Light Chain-Predominant Multiple Myeloma Subgroup: Impaired Renal Function Correlates with Decreased Survival.

OBJECTIVE: Patients with light chain-predominant multiple myeloma have been shown to exhibit shorter survival. Retrospective comparison of clinical and laboratory data was undertaken to ascertain the likely cause(s) of this observation. METHODS: Records of patients with multiple myeloma seen at 1 institution revealed 316 patients with conventional and 71 patients with light chain-predominant multiple myelomas with secretion of intact immunoglobulins. Laboratory and clinical findings in the 2 groups were compared. RESULTS: Patients with light chain-predominant multiple myeloma had a significantly higher death rate, a higher rate of chronic dialysis, a lower estimated glomerular filtration rate and serum albumin, a significantly higher urine protein concentration, and a significantly higher prevalence of hypertension and blood transfusion requirements. Other clinical and laboratory parameters surveyed were not significantly different between the 2 groups. CONCLUSION: The shorter survival of patients with light chain-predominant multiple myeloma is clearly associated with renal damage caused by excess free immunoglobulin light chains. Renal damage may be ameliorated by early aggressive treatment with chemotherapy, plasmapheresis, and dialysis; a multi-institutional prospective controlled trial would be needed to test this hypothesis.

Comanagement Strategy Between Academic Institutions and Community Practices to Reduce Induction Mortality in Acute Promyelocytic Leukemia.

PURPOSE: Acute promyelocytic leukemia (APL) is a curable leukemia with > 90% survival in clinical trials. Population-based studies from Sweden and US SEER data have shown long-term survival rates of 62% and 65.7%, with the lower rate being from a higher percentage of early deaths. METHODS: In this prospective, multicenter trial, we developed a simplified algorithm that focused on prevention and early treatment of the three main causes of death: bleeding, differentiation syndrome, and infection. All patients with a diagnosis of APL were included. The initial 6 months were spent educating oncologists about early deaths in APL. At the time of suspicion of an APL, an expert was contacted. The algorithm was made available followed by discussion of the treatment plan. Communication between expert and treating physician was frequent in the first 2 weeks, during which time most deaths take place. RESULTS: Between September 2013 and April 2016, 120 patients enrolled in the study from 32 hospitals. The median age was 52.5 years, with 39% > 60 years and 25% with an age-adjusted Charlson comorbidity index > 4. Sixty-three percent of patients were managed at community centers. Two patients did not meet the criteria for analysis, and of 118 evaluable patients, 10 died, with an early mortality rate of 8.5%. With a median follow-up of 27.3 months, the overall survival was 84.5%. CONCLUSION: Induction mortality can be decreased and population-wide survival improved in APL with the use of standardized treatment guidelines. Support from experts who have more experience with induction therapy is crucial and helps to improve the outcomes.

Optimizing management of acute leukemia in community centers and when to refer.

Treatment of acute leukemia has been delivered predominantly in academic and larger leukemia treatment centers with the infrastructure and staff needed to manage patients receiving complex therapeutic regimens and supportive care. However, in recent years, several oral agents and less-myelosuppressive regimens were approved, making it possible for these patients to receive therapy in smaller community hospitals and oncology office practices. In this review, we discuss the optimum community setting, type of patient who can be treated, agents that can be applied, and an appropriate clinical circumstance in which a referral to a tertiary center should be made.

Lenalidomide-Associated Immune Thrombocytopenia: A Case Report and Review of the Literature.

Lenalidomide is indicated in the front-line management of multiple myeloma. More recently, it has been introduced for use in treating other hematologic malignancies. Although the drug is known to cause myelosuppression, there have been rare reports of lenalidomide-associated immune thrombocytopenia (ITP). Here, we review the literature on lenalidomide-associated ITP and report upon a 59-year-old man who was administered lenalidomide due to concern of progressive multiple myeloma more than a year following his having undergone an autologous hematopoietic stem cell transplant. His platelet count precipitously declined and lead to his hospitalization. Despite our withholding of the drug, he did not respond to platelet transfusions or administration of corticosteroids. He was successfully managed with intermittent immune globulin for several months before definitive treatment with splenectomy, which resulted in the complete resolution of his thrombocytopenia. A literature search identified a total of six additional cases of lenalidomide-associated ITP. Similarly, many of the reported cases were associated with persistent thrombocytopenia after discontinuation of the drug. Furthermore, these patients were generally managed successfully with standard ITP therapies, such as corticosteroids or intravenous immune globulin.

Role of indoleamine 2,3-dioxygenase in acute myeloid leukemia.

Indoleamine 2,3 dioxygenase (IDO), first discovered in the 1960s, is an enzyme that has become a highly investigated metabolic target in cancer research. IDO is the rate-limiting step in tryptophan metabolism catabolism into its byproducts - kynurenines. Both IDO and kynurenines have been implicated in altering the tumor microenvironment, allowing for a tolerogenesis by affecting T-cell maturation and proliferation, and more specifically by inducing differentiation into T regulatory cells. Two mechanisms have been suspected in creating this environment: tryptophan starvation and metabolite toxicity. IDO has been shown to be expressed not only in cancer cells but also in antigen-presenting cells. The exact mechanisms underlying the two different sites of expression have not been fully elucidated. To date, most literature has focused on the role of IDO in solid tumors; we provide a review of IDO and its impact on hematological malignancies - more specifically, acute myeloid leukemia. The pathophysiology of IDO will be discussed, including a summarization of the literature to date on how IDO expression effects prognosis and disease progression in acute myeloid leukemia, along with current IDO-specific therapeutics with future considerations.

Availability of all-trans retinoic acid and support systems for management of acute promyelocytic leukemia in Michigan and Louisiana, USA.

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia with high induction mortality in the general population despite evidence of high cure rates in the clinical trials. Aggressive supportive care is essential for ideal management of these patients. We conducted a survey to collect data on these important issues required for successful treatment/outcome of APL patients from two states (Michigan and Louisiana) due to their low one-year survival rate among the Surveillance, Epidemiology, and End Results registries. All eligible hospitals (253) were obtained from the Data Medicare online directory. Availability of ATRA, formulary process to obtain it, blood back availability and established treatment protocols for the management of APL patients were queried. Since most of the hospitals surveyed do not have a treatment protocol, we believe that outcome could be improved if a standardized and simplified set of treatment and supportive care guidelines are developed for all hospitals treating APL.

A phase 1 trial of vadastuximab talirine combined with hypomethylating agents in patients with CD33-positive AML.

Treatment of acute myeloid leukemia (AML) among the elderly is challenging because of intolerance of intensive therapy and therapy-resistant biology. Hypomethylating agents (HMAs) are commonly used, with suboptimal outcomes. Vadastuximab talirine is a CD33-directed antibody conjugated to pyrrolobenzodiazepine (PBD) dimers. Preclinically, HMAs followed by vadastuximab talirine produced upregulated CD33 expression, increased DNA incorporation by PBD, and enhanced cytotoxicity. A combination cohort in a phase 1 study (NCT01902329) assessed safety, tolerability, and activity of vadastuximab talirine with HMAs. Those eligible had Eastern Cooperative Oncology Group status 0 to 1 and previously untreated CD33-positive AML, and declined intensive therapy. Vadastuximab talirine was administered intravenously at 10 µg/kg on last day of HMA (azacitidine or decitabine) infusion in 4-week cycles. Among 53 patients treated, the median age was 75 years. Patients had adverse (38%) or intermediate (62%) cytogenetic risk. Median treatment duration was 19.3 weeks. No dose-limiting toxicities were reported. The majority of adverse events were a result of myelosuppression, with some causing therapy delays. Thirty- and 60-day mortality rates were 2% and 8%, respectively. The composite remission rate (complete remission [CR] and CR with incomplete blood count recovery) was 70%. Fifty-one percent of remissions were minimal residual disease-negative by flow cytometry. Similarly high remission rates were observed in patients with secondary AML, aged at least 75 years, and with adverse cytogenetic risk. Median relapse-free survival and overall survival were 7.7 and 11.3 months, respectively. Compared with historical data for HMA monotherapy, the combination of vadastuximab talirine with HMAs produced a high remission rate, but was accompanied by increased hematologic toxicity.

Ruxolitinib: a steroid sparing agent in chronic graft-versus-host disease.

Inhibition of the Janus-associated kinases (JAK) with ruxolitinib (RUX) reduces graft-versus-host disease (GVHD) in preclinical and clinical models. In total 19 allograft recipients with moderate/severe steroid-dependent chronic GVHD received RUX as ≥2nd line salvage. RUX was well tolerated, and led to complete/partial resolution of oral (92/7%), cutaneous (82/0%), hepatic (71/28%), gastro-intestinal (75/17%), musculoskeletal (33/67%), pulmonary (0/80%), scleroderma (0/75%), vaginal (0/75%), and ocular (0/100%) chronic GVHD. Overall 18 achieved partial response and 1 complete response according to NIH Consensus Criteria. Responses occurred early and were sustained which enabled discontinuation (68%) or reduction of steroids to physiologic doses (21%). We conclude that RUX is an effective steroid-sparing agent in chronic GVHD.

A phase 1 trial of vadastuximab talirine as monotherapy in patients with CD33-positive acute myeloid leukemia.

Vadastuximab talirine (SGN-CD33A, 33A) is an antibody-drug conjugate consisting of pyrrolobenzodiazepine dimers linked to a monoclonal antibody targeting CD33, which is expressed in the majority of acute myeloid leukemia (AML) patients. This phase 1 study evaluated the safety, pharmacokinetics, and preliminary activity of vadastuximab talirine and determined the recommended monotherapy dose in patients with relapsed or refractory AML. Additional expansion cohorts tested vadastuximab talirine in specific subpopulations of relapsed AML, and in a cohort of older, treatment-naive patients. Patients received vadastuximab talirine IV on day 1 (5-60 µg/kg) or on days 1 and 4 (20 µg/kg) of 21-day cycles. A total of 131 patients (median age, 73 years [range, 26-89 years]) had intermediate I-II (48%) or adverse (34%) risk by European LeukemiaNet classification; 50% of patients had underlying myelodysplasia. Two dose-limiting toxicities (grade 2 pulmonary embolism and grade 4 hypocellular marrow) occurred during dose finding. Most adverse events (AEs) were consistent with myelosuppression; nonhematologic AEs included fatigue, nausea, and diarrhea. The 30-day mortality was 8%. At the recommended monotherapy dose of 40 µg/kg, the complete remission + CRi rate was 28% (5 of 18 patients); 50% of patients who responded achieved minimal residual disease negativity. In patients across dose levels who achieved CR or CRi, the median time to full count recovery was 6.4 weeks for neutrophils (≥1000/µL) and 10.6 weeks for platelets (≥100 × 109/L). Vadastuximab talirine demonstrates activity and a tolerable safety profile as a single agent in patients with AML. The recommended monotherapy dose of vadastuximab talirine is 40 µg/kg. This trial was registered at www.clinicaltrials.gov as # NCT01902329.

Outcomes of Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia Following an Elective Switch From Second-Generation Tyrosine Kinase Inhibitor to Imatinib.

The second-generation tyrosine kinase inhibitors (TKIs) (2G-TKIs) dasatinib (DAS) and nilotinib (NIL) yield faster responses in newly diagnosed chronic phase (CP) chronic myeloid leukemia (CML) as compared with imatinib (IM); however, long-term safety of these agents is a growing concern. We identified 20 patients with CP-CML diagnosed between August 2013 and October 2016 who initiated 2G-TKIs and were then switched after optimal response at 3 months to IM. Second-generation TKIs initiated were DAS (n = 15), NIL (n = 3), or both sequentially due to intolerance (n = 1). One other patient initiated therapy with ponatinib on trial. Response was assessed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) for BCR-ABL1 levels every 3 months and in patients with qRT-PCR values less than 10% at 3 months, IM was started at 400 mg/d. IM was well tolerated except in 2 patients who required dose-reduction and discontinuation due to grade 2 skin rash (1) and grade 2 anxiety (1). After initiation of IM therapy, the BCR-ABL1 qRT-PCR levels trended down as expected. At 12 months 16 (84.2%) of 19 evaluable patients showed a 3 log (major molecular remission) or better reduction in their PCR levels. In conclusion, this retrospective analysis shows that IM can be safely and effectively administered following optimal response to 2G-TKIs. A prospective trial exploring this approach is currently enrolling and will be needed to confirm the safety and efficacy of this therapeutic approach.

A novel immunohistochemical score to predict early mortality in acute myeloid leukemia patients based on indoleamine 2,3 dioxygenase expression.

Indoleamine 2,3 dioxygenase-1 (IDO-1) is an enzyme in the kynurenine pathway which augments tumor-induced immune tolerance. Previous studies in childhood acute myeloid leukemia (AML) have shown a negative correlation of IDO-1 mRNA expression with outcomes. The aim of our study was to develop a practical and objective immunohistochemical technique to quantify IDO-1 expression on diagnostic bone marrow biopsies of AML patients in order to facilitate its use in routine clinical practice. IDO-1 mRNA was extracted from diagnostic bone marrow specimens from 29 AML patients. IDO-1 protein expression was assessed in 40 cases via immunohistochemistry and quantified by a novel 'composite IDO-1 score'. In a univariate analysis, higher age (p = 0.0018), male gender (p = 0.019), high risk cytogenetics (p = 0.002), higher IDO-1 mRNA (p = 0.005), higher composite IDO-1 score (p < 0.0001) and not undergoing allogeneic stem cell transplant (SCT, p = 0.0005) predicted poor overall survival. In a multivariate model that included the aforementioned variables, higher composite IDO-1 score (p = 0.007) and not undergoing allogeneic SCT (p = 0.007) was found to significantly predict poor outcomes. Further, patients who failed induction had higher composite IDO-1 score (p = 0.01). In conclusion, 'composite IDO-1 score' is a prognostic tool that can help identify a certain subset of AML patients with 'early mortality'. This unique subset of patients can potentially benefit from specific IDO-1 inhibitor therapy, currently in clinical trials.

Does the frequency of molecular monitoring after tyrosine kinase inhibitor discontinuation affect outcomes of patients with chronic myeloid leukemia?

BACKGROUND: To the authors' knowledge, the optimal frequency of monitoring after tyrosine kinase inhibitor (TKI) discontinuation in patients with chronic myeloid leukemia (CML) has not been established. Data regarding the discontinuation of second-generation TKIs used in first-line treatment or after the failure of first-line treatment with TKIs are limited. Herein, the authors report real-world experience with "reduced frequency" molecular monitoring in patients with CML in all phases who discontinued treatment with imatinib, dasatinib, or bosutinib. METHODS: The records of patients who discontinued TKIs were reviewed. Patients who discontinued TKIs were monitored prospectively on an intended schedule of monthly blood quantitative reverse transcriptase-polymerase chain reaction for BCR-ABL1 for 3 months, quarterly for 12 months, and every 6 months thereafter until loss of major molecular response (MMR). After loss of MMR, the TKI that previously was discontinued was reinitiated. RESULTS: Between January 2010 and September 2015, a total of 24 patients in chronic (21 patients), accelerated (2 patients), and lymphoid blast (1 patient) phase discontinued imatinib (16 patients), dasatinib (5 patients), or bosutinib (3 patients) used in the front-line treatment or beyond. Blood quantitative reverse transcriptase-polymerase chain reaction for BCR-ABL1 was performed 1.3 ± 0.7 times within the first 3 months (24 patients) and 2.7 ± 1.4 times in the following 12 months (18 patients). With a median follow-up of 36.5 months (range, 3.2-67.4 months), the probabilities of treatment-free remission at 1 year and 2 years were 65.7% (95% confidence interval, 55.8%-75.6%) and 59.7% (95% confidence interval, 49.1%-70.3%), respectively. Loss of MMR was observed in 9 patients at a median of 2.8 months (range, 1.8-14.2 months) after discontinuation of TKIs. CONCLUSIONS: With the limitations of a small sample size, the results of the current study demonstrate that less frequent monitoring of BCR-ABL1 does not appear to affect outcomes, and that discontinuation of TKIs used as first-line treatment or beyond after resistance or intolerance to first-line treatment appears feasible. Cancer 2017;123:2482-88. © 2017 American Cancer Society.

Exploratory study on the impact of switching to nilotinib in 18 patients with chronic myeloid leukemia in chronic phase with suboptimal response to imatinib.

BACKGROUND: The phase II, exploratory, open-label Exploring Nilotinib BCR-ABL Effects (ENABL) study [ClinicalTrials.gov identifier: NCT00644878] assessed the impact of switching to nilotinib therapy in patients with chronic myeloid leukemia in chronic phase (CML-CP) who had a suboptimal molecular response with imatinib. METHODS: Patients with CML-CP who had previously achieved a complete cytogenetic response (CCyR), but had a suboptimal molecular response, with frontline imatinib therapy (N = 18) were assigned to receive nilotinib 300 mg twice daily. The primary endpoint was the change in BCR-ABL1 transcript levels from baseline after 12 months; rates of major molecular response (MMR) and safety were also assessed. RESULTS: At 3 months after switching to nilotinib, 10 of 17 (59%) evaluable patients had achieved MMR. At 12 months, 9 of 12 (75%) evaluable patients had achieved MMR, and the median BCR-ABL1 level among all patients remaining in the study was 0.020% on the International Scale (IS), equivalent to a 3.7-log reduction from the standardized IS baseline (primary endpoint). Adverse events (AEs) were typically grade 1/2 and manageable with dose interruptions. A total of three patients experienced serious study drug-related AEs, including pancreatitis, bradycardia, and vertigo. No deaths were reported. CONCLUSIONS: Overall, results from this exploratory study suggest that switching to nilotinib due to suboptimal molecular response with imatinib can result in improved molecular response for patients with CML-CP.

Does Post-Transplant Maintenance Therapy With Tyrosine Kinase Inhibitors Improve Outcomes of Patients With High-Risk Philadelphia Chromosome-Positive Leukemia?

INTRODUCTION: The effect of post-transplant maintenance tyrosine kinase inhibitors (TKIs) on the outcomes of allogeneic hematopoietic stem cell transplantation in high-risk Philadelphia chromosome-positive (Ph(+)) leukemia remains unknown. PATIENTS AND METHODS: A retrospective analysis that included allograft recipients with accelerated phase and blast phase chronic myeloid leukemia or Ph(+) acute lymphoblastic leukemia who had received post-transplant maintenance TKI therapy from 2004 to 2014. RESULTS: A total of 26 patients, 9 with accelerated phase/blast phase CML and 17 with Ph(+) acute lymphoblastic leukemia, received maintenance post-transplant therapy with imatinib, dasatinib, nilotinib, or ponatinib. The TKI was selected according to the pretransplantation TKI response, anticipated toxicities, and ABL1 domain mutations, when present. Newer generation TKIs were initiated at a ≥ 50% dose reduction from the standard pretransplantation dosing to limit the toxicities and avoid therapy interruptions. TKIs were started a median of 100 days (range, 28-238 days) after transplantation and were administered for a median of 16 months (range, 8 days to 105 months). Eight patients discontinued therapy because of adverse events. With a median follow-up of 3.6 years (range, 4 months to 8.7 years), the 5-year relapse-free survival rate was 61%. All 3 patients who developed a relapse underwent successful salvage treatment and remained disease-free. The 5-year overall survival rate was 78%. CONCLUSION: Maintenance TKI therapy after transplantation is feasible and might reduce the incidence of relapses and improve outcomes after allogeneic hematopoietic stem cell transplantation for patients with high-risk Ph(+) leukemia.

Predicting early blast transformation in chronic-phase chronic myeloid leukemia: is immunophenotyping the missing link?

BACKGROUND: Flow cytometry (FC) is a commonly requested test in the workup of leukocytosis in community practices. The role of FC in chronic-phase chronic myeloid leukemia (CP-CML) is unknown. We hypothesized that finding aberrant cells with FC in CP-CML may predict early blast-phase (BP) transformation. METHODS: Results for FC performed at the time of diagnosis for adult and pediatric patients with CP-CML who were referred to our institution were reviewed, and they were correlated with outcomes. RESULTS: FC was performed at the time of diagnosis for 110 of 233 patients (47%) with CP-CML. Aberrant populations, representing a median of 2% (range, 0.3%-15%), were detected with FC in 30% of patients (33 of 110): 2 of these 33 patients expressed lymphoid markers, and 31 expressed aberrant myeloid markers. Patients received imatinib (85%), dasatinib (12%), or nilotinib (3%) as their first-line treatment. With a median follow-up of 43 months (range, 2-113 months), chronic myeloid leukemia transformed to BP in 5 of the 33 patients. The 2 patients with lymphoid markers and the 3 of 31 patients with aberrant myeloid markers experienced a transformation to lymphoid BP at a median of 11 months (range, 4-72 months) after the initiation of tyrosine kinase inhibitor therapy. Although both cases with detectable lymphoid markers rapidly progressed to lymphoid BP, the positive predictive value of BP transformation by the detection of myeloid aberrant cells with FC was only 10% (3 of 31). CONCLUSIONS: In contrast to aberrant myeloid markers, the detection of lymphoid markers by FC at the time of the diagnosis of CP-CML appears to be associated with early progression to lymphoid BP.

Congestive heart failure during induction with anthracycline-based therapy in patients with acute promyelocytic leukemia.

BACKGROUND: Acute promyelocytic leukemia (APL) is a highly curable malignancy. However, 30% of patients die during therapy induction from bleeding, differentiation syndrome (DS), and/or infection. Recommendations suggest that congestive heart failure (CHF) is a presenting feature of DS. OBJECTIVE: To assess the incidence of CHF during induction in patients with APL. METHODS: A retrospective chart review was performed of patients diagnosed with APL from December 2004 to July 2013 and managed at Georgia Regents University Cancer Center. Baseline and follow-up ejection fractions (EF) were recorded and patients with a drop in EF during the induction period were evaluated. RESULTS: Of the 40 evaluable patients, 37 received idarubicin-based chemotherapy. 16 of the 37 patients had a repeat ECHO for suspected cardiomyopathy, and 6 of the 16 patients (37.5%) demonstrated a decrease in EF (absolute drop, 10%-35%). The cardiac function recovered completely in 4 patients and partially in 1 patient. Gender, history of hypertension, and body mass index did not seem to correlate with incidence of CHF. LIMITATIONS: The patient population is very small given the rarity of the disease. Present practice patterns do not routinely address CHF in the differential diagnosis. CONCLUSIONS: Patients with APL are at risk for cardiac toxicity for a number of reasons, including cytokine storm and inflammatory state, use of anthracyclines, and DS. The clinical presentation of DS most commonly involves dyspnea and fluid retention, which are also symptoms of heart failure. Prompt cardiac evaluation should be undertaken to rule out CHF in APL patients who are going to receive an anthracycline-based therapy, because early intervention may result in an improved outcome.

Recurrent adult choroid plexus carcinoma treated with high-dose chemotherapy and syngeneic stem cell (bone marrow) transplant.

Choroid plexus carcinomas (CPCs) are rare epithelial central nervous system tumors. CPC occurs mainly in infants and young children, comprising ≈ 1 to 4% of all pediatric brain neoplasms. There is very limited information available regarding tumor biology and CPC treatment due to its rarity. There have been various case reports and meta-analyses of reported cases with CPC. Surgical resection is often challenging but remains a well-established treatment option. Chemotherapy is often reserved for recurrent or refractory cases, but the goal of treatment is usually palliative. We present a case of recurrent, adult CPC with disseminated leptomeningeal involvement treated with salvage chemotherapy including high-dose ifosfamide, carboplatin, and etoposide; once a remission was achieved, this response was consolidated with a syngeneic stem cell (bone marrow) transplant after a preparative regimen of high-dose chemotherapy with carboplatin, etoposide, and thiotepa. Although the patient tolerated the transplant well and remained disease-free for 12 months, she subsequently succumbed to relapsed disease 18 months posttransplant. We believe that this is the first report of using syngeneic stem cell transplant in CPC to consolidate a remission achieved by salvage chemotherapy.

Plerixafor Salvage Is Safe and Effective in Hard-to-Mobilize Patients Undergoing Chemotherapy and Filgrastim-Based Peripheral Blood Progenitor Cell Mobilization.

The combination of filgrastim (G-CSF) and plerixafor is currently approved for mobilizing peripheral blood progenitor cells in patients with non-Hodgkin lymphoma and multiple myeloma undergoing autologous peripheral blood hematopoietic cell transplantation. However, chemotherapy and G-CSF-based mobilization remains a widely used strategy for peripheral blood progenitor cell collection. In this paper we describe our experience from two North American transplant centers in a series of patients who received salvage plerixafor while failing chemotherapy and G-CSF mobilization. Patients received a median of two doses of plerixafor salvage upon failure to mobilize adequate number of peripheral blood progenitor cells at neutrophil recovery. The use of plerixafor was associated with a 2.4-fold increase in peripheral blood CD34+ cell count and 3.9-fold increase in total CD34+ cell yield. All patients were able to collect ≥2 × 10(6) CD34+ cells/kg with this approach. These results were more pronounced in patients with a higher CD34+ cell count at the time of the first plerixafor dose. Interestingly, peripheral blood white blood cell count was not shown to correlate with a response to plerixafor. Our results provide safety and efficacy data for the use of plerixafor in patients who are destined to fail chemomobilization.