Autologous and allogeneic stem cell transplantation in adult ALL: the Swedish Adult ALL Group experience

Approach to the Adult Acute Lymphoblastic Leukemia Patient

During recent decades, understanding of the molecular mechanisms of acute lymphoblastic leukemia (ALL) has improved considerably, resulting in better risk stratification of patients and increased survival rates. Age, white blood cell count (WBC), and specific genetic abnormalities are the most important factors that define risk groups for ALL. State-of-the-art diagnosis of ALL requires cytological and cytogenetical analyses, as well as flow cytometry and high-throughput sequencing assays. An important aspect in the diagnostic characterization of patients with ALL is the identification of the Philadelphia (Ph) chromosome, which warrants the addition of tyrosine kinase inhibitors (TKI) to the chemotherapy backbone. Data that support the benefit of hematopoietic stem cell transplantation (HSCT) in high risk patient subsets or in late relapse patients are still questioned and have yet to be determined conclusive. This article presents the newly published data in ALL workup and treatment, putting it into perspective for the attending physician in hematology and oncology.

Outcomes of Adults with Acute Lymphoblastic Leukemia After Autologous Hematopoietic Stem Cell Transplantation and the Significance of Pretransplantation Minimal Residual Disease: Analysis from a Single Center of China

Background:

The postremission therapies for adult patients generally contain consolidation chemotherapy, allogeneic hematopoietic stem cell transplantation and autologous hematopoietic stem cell transplantation (auto-HSCT). Because of the various results from different centers, the optimal therapy for adult acute lymphoblastic leukemia (ALL) patients is still uncertain. This study aimed to better understand predictive factors and role of auto-HSCT in the postremission therapy for adult ALL patients.

Methods:

The outcomes of 135 adult patients with ALL, who received the first auto-HSCT in Hematopoietic Stem Cell Transplantation Center of Blood Diseases Hospital, Chinese Academy of Medical Sciences from January 1, 1994 to February 28, 2014, were retrospectively analyzed. Survival curves were estimated using the Kaplan-Meier method and simultaneous effects of multiple covariates were estimated with the Cox model.

Results:

Overall survival (OS) and disease-free survival (DFS) at 5 years for the whole cohort were 59.1 ± 4.5% and 59.0 ± 4.4%, respectively. The cumulative nonrelapse mortality and relapse rate at 5 years were 4.5 ± 0.03% and 36.6 ± 0.19%. For both OS and DFS, acute T-cell lymphoblastic leukemia, high lactate dehydrogenase (LDH) at diagnosis, blast cell proportion ≥5% on the 15^th day of induction therapy, and extramedullary infiltration before HSCT were the poor prognosis factors. In addition, age ≥35 years predicted poor DFS. Only T-ALL and high LDH were the independent undesirable factors associated with OS and DFS in Cox regression model. For 44 patients who had results of pretransplantation minimal residual disease (MRD), positive MRD (MRD ≥0.01%) indicated poor OS (P = 0.044) and DFS (P = 0.008). Furthermore, for the standard risk group, the patients with negative MRD (MRD <0.01%) had better results (OS at 18 months was 90.0 ± 9.5%, while for the patients with positive MRD OS was 50.0 ± 35.4%, P = 0.003; DFS at 18 months was 90.0 ± 9.5%, while for the positive MRD group DFS was 0%, P < 0.001).

Conclusions:

This study confirmed that auto-HSCT combined with posttransplantation maintenance chemotherapy could be an option for adult ALL patients and pretransplantation MRD may play a significant role in the direction of therapy for adult ALL patients.

Outcome after HSCT in Philadelphia chromosome positive acute lymphoblastic leukemia in Sweden: a population-based study

Even in the tyrosine kinase inhibitor era, allogeneic hematopoietic stem cell transplantation (HSCT) is regarded as standard care for adult Philadelphia (Ph) positive acute lymphoblastic leukemia (ALL). In this retrospective national study, we have reviewed the outcome after HSCT in Sweden for adult Ph-positive ALL between 2000 and 2009. In total, 51 patients with median age 42 (range 20-66) years underwent HSCT. Mainly allogeneic HSCT was performed (24 related donor, 24 unrelated donor and one cord blood), and only two patients were treated with an autologous HSCT. The 5-year OS was 51 (37-64) %. The probabilities of morphological relapse and non-relapse mortality (NRM) at 5 years were 36 (23-49) and 18 (9-29) %, respectively. For the allogeneic transplanted, the 5-year OS was for patients <40 years 70 (50-90) % and for patients ≥40 years 34 (16-52) %, p = 0.002. The 5-year probability of NRM was for patients <40 years 10 (2-28) % compared to 25 (11-42) % for patients ≥40 years (p = 0.04). Patients with chronic graft-versus-host disease (GVHD) had a 5-year morphological relapse probability of 20 (6-40) % compared to 59 (35-77) % for patients without chronic GVHD (p = 0.03). Age ≥40 years and the absence of chronic GVHD were confirmed as independent negative prognostic factors for relapse and non-relapse mortality in a multivariate analysis although the impact of chronic GVHD was significant only in the older age cohort.

Unrelated transplantation for poor-prognosis adult acute lymphoblastic leukemia: long-term outcome analysis and study of the impact of hematopoietic graft source

Adults with high-risk acute lymphoblastic leukemia (HR-ALL) have a poor outcome with standard chemotherapy and usually undergo unrelated stem cell transplantation (SCT) if a matched sibling donor is not available. We analyzed the outcome of adult patients with unrelated SCT for HR-ALL and studied the possible effect of the hematopoietic stem cell source of the transplant. A total of 149 adult patients (median age, 29 years, range, 15-59 years) with HR-ALL underwent unrelated SCT in 13 Spanish institutions between 2000 and 2007. Patients in first complete remission (CR1) at transplantation had at least one adverse prognostic factor (advanced age, adverse cytogenetics, hyperleukocytosis, or slow response to induction therapy). ALL was in CR1 in 81 patients (54%), in second CR (CR2) in 37 patients (25%), in third CR (CR3) in 11 patients (7%), and with overt disease in 20 patients (13%). The hematopoietic source was unrelated cord blood (UCB) in 62 patients and an unrelated donor (UD) in 87 patients. The patients undergoing UCB-SCT and UD-SCT were comparable in terms of the main clinical and biological features of ALL, except for a higher frequency of patients with more overt disease in the UCB-SCT group. There was no statistically significant difference in overall survival (OS) or disease-free survival (DFS) at 5 years between the 2 groups. Treatment-related mortality (TRM) was significantly lower in the UCB-SCT group (P = .021). The probability of relapse at 1 year was 17% (95% confidence interval [CI], 7%-27%) for the UD-SCT group and 27% (95% CI, 14%-40%) for the UCB-SCT group (P = .088), respectively. Only disease status at transplantation (CR1, 41% [95% CI, 18%-64%] vs CR2, 51% [95% CI, 17%-85%] vs advanced disease, 66% [95% CI, 46%-86%]; P = .001) and the absence of chronic graft-versus-host disease (74% [95% CI, 46%-100%] vs 33% [95% CI, 17%-49%]; P = .034) were significant factors for relapse. All unrelated transplantation modalities were associated with high treatment-related mortality for adult HR-ALL patients without a sibling donor. UCB-SCT and UD-SCT were found to be equivalent options. Disease status at transplantation and chronic GVHD were the main factors influencing relapse in both transplantation modalities.

Management of Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL)

The tyrosine kinase inhibitor (TKI) imatinib has become an integral part of front-line therapy for Ph+ ALL, with remission rates exceeding 90% irrespective of whether imatinib is given alone or combined with chemotherapy. Treatment outcome with imatinib-based regimens has improved compared with historic controls, but most patients who do not undergo allogeneic stem cell transplantation (SCT) eventually relapse. Acquired resistance on TKI treatment is associated with mutations in the bcr-abl tyrosine kinase domain in the majority of patients, and may be detected at low frequency prior to TKI treatment in a subset of patients. Second generation TKIs, eg, dasatinib and nilotinib, show activity against most of the bcr-abl tyrosine kinase domain (TKD) mutations involved in acquired imatinib resistance, but clinical benefit is generally short-lived. Accordingly, SCT in first complete remission (CR) is considered to be the best curative option. Molecular monitoring of minimal residual disease levels appears to have prognostic relevance and should be used to guide treatment. International standardization and quality control efforts are ongoing to ensure comparability of results. Mutation analysis during treatment relies increasingly on highly sensitive PCR techniques or denaturing HPLC and may assist in treatment decisions, eg, in case of molecular relapse. Results from current studies of second-generation TKI as front-line treatment for Ph+ ALL are promising and show high molecular response rates, but follow-up is still too short to determine their impact on remission duration and long-term survival. Strategies to improve outcome after SCT include the pre-emptive use of imatinib, which appears to reduce the relapse rate. In patients ineligible for transplantation, novel concepts for maintenance therapy are needed. These could involve novel immunotherapeutic interventions and combinations of TKI.

Allogeneic Stem Cell Transplantation in First Complete Remission Enhances Graft-versus-Leukemia Effect in Adults with Acute Lymphoblastic Leukemia: Antileukemic Activity of Chronic Graft-versus-Host Disease

The aim of the present study was to identify graft-versus-leukemia effects and the factors that affect outcome in 201 adults with acute lymphobalstic leukemia who received myeloablative allogeneic stem cell transplantation from matched sibling or unrelated donors (1995-2004). One hundred seventy-eight (88.6%) of these patients had high-risk criteria, and 151 (75.1%) patients were transplanted in first complete remission (CR). All patients received unmodified stem cell grafts (185 bone marrow and 16 peripheral blood) following total- body irradiation-containing myeloablative preparations. Graft-versus-host disease (GVHD) prophylaxis was uniformly attempted by administering calcineurin inhibitor plus methotrexate. After a median follow-up of 63 months (range: 25+ to 139+ months) for surviving transplants, disease-free survival at 5 years was 47.8% for all patients and 60.3% for patients in the first CR. No difference in transplantation outcome was observed between sibling and unrelated transplants in the first CR. The most powerful predictive factor affecting transplantation outcome was disease status at transplantation (the first CR versus beyond the first CR, P<.001). Chronic GVHD (cGVHD), especially limited type, was also found to have a significant antileukemic effect. Interestingly, the influence of cGVHD on relapse risk was prominent in patients with chromosomal translocations or normal cytogenetics.

Event-free survival and cost-effectiveness in adult acute lymphoblastic leukaemia in first remission treated with allogeneic transplantation

Allogeneic transplantation in patients with acute lymphoblastic leukaemia in first remission (ALL-CR1) has been studied in several clinical trials. However, no pooled survival analysis has yet been done. We conducted a survival meta-analysis to compare allogeneic transplantation vs chemotherapy or autologous transplantation using an intention-to-treat approach. Our study included the controlled clinical trials, wherein allocation to allogeneic transplant was based on donor availability. The event-free individual survival data were reconstructed on the basis of published information and Kaplan-Meier graphs. We then generated the meta-analytic event-free survival curves for the two treatments. The mean survival gain per patient was estimated and a simplified cost-effectiveness assessment was carried out. In the allogeneic transplantation group, 293 patients were examined and 479 as controls (four trials). The event-free survival difference was statistically significant (P=0.011). The relative risk for event occurrence was 0.79 for the experimental group vs the controls (95% CI: 0.66-0.96; P=0.017). The mean survival gain was 1 year per patient. The cost per life-year gained was less than the conventional threshold of 50,000 euros. Allogeneic transplantation in ALL-CR1 improves event-free survival as compared to chemotherapy or autologous transplantation. Its cost-effectiveness profile is acceptable.

Relapse of preB-ALL after rituximab treatment for chronic graft versus host disease. Implications for its use?

In acute lymphatic leukaemia (ALL) treated with allogenic stem cell transplantation limited chronic graft versus host disease (cGVHD) is associated with a higher 5 year disease free survival. This indicates an important graft-versus-leukemia (GVL) effect, although this effect is less pronounced in ALL than in other malignancies. B-cell depletion using Rituximab is a treatment option in therapy refractory cGVHD that has been used successfully in a limited number of patients with an approximate response rate of 70%. Only two ALL patients with cGVHD treated with Rituximab are found in the literature. Here we describe a pre-B-ALL patient with therapy refractory cGVHD who relapsed only one month after receiving Rituximab therapy for cGVHD. The Rituximab therapy may have triggered the relapse by targeting the shared cGVHD and GVL mechanisms, diminishing the GVL effect. Although no definite conclusions can be drawn from one case this might have implications for the use of Rituximab in cGVHD in ALL patients.

Philadelphia chromosome-positive acute lymphoblastic leukemia: impact of imatinib treatment on remission induction and allogeneic stem cell transplantation

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with the worst patient survival rates of the various acute leukemias. Imatinib mesylate is a novel therapeutic agent that targets the BCR-ABL tyrosine kinase, the molecular abnormality associated with Ph+ ALL. The combination of imatinib with chemotherapy has led to improved and durable treatment responses in adult patients with Ph+ ALL, including the elderly population. Hematopoietic stem cell transplantation has also integrated imatinib into its transplant strategies, with early data suggesting improved progression-free survival without clearly identifiable augmented toxicity. Second-generation tyrosine kinase inhibitors offer potentially even greater improvements on these excellent imatinib-associated outcomes. This review addresses the evolution of the management of Ph+ ALL and is intended to assist in the description of its new natural history.

Autologous stem cell transplant in ALL: who should we be transplanting in first remission?

Long-term disease-free survival (DFS) has been reported after autologous stem cell transplantation for acute lymphoblastic leukemia. Phase II studies have evaluated its role in first and subsequent complete remission (CR) with DFS rates of up to 50%. It has been under-utilized in 1st CR in part, due to a concern that patients who relapse after autologous stem cell transplantation (ASCT) have fewer options for salvage treatment of relapsed disease. Unfortunately, survival rates of <5% are reported in patients who relapse, regardless of initial therapy. Few prospective, randomized trials have analyzed large enough numbers of patients to allow us to determine the appropriate patient population for autologous transplantation. Although variability in the available studies makes it difficult to draw a definite conclusion, and many issues remain unresolved, available data suggests that there may be a group of patients for whom ASCT in first remission is a reasonable and perhaps superior treatment choice. Factors such as risk features at diagnosis, and minimal residual disease following induction therapy greatly affect outcome following ASCT. The available data as well as the questions that remain to be answered will be discussed and reviewed.