Treatment With Vonjo May Elicit Fewer Side Effects Than Other Available Therapies in Myelofibrosis, a Rare Type of Blood Cancer

JAK inhibitors are a mainstay in myelofibrosis treatment, but the side effects of these drugs may drastically impact patient quality of life.

However, recent research presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting found that Vonjo (pacritinib) had a comparable — if not superior — safety profile when compared with best available of therapy, including Jakafi (ruxolitinib). This was even seen in patients with low platelet counts.

Researchers analyzed data from two clinical trials (PERSIST-2 and PAC203), which included 160 patients who were prescribed Vonjo (106 on the PERSIST-2 trial and 54 from PAC203) and 98 patients who were prescribed best available therapy, including 44 who were given Jakafi.

At the start of treatment, more than half (61%) had received prior JAK inhibition therapy, and the average platelet count was 57x109/L.

“The safety analysis really tries to focus on these toxicities of interest for patients treated with pacritinib at 200 mg orally, twice daily and best available therapy, including ruxolitinib in the phase 2 and phase 3 studies,” study author Dr. Naveen Pemmaraju, an associate professor of Leukemia at The University of Texas MD Anderson Cancer Center in Houston, said while presenting the findings.

READ MORE: Small Percentage With Myelofibrosis Develop Aggressive Lymphoma from JAK Inhibition

There was an overall higher rate of side effects for patients on Vonjo, though the group had fewer side effects that resulted in death. Treatment with Vonjo was associated with fewer bleeding or cardiac (heart-related) events, with no major adverse cardiac events, whereas there were five in the best available therapy group. Thrombosis (blood clots in the veins or arteries) rates were similar between the two groups.

Infection was more prevalent in the Vonjo cohort, but fungal and viral infections happened less frequently for these patients compared to the best available therapy cohort. Additionally herpes zoster reactivation occurred less frequently in the Vonjo group than it did the best available therapy group.

There was a similar rate of secondary diseases between the two groups, with Vonjo having a statistically significant lower rate of non-melanoma skin cancer compared to patients prescribed the best available therapy.

“In this novel, risk-adjusted analysis, this project demonstrated that the safety profile of (Vonjo) … is comparable to (best available therapy),” Pemmaraju concluded. “(Vonjo) 200 mg may, indeed, represent a full-dose therapeutic option for patients with myelofibrosis, include for even those patients with (myelofibrosis) and thrombocytopenia.”

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