Metastatic squamous non-small cell lung cancer – complete response following desmocollin-3 targeting immunotherapy as a monotherapy – A case report

Non-small cell lung cancer (NSCLC) constitutes the majority of lung cancer cases. Among them, about one-third of the cases are of the squamous cell subtype and are associated with a poor prognosis compared to non-squamous NSCLC. Immunotherapy in the form of checkpoint inhibitors targeting the cell surface receptor PD-1, i.e. pembrolizumab plays a pivotal role in the treatment of advanced squamous NSCLC in the absence of the driver mutation and has become one of the first-line therapies. However, in patients with negative expression of PD-L1 and poor performance status, no optimal therapeutic strategy has been defined. A heat-killed Mycobacterium w (Mw) is a potent Toll-like receptor-2 (TLR-2) agonist, which induces a cell-mediated immune response targeting cancer cells expressing Desmocollin-3 (DSC3). Mw has been approved in India for the treatment of advanced NSCLC along with chemotherapy. Mw has shown maximum benefit in patients with squamous NSCLC without any added systemic toxicity. We present the case of a 65-year-old patient with PD-L1 negative and desmocollin-3 (DSC3) positive metastatic Squamous NSCLC achieving a durable and complete response after monotherapy with heat-killed Mycobacterium w (Mw).