Minimal Residual Disease Response Research Articles

Initial Results from a Phase 2 Study of Blinatumomab in Pediatric Patients with Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia

▪Introduction: Acute lymphoblastic leukemia (ALL) is the most common malignant disease in childhood. Patients (pts) with relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) and/or multiple prior salvage therapies and/or refractory disease have a particularly poor prognosis. Blinatumomab is an investigational bispecific T-cell engager (BiTE®) antibody construct that redirects T cells to CD19+ B cells resulting in serial lysis. In phase 2 clinical studies, blinatumomab has demonstrated antitumor activity in adults with relapsed/refractory non-Hodgkin lymphoma and ALL. We evaluated efficacy and toxicity of blinatumomab in pediatric pts with relapsed/refractory ALL who have a particularly poor prognosis.Methods: Eligible pts were 2-18 years of age and had B-cell precursor ALL that was refractory, in ≥2nd bone marrow relapse, or in any marrow relapse after alloHSCT. This was a multicenter, open-label study using a Simon 2-stage design with a phase 1 and a phase 2 part. In the phase 1 part, a stepwise dose of 5→15 µg/m²/day was established as the recommended phase 2 dose (von Stackelberg et al. Blood. 2013;122:70). Blinatumomab was given by continuous intravenous infusion for 4 weeks (5 µg/m²/day for the first week and 15 µg/m²/day thereafter), followed by two treatment-free weeks (one cycle) for up to five cycles. The primary endpoint for the phase 2 part of the study was rate of complete remission (CR) within the first two cycles of treatment, including CR with incomplete hematologic recovery. Secondary endpoints included relapse-free survival (RFS), rate of advancement to alloHSCT, overall survival (OS), and incidence and severity of adverse events (AEs). Minimal residual disease (MRD) response (<10-4 leukemic cells by PCR or flow cytometry) was an exploratory endpoint. We present 39 pts who were treated at the phase 2 dose (5→15 µg/m²/day), including 18 pts from the dose expansion cohort of the phase 1 part and 21 pts from the phase 2 part of the study.Results: 39 pts received blinatumomab at a dose of 5→15 µg/m²/day. The median (range) age was 9 (2–16) years; 62% of pts were male. Sixteen (41%) pts had one and 16 (41%) pts had two or more prior salvage therapies, respectively; seven (18%) were either primary refractory or had refractory relapse. Twenty-five (64%) pts had received prior alloHSCT; of those, six (16%) had one relapse and 19 (50%) had two or more relapses. Of the 39 pts, 34 (87%) had relapsed within 6 months prior to study entry. The median (range) time from last prior relapse to the relapse at study entry was 2.1 (0–13.7) months. 69% of pts had bone marrow blast infiltration of ≥50%. 19 (49%) pts started and completed one cycle of blinatumomab treatment (two cycles, 4 [10%] pts; three cycles, 2 [5%] pts). During the first two treatment cycles, 12 pts achieved CR, (31%; 95% CI, 17%–48%), mainly during the first cycle. Two additional pts (5%) had blast-free hypoplastic or aplastic bone marrow. Among pts with CR in the first two cycles, five (42%) had complete MRD response. Median RFS for CR responders was 5.6 (95% CI, 2.6–12.1) months. Among all 39 pts, median OS was 4.3 (95% CI, 3.6–8.1) months with 6 months of study follow-up time. Six (50%) of the 12 pts with CR proceeded to alloHSCT. An additional five pts who did not respond to blinatumomab received alloHSCT after blinatumomab treatment was stopped. All pts experienced AEs, mostly flu-like symptoms consistent with the mechanism of action of blinatumomab. AEs regardless of causality occurring in >20% of pts were pyrexia (74%), anemia (33%), nausea (31%), headache (28%), hypertension (26%), increased alanine aminotransferase (23%), and cough (21%). The most common grade ≥3 AEs included anemia (26%), pyrexia (21%), increased alanine aminotransferase (18%), increased aspartate aminotransferase (18%), and febrile neutropenia (15%). Cytokine-release syndrome occurred in three (8%) pts, two of whom (5%) had grade 3 events.Conclusions: Blinatumomab showed promising antileukemia activity in heavily pretreated pediatric relapsed/refractory B-cell precursor ALL pts, with a median time from last relapse of 2.1 months. Half of the pts who responded within the first two cycles were able to receive alloHSCT following blinatumomab-induced remission, suggesting that blinatumomab may open a window for alloHSCT in those pts who are resistant to salvage chemotherapy. DisclosuresGore:Amgen Inc.: Travel Support Other. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities.. Zugmaier:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Hu:Amgen Inc.: Employment, Equity Ownership. Mergen:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Fischer:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. von Stackelberg:Amgen Inc.: Consultancy, Honoraria.

Outstanding Outcome for Children with Standard Risk-Low (SR-Low) Acute Lymphoblastic Leukemia (ALL) and No Benefit to Intensified Peg-Asparaginase (PEG-ASNase) Therapy: Results of Children’s Oncology Group (COG) Study AALL0331

▪Introduction: Overall, children with new-onset SR (age 1-9 years (yr), WBC <50,000/microliter) B-ALL enrolled on COG AALL0331 achieved excellent 5-yr event free (EFS) (89%) and overall survival (OS) (96%) (Maloney, ASH 2013). AALL0331 utilized a common 3-drug induction (IND), with post-IND assignment into refined risk groups per clinical, cytogenetic, and early response criteria. The SR-Low group was defined by favorable cytogenetics (triple trisomies of chromosomes 4+10+17 or ETV6-RUNX1), no central nervous system or testicular leukemia, and rapid marrow response (<5% blasts by day (d) 15 and end-IND minimal residual disease (MRD) <0.1%). Given an expected EFS >90%, the study sought to improve outcome in this group without adding significant toxicity. Published data had shown that hyperdiploid B-ALL blasts and those with the ETV6-RUNX1 fusion have enhanced in vitro ASNase sensitivity, and ASNase intensification had been effective and well tolerated in several pediatric trials. Thus, AALL0331 randomized SR-Low patients (pts) to standard post-IND therapy with or without 4 additional doses of PEG-ASNase given at 3-week intervals during consolidation (CON) and interim maintenance (IM). We now report the efficacy results for this group.Methods: AALL0331 enrolled 5377 SR-ALL pts from 4/2005-5/2010. All pts received standard IND (vincristine (VCR), dexamethasone (DEX), PEG-ASNase, intrathecal methotrexate (IT MTX)). At end-IND, 1857 pts meeting SR-Low criteria were randomized to one of two regimens, Low Risk Standard (LRS) or Low Risk ASNase (LRA), with identical CON (mercaptopurine (MP) 75 mg/M2 d1-28, VCR 1.5 mg/M2d1, IT MTX d1,8,15) and IM (DEX d1-5,29-33, MP d1-50, oral MTX weekly x8, IT MTX d29) phases except for additional PEG-ASNase (2500 IU/M2/dose) in LRA (CON d1,22 and IM d15,36). Subsequent delayed intensification (DI) and maintenance (MTC) phases were identical. After 6/2008, based on CCG-1991 SR-ALL efficacy analyses, the IM backbone was changed to escalating dose intravenous (IV) MTX (VCR d1,11,21,31,41, MTX d1,11,21,31,41, IT MTX d31) in both regimens (LRS-IV and LRA-IV).Results: The 5-yr continuous complete remission (CCR) and OS rates (SE) for SR-Low pts (n=1857) were 95.2% (0.6) and 98.8% (0.3). Consistent with the results of CCG-1991, the 3-yr EFS was numerically higher with IV MTX (99.0% (0.4) vs 97.0% (0.5), p=0.16) but the difference did not reach statistical significance. PEG-ASNase intensification did not significantly improve outcome, with 5-yr CCR rates for LRA/LRA-IV vs LRS/LRS-IV of 96.0% (0.8) vs 94.4% (1.0) (p=0.1), and 5-yr OS rates of 98.3% (0.6) vs 99.3% (0.4) (p=0.05). Comparing pts randomized pre/post the IV MTX amendment, no advantage to PEG-ASNase intensification was observed with either the oral (5-yr EFS: LRA 96.0% (0.8) vs LRS 93.8% (1.0), p=0.2) or the IV MTX based IM regimens (3-yr EFS: LRA-IV 99.0% (0.6) vs LRS-IV 99.0% (0.6), p=0.9). Using more current COG MRD definitions for low risk ALL (d8 peripheral blood MRD <1% and d29 marrow MRD <0.01%), the 5-yr EFS/OS for SR-Low patients were 96.4% and 98.8%. Treatment-related adverse events were uncommon but occurred more frequently with PEG intensification. As of 12/31/2013 there were 72 relapses, 13 deaths in remission, and 4 second malignancies.Conclusions: Data from AALL0331 show that, using sentinel genetic lesions and MRD response, about 35% of SR B-ALL patients meet LR criteria and are almost certain to be cured using a low intensity regimen comprised of a 3-drug IND and post-IND therapy without intensive consolidation or high dose MTX, an approach that limits the cumulative doses of anthracyclines (75 mg/m2) and alkylating agents (1000 mg/m2). DisclosuresBorowitz:Becton Dickinson Biosciences: Research Funding. Hunger:Sigma Tau Pharmaceuticals: Honoraria; Jazz Pharmaceuticals: Honoraria.

Ibrutinib Treatment of Relapsed CLL Following Allogeneic Transplantation: Sustained Disease Response and Promising Donor Immune Modulation

Background: Treatment of relapsed chronic lymphocytic leukemia (CLL) with ibrutinib results in high rates of progression-free and overall survival. Ibrutinib, an irreversible inhibitor of Bruton’s tyrosine kinase (BTK), is FDA-approved for use in relapsed CLL. Ibrutinib may also modulate donor T cell alloimmunity via inhibition of interleukin-2-inducible kinase (ITK). Here we report the effects of ibrutinib salvage therapy in 5 CLL patients who relapsed following allogeneic hematopoietic cell transplantation (allo-HCT). In addition to minimal residual disease (MRD) response measurements, we also assessed donor T cell chimerism and donor B cell immune reconstitution following ibrutinib therapy.Methods: Five patients with high-risk CLL relapsed 1-8.5 yrs following allo-HCT. Four patients had never achieved donor CD3 T cell chimerism >95% following reduced-intensity transplant. Ibrutinib 420mg daily was started 1 mo-2 yrs after clinical relapse. Four of the 5 patients remain on ibrutinib with treatment courses ranging from 3-17 mos. CLL MRD was measured by IgH high-throughput sequencing (HTS) using the ClonoSIGHTTM test (Sequenta, Inc.), which has the sensitivity to detect 1 CLL clone per million leukocytes. Lymph node (LN) size was assessed by CT scan and reported as the sum of the products of the LN diameters (SPD). Donor B cell reconstitution was determined by IgH HTS quantification of total IgH molecules and unique IgH clonotypes.Results: Lymphocytosis was observed in all 5 patients following initiation of ibrutinib treatment, consistent with previous reports. In 2 patients who received >1 yr of ibrutinib treatment, lymphocytosis peaked at 3 wks and 8 wks after initiation of treatment and slowly declined thereafter, fully resolving within 1 yr (Fig 1A). All 4 patients with pathologic lymphadenopathy prior to treatment experienced dramatic LN reduction (Fig 1B; 68% average reduction in LN size after 3 mos on ibrutinib). The longest duration of follow-up is reported for patient SPN 3975, who had a 17p deletion and received ibrutinib for 39 mos. Treatment was discontinued after CLL MRD became undetectable by ClonoSIGHT (Fig 1C). Evidence of donor T cell immune modulation included achievement of full donor CD3 chimerism after 1 yr and resolution of oral and skin chronic graft-versus-host disease (GVHD) after 6 mos. Although this patient has been off ibrutinib for >8 mos, full donor chimerism persists and CLL MRD remains undetectable (Fig 1C). Before ibrutinib treatment, donor B cells (excluding the patient’s CLL clone) accounted for <0.2% of total PBMC as determined by IgH HTS. Following discontinuation of ibrutinib, the percentage of donor B cells increased within 6 months, and now comprises >1% of PBMC (Fig 1D). Furthermore, recovering B cells have diverse, low frequency IgH clonotypes (Fig 1E). Together, our findings show rapid, sustained, and diverse immune reconstitution without CLL recurrence following ibrutinib discontinuation.Conclusions: Ibrutinib provides effective salvage therapy for CLL relapse following allo-HCT. Post-transplant CLL relapse is often extra-nodal and our experience shows ibrutinib is effective in clearing both nodal and extra-nodal disease. Here we present one patient who stopped therapy after achieving MRD negativity and maintains undetectable disease 8 mos following ibrutinib discontinuation. Ibrutinib treatment demonstrates promising donor immune modulation by promoting full donor chimerism and resolution of chronic GVHD. Our five patient experience supports using ibrutinib in relapsed CLL patients following allo-HCT. Clinical trials are needed to determine the best duration of ibrutinib therapy following post-allo-HCT relapse, chronic GVHD treatment efficacy, and the role of ibrutinib maintenance following allo-HCT. [Display omitted] DisclosuresKong:Sequenta, Inc.: Employment, Equity Ownership. Klinger:Sequenta, Inc.: Employment, Equity Ownership. Faham:Sequenta, Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees. Coutre:Pharmacyclics, Inc.: Consultancy, Research Funding. Miklos:Sequenta, Inc.: Research Funding.

Clinical Implication of BCR/ABL Fusion Transcript Monitoring in Addition to Ig/TCR Gene Rearrangement-Based Minimal Residual Disease in Philadelphia Chromosome-Positive Childhood Acute Lymphoblastic Leukemia

▪Background: Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) accounts for about 3% of pediatric ALL and has a poor prognosis. Advances of treatment due to the tyrosine kinase inhibitor imatinib have improved the cure rates. According to recent guidelines in the amended European intergroup trial on Ph+ ALL (EsPhALL), patients with rapid minimal residual disease (MRD) response and negativity during further treatment are no longer eligible for allogeneic stem cell transplantation (alloSCT). This down-grading of therapy in a circumscribed patient cohort with favorable prognosis is a desirable development as stem cell transplantation still implies a considerable risk of toxicity. These guidelines refer to MRD by immunoglobulin/T-cell receptor (Ig/TCR) gene rearrangements and do not consider monitoring of the BCR/ABL fusion transcript as long as informative results for Ig/TCR MRD are available. However, discrepancies between the results of the two methods occur. This complicates the decision on alloSCT indication if Ig/TCR MRD becomes negative while the BCR/ABL fusion transcript remains detectable.Objectives/Methods: We therefore evaluated the prognostic relevance of this specific combination of findings, i.e. the continuous negativity for Ig/TCR MRD and persistently positive results for BCR/ABL after the second intensive consolidation block or later, in 16 pediatric patients with Ph+ ALL. They were identified among 139 German and Austrian Ph+ patients treated in the ALL-BFM 2000 or EsPhALL trial from August 1, 1999 to July 31, 2013. Twelve out of the 16 patients received imatinib in first-line treatment intermittently as previously described in the EsPhALL protocol (Biondi A et al Lancet Oncol. 2012) or continuously as recommended by the amended EsPhALL protocol.Results: Eight of the 16 identified patients received an alloSCT in first complete remission (1st CR), whereas the remaining eight patients were treated with chemotherapy only. Of the eight patients with alloSCT, seven are in first continuous complete remission (1st CCR) with median EFS of 7.6 years, one patient died after second relapse. In the group of eight patients without alloSCT three are in 1st CCR with a median EFS of 2.6 years, four patients are in 2nd CR after relapse (3/4 had alloSCT in 2nd CR, median EFS 4.7 years), and one patient with Down syndrome died of an infectious complication. Remarkably, two patients of the latter group (both with M-BCR) showed a protracted increase of BCR/ABL copy numbers over several years with neither morphological signs of relapse nor Ig/TCR MRD based reappearance. One of them eventually suffered a relapse 5 years after diagnosis, one is still in 1st CCR with EFS of 5.2 years.Conclusion: The data suggest that patients with Ig/TCR MRD negativity and persistently detectable BCR/ABL fusion transcript have a high risk of relapse when treated with chemotherapy only and may benefit from alloSCT. However, patient numbers are currently too small to deduce recommendations from this observation. Further investigation of a larger cohort with longer follow-up is needed to confirm the prognostic importance of BCR/ABL fusion transcript monitoring in addition to Ig/TCR MRD, especially considering a potential additional impact of the recently implemented continuous imatinib treatment. One additional patient would have met the diagnostic inclusion criteria of this analysis. He had an extensive increase of BCR/ABL fusion transcript at the end of maintenance treatment while being in morphological remission and negative for Ig/TCR MRD. This patient proved to be BCR/ABL positive in granulocytes revealing a chronic myeloid leukemia (CML) misdiagnosed as ALL during initial blast crisis. This indicates that an underlying CML might be taken into consideration also in other patients of the analyzed cohort. In consequence, BCR/ABL in granulocytes is now tested in all newly diagnosed Ph+ ALL patients in Germany to ensure the differentiation of BCR/ABL positive ALL vs. CML in blast crisis. DisclosuresNo relevant conflicts of interest to declare.

Chemoimmunotherapy Combining Vincristine, Dexamethasone and Epratuzumab (hLL2) As Salvage Regimen for Older Relapsed/Refractory, CD22+ B-Acute Lymphoblastic Leukemia (B-ALL) Patients: Results of the French Non-Intensive Phase 2 Prospective Cheprall Study

▪Purpose: Best supportive care is generally offered to older patients presenting with refractory/relapsed acute lymphoblastic leukemia (ALL). There is clearly a need for new therapeutic approaches in these older patients for whom aggressive chemotherapies cannot be administered.Materials and Methods: The present study evaluated the addition of epratuzumab (hLL2), a humanized monoclonal therapeutic antibody against CD22, to the combination of vincristine and dexamethasone in older patients (>55 years) with relapsed/refractory CD22+ B-ALL. The salvage regimen consisted of epratuzumab 360 mg/m²/d iv days 1, 8, 15, and 22, vincristine 2 mg iv days 1, 8, 15 and 22, and dexamethasone 40 mg/d po days 1, 8, 15, and 22. Morphologic and phenotypic minimal residual disease (MRD) responses were determined between 4 and 6 weeks from day 1.Results: Between November 2010 and December 2013, 26 patients from six French centers were enrolled in the study. One case was excluded because of progression before receiving the treatment, while 2 younger patients were inappropriately included (49-year old female in fourth relapse and 32-year old female with refractory second relapse). Among the 25 patients considered for analyses, there were 13 males and the median age was 65 years. Eighteen, 4, 1, and 1 patients were in first, second, third, and fourth relapse, respectively, and one case had refractory B-ALL. Median percentage of blasts in bone marrow was 72%. Karyotypes were as follow: normal n=8; Ph+ n=6, complex n=1, MLL rearrangement n=1, hyperdiploidy n=2, hypodiploidy n=2, 17p duplication n=1, del9p n=1, t(1;19) n=1, t(13;14) n=1, 14 abnormality n=1. Median interval between diagnosis and salvage regimen was 16 months. Three patients were previously allotransplanted. Two patients died of progression during treatment. Salvage regimen was overall well tolerated, since the large majority of grade 3/4 toxicities were expected pancytopenia. One grade 3 toxicity was related to the first epratuzumab infusion, but the patient received the three other infusions without events. One grade 3 renal injury and one grade 4 hypertriglyceridemia of unclear etiology also were documented.The overall response rate was 40% (n=10), including 4 complete responses (CR) and 1 CR with incomplete platelet recovery (CRp) (20%), and 5 partial responses (PR) (20%). Two patients in CR/CRp were documented with negative MRD. All patients in CR/CRp and 1 patient in PR received a second cycle as consolidation. All patients died of disease progression, except two non-responder cases. Median OS was 4 months (range: 0.5-43). Median DFS for those achieving CR/CRp was 4 months (range: 1-8).Conclusion: Non-intensive chemoimmunotherapy combining vincristine/dexamethasone/epratuzumab provides encouraging results in this very high-risk, refractory/relapsed, older population. These results pave the way for integrating epratuzumab within first-line chemotherapies in older CD22+ B-ALL patients. This trial is registered at http://clinicaltrials.gov/ct no.NCT01219816. DisclosuresLeguay:Gilead Sciences: Research Funding. Goldenberg:immunomedics: Employment. Wegener:immunomedics: Employment.

Invasive Candida Infections in Pediatric Patients Treated on the Pilot Study of Decitabine and Vorinostat with Chemotherapy for Relapsed ALL: A Report from the Therapeutic Advances in Childhood Leukemia & Lymphoma (TACL) Consortium

▪Introduction Children and young adults with relapsed acute lymphoblastic leukemia (ALL) are at high risk for infectious complications, particularly invasive fungal infections, during their intensive re-induction therapy. We report results of a Pilot study investigating decitabine and vorinostat in combination with intensive re-induction chemotherapy for children and young adults with relapsed or refractory ALL. This study is currently open through the TACL Consortium [NCT01483690] and all patients and/or their parents or guardians signed informed consent to participate in this institutional review board approved therapeutic trial in accordance to the Declaration of Helsinki.Methods Patients 1-25 years of age with 2nd or greater relapse or refractory ALL are eligible. Seventeen patients have enrolled with a median age of 12 years (range, 19 months - 21 years). Patients received one course of therapy which included decitabine (15mg/m2 days 1-7; 15-21), vorinostat (180mg/m2 days 3-10; 17-24), vincristine (1.5mg/m2 days 10, 17, 24, 31), dexamethasone (10mg/m2/dose BID days 8-12; 22-26), mitoxantrone (10mg/m2 days 8, 9), PEG-asparaginase (2500 IU/m2 days 10, 24) and intrathecal methotrexate (dosed according to age and CNS status). Nine patients (53%) relapsed after a prior allogeneic hematopoietic cell transplant and 5 patients had refractory disease (29%) prior to enrolling on this study. Initial infection prophylaxis guidelines did not require anti-bacterial or anti-fungal therapy.Results The study was suspended after 5 patients enrolled due to 2 patients reporting a DLT [Grade 3 cholestasis/steatosis, Grade 4 bilirubin (n=1); Grade 3 delirium, Grade 4 seizure, Grade 4 somnolence (n=1)] and 4 of the 5 patients (80%) reporting non-albicans Candidemia [C. kruseii (n=2), C. lusitaniae (n=1), C. guillermondii (n=1)]. Based on this significant rate of fungal infection, despite all patients receiving prophylactic anti-fungal therapy (micafungin n=2, fluconazole n=1, amphotericin n=1), the study was amended to decrease the decitabine dose (15mg/m2 to 10mg/m2) and duration of decitabine (days 1-7; 15-21 to 1-5; 15-19) as well as require treatment dose non-azole class anti-fungal therapy (echinocandin or amphotericin) to be given to all patients on study. Twelve patients enrolled post-amendment; only 1 of 12 (8.3%) experienced a fungal infection (C. guillermondii). Of note, this infection occurred in a patient using fluconazole for prophylaxis in place of a protocol-specified agent. There have been no fungal infections reported to date for the 11 patients on study who have received echinocandin or amphotericin therapy at treatment doses. Treatment responses include 9 patients achieving a complete remission (CR) (53%), 5 with stable disease (29%), two treatment related deaths and 1 patient removed from protocol therapy on day 6 based on the physician’s decision. The median minimal residual disease (MRD) response in patients who achieved a CR and submitted bone marrow samples for end of therapy testing (n=5) was 0.056% (range, 0.00%-5%).Conclusions We report a substantial initial incidence of invasive Candida infections in patients treated with decitabine and vorinostat in combination with intensive chemotherapy despite anti-fungal prophylaxis which appears to be abrogated once the fungal prophylaxis was required at treatment doses using either an echinocandin or amphotericin class agent. As well, the lower dose and duration of decitabine may have contributed to this improvement, resulting in potentially shorter periods of neutropenia which may contribute to the risk of fungal disease. The mechanism for the unique propensity for non-albicans Candida infections in this study remains unclear. The initial response to this regimen incorporating epigenetic therapy is promising with correlative biology studies investigating methylation, acetylation and gene expression changes pending study completion. The study continues to accrue at a dose expansion cohort. DisclosuresOff Label Use: Decitabine in relapse ALL Vorinostat in relapse ALL.

Transfer of Ex Vivo Expanded NK and γδT Cells from Untouched Posttransplant PBMCs to Clear Minimal Residual Disease in Acute Myeloid Leukemia

GMP-grade NK cell expansion for clinical purpose has been demonstrated feasible and safe. Here we share our pilot data on posttransplant immunotherapy with ex vivo expanded NK cells to treat minimal residual disease in a pediatric patient with posttransplant relapsed myeloid leukemia. Our patient, a 13 year old boy who underwent 2nd allogeneic stem cell transplantation (haploidentical stem cell transplantation from his mother) due to posttransplant relapsed acute myeloid leukemia. After the 2nd haploidentical stem cell transplantation (SCT) minimal residual disease (MRD) was detected by multiparameter flow cytometry and by two molecular markers CALM-AF10 fusion transcript and a NRAS-mutation. For posttransplant compassionate use immunotherapy by NK cell transfer, NK cells were expanded from untouched isolated PBMCs of the patient post 2nd haploidentical SCT. GMP-grade expansion of the NK cells was done under static conditions in our GMP-facility. Isolated PBMCs were pooled with 100Gy irradiated K562mb15 4-1BBL feeder cells (kindly provided by Dario Campana) in a proportion of 1:20 (NK to K562mb15 4-1BBL). PBMCs and K562mb15 4-1BBL were seeded in conventional cell culture flasks (175cm2) at a density of 1.1E6 cells/ml. Cell culture media contained RPMI1640 supplemented with 10% AB-human serum, 1% L-glutamine and 100IU Proleukine® IL2/ml. Cell culture was monitored daily for cell number, white blood cell differentiation, pH of the cell culture, glucose metabolism, lactate production and microbial sterility testing at the beginning and the end of the expansion period. The cell product was harvested on day 15-17. Fresh isolated PBMCs and the expanded NK cell product were characterized by flow cytometry. NK cells were expanded >1000 fold (3.1 and 3.4 log-fold) in 14-17 days. The product contained a total number of 9.8E9 and 19.9E9 cells, which was 328 and 665E6/kgBW. The expansion protocol supports NK and γδ T cell expansion whereas the number of αβ T cells stays stable. Cytotoxicity assay against various targets revealed excellent cellular cytotoxicity and antibody dependent cellular cytotoxicity. To prevent relapse in our patient with posttransplant MRD positivity, NK cells from the patient post 2nd haploidentical SCT were expanded for cellular immunotherapy. 2 weeks post 1st NK cell transfer (day +170) the patient achieved complete MRD response in the bone marrow. Unfortunately the patient showed detectable MRD one month later. Therefore another NK cell expansion and transfer was done. 2 weeks post 2nd NK cell transfer (day +232) the patient again achieved complete MRD response in the bone marrow and is in complete molecular remission ever since (day +340). The NK cell products were tolerated well. Transient coughing and temporary increase of temperature were registered. Both, in vitro and in vivo effect of the NK cell product were documented. Clinical use of expanded and activated NK cells and γδ T cells can induce molecular remission in posttransplant MRD positive acute myeloid leukemia. DisclosuresNo relevant conflicts of interest to declare.

MRD Eradication Should be the Therapeutic Goal in Mantle Cell Lymphoma and May Enable Tailored Treatment Approaches: Results of the Intergroup Trials of the European MCL Network

Background: Minimal residual disease (MRD) measurement is an increasingly recognized tool for response assessment in B-cell malignancies and represents a useful surrogate marker for prognosis, allowing prediction of the clinical course prior to clinical study endpoints. Based on the randomized intergroup trials of the European MCL Network for patients with stage II-IV mantle cell lymphoma (MCL) investigating immuno-chemotherapy followed by autologous stem cell transplantation (ASCT) for patients <65 yrs and rituximab or interferon maintenance for patients > 65 yrs, we prospectively monitored MRD.Methods: According to the protocols MRD analyses were performed after completed induction and subsequently in 3-monthly intervals after ASCT or 2-monthly during maintenance until progression. MRD results were evaluated according to ESG criteria (van der Velden, Leukemia 2007) and compared with clinical outcome. RQ-PCR was designed to reach a sensitivity of 10E-5, MRD negativity was defined as a negative RQ-PCR result with a sensitivity of at least 10E-4. Patients in complete or partial remission 6 months after ASCT/end of induction (MCL Younger/MCL Elderly) were included in this analysis. During follow-up MRD status in peripheral blood (PB) was assessed and defined as negative, if there were only negative MRD values, or positive in case of at least one positive MRD value during a 6-months period. Landmark analyses were performed for progression-free survival (PFS) according to MRD status for each 6-months period until 4 years of follow-up and PFS was compared between PB positive and PB negative patients.Results: Among patients in remission 6 months after ASCT/end of induction, MRD results during follow-up were available in 406 patients (255 MCL Younger,151 MCL Elderly). The distribution into low, intermediate, and high risk MIPI of 44%, 34% and 22%, respectively, was similar to the total study population. During follow-up period, percentage of patients with evaluable MRD status dropped from about 50%-55% during the first two years to 40%-45% during years 3-4, and less than 40% afterwards. The rate of MRD positive samples was about 20-25% during the first 3 years, and less than 20% in the subsequent follow-up.In each landmark analysis, a positive MRD status in PB was highly associated with a shorter PFS. This association was independent of baseline MIPI score, treatment arm or protocol (Figure 1). Thus, the prognostic value of MRD positivity was maintained in both trials MCL Younger and MCL Elderly. Remarkably, landmark analyses at all time points indicated a strong association also of low-level MRD with a shortened PFS. Finally, MRD analyses in 76 patients at relapse confirmed the close association of clinical relapse to MRD positivity, with only 10 patients (13%) being PB-negative.Conclusion: Our data demonstrate that achievement and preservation of MRD negativity is the strongest independent predictor of prognosis in patients with MCL. Applying MRD status as tool for tailored treatment, therapeutic approaches should focus on a maximum MRD response to improve long term outcome. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Prognostic Impact of Minimal Residual Disease in Adult Acute Lymphoblastic Leukemia

SUMMARY While adult acute lymphoblastic leukemia (ALL) is curable in 40–50% of the patients, the individual prognosis is rather unpredictable due to associated biological and clinical risk factors. In both B- and T-precursor ALL, minimal residual disease (MRD) represents the most sensitive prognostic marker, useful to support critical treatment decisions, ranging from allogeneic stem cell transplantation in patients with inadequate MRD response to chemotherapy only in MRD responsive ones. This optimized risk-adapted strategy allows to spare transplant-associated morbidity and mortality in patients curable by chemotherapy. Further progress is expected from the integration of the MRD-based strategy with improved pediatric-type regimens and novel targeting agents for discrete ALL subsets. These changes are increasing the cure rate to above 50%.

Long-term results of the GIMEMA VEL-03-096 trial in MM patients receiving VTD consolidation after ASCT: MRD kinetics' impact on survival

Polymerase chain reaction (PCR)-based minimal residual disease (MRD) analysis is a useful prognostic tool in multiple myeloma (MM), although its long-term impact still needs to be addressed. This report presents the updated results of the GIMEMA-VEL-03-096 trial. Thirty-nine MM patients receiving bortezomib-thalidomide-dexamethasone after autologous transplantation were monitored for MRD by both nested and real-time quantitative-PCR until relapse. Our data confirm the strong impact of MRD on survival: overall survival was 72% at 8 years median follow-up for patients in major MRD response versus 48% for those experiencing MRD persistence (P=0.041). In addition, MRD kinetics resulted predictive for relapse: indeed median remission duration was not reached for patients in major MRD response, 38 months for those experiencing MRD reappearance and 9 months for patients with MRD persistence (P<0.001). Moreover: (1) 26 patients achieving major MRD response (67%) benefit of excellent disease control (median TNT: 42 months); (2) MRD reappearance heralds relapse, with a TNT comparable to that of MRD persistence (9 versus 10 months, P=0.706); (3) the median lag between MRD reappearance and need for salvage treatment is 9 months. These results suggest the usefulness of a long-term MRD monitoring in MM patients and the need for maintenance or pre-emptive treatments ensuring durable responses.

Augmented post-remission therapy for a minimal residual disease-defined high-risk subgroup of children and young people with clinical standard-risk and intermediate-risk acute lymphoblastic leukaemia (UKALL 2003): a randomised controlled trial

No randomised study has shown whether stratification of treatment by minimal residual disease (MRD) response improves outcome in children and young people with acute lymphoblastic leukaemia (ALL). We assessed whether children and young people with clinical standard and intermediate-risk ALL who have persistent MRD at the end of induction therapy benefit from augmented post-remission therapy. Between Oct 1, 2003, and June 30, 2011, we enrolled eligible patients aged 1-24 years and initially categorised them into clinical standard-risk, intermediate-risk, and high-risk groups on the basis of a combination of National Cancer Institute criteria, cytogenetics, and early morphological response to induction therapy. Clinical standard-risk and intermediate-risk patients with MRD of 0·01% or higher at day 29 of induction (MRD high risk) were randomly assigned (1:1) to standard therapy (treatment regimens A and B) or augmented post-remission therapy (regimen C). Compared with standard therapy, the augmented treatment regimen (regimen C) included an additional eight doses of pegylated asparaginase, 18 doses of vincristine, and escalated-dose intravenous methotrexate without folinic acid rescue during interim maintenance courses. Computer randomisation was used for treatment allocation and was balanced for sex, age (<10 years vs ≥10 years), and white blood cell count at diagnosis (<50 × 10(9)/L vs ≥50 × 10(9)/L) by minimisation. Patients, clinicians, and data analysts were not masked to treatment allocation. The primary outcomes were event-free survival and overall survival. Analyses were by intention to treat. This trial is registered with Current Controlled Trials, number ISRCTN07355119. 533 MRD high-risk patients were randomly assigned to receive standard (n=266) or augmented (n=267) post-remission therapy. After a median follow-up of 70 months (IQR 52-91), 5-year event-free survival was better in the augmented treatment group (89·6% [95% CI 85·9-93·3]) than in the standard group (82·8% [78·1-87·5]; odds ratio [OR] 0·61 [95% CI 0·39-0·98], p=0·04). Overall survival at 5 years was numerically, but not significantly, higher in the augmented treatment group (92·9% [95% CI 89·8-96·0]) than in the standard therapy group (88·9% [85·0-92·8]; OR 0·67 [95% CI 0·38-1·17], p=0·16). More adverse events occurred in the augmented treatment group than in the standard group (asparaginase-related hypersensitivity in 18 [6·7%] in the augmented group vs two [0·8%] in the standard group and asparaginase-related pancreatitis in eight [3·0%] vs one [0·4%]; intravenous methotrexate-related mucositis in 11 [4·1%] vs three [1·1%] and methotrexate-related stomatitis in 48 [18·0%] vs 12 [4·5%]). Our findings suggest that children and young people with acute lymphoblastic leukaemia and 0·01% or more MRD at the end of remission induction therapy could benefit from augmented post-remission therapy. However, the asparaginase and intravenous methotrexate used in the augmented treatment regimen is associated with more adverse events than is the standard post-remission treatment regimen. Medical Research Council and Leukaemia and Lymphoma Research.

Key role for myeloid cells: Phase II results of anti‐GD2 antibody 3F8 plus granulocyte‐macrophage colony‐stimulating factor for chemoresistant osteomedullary neuroblastoma

Anti-G(D2) murine antibody 3F8 plus subcutaneously (sc) administered granulocyte-macrophage colony-stimulating factor (GM-CSF) was used against primary refractory neuroblastoma in metastatic osteomedullary sites. Large study size and long follow-up allowed assessment of prognostic factors in a multivariate analysis not reported with other anti-G(D2) antibodies. In a phase II trial, 79 patients without prior progressive disease were treated for persistent osteomedullary neuroblastoma documented by histology and/or metaiodobenzyl-guanidine (MIBG) scan. In the absence of human antimouse antibody, 3F8 + scGM-CSF cycles were repeated up to 24 months. Minimal residual disease (MRD) in bone marrow was measured by quantitative reverse transcription-polymerase chain reaction pre-enrollment and post-cycle #2, before initiation of 13-cis-retinoic acid. Study endpoints were: (i) progression-free survival (PFS) compared with the predecessor trial of 3F8 plus intravenously administered (iv) GM-CSF (26 patients) and (ii) impact of MRD on PFS. Using all 105 patients from the two consecutive 3F8 + GM-CSF trials, prognostic factors were analyzed by multivariate Cox regression model. Complete response rates to 3F8 + scGM-CSF were 87% by histology and 38% by MIBG. Five-year PFS was 24 ± 6%, which was significantly superior to 11 ± 7% with 3F8 + ivGM-CSF (p = 0.002). In the multivariate analysis, significantly better PFS was associated with R/R or H/R FCGR2A polymorphism, sc route of GM-CSF and early MRD response. MYCN amplification was not prognostic. Complement consumption was similar with either route of GM-CSF. Toxicities were manageable, allowing outpatient treatment. 3F8 + scGM-CSF is highly active against chemoresistant osteomedullary neuroblastoma. MRD response may be an indicator of tumor sensitivity to anti-G(D2) immunotherapy. Correlative studies highlight the antineoplastic potency of myeloid effectors.

Current approach to relapsed acute lymphoblastic leukemia in children

Recurrent acute lymphoblastic leukaemia(ALL) is a common disease for pediatric oncologists and accounts for more deaths from cancer in children than any other malignancy. Although most patients achieve a second remission, about 50% of relapsed ALL patients do not respond to salvage therapy or suffer a second relapse and most children with relapse die. Treatment must be tailored after relapse of ALL, since outcome will be influenced by well-established prognostic features, including the timing and site of disease recurrence, the disease immunophenotype, and early response to retrieval therapy in terms of minimal residual disease(MRD). After reinduction chemotherapy, high risk(HR) patients are clear candidates for allogeneic stem cell transplantation(SCT) while standard risk patients do better with conventional chemotherapy and local therapy. Early MRD response assessment is currently applied to identify those patients within the more heterogeneous intermediate risk group who should undergo SCT as consolidation therapy. Recent evidence suggests distinct biological mechanisms for early vs late relapse and the recognition of the involvement of certain treatment resistance related genes as well cell cycle regulation and B-cell development genes at relapse, all providing the opportunity to search for novel target therapies.

Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) In Adults With Philadelphia Chromosome (Ph)-Negative Acute Lymphoblastic Leukemia (ALL): Results From The Group For Research On Adult ALL (GRAALL)

▪ PurposeThe pediatric-inspired intensified GRAALL protocol yielded a marked improvement in the outcome of adults with Ph-negative acute lymphoblastic leukemia (ALL) (Huguet et al,JCO 2009), raising the issue of the place of allogeneic HSCT in this new context. We report here the results associated with HSCT in first complete remission (CR) in younger adults treated in the GRAALL-2003/2005 trials. Patients and methodsIn these trials, HSCT was offered in first CR to patients aged 15-55 years with ALL at higher risk of relapse. High-risk factors included white blood count >30 x 109/L for B-lineage ALL, central nervous system (CNS) involvement, t(4;11)/MLL anomalies, t(1;19), low hypodiploidy/near triploidy, complex karyotype, early resistance to the steroid prephase (CsR), early resistance to chemotherapy (ChR) as assessed by poor bone marrow blast clearance at day 8, and late CR. Per protocol, HSC donor should be a matched sibling or an unrelated donor (10/10 or eventually 9/10 HLA matched) and conditioning regimen should include single fraction 10-Gy or fractionated 12-Gy total body irradiation (TBI) and high-dose cyclophosphamide. The role of HSCT was evaluated by HSCT versus no-HSCT cohort comparison (Mantel-Byar time-dependent analysis). ResultsAmong the 522 high-risk patients eligible, 283 (54%) actually received HSCT in first CR (185 B-lineage and 98 T-lineage ALL; median age, 31 years). There were no significant differences in baseline characteristics and early response between HSCT and no-HSCT cohorts, except more HSCT patients with t(4;11)/MLL anomalies. Among the 283 HSCT patients, 46 had t(4;11)/MLL anomalies, 13 had CNS disease, 116 had CsR and 176 had ChR ALL. Origin of HSC was 140 sibling and 143 unrelated donors, including 47 unrelated donors with 1 HLA mismatch. The following HSCT protocol violations were observed: a) conditioning did not include TBI in 17 patients; b) 10 patients received reduced-intensity conditioning (RIC); and c) 13 patients received cord blood HSCT. These patients remained in the HSCT cohort for the analysis. With a median post-transplant follow-up of 3.5 years, post-HSCT cumulative incidence of relapse (CIR), non-relapse mortality (NRM) and relapse-free survival (RFS) were estimated respectively at 19% (95% CI, 15-25), 16% (95% CI, 12-21) and 64% (95% CI, 58-70) at 3 years, without any RFS difference between sibling and unrelated donors. A marked trend for a higher NRM was observed in patients aged 45 years or more (26% versus 13% at 3 years; HR, 1.6; p=0.059), while post-transplant CIR was similar in older and younger patients. Mantel-Byar RFS estimations showed no significant difference between both HSCT and no-HSCT cohorts (HR, 0.80; p=0.13), meaning that the risk factors used in these protocols failed to identify patients who could significantly benefit from HSCT in first CR. As minimal residual disease (MRD) had a major prognostic impact, we retrospectively analyzed the effect of HSCT in the 278/522 patients evaluated for 6-week Ig/TCR MRD level (154 HSCT and 124 no-HSCT patients, including 92 and 62 patients with MRD >=10-4, respectively). Mantel-Byar RFS estimations showed that HSCT did not benefit to patients with MRD <10-4 (HR, 1.2; p=0.67) as opposed to those with MRD >=10-4 (HR, 0.6; p=0.02), with a positive HSCT-by-MRD interaction (p=0.04) (Figure 1). [Display omitted] ConclusionIn adult patients with high-risk ALL in first CR treated in the GRAALL-2003/2005 trials, myeloablative allogeneic HSCT from sibling and unrelated donors was associated with a 64% RFS at 3 years. The 26% NRM observed at 3 years in patients aged 45 years or more suggests considering RIC-HSCT in these patients. MRD response appears to be a powerful tool to select patients who might benefit from HSCT. This selection tool will be prospectively evaluated in the next GRAALL-2013 trial.ND and AH contributed equally to the work. Disclosures:No relevant conflicts of interest to declare.

Philadelphia-Like Signature In Childhood Acute Lymphoblastic Leukemia: The AIEOP Experience

▪ BackgroundDespite the current risk-based stratification and therapies, up to 20% of pediatric patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) experience relapse. A major research effort is dedicated to identifying poor prognostic subgroups in the larger subset of patients with intermediate-risk disease, where most relapses occur. Recently, two groups in the US and the Netherlands independently identified a novel BCP-ALL subtype negative for the BCR/ABL fusion gene but with a gene-expression profile similar to Philadelphia chromosome-positive (Ph+) ALL. This ‘Ph-like' (or ‘BCR/ABL-like') subtype encompasses 10-15% of BCP-ALL patients, predicts high incidence of relapses and defines a candidate subgroup for targeted treatment with tyrosine kinase inhibitors and alternative drugs. AimAim of this project was to identify BCP-ALL Ph-like cases and their prognosis in patients treated in Study Protocols of the Italian Association of Pediatric Hematology and Oncology (AIEOP) MethodsIn the context of the Microarray Innovations in LEukemia (MILE) study, gene expression profiling was successfully performed on 400 Italian childhood BCP-ALL cases enrolled in AIEOP-BFM ALL2000/R2006 protocols, from whom material was available. The MILE classifier recognized the most common genetic subgroups, namely t(4;11), t(12;21), t(1;19) or t(9;22) positive, or high hyperdiploid (DNA index≥1.16). Out of 400 BCP-ALL cases, 143 negative for common fusion transcripts, non-high hyperdiploid (DNA index<1.16) and non-Down Syndrome, were defined as ‘B-others'. ResultsUsing signatures of known ALL subgroups, the likelihood to be close to one of the ‘known' classes was defined for each of the B-others samples. Specifically, 43 B-other cases (43/143=30.1%, about 10% of total BCP-ALL cohort) presented as a cluster with a gene expression signature close to the BCR/ABL signature, therefore referred to as ‘Ph-like'. Among B-others, Ph-like cases had a significantly increased proportion of males, age>10 years and WBC>20x109/L. The 5y event-free survival (EFS) of Ph-like patients was 54.8% (SE 8.2) vs 83.1% (3.9) in the remaining B-others patients (p<0.001), mostly due to an increased cumulative incidence of relapse (CIR: 33.9% (7.4) vs 14.9% (3.7); p=0.009). Notably, Ph-like patients did not differ for prednisone (PDN) and minimal residual disease (MRD) response or final risk stratification. Indeed, out of 36/43 stratified by MRD, only 7 patients had high-risk MRD, while 20 were MRD intermediate and 9 even MRD standard risk. Only 3 non-HR cases by MRD were then classified as HR based on PDN response. Of relevance, the significant difference in 5y EFS was confirmed in the 33 Ph-like patients with no HR features (59.8% (9.2) vs 88.5% (3.9) in the remaining B-others patients with similar features (p<0.001), with a significantly increased CIR (32.1% (8.4) vs 10.2% (3.7); p=0.005). Among 43 Ph-like cases, 1 was resistant and 1 died during the induction phase. Out of the 14 relapses, 10 were isolated medullary, and 4 combined with an extramedullary site (no CNS relapses). Two patients died in remission and no secondary malignancies occurred during the observation period. Overall, 25/43 (58.1%) Ph-like patients are alive in complete remission versus 84/100 (84.0%) in B-others, non Ph-like patients. Conclusions and perspectivesWe identified a ‘Ph-like' subgroup in the Italian cohort of children with BCP-ALL, associated to a poor outcome. Ph-like patients, independently of the other known risk features, could be considered eligible for alternative treatments. The genetic characterization of this subgroup is ongoing within the AIEOP-BFM research trial cooperative group, which is aimed at further defining the pathogenetic mechanisms and identifying the therapeutic translation. Disclosures:No relevant conflicts of interest to declare.

Trajectory of intensive treat-to-target disease modifying drug regimen in an observational study of an early rheumatoid arthritis cohort

ObjectivesStudies of early rheumatoid arthritis (RA) cohorts have analysed treatment response and prognostic factors at fixed time points. However, in treat-to-target protocols, therapeutic decision-making is dynamic and responsive to disease...

Use of Allogeneic Hematopoietic Stem-Cell Transplantation Based on Minimal Residual Disease Response Improves Outcomes for Children With Relapsed Acute Lymphoblastic Leukemia in the Intermediate-Risk Group

In children with intermediate risk of relapse of acute lymphoblastic leukemia (ALL), it is essential to identify patients in need of treatment intensification. We hypothesized that the prognosis of patients with unsatisfactory reduction of minimal residual disease (MRD) can be improved by allogeneic hematopoietic stem-cell transplantation (HSCT). In the Acute Lymphoblastic Leukemia-Relapse Study of the Berlin-Frankfurt-Münster Group (ALL-REZ BFM) 2002, patients with an MRD level of ≥ 10(-3) (n = 99) at the end of induction therapy were allocated to HSCT, whereas those with an MRD level less than 10(-3) (n = 109) continued to receive chemotherapy. MRD was quantified by real-time polymerase chain reaction for clone-specific T-cell receptor/immunoglobulin gene rearrangements. The probability of event-free survival for patients with MRD ≥ 10(-3) was 64% ± 5% in ALL-REZ BFM 2002 compared with 18% ± 7% in the predecessor study ALL-REZ BFM P95/96 (P < .001). This was mainly achieved by reducing the cumulative incidence of subsequent relapse (CIR) at 8 years from 59% ± 9% to 27% ± 5% (P < .001). The favorable prognosis of patients with MRD less than 10(-3) could be confirmed in those with a late combined or isolated bone marrow B-cell precursor (BCP) -ALL relapse (CIR, 20% ± 5%), whereas patients with an early combined BCP-ALL relapse had an unfavorable outcome (CIR, 63% ± 13%; P < .001). Allogeneic HSCT markedly improved the prognosis of patients with intermediate risk of relapse of ALL and unsatisfactory MRD response. As a result, outcomes in this group approximated those of patients with favorable MRD response. Patients with early combined relapse require treatment intensification even in case of favorable MRD response, demonstrating the prognostic impact of time to relapse.

Risk group assignment differs for children and adults 1–45 yr with acute lymphoblastic leukemia treated by the NOPHO ALL‐2008 protocol

The prognosis of acute lymphoblastic leukemia is poorer in adults than in children. Studies have indicated that young adults benefit from pediatric treatment, although no upper age limit has been defined. We analyzed 749 patients aged 1-45 yr treated by the NOPHO ALL-2008 protocol. Minimal residual disease (MRD) on days 29 and 79, immunophenotype, white blood cell count (WBC), and cytogenetics were used to stratify patients to standard-, intermediate-, or high-risk treatment with or without hematopoietic stem cell transplantation. Adults aged 18-45 had significantly lower WBCs at diagnosis compared with children aged 1-9 and 10-17 yr, but significantly more adults were stratified to high-risk chemotherapy (8%, 14%, 17%; P < 0.0001) or high-risk chemotherapy with transplantation (4%, 13%, 19%; P < 0.0001). This age-dependent skewing of risk grouping reflected more T-ALL (11%, 27%, 33%, P < 0.0001), poorer MRD response day 29 (MRD < 0.1%: 75%, 61%, 52%; P < 0.0001), and more MLL gene rearrangements (3%, 3%, 10%; P = 0.005) in older patients. Even if identical diagnostics, treatment, and risk stratification are implemented, more adults will be stratified to high-risk therapy, which should be considered when comparing pediatric and adult outcomes.

Retrospective monitoring of minimal residual disease using hairpin-shaped clone specific primers in B-cell lymphoma affected dogs

Lymphoma is one of the most common forms of cancer in dogs as it is in humans but, unlike humans, the cure rates in canines are still very low. Despite the fact that high grade B-cell lymphomas are considered to be chemotherapy responsive, almost all treated dogs ultimately relapse and die due to the residual malignant lymphocytes, namely minimal residual disease (MRD). It would be extremely valuable for clinicians to detect, monitor and quantify MRD for risk group stratification, effective treatment intervention and outcome prediction. The PCRs targeting the Ig gene rearrangements constitute one of the most reliable tools to this end. We have recently validated a method which exploits hairpin-shaped primers for quantifying MRD. In the present study, that method is conveniently used for retrospectively monitoring MRD in the peripheral blood of 8 dogs diagnosed with B-cell lymphoma who underwent chemotherapy. All dogs attained complete remission. The median disease-free interval was 254.5 days (range 63–774) while the median survival time was 313.5 days (range 143–817 days). At admission, all dogs, except one which had already been treated with prednisone, had circulating neoplastic cells. All dogs attained complete remission (CR) which was almost always matched with a complete MRD response. The persistence of MRD despite apparent CR indicated a worse prognosis and a short duration of CR. Finally, the relapse is consistently anticipated by the reappearance of MRD in the peripheral blood. The study confirmed the suitability of an MRD monitoring assay as a clinical decision-making tool.

Long-term follow-up of hematologic relapse-free survival in a phase 2 study of blinatumomab in patients with MRD in B-lineage ALL

AbstractPersistence or recurrence of minimal residual disease (MRD) after chemotherapy results in clinical relapse in patients with acute lymphoblastic leukemia (ALL). In a phase 2 trial of B-lineage ALL patients with persistent or relapsed MRD, a T cell–engaging bispecific Ab construct induced an 80% MRD response rate. In the present study, we show that after a median follow-up of 33 months, the hematologic relapse-free survival of the entire evaluable study cohort of 20 patients was 61% (Kaplan-Meier estimate). The hema-tologic relapse-free survival rate of a subgroup of 9 patients who received allogeneic hematopoietic stem cell transplantation after blinatumomab treatment was 65% (Kaplan-Meier estimate). Of the subgroup of 6 Philadelphia chromosome–negative MRD responders with no further therapy after blinatumomab, 4 are in ongoing hematologic and molecular remission. We conclude that blinatumomab can induce long-lasting complete remission in B-lineage ALL patients with persistent or recurrent MRD. The original study and this follow-up study are registered at www.clinicaltrials.gov as NCT00198991 and NCT00198978, respectively.