Rigosertib Combination Phase 1/2a Trial To Continue Onconova announced the completion of three cohorts in its Phase 1/2a trial testing rigosertib in combination with the checkpoint inhibitor nivolumab (Opdivo). The data show signs of efficacy without reaching a maximum tolerated dose, justifying continuing the trial with higher dosing. We see this continuation and higher dosing as a positive signal of efficacy and safety.Interim Data Should Indicate Improved Responses The announcement indicates evidence of efficacy without side effects that would make treatment intolerable. Patient enrollment will continue at the current dose as trial protocols are amended to allow higher dosing. We believe this could indicate that rigosertib can improve response rates for checkpoint inhibitor therapies.Rigosertib Could Turn "Cold" Tumors "Hot" This investigator-initiated Phase 1/2a trial is testing the combination of rigosertib with the checkpoint inhibitor nivolumab in advanced metastatic non-small cell lung cancer (NSCLC) with KRAS mutations. This combination is intended to allow the checkpoint inhibitor to block the mechanism that allows cancer cells to avoid the immune system, while rigosertib stimulates the immune cells that carry out the killing steps.Trial Data Supported By Recent Publication On Mechanism of Action Preliminary data is scheduled for presentation at the 3rd Annual RAS Targeted Drug Development summit September 21-23, 2021. Earlier in June 2021, Onconova announced the publication of preclinical data demonstrating the cellular actions of rigosertib treatment. In addition to its effect on RAS cancer signaling pathways, rigosertib was shown to stimulate proliferation of immune cell types needed to kill cancer cells.Conclusion: The continuation of the Phase 1/2a trial with plans to increase dosing is good news for rigosertib development. We see this as a signal of efficacy, and look forward to the data presentation at the medical meeting in September. We reiterate our Outperform rating and price target of $11. Read More >>