FDA Approves Syndax's Revuforj for Aggressive Leukemia

Syndax Pharmaceuticals secured its first FDA approval last week for a novel category of medications known as menin inhibitors. The approved drug, Revuforj, is set to be available this month to treat patients with a particularly aggressive type of leukemia linked to the rearrangement of the KMT2A gene. This genetic alteration is responsible for around 10% of acute leukemias, as reported by Syndax. CEO Michael Metzger emphasized that this mutation is particularly severe as it primarily affects children and younger adults.

Revuforj is priced at $39,500 for a 30-day supply. The FDA's approval was grounded in data from an open-label study involving 104 adult and pediatric patients. The study revealed that 21% of patients with the KMT2A gene rearrangement achieved complete remission, including some patients who experienced complete remission with only partial hematological recovery, technically referred to as CR/CRh. The median duration of complete remission observed was 6.4 months.

The drug carries a boxed warning for differentiation syndrome, a potentially fatal reaction seen in some blood cancer treatments. During clinical trials, differentiation syndrome occurred in 29% of patients treated with Revuforj, resulting in one death. Syndax executives noted that other targeted therapies approved for acute myeloid leukemia also include boxed warnings for similar risks. Additionally, Revuforj has a standard warning for irregular heart rhythms, a condition that CEO Metzger previously stated is usually detectable and manageable by adjusting the dose.

Following the approval, Syndax's stock ($SNDX) increased by 2% on Monday afternoon. The approval came as positive news after a less-than-enthusiastic response from investors to Syndax’s recent data presentation for another type of acute leukemia.

Last Tuesday, Syndax announced that Revuforj met the primary endpoint in a crucial trial for leukemia patients with a mutation in the NPM1 gene, which is a more prevalent alteration than KMT2A. According to Syndax, NPM1 mutations are found in about 30% of adult acute myeloid leukemias. The company intends to seek FDA approval for treating this condition in the first half of 2025.

However, analysts noted that the NPM1 results did not meet expectations and investors are keenly awaiting data from Kura Oncology, which plans to reveal pivotal results for its competing menin inhibitor in NPM1-mutated AML patients next year. B Riley Securities analysts remarked that while Syndax is anticipated to "achieve dominance" in the KMT2A market, competition in the NPM1 segment is expected to be more intense, with similar efficacy predicted between revumenib and Kura Oncology’s ziftomenib.