Daijiworld Media Network - London
London, Aug 18: Stem cell transplantation using donor cells could offer meaningful long-term survival to patients with hepatosplenic T-cell lymphoma, one of the rarest and most aggressive forms of blood cancer, according to findings from the largest study of its kind.
The disease has no established standard treatment and often responds poorly to chemotherapy. Researchers retrospectively analysed outcomes of 121 adults with confirmed or consistent-with diagnoses of hepatosplenic T-cell lymphoma treated at 64 centres across Europe and Asia.
Of the patients studied, 94 underwent allogeneic haematopoietic stem cell transplantation, using cells donated by another person, while 27 received autologous transplantation using their own previously collected stem cells.
Three years after an allogeneic transplant, 55% of patients remained alive, while 50.5% had remained free from relapse or disease progression.
Patients who entered transplantation in complete remission had nearly three times better odds of survival than those with active disease at the time of transplant.
However, the findings also showed that around one-third of patients whose disease was active and progressing before transplantation achieved long-term survival. Researchers said this suggests that patients with poor prognostic features should not automatically be excluded from consideration for a donor transplant.
The study also found that patients with normal levels of lactate dehydrogenase, or LDH, at diagnosis had significantly better outcomes than those with elevated levels. LDH is a commonly available blood test that can provide information about disease activity.
Relapse remained the biggest challenge, affecting around 38% of patients within three years. Meanwhile, deaths directly associated with the transplant procedure occurred in fewer than 12% of patients. Researchers noted that the relatively young age of the study population, whose median age was 36, may have contributed to the comparatively low treatment-related mortality.
The researchers said the results indicate a genuine, although incomplete, possibility of long-term disease control or cure through donor transplantation. They attributed much of the benefit to the graft-versus-lymphoma effect, in which immune cells from the donor attack remaining lymphoma cells.
Outcomes were considerably less favourable among patients who received autologous transplantation. Although this group was highly selected and 74% were in complete remission before transplantation, only about 39% remained free from disease progression three years later, while half experienced a relapse.
Researchers suggested that because autologous transplantation relies mainly on high-dose chemotherapy rather than a donor immune response, hepatosplenic T-cell lymphoma may be too resistant to chemotherapy for the benefits to persist.
With existing treatment recommendations based largely on limited evidence from small case series, the researchers said the new analysis, more than twice the size of previous studies, provides the most comprehensive outlook so far for patients with the disease.
They recommended aggressive initial chemotherapy followed by rapid allogeneic transplantation for eligible patients wherever possible. Autologous transplantation could be considered for patients who achieve complete remission but are not suitable candidates for a donor transplant.
The researchers acknowledged that the study included only patients who ultimately underwent transplantation and therefore could not provide information about patients who were considered for the procedure but did not receive it.
They said further research involving larger patient groups would be useful to confirm the findings, although the extreme rarity of hepatosplenic T-cell lymphoma is likely to continue limiting the size of future studies.