Analysis of absorbed dose in radioimmunotherapy with 177Lu-trastuzumab using two different imaging scenarios: a pilot study

Internal dosimetry and biodistribution of indigenously prepared 177 Lu-DOTA-rituximab in lymphoma and other hematological malignancies treated with rituximab

OBJECTIVE

The aim of this study was to evaluate the biodistribution and dosimetry of lutetium-177-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid ( 177 Lu-DOTA)-rituximab in CD20 + non-Hodgkin's lymphoma and other hematological malignancies treated with rituximab.

METHODS

The standard dosimetry protocol was used, with cold rituximab infusion, then a diagnostic activity of 177 Lu-DOTA-rituximab. Planar images were acquired at multiple time points. Normal organs and tumor dosimetry were performed by using organ and tumor-specific regions of interest and whole-body counts were obtained serially after pixel matched, background, scatter, and attenuation correction. The mean radiation absorbed doses were obtained from OLINDA/EXM v2.1.1 and ORIGIN software.

RESULTS

A total of 22 patients were included in this study. Prolonged blood pool clearance of 177 Lu-DOTA-rituximab with long residence time in the blood pool and normal organs were observed. The whole body effective half-life was 104.5 ± 22 h. The mean total body radiation absorbed dose was 0.208 ± 0.03 mGy/MBq and the mean total body effective dose was 0.196 ± 0.05 mGy/MBq of 177 Lu-DOTA-rituximab. The mean radiation absorbed doses of 0.613 ± 0.21, 1.68 ± 2, 1.01 ± 0.42, and 0.136 ± 0.02mGy/MBq were seen for the liver, spleen, kidneys, and bone marrow, respectively. Tumor lesion uptake was noticed in two patients with tumor radiation absorbed doses were 0.842 mGy/MBq in one and 9.9 mGy/MBq in the other patient. A strong correlation was obtained between the cumulative activities of radiation-absorbed doses derived from ORIGIN and OLINDA software methods at a significant P value less than 0.001.

CONCLUSION

The results of our study demonstrated favorable biodistribution and dosimetry of indigenously produced 177 Lu-DOTA-rituximab in patients with CD20 + lymphoma. These results can be used for future studies of radioimmunotherapy employing 177 Lu-DOTA-rituximab.

Clinical Internal Dosimetry and Biodistribution of 177 Lu-DOTA-Trastuzumab in HER2-Positive Metastatic and Locally Advanced Breast Carcinoma

OBJECTIVE

The aim of this study was to assess the biodistribution and dosimetry of 177 Lu-DOTA-trastuzumab in patients with HER2-positive breast carcinoma using whole-body (WB) planar imaging at multiple time points.

PATIENTS AND METHODS

This study was a prospective evaluation of HER2-positive metastatic/locally advanced breast carcinoma patients who underwent gamma camera imaging for dosimetry and biodistribution studies by using 177 Lu-DOTA-trastuzumab. The standard diagnostic dosimetry protocol was followed, which included cold trastuzumab injection followed by in-house produced 177 Lu-DOTA-trastuzumab. Serial WB planar images (anterior and posterior) were obtained on gamma camera after the infusion of 177 Lu-DOTA-trastuzumab at multiple time points. Whole-body and organ regions of interest were drawn, and the numbers of disintegrations were obtained. The mean absorbed doses for the liver, spleen, kidneys, heart, red marrow, and tumor were obtained from OLINDA EXM v2.1.1 and ORIGIN software.

RESULTS

The study included a cohort of 21 female breast carcinoma patients. Tracer activity ( 177 Lu-DOTA-trastuzumab) was noted in the physiological organs such as the liver, spleen, kidneys, heart, as well as in the tumors. On visual analysis of 177 Lu-DOTA-trastuzumab biodistribution, the liver activity showed gradual clearance over time, and although spleen was comparatively faintly visualized than liver and similarly, kidneys were faintly visualized suggestive of the alternate route of tracer excretion. The maximum number of patients (n = 12) showed 2 components of clearance, namely, fast and slow. The average effective half-life of all the patients (including single and 2 components of clearance) was 106.25 ± 22.14 hours (84.11-128.39 hours). The mean absorbed dose for the liver, spleen, kidneys, heart, whole body, and red marrow was 1.0702 ± 0.731, 1.4114 ± 0.462, 1.4232 ± 0.364, 1.4719 ± 0.602, 0.2412 ± 0.0295, and 0.1485 ± 0.0213 mGy/MBq, respectively, by OLINDA EXM and 0.5741 ± 0.333, 0.8096 ± 0.224, 0.7943 ± 0.235, 1.8971 ± 0.713, and 0.09619 ± 0.0144 for liver, spleen, kidneys, heart and whole body respectively by ORIGIN. The absorbed radiation dose for tumor was 1.94E+2 by OLINDA EXM software and 1.78E+2 by ORIGIN software. In this study, during and after infusion of 177 Lu-DOTA-trastuzumab, no major adverse effects were noted in any patient except 1 patient who had grade 1 nausea and managed conservatively by antiemetic drug.

CONCLUSIONS

The results of our study demonstrated expected and favorable biodistribution and dosimetry with 177 Lu-DOTA-trastuzumab in HER2-positive breast carcinoma patients. We noticed the mean absorbed dose to the normal organs within the limits of maximum tolerable dose, and also tumor dose was higher than the normal liver dose. Therefore, we conclude that 177 Lu-DOTA-trastuzumab radioimmunotherapy is feasible and a safe treatment option for treating HER2-positive breast carcinoma patients.

The current role of nuclear medicine in breast cancer

Breast cancer is the most common cancer in females worldwide. Nuclear medicine plays an important role in patient management, not only in initial staging, but also during follow-up. Radiopharmaceuticals to study breast cancer have been used for over 50 years, and several of these are still used in clinical practice, according to the most recent guideline recommendations.In this critical review, an overview of nuclear medicine procedures used during the last decades is presented. Current clinical indications of each of the conventional nuclear medicine and PET/CT examinations are the focus of this review, and are objectively provided. Radionuclide therapies are also referred, mainly summarising the methods to palliate metastatic bone pain. Finally, recent developments and future perspectives in the field of nuclear medicine are discussed. In this context, the promising potential of new radiopharmaceuticals not only for diagnosis, but also for therapy, and the use of quantitative imaging features as potential biomarkers, are addressed.Despite the long way nuclear medicine has gone through, it looks like it will continue to benefit clinical practice, paving the way to improve healthcare provided to patients with breast cancer.

PET/CT and SPECT/CT Imaging of HER2-Positive Breast Cancer

HER2 (Human Epidermal Growth Factor Receptor 2)-positive breast cancer is characterized by amplification of the HER2 gene and is associated with more aggressive tumor growth, increased risk of metastasis, and poorer prognosis when compared to other subtypes of breast cancer. HER2 expression is therefore a critical tumor feature that can be used to diagnose and treat breast cancer. Moving forward, advances in HER2 in vivo imaging, involving the use of techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT), may allow for a greater role for HER2 status in guiding the management of breast cancer patients. This will apply both to patients who are HER2-positive and those who have limited-to-minimal immunohistochemical HER2 expression (HER2-low), with imaging ultimately helping clinicians determine the size and location of tumors. Additionally, PET and SPECT could help evaluate effectiveness of HER2-targeted therapies, such as trastuzumab or pertuzumab for HER2-positive cancers, and specially modified antibody drug conjugates (ADC), such as trastuzumab-deruxtecan, for HER2-low variants. This review will explore the current and future role of HER2 imaging in personalizing the care of patients diagnosed with breast cancer.