Locoregional delivery of IL-13Rα2-targeting CAR-T cells in recurrent high-grade glioma: a phase 1 trial

Chimeric antigen receptor T cell (CAR-T) therapy is an emerging strategy to improve treatment outcomes for recurrent high-grade glioma, a cancer that responds poorly to current therapies. Here we report a completed phase I trial evaluating IL-13Rα2-targeted CAR-T cells in 65 patients with recurrent high-grade glioma, the majority being recurrent glioblastoma (rGBM). Primary objectives were safety and feasibility, maximum tolerated dose/maximum feasible dose and a recommended phase 2 dose plan. Secondary objectives included overall survival, disease response, cytokine dynamics and tumor immune contexture biomarkers. This trial evolved to evaluate three routes of locoregional T cell administration (intratumoral (ICT), intraventricular (ICV) and dual ICT/ICV) and two manufacturing platforms, culminating in arm 5, which utilized dual ICT/ICV delivery and an optimized manufacturing process. Locoregional CAR-T cell administration was feasible and well tolerated, and as there were no dose-limiting toxicities across all arms, a maximum tolerated dose was not determined. Probable treatment-related grade 3+ toxicities were one grade 3 encephalopathy and one grade 3 ataxia. A clinical maximum feasible dose of 200 × 106 CAR-T cells per infusion cycle was achieved for arm 5; however, other arms either did not test or achieve this dose due to manufacturing feasibility. A recommended phase 2 dose will be refined in future studies based on data from this trial. Stable disease or better was achieved in 50% (29/58) of patients, with two partial responses, one complete response and a second complete response after additional CAR-T cycles off protocol. For rGBM, median overall survival for all patients was 7.7 months and for arm 5 was 10.2 months. Central nervous system increases in inflammatory cytokines, including IFNγ, CXCL9 and CXCL10, were associated with CAR-T cell administration and bioactivity. Pretreatment intratumoral CD3 T cell levels were positively associated with survival. These findings demonstrate that locoregional IL-13Rα2-targeted CAR-T therapy is safe with promising clinical activity in a subset of patients. ClinicalTrials.gov Identifier: NCT02208362 .

Pre-clinical data supporting immunotherapy for HIV using CMV-HIV-specific CAR T cells with CMV vaccine

T cells engineered to express HIV-specific chimeric antigen receptors (CARs) represent a promising strategy to clear HIV-infected cells, but to date have not achieved clinical benefits. A likely hurdle is the limited T cell activation and persistence when HIV antigenemia is low, particularly during antiretroviral therapy (ART). To overcome this issue, we propose to use a cytomegalovirus (CMV) vaccine to stimulate CMV-specific T cells that express CARs directed against the HIV-1 envelope protein gp120. In this study, we use a GMP-compliant platform to engineer CMV-specific T cells to express a second-generation CAR derived from the N6 broadly neutralizing antibody, one of the broadest anti-gp120 neutralizing antibodies. These CMV-HIV CAR T cells exhibit dual effector functions upon in vitro stimulation through their endogenous CMV-specific T cell receptors or the introduced CARs. Using a humanized HIV mouse model, we show that CMV vaccination during ART accelerates CMV-HIV CAR T cell expansion in the peripheral blood and that higher numbers of CMV-HIV CAR T cells were associated with a better control of HIV viral load and fewer HIV antigen p24⁺ cells in the bone marrow upon ART interruption. Collectively, these data support the clinical development of CMV-HIV CAR T cells in combination with a CMV vaccine in HIV-infected individuals.

CTIM-29. CLINICAL EVALUATION OF CHLOROTOXIN-DIRECTED CAR T CELLS FOR PATIENTS WITH RECURRENT GLIOBLASTOMA

Chlorotoxin (CLTX), a peptide component of scorpion venom, exhibits selective and broad binding to glioblastoma (GBM) and other tumors with minimal activity against non-malignant cells. We have developed a novel CAR that utilizes CLTX as the tumor targeting domain. Preclinical studies established that CLTX-CAR T cells target GBM through recognition of a receptor complex incorporating membrane-bound matrix metalloprotease-2 (MMP-2). Here, we report initial clinical findings for our phase I trial evaluating safety and bioactivity of CLTX-CAR T cells in patients with MMP2+ recurrent GBM (NCT04214392). Weekly infusions of CLTX-CAR T cells are delivered locoregionally, either directly into the tumor cavity (ICT; Arm 1), or in combination with intracerebroventricular (ICV) delivery (dual ICT/ICV; Arm 2). At this interim analysis, four participants have received at least three cycles of CLTX-CAR T cells ICT (Arm 1; 3-8 cycles) at dose level 1 (DL1; 4M, 20M, 20M CAR T cells per cycle). None of the participants experienced dose limiting toxicity (DLT) during the DLT evaluation period of 28-days, although one participant experienced a serious adverse event of grade 3 cerebral edema, possibly attributed to CAR T cells. Overall, Arm 1-DL1 was well-tolerated, and the next patient cohort will be treated on Arm 2-DL1 (dual ICT/ICV; 8M, 40M, 40M CAR T cells per cycle), as per protocol design. Disease response was assessed by RANO, overall survival, and time to progression; three of four participants achieved a best response of stable disease. Liquid biopsy detected persistent CAR T cells in the tumor cavity throughout treatment, suggesting that the therapeutic cells are not immunogenic. Ongoing studies are evaluating biomarkers of response and resistance, including CAR T cell activation and inflammatory cytokines. This clinical study provides first-in-human evidence for the safety and feasibility of CLTX-CAR T cells as a new class of toxin-based CARs for treatment of GBM.

Phase II study of neratinib in older adults with HER2 amplified or HER2/3 mutated metastatic breast cancer

OBJECTIVE

The tolerability and efficacy of targeted therapy in older adults with cancer has not been adequately studied. Neratinib is a novel HER1, HER2, HER4 tyrosine kinase inhibitor that has recently been granted FDA approval for treatment of breast cancer. The major toxicity of neratinib is diarrhea, which affects up to 90% of patients. This phase II trial evaluates the safety and tolerability of neratinib in adults ≥60.

METHODS

Patients aged 60 or older with histologically proven metastatic breast cancer and HER2 amplification (defined by ASCO/CAP guideline) or HER2/HER3 activating mutation were enrolled to receive neratinib at 240 mg daily in 28-day cycles. The association between tolerability, defined as dose reduction and number of completed courses, and log2 Cancer and Aging Research Group (CARG) toxicity risk score was assessed using a Student's t-test and linear regression, respectively. Response rate, progression free survival, and overall survival were also evaluated.

RESULTS

25 patients were enrolled with median age of 66 (range 60-79). Seventy-six percent of patients were white, 16% Asian, and 8% African-American. Seventy-six percent were patients with hormone receptor (HR) positive metastatic breast cancer (MBC) and 24% were patients with HR negative MBC. Median number of prior lines of metastatic therapy were 3 (range 0-11). 20/25 (80%) had worst grade toxicities ≥2. A total of 9/25 (36%) had grade 3 toxicities including 5/20 (20%) diarrhea, 2/20 (8%) vomiting, and 2/20 (8%) abdominal pain. There were no grade 4 or 5 toxicities. A total of 9/25 (36%) had dose reduction, and 2/25 (8%) discontinued therapy due to toxicity. The association between dose reductions and CARG toxicity score reached borderline statistical significance suggesting a trend with participants with higher CARG toxicity risk scores being more likely to require a dose modification (p = 0.054). 1/25 (4%) had a partial response, 11/25 (44%) had stable disease, 12/25 (48%) had progression of disease, and 1/25 (4%) was not assessed. Median progression free survival (PFS) was 2.6 months (95% CI [2.56-5.26]), and median overall survival (OS) was 17.4 months (95% CI [10.3, NA]).

CONCLUSIONS

Neratinib was safe in this population of older adults with HER2 amplified or HER2/3 mutated metastatic breast cancer (BC). Higher CARG toxicity risk score may be associated with greater need for dose adjustments. Future studies are needed to confirm this finding.

Systemic Anti-PD-1 Immunotherapy Results in PD-1 Blockade on T Cells in the Cerebrospinal Fluid

Question

Are systemically administered programmed cell death 1–blocking antibodies able to penetrate and maintain bioactivity in the central nervous system?

Findings

In this case series study of 10 adult patients with high-grade gliomas, intravenous administration of pembrolizumab yielded cerebrospinal fluid (CSF) concentrations that were approximately 1% of that in serum but were sufficient for blocking programmed cell death 1 on T cells in the CSF.

Meaning

Systemically administered immune checkpoint blockade is able to reinvigorate T cells within the CSF compartment, supporting its bioavailability for treatment of tumors in the central nervous system and its use in combination with locoregionally delivered cellular therapies.

Importance

Little is known about the penetration and bioactivity of systemically administered programmed cell death 1 (PD-1) antibodies in the central nervous system. Such information is critical for advancing checkpoint antibody therapies for treatment of brain tumors.

Objective

To evaluate pembrolizumab concentrations and PD-1 blockade on T cells in the cerebrospinal fluid (CSF) after intravenous administration.

Design, Setting, and Participants

Cerebrospinal fluid and blood samples were collected from 10 adult patients with high-grade gliomas who were participating in clinical trials of intracranially administered chimeric antigen receptor (CAR) T cells and intravenous pembrolizumab at City of Hope in Duarte, California, from 2017 through 2019. Neuropharmacokinetic and immunologic correlative studies were performed on CSF and serum samples.

Interventions or Exposures

Pembrolizumab, 200 mg, was given intravenously every 3 weeks with a median of 2 cycles (range, 1-8). CAR T cells were administered intracranially every 1 to 4 weeks. Cerebrospinal fluid and blood samples were collected on the day of CAR T-cell administration and then 24 hours later for a total of 100 paired samples.

Main Outcomes and Measures

Pembrolizumab concentrations were measured by enzyme-linked immunosorbent assay, PD-1 blocking on T cells by flow cytometry, and results of PD-1 blockade on CAR T-cell function by in vitro tumor rechallenge assays.

Results

Of the 10 patients included in this study, the mean (SD) age was 45.7 (11.0) years, and 6 (60%) were women. Steady-state pembrolizumab concentrations in the CSF were achieved by 24 hours after initial intravenous administration, with a mean CSF:serum ratio of 0.009 (95% CI, 0.004-0.014). The CSF concentrations of pembrolizumab effectively blocked PD-1 on both endogenous T cells and intracranially administered CAR T cells in the CSF, with flow cytometric detection of surface PD-1 on the T cells decreasing from a mean (SD) of 39.3% (20.2%) before pembrolizumab to a mean (SD) of 3.8% (5.8%) 24 hours after pembrolizumab infusion. Steady-state concentrations in the CSF were maintained throughout the 21-day cycle of pembrolizumab, as was the PD-1 blocking effect, evidenced by no increase in detectable surface PD-1 on T cells in the CSF during that time period. Incubation of PD-1–expressing T cells with CSF samples from patients treated with pembrolizumab also resulted in PD-1 blockade.

Conclusions and Relevance

Results of this study demonstrate steady-state concentrations of pembrolizumab in CSF after intravenous administration as well as CSF concentrations that are sufficient for blocking PD-1 on endogenous and adoptively transferred T cells. This provides mechanistic insight regarding the ability of systemically administered PD-1 blocking antibodies to modulate T-cell activity in the brain.

Feasibility of intracerebrally administering multiple doses of genetically modified neural stem cells to locally produce chemotherapy in glioma patients

Neural stem cells (NSCs) are tumor tropic and can be genetically modified to produce anti-cancer therapies locally in the brain. In a prior first-in-human study we demonstrated that a single dose of intracerebrally administered allogeneic NSCs, which were retrovirally transduced to express cytosine deaminase (CD), tracked to glioma sites and converted oral 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU). The next step in the clinical development of this NSC-based anti-cancer strategy was to assess the feasibility of administering multiple intracerebral doses of CD-expressing NSCs (CD-NSCs) in patients with recurrent high grade gliomas. CD-NSCs were given every 2 weeks using an indwelling brain catheter, followed each time by a 7-day course of oral 5-FC (and leucovorin in the final patient cohort). Fifteen evaluable patients received a median of 4 (range 2–10) intracerebral CD-NSC doses; doses were escalated from 50 x 10⁶ to 150 x 10⁶ CD-NSCs. Neuropharmacokinetic data confirmed that CD-NSCs continuously produced 5-FU in the brain during the course of 5-FC. There were no clinical signs of immunogenicity, and only three patients developed anti-NSC antibodies. Our results suggest intracerebral administration of serial doses of CD-NSCs is safe and feasible and identified a recommended dose for phase II testing of 150 x 10⁶ CD-NSCs.

Regression of Glioblastoma after Chimeric Antigen Receptor T-Cell Therapy

A patient with recurrent multifocal glioblastoma received chimeric antigen receptor (CAR)-engineered T cells targeting the tumor-associated antigen interleukin-13 receptor alpha 2 (IL13Rα2). Multiple infusions of CAR T cells were administered over 220 days through two intracranial delivery routes - infusions into the resected tumor cavity followed by infusions into the ventricular system. Intracranial infusions of IL13Rα2-targeted CAR T cells were not associated with any toxic effects of grade 3 or higher. After CAR T-cell treatment, regression of all intracranial and spinal tumors was observed, along with corresponding increases in levels of cytokines and immune cells in the cerebrospinal fluid. This clinical response continued for 7.5 months after the initiation of CAR T-cell therapy. (Funded by Gateway for Cancer Research and others; ClinicalTrials.gov number, NCT02208362 .).

A phase I, pharmacokinetic, and pharmacodynamic evaluation of the DNA methyltransferase inhibitor 5-fluoro-2'-deoxycytidine, administered with tetrahydrouridine

PURPOSE

Inhibitors of DNA (cytosine-5)-methyltransferases (DNMT) are active antineoplastic agents. We conducted the first-in-human phase I trial of 5-fluoro-2'-deoxycytidine (FdCyd), a DNMT inhibitor stable in aqueous solution, in patients with advanced solid tumors. Objectives were to establish the safety, maximum tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of FdCyd + tetrahydrouridine (THU).

METHODS

FdCyd + THU were administered by 3 h IV infusion on days 1-5 every 3 weeks, or days 1-5 and 8-12 every 4 weeks. FdCyd was administered IV with a fixed 350 mg/m(2)/day dose of THU to inhibit deamination of FdCyd. Pharmacokinetics of FdCyd, downstream metabolites and THU were assessed by LC-MS/MS. RBC γ-globin expression was evaluated as a pharmacodynamics biomarker.

RESULTS

Patients were enrolled on the 3-week schedule at doses up to 80 mg/m(2)/day without dose-limiting toxicity (DLT) prior to transitioning to the 4-week schedule, which resulted in an MTD of 134 mg/m(2)/day; one of six patients had a first-cycle DLT (grade 3 colitis). FdCyd ≥40 mg/m(2)/day produced peak plasma concentrations >1 µM. Although there was inter-patient variability, γ-globin mRNA increased during the first two treatment cycles. One refractory breast cancer patient experienced a partial response (PR) of >90 % decrease in tumor size, lasting over a year.

CONCLUSIONS

The MTD was established at 134 mg/m(2) FdCyd + 350 mg/m(2) THU days 1-5 and 8-12 every 4 weeks. Based on toxicities observed over multiple cycles, good plasma exposures, and the sustained PR observed at 67 mg/m(2)/day, the phase II dose for our ongoing multi-histology trial is 100 mg/m(2)/day FdCyd with 350 mg/m(2)/day THU.

Age-related changes in nanoparticle albumin-bound paclitaxel pharmacokinetics and pharmacodynamics: influence of chronological versus functional age

PURPOSE

This study evaluated age-related changes in pharmacokinetic and pharmacodynamic parameters of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) in patients with metastatic breast cancer.

METHODS

Forty patients received nab-paclitaxel (100 mg/m(2) weekly for 3 weeks followed by a 1-week break) as first- or second-line chemotherapy. Blood samples were collected for analysis, and response was assessed every two cycles. Planned statistical analyses included linear regression to examine the relationship between age and pharmacokinetic variables (ln clearance [CL] and ln area under the curve [AUC]) and two-sided two-sample t tests to evaluate age differences in pharmacodynamic variables. The association between chemotherapy toxicity risk scores and pharmacokinetic and pharmacodynamic variables including grade ≥ 3 toxicity were examined post hoc.

RESULTS

Of 40 patients enrolled, 39 (98%) were evaluable (mean age: 60 years; range: 30-81 years). A partial response was achieved in 31%, and 38% had stable disease. There was a borderline positive association between age and 24-hour ln AUC (slope = 0.011; SE = 0.006; p = .055). Grade 3 toxicity was experienced by 26% (8% hematologic, 18% nonhematologic). There were no differences in age based on the presence of grade 3 toxicity (p = .75), dose reductions (p = .38), or dose omissions (p = .15). A significant association was noted between chemotherapy toxicity risk score category and presence of grade 3 toxicity (toxicity rate by risk score category: low, 5 of 30 patients; medium, 3 of 6 patients; high, 2 of 3 patients; p = .041).

CONCLUSION

A borderline significant relationship exists between age and 24-hour AUC, but no differences were noted for pharmacodynamic variables (grade 3 toxicity, dose reductions, or dose omissions) based on age. There is an association between toxicity risk score and grade ≥ 3 chemotherapy toxicity and pharmacokinetic variables. The treatment is well tolerated across all age groups.

Magnetic resonance imaging tracking of ferumoxytol-labeled human neural stem cells: studies leading to clinical use

Numerous stem cell-based therapies are currently under clinical investigation, including the use of neural stem cells (NSCs) as delivery vehicles to target therapeutic agents to invasive brain tumors. The ability to monitor the time course, migration, and distribution of stem cells following transplantation into patients would provide critical information for optimizing treatment regimens. No effective cell-tracking methodology has yet garnered clinical acceptance. A highly promising noninvasive method for monitoring NSCs and potentially other cell types in vivo involves preloading them with ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) to enable cell tracking using magnetic resonance imaging (MRI). We report here the preclinical studies that led to U.S. Food and Drug Administration approval for first-in-human investigational use of ferumoxytol to label NSCs prior to transplantation into brain tumor patients, followed by surveillance serial MRI. A combination of heparin, protamine sulfate, and ferumoxytol (HPF) was used to label the NSCs. HPF labeling did not affect cell viability, growth kinetics, or tumor tropism in vitro, and it enabled MRI visualization of NSC distribution within orthotopic glioma xenografts. MRI revealed dynamic in vivo NSC distribution at multiple time points following intracerebral or intravenous injection into glioma-bearing mice that correlated with histological analysis. Preclinical safety/toxicity studies of intracerebrally administered HPF-labeled NSCs in mice were also performed, and they showed no significant clinical or behavioral changes, no neuronal or systemic toxicities, and no abnormal accumulation of iron in the liver or spleen. These studies support the clinical use of ferumoxytol labeling of cells for post-transplant MRI visualization and tracking.

Neural stem cell-mediated CE/CPT-11 enzyme/prodrug therapy in transgenic mouse model of intracerebellar medulloblastoma

Medulloblastoma is a heterogeneous diffuse neoplasm that can be highly disseminated, and is the most common malignant childhood brain tumor. Although multimodal treatments have improved survival rates for patients with medulloblastoma, these tumors are associated with high morbidity and mortality. New treatment strategies are urgently needed to improve cure rates and, importantly, to spare normal brain tissue from neurotoxicity and patients from life-long cognitive and functional deficits associated with current therapies. In numerous preclinical brain tumor models, neural stem cells (NSCs) have shown great promise as delivery vehicles for therapeutic genes. Here, we have used an established, genetically modified human NSC line (HB1.F3.CD) to deliver carboxylesterase (CE) to cerebellar tumor foci and locally activate the prodrug CPT-11 (Irinotecan) to the potent topoisomerase I inhibitor SN-38. HB1.F3.CD NSC tumor tropism, intratumoral distribution and therapeutic efficacy were investigated in clinically relevant experimental models. Magnetic resonance imaging was used for in vivo tracking of iron nanoparticle-labeled NSCs, and to assess the therapeutic efficacy of CE-expressing HB1.F3.CD cells. As compared to controls, a significant decrease in tumor growth rate was seen in mice that received both NSCs and CPT-11 as their treatment regimen. Thus, this study provides proof-of-concept for NSC-mediated CE/CPT-11 treatment of medulloblastoma, and serves as a foundation for further studies toward potential clinical application.

Toxicity equivalence range design (TEQR): a practical Phase I design

PURPOSE

This paper introduces the target equivalence range (TEQR) design, a frequentist implementation of the modified toxicity probability interval (mTPI) design, as a competitor to the standard 3+3 design (3+3). The 3+3 is the work horse design in Phase I. It is good at determining if a safe dose exits, but provides poor accuracy and precision in estimating the level of toxicity at the maximum tolerated dose (MTD). Its main competitor, the continual reassessment method (CRM) has not found a true niche in the Phase I armamentarium resulting from statistical and implementation complexities.

METHODS

We describe the four competing designs (3+3, mTPI, CRM, and TEQR), comparing them based on i) operating characteristics from simulated trials, and ii) ease of implementation.

RESULTS

The TEQR is better than the 3+3 when compared on; 1) number of times the dose at or nearest the target toxicity level was selected as the MTD, 2) number of patients assigned to dose levels at or nearest the MTD, 3) overall trial dose limiting toxicity rate and 4) accuracy and precision of estimates for the rate of toxicity at the MTD. Further it is reasonably comparable to the CRM and mTPI on 1-3.

CONCLUSION

The TEQR offers trial designers a competitor to the 3+3 for ease of implementation with better operating characteristics and the added attraction of a glimpse of activity at the MTD. The R package TEQR, freely available from the comprehensive R archive network, includes functions to calculate dose escalation guidelines and operating characteristics.

The 3'-flap pocket of human flap endonuclease 1 is critical for substrate binding and catalysis

Flap endonuclease 1 (FEN1) proteins, which are present in all kingdoms of life, catalyze the sequence-independent hydrolysis of the bifurcated nucleic acid intermediates formed during DNA replication and repair. How FEN1s have evolved to preferentially cleave flap structures is of great interest especially in light of studies wherein mice carrying a catalytically deficient FEN1 were predisposed to cancer. Structural studies of FEN1s from phage to human have shown that, although they share similar folds, the FEN1s of higher organisms contain a 3'-extrahelical nucleotide (3'-flap) binding pocket. When presented with 5'-flap substrates having a 3'-flap, archaeal and eukaryotic FEN1s display enhanced reaction rates and cleavage site specificity. To investigate the role of this interaction, a kinetic study of human FEN1 (hFEN1) employing well defined DNA substrates was conducted. The presence of a 3'-flap on substrates reduced Km and increased multiple- and single turnover rates of endonucleolytic hydrolysis at near physiological salt concentrations. Exonucleolytic and fork-gap-endonucleolytic reactions were also stimulated by the presence of a 3'-flap, and the absence of a 3'-flap from a 5'-flap substrate was more detrimental to hFEN1 activity than removal of the 5'-flap or introduction of a hairpin into the 5'-flap structure. hFEN1 reactions were predominantly rate-limited by product release regardless of the presence or absence of a 3'-flap. Furthermore, the identity of the stable enzyme product species was deduced from inhibition studies to be the 5'-phosphorylated product. Together the results indicate that the presence of a 3'-flap is the critical feature for efficient hFEN1 substrate recognition and catalysis.

Effect of xylose on the synthesis of phosphorylcholine and phosphorylethanolamine in rat lenses

Choline, an essential phospholipid precursor, enters the lens by a facilitated transport system and is phosphorylated to form phosphorylcholine (P-choline). Intact lenses incubated with [3H]choline accumulate both [3H]choline and P-[3H]choline. The rate and extent of this accumulation have been used to study the effects of osmotic or oxidative cataractogenic stress, and also to test the ability of compounds to protect lenses from stress-related damage. The initial effect of oxidative stress on choline metabolism is decreased choline transport, but the mechanism by which osmotic stress affects the accumulation of [3H]choline is not understood. The effects of osmotic and oxidative stress on choline influx and metabolism were compared in rat lenses incubated in TC-199 medium. After osmotic stress by incubation with 30 mM xylose for up to 24 hr, lenses accumulated the same amount of radiolabel as controls during a 30 min pulse with [3H]choline. However, if the lenses were exposed to [3H]choline for 6 hr so that accumulation of radiolabel in the lenses was limited by the rate of P-choline synthesis, xylose treated lenses accumulated less choline than controls. Separation of the lenticular radiolabel into [3H]choline and P-[3H]choline confirmed that xylose decreased synthesis of P-choline, although adequate unphosphorylated [3H]choline was available in the lenses. A decrease in P-[3H]ethanolamine synthesis was also seen in xylose-treated lenses incubated with [3H]ethanolamine. Ethanolamine can enter lenses by a non-saturable process which is not dependent upon a transporter. Although xylose decreased P-choline synthesis in intact lenses, neither xylose nor xylitol inhibited choline kinase in lens homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Lower vertebral bone density in male long distance runners

Bone density in 13 male long distance runners (28.7 +/- 1.2 yr, 67.6 +/- 2.0 kg) and 11 male nonrunners (26.8 +/- 1.3 yr, 71.0 +/- 2.2 kg) was compared. Bone was measured at the lumbar spine and mid-tibia using dual photon absorptiometry and at the mid-radius using single photon absorptiometry. Runners (mean weekly training 92.2 +/- 6.3 km) had significantly lower (P less than 0.05) vertebral bone mineral density (1.12 +/- 0.03 g.cm-2) than nonrunners (1.24 +/- 0.04 g.cm-2). Tibial and radial bone mineral density did not differ between the groups. Daily calcium intake for runners (1,373 +/- 486 mg) and nonrunners (1,267 +/- 236 mg) exceeded the RDA. The results of this study suggest that long distance running may lead to decreased vertebral bone mineral density. The hormonal changes that occur with endurance training may contribute to this decrease.

Effects of a Rebound Exercise Training Program on Aerobic Capacity and Body Composition

In brief: Training on rebound exercise equipment (minitrampolines) is a popular new approach to aerobic conditioning, but its physiological benefits have been a matter of debate. This study was designed to determine if rebound aerobic dancing is an effective way to improve aerobic capacity and body composition. A group of previously sedentary college women who trained on rebound equipment three times a week for eight weeks showed a 9% increase in max but no significant change in percent body fat. A control group showed no significant changes. The improvement was similar to results produced by conventional aerobic dance programs of like intensity but moderate in comparison to other established forms of aerobic exercise.