Combination of JAK2 and PARP Inhibitors Shows Early Promise in Phase 1 Trial for Myelofibrosis
核心洞察
A phase 1 trial at Fox Chase Cancer Center and Temple University is combining the JAK2 (搜索) inhibitor pacritinib with the PARP (搜索) inhibitor talazoparib to treat myelofibrosis (搜索) patients who no longer respond to standard therapies.
Early results show significant symptom improvement, with severe patients' symptom scores dropping to single digits within three months, alongside clear biological evidence of increased cancer cell death.
The treatment was well tolerated, with patients remaining on therapy for nearly a year without serious side effects requiring discontinuation or dose reduction.
A collaborative phase 1 clinical trial led by Fox Chase Cancer Center and Temple University researchers is combining two FDA-approved medications to offer a new treatment option for patients with myelofibrosis (搜索), a rare blood cancer for which treatment options remain limited once standard therapies stop working.
The trial pairs pacritinib, a JAK2 (搜索) inhibitor commonly used to treat myeloproliferative neoplasms (搜索) (MPNs), with talazoparib, a PARP (搜索) inhibitor already approved for breast, ovarian, and prostate cancers. The approach emerged from research by Dr. Tomasz Skorski, director of the Fels Cancer Institute for Personalized Medicine at Temple University's Lewis Katz School of Medicine, in collaboration with Dr. Peter Abdelmessieh, assistant professor in the Department of Bone Marrow Transplant and Cellular Therapies at Fox Chase.
Exploiting a Molecular Vulnerability in MPN Cells
MPN cells accumulate extensive DNA damage that would normally kill them, but their cellular processes allow them to repair that damage. Dr. Skorski's research demonstrated that JAK2 (搜索) inhibitors do more than relieve symptoms—they also block key DNA repair systems, causing cancer cells to behave like cells lacking the tumor-suppressor genes BRCA1 or BRCA2, which are highly vulnerable to certain therapies.
"By understanding the vulnerabilities of MPN cells at the molecular level, we can strategically combine therapies to target the cancer while minimizing harm to healthy tissue," said Dr. Skorski. "Our goal is not just to manage symptoms, but to fundamentally change disease outcomes for patients."
This insight opened the door to a combination strategy: pairing a JAK2 (搜索) inhibitor with a PARP (搜索) inhibitor aims to overwhelm malignant cells with unrepaired DNA damage, resulting in targeted cancer cell death while largely sparing healthy tissue. Laboratory testing supported the theory and showed increased cell death of malignant cells carrying the JAK2 V617F mutation, forming the basis for the clinical trial.
Early Results Show Meaningful Benefits
Although the study remains in its early stages, the first patients treated have responded positively. Patients with severe disease saw their symptom scores drop from very high levels to single digits within three months. Many reported less fatigue, fewer night sweats, reduced bone pain, improved appetite, and a better overall quality of life.
Blood tests provided clear biological evidence that combining the two drugs increased cancer cell death, consistent with findings from earlier laboratory and animal studies. The treatment was also well tolerated, with patients remaining on treatment for nearly a year without serious side effects requiring the treatment to be stopped or the dose reduced.
Dr. Abdelmessieh described the primary objective of the therapy as decreasing symptoms by 50%, with treatment monitored by having patients rate their symptoms. He emphasized that the experimental therapy is not a cure but could offer a way to help manage the cancer.
Addressing an Unmet Need
Patients living with MPNs, a group of rare chronic blood cancers, have limited treatment options once standard therapies stop working. "Once available treatments stop working, patients often survive only about a year," said Dr. Abdelmessieh.
For Demetria Mears, a mother of four from Dover, Delaware, who has been fighting myelofibrosis (搜索) for more than a decade, the trial has been transformative. After standard chemotherapy failed, she enrolled in the Fox Chase trial. "Before coming to Fox Chase, I didn't really have a life. I couldn't go out, attend my daughter's basketball and soccer games, or enjoy time with friends. Now, my life has changed completely," she said. "I feel like a miracle, a miracle child because I feel 1,000% better."
From Discovery to Patient Care
Fox Chase is the first cancer center to explore this drug combination and the only site in Philadelphia conducting a study focused on myelofibrosis (搜索). Beyond improving symptoms, the trial is designed to deepen scientific understanding of how MPNs respond to treatment. Using advanced single-cell DNA sequencing, researchers will track which cancer cell populations are eliminated and which persist, helping anticipate resistance and guiding future combination strategies.
"We believe this approach is special and clearly addresses an unmet need," Dr. Abdelmessieh said. The next step is to enroll a total of 24 patients over the next few years.