A possible abscopal effect of post-irradiation immunotherapy in two patients with metastatic lung tumors

Abstract

As well as its local effects, radiotherapy leads to the delayed regression of distant non-irradiated lesions. These abscopal effects are most likely mediated by the innate immune system. Patient 1, a 74-year-old male, had concomitant left supraclavicular lymph node metastases and multiple lung metastases 2 years after complete resection of pathological stage IIA (T1bN1M0) lung adenocarcinoma. He received radiation therapy (RT) of 58 Gy for the supraclavicular lymph node metastases and then innate immunotherapy using the cell wall skeleton of Mycobacterium bovis bacillus Calmette–Guerin (BCG-CWS). Three months after the RT and 2 months after the immunotherapy, all lung metastases disappeared on computed tomography scans. Patient 2, a 40-year-old female, underwent stereotactic body RT (SBRT) for metastasis from a deep-seated urothelial carcinoma in the right upper lobe of the lung. Twenty-one months after the SBRT, we started administration of BCG-CWS to two new lesions that had appeared in the left lung. As a result, after 3 months, the lesions completely disappeared. Complete response was maintained for more than 1 year in both patients. We believe that an optimal combination of RT and immunotherapy will elicit abscopal effects that can be employed to attain a systematically achievable, rather than anecdotal, therapeutic goal.