Clinical experience with intra lymphatic administration of 111In-labelled monoclonal antibody PAY 276 for the detection of pelvic nodal metastases in prostatic carcinoma

Noninvasive detection of cancer spread to lymph nodes: A review of molecular imaging principles and protocols

Identification of cancer spread to tumor-draining lymph nodes offers critical information for guiding treatment in many cancer types. Current clinical methods of nodal staging are invasive and can have substantial negative side effects. Molecular imaging protocols have long been proposed as a less invasive means of nodal staging, having the potential to enable highly sensitive and specific evaluations. This review article summarizes the current status and future perspectives for molecular targeted nodal staging.

Assessment of free dye in solutions of dual-labeled antibody conjugates for in vivo molecular imaging

PURPOSE

Recent preclinical and clinical studies show that dyes that excite and fluoresce in the near-infrared range may be used for tracking and detecting disease targets in vivo. A method for quantifying free dye molecules in antibody conjugate preparations is required for agent batch release and for translation into the clinic.

PROCEDURES

Herein, we developed and validated a SDS-PAGE method to determine the percentage of free IRDye 800 CW in (DTPA)(n)-trastuzumab-(IRDye 800)(m) conjugate sample preparations in which high-performance liquid chromatography (HPLC) assessment of free dye was not possible.

RESULTS

The SDS-PAGE assay was accurate and valid for free IRDye 800 CW amounts between 38 and 4 mol% of total dye. Gel sample preparation reagent affected the specificity of the assay, and lower and upper limits of quantitation and detection were determined.

CONCLUSION

This method may be applicable to other near-infrared dye-conjugated antibody-based imaging agents in which HPLC assessment of purity is not feasible. This validated method for quality assurance will facilitate the translation of dual-labeled antibody conjugates for nuclear and optical imaging.

Near infrared fluorescent optical imaging for nodal staging

Current techniques to assess lymph node metastases in cancer patients include lymphoscintigraphy after administration of a nonspecific radiocolloid in order to locate and resect lymph nodes for pathological examination of harbored cancer cells. Clinical trials involving intradermal or subcutaneous injection of antibody-based nuclear imaging agents have demonstrated the feasibility for target-specific, molecular imaging of cancer-positive lymph nodes. The basis for employing near-infrared (NIR) optical imaging for assessing disease is evidenced by recent work showing functional lymph imaging in mice, swine, and humans. We review antibody-based immunolymphoscintigraphy with an emphasis on the use of trastuzumab (or Herceptin) to target human epidermal growth factor receptor-2 (HER2) overexpressed in some breast cancers. Specifically, we review in vitro and preclinical imaging data from our laboratory that show how the dual-labeled agent ((111)In-DTPA)(n)-trastuzumab-(IRDye800)(m) utilizes the high photon count provided by an NIR fluorescent dye, IRDye 800CW, and the radioactive signal from a gamma emitter, Indium-111, for possible detection of HER2 metastasis in lymph nodes. We show that the accumulation and clearance of ((111)In-DTPA)(n)-trastuzumab-(IRDye800)(m) from the axillary nodes of mice occurs 48 h after intradermal injection into the dorsal aspect of the foot. The requirement for long clearance times from normal, cancer-negative nodes presents challenges for nuclear imaging agents with limited half-lives but does not hamper NIR optical imaging.

Antibody imaging in breast cancer

Radiolabeled antibodies have been studied by several investigators for their ability to detect and stage breast cancers. Studies with Technetium-99m labeled anti-CEA monoclonal antibodies, Iodine-123, Indium111 labeled anti-mucin antibodies such as HFMG, B72.3, anti-TF and Iodine-125 labeled B72-3 have demonstrated the ability of radioimmunoscintigraphy in detecting over 80% of breast cancer lesions, but lower sensitivity and specificity for accurate staging of the axillae. Non-specific localization of radiolabeled monoclonal antibodies in tumor negative nodes even following lymphoscintigraphy appear to be the major factor limiting the widespread clinical application of radioimmunoscintigraphy in staging newly diagnosed breast cancer patients. Preliminary studies with Tc-99m labeled CEA-Scan appear to indicate a useful role of this agent in distinguishing between benign and malignant breast lesions in patients with indeterminate mammographic findings.

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.

Radioimmunodetection of prostate cancer by 111In-labeled monoclonal antibody against prostatic acid phosphatase

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragments were labeled with indium-111 chloride. This labeled antibody was tested in 15 prostate cancer patients who underwent staging pelvic lymphadenectomy; 9 of them received labeled antibody alone whereas 6 received simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blood measurements and imaging procedures indicated that simultaneous injection of unlabeled antibody reduced both the blood elimination rate and the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a couple of patients accumulation was noted also in normal lymph nodes. The method cannot in its present design replace staging pelvic lymphadenectomy and further studies are needed for elaboration of clinically useful radioimmunodetection methods.