Recent clinical data announcements have further highlighted the potential of NK cell therapies of targeting cancers. Most pronounced from a stock perspective was Nkarta’s initial clinical data that now has positioned the company in a leading role within the field. Nkarta develops engineered natural killer cell (NK cell) therapies to combat cancer. NK cells are part of the innate immune system, our first line of defense against foreign cells and other pathogens. In addition, NK cells have the ability to find and clear out damaged and stressed cells, such as cancer cells.

NK cells have several advantages over the other group of cell therapies that are based on another immune cell, namely T-cells. Engineered T-cells or CAR-T cells are approved treatments for certain types of lymphomas and leukemias. T-cells are a part of the adaptive immune system and are triggered by specific binding to cells that the body want to get rid of. When CAR-T find tumor cells that they are designed to target they expand and proliferate aggressively. This is good for the cancer-killing properties of the treatment, but also causes severe side effect in some cases.  

Also, CAR-T cells are either manufactured from patient’s own cells – a sensitive and expensive process, or need to be exactly immunologically matched similarly to donor matching in stem cell transplantations.  If not matched, the injected CAR-T cells may cause a potentially very severe condition, graft versus host disease, whereby the foreign T-cell will attack any cell in the patient’s body. Meanwhile, NK cells can be freely donated between any persons. They do not expand like activated T-cell, meaning the safety profile of NK-cell therapy is more benign. Moreover, NK cells can be dosed multiple times and off-the-shelf administration is also easier, allowing for a streamlined manufacturing process. This comes in handy, since – unlike CAR-T cells – NK cells cannot persist and expand in the patient’s body, so they must be dosed multiple times to achieve a durable effect.

This concept is supported by Nkarta’s recently published dose escalation data in heavily pretreated cancer patients. NKX101, their lead cell therapy, showed 60% complete response rate in the highest dose group of acute myeloid leukemia patients, who have no further treatment options. Patients who received more doses and higher number of NK cells tended to show deeper responses in the trial, while the treatment was well tolerated for every patient group. Their other program, NKX019 also showed clear signs of dose response with the highest dose group achieving 83% overall response rate and 50% complete response rate in Non-Hodgkin’s Lymphoma (NHL). Additionally, responses across multiple types of NHL are also very encouraging together with the mild safety profile. Markets also appreciated these outstanding results as Nkarta’s stock price appreciated 140% on the day of the announcement.

In addition, other specialized NK-cell companies are coming through early-stage clinical development. Affimed recently published promising data with their NK-cell approach that involves a molecular approach to enhance the activation of NK-cells towards cancer cells. Fate Therapeutics, the largest NK-cell company measured in market cap, will have a data update soon, showcasing durability of responses. Finally, Dragonfly Therapeutics, that similarly to Affimed, works with activating an enhances NK-cell response, signed a USD 300 million upfront collaboration agreement with Gilead of a new therapeutic approach towards solid tumors.