Here’s an interested case of a patient with MCC that I saw this past week. While I’d like to consider systemic immunotherapy with PD1 or dual checkpoint inhibitors, chemotherapy, clinical trial with MDNA or TLR9 agonist/PD1, this patient’s disease was limited to the skin alone. Could we do something different and perhaps with less risk of systemic adverse effects.
In the ever-evolving landscape of cancer treatment, the tools in an oncologist’s arsenal are constantly being refined and expanded. One particularly intriguing development is the use of TVEC (Talimogene laherparepvec) in treating certain types of cancers, including Merkel cell carcinoma.
Merkel cell carcinoma (MCC), while relatively rare, can pose unique challenges when it comes to treatment, particularly in its later stages. I had a poignant reminder of this when treating an elderly male patient diagnosed with stage III Merkel cell carcinoma. He had undergone a complete resection, received adjuvant radiotherapy, and even benefitted from six months of off-label adjuvant immunotherapy. However, a year later, he presented with a few new skin lesions, each measuring between 2-4 mm and two of these lesions were biopsied proven recurrent MCC.
The challenge? The limited nature of his disease made him ineligible for many of the clinical trials currently available. Options like chemotherapy or another round of immunotherapy remained on the table, but his skin-limited condition pointed me towards an alternative: intra tumoral treatment using TVEC. Talimogene Larherperepavec
TVEC is not your typical treatment. It is a modified live herpes virus designed to directly target cancer cells, leaving surrounding healthy cells unharmed. But how does it achieve this? By cleverly taking over the molecular machinery of the cancer cell, TVEC replicates itself. More intriguingly, it produces a protein called GM-CSF, thanks to a specific gene that was intentionally inserted into the TVEC’s genome. This protein triggers a potent local inflammatory response, acting like a magnet for immune cells integral to our body’s inflammatory and immune responses.
The beauty of TVEC doesn’t end there. The debris from dead cancer cells, rich in cancer-specific antigens, is captured by the patient’s immune system. This helps the immune system recognize similar antigens on live cancer cells elsewhere, making TVEC not just a viral therapy but an effective form of immunotherapy.
The potential of TVEC isn’t just theoretical. A noteworthy case report by Dr. Calento and Klein illustrates the power of TVEC in a MCC. Their patient, previously treated with radiation, chemotherapy, and immunotherapy, showed a significant response to TVEC treatment. Such cases underline the potential of TVEC in effectively managing skin-limited cancers.
While my preference leans towards clinical trials when viable, given the unique circumstances of this case, coupled with the recent endorsement of TVEC by the NCCN guidelines, I believe TVEC might be the weapon we need to address these tiny but tenacious tumors. Time will tell, but hope is a powerful medicine.
About the author
As one of the principal investigators at his cancer center, Dr. Thomas plays a pivotal role in advancing medical knowledge through his involvement in numerous clinical trials. These trials encompass a spectrum of cutting-edge treatments, including targeted therapy, immunotherapy, intra tumoral therapy, and complex cellular therapies. His commitment to research and innovation underscores his dedication to offering the most effective and up-to-date treatment options to his patients.Embrace the opportunity to engage with Dr. Sajeve’s expertise, and feel empowered to explore the vast expanse of oncology with renewed curiosity and understanding on “Ask MedOnCMD“