Immunoscintigraphy with 99mTc labelled F(ab')2 fragments of an anti melanoma monoclonal antibody (225.28S) in patients with metastatic malignant melanoma

Theranostic impact of NG2/CSPG4 proteoglycan in cancer

NG2/CSPG4 is an unusual cell-membrane integral proteoglycan widely recognized to be a prognostic factor, a valuable tool for ex vivo and non-invasive molecular diagnostics and, by virtue of its tight association with malignancy, a tantalizing therapeutic target in several tumour types. Although the biology behind its involvement in cancer progression needs to be better understood, implementation of NG2/CSPG4 in the routine clinical practice is attainable and has the potential to contribute to an improved individualized management of cancer patients. In this context, its polymorphic nature seems to be particularly valuable in the effort to standardize informative diagnostic procedures and consolidate forcible immunotherapeutic treatment strategies. We discuss here the underpinnings for this potential and highlight the benefits of taking advantage of the intra-tumour and inter-patient variability in the regulation of NG2/CSPG4 expression. We envision that NG2/CSPG4 may effectively be exploited in therapeutic interventions aimed at averting resistance to target therapy agents and at interfering with secondary lesion formation and/or tumour recurrence.

Laboratory tests and imaging studies in patients with cutaneous malignant melanoma

Laboratory tests and imaging studies are often ordered for asymptomatic patients with malignant melanomas (MMs) in an effort to detect subclinical metastatic disease. However, their sensitivity and specificity for detecting cryptic metastases are not well established. A review of the literature on laboratory tests and imaging studies for MM metastases was undertaken to address the usefulness of such investigations in asymptomatic patients with MM in AJCC (American Joint Committee on Cancer system of classification) stages I, II, and III. A review of the pertinent literature since 1966 was conducted through MEDLINE, Medica, and Cancerlit. Laboratory tests and imaging studies revealed occult MM metastases in only a small number of the thousands of reported patients with putative AJCC stage I, II, and III MM. However, for those diagnosed with limited metastases, surgical removal with or without immunotherapy, chemotherapy, or radiotherapy can lead to long-term remissions in some patients. For patients with asymptomatic AJCC stage I or II disease, chest roentgenograms (CXR) and blood lactic dehydrogenase (LDH) levels may be obtained at low cost and prove to be of benefit if metastases are identified. For patients with AJCC stage III disease, computed tomographic (CT) scans of the thorax, abdomen, and pelvis (especially when the primary cutaneous site of the melanoma is below the waist) may be considered for detecting metastatic MM. Other tests, such as magnetic resonance imaging (MRI) scans of the brain, may be ordered based on symptoms or physical findings. In the future, technologically improved techniques and newer methods may prove cost-effective for detecting treatable asymptomatic MM metastases. Furthermore, improvement in treatments will also influence the indications for the search for occult MM metastases. At this time there is a need for an international consensus conference on laboratory tests and imaging studies for occult melanoma metastases.

Primary malignant melanoma of the oesophagus with a left atrial metastasis

A 75 year old man with an eight month history of dysphagia and weight loss underwent pericardiocentesis for a massive pericardial effusion. The echocardiogram showed a mass in the left atrium, and computed tomography also showed distal oesophageal narrowing, which was found to be due to a malignant melanoma. The left atrial mass, investigated by immunoscintigraphy with technetium-99m labelled monoclonal antibody, was diagnosed as metastatic melanoma. This represents a rare case of primary oesophageal melanoma with left atrial metastasis.

Radioimmunodetection and radioimmunotherapy of malignant melanoma. A review

Radioimmunodetection utilizing monoclonal antibodies to various melanoma-associated surface antigens has been studied by several investigators during the past ten years. In the early trials, antibodies were labeled with 131I or 111In, but now 99mTc is almost exclusively used because of its more favorable energy for gamma camera imaging. Excellent specificity has been achieved in most studies, whereas sensitivity has been less good. In a recent European multicenter study on 493 patients sensitivity was 79% and specificity 96%. In this largest study on melanoma so far performed many previously unknown metastatic deposits were identified indicating that radioimmunodetection has a role in the management of metastatic disease. The clinical utility of immunoscintigraphy in localization of regional lymph node metastases has been documented in several investigations in recent years, indicating that this method can be used in the preoperative evaluation of patients. Radioimmunodetection has also been successfully used in the differential diagnosis of ocular lesions. However, conclusive evidence of improved patient outcome resulting from the earlier detection of melanoma lesions by immunoscintigraphy is still lacking. Anti-melanoma antibodies labeled with alpha- and beta-emitting isotopes are potential therapeutic agents, but so far there is little clinical experience with radioimmunotherapy of metastatic melanoma.

European multicentre study on melanoma immunoscintigraphy by means of 99mTc-labelled monoclonal antibody fragments. The European Multicentre Study Group

A total of 493 melanoma patients were investigated by 20 European nuclear medicine departments by means of the same 99mTc-labelled immunoradiopharmaceutical and the same immunoscintigraphy (ISG) protocol. (i) No chemical or clinical toxicity was detected during or following the studies. (ii) Positive results were obtained in 287/363 (79%) patients (321 carrying known lesions and 42 carrying previously occult lesions): in 231 (80%) of them, 402/402 lesions were imaged; in the remaining 56 ISG-positive patients, 108/204 lesions were imaged; in 76 patients 0/122 lesions were imaged. (iii) The fraction of melanoma lesions visualized by ISG was 510/728 (70.1%); 605 of these lesions were already documented at the time of the study, and 123 were previously occult. (iv) A total of 218 documented melanoma lesions (30%) were not visualized by ISG in 132 patients: about 70% of the ISG-negative lesions were of small size (less than 2 cm diameter). (v) The melanoma nature of 69/123 previously occult lesions was confirmed by clinical criteria and/or additional investigations in follow-up studies. The results obtained in this study are similar to those obtained in the Italian Multicentre Study which had previously been carried out with 258 melanoma patients.

Effect of in vivo administration of interferon gamma on expression of MHC products and tumour associated antigens in patients with metastatic melanoma

IFN-gamma is an effective inducer of MHC class II antigen expression in cell lines of malignant melanoma. To investigate the possibility that IFN-gamma may increase MHC class I and II and melanoma tumour associated antigens in vivo, immunohistochemical analyses of biopsies from six patients with metastatic disease undergoing IFN-gamma treatment were performed. Before IFN-gamma treatment, the melanomas were class I positive and class II negative. After treatment, class I expression was neither enhanced nor class II expression induced in any tissue sample regardless of biopsy time or dose of IFN-gamma. TAA was similarly unchanged. However, in one of the six patients a primary cell line was established and IFN-gamma induced expression of MHC products. The possible reasons for lack of MHC induction are discussed, although qualitative changes in antigen expression cannot be excluded on the basis of qualitative immunocytochemical techniques alone.

Radiolabeled monoclonal antibodies in the diagnosis and treatment of malignant melanoma

The use of antibodies directed against tumors has found increasing usefulness after the discovery by Kohler and Milstein of hybridoma technology, which made it possible to obtain monoclonal antibody (MoAb) that reacted specifically against a particular epitope on a particular antigen site. Relative tumor specificity and a lack of significant toxicity, together with the ability to link radionuclides (both halogens and metals) without significant deterioration of biologic behavioral characteristics such as immunoreactivity, have enabled widespread use of radiolabeled MoAbs in several malignancies, including and especially malignant melanoma. There is a significant body of data indicating that radiolabeled MoAbs directed against melanoma-associated antigens have an important role in the detection and therapy of metastatic malignant melanoma. Detection of visceral disease, while currently suboptimal, will in the future improve with optimization of SPECT imaging using 99mTc-labeled MoAb Fab fragments. This may result in an attenuated or absent antimouse response, especially after one injection, unless of course coinfused with either specific and/or nonspecific intact immunoglobulin (Ig). Radiolabeled fragments play an important role in radioimmunotherapy in metastatic melanoma. This role may be enhanced by the development of newer chelating agents that will decrease nonspecific hepatic uptake of radionuclide, enabling the use of beta-emitting radiometals such as 90Y. The recent report demonstrating diminished hepatic uptake of 99mTc-labeled anti-high molecular weight antigen (HMWA) Fab shows promise, since the same labeling technique can be used to deliver radiotherapeutic agents such as 186Re, which may be labeled to MoAb with methods similar to those used for 99mTc. Creation of single-chain MoAb determinants, chimera, and human MoAb will obviate the human immune response to foreign proteins that are currently in use and enable multiple administrations of tumor-toxic quantities of radiolabeled MoAbs.

A comparative study of the relative sensitivity and specificity of radiolabelled monoclonal antibody and computerised tomography in the detection of sites of disease in human malignant melanoma

A monoclonal antibody raised against the high molecular weight melanoma antigen was labelled with indium-111 and injected intravenously into 25 patients with malignant melanoma. The results obtained from images at 24 and 96 h post i.v. administration of the antibody were compared with results obtained from computerised tomography studies with regard to detection of previously unrecognised sites of metastatic disease and apparent false positive localisation. Detailed study of the patients' clinical condition and detection rates using the two methods suggest that both methods detect approximately 80% of clinically and pathologically confirmed metastases. Of 62 known metastases, the antibody detected 50 (81%), with 17 false positive results. False negatives were most common in the lung. In eight patients the two methods were considered of equal value, in 10 the monoclonal gave a greater amount of clinically relevant information, and in seven the CT was superior. In three patients clinically significant metastatic lesions were detected by the radiolabelled monoclonal and had not been previously recognised either by CT scanning or on clinical grounds. No patients had any adverse reaction to the antibody and in the course of our study the dose of antibody was reduced from 20 mg to 200 micrograms with no apparent loss of sensitivity. In at least two patients uptake of the labelled monoclonal into tumour sites would have been adequate for effective targeted radiotherapy.

Immunoscintigraphy and pharmacokinetics of indium-111-labeled ZME-018 monoclonal antibody in patients with malignant melanoma

Immunoscintigraphic and pharmacokinetic characteristics of 111In-labeled ZME-018 monoclonal antibody were examined in 8 patients with malignant melanoma. Each patient received a single intravenous infusion of 20 mg of ZME-018, coupled to 3 mCi of 111In without any acute toxicity. Scintigrams were taken 1, 3, and 6 days after the administration, and blood and urine samples were also taken frequently. Rapid clearance of some radioactivity was seen in early urine samples in the form of 111In DTPA, but after 1 day, urinary excretion of radioactivity was slow and steady, with an average of 2.5% of the injected dose excreted per day. The scans demonstrated that there was blood retention of radioactivity in the heart and great vessels 1 day after infusion and considerable clearance from the blood pool occurred by 3 days. However, 111In was deposited in the liver, spleen and bone for up to 6 days. The optimal time for imaging appeared to be at 3 days. Nineteen out of 26 known lesions or 6 out of 8 patients were positive. There were 21 lesions detected that were not suspected during the work-up the patient. Five patients developed human anti-mouse antibody in the serum by 3 weeks. These results suggest that immunoscintigraphy with 111In-labeled ZME-018 antibody is safe and useful for the detection of metastatic lesions in a selected group of patients with malignant melanoma.