Novel Treatment with Intraperitoneal MOC31PE Immunotoxin in Colorectal Peritoneal Metastasis: Results From the ImmunoPeCa Phase 1 Trial

BACKGROUND

MOC31PE immunotoxin was developed to rapidly kill cells expressing the tumor-associated epithelial cell adhesion molecule, which is highly expressed in colorectal cancer. Although cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) may offer long-term survival to patients with peritoneal metastasis from colorectal cancer (PM-CRC), most patients experience disease relapse and novel therapeutic options are needed. On this basis, MOC31PE is being developed as a novel therapeutic principle to target PM-CRC.

METHODS

This was a dose-escalating phase I trial to evaluate the safety and toxicity (primary endpoint), pharmacokinetic profile, and neutralizing antibody response (secondary endpoints) upon intraperitoneal administration of MOC31PE in patients with PM-CRC undergoing CRS-HIPEC with Mitomycin C. Fifteen patients received the study drug at four dose levels (3+3+3+6), administered intraperitoneally as a single dose the day after CRS-HIPEC.

RESULTS

No dose-limiting toxicity was observed, and the maximum tolerated dose was not reached. There was negligible systemic absorption of the study drug. Drug concentrations in peritoneal fluid samples were in the cytotoxic range and increased in a dose-dependent manner. MOC31PE recovered from peritoneal cavity retained its cytotoxic activity in cell-based assays. All patients developed neutralizing antibodies.

CONCLUSIONS

Intraperitoneal administration of MOC31PE was safe and well tolerated, and combined with low systemic uptake, MOC31PE seems ideal for local intraperitoneal treatment. The drug will be further evaluated in an ongoing phase II expansion cohort.

Candidate epitopes for measurement of hCG and related molecules: the second ISOBM TD-7 workshop

Participants of the Second International Workshop (WS) on human chorionic gonadotropin (hCG) of the International Society of Oncology and Biomarkers Tissue Differentiation 7 (ISOBM TD-7) have characterized in detail a panel of 69 antibodies (Abs) directed against hCG and hCG-related variants that were submitted by eight companies and research groups. Specificities of the Abs were determined using the First WHO International Reference Reagents for six hCG variants, i.e., hCG, hCGn, hCGβ, hCGβn, hCGβcf, and hCGα, which are calibrated in SI units, and hLH. Molecular epitope localizations were assigned to the ISOBM-mAbs by comparing ISOBM-Ab specificity, sandwich compatibility, and mutual inhibition profiles, to those of 17 reference monoclonal (m)Abs of known molecular epitope specificities. It appeared that 48 Abs recognized hCGβ-, 8 hCGα-, and 13 αβ-heterodimer-specific epitopes. Twenty-seven mAbs were of pan hCG specificity, two thereof with no (<0.1 %; epitope β₁), 12 with low (<1.0 %; epitopes β_2/4), and 13 with high (>>1 %; epitopes β_3/5) hLH cross-reactivity. The majority of hCGβ epitopes recognized were located in two major antigenic domains, one on the peptide chain of the tips of β-sheet loops 1 and 3 (epitopes β_2–6; 27 mAbs) and the second around the cystine knot (e.g., epitopes β₁, β₇, and β₁₀; 9 mAbs). Four mAbs recognized epitopes on hCGβcf-only (e.g., epitopes β₁₁ and β₁₃) and six mAbs epitopes on the remote hCGβ-carboxyl-terminal peptide (epitopes β₈ and β₉ corresponding to amino acids 135–144 and 111–116, respectively). For routine diagnostic measurements, methods are used that either detect hCG-only, hCGβ-only, or hCG together with hCGβ or hCG together with hCGβ and hCGβcf. Sandwich assays that measure hCG plus hCGβ and eventually hCGβcf should recognize the protein backbone of the analytes preferably on an equimolar basis, should not cross-react with hLH and not be susceptible to blunting of signal by nonmeasured variants like hCGβcf. Such assays can be constructed using pairs of mAbs directed against the cystine knot-associated epitope β₁ (Asp10, Asp60, and Gln89) in combination with epitopes β₂ or β₄ located at the top of β-sheet loops 1 + 3 of hCGβ involving aa hCGβ20-25 + 68-77. In summary, the results of the First and Second ISOBM TD-7 WSs on hCG provide the basis for harmonization of specificities and epitopes of mAbs to be used in multifunctional and selective diagnostic hCG methods for different clinical purposes.

TD-11 workshop report: characterization of monoclonal antibodies to S100 proteins

Fourteen monoclonal antibodies with specificity against native or recombinant antigens within the S100 family were investigated with regard to immunoreactivity. The specificities of the antibodies were studied using ELISA tests, Western blotting epitope mapping using competitive assays, and QCM technology. The mimotopes of antibodies against S100A4 were determined by random peptide phage display libraries. Antibody specificity was also tested by IHC and pair combinations evaluated for construction of immunoradiometric assays for S100B. Out of the 14 antibodies included in this report eight demonstrated specificity to S100B, namely MAbs 4E3, 4D2, S23, S53, 6G1, S21, S36, and 8B10. This reactivity could be classified into four different epitope groups using competing studies. Several of these MAbs did display minor reactivity to other S100 proteins when they were presented in denatured form. Only one of the antibodies, MAb 3B10, displayed preferential reactivity to S100A1; however, it also showed partial cross-reactivity with S100A10 and S100A13. Three antibodies, MAbs 20.1, 22.3, and S195, were specific for recombinant S100A4 in solution. Western blot revealed that MAb 20.1 and 22.3 recognized linear epitopes of S100A4, while MAb S195 reacted with a conformational dependent epitope. Surprisingly, MAb 14B3 did not demonstrate any reactivity to the panel of antigens used in this study.

Human heterophilic antibodies display specificity for murine IgG subclasses

OBJECTIVES

The study investigated heterophilic antibodies: the human immunoglobulin classes involved and their specificity for different murine IgG subclasses.

DESIGN AND METHODS

Using immunofluorometric assays for human IgA, IgM and IgG binding murine IgG1, we analyzed 173 samples displaying positive interference and 97 negative control samples from a previous study. We also set up assays for heterophilic antibody interference using Mabs from different murine IgG subclasses. Three Mabs each of murine IgG1, IgG2a and IgG2b subclasses, one murine IgG3 Mab and one rat Mab were used.

RESULTS

Elevated levels of human murine IgG1-binding immunoglobulins of IgM class only were found in 40% of interference-positive samples, human IgG only in 1.7%, and human IgA only in 2.3% of the samples. Both elevated human IgG and IgM classes were found in 3.5% of the samples, IgA and IgM in 4.0%, and finally, all three immunoglobulin classes in 1.7% of the samples. Eighty percent of interference positive samples showed heterophilic assay interference for at least one murine IgG1 Mab, 35% for IgG2a, 66% for IgG2b, 52% for IgG3a and 17% for the rat Mab.

CONCLUSIONS

Heterophilic antibody interference is mainly caused by IgM class human antibodies with a marked murine IgG subclass specificity. Combining assay antibodies from different murine IgG subclasses may reduce interference in immunoassays.

Testing and validating a homogeneous immunometric assay for interference

We analyzed 95 sera, demonstrating interference in a previous study, with the Kryptor homogeneous time-resolved fluorescence resonance energy transfer carcinoembryonic antigen (CEA) immunoassay (Brahms AG, Berlin, Germany). Only one serum differed, i.e., 6.0 μg/l for Kryptor vs. 13.3 μg/l for a microtiter plate in-house immunofluorometric assay (IFMA), using both aggregated mouse immunoglobulins as blocker and capture monoclonal antibody (Mab) F(ab′)

Kryptor-CEA assay results thus agreed with our inhouse CEA assay results, showing no interference. As the Kryptor-CEA assay antibodies were sensitive to interference and the Kryptor-CEA assay buffer did not reduce interference as efficiently as our in-house assay buffer, the Kryptor-CEA assay format was crucial for the absence of interference.

Epitopes on CA 125 from cervical mucus and ascites fluid and characterization of six new antibodies. Third report from the ISOBM TD-1 workshop

CA 125 is found in body fluids in a variety of molecular weight forms. The largest species are found in normal abdominal fluid and cervical mucus. The present study therefore incorporated CA 125 derived from these sources as well as ascites fluid to investigate if the source of CA 125 influenced epitope characterization. Ascites-derived CA 125 varied in size from about 190 to about 2,700 kD. Cervical mucus-derived CA 125 treated with ultrasound changed its apparent size from more than 20,000 to 700 kD. Epitope mapping of antibodies was not grossly influenced by the size or source of CA 125 used as target. However, low-molecular-weight CA 125, i.e. ascites fractions CA 17/E, CA 17/F and CA 10/7, did show differences in certain assay combinations and cross-inhibition patterns which probably can be explained by steric effects due to the smaller size compared with the most abundant forms of CA 125 present in serum and other body fluids. The specificity of six new monoclonal antibodies to CA 125 was tested by cross-inhibition and immunometric assay combinations and compared to reference antibodies. One antibody, X306, belonged to the OC125-like antibodies. Four antibodies, X52, X75, X325 and VK8, were M11-like. The sixth antibody, 7C12, reacted with an epitope which was difficult to define. This antibody was inhibited by M11-like antibodies and OV197. However, used as an inhibitor, 7C12 inhibited only itself. We grouped it as an OV197-like antibody, but clearly different from OV197. The topography of epitopes was studied by analyzing all antibody pairs in immunoradiometric assays. These results confirmed the grouping of antibodies described above and are in accordance with previous findings that the highest signal is obtained using an OC125-like antibody or OV197 on the solid phase and an M11-like antibody as tracer. The composition of the sample in terms of high- and low-molecular-weight species of CA 125 was measured, with different responses depending on the antibody pair used. This might be one reason for discrepancies between assay results for CA 125 using different assays.

Immunometric assay interference: incidence and prevention

BACKGROUND

The primary aim of the study was to reduce interference in an in-house two-site, two-step immunometric assay.

METHODS

In the running laboratory routine, 11 261 samples were tested with a carcinoembryonic antigen (CEA) assay with bovine immunoglobulin but no murine immunoglobulins in the buffer, in parallel to our routine CEA assay, using 15 mg/L heat-treated nonspecific murine immunoglobulin (MAK33) in the buffer and with the Fc fragments removed from the capture antibody.

RESULTS

The frequency of interference was estimated to be 4.0% (95% confidence interval, 3.3-4.7%). The addition of 15 mg/L native MAK33 had little effect (frequency, 3.9%; 95% confidence interval, 3.2-4.6%), whereas adding 15 mg/L heat-treated MAK33 reduced interference to 0.86% (0.61-1.12%), and adding 50 mg/L reduced it further to 0.06% (0-0.13%). Removing the Fc fragments by itself reduced interference to 0.10% (0.02-0.19%). There were no statistically significant differences for age (P <0.23) or gender (P <0.40) between patients with interference (n = 210) and a randomly selected interference-negative control group (n = 186). Interference was not constant in patients: 15 of 25 individuals positive for interference and with four or more samples screened for interference had an interference-negative sample either before or after the peak of interference.

CONCLUSIONS

In a two-site, two-step immunometric assay using mouse monoclonal antibodies, use of heat-treated nonspecific murine immunoglobulin in the buffer or removal of the Fc fragment from the capture antibody could improve performance.

Immunometric Assay Interference

Background: The primary aim of the study was to reduce interference in an in-house two-site, two-step immunometric assay.

Methods: In the running laboratory routine, 11 261 samples were tested with a carcinoembryonic antigen (CEA) assay with bovine immunoglobulin but no murine immunoglobulins in the buffer, in parallel to our routine CEA assay, using 15 mg/L heat-treated nonspecific murine immunoglobulin (MAK33) in the buffer and with the Fc fragments removed from the capture antibody.

Results: The frequency of interference was estimated to be 4.0% (95% confidence interval, 3.3–4.7%). The addition of 15 mg/L native MAK33 had little effect (frequency, 3.9%; 95% confidence interval, 3.2–4.6%), whereas adding 15 mg/L heat-treated MAK33 reduced interference to 0.86% (0.61–1.12%), and adding 50 mg/L reduced it further to 0.06% (0–0.13%). Removing the Fc fragments by itself reduced interference to 0.10% (0.02–0.19%). There were no statistically significant differences for age (P &lt;0.23) or gender (P &lt;0.40) between patients with interference (n = 210) and a randomly selected interference-negative control group (n = 186). Interference was not constant in patients: 15 of 25 individuals positive for interference and with four or more samples screened for interference had an interference-negative sample either before or after the peak of interference.

Conclusions: In a two-site, two-step immunometric assay using mouse monoclonal antibodies, use of heat-treated nonspecific murine immunoglobulin in the buffer or removal of the Fc fragment from the capture antibody could improve performance.

Transoesophageal echocardiographic monitoring during paediatric cardiac surgery: obtainable information and feasibility in 532 children

BACKGROUND

We hypothesized that transoesophageal echocardiography (TOE) performed by the anaesthesiologists would be beneficial for monitoring purposes during paediatric cardiac surgery. We present the results for the first 5 years in 532 consecutive children.

METHODS

The probe was successfully inserted in 99% of cases and remained in the oesophagus for 211 min on average (range 10-555 min).

RESULTS

Insignificant valve leak, single- or biventricular failure and volume depletion were the most common new findings due to TOE. Changes in inotropic strategy and volume replacement were the most frequent interventions. In 45% of the cases, new information was disclosed and, in a total of 8% of cases, decisive information was provided. Except for tracheal extubation in one child who was uneventfully reintubated, no severe complications were identified.

CONCLUSIONS

These data stress the safety and ease of performing TOE in children undergoing cardiac surgery. There is evidence for benefit from TOE findings to potentially enhance the therapeutic basis.

Neurohormonal activation late after cavopulmonary connection

OBJECTIVE

To determine whether patients with cavopulmonary connection have higher levels of vasoactive/water-salt regulating hormones and if so, whether hormone levels are related to postoperative haemodynamics and postoperative follow up.

DESIGN

Cross sectional study.

SETTING

University hospital.

PATIENTS

20 patients (New York Heart Association functional class I-II), mean age 11 years (range 4 to 22), were studied at a mean of 2 years (0.5 to 6) after a total cavopulmonary connection (TCPC, n = 12) or a bidirectional Glenn anastomosis (BDG, n = 8).

INTERVENTIONS

Cardiac catheterisation was performed and blood samples were drawn. Control blood samples were drawn from 33 healthy children, mean age 12 years (6 to 16).

MAIN OUTCOME MEASURES

Plasma levels of angiotensin II, renin, aldosterone, arginine, vasopressin, atrial natriuretic factor (ANF), brain natriuretic peptide (BNP).

RESULTS

All neurohormones were significantly increased in both TCPC and BDG patients (p < 0. 05), with a fourfold increase in angiotensin II, renin, and aldosterone, and a twofold increase in vasopressin, ANF, and BNP (compared with healthy controls). There was no correlation between haemodynamic variables and hormone levels. Angiotensin II and renin were inversely correlated with time to follow up. All subjects over 15 years (n = 5) had normal neurohormonal levels.

CONCLUSIONS

Neurohormones were raised for years after successful cavopulmonary operations but lower levels were observed with time on follow up. This supports the hypothesis that neurohormonal activation is primarily related to altered postoperative physiology and that adaptation takes place over time.

Pediatric multiplane transesophageal echocardiography in congenital heart disease: new possibilities with a miniaturized probe

In recent years, transducers for multiplane Doppler echocardiography have demonstrated their superior imaging performance in adult patients. To date, the size of these probes has limited their use in pediatric patients. In this article, we report our initial experience with a recently developed miniaturized transducer with all conventional imaging and Doppler modalities. The study focused primarily on imaging performance by comparing standard biplane images with those obtained in oblique planes. The investigations were carried out intraoperatively or during interventional catheterization in patients with congenital heart disease. We observed no complications in a study population of 15 children (weight range of 5 to 63 kg and an age range of 96 days to 11 years). The probe was easy to handle and provided excellent images. Additional information was obtained in several cases and documentation of clinical findings was easier because an optimal image plane almost always could be displayed. We concluded that pediatric multiplane Doppler echocardiography has considerably improved investigative performance compared with the conventional monoplane or biplane studies normally available for this age group. In neonates, however, investigation with the multiplane technique is limited by the size of the patient.

Comparison of intravenous and topical lidocaine as a suppressant of coughing after bronchoscopy during general anesthesia

Twenty-four consecutive patients scheduled for fiberbronchoscopy were randomized to receive double-blind either intravenous (1.5 mg/kg) or laryngotracheal (3 mg/kg) lidocaine to evaluate the influence on post-bronchoscopic laryngospasm, pain in the throat and coughing. Plasma lidocaine concentrations were analyzed 5, 15, 30 and 60 min after administration. None of the patients demonstrated laryngospasm or pain in the throat during the first hour after bronchoscopy. Patients receiving topical lidocaine coughed significantly more than patients receiving intravenous lidocaine, with a median number of coughs of 20 compared to 4, during the first hour (P less than 0.01). The plasma lidocaine concentrations were significantly higher after intravenous than after topical administration (P less than 0.001). After intravenous administration the plasma lidocaine concentrations exceeded the accepted level for potential toxicity in five out of 11 patients, but none of the patients developed toxic symptoms and no side-effects were observed.

Spinal analgesia with plain 0.5% bupivacaine administered at spinal interspace L2-3 or L4-5

Forty patients (age range 60-79 yr) undergoing transurethral surgery were allocated randomly to receive 0.5% plain bupivacaine 4 ml at the L2-3 (n = 20) or L4-5 (n = 20) space. The solution was injected over 30 s with the patient in the sitting position. The patient was kept sitting for 2 min, then placed supine and, 5 min later, placed in the lithotomy position. No significant differences were found in onset time, extent and duration of analgesia or duration of motor block.

Stress response and platelet function in minor surgery during epidural bupivacaine and general anaesthesia: effect of epidural morphine addition

In a randomized study, thirty patients submitted to transarthroscopic meniscectomy were allocated to general or epidural anaesthesia with or without epidural morphine. Threshold concentration of collagen for platelet aggregation did not differ between the groups, but showed a similar pattern of increase, which was significant in the general anaesthesia group. Collagen-induced thromboxane-B2 synthesis was significantly lower in the epidural anaesthesia groups compared with the general anaesthesia group, and the addition of morphine caused a significant fall in thromboxane-B2 synthesis. The mean serum cortisol concentration increased in the general anaesthesia group, and decreased in the epidural groups. The difference between the groups was significant. Epidural morphine administration significantly decreased serum cortisol. During operation a thigh tourniquet was used. The removal of the tourniquet did not influence any of the measured variables. It can be concluded that the adrenocortical system is activated during general and inhibited during epidural anaesthesia. The addition of morphine during epidural anaesthesia further decreases the activity of the adrenocortical system, and the combined regime has an inhibiting effect on platelet function.

[Clinical aspects of spinal anesthesia administered using 0.5% isobar bupivacaine (Maracine) at the L2/L3 or L4/L5 level]

The effect of employing different interspaces for lumbar puncture during spinal anaesthesia was evaluated in 40 patients receiving 4 ml of 0.5% plain bupivacaine at level L2/L3 or L4/L5. No differences were observed in onset, spread or duration of analgesia. Furthermore, we found that only 80% of the patients, independently of the interspace used, had a cephalad spread to T8 and conclude that spinal anaesthesia using plain bupivacaine is not ideal for supraumbilical surgery.

Plain bupivacaine: 0.5% or 0.25% for spinal analgesia?

Plain 0.5% bupivacaine 3 ml was compared with plain 0.25% bupivacaine 6 ml for spinal anaesthesia during transurethral surgery in 40 patients. The solutions were injected over 30 s at the L3/4 space with the patient in the sitting position. The patient was kept sitting for 2 min, supine for 5 min and then placed in the lithotomy position. No significant differences were found in onset time, extent of cephalad spread, duration of sensory or motor blockade, or side effects. The use of a 0.5% plain solution of bupivacaine did not appear to confer any advantage over the 0.25% solution.

Combination high dose amrinone and dopamine in the management of moribund cardiogenic shock after open heart surgery

Two patients who suffered severe cardiogenic shock after open-heart surgery were successfully resuscitated with high doses of amrinone and dopamine. Both patients had required cardiopulmonary resuscitation and neither was responsive to more conventional mechanical and pharmacologic intervention. Neither patient suffered any serious side effects and both were eventually discharged from the hospital in good condition. These two case reports suggest the potential for using higher than previously reported doses of amrinone in combination with dopamine for the successful treatment of moribund cardiogenic shock in the post open-heart surgical patient. Further studies are needed to assess whether this high-dose drug combination will be successful in patients who present with severe cardiogenic shock unrelated to the post open-heart surgical setting.

Verapamil induced increment of oxygen extraction in the arteriosclerotic limb

The acute effect of intravenously administered verapamil (0.08 mg X kg-1 body weight, mean dose 5.1 +/- 0.7 mg) on oxygen exchange and arterial blood flow (measured electromagnetically) of the lower limb was studied during reconstructive arterial surgery in 17 patients with obliterative arterial disease of the lower limbs. Verapamil increased oxygen extraction in the diseased leg by 12% (from a median value of 28.3 to 31.6 ml X litre-1, p less than 0.01) whereas it had no effect on arterial blood flow. The increment of oxygen extraction after drug administration correlated negatively with the walking distance of the patients (r = 0.69, p less than 0.01). Systolic and diastolic blood pressure decreased significantly by 10% and 6%, respectively, whereas heart rate remained unchanged after the administration of verapamil. The results suggest that verapamil might be beneficial in the treatment of patients with intermittent claudication, despite the fact that no vasodilatation was seen after the drug.