Anemia Advantage For GSK's Blood Cancer Therapy Could Influence Market Share Despite Incyte's Jakafi Comparison

Friday, the FDA approved GSK plc's GSK Ojjaara (momelotinib) for intermediate or high-risk myelofibrosis, including primary myelofibrosis or secondary myelofibrosis (post-polycythemia vera and post-essential thrombocythaemia), in adults with anemia. 

William Blair notes four JAK inhibitors approved for myelofibrosis - Incyte Corporation's INCY (Outperform rating reiterated) Jakafi, Bristol-Myers Squibb Co's BMY Inrebic, CTI BioPharma Corp's Vonjo, and Ojjaara.

None of the labeled indications require prior JAK inhibitor therapy, even though clinical results supporting Inrebic, Vonjo, and Ojjaara's approval were largely studied in second-line or Jakafi-ineligible patient populations. 

Considering that Ojjaara failed to beat Jakafi in the head-to-head SIMPLIFY-1 trial, William Blair analyst says there is no reason why Ojjaara will be the new standard of care broadly in the indication. 

Also, recall that Ojjaara failed to beat the best available therapy (89% of patients received Jakafi) in the SIMPLIFY-2 study. However, with roughly a third of myelofibrosis patients having anemia, the lower transfusion burden observed with Ojjaara in clinical studies provides another option for physicians, pressuring Jakafi dominance in the indication.

William Blair notes that its estimates for Jakafi in myelofibrosis assume a gradual decrease in the market share of newly diagnosed patients between now and 2028, resulting in lowering Jakafi's peak sales by $125 million to $150 million.

Price Action: INCY shares are down 4.11% at $59.98 on the last check Monday.