Abstract
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Objectives: 177Lutetium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid (177Lu-DOTMP) is a new bone seeking therapeutic radiotracer. Objectives of this study were to evaluate the efficacy of 177Lu-DOTMP (a) in reducing bone pain, (b) in improving the quality of life (QOL) and (c) to study the toxicity profile in patients with biopsy proven carcinoma with skeletal metastasis.
Methods: Ongoing prospective interventional study being conducted since July 2017. Patients (≥18 years) with painful skeletal metastases from prostate, breast, lung and nasopharyngeal carcinoma documented on 99mTc-MDP bone scan were administered with single dose (37 MBq /kg) of 177Lu-DOTMP intravenously. Post therapy whole body images were acquired after 24 hours to confirm distribution of 177Lu-DOTMP at the skeletal metastatic sites. Response was assessed by analysing visual analogue score (VAS), analgesic score (AS) and Eastern Cooperative Oncology Group (ECOG) score at baseline and 1, 2, 4, 8, 12 weeks post therapy. Response was graded as- significant: >50% reduction in post therapy VAS compared to baseline; partial response: 10-50% reduction in VAS and no response : 0-10% VAS reduction. Toxicity was assessed and graded according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE version 5).
Results: Eighteen patients (13 males, 5 females) with mean age 56 years were recruited in the study. Overall response was seen in 14 patients (78%) which was significant in 10 patients. Partial response was seen in 4 patients whereas 4 had not response to therapy. In responders, pain relief started at a median duration of 7 days (range 4-20 days) post therapy, with the maximum pain relief at 8 weeks. Statistically significant reduction in mean VAS was noted, from 7.9 at baseline to 3.9 at 4 weeks and 2.5 at 8 weeks post therapy (p<0.001). Mean AS reduced to 2.5 and 1.6 at 4 and 8 weeks post therapy from 3.8 at baseline (p<0.001). Improvement in QOL was noted in nine (50%) patients as evidenced by improvement in the mean ECOG score from 3.0 at baseline to 2.6 at 1month post therapy (p=0.02). Among the subset of the patients treated, best response rate was seen in breast carcinoma patients (100%) and least response rate in lung carcinoma patients (40%). Grade II/III anemia and thrombocytopenia were the only notable adverse events noted after therapy with spontaneous recovery within next 4 weeks in all patients except two in whom blood transfusion was given. Anemia was noted in nine patients with median nadir at 4 weeks (range 2-12 weeks) whereas thrombocytopenia was noted in four patients with median nadir at 3 weeks (range 1-4 weeks).
Conclusions: 177Lu-DOTMP is proven to be safe and effective therapeutic radiotracer in reducing metastatic bone pain along with significant improvement in quality of life of breast, prostate and nasopharyngeal carcinoma patients.