max) of ara-G ranged from 11.6 micromol/L to 308.7 micromol/L at nelarabine doses of 5 to 75 mg/kg and was linearly related to the nelarabine dose. No statistically significant differences were noted for the pharmacokinetic parameter estimates of ara-G between adult male and female patients. In children versus adults, the dose-normalized C(max), time of the C(max), and the steady-state volume of distribution of ara-G were similar. However, the clearance of ara-G was higher in pediatric patients (0.312 L.h(-1).kg(-1)) as compared with adult patients (0. 213 L.h(-1).kg(-1)) (P <.001). The t1/2 of ara-G was shorter in pediatric patients as compared with adult patients (2.1 hours v 3.0 hours; P <.01).

CONCLUSION

Nelarabine is an effective prodrug of ara-G, allowing systemic concentrations of ara-G that result in clinical activity.

Sequential cis-platinum and fludarabine with or without arabinosyl cytosine in patients failing prior fludarabine therapy for chronic lymphocytic leukemia: a phase II study

Patients with chronic lymphocytic leukemia (CLL) who fail fludarabine (Fluda) therapy have a poor response to subsequent salvage regimens and a poor prognosis. This study was undertaken to determine the efficacy and toxicity of a cis-platinum, (cis-p)fluda and arabinosyl cytosine (ara-C) combination in patients who were refractory to fluda or had relapsed following prior fluda therapy for CLL. Forty-one patients who had progressive CLL were treated on study. Eleven patients (27%) were sensitive to fluda and thirty (73%) refractory prior to study entry. Therapy consisted of cis-p 100 mg/m2 continuous intravenous (i.v.) infusion over 4 days, fluda 30 mg/m2 i.v. over 15 minutes on Days 3 and 4 either given alone (PF) or with ara-C 500 mg/m2 i.v. over 1 hour on Day 4 (PFA). The median number of PF or PFA courses received was two. No patient achieved a complete response. Eight patients (19%) achieved a partial response (PR), 28 were taken off study with progressive or refractory disease and 5 had induction deaths. The overall median survival was 6 months, 15 months in responding patients, and 4 months in non-responding patients. Rai stage I-II patients had a median survival of 7 months and stage III-IV patients had a median survival of 3 months. Major toxicities (myelosuppression, sepsis, renal failure and tumor lysis syndrome) were frequent. In conclusion, it can be said that the PF and PFA regimens have equivalent modest activity in patients with progressive CLL following prior fluda therapy, predominantly among patients whose disease was sensitive to fluda at last prior exposure. Ara-C did not add to the activity of the cis-p/fluda combination in this study group.

Arabinosylguanine-induced apoptosis of T-lymphoblastic cells: incorporation into DNA is a necessary step

9-Beta-D-Arabinosylguanine (ara-G) is a recently introduced and effective treatment for T-cell acute lymphoblastic leukemia, but how ara-G and ara-G triphosphate (ara-GTP) kill cells is not known. We hypothesized that, in cycling T-lymphoblastoid cells, ara-G may act directly by incorporation into DNA, which may lead to apoptosis. Hence, blocking the incorporation of ara-G monophosphate (ara-GMP) into DNA may prevent apoptosis. To test this hypothesis, we performed experiments in a T-lymphoblastic leukemia cell line (CCRF-CEM) after synchronization with a double aphidicolin block. Intracellular accumulation of ara-GTP was neither cell cycle dependent nor affected by aphidicolin (53 +/- 5 microM/h without aphidicolin, 50 +/- 5 microM/h with aphidicolin). Cells at the G1-S boundary accumulated 75 +/- 7 microM ara-GTP with minimal incorporation into DNA (5 +/- 2 pmol ara-GMP/mg DNA) and had little biochemical or morphological evidence of apoptosis. In marked contrast, cells in S phase had significantly more ara-G incorporated into DNA (24 +/- 4 pmol ara-GMP/mg DNA), although the cytosolic concentration of ara-GTP (85 +/- 7 microM) was similar to that in the G1-enriched population. In the S-phase cells, there was a corresponding increase in apoptosis (measured as high molecular weight DNA fragmentation and morphological changes), and the incorporation of ara-GTP into DNA resulted in a >95% inhibition of DNA synthesis. There was a direct linear relationship between the number of cells in S phase and both the total number of ara-GMP molecules in DNA and the inhibition of DNA synthesis. Blocking of ara-GTP incorporation into S-phase DNA abolished biochemical and morphological features of apoptosis, even in the presence of cytotoxic level of intracellular ara-GTP. Taken together, these data demonstrate that the incorporation of ara-GTP into DNA is the critical event that mediates the induction of apoptosis in CCRF-CEM cells.

Common resistance mechanisms to deoxynucleoside analogues in variants of the human erythroleukaemic line K562

Resistant variants of the human leukaemic line K562 were developed using selection with the deoxynucleoside analogues cytosine arabinoside, 2-chlorodeoxyadenosine, fludarabine and gemcitabine. The resistant lines displayed a high degree of cross resistance to all deoxynucleoside analogues, with little or no cross resistance to other agents. There was a profound accumulation defect of all nucleoside analogues in the resistant variants but no significant defect in nucleoside transport in any of the variants. 5' nucleotidase activity was strongly increased and deoxycytidine kinase activity was moderately reduced in all of the resistant variants, resulting in reduced accumulation of triphosphate analogues. In addition a deletion in one of the alleles of the deoxycytidine kinase was detected in the fludarabine-resistant line. Ribonucleotide reductase activity was found to be strongly increased in the gemcitabine-selected line and purine nucleoside phosphorylase was increased in the 2-chlorodeoxyadenosine-selected line. Free nucleotide pools were increased in the 2-chlorodeoxyadenosine-selected line. There was no expression of the mdr1 gene by the resistant lines. Karyotypic analysis and FISH experiments using a 6q21 specific probe showed alterations in the 6(q16-q22) region which contains the 5'-nucleotidase gene. Early events in the activation and degradation of deoxynucleoside analogues appear to constitute common mechanisms of resistance to these compounds.

Keratosis punctata palmaris et plantaris

A 30-year-old man presented with multiple keratotic papules on palms and soles. The lesions started at the age of 15 from soles. Family history was positive with members in preceding two generations being affected. Cutaneous examination revealed multiple discrete hyperkeratotic papules of variable size on palms and soles. Parakeratosis was absent in histopathology and this ruled out the diagnosis of porokeratosis punctata palmaris et plantaris.

Complete hematologic and cytogenetic response to 2-amino-9-beta-D-arabinosyl-6-methoxy-9H-guanine in a patient with chronic myelogenous leukemia in T-cell blastic phase: a case report and review of the literature

BACKGROUND

T-cell lymphoid blastic phase (BP) transformation is rare in chronic myelogenous leukemia (CML). 2-amino-9-beta-D-arabinosyl-6-methoxy-9H-guanine (GW506U78), a prodrug of arabinosylguanine (ara-G), is effective in T-cell leukemias.

METHODS

The authors present a case of a 48-year-old male with Philadelphia chromosome (Ph) positive CML and T-cell lymphoid BP after 17 months in the chronic phase.

RESULTS

Plasma pharmacokinetic studies after an infusion of GW506U78 at a dose of 40 mg/kg showed GW506U78 concentrations of 60 microM, and a peak ara-G concentration of 260 microM in the plasma. Cellular ara-G triphosphate (ara-GTP) concentration in the peripheral blood T-lymphoblasts was 80 microM at the end of GW506U78 infusion and reached a maximum of 150 microM. The patient achieved a complete response that lasted 13 months. Severe neurotoxicity related to GW506U78 was observed.

CONCLUSIONS

GW506U78 showed antileukemic activity against Ph positive T-cell BP CML. Neurotoxicity was dose-limiting in this patient. Treatment with GW506U78 and modulation of ara-GTP concentrations are therapeutic strategies that require further exploration in T-cell malignancies. Investigation of other dosing schedules may limit neurotoxicity.

Scleredema adultorum of buschke associated with non-scarring alopecia of scalp

A 3 year old boy presenting with scleredema of Buschke confirmed histopathologically is being reported for its unusual association with reversible non-cicatricial alopecia of the scalp.

Compound GW506U78 in refractory hematologic malignancies: relationship between cellular pharmacokinetics and clinical response

PURPOSE

In vitro investigations with arabinosylguanine (ara-G) demonstrated potent cytotoxicity to T-lymphoblastoid cell lines. The goals of the present study were to evaluate GW506U78, a prodrug of ara-G, against human hematologic malignancies and to determine its pharmacokinetics in plasma and cells.

PATIENTS AND METHODS

During a phase I multicenter trial of GW506U78, 26 patients were treated at M.D. Anderson Cancer Center (MDACC). Daily doses between 20 and 60 mg/kg were administered for 5 days. Parallel plasma and cellular pharmacokinetic studies were conducted.

RESULTS

Complete (n=5) or partial remission (n=5) was achieved in T-cell acute lymphoblastic leukemia (T-ALL), T-lymphoid blast crisis, T-lymphoma, and B-cell chronic lymphocytic leukemia (B-CLL) (n=13). In contrast, patients with B-ALL, B-lymphoma, acute myelogenous leukemia (AMI), or T-CLL did not respond. Peak plasma concentrations of GW506U78 and ara-G were dose-dependent. The elimination of GW506U78 (half-life [t1/2]=17 minutes) was faster than the elimination of ara-G (t1/2=3.7 hours). Median peak concentrations of ara-GTP were 23, 42, 85, and 93 micromol/L at 20, 30, 40, and 60 mg/kg, respectively. T-lymphoblasts accumulated significantly (P=.0008) higher peak arabinsylguanosine triphosphate (ara-GTP) (median, 140 micromol/L; n=7) compared with other diagnoses (median, 50 micromol/L; n=9) and normal mononuclear cells (n=3). The ara-GTP elimination was slow in all diagnoses (median, > 24 hours). Responders accumulated significantly (P=.0005) higher levels of ara-GTP (median, 157 micromol/L) compared with patients who failed to respond (median, 44 micromol/L).

CONCLUSION

GW506U78 is an effective prodrug and a potent agent for hematologic malignancies with major efficacy in T-cell diseases. The pharmacokinetics of ara-GTP in leukemia cells are strongly correlated with clinical responses to GW506U78.

Lymphangioma circumscriptum of scrotum of late onset

Lymphangioma circumscriptum is the commonest type of lymphangioma which is characterised by small, grouped vesicles resembling frog spawn. An interesting case of thin walled lymphangioma circumscriptum is reported which started at a late age of 45 years and limited to scrotum in a 70-year old man.

Eruptive mollusca contagiosa in an immunocompetent Indian adult

A 35-year old Indian woman with eruptive onset of mollusca contagiosa with no underlying immunodeficiency who responded to etretinate therapy is reported.

Papillon - lefevre syndrome with mental retardation

A 9-year old boy, born of consanguineous parents, presented with keratoderma of palms and soles associated with severe enamel hypoplasia and mental retardation. A clinical diagnosis of Papillon - Lefevre was supported by histopathology.

Cellular pharmacodynamics and plasma pharmacokinetics of parenterally infused hydroxyurea during a phase I clinical trial in chronic myelogenous leukemia

PURPOSE

To determine the maximum-tolerated dose (MTD), toxicities, and antileukemic activity of hydroxyurea (HU) administered intravenously to patients with advanced-phase chronic myelogenous leukemia (CML). Further objectives were to analyze pharmacodynamic effect on deoxynucleotides (dNTPs) and to seek relationships between the decrease in dNTP pools and inhibition of DNA synthesis in CML blasts.

PATIENTS AND METHODS

HU (8, 12, 18, 27, and 40 g/m2) was administered intravenously by a 24-hour continuous infusion to 19 adults with CML in blastic or accelerated phase. Plasma levels of HU were analyzed in all patients. To determine the role of HU in inhibiting ribonucleotide reductase, dNTP pools in the leukemia cells were quantitated. Correlations were sought with these parameters and DNA synthesis inhibition measured ex vivo by [3H]thymidine incorporation.

RESULTS

The MTD of HU given as a 24-hour infusion was 27 g/m2. The dose-limiting toxicity was mucositis. There was a significant but transient myelosuppression, with nadir counts generally seen 3 to 4 days after the dose. The steady-state concentration of HU in plasma was achieved by 6 hours, and was proportional to the dose. There was a median 57% decrease in the deoxyadenosine triphosphate (dATP) pool in circulating blasts. In contrast, deoxyguanosine triphosphate (dGTP) and pyrimidine dNTPs were not significantly affected. The extent of DNA synthesis inhibition was related to the residual concentrations of intracellular dATP.

CONCLUSION

A 24-hour infusion of HU results in significant but transient myelosuppression in advanced-phase CML. The specific decrease of intracellular dATP correlated with the inhibition of DNA synthesis in CML blasts. This pharmacodynamic action of HU provides a rationale for combination with other chemotherapeutic agents, the effects of which could be augmented by the decline in dATP pools.

Accumulation of arabinosyluracil 5'-triphosphate during arabinosylcytosine therapy in circulating blasts of patients with acute myelogenous leukemia

Arabinosylcytosine (ara-C) is the most effective nucleoside analogue for treatment of acute myelogenous leukemia. The cytotoxicity of ara-C depends on its conversion to the triphosphate ara-CTP. In plasma, a major metabolite of ara-C is its deamination product, arabinosyluracil (ara-U). Both ara-U and ara-U monophosphate have been detected in primary leukemia cells during in vitro investigations. Because other ara-U metabolites, especially the triphosphate (ara-UTP), may serve as additional effectors of cytotoxicity, the present study investigated whether ara-UTP accumulates in circulating leukemia blasts during ara-C therapy. Patients with relapsed acute myelogenous leukemia received 2- or 4-h infusions of 0.5 g/m2/h ara-C. Intracellular accumulation of ara-CTP and ara-UTP in circulating leukemia blasts from six patients was quantitated by high-pressure liquid chromatography, revealing that ara-UTP accumulated during ara-C therapy. The intracellular concentration of ara-UTP ranged from 6-50 microM and was between 2 and 10% of the accumulated ara-CTP. In circulating blasts, ara-UTP was maintained for several hours after the end of ara-C infusion. Leukemia blasts from patients (n=27) were incubated for 1-2 h with 1, 10, or 25 microM [3H]ara-C, and radiolabeled metabolites of ara-C were separated and quantitated by high-pressure liquid chromatography. Consistent with data obtained during ara-C therapy, [3H]ara-UTP also accumulated in blasts from all these patients during in vitro incubations with [3H]ara-C. The concentration of ara-UTP after 1 h of incubation ranged from 0.2-40 microM. Incubation of cells with the cytidine deaminase inhibitor tetrahydrouridine did not perturb ara-UTP accumulation, whereas incubation with the deoxycytidylate deaminase inhibitor tetrahydrodeoxyuridine suppressed ara-UTP formation from ara-C. These observations suggested that ara-UTP is generated through deamination of ara-C monophosphate to ara-U monophosphate by deoxycytidylate deaminase, followed by its phosphorylation to ara-UTP. Consistent with these results, incubation of blasts with up to 100 microM [3H]ara-U did not result in ara-UTP accumulation, indicating that ara-U is not phosphorylated directly in these cells. The present study demonstrated that circulating leukemia blasts accumulate ara-UTP during in vitro incubations with ara-C and during ara-C therapy.