Treatment of adults with acute lymphoblastic leukaemia in first bone marrow relapse: results of the ALL R-87 protocol

How should we treat a patient with relapsed Ph-negative B-ALL and what novel approaches are being investigated?

Despite significant improvements in outcome of newly diagnosed B-precursor ALL, the results in relapsed or refractory adult ALL are overall poor. Large retrospective studies revealed significant differences in terms of outcome, with particularly poor response rates in early or refractory relapses, whereas late relapses usually respond very well to repeated standard induction. Particularly new immunotherapy compounds like the CD19 bispecific antibody Blinatumomab and the conjugated CD22 antibody Inotuzumab yielded promising response rates compared to standard therapies in randomised trials. Long-term survival is however still poor. The optimal use of these compounds remains to be defined. Chimeric antigen receptor T-cells are another promising treatment approach and multicenter clinical trials in adult ALL are awaited. For selected patients molecular directed therapies may have a role in relapsed ALL; standard diagnostic algorithms need to be defined. One of the major challenges is to define the role of stem cell transplantation after relapse. Whereas this procedure appears to be the only chance for cure, the mortality and relapse rate are still high and optimisation is urgently needed. Future strategies include optimised use of new compounds as part of combination regimens and the earlier treatment of upcoming relapse in the situation of persistent or recurrent minimal residual disease.

Salvage therapy with mitoxantrone, etoposide and cytarabine in relapsed or refractory acute lymphoblastic leukemia

The survival of patients with relapsed or refractory acute lymphoblastic leukemia (ALL) is poor. We performed a retrospective analysis of 40 patients treated with five days of mitoxantrone 8mg/m(2)/day, etoposide 100mg/m(2)/day, and cytarabine 1000mg/m(2)/day (MEC). The complete remission rate was 30% and median remission duration was 11.2 months. Median overall survival was 6.5 months. In univariate analysis, patients in first relapse had improved overall survival compared to ≥second relapse (p=0.02). Thirty-day mortality rate was 7.5%. In relapsed or refractory ALL, MEC demonstrated moderate activity, but did not improve survival compared to published salvage chemotherapy regimens.

The myth of the second remission of acute leukemia in the adult

Although the majority of adult patients with both acute lymphoblastic leukemia and acute myelogenous leukemia achieve remission with upfront chemotherapy, many patients still suffer relapse. Often, the strategy is proposed of treating patients with relapsed leukemia into a second remission (CR2) and then proceeding to allogeneic transplantation as the definitive curative approach. However, the long-term outcomes of such a strategy are poor: the 5-year overall survival from first relapse for patients with acute leukemia is only approximately 10%. This Perspective highlights the fact that most patients do not achieve CR2 and therefore never really have an opportunity for a potential curative therapy. Although patients who undergo transplantation after relapse may be cured, those who do not achieve CR2 are rarely candidates for transplantation; therefore, the overall outcome for patients who relapse is dismal. There is therefore an urgent need not only for more effective upfront therapy to prevent relapse, but also for the development of therapies that can serve as effective bridging treatments between relapse and transplantation. We suggest that more optimal use of minimal residual disease detection during first remission may also improve the chances for successful transplantation therapy via earlier reinduction therapy, allowing transplantation before overt relapse.

Outcome of relapsed adult lymphoblastic leukemia depends on response to salvage chemotherapy, prognostic factors, and performance of stem cell transplantation

Despite improvements in first-line therapies, published results on the treatment of relapsed adult acute lymphoblastic leukemia (ALL) show that prognosis is still poor. The aim of the present retrospective analysis of the German Multicenter Study Group for Adult ALL was to identify prognostic factors and options for improvement. A total of 547 patients with a median age of 33 years (range, 15-55) experiencing their first relapse (406 vs 141 shorter or longer than 18 months from diagnosis) were evaluated. The aim of salvage therapy was to achieve a complete remission (CR) with subsequent a stem cell transplantation (SCT). The CR rate (assessed in Philadelphia chromosome- and BCR-ABL-negative ALL without CNS involvement) after the first salvage in relapse after chemotherapy (n = 224) was 42%. After failure of first salvage (n = 82), the CR rate after second salvage was 33%. In relapse after SCT (n = 48) the CR rate after first salvage was 23%. The median overall survival after relapse was 8.4 months and survival was 24% at 3 years. Prognostic factors for survival were relapse localization, response to salvage, performance of SCT, and age. Overall survival appeared superior compared with previously published studies, likely because of the high rate of SCT in the present study (75%). Further improvement may be achieved with earlier relapse detection and experimental approaches in early relapse.

Outcome after relapse of acute lymphoblastic leukemia in adult patients included in four consecutive risk-adapted trials by the PETHEMA Study Group

BACKGROUND

About one half of adults with acute lymphoblastic leukemia are not cured of the disease and ultimately die. The objective of this study was to explore the factors influencing the outcome of adult patients with relapsed acute lymphoblastic leukemia.

DESIGN AND METHODS

We analyzed the characteristics, the outcome and the prognostic factors for survival after first relapse in a series of 263 adult patients with acute lymphoblastic leukemia (excluding those with mature B-cell acute lymphoblastic leukemia) prospectively enrolled in four consecutive risk-adapted PETHEMA trials.

RESULTS

The median overall survival after relapse was 4.5 months (95% CI, 4-5 months) with a 5-year overall survival of 10% (95% CI, 8%-12%); 45% of patients receiving intensive second-line treatment achieved a second complete remission and 22% (95% CI, 14%-30%) of them remained disease free at 5 years. Factors predicting a good outcome after rescue therapy were age less than 30 years (2-year overall survival of 21% versus 10% for those over 30 years old; P<0.022) and a first remission lasting more than 2 years (2-year overall survival of 36% versus 17% among those with a shorter first remission; P<0.001). Patients under 30 years old whose first complete remission lasted longer than 2 years had a 5-year overall survival of 38% (95% CI, 23%-53%) and a 5-year disease-free survival of 53% (95% CI, 34%-72%).

CONCLUSIONS

The prognosis of adult patients with acute lymphoblastic leukemia who relapse is poor. Those aged less than 30 years with a first complete remission lasting longer than 2 years have reasonable possibilities of becoming long-term survivors while patients over this age or those who relapse early cannot be successfully rescued using the therapies currently available.

Allogeneic SCT in refractory or relapsed adult ALL is effective without prior reinduction chemotherapy

We present 60 patients with refractory (n=8) or relapsed (n=52) adult ALL who received allogeneic hematopoietic SCT (HSCT) with (n=41) or without (n=19) prior reinduction chemotherapy. In our center, omission of reinduction is recommended if a suitable donor is promptly available, tumor burden is moderate and disease features suggest a highly aggressive course. Overall survival (OS) of the whole cohort at 1, 2 and 5 years was 42, 33 and 28%, respectively. Leukemia-free survival at 1, 2 and 5 years was 37, 33 and 24%. Deaths were due to relapse (n=25), acute or chronic GVHD (n=7), infections (n=8) or toxicity (n=4). Interestingly, patients who did not receive reinduction before HSCT had better outcomes than patients who received reinduction with OS at 1, 2 and 5 years being 58 vs 34%, 47 vs 25% and 47 vs 18%, respectively (P=0.039). Importantly, even achievement of a second CR after reinduction was not associated with improved survival compared to patients directly proceeding to HSCT. We conclude that patients who undergo HSCT for refractory or relapsed ALL can achieve long-term survival. In selected patients, reinduction chemotherapy can be omitted if immediate HSCT is feasible.

Transplant-finalized salvage of adult acute lymphoblastic leukemia: results of a mitoxantrone- and methotrexate-based regimen in 36 patients

Idarubicin-based induction programs in acute lymphoblastic leukemia (ALL) account for 75?-?85% of complete remission rate. A small amount of patients exhibit primary refractoriness, and approximately 60% of those achieving a remission eventually relapse. The present study aimed to review the outcome of patients relapsing after or resistant to an idarubicin-based, induction-consolidation regimen (with/without additional high dose cytarabine). The 'ABC' phase II trial consisted of mitoxantrone (50 mg/m(2) over 5 days) associated with high-dose methotrexate (1.5 g/m(2) over 24 h, followed by folinic acid rescue), high-dose methyl-prednisolone (125 mg b.i.d.) and vincristine, plus granulocyte colony-stimulating factor. Eligible patients were treated with two courses ('A' and 'B', the latter with reduced drug dosages), followed by allogeneic or autologous haematopoietic stem cell transplantation (HSCT, 'C'). Thirty-six patients (3 primary resistant, 33 at first marrow relapse) were evaluated. With 'A', 21 achieved a complete remission (CR), 10 were refractory and 5 died early. Eighteen patients received 'B' (with one more CR, for an overall CR rate of 61%) and, eventually, 12 patients had 'C' procedures (7 autologous, 5 allogeneic HSCT). WHO grade >or=3 treatment-related toxicity developed in 50% and 34% of 'A' and 'B' courses, respectively. The median duration of CR was 5.2 (range 0.5-19.7) months and median overall survival was 7.6 (range 0.5-20) months. In spite of 12 HSCTs, there was no long-term survivor. 'ABC' salvage proved feasible and comparable to reported rescue chemotherapic regimens, but the achievement of cure in refractory/relapsing ALL remains an outstanding clinical task.

Long-term outcomes of adults with acute lymphoblastic leukemia after autologous or unrelated donor bone marrow transplantation: a comparative analysis by the National Marrow Donor Program and Center for International Blood and Marrow Transplant Research

For adults with high-risk or recurrent ALL who lack a suitable sibling donor, the decision between autologous (Auto) and unrelated donor (URD) hematopoietic stem cell transplantation (HSCT) is difficult due to variable risks of relapse and treatment-related mortality (TRM). We analysed data from two transplant registries to determine outcomes between Auto and URD HSCT for 260 adult ALL patients in first (CR1) or second (CR2) CR. All patients received a myeloablative conditioning regimen. The median follow-up was 77 (range 12-170) months. TRM at 1 year post transplant was significantly higher with URD HSCT; however, there were minimal differences in TRM according to disease status. Relapse was higher with Auto HSCT and was increased in patients transplanted in CR2. Five-year leukemia-free (37 vs 39%) and overall survival (OS) rates (38 vs 39%) were similar for Auto HSCT vs URD HSCT in CR1. There were trends favoring URD HSCT in CR2. The long-term follow-up in this analysis demonstrated that either Auto or URD HSCT could result in long-term leukaemia-free survival and OS for adult ALL patients. The optimal time (CR1 vs CR2) and technique to perform HSCT remains an important clinical question for adult ALL patients.

How I treat acute lymphocytic leukemia in adults

The treatment of newly diagnosed acute lymphocytic leukemia (ALL) in adults remains unsatisfactory. Not withstanding the outstanding progress in curing childhood ALL, only approximately one third of adults younger than 60 years can be cured, and the overall published survival curves have not changed significantly during the past 15 years. Recent therapeutic advances in allogeneic transplantation through the conduct of large collaborative studies, better understanding of the relevance of cytogenetics, improved molecular techniques for the detection of minimal residual disease, and clinical research into novel biologic and targeted therapies have all combined to offer potentially a better hope for an improved outcome in this disease. The current approach in 2007 to the management of this disease is presented by way of a discussion of illustrative cases. In this uncommon and difficult disease, well-structured intergroup studies will remain vital for future progress.

Nelarabine induces complete remissions in adults with relapsed or refractory T-lineage acute lymphoblastic leukemia or lymphoblastic lymphoma: Cancer and Leukemia Group B study 19801

Nelarabine (506U78) is a soluble pro-drug of 9-beta-D-arabinofuranosylguanine (ara-G), a deoxyguanosine derivative. We treated 26 patients with T-cell acute lymphoblastic leukemia (T-ALL) and 13 with T-cell lymphoblastic lymphoma (T-LBL) with nelarabine. All patients were refractory to at least one multiagent regimen or had relapsed after achieving a complete remission. Nelarabine was administered on an alternate day schedule (days 1, 3, and 5) at 1.5 g/m(2)/day. Cycles were repeated every 22 days. The median age was 34 years (range, 16-66 years); 32 (82%) patients were male. The rate of complete remission was 31% (95% confidence interval [CI], 17%, 48%) and the overall response rate was 41% (95% CI, 26%, 58%). The principal toxicity was grade 3 or 4 neutropenia and thrombocytopenia, occurring in 37% and 26% of patients, respectively. There was only one grade 4 adverse event of the nervous system, which was a reversible depressed level of consciousness. The median disease-free survival (DFS) was 20 weeks (95% CI, 11, 56), and the median overall survival was 20 weeks (95% CI, 13, 36). The 1-year overall survival was 28% (95% CI, 15%, 43%). Nelarabine is well tolerated and has significant antitumor activity in relapsed or refractory T-ALL and T-LBL.

High-dose idarubicin in combination with Ara-C in patients with relapsed or refractory acute lymphoblastic leukemia: a pharmacokinetic and clinical study

OBJECTIVE

High dose (HD) Ara-C combined with a single HD idarubicin dose (IDA) is an efficient and safe salvage regimen for patients with refractory or relapsed acute lymphoblastic leukemia as indicated by phase II studies. No data are available on the pharmacokinetics of IDA after a rapid HD intravenous infusion. An open phase II pharmacokinetic and clinical study was performed to evaluate antileukemic efficacy, IDA pharmacokinetics and to investigate the presence of IDA and its reduced metabolite idarubicinol (IDAol) in cerebrospinal fluid (CSF) of patients treated with HD-IDA.

PATIENTS AND METHODS

Twenty-five patients with refractory or relapsed acute lymphoblastic leukemia received Ara-C 3 g/m2 from days 1-5, idarubicin (HD-IDA) 40 mg/m2 as rapid intravenous (i.v.) infusion on day 3 and subcutaneous G-CSF 5 microg/kg from day 7 until PMN recovery. Pharmacokinetics of IDA was evaluated after HD idarubicin administration in nine of these patients. CSF samples were collected in 15 patients at different times. IDA and IDAol concentrations were quantified by a validated HPLC assay described in detail elsewhere.

RESULTS

Eleven patients (44%, 95% CI: 23-65%) achieved complete remission with median disease free survival for 6 months. After administration of HD-IDA i.v. bolus of 40 mg/m2, plasma level profiles of unchanged drug and IDAol were similar to those previously described after standard dose and measured with the same analytical method. The mean terminal half-life measured for IDA in this group of patients (14.9 h) was not significantly different from the mean value observed after standard dose (13.9 h, P=0.72). IDAol t1/2 was also similar after HD-IDA (46.2 h) and standard dose (39.4 h, P=0.79). Pharmacokinetic data reveal that in our series of patients IDA and IDAol clearances are significantly higher than those observed in patients treated with 12 mg/m2 of IDA but, although the administered dose (mg/m2) of the drug is 3.3 times higher, IDA exposure (measured in terms of AUC) is only 2.3 times and IDAol exposition 2.1 times greater. Furthermore, HD infusion resulted in a ratio between the AUC of parent drug and idarubicinol not different from the value observed with the standard-dose. IDA and IDAol were measurable only in 3 of the 15 cerebrospinal fluid samples collected.

CONCLUSION

Responses observed in our series are comparable to those reported with other salvage regimens. The IDA exposure lower than expected may explain the safety of the single i.v. administration of 40 mg/m2 of IDA, combined with HD Ara-C, with a degree of myelosuppression equivalent to that reported with this agent administered in standard doses. Our data do not allow us to clearly attribute this behavior to a pharmacokinetic non-linearity since the baseline creatinine clearance, even within normal values, and patient age are significantly different in the two groups. Cerebrospinal fluid penetration was poor, reaching levels not considered as cytotoxic.

Outcome of 609 adults after relapse of acute lymphoblastic leukemia (ALL); an MRC UKALL12/ECOG 2993 study

Most adults with acute lymphoblastic leukemia (ALL) who achieve complete remission (CR) will relapse. We examined the outcome of 609 adults with recurring ALL, all of whom were previously treated on the Medical Research Council (MRC) UKALL12/ECOG2993 study, where the overall survival (OS) of newly diagnosed patients is 38% (95% confidence interval [CI]=36%-41%) at 5 years. By contrast, OS at 5 years after relapse was 7% (95% CI=4%-9%). Factors predicting a good outcome after salvage therapy were young age (OS of 12% in patients younger than 20 years vs OS of 3% in patients older than 50 years; 2P<.001) and short duration of first remission (CR1) (OS of 11% in those with a CR1 of more than 2 years versus OS of 5% in those with a CR1 of less than 2 years; 2P<.001). Treatment received in CR1 did not influence outcome after relapse. In a very highly selected subgroup of patients who were able to receive HSCT after relapse, some were long-term survivors. We conclude from a large, unselected series with mature follow-up that most adults with recurring ALL, whatever their prior treatment, cannot be rescued using currently available therapies. Prevention of recurrence is the best strategy for long-term survival in this disease.

Efficacy of liposomal daunorubicin and cytarabine as reinduction chemotherapy in relapsed acute lymphoblastic leukaemia despite expression of multidrug resistance-related proteins

The treatment of relapsed adult acute lymphoblastic leukaemia (ALL) is frequently unsuccessful with current chemotherapy regimens, and often there is an overexpression of multidrug resistance (MDR)-related proteins. Liposomal encapsulation makes daunorubicin (DNR) less sensitive to the efflux effect of P-glycoprotein (PGP), and in vitro data indicate that liposomal-encapsulated DNR (Daunoxome-DNX) is more toxic than DNR against ALL cell lines. In this study, we assessed the in vivo and in vitro efficacy and toxicity of DNX plus cytarabine (Ara-C) as reinduction chemotherapy in 25 relapsed ALL patients (pts). The expression of MDR-related proteins (PGP, MRP1 and LRP) was also analysed. Of the 25 pts, 12 were males and 13 females; median age was 32 yr (range 18-58). Six cases were ALL T and 19 ALL B; eight pts were Ph+ (32%), and nine Bcr-Abl+ (36%). The expression of MDR-related proteins, and DNR and DNX retention and induction of apoptosis in leukaemic cells were evaluated in all cases. Seventeen of 25 (68%) pts were at first relapse and eight (32%) at second or subsequent relapse. The DNX was given in a dose of 80 mg/m(2)/d (days 1-3) in 11/25 pts (44%) and in a dose of 100 mg/m(2)/d (days 1-3) in 14/25 pts (66%). In all pts, Ara-C was administered in a dose of 2 g/m(2) (days 1-5). Twenty pts (80%) achieved a complete remission (CR) and two (8%) entered a partial remission (PR) for an overall response (OR) rate of 88% (22/25), with a tolerable toxicity and without significant cardiotoxicity. Before the start of DNX therapy, 18/25 (72%) cases overexpressed at least one MDR-related protein compared with 9/25 (36%) cases with MDR overexpression at diagnosis (P = 0.01). Taking into account the small number of cases, the response rate was not affected by MDR expression and the in vitro results also showed a higher uptake and apoptotic cell death by DNX compared with DNR. Twelve pts subsequently underwent allogeneic bone marrow transplantation (11 unrelated donor BMT, and one sibling BMT). The overall survival was 39% after 12 months. These data show the efficacy (OR rate 88% and CR rate 80%) of DNX plus Ara-C as reinduction therapy in very poor-risk ALL pts and the response rate seems not to be affected by MDR overexpression. Moreover, the high rate of remissions and the good clinical tolerance in heavily pretreated pts suggest a promising role of DNX in ALL chemotherapy regimens.

Adult acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) in adults is a relatively rare neoplasm with a curability rate around 30% at 5 years. This consideration makes it imperative to dissect further the biological mechanisms of disease, in order to selectively implement an hitherto unsatisfactory success rate. The recognition of discrete ALL subtypes (some of which deserve specific therapeutic approaches, like T-lineage ALL (T-ALL) and mature B-lineage ALL (B-ALL)) is possible through an accurate combination of cytomorphology, immunophenotytpe and cytogenetic assays and has been a major result of clinical research studies conducted over the past 20 years. Two-three major prognostic groups are now easily identifiable, with a survival probability ranging from <10 to 20% (Philadelphia-positive ALL) to about 50-60% (low-risk T-ALL and selected patients with B-lineage ALL). These issues are extensively reviewed and form the basis of current knowledge. The second major point relates to the emerging importance of studies that reveal a dysregulated gene activity and its clinical counterpart. It is now clear that prognostication is a complex matter ranging from patient-related issues to cytogenetics to molecular biology, including the evaluation of minimal residual disease (MRD) and possibly gene array tests. On these bases, the role of a correct, highly personalised therapeutic choice will soon become fundamental. Therapeutic progress may be obtainable through a careful integration of chemotherapy, stem cell transplantation, and the new targeted treatments with highly specific metabolic inhibitors and humanised monoclonal antibodies.

Autologous stem cell transplantation and purging in adult acute lymphoblastic leukaemia

The prognosis for adult acute lymphoblastic leukaemia (ALL) is poor. Only 20-30% of patients will be cured with conventional chemotherapy. Haematopoietic progenitor transplantation is thus an attractive option in these patients. Even if allogeneic transplantation allows a better control of the disease, autologous transplantation remains an important alternative for patients lacking a suitable donor or when allogeneic transplants imply excessive risk. Relapse is the main drawback of autologous transplants, but many strategies are being explored to overcome this problem. We focus here on transplant modality, the source of haematopoietic progenitors, and the best timing to apply the procedure. Also reviewed are the current situation and future strategies for improving results in this setting, such as ex vivo purging; immunotherapy and maintenance chemotherapy.

A single, high dose of idarubicin combined with cytarabine as induction therapy for adult patients with recurrent or refractory acute lymphoblastic leukemia

BACKGROUND

The majority of adult patients who are treated for lymphoblastic disease will either develop recurrent disease or will be refractory to their initial therapy. One option for patients with recurrent/refractory disease is to administer a reinduction regimen that employs a dose-intense combination of anthracycline and cytarabine. These salvage regimens are relatively distinct from the traditional vincristine/prednisone-based programs that are used typically as primary induction therapy. The authors studied a regimen that contained high-dose cytarabine and a single high dose of idarubicin as salvage induction therapy for patients with recurrent or refractory lymphoblastic disease.

METHODS

Twenty-nine previously treated adult patients with recurrent or refractory acute lymphoblastic leukemia were treated with a new intensive regimen. Eight patients had primary refractory disease. Twenty-one patients had recurrent disease, and 16 of these patients developed recurrent disease while they were still receiving their primary therapy. The treatment regimen consisted of cytarabine 3.0 g/m(2) by 3-hour infusion daily for 5 days and idarubicin 40 mg/m(2) given as a single dose on Day 3. Filgrastim (granulocyte-colony stimulating factor) 5 microg/kg administered subcutaneously every 12 hours was started on Day 7 and was continued until the absolute neutrophil count was > 5000/microL. Response was assessed using standard criteria.

RESULTS

There were 11 complete responses (38%; 95% confidence interval, 20-56%). Four patients subsequently underwent allogeneic bone marrow transplantation. Moderate but acceptable toxicity was observed given the severely myelosuppressive nature of the regimen. There was only one treatment-related death (3%). Two patients, both with significant prior exposure to anthracyclines, suffered reductions in left ventricular function to the 20-30% range during episodes of severe systemic infection. After recovery from infection, the ejection fraction in one patient improved to 50%.

CONCLUSIONS

The authors conclude that this regimen has moderate activity and a relatively low incidence of mortality for this high-risk group of patients. This regimen may be most suitable for patients who can undergo potentially curative allogeneic bone marrow transplantation if they achieve a complete response.

Minimal residual disease tests provide an independent predictor of clinical outcome in adult acute lymphoblastic leukemia

PURPOSE

Investigation of minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL) using molecular markers has proven superior to other standard criteria (age, sex, and WBC) in distinguishing patients at high, intermediate, and low risk of relapse. The aim of our study was to determine whether MRD investigation is valuable in predicting outcome in Philadelphia-negative adult patients with ALL.

PATIENTS AND METHODS

MRD was assessed in 85 adult patients with B-lineage ALL by semiquantitative immunoglobulin H gene analysis on bone marrow samples collected during four time bands in the first 24 months of treatment. Fifty patients received chemotherapy only and 35 patients received allogeneic (n = 19) or autologous (n = 16) bone marrow transplantation (BMT) in first clinical remission. The relationship between MRD status and clinical outcome was investigated and compared with age, sex, immunophenotype, and presenting WBC count.

RESULTS

Fisher's exact test established a statistically significant concordance between MRD results and clinical outcome at all times. Disease-free survival (DFS) rates for MRD-positive and -negative patients and log-rank testing established that MRD positivity was associated with increased relapse rates at all times (P <.05) but was most significant at 3 to 5 months after induction and beyond. MRD status after allogeneic BMT rather than before was found to be an important predictor of outcome in 19 adult patients with ALL tested. In patients receiving autologous BMT (n = 16), the MRD status before BMT was more significant (P =.005).

CONCLUSION

The association of MRD test results and DFS was independent of and greater than other standard predictors of outcome and is therefore important in determining treatment for individual patients.

Salvage therapy for refractory or relapsed acute lymphocytic leukemia

The overall prognosis for patients with relapsed or refractory adult ALL remains poor. Further insight into the biology of ALL is required, and novel therapeutic agents are needed to counter mechanisms of resistance. A palliative approach to the management of multiply relapsed or refractory ALL should be supplanted by enrollment into clinic trials to promote drug discovery. Monitoring of minimal residual disease may allow an earlier intervention before overt clinical relapse and improve outcome; prospective studies are needed. Attainment of a second or later CR should be followed by allogeneic BMT when feasible owing to the paucity of long-term survivors with salvage chemotherapy alone.

Primary refractory and relapsed adult acute lymphoblastic leukemia: characteristics, treatment results, and prognosis with salvage therapy

BACKGROUND

Relapses continue to be problematic for adults with acute lymphoblastic leukemia (ALL). New therapies generally are first tested in the salvage setting prior to incorporation into frontline regimens. Defining the prognosis at relapse (or at failure of induction) and subsequently predicting outcome would be useful to select the population in whom to test new strategies, rather than attempting traditional reinduction therapy.

METHODS

Between March 1980 and March 1997, 314 eligible adults with primary refractory (24%) or primary relapsed (76%) ALL were treated with various chemotherapy or stem cell transplantation (SCT) regimens. The Cox proportional hazards model was used to assess biologic factors and disease history in relation to survival.

RESULTS

A complete remission (CR) was achieved in 97 patients (31%), 21% died prior to a response, and 49% were refractory to salvage therapy. Of the 76 patients refractory to induction therapy for their de novo ALL, 26 patients (34%) achieved a CR with salvage therapy. The median overall CR duration was 6 months. The median overall survival was 5 months; 24% of the patients were alive at 1 year, and the projected survival at 5 years was 3%. Nineteen patients were alive at the time of last follow-up, 10 with 6 weeks to 10 years of continuous CR from the time of their first salvage therapy. SCT consolidation in second CR was performed in 25% of patients; 28% of those who received allogeneic SCT remain in continuous CR at 4 months, 2(1/2) years, 3(1/2) years, and 10 years, whereas all 8 who received autologous SCT have relapsed. Favorable factors for longer survival by multivariate analysis were age <40 years, absence of circulating blasts, and first CR duration longer than 1 year. Patients were stratified into 4 risk groups: Group 1, with no unfavorable features or only short initial CR duration; Group 2, with only increased age or peripheral blasts; Group 3, with any 2 unfavorable features; and Group 4, with all 3 unfavorable features. The median survival times for each group were 11, 6, 4, and 2 months, respectively; 1-year survival rates were 44%, 25%, 12%, and 9%, respectively (P < 0.01). The resulting model was also predictive for CR rates; the corresponding CR rates were 47%, 35%, 14%, and 9%, respectively (P < 0.01).

CONCLUSIONS

Salvage therapy for adult ALL patients continues to yield poor results, but it is an area of research where it may be possible to discover new agents or strategies to be incorporated into frontline therapy. The prognostic model derived will be utilized prospectively to select patients for new therapeutic strategies involving such novel agents as liposomal compounds, purine nucleoside phosphorylase inhibitors, and monoclonal antibodies.