Prospects for the management of non-small-cell carcinoma of the lung with monoclonal antibodies

Two messenger RNAs and five isoforms for Po66-CBP, a galectin-8 homolog in a human lung carcinoma cell line

Galectins are animal proteins which specifically bind beta-D-galactoside residues and their specific cellular function is not yet clearly established. However, these proteins seem to play a role in neoplastic transformations. Po66 is a murine monoclonal antibody directed against a protein from human lung carcinoma, Po66 Carbohydrate-Binding-Protein (Po66-CBP), which belongs to the galectin-8 family. Our results show that the Po66-CBP gene generates five transcripts by alternative splicing, which could give rise to five proteins: two proteins belong to the tandemly repeated galectin family and three belong to the single carbohydrate recognition domain galectins. All these proteins are encoded by a unique gene located in 1q42. Experiments carried out by reverse transcriptase-polymerase chain reaction show that the levels of expression of these five galectin-8 isoforms are variable during the culture time in SK-MES-1, a human lung squamous carcinoma cell line. Cancer Genome Anatomy Project database analysis confirms the presence of Po66-CBP in lung cancer and its absence in healthy lung.

Intraoperative detection of lung cancer by octreotide labeled to Indium-111

The contribution of radio surgery (RGS) using octreotide labeled with Indium-111 (In111) has been studied for surgical treatment of lung cancer. Thirteen patients were administered 111 Mbq of In111 octreotide intravenously. Scintigraphic images were preoperatively taken at 4, 24, and 48 hours after the tracer injection. Pulmonary resection and intraoperative evaluation by RGS technique were then performed to set the section limits. Histological staining of all the resected specimens and resection margins were assessed and their results were used as a confirmation of the RGS intraoperative findings. RGS is a simple method that can help the surgeon in the intraoperative assessment of bronchial, parenchymal, and parietal resection margins. Further research is needed to verify whether this method also may be useful in the intraoperative definition of the extent of mediastinal lymph node dissection.

Pulmonary Tc-99m tetrofosmin imaging: clinical experience with detecting malignant lesions and monitoring response to therapy

The authors prospectively investigated the uptake and kinetics of Tc-99m tetrofosmin (Tetro) in benign and malignant lung lesions and the effect of radiotherapy, chemotherapy, or both on Tc-99m Tetro uptake in malignant lung tumors. Dynamic and planar Tetro imaging were performed in 45 patients with pulmonary lesions during a period of 28 months (34 untreated malignant tumors, 11 benign lesions). Tetro uptake was visibly increased in 26 of 34 malignant tumors, with a mean lesion to contralateral normal tissue ratio of 1.44 +/- 0.29 and a tumor washout rate of 28.4 +/- 6.6% 30 minutes after injection. In 3 of 11 benign lesions, Tetro uptake was observed. Of the 26 patients with malignant tumors and positive Tetro uptake, nine had repeated imaging 6 to 8 weeks after therapy. The patients were treated with radiotherapy, chemotherapy, or both. Reduction in radiological tumor size was used as the clinical response parameter. In five of nine patients, the course of Tetro uptake in follow-up imaging was in accordance with that of radiological tumor size. Two of four remaining patients had only slight discordance between the alteration of Tetro uptake and radiological tumor size. The sensitivity of Tetro to detect malignant lung lesions in our patients was 77%. The specificity and accuracy of the method were 73% and 76%, respectively. Tetro has limited diagnostic value in detecting lung cancer. It may be useful to monitor the response to therapy in malignant lung tumors with initial tracer uptake. Broader trials on this matter are needed for further clarification.

Alternatives to chemotherapy and radiotherapy as adjuvant treatment for lung cancer

Because adjuvant chemotherapy has resulted in only modest prolongation of survival for patients with lung cancer, investigators have turned to the evaluation of alternative treatment strategies for this patient population. Immunotherapy with Bacillus Calmette Guerin, Corynebacterium parvum, and levamisole has been evaluated in several prospective randomized trials, and no study has shown a statistically significant difference in overall survival. Interferon has been evaluated in three trials of adjuvant therapy after response to chemotherapy for small cell lung cancer. Different interferon preparations were used, but none of the trials showed a significant prolongation of survival. The retinoids have been evaluated as adjuvant treatment after complete resection of stage IN-SCLC. One trial showed a reduction in second primary tumors, and in particular, tumors to tobacco smoking in patients treated with retinyl palmitate. A second trial using 13-cis retinoic acid is ongoing in North America. In the last decade, several inhibitors of angiogenesis have been identified, and they are now beginning to be evaluated in the clinical setting. The National Cancer Institute of Canada Clinical Trials Group and the European Organization for Research and Treatment of Cancer have initiated a study of adjuvant marimastat, a metalloproteinase inhibitor, for patients who have responded to induction chemotherapy for small cell lung cancer. This is the first adjuvant antiangiogenesis factor trial to be initiated for any tumor type. Other investigational agents which are currently undergoing Phase I and Phase II testing include monoclonal antibodies which may inhibit tumour cell growth by binding to growth factors, or which may be conjugated to toxins or chemotherapeutic agents which result in tumour cell death. In the last decade, we have witnessed an explosion in our knowledge and understanding of the regulation of normal and neoplastic cell growth at the molecular level. It remains only speculative at this time as to whether manipulation of abnormal genes in malignant cells will be clinically possible, and whether treatment of this sort may be applied in an adjuvant setting.

Radioimmunodetection of malignant solid tumours

An increased clinical utility of radiolabelled monoclonal antibodies (MoAb), recognizing a variety of different antigens expressed preferentially in malignant tissue, for localizing primary, metastatic and recurrent cancer has been documented in many recent investigations. This review focuses on both basic and practical aspects of radioimmunodetection in oncology and is a status report on the performance and limitations of radiolabelled antibody procedures currently applied to the clinical detection of malignant solid tumours. At this time clinically validated radioimmunodetection methods are available for colorectal, ovarian, breast, lung, thyroid medullary, and head and neck carcinoma, and melanoma. Recent advances in humanization of MoAb significantly improve the prospects of effective antibody-guided radiotherapy in the near future.

Serum tumor markers in non-small cell lung cancer. A comparative analysis

BACKGROUND

The role of serum tumor markers in non-small cell lung cancer (NSCLC) remains undefined. New proposed markers have seldom been rigorously compared with existing standards. The authors prospectively compared the performance of three new monoclonal antibodies (MoAb) (5E8, 5C7, and 1F10) with the established serum markers carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCC).

METHODS

The cohort consisted of 45 consecutive out-patients with newly diagnosed NSCLC: Control subjects were 38 outpatients with non-neoplastic chronic pulmonary diseases. Blood from each patient and control subject was assayed for all five tumor markers. An enzyme-linked immunosorbent assay (ELISA) was used to determine 5E8, 5C7, and 1F10 reactivity. Commercially available kits were used to measure SCC by radioimmunoassay and CEA by ELISA: Individual and combinations of tumor markers were compared in terms of sensitivity, specificity, and accuracy for NSCLC diagnosis.

RESULTS

5E8 plus 5C7 plus 1F10 significantly surpassed SCC plus CEA in terms of sensitivity (P < 0.05) and proved the most accurate marker combination. Among single markers, 5E8 was most specific, 5C7 most sensitive, and 5C7 and 1F10 each most accurate, but differences from CEA alone were not significant. Subgroup analysis by histologic type and stage demonstrated similar findings, and marker combinations yielded little additional diagnostic benefit.

CONCLUSIONS

5E8, 5C7, and 1F10 performed marginally better than did CEA and SCC in patients with newly diagnosed NSCLC: Many limitations apply in defining a clinical niche for these tumor markers in NSCLC, although 5E8, 5C7, and 1F10 previously have demonstrated a modest prognostic value. An adjunctive role in a few specific clinical contexts remains possible.

Recent developments in radioimmunotherapy

With the advent of monoclonal antibody techniques, there has been renewed interest in RIT as a treatment modality in patients with a variety of tumour types. There has been a considerable research effort to increase understanding of the scientific basis of such therapy at all levels. Antibody, chelator and radioisotope factors are all the subject of research aimed at producing a potent effector system capable of maximal target cell kill with acceptable normal tissue toxicity. Improved knowledge of the host and tumour factors which limit access to the target cell offers the possibility of optimizing targeting and increasing the therapeutic index. Target cell factors that influence response to low dose rate RIT have been elucidated and provide an opportunity to integrate the treatment modality into radical therapy regimens. A number of Phase I and II trials have now been performed in various tumour types. The results have been promising but, as yet, the prospect of radical RIT remains a research goal. Before it can be achieved it will be necessary to improve specific tumour cell targeting and to increase both the initial dose rates and the total dose delivered to tumour deposits. Until such time, it is likely that RIT will be incorporated into multimodality protocols to deliver a moderate (10-20 Gy) tumour boost, or in an adjuvant setting in patients with minimal residual disease.

Bronchogenic carcinoma: immunologic aspects

Evidence that host immunologic function may influence the behavior of lung cancer is accumulating. Non-small-cell lung cancers are heavily infiltrated by host lymphocytes. The fact that monoclonal antibodies have been developed against lung cancer cells implies that such cells express surface antigens and are therefore vulnerable to immune recognition. Failure of the host defense mechanism to control tumor growth may involve (1) reduced natural killer cell activity, (2) inadequate lymphokine-activated killer cell function, or (3) tumor secretion of immunomodulating factors. Basic immunologic research studies of lung cancer are increasing the potential for clinical applications. New monoclonal antibodies have improved both the sensitivity and the specificity of immunohistopathologic analyses of pulmonary specimens. Links between immune function and prognosis in patients with lung cancer have been established. Finally, initial results from protocols that have used tumor-infiltrating lymphocytes, interleukin 2, and tumor vaccines suggest that immunobiologic treatment modalities may be increasingly applicable in patients with lung cancer.

Monoclonal antibodies in cancer detection and therapy

Anticancer antibodies have had a long history in the management of cancer, with major applications having been shown in the immunohistochemistry and immunoassay of tumor-associated antigen markers. With the advent of hybridoma-derived monoclonal antibodies, attempts to use these more reproducible reagents in vivo for cancer detection and therapy have intensified. Radiolabeled monoclonal antibodies appear to be gaining a role in the management of cancer by means of imaging methods to detect sites of increased radioactivity, and several products have been developed and tested clinically. In the area of radioimmunotherapy, a number of problems still need to be solved, including low tumor uptake of the radioimmunoconjugate, dose-limiting myelotoxicity, and the induction of an immune response to repeated doses of murine (foreign) immunoglobulins. Similar problems exist for toxin and drug immunoconjugates, but these also fail to benefit from the "bystander" effect of the ionizing radiation delivered with radioimmunoconjugates, and plant and bacterial toxin molecules appear to have additional immunogenicity that restricts repeated injections. Despite these limitations, recombinant engineering and other chemical approaches are making progress in developing second-generation immunoconjugates that may be more efficacious and less immunogenic as cancer-selective therapeutics. Although nonconjugated, "naked", murine monoclonal antibodies have shown limited success in the therapy of human neoplasms, human and "humanized" forms may be more effective, particularly in lymphatic tumors. Some evidence also suggests that anti-idiotype antibodies (antiantibodies) may serve as surrogate antigens in cancer vaccines. Thus, a number of promising immunologic approaches for cancer diagnosis, detection, and therapy have made important progress in recent years.

Tumor-associated antigen 43-9F is of prognostic value in squamous cell carcinoma of the lung. A retrospective immunohistochemical study

BACKGROUND

Squamous cell lung carcinoma (SLC), the most frequent type of lung cancer, generally is treated surgically and its prognosis is poor. The only current clinically useful prognostic criterion is lymph node staging (TNM classification). Expression of a novel tumor-associated carbohydrate epitope Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-4[Fuc alpha 1-3]GlcNAc beta 1-3 Gal beta 1-4Glc identified by the 43-9F monoclonal antibody (MoAb) is associated with the growth pattern of SLC cell lines in athymic mice and in vitro. This implies that the 43-9F epitope may be related to tumor progression in patients with SLC and that, as such, it could be of prognostic value.

METHODS

Primary tumor specimens from 231 patients with lung carcinoma (130 with SLC, 64 with adenocarcinoma, 10 with small cell carcinoma, 16 with large cell carcinoma, and 11 with adenosquamous carcinoma) were examined by immunohistochemical studies on formalin-fixed, paraffin-embedded tissue samples for immunoreactivity with an MoAb to the 43-9F antigen. Univariate and step-wise Cox regression analyses were used to compare survival time by histopathologic diagnosis, smoker status, TNM classification, and type of surgical treatment.

RESULTS AND CONCLUSIONS

Patients with 43-9F epitope-positive SLC tumors had a significantly (P less than 0.01) better prognosis than patients with epitope-negative tumors. In contrast, no association was seen between 43-9F epitope expression and survival time for patients with lung adenocarcinomas. Further, the prognostic value of 43-9F expression in SLC was found to be superior to the N-classification with the added advantage that it requires access only to primary tumor tissue and thus is available before therapy.