Changes in Physical Activity, Functional Capacity, and Cardiac Function during Breast Cancer Therapy

PURPOSE

Functional capacity and cardiac function can decline during breast cancer (BC) therapy. In non-cancer populations, higher physical activity (PA) is associated with better physical function and cardiac health. This study compared baseline PA, functional capacity, and cardiac function between women with and without BC and tested if greater PA participation was related to higher functional capacity and/or better heart function after three months of BC therapy.

METHODS

Data was collected in 104 women without BC (82% Caucasian, baseline only) and 110 women with stage I-III BC (82% Caucasian) before therapy and after three months of treatment. Participants self-reported PA and underwent six-minute walk distance (6MWD) testing to measure functional capacity and cardiovascular magnetic resonance to assess left ventricular ejection fraction (LVEF). Analyses were adjusted for age, race, body mass index (BMI), and medication use.

RESULTS

The BC group was older (56.2 ± 10.7 vs 52.1 ± 14.7 yrs, P=0.02) with a higher average BMI than the non-cancer group (30.3 ± 6.8 vs 27.7 ± 6.2 kg/m2, P<0.01). Pre-treatment, BC participants reported lower PA scores (27.9 ± 2.8 vs 34.9 ± 2.8, P=0.04) with similar 6MWD and LVEF relative to those without cancer (485 ± 11 vs 496 ± 11 m, P=0.4 and 59.7 ± 0.7 vs 58.9 ± 0.8%, P=0.37, respectively). After three months of BC therapy, declines were observed for PA scores (27.9 ± 2.8 vs 18.3 ± 2.5, P=0.02), 6MWD (485 ± 11 vs 428 ± 10 m, P<0.001), and LVEF (59.7 ± 0.7 vs 56.1 ± 0.7%, P<0.001). Compared to BC participants who reported no PA at three months (n=24, 22%), BC women who reported any PA (n=78, 86%) had higher 6MWD (442 ± 11 vs 389 ± 17 m, P=0.006) but similar LVEF (56.5 ± 0.9 vs 55.3 ± 1.5%, p=0.5). Women who reported any PA were less likely to exhibit an LVEF below normal (<50%) or decline in LVEF of 'â•10 points compared to inactive women (BMI-adjusted, OR [95% CI]: 0.27 [0.09, 0.85]).

CONCLUSIONS

These preliminary results indicate that self-reported PA, LVEF and 6MWD decline in the first three months of BC treatment, but PA participation during BC treatment may mitigate declines in functional capacity and cardiac function. Further research is needed to identify barriers and facilitators of PA participation during BC therapy.

FUNDING

Data collection was funded by the Wake Forest NCORP Research Base grant 2UG1CA189824 with support of the NCI Community Oncology Research Program (NCORP). Additional funding for this study was provided by grants from the National Institutes of Health, National Cancer Institute (1R01CA199167 and 5T32CA093423).

CLINICAL TRIAL ID

NCT02791581 for WF97415 UPBEAT.

Does MR perfusion imaging impact management decisions for patients with brain tumors? A prospective study

BACKGROUND AND PURPOSE

MR perfusion imaging can be used to help predict glial tumor grade and disease progression. Our purpose was to evaluate whether perfusion imaging has a diagnostic or therapeutic impact on clinical management planning in patients with glioma.

MATERIALS AND METHODS

Standard MR imaging protocols were interpreted by a group of 3 NRs in consensus, with each case being interpreted twice: first, including routine sequences; and second, with the addition of perfusion imaging. A multidisciplinary team of treating physicians assessed tumor status and created hypothetical management plans, on the basis of clinical presentation and routine MR imaging and then routine MR imaging plus perfusion MR imaging. Physicians' confidence in the tumor status assessment and management plan was measured by using Likert-type items.

RESULTS

Fifty-nine consecutive subjects with glial tumors were evaluated; 50 had known pathologic diagnoses. NRs and the treatment team agreed on tumor status in 45/50 cases (κ = 0.81). With the addition of perfusion, confidence in status assessment increased in 20 (40%) for NRs and in 28 (56%) for the treatment team. Of the 59 patient-care episodes, the addition of perfusion was associated with a change in management plan in 5 (8.5%) and an increase in the treatment team's confidence in their management plan in 34 (57.6%). NRs and the treatment team found perfusion useful in most episodes of care and wanted perfusion included in future MR images for >80% of these subjects.

CONCLUSIONS

Perfusion imaging appears to have a significant impact on clinical decision-making and subspecialist physicians' confidence in management plans for patients with brain tumor.

A phase II study of chemoradiation followed by adjuvant temozolomide and poly-ICLC in patients with newly diagnosed glioblastoma: 12- and 18-month survival data (NABTT 0501)

2002

Background: Polyinosinic-polycytidylic (poly-ICLC), is a double-stranded RNA that stimulates a variety of host defense mechanisms including T-cell and natural killer cell activation, cytokine release and specific anti-proliferative and anti-viral effects. The objective of this study was to determine the safety and efficacy of poly-ICLC when added to adjuvant treatment for newly diagnosed glioblastoma. Methods: Newly diagnosed patients > 18 years with histologically proven glioblastoma received standard external beam radiation with concurrent low-dose temozolomide (TMZ) (75 mg/m2) followed by adjuvant cycles of TMZ for 5 days (150–200 mg/m2) (week 1) then intramuscular injections of poly-ICLC (20 mcg/kg) 3 times a week (weeks 2–8; total 21 injections) with week 9 off and no limit to the number of adjuvant cycles (TMZ + poly-ICLC). Imaging evaluations were performed before every cycle. Results: There were 97 patients enrolled (60 men); median age 56 yrs (range 21–85); median KPS 90 (range 60–100). Fourteen patients did not start adjuvant treatment (5 patient request and 4 investigator withdrawal; 2 progressive disease; 1 death; 1 toxicity; 1 other). The most frequent CTC grade 3–4 toxicities occurring in > 5% of subjects at least possibly related to poly-ICLC were leukopenia (20%), thrombocytopenia (14%), anemia (13%), neutropenia (10%), and SGPT (9%) or alkaline phosphatase (7%) elevation. Two deaths during adjuvant treatment were considered unlikely related to poly-ICLC. To date 71 of 97 patients have survived at least 12 months from diagnosis. The estimated median survival for the entire cohort was 17.2 months (95% CI: 15.5–19.3 months). Overall survival for the cohort at 12 months was 73.2% (95% CI: 63%-82%) and at 18 months 47.4% (95% CI: 37–58%). For only those subjects 18–70 years, overall survival at 18 months was 51.8% (95% CI: 41–63%). This is contrasted with EORTC 26981/22981 that reported an 18 month overall survival of 39.4% (95% CI: 33.8–45.1). Conclusions: The addition of poly-ICLC to a modified adjuvant treatment regimen for newly diagnosed GB is well-tolerated. Survival data at 12 and 18 months suggest increased efficacy compared to chemoradiation with adjuvant TMZ only.

[Table: see text]

Feasibility and phase I trial of tandutinib in patients with recurrent glioblastoma

2039

Background: Platelet-derived growth factor signaling is important in gliomagenesis and PDGFR-β is expressed on >90% of endothelial cells in glioblastoma specimens. Methods: We report the results of a feasibility and phase I study of tandutinib (MLN518), an orally bioavailable, quinazoline-based inhibitor of type III receptor tyrosine kinases including PDGFR-β, FLT-3, and c-Kit, in patients with recurrent glioblastoma (GBM) conducted in the New Approaches to Brain Tumor Therapy (NABTT) consortium. Results: A feasibility study was conducted in 6 recurrent GBM patients in whom resection was clinically indicated. These patients received tandutinib 500-mg BID for 7 days prior to resection. In these patients, the drug was measured in tumor tissue and plasma samples obtained shortly before and after the resection by LC/MS. The mean ± SD concentration of tandutinib in tumor tissue was 7.2 ± 3.2 μg/mL and the mean ratio of its concentration in brain tumor-to-plasma was 9.6 ± 7.7. A phase I study was conducted in 19 patients to determine the MTD in this recurrent GBM population with sequential assessment of the following dose levels: 500-, 600-, and 700-mg BID. Four patients were replaced due to early withdrawal unrelated to toxicity. Dose limiting toxicities were observed in 1/6 patients at 500-mg BID (grade 3 phosphorous, grade 3 fatigue, grade 3 somnolence in 1 patient); 1/6 patients at 600-mg BID (grade 3 phosphorous); 2/3 patients at 700-mg BID (grade 3 fatigue, grade 3 weakness). 600-mg BID was declared the MTD and a phase II study has been initiated at this dose level. Conclusions: The mean brain tumor tissue-to-plasma ratio of tandutinib in GBM patients receiving 500-mg BID exceeded the estimated threshold ratio of 0.33 that was considered as being necessary to achieve local cytotoxic concentrations in brain tumors. The MTD of tandutinib in the recurrent GBM population is 600-mg BID. A phase II trial has been initiated at this dose level.

[Table: see text]

NABTT-0702: A phase II study of R-(-)-gossypol (AT-101) in recurrent glioblastoma multiforme (GBM)

2010

Background: R-(-)-gossypol (AT-101) is an oral bcl-2 family protein inhibitor (Bcl-2, Bcl-XL, Mcl-1, Bcl-W) and potent inducer of proapoptotic proteins. A prior study of racemic gossypol demonstrated objective responses in patients with malignant glioma. The objectives of this trial were to determine the efficacy and safety of the more active (-) enantiomer of gossypol (AT-101) in patients with recurrent GBM. Methods: Fifty-six patients with recurrent GBM were enrolled in this multi-institution phase II clinical trial through the NABTT CNS consortium designed to detect a 33% increase in overall survival (OS, primary endpoint) from 5 to 6.65 months with Power/Alpha 80%/0.01. All patients had received prior radiation and none had received more than two prior treatments. Patients taking P450-inducing anticonvulsants were not eligible. AT-101 was administered at 20 mg PO per day for 21 of 28 days in repeated cycles. Radiographic assessment of tumor response was made at q 8-week intervals. Results: Fifty-six patients were enrolled with a median age of 59 (range 34–79) and KPS of 80 (range 60–100). Grade 3 or greater adverse events possibly or probably related to AT-101 included fatigue (n = 2), ileus (n = 1), elevated cardiac troponin T levels (n = 1), elevated GGT (n = 1), and thrombocytopenia (n = 1). Response data is available for 43 patients. OS determination is ongoing. Seven patients (16%) had stable disease as the best response. One partial response (centrally reviewed) was observed. No complete responses were observed. Although treatment is ongoing, two patients are without progression after more than 7 months of therapy. Conclusions: AT-101 is well tolerated and without unique toxicities in patients with recurrent GBM. Further follow-up will determine the impact of AT-101 on OS and whether any tissue correlate is predictive of efficacy.

No significant financial relationships to disclose.

Angiotensin-(1–7), a small molecule inhibitor of glioblastoma growth

2024

Background: Recent studies suggest that anti-angiogenic therapies may be effective in patients with glioblastoma multiforme (GBM), a highly vascular tumor. We have previously demonstrated that angiotensin-(1–7) [Ang-(1–7)], an endogenous heptapeptide with anti-angiogenic properties, significantly reduced the serum-stimulated growth of three human glioblastoma cell lines which contained mRNA for the AT(1–7) receptor mas. We now provide the first evidence that Ang-(1–7) markedly decreases the proliferation and growth of human glioblastomas in vivo using a xenograft model. Methods: Athymic mice with tumors resulting from injection of human U87 glioblastoma cells were treated for 18 days with saline or 1000 μg/kg Ang-(1–7), delivered by subcutaneous injection every 12 h. Results: The average volume of the tumors from mice treated with the heptapeptide was approximately 3-fold less than the size of the tumors from control animals (586.1 ± 94.5 mm3 vs 1845.5 ± 238.1 mm3; n = 6, p < 0.05). Further, the tumors from mice injected with Ang-(1–7) weighed almost 50% less than the tumors from mice treated with saline (1.31 ± 0.12 g vs. 2.45 ± 0.23 g; n = 6, p < 0.05). The Ang-(1–7)-mediated reduction in tumor growth was associated with a significant decrease in immunoreactive Ki67, a proliferation marker. In addition, a marked down-regulation of cyclooxygenase 2 (COX-2), prostaglandin E synthase (PGES-1) and vascular endothelial growth factor (VEGF) was observed in tumors from Ang-(1–7)-injected mice compared to saline-treated controls (COX-2: 1.00 ± 0.06 vs 0.55 ± 0.07 relative gene expression; PGES-1: 1.03 ± 0.08 vs. 0.40 ± 0.06; VEGF: 1.05 ± 0.07 vs. 0.59 ± 0.09; n = 6, p < 0.05) with no effect on COX-1 or PGI synthase mRNA. Conclusions: These results suggest that Ang-(1–7) may reduce the concentration and ratio of proliferative and anti-proliferative prostaglandins to decrease glioblastoma growth as well as attenuate angiogenesis through a reduction in VEGF. Thus, Ang-(1–7) may be a new, first-in-class small molecule inhibitor for the treatment of glioblastoma, providing combination therapy as a selective COX-2/PGES-1 and angiogenic inhibitor, targeting a specific AT(1–7) receptor mas.

No significant financial relationships to disclose.

A phase II trial of thalidomide (Thal) and procarbazine (Pro) in adults with recurrent or progressive malignant gliomas (MG)

2067

Background: Thal and Pro are among the few agents with demonstrated activity against MG. A two-stage, phase II trial was initiated within the WFURB to establish the response rate of combination Thal-Pro in patients (pts) with recurrent or progressive MG. Methods: Eligibility included pt age = 18 with measurable tumor on contrast enhanced brain scans; KPS = 60; normal liver, kidney and hematologic function; and treatment with = 2 prior regimens. Pts were required to participate in the S.T.E.P.S. Program and mandated to comply with agreed upon measures to avoid conception. Protocol therapy included Pro 250mg/m2/d x 5d q 28days and Thal 200mg/day continuously. Intrapatient dose escalation of Thal was attempted (increase by 100mg/day weekly as tolerated) to a maximum of 800mg/day. All pts received daily pyridoxine(100mg), warfarin(1mg) and stool softeners/laxatives. MRI/CT scans were performed prior to each odd cycle (every 8 weeks) to assess response based upon changes in the products of the largest bidimensional tumor diameters. Quality of life questionnaires including the FACT-Br were performed at baseline and prior to each odd cycle in all treated pts. Results: 18 pts (11 male) were enrolled (median age 50, range 27–63). One pt refused any therapy and is excluded from the analysis. The 17 treated pts received 36 cycles (median 2) of therapy. The median maximum Thal dose achieved was 400mg (range 200–800). No complete or partial responses were seen; 1 pt (6%) experienced stable disease, 14 (82%) progressed as best response and 2 (12%) were not evaluable for response. Median time to progression was 2.1 months (95% CI, 1.5–2.5). 14 pts have died; median survival was 7.6 months (95% CI, 3.5–9.4). Grade 3/4 drug related toxicity was minimal. Conclusions: Despite modest individual response rates in multiple prior phase II and III trials, the combination of Pro and Thal demonstrated no efficacy in this trial and this combination is unworthy of further investigation in pts with MG. Supported by NCI 1 U10 CA81851 and Celgene.

No significant financial relationships to disclose.

A Phase III randomized study comparing the effects of oxandrolone (Ox) and megestrol acetate (Meg) on weight (wt), lean body mass (LBM) and quality of life (QOL) in solid tumor patients (pts) receiving chemotherapy (chemo)

18546

Background: Involuntary wt loss is a significant problem in pts with cancer and may lead to a decline in QOL, limit treatment options and reduce survival. Wt loss in these pts disproportionately represents a loss of muscle mass. Meg, a synthetic progesterone derivative, promotes wt gain mostly through an increase in adipose tissue rather than in LBM. Ox is a potent oral anabolic steroid with minimal androgenic activity which promotes wt gain primarily through increased LBM. Methods: Prospective, randomized phase III trial comparing the effects of Ox and Meg on wt, body composition and QOL in pts with solid tumors and wt loss receiving chemo. Body composition was serially assessed by Bioelectrical Impedance Analysis. QOL was evaluated with the FACT-G and the Anorexia/Cachexia subscale (FAACT). Eligibility: age ≥18; PS: 0–2; life expectancy ≥6 mos; near normal organ function; and progressive wt loss on chemo. Ineligibility: full dose anticoagulation; hormonally responsive or hematologic malignancies; and ongoing or planned treatment with corticosteroids (antiemetic use allowed), estrogens or progestins. The primary endpoint was LBM after 12 wks of drug therapy. Study design allowed 90% power for detecting a 1.5 kg difference between treatment groups using a 5% two-sided level of significance. A max of 155 pts were to be accrued. An interim analysis was planned after 62 pts had completed 12 wks on study. Results: As of 12/05, 74 pts have been accrued (72 eligible): median age 64 yrs, 42% females and 62% stage 4 disease. 25 pts (arm 1:8, arm 2:17) have completed 12 wks of therapy and 20 remain on study. 76 Grade 3/4 toxicities (arm 1:23, arm 2:53) and 1 grade 5 arrhythmia (arm 2) have been recorded. Accrual is ongoing and differing trends in wt gain and body composition between arms are emerging. Conclusions: This is the first and only trial comparing these two commonly utilized therapies for cancer-related anorexia/cachexia. Differences in efficacy, particularly effects on LBM, QOL and toxicity which emerge from this trial are likely to influence symptom management standards of care in the oncology community. Supported by Savient Pharmaceuticals and NCI grant 1 U10 CA81851.

No significant financial relationships to disclose.

Phase I study of twice-weekly gemcitabine and concurrent thoracic radiation for patients with locally advanced non-small-cell lung cancer

PURPOSE

To determine the maximum tolerated dose (MTD) and dose-limiting toxicity of twice-weekly gemcitabine and concurrent thoracic radiation in patients with Stage IIIa/IIIb non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

Seventeen patients with histologically confirmed Stage IIIa and IIIb NSCLC were studied. Gemcitabine was administered via a 30-min i.v. infusion twice weekly for 6 weeks concurrent with 60 Gy of thoracic radiation. Gemcitabine, starting at a twice-weekly dose of 10 mg/m2 (20 mg/m2/week), was escalated in 10-15 mg/m2 increments in successive cohorts of 3 to 6 patients until dose-limiting toxicity was observed.

RESULTS

Of the 17 patients entered, 16 were evaluable for toxicity. The dose-limiting toxicity at 50 mg/m2 given twice weekly (100 mg/m2/week) was Grade 3 pneumonitis observed in 1 patient, Grade 3 pulmonary fibrosis in a second patient, and Grade 4 esophagitis observed in two additional patients. Twice-weekly gemcitabine at a dose of 35 mg/m2 was determined to be the MTD. The overall response rate for the 16 evaluable patients was 88%. The median survival for the entire group is 16.0 months.

CONCLUSIONS

The MTD of twice-weekly gemcitabine is 35 mg/m2 (70 mg/m2/week) given with thoracic radiation. A Phase II study within the Cancer and Leukemia Group B to ascertain the potential efficacy of this treatment regimen is in development.

Chemotherapy of low-grade gliomas

Histologic subtypes of low-grade gliomas include pilocytic astrocytomas (World Health Organization [WHO] grade I), diffuse infiltrating astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas (WHO grade II). Although extended survival is typical with these tumors, most patients eventually succumb to recurrent or progressive disease despite receiving either adjuvant radiation therapy or radiation at the time of recurrence. Not surprisingly, chemotherapy for low-grade gliomas has primarily been evaluated in the salvage setting of postradiotherapy progression in both adults and children. Unfortunately, the published body of literature describing chemotherapy for these tumors is small and subject to a number of confounding methodologic limitations. Nonetheless, some guidelines for the use of chemotherapy in these patients can be inferred from the published experience. The data reviewed clearly identifies a potential benefit for PCV chemotherapy (procarbazine, CCNU, and vincristine) in at least a subset of patients with low-grade oligodendroglial tumors. Nitrosoureas and platinum agents appear to have modest efficacy in recurrent oligodendroglial tumors and in some patients with newly diagnosed or progressive low-grade astrocytomas; however, surgery and radiation remain the primary treatment modalities for this group of malignancies. Until new data becomes available, chemotherapy still should be used only as a salvage option in previously irradiated patients with recurrent or progressive low-grade gliomas.

Utility of decompressive surgery in the prophylaxis and treatment of cisplatin neuropathy in adult rats

Cisplatin produces a dose-dependent and dose-limiting peripheral neuropathy in patients. This study tested the hypothesis that this clinical neuropathy results from the chronic compression of peripheral nerves rendered susceptible to injury because of cisplatin-induced microtubular dysfunction. A quantitative model of cisplatin neurotoxicity was developed by administering cisplatin to rats and measuring the neuropathy by hindlimb walking track assay. The study aims were: (1) to characterize neuropathy induced by cisplatin in the adult rat; (2) to evaluate the role of decompressive surgery in the prevention of cisplatin neuropathy; and (3) to determine whether decompressive surgery was an effective treatment for established neuropathy. The assay demonstrated an increased print length in animals after 8 weeks of cisplatin (p < 0.01). This neuropathy progressed for 6 weeks after cisplatin was stopped, and reversed slowly over 3 months. These abnormalities were prevented by early tarsal tunnel decompression. Decompressive surgery was also beneficial, if performed early in the course of the neuropathy; abnormalities reversed in 5 weeks and remained normal for the remainder of the study. Control animals had progressive abnormalities which slowly resolved over a period of 18 weeks after discontinuing cisplatin. However, decompressive surgery performed after the neuropathy was established did not alter the neuropathic walking-track pattern. These studies provide insight into the etiology and possible therapeutic approaches to cisplatin neuropathy. Although further studies are required, they suggest that, in selected patients, decompressive surgery may have a role in the prevention or early treatment of cisplatin-induced neuropathy. Patients with underlying clinical or subclinical compressive neuropathies could be at high risk for the development of cisplatin neuropathy, and quantitative monitoring of neuropathies may be useful.

Chemotherapy of cerebral metastases from solid tumors

With proper staging, patients with parenchymal brain metastases from solid tumors are usually found to have widespread extracranial disease. Systemic chemotherapy offers the potential advantage of simultaneous therapy of both intracranial and extracranial tumor. Limited data is available on the efficacy of drug therapy alone in this patient population for selected patients with chemosensitive malignancies and brain metastases, systemic chemotherapy administration represents a useful treatment modality when given at presentation or following recurrence after surgery or radiation therapy.

In vitro and in vivo studies of subcutaneous hydromorphone implants designed for the treatment of cancer pain

Unrelieved cancer pain remains a significant problem worldwide. Patients receive inadequate analgesia for a variety of complex and multifactorial reasons. Limited availability of opioids secondary to concerns about potential diversion of these medications for illicit use and poor compliance with oral regimens are significant factors in many countries. This study was designed to develop and test an implantable opioid delivery device capable of releasing a potent opioid subcutaneously at a continuous rate for 4 weeks. A low temperature solvent casting technique was used to formulate ethylene vinyl acetate (EVA) copolymer disks containing 50% hydromorphone by weight. The release characteristics of disks of different height and diameter, coated and uncoated, and with and without a central uncoated channel were studied. The effect of temperature and pH were also evaluated. In vitro assessments were conducted in phosphate buffer using UV spectrophotometry. In vivo studies employed New Zealand White Rabbits and a radioimmunoassay. Plasma levels following hydromorphone delivery by polymer, osmotic pump, and intravenous administration were compared. In vitro, uncoated EVA polymer disks measuring 1.05 cm in diameter and 0.27 cm in height released an initial large burst of hydromorphone. Coating the disks with 100-200 microM of poly(methyl-methacrylate) prevented drug egress from the polymer. A central uncoated channel measuring 1.25 mm in diameter in an otherwise coated polymer virtually eliminated the initial burst of drug release and provided near zero-order hydromorphone release at an average rate of 164 micrograms per hour for 4 weeks. Doubling the height of the polymer approximately doubled the release rate while doubling the diameter of the polymer extended the duration of drug release to over 8 weeks. In rabbits, stable plasma hydromorphone concentrations (23-37 ng/ml) were sustained for 4 weeks following implantation of 2 polymers with an uncoated central channel. No initial burst of hydromorphone release was noted. Increasing the number of polymers produced sustained and predictable increases in plasma hydromorphone concentrations. Plasma levels were similar with subcutaneous hydromorphone delivered by polymer and osmotic pump and much less variable than with intravenous bolus hydromorphone. A uniquely configured implantable drug delivery device has been developed using materials which are approved for human use. It safely and reproducibly releases hydromorphone for weeks in vitro and in vivo without an initial burst of drug release. Varying the thickness, diameter, and number of implants provides flexibility in the release rate and duration of release. This implantable opioid delivery device could provide a sustained subcutaneous infusion of hydromorphone to patient with cancer pain in developed and developing nations without pumps, catheters, or extensive outpatient support services. In addition, it should improve compliance and reduce concern regarding illicit diversion of opioids.

Tissue and tumor distribution of C-penclomedine in rats

Penclomedine, a lipophilic alpha-picoline derivative, is undergoing clinical development presently because of its pronounced antitumor activity against intracerebral (i.c.) tumor xenografts. Penclomedine may be metabolized in vivo to a more potent compound. Although it may be useful in the treatment of brain tumors, the drug has caused significant neurotoxicity in early clinical trials. The possibility that antitumor activity and neurotoxicity may be mediated by different mechanisms prompted a study assessing the differential distribution of penclomedine and penclomedine metabolites to brain and i.c.-implanted tumors in rats. In the present study, quantitative autoradiographic analysis demonstrated a homogenous distribution of 14C-penclomedine in all organs within 1 h of administration. Levels of 14C-penclomedine in both i.c. and s.c. tumors were three times higher than in normal brain tissue. High-performance liquid chromatography combined with gas chromatography and mass spectrophotometry demonstrated that two metabolites, O-demethyl penclomedine and penclomic acid, were responsible for most of the plasma radioactivity. Penclomic acid was also the most common urinary metabolite of penclomedine. In liver samples, although a large number of metabolite peaks were detected, no parent compound could be identified. However, in tumors and all other tissues, penclomedine was the main compound detected. The finding of penclomedine in normal brain tissue indicates not only that this drug may be useful in tumors with normal blood-brain barrier function, but also that it may be directly neurotoxic.

The distribution of systemically administered [3H]-paclitaxel in rats: a quantitative autoradiographic study

Paclitaxel is an important agent in the treatment of many common malignancies. Although the symptomatic peripheral neuropathy caused by this drug is its principal nonhematologic toxicity, little is known about the distribution of paclitaxel within the peripheral or central nervous system following systemic administration. In order to study paclitaxel's distribution in neural and extraneural tissues, adult Sprague-Dawley rats were sacrificed 2 h after a tail vein injection of [3H]-paclitaxel (0.03 mg/kg, 250 microC/rat). Samples of lung, heart, liver, spleen, kidney, skeletal muscle, brain, spinal cord, dorsal root ganglion, and peripheral nerve were then removed and snap-frozen. These tissues were sectioned at 10 microns in a cryostat and exposed to autoradiography film for 2 weeks. The distribution and concentrations of [3H]-paclitaxel in plasma, urine and cerebrospinal fluid were also determined using liquid scintillation spectrometry. [3H]-paclitaxel concentrations (and organ/plasma concentration ratios) in plasma, urine and cerebrospinal fluid were 2.6 nM (1), 38 nM (15) and 0.7 nM (0.3), respectively. A relatively homogeneous distribution of [3H]-paclitaxel was observed in liver [412 nM (151)], spleen [351 nM (133)], heart [319 nM (117)], lung [268 nM (93)] and muscle [69 nM (26)]. Higher concentrations of [3H]-paclitaxel were noted in the portal triads [869 nM (361)], glomeruli [797 nM (304)], and renal medulla [961 nM (363)], which may reflect biliary excretion and glomerular filtration. A high concentration of [3H]-paclitaxel was also noted in the choroid plexus [432 nM (167)], but [3H]-paclitaxel was not detected in the brain parenchyma, spinal cord, dorsal root ganglion, peripheral nerve, or the testicles. The pathogenesis of paclitaxel-induced neurotoxicity remains obscure given its limited distribution in the nervous system. In addition, these results suggest that systemically administered paclitaxel is not likely to be effective for the treatment of malignancies in the testes or the nervous system.

The chemotherapy of adult primary brain tumors

Adult patients with primary malignant brain tumors are a heterogeneous group. Most patients will have high-grade astrocytomas and can be expected to obtain minimal benefit from current standard chemotherapy regimens. Intra-arterial chemotherapy, high-dose chemotherapy with autologous bone marrow rescue, and new chemotherapeutic agents designed to penetrate the blood-brain barrier have not resulted in significant advances to date. However, there are exciting new directions in the chemotherapy of high-grade astrocytomas which are entering clinical trials. Two potentially promising approaches include interstitial chemotherapy using surgically implanted polymers and the continuous infusion of combinations of active chemotherapeutic agents. Other therapeutic modalities such as radioactive seed implants, stereotactic radiosurgery, and gene therapy are also being evaluated. Hopefully, this intense activity by subspecialists with a wide range of interests and expertise will produce novel and effective treatments for the large number of patients with malignant astrocytomas. In contrast, patients with many of the less common neoplasms of the central nervous system may benefit from the addition of chemotherapy to their treatment. Primary germ cell tumors or lymphomas of the central nervous system are very sensitive to chemotherapy. The germ cell tumors respond to the cisplatin-containing regimens developed for testicular malignancies. The optimal chemotherapy for CNS lymphoma is not clear but exciting results have been reported with a combination of radiation, systemic and intrathecal methotrexate, and systemic cytosine arabinoside. Although limited, the available literature suggests that patients with anaplastic oligodendrogliomas may also benefit from chemotherapy at diagnosis or at relapse. Studies in children suggest a benefit for adjuvant chemotherapy and radiation therapy in poor risk patients with medulloblastomas although these findings have not been confirmed in adults. Finally, anecdotal reports suggest that chemotherapy may be useful in the very rare patient who presents with a pineal tumor or an ependymoma.

Hydrophobicity of amino acid subgroups in proteins

Protein folding studies often utilize areas and volumes to assess the hydrophobic contribution to conformational free energy (Richards, F.M. Annu. Rev. Biophys. Bioeng. 6:151-176, 1977). We have calculated the mean area buried upon folding for every chemical group in each residue within a set of X-ray elucidated proteins. These measurements, together with a standard state cavity size for each group, are documented in a table. It is observed that, on average, each type of group buries a constant fraction of its standard state area. The mean area buried by most, though not all, groups can be closely approximated by summing contributions from three characteristic parameters corresponding to three atom types: (1) carbon or sulfur, which turn out to be 86% buried, on average; (2) neutral oxygen or nitrogen, which are 40% buried, on average; and (3) charged oxygen or nitrogen, which are 32% buried, on average.

Hydrophobicity of amino acid residues in globular proteins

During biosynthesis, a globular protein folds into a tight particle with an interior core that is shielded from the surrounding solvent. The hydrophobic effect is thought to play a key role in mediating this process: nonpolar residues expelled from water engender a molecular interior where they can be buried. Paradoxically, results of earlier quantitative analyses have suggested that the tendency for nonpolar residues to be buried within proteins is weak. However, such analyses merely classify residues as either "exposed" or "buried." In the experiment reported in this article proteins of known structure were used to measure the average area that each residue buries upon folding. This characteristic quantity, the average area buried, is correlated with residue hydrophobicity.