Kitov Pharmaceuticals Holdings Ltd. announced results of a pre-clinical study demonstrating that NT-219, the lead drug candidate of its subsidiary TyrNovo Ltd., in combination with Keytruda®, converted non-responding tumors to responders and blocked tumor progression in an immune-oncology preclinical model. The study, conducted in collaboration with researchers at Bar Ilan University and Rabin Medical Center, assessed NT-219's ability to overcome cancer drug resistance in a patient-derived xenograft (PDX) model of immune-deficient mice, in which a tumor originated from an esophagus cancer biopsy was implanted. The mice were supplemented with immune cells from the same patient (double autologous). While no response was observed with Keytruda® alone or with NT-219 alone, and the tumors aggressively progressed, mice treated concomitantly with a combination of Keytruda® and NT-219 demonstrated complete blockage of tumor progression.