Peterson, Mary

X-linked reticulate pigmentary disorder (XLPDR, Mendelian Inheritance in Man #301220) is a rare syndrome characterized by recurrent infections and sterile multiorgan inflammation. The syndrome is caused by an intronic mutation in POLA1, the gene encoding the catalytic subunit of DNA polymerase-α (Pol-α), which is responsible for Okazaki fragment synthesis during DNA replication. Reduced POLA1 expression in this condition triggers spontaneous type I interferon expression, which can be linked to the autoinflammatory manifestations of the disease. However, the history of recurrent infections in this syndrome is as yet unexplained. Here we report that patients with XLPDR have reduced NK cell cytotoxic activity and decreased numbers of NK cells, particularly differentiated, stage V, cells (CD3 – CD56 dim ). This phenotype is reminiscent of hypomorphic mutations in MCM4 , which encodes a component of the minichromosome maintenance (MCM) helicase complex that is functionally linked to Pol-α during the DNA replication process. We find that POLA1 deficiency leads to MCM4 depletion and that both can impair NK cell natural cytotoxicity and show that this is due to a defect in lytic granule polarization. Altogether, our study provides mechanistic connections between Pol-α and the MCM complex and demonstrates their relevance in NK cell function.

Abstract Abstract 1749 BACKGROUND: We have previously reported that transformation of a myeloproliferative neoplasm (MPN) to acute leukemia or blast phase (MPN-BP) is accompanied by a median survival of 2.6 months (range 0–24.2 months) (Mesa et. al. Blood 2005) despite treatment. Allogeneic stem cell transplantation (ASCT) offers a potential for cure. We reviewed 13 patients with MPN – BP who were candidates for ASCT, and 8 of those patients received ASCT after induction chemotherapy. METHODS: Retrospective analysis of individuals who had a clear antecedent myeloproliferative neoplasm (essential thrombocythemia (ET), polycythemia vera (PV), or myelofibrosis (MF) (either primary (PMF) or post ET/PV)), transformed to MPN-BP, and were candidates for ASCT. Clinical characteristics at each phase of illness, therapy at each phase of illness, and outcome of ASCT were assessed. RESULTS: Patients (MPN details): Thirteen patients (8 male, 5 female, median age at diagnosis of MPN 42 years in those who underwent ASCT and 64 years in those who did not receive ASCT (combined median 53 years, range 26–70)) were identified who met the inclusion criteria, of whom 2 had ET, 4 PV, 2 Post-ET MF, 1 Post-PV MF and 4 PMF. Jak2-V617F mutation was present in 7 of 8 patients tested. Treatments used during the MPN phase included hydroxyurea in 9 (+ busulfan in 1 and + anagrelide in 1), and thalidomide/prednisone in 2 (two patients received no treatment prior to MPN-BP). Patients (MPN-BP details): Transformation of an MPN to blast phase (from diagnosis of MPN) occurred after a median of 11 years in those who underwent ASCT and 8 years in non-ASCT (range 3 months to 30 years). At the time of MPN-BP diagnosis, 9 patients had an abnormal karyotype, 3 with complex karyotypes, 3 with trisomy 8 (sole abnormality), 1 with del(7q), 1 with del(13q). Leukemic induction consisted of standard anthracycline/cytarabine combination therapy (+/− etoposide), except for one patient received a study medication voreloxin. One patient who did not receive ASCT had remission after induction, but later expired from relapse, two expired soon after leukemic transformation, and two were too ill to receive induction. In the ASCT group (N=8), 5 patients achieved complete remission (CR) of their leukemia/return to MPN chronic phase (one of the five patients required a second induction to achieve CR), while 3 patients were considered primary induction failures due to persistence of > 5% blasts in the blood (2) or marrow (1) at the time of pre-transplant response assessment. The median time from diagnosis of MPN-BP to ASCT was 128 days. ASCT Details and Outcomes: Patients (median age of 55 years at time of ASCT; range 44–73) underwent ASCT (all HLA identical, 3 matched unrelated donors, 5 matched sibling donors) with either reduced intensity conditioning (n=6) or fully myeloablative conditioning (n=2). After a median follow-up of 488 days (range 127 – 1206), 6 of 8 patients are alive and free of disease. MPN-BP recurred in two patients at day 69 and 77 post-transplant; both patients eventually died of progressive leukemia, one after a second transplant. Acute GVHD occurred in 3 patients (1 grade III, 2 grade II), and chronic GVHD in 4 (2 mild, 2 moderate). All five patients who achieved CR (marrow and PB blasts < 5%) after induction therapy remain in continuous CR, while 2 of the 3 patients with evidence of persistent leukemia relapsed and died of MPN-BP. No patient died of transplant-related causes and all patients engrafted promptly. CONCLUSION: Rapid induction followed by ASCT can offer a curative path for individuals with MPN-BP. Although limited by small numbers, our data suggest that leukemic clearance (marrow blast percentage < 5%) prior to ASCT is associated with improved outcome. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding.

Abstract Abstract 1977 Introduction: Transplant options are limited for adult patients (pts) who lack a fully matched related or unrelated donor. We hypothesized that in-vivo T-cell depletion with r-ATG would allow safe allo-SCT from mismatched, unrelated donors, thus expanding the potential donor pool for pts with hematologic malignancies who require allo-SCT. Patients and Methods: Thirty seven adult pts (age 20 – 70, median 45) underwent a first unrelated, mismatched, allo-SCT between 1/1/2006 and 6/30/2011 at Mayo Clinic Arizona for hematologic malignancy (35 PBSC, 2 marrow). All pts had at least a one allele or one antigen mismatch (MM) at HLA-A, -B, -C, or -DRB1, and all except one pt received r-ATG as part of the GVHD prophylaxis strategy (dose range 2.5 – 10 mg/kg in daily dose of 2.5 mg/kg depending on degree of mismatch, with the last dose generally given on day −1). One pt received Campath after experiencing anaphylaxis to r-ATG. Pts were transplanted for acute myeloid leukemia (n = 19; 10 CR1, 6 CR2, 3 other), acute lymphoblastic leukemia (n = 8; 4 CR1, 4 CR>/= 2), chronic myeloid leukemia (n = 1), myelodysplastic syndrome (n = 5), or non-Hodgkin lymphoma (n = 4). Conditioning was myeloablative in 20, reduced intensity in 16, and non-myeloablative in 1. Mismatches were as follows: 1-allele MM (n = 7); 1 antigen MM (n = 15); 2 allele MM (n = 4); 1 antigen, 1 allele MM (n = 7); and 2 antigen MM (n = 4). Additional GVHD prophylaxis included tacrolimus plus either methotrexate (n =21), mycophenolate mofetil (n = 14), or other (n = 2). Results: The median follow-up for surviving pts is 12 months. As of 6/30/11, 31 pts were alive, and 6 had died of the following causes: multiorgan failure (n = 1), relapse (n = 3), and veno-occlusive disease (n = 2). To date, there have been no deaths related to acute or chronic GVHD. The 1- and 2-year estimated rates of overall survival are 84.5%/78.8% (Fig. 1); of progression-free survival 79.7%/72.0%. The estimated rate of relapse at 1 and 2 years is 11.8%/18.7%, and of non-relapse mortality 8.1%/10.5%. Four pts (10.8%) have developed severe (grades III-IV) acute GVHD by day 100 (days 19, 27, 30, 43; one pt after withdrawal of prograf due to transplant-associated microangiopathy). No late onset severe acute GVHD has been seen. Moderate to severe NIH-defined chronic GVHD occurred in a single pt at risk (cumulative incidence estimate 2.4% at 1 year, 4.7% at 2 years; Fig. 2). Four pts have reactivated EBV, with one developing PTLD (all have been treated with Rituximab). CMV reactivation was seen in 24 pts (65%), CMV disease in 4, with no deaths directly related to CMV. Conclusions: In vivo T-cell depletion with r-ATG abrogates severe acute and chronic GVHD, and allows use of mismatched unrelated donors for allo-SCT in adult pts with otherwise incurable hematologic malignancies. Long-term survivors are generally free of severe chronic GVHD, with good quality of life. There does not appear to be an increased incidence of disease relapse, and non-relapse mortality is low. This approach is safe, effective, and considerably expands the donor pool for adult pts who require allo-SCT. Disclosures: Reeder: Celgene: Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Novartis: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding.

Abstract Abstract 4527 Introduction: The prognosis for pts with intermediate or high risk AML remains dismal, with relapse rates typically in the 60–80% range after treatment with chemotherapy alone. While allo-SCT can decrease the risk of relapse to 10–20%, widespread use of this modality is limited by relatively high rates of non-relapse mortality (NRM), often due to severe acute and/or chronic GVHD. Attenuation of severe GVHD, without a concomitant increase in relapse or NRM, should improve outcomes and result in cure of a larger fraction of AML pts. We therefore investigated the use of in-vivo T-cell depletion with r-ATG in pts with intermediate- or high-risk AML but without active leukemia at the time of allo-SCT. Patients and Methods: Pts (n = 43) were included in this retrospective analysis if they were between 18 and 65 years of age and had no evidence of active AML at the time of allo-SCT (see Table). All pts had 1 or more high-risk features: 1) adverse or intermediate risk cytogenetics (without NPM1 mutation if cytogenetically normal); 2) therapy-related or secondary AML; 3) high WBC count at diagnosis; 4) failure to achieve CR after 1 cycle of induction; or 5) not in CR1 at allo-SCT. Among the 43 pts, 10 received grafts from related donors, 14 from 10/10 matched unrelated donors (URDs), and 19 from mismatched URDs (9/10, n = 11; 8/10, n = 8). All pts received r-ATG according to institutional standard operating policy, with doses ranging from 2.5 – 10 mg/kg depending on donor type and degree of mismatch. All transplants were performed using PBSC. Additional GVHD prophylaxis included tacrolimus plus either methotrexate or mycophenolate mofetil. Results: The median age was 47 (range 20 – 65), and median follow-up for surviving pts is 12 (range 1 – 66) months. As of 8/5/11, 39 pts were alive, and 4 had died from multiorgan failure (n = 1), relapse (n = 1), GVHD (n = 1), and veno-occlusive disease (n = 1). The 2-year estimate of PFS is 84.7% (Fig. 1). The 2-year cumulative incidence of relapse is 6.8% (2 pts, days 97 and 147), and of non-relapse mortality 9.4%. Three pts developed severe (grades III-IV) acute GVHD by day 100 (cumulative incidence 4.6% at day 100) with no additional cases of severe acute GVHD beyond day 100. To date, 4 pts have developed moderate/severe chronic GVHD (cumulative incidence 16.8% at 2 yrs), with one death at day 344 related to complications of acute and chronic GVHD. CMV reactivation occurred in 29 pts (56%), with no deaths related to CMV. Three pts have reactivated EBV, with one case of PTLD (all treated with Rituximab). Conclusions: In this retrospective analysis of single center data, the inclusion of r-ATG in the GVHD prophylactic strategy appeared to significantly attenuate the incidence and severity of both acute and chronic GVHD. Although follow-up is relatively early, the incidence of relapse and NRM does not appear to be increased compared to contemporaneous pts treated without ATG. Given that almost half of the pts received grafts from mismatched URDs, this abrogation in risk of GVHD is significant and clinically relevant. While randomized studies are needed, these data suggest that in-vivo T-cell depletion with r-ATG ameliorates severe GVHD, without increasing relapse or non-relapse mortality, in AML pts without overt leukemia at the time of allo-SCT. Using this strategy, cure rates of 70 – 80% may be realistic and attainable for younger (</= age 65) AML patients who achieve a leukemia-free state and who have a reasonably matched related or unrelated donor. Disclosures: Reeder: Celgene: Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Novartis: Research Funding.