In a week marked by remarkable progress in blood cancer research, two major advances have captured the attention of the medical community and patients alike. At the heart of these breakthroughs are innovative therapies that promise hope for individuals facing aggressive or previously untreatable forms of leukemia and essential thrombocythemia (ET). Both stories, emerging from the United Kingdom and the United States, reflect years of scientific determination and the fierce resilience of patients and families who have participated in early trials.
For families confronting T-cell acute lymphoblastic leukemia (T-ALL), a rare and fast-growing blood cancer, the future has often felt daunting, especially when standard treatments fail. But now, as reported in the New England Journal of Medicine on December 8, 2025, researchers at University College London (UCL) and Great Ormond Street Hospital (GOSH) have developed a universal, base-edited CAR T-cell therapy known as BE-CAR7. This gene therapy is showing strong early results in both children and adults with resistant T-ALL, with 82% of patients in the clinical trial achieving very deep remission—enough to proceed to stem cell transplant with no detectable disease. Even more encouraging, 64% remain disease-free, with the earliest recipients now three years out from treatment and still off therapy.
The story of Alyssa Tapley, a now 16-year-old girl from Leicester, underscores just how transformative this advance can be. Diagnosed at age 13 in May 2021, Alyssa faced a grim outlook after chemotherapy and a first bone marrow transplant failed to halt her leukemia. According to SciTechDaily, she was even considering palliative care when she was offered the chance to become the first patient in the world to receive BE-CAR7. "I chose to take part in the research as I felt that, even if it didn’t work for me, it could help others. Years later, we know it worked and I’m doing really well. I’ve done all those things that you’re supposed to do when you’re a teenager," Alyssa shared, reflecting on her journey from hospital wards to sailing, completing her Duke of Edinburgh Award, and dreaming of a future as a research scientist.
The science behind BE-CAR7 is as compelling as the patient stories. This therapy uses base editing, a precise form of CRISPR gene editing that makes single-letter changes in DNA without cutting the double helix—thereby reducing the risk of chromosomal damage. The researchers engineered “universal” CAR T-cells from healthy donor white blood cells, removing certain markers (CD7 and CD52) to prevent friendly-fire and immune rejection, and then adding a chimeric antigen receptor that targets CD7 on leukemic T-cells. Once infused, these base-edited T-cells rapidly seek out and destroy cancerous T-cells. If the leukemia is cleared within about four weeks, patients proceed to a bone marrow transplant to rebuild their immune system.
Professor Waseem Qasim, who led the research, emphasized both the promise and the challenges: "We previously showed promising results using precision genome editing for children with aggressive blood cancer and this larger number of patients confirms the impact of this type of treatment. We’ve shown that universal or ‘off the shelf’ base-edited CAR T-cells can seek and destroy very resistant cases of CD7+ leukemia." Yet, he was quick to note, "These are intense and difficult treatments – patients and families have been generous in recognizing the importance of learning as much as possible from each experience." Side effects, such as low blood counts, cytokine release syndrome, and rashes, were manageable, though virus infections during immune recovery remain a concern.
Dr. Rob Chiesa, a bone marrow transplant consultant at GOSH, further highlighted the urgent need for better options: "Although most children with T-cell leukemia will respond well to standard treatments, around 20% may not. It’s these patients who desperately need better options and this research provides hope for a better prognosis for everyone diagnosed with this rare but aggressive form of blood cancer." Funding from the Medical Research Council, Wellcome, National Institute for Health and Care Research (NIHR), and GOSH Charity—over £2 million committed—will expand access, with the charity also supporting a new Children’s Cancer Centre at GOSH.
Meanwhile, across the Atlantic, another promising development is underway for patients with essential thrombocythemia (ET), a chronic myeloproliferative neoplasm characterized by persistently elevated platelet counts and a risk of blood clots, bleeding, and progression to myelofibrosis (MF) or acute leukemia. On December 7, 2025, Incyte announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to INCA033989, a first-in-class monoclonal antibody that targets mutant calreticulin (mutCALR) in ET patients with Type 1 CALR mutations who are resistant or intolerant to at least one cytoreductive therapy.
According to Business Wire, INCA033989 is designed to home in on malignant cells with mutCALR, sparing normal cells—a key distinction from traditional therapies. Early Phase 1 data, presented at the 2025 European Hematology Association Congress, showed that the antibody was well-tolerated and led to rapid, durable normalization of platelet counts, with stronger responses at higher doses. Updated safety and efficacy results, along with new data in myelofibrosis, are set to be unveiled at the American Society of Hematology (ASH) Annual Meeting in Orlando on December 8, 2025.
CALR mutations are found in roughly 25-35% of ET and MF patients, with the Type 1 mutation—present in 55% of those with CALR mutations—carrying the highest risk of progression to MF. "Incyte has long been committed to improving outcomes for patients with MPNs, and this Breakthrough Therapy designation underscores the potential of INCA033989 to be a novel therapy that could significantly transform the treatment of ET patients, who today have limited treatment options," said Pablo J. Cagnoni, M.D., President and Head of Research and Development at Incyte. The company plans to initiate a Phase 3 clinical program in mid-2026 to evaluate INCA033989 in ET patients with all types of CALR mutations, pending further regulatory discussions in early 2026.
Essential thrombocythemia, while less aggressive than T-ALL, carries its own risks and burdens for patients, who may face years of monitoring and treatment with limited options, especially if they become resistant to standard cytoreductive therapies. The hope is that targeted therapies like INCA033989 can change the landscape for these patients, offering not only better disease control but also improved quality of life.
Both advances—one in the UK, one in the US—underscore the power of targeted, precision medicine in the fight against blood cancers. They also highlight the importance of international collaboration, robust clinical trials, and the courage of patients and families who step forward for the sake of science and hope. As Alyssa Tapley’s journey reminds us, today’s breakthroughs are built on the resilience of yesterday’s pioneers, and tomorrow’s cures may well be within reach for those still waiting.
