Durable tumour responses following primary high dose induction with mistletoe extracts: Two case reports

IntroductionViscum album L. extracts (VAEs) are widely used in the complementary treatment of cancer, to improve quality of life of cancer patients, commonly using subcutaneous application of low doses of VAEs.Case presentationsTwo patients were treated with VAE (AbnobaViscum®) alone, using a combination of intratumoural, subcutaneous and in one case intravenous administration. A 75-year-old lady with relapsed Merkel cell cancer - a rare and aggressive neuro-endocrine cancer of the skin - declined radiotherapy, and was treated with VAE alone over 9.8 months, using a total of 5.8G VAE, averaging 592 mg/VAE/month (>300,000 ng mistletoe lectin (ML)/month; >2300 μg viscotoxin (VTX)/month); the 3 cm tumour was impalpable after 4 months and she continues to be in complete remission after 3 years. A 50-year-old postmenopausal woman with asynchronous bilateral breast cancer (right breast: grade 1, hormone sensitive; left breast: grade 3, hormone insensitive and HER2-positive ductal carcinoma), declined all conventional cancer treatment. She was treated with VAE alone for 2.6 years, with a total of 8.9G VAE, averaging 290 mg/month (>150,000 ng ML/month; >1200 μg VTX/month); she had complete responses of both tumours after 31 months of intratumoural and subcutaneous VAE application, and remains in remission after 4 years.ConclusionsDurable tumour regression occurred in 2 patients following treatment with VAE, used in higher than generally used doses and combining different applications. Both patients had no other established cancer therapies. Further studies are required to define the strategic role of VAE and its different applications, safety and efficacy.