A retrospective study of immunotherapy using the cell wall skeleton of Mycobacterium bovis Bacillus Calmette-Guérin (BCG-CWS) for cervical cancer

Abstract

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) has the potential to promote adaptive immunity. We sought to examine the synergistic effect of BCG-CWS vaccination on cervical cancer patients undergoing standard treatments including surgery, chemotherapy, and/or radiation. We retrospectively analyzed 103 patients (13 cases administered with BCG-CWS vaccine and 90 controls without BCG-CWS) who underwent a standard treatment for cervical cancer from 2005 to 2021. The BCG-CWS group underwent repeated intradermal injections of the BCG-CWS vaccine before or immediately after the standard therapy start from 2011 to 2018. The vaccination was repeated weekly for 1 month, and then every 4 weeks thereafter. The effectiveness of the BCG-CWS vaccination on cervical cancer treatment was evaluated by determining the hazard ratios of overall survival between the BCG-CWS group and the control group with multivariate analysis using the Cox model. Hazard ratios between 2 groups were determined after adjustment by clinical parameters including surgery, chemotherapy, radiation, age, clinical stage, presence of human papillomavirus, and pathology. Long-term follow-up revealed a significantly better prognosis (hazard ratio: 0.2108, P = .008 by the Cox model) for patients with cervical cancer in the BCG-CWS group compared to patients in the control group. Among patients with advanced cancer worse than stage IB2, some completely cleared the disease, whereas the others showed long-term survival with recurrence. BCG-CWS therapy appears to be an effective immune adjuvant therapy for cervical cancer, although randomized control studies are needed to confirm this. We also need to clarify the underlying mechanisms slowing the progression of cervical cancer in those receiving this vaccination. This study sheds light on the potential of immunostimulatory drugs such as BCG-CWS and suggests the important role of immunity for cancer elimination in combination therapy.