A Phase 1 Dose-Escalation Study of PF-06671008, a Bispecific T-Cell-Engaging Therapy Targeting P-Cadherin in Patients With Advanced Solid Tumors

P-cadherin is a cell-cell adhesion molecule that is overexpressed in several solid tumors. PF-06671008 is a T-cell–redirecting bispecific antibody that engages both P-cadherin on tumors and CD3ϵ on T cells and induces antitumor activity in preclinical models. We conducted a phase 1, open-label, first-in-human, dose-escalation study to characterize the safety and tolerability of PF-06671008, towards determining the recommended phase 2 dose. Adult patients with treatment-refractory solid tumors received PF-06671008 (1.5–400 ng/kg) as a weekly intravenous (IV) infusion on a 21-day/3-week cycle. Parallel cohorts evaluated dosing via subcutaneous injection (SC) or an IV-prime dose. Of the 27 patients enrolled in the study, 24 received PF-06671008 IV in escalating doses, two received SC, and one IV-prime. A dose-limiting toxicity of cytokine release syndrome (CRS) occurred in the 400-ng/kg IV group, prompting evaluation of SC and IV-prime schedules. In all, 25/27 patients who received PF-06671008 reported at least one treatment-related adverse event (TRAE); the most common were CRS (21/27), decreased lymphocyte count (9/27), and hypophosphatemia (8/27). Seven patients permanently discontinued treatment due to adverse events and no treatment-related deaths occurred. Cytokine peak concentrations and CRS grade appeared to positively correlate with C_max. Although the study was terminated due to limited antitumor activity, it provides important insights into understanding and managing immune-related adverse events resulting from this class of molecules.

The evolution of cyclin dependent kinase inhibitors in the treatment of cancer

INTRODUCTION

The cell cycle cyclin dependent kinases (CDKs) play a critical role in controlling the transition between cell cycle phases, as well as cellular transcription. Aberrant CDK activation is common in cancer, and deregulation of the cell cycle a key hallmark of cancer. Although CDK4/6 inhibitors are now a standard-of-care option for first- and second-line HR+HER2- metastatic breast cancer, resistance inevitably limits their clinical benefit.

AREAS COVERED

Early pan-CDK inhibitors targeted the cell cycle and RNA polymerase II phosphorylation, but were complicated by toxicity, providing a rationale and need for the development of selective CDK inhibitors. In this review, we highlight selected recent literature to provide a narrative review summarizing the current CDK inhibitor therapeutic landscape. We detail the challenges associated with targeting CDKs for the treatment of breast and other cancers and review emerging biomarkers that may aid response prediction. We also discuss the risk-benefit ratio for CDK therapy and explore promising combination approaches.

EXPERT OPINION

Although CDK inhibitors may stem the proliferation of cancer cells, resistance remains an issue, and currently there are limited biomarkers to predict response to therapy. Ongoing research investigating CDK inhibitors in cancer is of paramount importance to define appropriate and effective treatment regimens.

Model-Based Characterization of the Pharmacokinetics, Target Engagement Biomarkers, and Immunomodulatory Activity of PF-06342674, a Humanized mAb Against IL-7 Receptor-α, in Adults with Type 1 Diabetes

IL-7 receptor-α (IL-7Rα) blockade has been shown to reverse autoimmune diabetes in the non-obese diabetic mouse by promoting inhibition of effector T cells and consequently altering the balance of regulatory T (T_reg) and effector memory (T_EM) cells. PF-06342674 is a humanized monoclonal antibody that binds to and inhibits the function of IL-7Rα. In the current phase 1b study, subjects with type 1 diabetes (T1D) received subcutaneous doses of either placebo or PF-06342674 (1, 3, 8 mg/kg/q2w or 6 mg/kg/q1w) for 10 weeks and were followed up to 18 weeks. Nonlinear mixed effects models were developed to characterize the pharmacokinetics (PK), target engagement biomarkers, and immunomodulatory activity. PF-06342674 was estimated to have 20-fold more potent inhibitory effect on T_EM cells relative to T_reg cells resulting in a non-monotonic dose-response relationship for the T_reg:T_EM ratio, reaching maximum at ~ 3 mg/kg/q2w dose. Target-mediated elimination led to nonlinear PK with accelerated clearance at lower doses due to high affinity binding and rapid clearance of the drug-target complex. Doses ≥ 3 mg/kg q2w result in sustained PF-06342674 concentrations higher than the concentration of cellular IL-7 receptor and, in turn, maintain near maximal receptor occupancy over the dosing interval. The results provide important insight into the mechanism of IL-7Rα blockade and immunomodulatory activity of PF-06342674 and establish a rational framework for dose selection for subsequent clinical trials of PF-06342674. Furthermore, this analysis serves as an example of mechanistic modeling to support dose selection of a drug candidate in the early phases of development.

A phase 1, dose-escalation study of PF-06664178, an anti-Trop-2/Aur0101 antibody-drug conjugate in patients with advanced or metastatic solid tumors

Purpose and Methods Trop-2 is a glycoprotein over-expressed in many solid tumors but at low levels in normal human tissue, providing a potential therapeutic target. We conducted a phase 1 dose-finding study of PF-06664178, an antibody-drug conjugate that targets Trop-2 for the selective delivery of the cytotoxic payload Aur0101. The primary objective was to determine the maximum tolerated dose and recommended phase 2 dose. Secondary objectives included further characterization of the safety profile, pharmacokinetics and antitumor activity. Eligible patients were enrolled and received multiple escalating doses of PF-06664178 in an open-label and unblinded manner based on a modified continual reassessment method. Results Thirty-one patients with advanced or metastatic solid tumors were treated with escalating doses of PF-06664178 given intravenously every 21 days. Doses explored ranged from 0.15 mg/kg to 4.8 mg/kg. Seven patients experienced at least one dose limiting toxicity (DLT), either neutropenia or rash. Doses of 3.60 mg/kg, 4.2 mg/kg and 4.8 mg/kg were considered intolerable due to DLTs in skin rash, mucosa and neutropenia. Best overall response was stable disease in 11 patients (37.9%). None of the patients had a partial or complete response. Systemic exposure of PF-06664178 increased in a dose-related manner. Serum concentrations of free Aur0101 were substantially lower than those of PF-06664178 and total antibody. No correlation of Trop-2 expression and objective response was observed, although Trop-2 overexpression was not required for study entry. The intermediate dose of 2.4 mg/kg appeared to be the highest tolerated dose, but this was not fully explored as the study was terminated early due to excess toxicity. Conclusion PF-06664178 showed toxicity at high dose levels with modest antitumor activity. Neutropenia, skin rash and mucosal inflammation were dose limiting toxicities. Findings from this study may potentially aid in future antibody drug conjugate design and trials.

Effect of a kappa-opioid agonist, i.v. JNJ-38488502, on sensation of colonic distensions in healthy male volunteers

Kappa-opioid receptors are located on visceral pain fibres. JNJ-38488502 is a highly selective tetrapeptide kappa-opioid agonist with little access to the central nervous system and low risk of central nervous system side effects. The aim of the study was to evaluate the effects of i.v. JNJ-38488502 on sensations, including pain, during colonic distension. In a single-centre study, 23 healthy adult males underwent a single-dose, randomized, double-blind crossover study of JNJ-38488502 (0.42 mg kg(-1) i.v. infusion) vs placebo on left colon compliance, sensory thresholds and ratings during standard distensions. One participant could not undergo sensation studies. In the other 22, JNJ-38488502 increased colonic compliance (pressure at half-maximum volume 17.9 +/- 0.8 mmHg) compared to placebo (21.6 +/- 0.9 mmHg, P = 0.007). There was no significant effect on sensory thresholds which, however, were not reached by 44 mmHg in >50% of participants in both treatment phases. There were no significant treatment effects on sensory ratings to distensions at 8, 16, 24, 32 and 36 mmHg above baseline operating pressure. JNJ-38488502 was associated with increased urine output and plasma prolactin, consistent with kappa-opioid receptor activation. This study concluded that i.v. JNJ-38488502 induced kappa-opioid effects, but did not attenuate colonic sensations following random order colonic distension. Further studies of effects on pain sensations in health and disease are required.

Use of a lidocaine patch in the management of postsurgical neuropathic pain in patients with cancer: a phase III double-blind crossover study (N01CB)

OBJECTIVE

Current therapies often have limited efficacy and untenable side effects when used to treat persistent incisional pain following cancer-related surgery. Lidocaine patches reduce neuropathic pain from herpes zoster but their benefits for persistent cancer-related postsurgical incisional pain remain unclear.

STUDY DESIGN

Multicenter, double-blind, randomized, two-period crossover trial.

MATERIALS AND METHODS

Twenty-eight cancer patients with postsurgical incisional pain were randomly assigned to receive either lidocaine patches followed by placebo patches or the reverse. Each study period lasted 4 weeks. Patches were applied daily upon waking and left in place for a maximum of 18 h. The primary outcome measure, an 11-point pain intensity rating scale, was administered weekly. Secondary outcomes were administered weekly (Brief Pain Inventory-Short Form(BPI-SF), Subject Global Impression of Change) and at the end of each study period (Short Form-Magill Pain Questionnaire, Linear Analogue Self Assessment Scale, Neuropathy Pain Scale, Pain Catastrophizing Scale, Profile of Mood States Short Form).

RESULTS

Twenty-one patients completed the first period and 18 completed their crossover second phase. No significant intergroup differences were detected in pain intensity ratings. Few secondary end points were significantly different when subjects used the lidocaine versus placebo patches. BPI-SF interference scores were lower in patients using the lidocaine patch during the first study period, including several scores that achieved statistical significance, general activity (p = 0.02), work (p = 0.04), and relations with others (p = 0.02).

CONCLUSION

Lidocaine patch use did not significantly reduce pain intensity ratings or the majority of related secondary end points in cancer patients with persistent incisional pain.

Efficacy of lamotrigine in the management of chemotherapy-induced peripheral neuropathy: a phase 3 randomized, double-blind, placebo-controlled trial, N01C3

BACKGROUND

Lamotrigine, an antiepileptic agent, has been reported as being effective in reducing symptoms of neuropathy associated with various etiologies. Based on such data, a multicenter double-blind, placebo-controlled, randomized trial was conducted to evaluate the effect of lamotrigine on pain and other neuropathic symptoms due to chemotherapy-induced peripheral neuropathy (CIPN).

METHODS

Patients with symptomatic CIPN with symptom scores of either 1) >3 on a 0-10 Numerical Rating Scale (NRS) or 2) >1 on the 0-3 the Eastern Cooperative Oncology Group (ECOG) neuropathy scale (ENS) were eligible (higher numbers corresponding to greater severity of symptoms in both scales). Patients were randomly assigned to receive lamotrigine (target dose of 300 mg/day) or placebo for 10 weeks. Endpoints were measured biweekly.

RESULTS

In all, 131 patients were enrolled. Both groups were well matched at baseline. Over the 10-week period of the trial, the average pain scores (NRS) for the lamotrigine and placebo arms declined in both arms, with no statistically significant difference noted between the changes in the 2 groups (0.3 and 0.5 unit reduction from baseline, respectively; P=.56). Similarly, decreases in the ENS with therapy were not statistically different (0.4 and 0.3, respectively; P=.3). Changes in other subjective symptom scales were also not found to be statistically different between the 2 groups. Toxicities were mild and similar in each group.

CONCLUSIONS

The results suggest that lamotrigine is not effective for relieving neuropathic symptoms in patients because of CIPN.

Hearing Loss and Cerebrospinal Fluid Pressure: Case Report and Review of the Literature

A decrease in cerebrospinal fluid pressure may result in an endolymphatic hydrops through a patent cochlear aqueduct or through the fundus of the internal auditory canal. This hydrops typically leads to low-frequency sensorineural hearing loss. We describe the case of a man who presented with a subjective and objective hearing loss in addition to a headache 4 days after he had undergone a dural puncture. We treated him with a standard epidural blood patch. Immediately after treatment, his hearing improved and his headache resolved.

Hearing loss and cerebrospinal fluid pressure: case report and review of the literature

A decrease in cerebrospinal fluid pressure may result in an endolymphatic hydrops through a patent cochlear aqueduct or through the fundus of the internal auditory canal. This hydrops typically leads to low-frequency sensorineural hearing loss. We describe the case of a man who presented with a subjective and objective hearing loss in addition to a headache 4 days after he had undergone a dural puncture. We treated him with a standard epidural blood patch. Immediately after treatment, his hearing improved and his headache resolved.

Efficacy of gabapentin in the management of chemotherapy-induced peripheral neuropathy: a phase 3 randomized, double-blind, placebo-controlled, crossover trial (N00C3)

BACKGROUND

The antiepileptic agent, gabapentin, has been demonstrated to relieve symptoms of peripheral neuropathy due to various etiologies. On the basis of these data, a multicenter, double-blind, placebo-controlled, crossover, randomized trial was conducted to evaluate the effect of gabapentin on symptoms of chemotherapy-induced peripheral neuropathy (CIPN).

METHODS

Patients with symptomatic CIPN who complained of 'average' daily pain scores of either 1) >/=4 on a 0-10 numerical rating scale (NRS); or 2) >/=1 on the 0-3 Eastern Cooperative Oncology Group neuropathy scale (ENS) were eligible (higher numbers indicate greater severity of symptoms in both scales). Patients were randomized to receive gabapentin (target dose, 2700 mg) or placebo for 6 weeks. Crossover occurred after a 2-week washout period. CIPN-related symptoms were evaluated weekly by questionnaires. Statistical methods followed established methods for crossover designs, including Student t tests to compare average intrapatient differences between treatments and linear models to adjust for potential concomitant covariates.

RESULTS

There were 115 patients who were randomly assigned to the treatment or control arm. Both groups were well matched by symptoms at study entry. Changes in symptom severity were statistically similar between the 2 groups during the study. Adverse events were mild and similar in both groups.

CONCLUSIONS

This trial failed to demonstrate any benefit to using gabapentin to treat symptoms caused by CIPN.

Precision of health-related quality-of-life data compared with other clinical measures

To many clinicians, the assessment of health-related quality of life (HRQL) seems more art than science. This belief is due in part to the lack of formal training available to clinicians regarding HRQL measurement and interpretation. When HRQL is used systematically, it has been shown to improve patient-physician communication, clinical decision making, and satisfaction with care. Nevertheless, clinicians rarely use formal HRQL data in their practices. One major reason is unfamiliarity with the interpretation and potential utility of the data. This unfamiliarity causes a lack of appreciation for the reliability of data generated by formal HRQL assessment and a tendency to regard HRQL data as having insufficient precision for individual use. This article discusses HRQL in the larger context of health indicators and health outcome measurement and is targeted to the practicing clinician who has not had the opportunity to understand and use HRQL data. The concept and measurement of reliability are explained and applied to HRQL and common clinical measures simultaneously, and these results are compared with one another. By offering a juxtaposition of common medical measurements and their associated error with HRQL measurement error, we note that HRQL instruments are comparable with commonly used clinical data. We further discuss the necessary requirements for clinicians to adopt formal, routine HRQL assessment into their practices.

Validation of the S-LANSS in the community setting

The Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS), an assessment tool to determine if pain is predominantly neuropathic, has not been validated in a community setting. Previously identified residents of Olmsted County, Minnesota, with chronic pain were recruited using a stratified randomization process to increase the frequency of neuropathic pain in the study sample. Subjects completed the S-LANSS in mailed and telephone formats, and underwent clinical assessment to determine if a component of their pain was neuropathic. Sensitivity and specificity of the S-LANSS as compared to the clinical assessment were determined. Two hundred and five subjects participated in the study. Eighty-three subjects (40%) had a positive S-LANSS score in the mailed, as did 59 of 173 (34%) in the telephone format, with little inter-subject difference in scores (p=0.57). Clinical assessment identified a component of neuropathic pain in 37% of the sample (75/205). Compared to clinical assessment, sensitivity and specificity in the mailed S-LANSS were 57% (95% CI, 46-69%) and 69% (95% CI, 61-77%), respectively, and in the telephone S-LANSS were 52% (95% CI, 39-64%) and 78% (95% CI, 68-85%), respectively. The sensitivity and specificity of the S-LANSS in both formats were lower than the initial S-LANSS validation study. Differences in survey format and subject population could account for these differences, suggesting that the S-LANSS is best suited as a screening tool and its use to determine the prevalence of neuropathic pain in population studies should be viewed cautiously.

Transabdominal ultrasound assessment of the fetal head and the accuracy of vacuum cup application

OBJECTIVE

To investigate whether the accuracy of vacuum cup placement can be improved by intrapartum ultrasound assessment of the fetal head position during the second stage of labor prior to vacuum extraction for prolonged second stage.

METHODS

50 women undergoing vacuum extraction for prolonged second stage were randomly allocated to either digital examination (n=25) or digital examination together with transabdominal intrapartum ultrasound (n=25) prior to vacuum extraction by the attending obstetrician. The distance between the centre of the chignon and the flexion point was then measured by a midwife immediately after delivery. The flexion point was defined as 6 cm posterior to the anterior fontanelle or 3 cm anterior to the posterior fontanelle.

RESULTS

There were no statistically significant differences in the demographic data, duration of labor, incidence of induction/augmentation, and intrapartum complications between the two groups. The mean distance between the centre of the chignon and the flexion point was 2.1+/-1.3 cm in the group with digital examination and ultrasound assessment and 2.8+/-1.0 cm in the group with digital examination alone. The difference in the mean distance between the two groups was statistically significant (p=0.039).

CONCLUSION

Intrapartum transabdominal ultrasound assessment of the fetal head position during the second stage of labor improves the accuracy of vacuum cup placement during vacuum extraction for prolonged second stage.

Intravenous paclitaxel administration in the rat induces a peripheral sensory neuropathy characterized by macrophage infiltration and injury to sensory neurons and their supporting cells

Paclitaxel-induced peripheral neuropathy (PN) can be a significant problem for patients receiving chemotherapeutic regimens for the treatment of breast, ovarian, and lung cancer as PN can influence the quality of life and survivorship in these patients. To begin to understand the cellular changes that occur within the peripheral and central nervous system as PN develops, we intravenously infused rats with clinically relevant doses of paclitaxel. Ten days later, behavioral changes indicative of PN became evident that included mechanical allodynia, cold hyperalgesia, and deficits in ambulation/coordination. These behaviors were accompanied by increased expression of activating transcription factor 3 (ATF3; a marker of cellular injury) in a population of large>medium>small diameter sensory neurons, a population of satellite cells in the lumbar dorsal root ganglia (DRG) and in myelinating Schwann cells in the sciatic nerve. In addition, there was an increase in the expression of glial fibrillary acidic protein (GFAP) in DRG satellite cells and an increase in the number of CD68 positive activated macrophages within the DRG and peripheral nerve. Within lamina III-IV of the lumbar spinal cord, there was an increase in OX42 positive microglia. These data suggest that intravenous infusion of paclitaxel induces a peripheral neuropathy characterized by injury of neuronal and non-neuronal cells in the peripheral nervous system, macrophage activation in both the DRG and peripheral nerve, and microglial activation within the spinal cord. An understanding of the factors involved in the development and maintenance of PN may lead to mechanism based therapies that prevent/treat PN and thus improve the survival and quality of life of patients receiving chemotherapy.

Gabapentin for smoking cessation: A preliminary investigation of efficacy

Gabapentin affects the glutamate and gamma amino butyric acid (GABA) neurotransmitters through which it may facilitate smoking abstinence. To obtain preliminary estimates of efficacy of gabapentin for smoking cessation, we conducted a single-arm, open-label study of gabapentin, 1,800-mg/day administered in three equal divided doses for 8 weeks. A total of 50 adult smokers were enrolled. All participants received a brief behavioral intervention at each medication visit. A total of 37 participants completed all follow-up assessments. At end-of-treatment the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 28% (95% CI=16%-42%) and 24% (95% CI=13%-38%), respectively. At 6 months, the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 20% (95% CI=10%-34%) and 16% (95% CI=7%-29%), respectively. Among subjects who continued to smoke and completed the follow-up assessments, the reported number of cigarettes smoked per day (mean+/-standard deviation) was significantly less than at baseline: -10.0+/-8.2 (p<.001). Adverse effects were minor and well tolerated. Our results suggest that gabapentin may increase smoking abstinence. An adequately powered randomized clinical trial assessing different doses of this drug against a placebo would be the reasonable next step.

Painful metastases involving bone: percutaneous image-guided cryoablation--prospective trial interim analysis

PURPOSE

To prospectively determine the safety and effectiveness of percutaneous cryoablation for the reduction of pain, improvement in the activities of daily life, and reduction in the use of analgesic medications for patients with painful metastatic lesions involving bone.

MATERIALS AND METHODS

This study was compliant with HIPAA and was approved by the institutional review board. Written informed consent was obtained. During 18 months, 14 patients (eight men, six women; age range, 21-72 years; mean age, 54 years) with one or two painful metastatic lesions involving bone, with a score of 4 or greater out of 10 for worst pain in a 24-hour period, and who did not respond to or refused conventional radiation treatment or chemotherapy were treated with percutaneous cryoablation. Patient response was measured with the Brief Pain Inventory, and analgesic use was recorded before and after the procedure at days 1 and 4, weekly for 4 weeks, and then every other week for a total of 6 months. Complications were monitored. Analysis of the primary end points was undertaken with paired comparison procedures by using paired t tests across individual time points supplemented with repeated measures analysis of variance.

RESULTS

Treated lesions were 1-11 cm in diameter. Before cryoablation, the mean score for worst pain in a 24-hour period was 6.7 of 10; the score decreased to 3.8 (P = .003) 4 weeks after treatment. Mean pain interference with activities of daily living was 5.5 of 10 before treatment and decreased to 3.2 (P = .004) 4 weeks after treatment. All eight (100%) patients (exact 95% binomial confidence interval: 63%, 100%) for whom narcotics were prescribed prior to the procedure reported a reduction in these medications after cryoablation. No serious complications were observed.

CONCLUSION

Percutaneous cryoablation is a safe and effective method for palliation of pain due to metastatic disease involving bone.

Three-dimensional ultrasound findings of spondylocostal dysostosis in the second trimester of pregnancy

Spondylocostal dysostosis (SCD) is a rare congenital disorder that is characterized by vertebral segmentation and formation defects, and asymmetrical rib anomalies. We describe a case diagnosed during the second trimester of pregnancy with the sonographic features of abnormal alignment of the spine, hemivertebrae in the thoracic spine and kyphoscoliosis. Three-dimensional ultrasound demonstrated a 'fan-like' rib cage with fusion of the ribs. The postmortem findings confirmed the ultrasound findings and were consistent with SCD.

A quantitative analysis of the sensory and sympathetic innervation of the mouse pancreas

Pain from pancreatitis or pancreatic cancer can be both chronic and severe although little is known about the mechanisms that generate and maintain this pain. To define the peripheral sensory and sympathetic fibers involved in transmitting and modulating pancreatic pain, immunohistochemistry and confocal microscopy were used to examine the sensory and sympathetic innervation of the head, body and tail of the normal mouse pancreas. Myelinated sensory fibers were labeled with an antibody raised against 200 kD neurofilament H (clone RT97), thinly myelinated and unmyelinated peptidergic sensory fibers were labeled with antibodies raised against calcitonin gene-related peptide (CGRP) and post-ganglionic sympathetic fibers were labeled with an antibody raised against tyrosine hydroxylase (TH). RT97, CGRP, and TH immunoreactive fibers were present in parenchyma of the head, body and tail of the pancreas with the relative density of both RT97 and CGRP expressing fibers being head>body>tail, whereas for TH, a relatively even distribution was observed. In all three regions of the pancreas, RT97 fibers were associated mainly with large blood vessels, the CGRP fibers were associated with the large- and medium-sized blood vessels and the TH were associated with the large- and medium-sized blood vessels as well as capillaries. In addition to this extensive set of sensory and sympathetic nerve fibers that terminate in the pancreas, there were large bundles of en passant nerve fibers in the dorsal region of the pancreas that expressed RT97 or CGRP and were associated with the superior mesenteric plexus. These data suggest the pancreas receives a significant sensory and sympathetic innervation. Understanding the factors and disease states that sensitize and/or directly excite the nerve fibers that terminate in the pancreas as well as those that are en passant may aid in the development of therapies that more effectively modulate the pain that frequently accompanies diseases of the pancreas, such as pancreatitis and pancreatic cancer.

Pancreatic cancer pain and its correlation with changes in tumor vasculature, macrophage infiltration, neuronal innervation, body weight and disease progression

To begin to understand the relationship between disease progression and pain in pancreatic cancer, transgenic mice that develop pancreatic cancer due to the expression of the simian virus 40 large T antigen under control of the rat elastase-1 promoter were examined. In these mice precancerous cellular changes were evident at 6 weeks and these included an increase in: microvascular density, macrophages that express nerve growth factor and the density of sensory and sympathetic fibers that innervate the pancreas, with all of these changes increasing with tumor growth. In somatic tissue such as skin, the above changes would be accompanied by significant pain; however, in mice with pancreatic cancer, changes in pain-related behaviors, such as morphine-reversible severe hunching and vocalization only became evident at 16 weeks of age, by which time the pancreatic cancer was highly advanced. These data suggest that in mice as well as humans, there is a stereotypic set of pathological changes that occur as pancreatic cancer develops, and while weight loss generally tracks disease progression, there is a significant lag between disease progression and behaviors indicative of pancreatic cancer pain. Defining the mechanisms that mask this pain in early and mid-stage disease and drive the pain in late-stage disease may aid in earlier diagnosis, survival, and increased quality of life of patients with pancreatic cancer.

Effect of neurolytic celiac plexus block on pain relief, quality of life, and survival in patients with unresectable pancreatic cancer: a randomized controlled trial

CONTEXT

Pancreatic cancer is an aggressive tumor associated with high mortality. Optimal pain control may improve quality of life (QOL) for these patients.

OBJECTIVE

To test the hypothesis that neurolytic celiac plexus block (NCPB) vs opioids alone improves pain relief, QOL, and survival in patients with unresectable pancreatic cancer.

DESIGN, SETTING, AND PATIENTS

Double-blind, randomized clinical trial conducted at Mayo Clinic, Rochester, Minn. Enrolled (October 1997 and January 2001) were 100 eligible patients with unresectable pancreatic cancer experiencing pain. Patients were followed up for at least 1 year or until death.

INTERVENTION

Patients were randomly assigned to receive either NCPB or systemic analgesic therapy alone with a sham injection. All patients could receive additional opioids managed by a clinician blinded to the treatment assignment.

MAIN OUTCOME MEASURES

Pain intensity (0-10 numerical rating scale), QOL, opioid consumption and related adverse effects, and survival time were assessed weekly by a blinded observer.

RESULTS

Mean (SD) baseline pain was 4.4 (1.7) for NCPB vs 4.1 (1.8) for opioids alone. The first week after randomization, pain intensity and QOL scores were improved (pain intensity, P< or =.01 for both groups; QOL, P<.001 for both groups), with a larger decrease in pain for the NCPB group (P =.005). From repeated measures analysis, pain was also lower for NCPB over time (P =.01). However, opioid consumption (P =.93), frequency of opioid adverse effects (all P>.10), and QOL (P =.46) were not significantly different between groups. In the first 6 weeks, fewer NCPB patients reported moderate or severe pain (pain intensity rating of > or =5/10) vs opioid-only patients (14% vs 40%, P =.005). At 1 year, 16% of NCPB patients and 6% of opioid-only patients were alive. However, survival did not differ significantly between groups (P =.26, proportional hazards regression).

CONCLUSION

Although NCPB improves pain relief in patients with pancreatic cancer vs optimized systemic analgesic therapy alone, it does not affect QOL or survival.

Percutaneous image-guided radiofrequency ablation of painful metastases involving bone: a multicenter study

PURPOSE

Few options are available for pain relief in patients with bone metastases who fail standard treatments. We sought to determine the benefit of radiofrequency ablation (RFA) in providing pain relief for patients with refractory pain secondary to metastases involving bone.

PATIENTS AND METHODS

Thirty-one US and 12 European patients with painful osteolytic metastases involving bone were treated with image-guided RFA using a multitip needle. Treated patients had > or = 4/10 pain and had either failed or were poor candidates for standard treatments such as radiation or opioid analgesics. Using the Brief Pain Inventory-Short Form, worst pain intensity was the primary end point, with a 2-unit drop considered clinically significant.

RESULTS

Forty-three patients were treated (median follow-up, 16 weeks). Before RFA, the mean score for worst pain was 7.9 (range, 4/10 to 10/10). Four, 12, and 24 weeks following treatment, worst pain decreased to 4.5 (P <.0001), 3.0 (P <.0001), and 1.4 (P =.0005), respectively. Ninety-five percent (41 of 43 patients) experienced a decrease in pain that was considered clinically significant. Opioid usage significantly decreased at weeks 8 and 12. Adverse events were seen in 3 patients and included (1) a second-degree skin burn at the grounding pad site, (2) transient bowel and bladder incontinence following treatment of a metastasis involving the sacrum, and (3) a fracture of the acetabulum following RFA of an acetabular lesion.

CONCLUSION

RFA of painful osteolytic metastases provides significant pain relief for cancer patients who have failed standard treatments.

Painful metastases involving bone: feasibility of percutaneous CT- and US-guided radio-frequency ablation

PURPOSE

To determine the safety and efficacy of radio-frequency (RF) ablation for pain reduction, quality of life improvement, and analgesics use reduction in patients with skeletal metastases.

MATERIALS AND METHODS

Over 10 months, 12 adult patients with a single painful osteolytic metastasis in whom radiation therapy or chemotherapy had failed and who reported severe pain (pain score > or = 4 [scale of 0-10]) over a 24-hour period were treated with percutaneous imaging-guided RF ablation with a multi-tined electrode while under general anesthesia. Patient pain was measured with a Brief Pain Inventory 1 day after the procedure, every week for 1 month, and thereafter every other week (total follow-up, 6 months). Patient analgesics use was also recorded at these follow-up intervals. Follow-up contrast material-enhanced computed tomography was performed 1 week after the procedure. Complications were monitored. Analysis of the primary end point was undertaken with paired comparison procedures.

RESULTS

Lesion size was 1-11 cm. Before RF ablation, mean worst pain score in a 24-hour period in 12 patients was 8.0 (range, 6-10). At 4 weeks after treatment, mean worst pain decreased to 3.1 (P =.001). Mean pain before treatment was 6.5 and decreased to 1.8 (P <.001) 4 weeks after treatment. Mean pain interference in general activity decreased from 6.6 to 2.7 (P =.002) 4 weeks after treatment. Eight of 10 patients using analgesics reported reduced use at some time after RF ablation. No serious complications were observed.

CONCLUSION

RF ablation of painful osteolytic metastases is safe, and the relief of pain is substantial.

Patient, clinician, and population perspectives on determining the clinical significance of quality-of-life scores

Despite the success of screening and treatment of major cancers in the United States, cancer remains a chronic condition dominated by symptoms and treatment-related adverse effects. Because of these often taxing symptoms and adverse effects, numerous studies have been conducted to document the effects of cancer diagnosis and treatment on the quality of life (QOL) of patients. But there has been limited investigation of the clinical significance of QOL scores. This article examines the clinical significance of QOL scores from 3 key perspectives: patients, clinicians, and the general population. The patient's perspective includes an evaluation of the size of difference in scores that individual patients can detect and regard as important. The clinician perspective relies on whether the clinician believes the patient's condition has stayed the same vs whether changes have occurred (decline or improvement). The population perspective represents a democratic process in which the input or votes of a community of people are used to determine if health state A is clinically significantly different from health state B. While many clinicians and researchers advocate for QOL to be defined from the patient's perspective, the reality is that QOL is often defined by clinicians in terms of observable events. Even when measures are used in which the patient identifies how his or her life has been affected, it is often the clinician who interprets the clinical importance of this information. The clinician's perspective has value in framing an experience within the context of what is usual for a group of individuals, and the population perspective provides inputs as to how society may use limited resources. However, we conclude that a more prominent role for the patient's QOL perspective is needed.

Neurophysiologic influences on hamstring flexibility: a pilot study

OBJECTIVE

To examine the potential contribution of neurologic influences on hamstring length during passive range of motion.

DESIGN

Prospective study.

SETTINGS

Academic sports medicine center.

PATIENTS

15 subjects undergoing arthroscopic surgery for unilateral knee injuries without previous injury to the contralateral knee.

INTERVENTIONS

Subjects received: 1) spinal anesthesia with bupivacaine, 2) epidural anesthesia with lidocaine, 3) general anesthesia, or 4) femoral nerve block of injured leg only.

MAIN OUTCOME MEASURES

Noninjured leg popliteal angle preoperatively, intraoperatively under anesthesia, and postoperatively after recovery from anesthesia.

RESULTS

The overall mean popliteal angle was 132.5 +/- 3.1 degrees preoperatively, 134.31 +/- 11.6 degrees intraoperatively, and 130.7 +/- 10.2 degrees postoperatively. Overall, the intraoperative angle was significantly greater than the postoperative angle (p = 0.02). The mean change in popliteal angle was 8.1 +/- 2.2 degrees (Group 1), -0.4 +/- 1.9 degrees (Group 2), 0.9 +/- 1.4 degrees (Group 3), and -2.4 +/- 3.8 degrees (Group 4). There was no significant change in pre- to postoperative popliteal angle in relation to postoperative pain. Females had a greater mean popliteal angle (139.84 degrees ) compared with males (128.84 degrees ) (p = 0.04).

CLINICAL RELEVANCE

Understanding the neuromuscular influences on muscle flexibility will assist in the development of new rehabilitative and injury preventative techniques.

CONCLUSION

The present pilot study implicates neural contributions to muscle flexibility. Further studies are needed to delineate the relative contributions of neural and muscular components and to facilitate new techniques in the rehabilitation and prevention of injury.

Risk of surgery and anesthesia for ischemic stroke

BACKGROUND

The goal of this study was to determine if the combination of surgery and anesthesia is an independent risk factor for the development of incident (first-time) ischemic stroke.

METHODS

All residents of Rochester, MN, with incident ischemic stroke from 1960 through 1984 (1,455 cases and 1,455 age- and gender-matched controls) were used to identify risk factors associated with ischemic stroke. Cases and controls undergoing surgery involving general anesthesia or central neuroaxis blockade before their stroke/index date of diagnosis were identified. A conditional logistic regression model was used to estimate the odds ratio of surgery and anesthesia for ischemic stroke while adjusting for other known risk factors.

RESULTS

There were 59 cases and 17 controls having surgery within 30 days before their stroke/index date. After adjusting for previously identified risk factors, surgery within 30 days before the stroke/index date (perioperative period) was found to be an independent risk factor for stroke (P<0.001; odds ratio, 3.9; 95% confidence interval, 2.1-7.4). In an analysis that excluded matched pairs where the case and/or control underwent surgery considered "high risk" for stroke (cardiac, neurologic, or vascular procedures), "non-high-risk surgery" was also found to be an independent risk factor for perioperative stroke (P = 0.002; odds ratio, 2.9; 95% confidence interval, 1.5-5.7).

CONCLUSION

Our results suggest that there is an increased risk of ischemic stroke in the 30 days after surgery and anesthesia. This risk remains elevated even after excluding surgeries (cardiac, neurologic, and vascular surgeries) considered to be high risk for ischemic stroke.

Palliation of pain in chronic pancreatitis. Use of neural blocks and neurotomy

Effective management of the pain of chronic pancreatitis may require a multidisciplinary approach involving gastroenterologists, anesthesiologists, psychologists or counselors for chemical addiction (alcohol, narcotics), and surgeons. Viable approaches use pharmacologic analgesics with selected psychotropic medications, celiac plexus blocks, and possibly thoracoscopic splanchnic nerve transections. If these management techniques that preserve pancreatic parenchyma and function, fail, resective surgical therapy may be indicated. For most of these patients, all attempts at nonresective therapy should be exhausted before operative intervention.

A randomized trial of naltrexone for smoking cessation

AIMS

To evaluate the efficacy and safety of orally administered naltrexone, alone or in combination with nicotine patches, as a treatment for cigarette smoking.

DESIGN

Randomized, partially-blinded, 2 x 2 factorial trial using naltrexone (active vs. placebo) and nicotine patches (active vs. none).

PARTICIPANTS

One hundred cigarette smokers.

INTERVENTION

Twelve weeks of either placebo-only, naltrexone-only, placebo with nicotine patches or naltrexone with nicotine patches. The naltrexone dose was 50 mg taken once daily, and the nicotine patch dose was 21 mg/24-hour for the first 8 weeks and 14 mg/24-hour for the remaining 4 weeks. Brief behavioral intervention was provided at each visit.

MEASUREMENTS

One-week point-prevalence smoking abstinence rates confirmed by an expired air carbon monoxide level of 8 parts per million (ppm) or less, daily cigarette smoking and cigarette craving.

FINDINGS

At the end of treatment, there was no effect of naltrexone on smoking abstinence. The smoking abstinence rates were 19% and 22% for the placebo only and naltrexone only treatment groups, respectively, and 48% and 46% for the placebo with nicotine patch and naltrexone with nicotine patch groups, respectively. However, the effect of the nicotine patch at this time was significant (p = 0.006), but not at the 6-month follow-up. No significant effect of naltrexone was observed on daily cigarette smoking on cigarette craving during the study.

CONCLUSIONS

The opioid antagonist naltrexone was not found to be effective for smoking cessation and had no significant effect on daily cigarette consumption or craving. The results of the present study provide no support for the use of naltrexone, alone or in combination with nicotine patches, as a therapeutic treatment for smoking cessation.

cGMP modulation of Ca2+ sensitivity in airway smooth muscle

A beta-escin-permeabilized canine tracheal smooth muscle preparation was used to test the hypothesis that cGMP decreases Ca2+ sensitivity in airway smooth muscle primarily by inhibiting the membrane receptor-coupled mechanisms that regulate Ca2+ sensitivity and not by inhibiting Ca2+/calmodulin activation of the contractile proteins. 8-Bromo-cGMP (100 microM) had no effect on the free Ca2+ concentration-response curves generated in the absence of muscarinic receptor stimulation. In the presence of 100 microM ACh plus 10 microM GTP, 8-bromo-cGMP (100 microM) caused a rightward shift of the free Ca2+ concentration-response curve, significantly increasing the EC50 for free Ca2+ from 0.35 +/- 0.03 to 0.75 +/- 0.06 microM; this effect of 8-bromo-cGMP was concentration dependent from 1 to 100 microM. 8-Bromo-cGMP (100 microM) decreased the level of regulatory myosin light chain (rMLC) phosphorylation for a given cytosolic Ca2+ concentration but had no effect on the amount of isometric force produced for a given level of rMLC phosphorylation. These findings suggest that cGMP decreases Ca2+ sensitivity in canine tracheal smooth muscle primarily by inhibiting the membrane receptor-coupled mechanisms that modulate the relationship between cytosolic Ca2+ concentration and rMLC phosphorylation.

Infraclavicular brachial plexus block: parasagittal anatomy important to the coracoid technique

Infraclavicular brachial plexus block is a technique well suited to prolonged continuous catheter use. We used a coracoid approach to this block to create an easily understood technique. We reviewed the magnetic resonance images of the brachial plexus from 20 male and 20 female patients. Using scout films, the parasagittal section 2 cm medial to the coracoid process was identified. Along this oblique section, we located a point approximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall. From this point, we determined simulated needle direction to contact the neurovascular bundle and measured depth. At the skin entry site, the direct posterior insertion of a needle will make contact with the cords of the brachial plexus where they surround the second part of the axillary artery in all images. The mean (range) distance (depth along the needle shaft) from the skin to the anterior wall of the axillary artery was 4.24 +/- 1.49 cm (2.25-7.75 cm) in men and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. Hopefully, this study will facilitate the use of this block.

IMPLICATIONS

We sought a consistent, palpable landmark for facilitation of the infraclavicular brachial plexus block. We used magnetic resonance images of the brachial plexus to determine the depth and needle orientation needed to contact the brachial plexus. Hopefully, this study will facilitate the use of this block.

Dose-ranging study of indole-3-carbinol for breast cancer prevention

Sixty women at increased risk for breast cancer were enrolled in a placebo-controlled, double-blind dose-ranging chemoprevention study of indole-3-carbinol (I3C). Fifty-seven of these women with a mean age of 47 years (range 22-74) completed the study. Each woman took a placebo capsule or an I3C capsule daily for a total of 4 weeks; none of the women experienced any significant toxicity effects. The urinary estrogen metabolite ratio of 2-hydroxyestrone to 16 alpha-hydroxyestrone, as determined by an ELISA assay, served as the surrogate endpoint biomarker (SEB). Perturbation in the levels of SEB from baseline was comparable among women in the control (C) group and the 50, 100, and 200 mg low-dose (LD) group. Similarly, it was comparable among women in the 300 and 400 mg high-dose (HD) group. Regression analysis showed that peak relative change of SEB for women in the HD group was significantly greater than that for women in the C and LD groups by an amount that was inversely related to baseline ratio; the difference at the median baseline ratio was 0.48 with 95% confidence interval (0.30, 0.67). No other factors, such as age and menopausal status, were found to be significant in the regression analysis. The results in this study suggest that I3C at a minimum effective dose schedule of 300 mg per day is a promising chemopreventive agent for breast cancer prevention. A larger study to validate these results and to identify an optimal effective dose schedule of I3C for long-term breast cancer chemoprevention will be necessary.

Defining the cross-sectional anatomy important to interscalene brachial plexus block with magnetic resonance imaging

BACKGROUND AND OBJECTIVES

Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being "perpendicular to the skin in every plane" (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block.

METHODS

Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6-C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient.

RESULTS

The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 +/- 6.1 degrees (range, 50-78 degrees). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6-C7 level.

CONCLUSIONS

These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.

Referral of patients with pain from pancreatic cancer for neurolytic celiac plexus block

OBJECTIVE

To assess whether patients with pancreatic cancer-associated pain living near a pain control center were more likely to undergo neurolytic celiac plexus block (NCPB) than those living at a distance and to determine the rationale of physicians at our institution for referring patients for NCPB.

DESIGN

We retrospectively reviewed the frequency of use of NCPB in patients with pancreatic cancer and conducted an anonymous physician survey of referral patterns for NCPB for such patients.

MATERIAL AND METHODS

A prospective database of medical diagnoses and a clinical database at our institution were used to identify patients with pancreatic cancer within three geographic regions who were assessed during the inclusive years 1980 through 1989: group I ("local") = all patient with pancreatic cancer in Olmsted County, Minnesota; group II ("surrounding") and group III ("distant") = patients referred for pancreatic cancer evaluation who lived within 100 miles of our institution (excluding Olmsted County) or more than 100 miles from our institution, respectively. Medical records were retrospectively reviewed to assess the use of NCPB at any time during the course of pancreatic cancer. For the physician survey component, all medical oncologists, gastroenterologists, and general surgeons at our institution who might be responsible for the care of patients with pancreatic cancer were sent a questionnaire about their referral patterns for NCPB among patients with pancreatic cancer.

RESULTS

Overall, approximately 15% of the 292 patients with pancreatic cancer studied underwent NCPB. Distance from our pain control center was not found to be associated with frequency of use of NCPB. Of the 78 physicians surveyed, 59 (76%) responded, and 35 of the responders (59%) had encountered at least 1 patient with pancreatic cancer during the preceding 12 months. In that subset of physicians, perceived barriers for referral for NCPB were limited appointment availability and need for repeating the procedure.

CONCLUSION

On the basis of this study, referral patterns for NCPB in patients with pancreatic cancer do not seem to be associated with the geographic distance of a patient's residence from a pain control center. Improving appointment availability for NCPB might increase the number of patients offered this technique for control of pain.

Selection of radioimmunoconjugates for the therapy of well-established or micrometastatic colon carcinoma

In order to optimize radioimmunotherapy (RAIT) as a cancer-treatment modality, it is necessary to select the appropriate radionuclide and antibody carrier. We evaluated the therapeutic potential of a single cycle of Mu-9 anti-CSAp monoclonal antibody (MAb) labeled with 3 different radionuclides, 131I, 90Y and 188Re. Intact antibodies and bivalent fragments with different blood clearance kinetics, normal organ distribution and varying tumor accretion and retention are also evaluated. Efficacy of treatment for large and small tumor burden was assessed in nude mice bearing s.c. GW-39 human colonic-carcinoma xenografts or intrapulmonary micrometastatic GW-39 colonies at the maximal tolerated dose of each agent. The magnitude and duration of myelosuppression associated with each radioantibody was considered by monitoring peripheral blood counts, marrow colony-forming unit activity and hematopoietic tissue weight. Radiation-dose estimates were calculated based on the kinetics of antibody accretion and elimination from tumor and normal tissues, and the results were correlated with tumoricidal activity and dose-limiting toxicity results. These studies, therefore, represent a detailed analysis, in a well-defined experimental tumor system, of several parameters (antibody form, radioisotope, tumor size) influencing the overall outcome of RAIT using equitoxic doses. It was found that myelosuppression is the primary dose-limiting toxicity for all radioantibodies except 90Y-F(ab')2, even though the different agents showed varied organ distribution. In a single-cycle treatment schedule of Mu-9 MAb, the 131I-labeled IgG is the radioimmunoconjugate of choice for the treatment of s.c. and intrapulmonary growth of the GW-39 human colonic-carcinoma xenograft in nude mice.

Classification of complex regional pain syndromes. New concepts

A new classification system, termed complex regional pain syndromes types I and II, has been devised to replace the nomenclature of pain disorders previously termed reflex sympathetic dystrophy and causalgia. CRPS type I does not have identifiable major nerve injury, whereas CRPS type II has an identifiable major nerve injury. The classification is based on clinical symptoms and signs without incorporating any mechanistic connotations. These CRPS disorders may have SMP, SIP, or both.

Selection of radioimmunoconjugates for the therapy of well-established or micrometastatic colon carcinoma

In order to optimize radioimmunotherapy (RAIT) as a cancer-treatment modality, it is necessary to select the appropriate radionuclide and antibody carrier. We evaluated the therapeutic potential of a single cycle of Mu-9 anti-CSAp monoclonal antibody (MAb) labeled with 3 different radionuclides, 131I, 90Y and 188Re. Intact antibodies and bivalent fragments with different blood clearance kinetics, normal organ distribution and varying tumor accretion and retention are also evaluated. Efficacy of treatment for large and small tumor burden was assessed in nude mice bearing s.c. GW-39 human colonic-carcinoma xenografts or intrapulmonary micrometastatic GW-39 colonies at the maximal tolerated dose of each agent. The magnitude and duration of myelosuppression associated with each radioantibody was considered by monitoring peripheral blood counts, marrow colony-forming unit activity and hematopoietic tissue weight. Radiation-dose estimates were calculated based on the kinetics of antibody accretion and elimination from tumor and normal tissues, and the results were correlated with tumoricidal activity and dose-limiting toxicity results. These studies, therefore, represent a detailed analysis, in a well-defined experimental tumor system, of several parameters (antibody form, radioisotope, tumor size) influencing the overall outcome of RAIT using equitoxic doses. It was found that myelosuppression is the primary dose-limiting toxicity for all radioantibodies except 90Y-F(ab')2, even though the different agents showed varied organ distribution. In a single-cycle treatment schedule of Mu-9 MAb, the 131I-labeled IgG is the radioimmunoconjugate of choice for the treatment of s.c. and intrapulmonary growth of the GW-39 human colonic-carcinoma xenograft in nude mice.

Halothane reduces myofilament Ca2+ sensitivity during muscarinic receptor stimulation of airway smooth muscle

This study used a beta-escin-permeabilized canine tracheal smooth muscle preparation to test the hypothesis that the volatile anesthetic halothane decreases myofilament Ca2+ sensitivity by inhibiting the membrane receptor-linked second messenger systems that regulate myofilament Ca2+ sensitivity and not by inhibiting Ca(2+)-calmodulin activation of the contractile proteins. Acetylcholine (ACh) caused a GTP-dependent increase in force at constant submaximal cytosolic Ca2+ concentration. ACh, guanosine-5'-O-(3-thiotriphosphate), and the protein kinase C agonist 12,13-phorbol dibutyrate each significantly decreased the concentration of free Ca2+ producing a half-maximal response from 0.77 +/- 0.09 microM (Ca2+ alone) to 0.16 +/- 0.01, 0.19 +/- 0.02, and 0.37 +/- 0.03 microM, respectively, demonstrating an increase in myofilament Ca2+ sensitivity. Halothane (0.92 +/- 0.12 mM) had no effect on the free Ca2+ concentration-response curves generated by Ca2+ alone. However, in the presence of 3 microM ACh plus 10 microM GTP to maximally activate muscarinic receptors, halothane significantly increased the EC50 for free Ca2+ from 0.17 +/- 0.01 microM to 0.38 +/- 0.03 microM. These findings suggest that halothane decreases myofilament Ca2+ sensitivity in beta-escin-permeabilized canine tracheal smooth muscle by inhibiting the membrane receptor-linked second messenger systems that regulate myofilament Ca2+ sensitivity.

Celiac plexus block. Retrocrural computed tomographic anatomy in patients with and without pancreatic cancer

BACKGROUND AND OBJECTIVES

Neurolytic celiac plexus block is often performed for analgesia from pancreatic cancer, but it is not known if the cancer alters the anatomy relevant to the successful performance of retrocrural celiac plexus block.

METHODS

Abdominal computed tomographic scans were used to simulate retrocrural celiac plexus block in patients with and without pancreatic cancer.

RESULTS

Simulated right-sided needle placement in the retrocrural space was more likely to fail in patients with pancreatic cancer than in patients without cancer. Such predicted failure often occurred when the cross-sectional area of the right retrocrural space was less than 1.0 cm2.

CONCLUSIONS

The predicted success of stimulated retrocrural celiac plexus block differed between patients with and without pancreatic cancer. These findings have implications for the performance of celiac plexus block.

Initial studies of monoclonal antibody PAM4 targeting to xenografted orthotopic pancreatic cancer

To resemble the clinical presentation of pancreatic cancer in an animal model more closely, we developed an orthotopic xenograft of CaPan-1 human pancreatic cancer in athymic nude mice. Within 3 weeks after implantation into the body and head of the pancreas, animals had palpable tumors. By 8 weeks, metastases to the liver and spleen were observed, and at 10-14 weeks, ascites formation, with and without seeding of the diaphragm, and jaundice were evident. Thus, this tumor model exhibited many of the most common features of human pancreatic cancer. Radiolabeled monoclonal antibody PAM4 showed specific localization of the primary orthotopic and metastatic tumors. On day 3, PAM4 accumulation within the primary tumor (0.5 g) was 11.3 +/- 5.1% injected dose/g with a localization index of 11.3 +/- 4.0. The estimated tumor:blood radiation dose ratio for PAM4 was 4:1, whereas a nonspecific antibody (Ag8) would provide only 40% of the blood dose to the tumor. Based on these observations, animals bearing 4-week-old orthotopic tumors (estimated volume, 0.25 cm3) were administered either 131I-labeled PAM4, 350 microCi, or nonspecific Ag8, 350 microCi, and compared with an untreated control group. Radiolabeled PAM4 provided a significant (P < 0.001) increase in survival time with less morbidity compared with the untreated control group, whereas nonspecific Ag8 was not significantly different from the control group. These studies provide a rationale for initiating a Phase I clinical study for detection and therapy of pancreatic cancer with PAM4.

Evaluation of a complementarity-determining region-grafted (humanized) anti-carcinoembryonic antigen monoclonal antibody in preclinical and clinical studies

A complementarity-determining region-grafted (humanized) version of MN-14 (hMN-14), a high-affinity, anti-carcinoembryonic antigen (CEA) murine monoclonal antibody (mMAb), was selected from several clones that differed slightly in their framework composition. One clone was selected based on its similar binding affinity to CEA as that observed with mMN-14 MAb and its production yields. Targeting studies, using 131I-labeled humanized MN-14 (hMN-14)/125I-labeled mMN-14 IgG in GW-39 tumor-bearing nude mice, showed excellent tumor uptake and tumor: nontumor ratios, similar to the mMN-14. A pilot clinical imaging trial was initiated to determine the targeting, pharmacokinetics, and dosimetry for 131I-labeled hMN-14 IgG. Nineteen patients with advanced CEA-producing tumors were given 8 to 30 mCi (0.5 to 20.0 mg). Eleven patients also received 131I-labeled mMN-14 IgG for comparison. The biodistribution, tumor targeting, and pharmacokinetic behavior of the hMN-14 was similar to that seen with the mMN-14. The average time required to clear 50% of the radiolabeled hMN-14 from the blood and total body was 32.9 +/- 25.6 h and 109 +/- 73 h, respectively. Patients with elevated plasma CEA (i.e., > 200 ng/ml) had more than 30% of the labeled antibody complexed within 1 h after injection. In some of these patients, increased complexation resulted in enhanced metabolism of the antibody with more rapid clearance from the blood than that seen in patients with lower plasma CEA. The average radiation absorbed dose measured in 20 tumors (average weight, 204 +/- 205 g) in 14 patients was 7.6 +/- 5.3 cGy/mCi. Tumor: nontumor dose ratios were 2.5 +/- 1.6, 9.5 +/- 5.8, and 2.6 +/- 1.8 for the red marrow, total body, and liver, respectively. One patient, with a highly elevated human anti-mouse antibody response from a prior OncoScint study (murine B72.3 IgG), received 3 injections of the hMN-14 without an adverse experience, and showed no evidence of altered biodistribution characteristic of mMAb-human anti-mouse antibody interactions. An antibody response to hMN-14 (HAhMN14) was not detected in patients who received only the hMN-14 (as many as three injections), but in three patients who received two injections of the mMN-14, a HAhMN14 response was detected. With similar, excellent targeting properties as the mMN-14 and the potential for reduced immunogenicity, hMN-14 is an attractive candidate for further clinical imaging and therapy applications.