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.