Hogan, W. Michael

Abstract Introduction: CSF3R mutations (CSF3RMUT), most commonly T618I, represent the defining genomic alteration in chronic neutrophilic leukemia (CNL), present in ~80% of cases. Despite emerging real-world data, information on treatment outcomes and prognostic factors remains limited due to rarity of the disease. In this two-center retrospective study, we examined clinical and molecular predictors of treatment response, overall survival (OS), and blast transformation (BT) and outcome following allogeneic stem cell transplant (ASCT). Methods: The study was approved by the institutional review boards of the Mayo Clinic (USA) and the University of Montreal (Canada). Electronic medical records were reviewed to identify patients with CSF3R mutated CNL at both institutions and extract relevant data. Statistical analyses were conducted using JMP Pro 17.0.0 software (SAS Institute, Cary, NC, USA). Results: Forty-four patients (68% male, median age 68 years [range: 26-93]) were included. At diagnosis, 20 (56%) were asymptomatic, 13 (36%) presented with constitutional/non-specific symptoms, and 20 (50%) had antecedent leukocytosis at a median of 13 months(mo) prior. Splenomegaly (palpable or radiological) was observed in 28 (67%) patients, hepatomegaly in 7 (17%) and lymphadenopathy in 4 (9.8%). Median white blood cell count (WBC) was 52×10⁹/L (range: 17-390). CSF3RMUT/variants included 39 (89%) with T618I (7 of the 39 had additional CSF3RMUT), 2 (5%) with M696T, and 1 (2%) each for I598I, Q739* and T640N. Frequent co-mutations included ASXL1 in 25 (63%) patients, SETBP1 in 14 (36%), and SRSF2 in 8 (31%), with overlapping occurrence; 10 (38%) patients had ≥2 of these 3 mutations. Ten patients (median WBC 29 x10⁹/L [range: 19–58]), were initially observed without treatment for a median of 8.6 mo; 2 remained on observation alone at 46 and 77 mo. Hydroxyurea (HU) alone or in combinations excluding ruxolitinib (Ruxo) was the most common first-line treatment (68%). Second-line therapies included Ruxo (39%), HU (25%), and hypomethylating agents (14%). WBC response (≥50% reduction from baseline) was 78% with HU vs. 60% with Ruxo (p=0.2). WBC response to HU was lower with abnormal karyotype (40% vs. 94%; p=0.02). WBC response to Ruxo was lower with SETBP1MUT (0% vs. 72%; p=0.05) and with male sex (40% vs. 100%; p=0.04). Seven patients underwent ASCT, including 2 after BT; four (57%) of the 7 remain alive, including 2 without evidence of disease (both 45 mo post-ASCT; one harbored ASXL1MUT) and the other 2 with active disease (both harbored ASXL1MUT). Three patients died from veno-occlusive disease (Day+34), CNS relapse with AML (at 105 mo post-ASCT), or unrelated causes (at 44 mo post-ASCT). Median OS was longer in transplanted patients (115 vs 23 mo; p=0.03). At a median follow-up of 44 mo for living patients, disease transformation occurred in 10 patients, including 7 with BT (6 with T618I, 1 T640N) and 3 with chronic myelomonocytic leukemia (2 M696T, 1 T618I). BT rate at 2, 3, and 5 years was 15%, 31%, and 43%, respectively. Univariate analysis (UVA) identified male gender (p<0.01), >5% immature WBCs (p=0.02), platelets <160×10⁹/L (p=0.04), higher WBC (p=0.02), and ASXL1 or SETBP1 mutation (p<0.01) as risk factors for BT. On multivariable analysis (MVA), only the latter remained significant. Median OS was 26 mo (95% CI: 21-43) for the entire cohort; 24 mo for patients with T618I CSF3RMUT vs 53 mo with other CSF3RMUT, p=0.1. In UVA, age >60 years (HR 5.0, p=0.03), platelets <160×10⁹/L (HR 3.4, p=0.006), WBC >50×10⁹/L (HR 2.6, p=0.02), and ASXL1 or SETBP1 mutations (HR 4.2, p=0.01) were associated with shorter OS. In MVA, age >60 (HR 6, p=0.03), WBC >50×10⁹/L (HR 12, p<0.01), and the presence of ASXL1MUT or SETBP1MUT (HR 9.5, p=0.01) remained significant. Based on the HRs on MVA, one adverse point was allocated for age >60 years, and two adverse points each for WBC >50×10⁹/L and presence of ASXL1 or SETBP1 mutations. Patients were accordingly stratified into low (0-2 points), intermediate (3) and high (4-5) risk groups with corresponding median OS of “not reached”, 29 mo, and 16 mo (p<0.01). Causes of death included disease progression (82%), infection/bleeding (9%), and ASCT complications (9%). Conclusion: The current study highlights the prognostic relevance of “SETBP1 or ASXL1” mutation for both overall survival and risk of blast transformation. The study also signifies variable natural history and potential benefit from ASCT.

Summary In 2014, the International Myeloma Working Group (IMWG) updated the criteria for diagnosing myeloma and added three additional criteria to the traditional Calcium elevation, Renal impairment, Anemia, Bone disease (CRAB) criteria, called the Sixty % marrow plama cells, Light chain ratio >60, Mri demonstates lytic lesions (SLiM) criteria (clonal bone marrow plasma cells ≥60%, involved to uninvolved free light chain ratio (FLCr) ≥100 and >1 focal lesion on magnetic resonance imaging (MRI)). We report on the outcomes of 30 patients who underwent autologous stem cell transplantation (ASCT) where therapy was initiated solely based on SLiM criteria and compared them to a matched cohort of 60 patients whose myeloma‐defining event was CRAB. The SLiM cohort had a shorter median time to neutrophil (15 vs. 16 days, p = 0.049) and platelet (15 vs. 17 days, p = 0.0004) engraftment. The 36‐month overall survival (OS) was 100% in the SLiM group and 93.27% in the control group (95% CI 83.06%–97.42%), with a trend towards longer OS in the SLiM cohort ( p = 0.065). The 36‐month progression‐free survival (PFS) was 91.61% in the SLiM (95% CI 69.93%–97.87%) and 65.95% in the control group (95% CI 52.31%–76.53%). There was no difference in the PFS between the cohorts ( p = 0.414). ASCT is efficacious and safe in MM patients transplanted only due to SLIM criteria. Early intervention in this asymptomatic cohort did not appear to result in deeper responses or better PFS compared to outcomes in symptomatic patients.

Abstract Abstract 4213 INTRODUCTION Fanconi Anemia (FA) is a primarily autosomal recessive disorder with a defective DNA repair pathway associated with mutations in any of 13 genes. The majority of patients reported in the literature have one or multiple congenital anomalies, including low birth weight, short stature, café au lait spots, abnormal radii and/or thumbs, structural renal abnormalities, microcephaly, and deafness, among others. About 25% of reported patients had few or none of these findings. The hazard of severe aplastic anemia peaks at 10 years of age, and patients have very high risks of acute myeloid leukemia and specific solid tumors, such as head and neck and gynecologic squamous cell carcinomas. Only six patients have been reported who were diagnosed between 40 and 50 years of age. However, patients may present as adults with neoplasms, or remain asymptomatic and undiagnosed. METHODS We report the diagnosis of FA in the oldest known patient, an asymptomatic 55 year old woman (Case 2), identified only because she was a potential stem cell donor for her 42 year old sister (Case 1) with severe aplastic anemia. RESULTS Case 1 had a history of thrombocytopenia at 26, and anemia and thrombocytopenia during pregnancy; physical exam was normal except for a slightly deformed thumb; blood lymphocyte chromosome aberrations were increased with both diepoxybutane (DEB) and mitomycin C (MMC). The patient died following an HLA-matched bone marrow transplant from a non-FA brother. Case 2, the other of two siblings of Case 1 who were HLA matches, had higher than normal chromosome breakage in blood (3 cells with multiple radials with MMC) but not in the FA range; skin fibroblasts were diagnostic of FA, confirming hematopoietic somatic mosaicism. She had a normal appearance, a history of hypothyroidism and mitral valve prolapse, five pregnancies with five children (one miscarriage, one set of twins), a near normal blood count (Hb 13.3 g/dl, MCV 99 fl, WBC 3500/ul, and platelets 139,000/ul), and was a regular blood donor. Bone marrow cellularity and morphology were normal, but cytogenetics showed a small clone (46,XX,add(11)(q23)[6]/46,XX[14]). Complementation analysis of Case 1 indicated group A (FA-A), and molecular analysis identified two mutations in the FANCA gene. One mutation, p.S1208S (c.3624C>T) was a splice site mutation occurring in exon 36 and has been previously described. The second mutation was a novel nonsense mutation in exon 23, p.S674X (c.2021C>A). Five siblings had normal breakage results; four were heterozygous for the nonsense mutation and one was negative for both mutations. Case 2, with mosaicism for FA, had the familial splice mutation in both blood and fibroblasts, and the familial nonsense mutation in fibroblasts, but was skewed heavily toward wild-type in blood. cDNA studies confirmed that the predicted splice mutation created an alternate splice site resulting in multiple transcripts, including exon skipping, which varied in different tissues. The molecular mechanism for the loss of the nonsense mutation in the blood is most likely due to back mutation at a hot spot, which occurred in a hematopoietic stem cell which then had a selective growth advantage. CONCLUSIONS Reversion of one FANCA mutation probably occurred in a hematopoietic stem cell which was selected for and repopulated the peripheral blood. A plausible explanation for the lack of FA clinical features is the leaky splice mutation which may provide sufficient levels of protein for normal function in DNA repair. Family members should be tested for FA by chromosome breakage analysis in blood (and/or fibroblasts to identify those who may be mosaics). Those who have FA are at risk of syndrome-specific solid tumors, as well as aplastic anemia, myelodysplastic syndrome, and leukemia, if a non-gene corrected hematopoietic stem cell were to emerge. Even if asymptomatic, they should not be used as stem cell transplant donors for siblings with FA, because they may fail to repopulate the recipient marrow. FA is undoubtedly underdiagnosed in adults at this time. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Voriconazole is a common antifungal medication used in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients. In solid organ transplantation, multiple studies have associated the use of voriconazole with the development of squamous cell carcinoma (SCC) post-transplant, but its association with SCC in allo-HSCT patients is unknown. We sought to determine this association. Methods After IRB approval, Mayo Clinic’s transplant database (2007-2012) was accessed and electronic charts of allo-HSCT patients were retrospectively reviewed. Voriconazole exposure was defined as exposure to voriconazole at any time during treatment of primary disease, prior to or following HSCT. Cumulative voriconazole exposure was defined as total days of voriconazole use following HSCT; days were not required to be consecutive. Two time-dependent voriconazole exposure variables were defined: (1) history of voriconazole exposure (yes/no) over time, and (2) cumulative days on voriconazole over time. Results 404 patients underwent allo-HSCT during this timeframe, and 381 patients (table 1) were included in the final analysis. 23 patients were excluded (8 patients received multiple transplants, 9 patients were treated under pediatric protocols, 6 patients lacked research consent). 312/381 received voriconazole; other antifungal therapy included fluconazole (n=40), posaconazole (n=23), anidulafungin (n=1), and caspofungin (n=5). Median duration of cumulative days of voriconazole was 214 (range 2 -1553). SCC developed in 26/312 exposed to voriconazole and in 1/69 who received alternative antifungals. Cumulative incidence of SCC at 1 year was 3%, 2 years was 8%, 3 years was 13%, 4 years was 14%, and at 5 years was 19% (figure 1). Cumulative days of voriconazole use was found to be a risk factor for the development of SCC, and this relationship persisted in a multivariate model using previously identified risk factors (gender, age at transplant, TBI conditioning regimen, skin cancer pre-HSCT, chronic GVHD) as covariates (HR 1.859 for each 180 days of use, p<0.001). History of prior voriconazole exposure was not associated with an increased risk of SCC after covariate adjustment (HR 2.436, p=0.2369). Conclusion This is the first study to establish cumulative days of voriconazole use as a risk factor for SCC development following allo-HSCT, and may help guide appropriate antifungal prophylaxis in this patient population which is already at an increased risk of developing skin cancers. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2253 Background: Lenalidomide based combinations are among the most common initial therapies for myeloma. Previous studies have suggested that lenalidomide therapy can result in suboptimal stem cell collection in patients eligible to undergo autologous stem cell transplantation, especially older patients after prolonged exposure to the drug. Many salvage approaches are used when attempting repeat stem cell collection in this patient group. Patients and Methods: Two hundred twenty four patients who underwent stem cell collection following lenalidomide-dexamethasone induction from July 2004 and December 2009 were included in the current analysis. Data pertaining to the duration of lenalidomide therapy, stem cell mobilization regimen, and the collection yields were collected from the medical records. Results: The median age at mobilization was 60.6 years (range; 29, 76) and 136 (60%) were male. There were a total of 245 collection attempts from among 224 patients, 21 (9.8%) patients attempting to remobilize after failing to collect the desired numbers of stem cells at the first attempt. We first analyzed the results of the initial collection attempt. The median duration of lenalidomide therapy prior to stem cell collection was 4 months (range; 1, 26). The mobilization strategies were GCSF (Granulocyte Colony Stimulating Factor) alone in 151 (67%) patients, cyclophosphamide (CTX) followed by GCSF in 29 (13%) patients, and GCSF plus AMD3100 in 44 (20%) patients. Among those receiving AMD3100, it was added either due to peripheral blood CD34 cell count not reaching the threshold for initiation of harvest or for poor first day CD34 cells collection in 34 patients and given in a planned fashion in 10 patients. Overall 15 patients (7%) failed to reach the peripheral CD34 cell counts required to initiate apheresis, and among those starting apheresis 6 patients failed to collect at least 2 million CD34 cells/kg; a cumulative failure rate of 9%. Another 18 (8%) patients failed to collect at least 4 million CD34 cells /kg. The CD34 cells yield on day 1, the total yield, number of collections, the average daily yield and the percentage of the targeted cells collected for each mobilization strategy including failure rates are detailed in the table. Twenty-one patients reattempted stem cell mobilization; including 14 that failed a first attempt and 7 did who not achieve the intended goal even though they collected more than 2 million CD34 cells/kg. The mobilization regimens were GCSF alone, CTX + GCSF, GCSF + GM-CSF (Granulocyte Macrophage Colony Stimulating Factor) and GCSF + AMD in 5, 8, 3, and 4 patients respectively. All patients collected at least 2 million CD34 cells /kg and 14 patients (70%) collected more than 4 million CD34 cells /kg. The median CD34 cells collected with the second attempt was 5.4 million/kg (rang; 2, 19.5) bringing the median total collection for these 21 patients to 9.6 million/kg (2.6-19.6). Overall, of the 224 patients studied, all but the 6 patients who failed initially and did not attempt a second collection collected at least 2 million CD34 cells /kg and 197 (88%) collected at least 4 million CD34 cells/kg. Conclusion: While the overall failure rate of stem cell collection in patients receiving initial therapy with lenalidomide is 10%, a risk adapted approach of adding AMD3100 appear to decrease the risk of failure. However, majority of patients failing a stem cell harvest attempt can be salvaged with a second collection allowing these patients to proceed to a stem cell transplant if desired. Disclosures: Gertz: Celgene: Honoraria; Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genzyme: Research Funding. Lacy: Celgene: Research Funding. Dispenzieri: Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Micallef: Genzyme: Membership on an entity's Board of Directors or advisory committees. Kumar: Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding.