Wu, Wenting

2019 Background: The mammalian target of rapamycin (mTOR) functions within the PI3K/Akt signaling pathway as a critical modulator of cell survival. We previously demonstrated significant synergy of the mTOR inhibitor sirolimus with RT in glioma xenografts. Methods: The standard cohorts of 3 design was applied with dose escalation of weekly IV CCI-779 in combination with standard TMZ/RT. CCI-779 was given during both RT (60 Gy)/TMZ (75 mg/m2 daily) and adjuvant TMZ (200 mg/m2 daily x 5 every 28 days). Results: A total of 17 patients were enrolled. CCI-779 therapy during RT/TMZ was well tolerated at dose level 0 (25 mg CCI-779, n = 3) and dose level 1 (50 mg CCI-779, n = 6) with 1 of 9 patients experiencing a DLT (Gr 3 fatigue). Dose level 2 (75 mg CCI-779) exceeded the maximally tolerated dose with two of six patients with DLT (<75% CCI-779 delivered; Gr 4 dyspnea). Despite reasonable tolerance during RT/TMZ, the overall regimen was associated with a high rate of infection associated with lymphopenia. After a patient died from PCP on cycle 2 of adjuvant TMZ/CCI-779, antibiotic prophylaxis was mandated. Two other patients died of gram-negative sepsis despite prophylaxis: one after their first dose of CCI-779 and one during cycle 4 of adjuvant therapy. In contrast to our 18% grade 5 infection rate, only 4% grade 3 (no grade 4/5) infections were observed in 26 other CTEP-sponsored clinical trials involving 1,006 patients treated with CCI-779. Results from translational studies evaluating the effects of treatment on immune function will be presented. Further infections were avoided on this trial after CCI-779 therapy was limited to RT/TMZ. Conclusions: Although CCI-779 in combination with RT/TMZ was well-tolerated, adjuvant therapy with TMZ/CCI-779 was associated with an increased risk of opportunistic infections. [Table: see text]

Abstract BACKGROUND: We have previously studied and reported that the combination of pentostatin (P, 2 mg/m2), cyclophosphamide (C 600 mg/m2) and rituximab (R 375 mg/m2) in previously untreated CLL is highly effective with an overall response (OR) rate of over 90% and a complete response rate (CR) of 41% (Blood109:405–411, 2007). We also found that this regimen can be effective even in older patients (&gt;70 y), those with elevated beta-2 microglobulin levels, and patients with mildly reduced creatinine clearances (Cancer. 109:2291–2298, 2007). To determine whether similar benefit could be achieved without inclusion of an alkylating agent, we conducted a follow-up trial testing pentostatin and rituximab without cyclophosphamide and employing a higher pentostatin dose (4 mg/m2). METHODS: Eligible pts had documentation of active CLL by standard NCI-WG criteria, and were previously untreated. Treatment schema consisted of 6 cycles of pentostatin (4 mg/m2) and rituximab given every 21 days. Pentostatin was given on the first day of each cycle following infusion of rituximab. Rituximab was given at 100mg/m2 IV at day 1, then 375 mg/m2 IV on days 3 and 5 of the first treatment cycle. During cycles 2 to 6, Rituximab was given at 375 mg/m2 as a single IV infusion day 1 of week 4, 7, 10, 13 and 16. All patients were staged two months after completion of the 6 cycles of PR using the NCI-WG criteria. PATIENT CHARACTERISTICS: Overall, 33 patients were enrolled at Mayo Clinic and Ohio State University between July 2005 and February 2008. All 33 were eligible: 82% male, median age 65 (range: 45–81), with 9 (27%) being 70 years or older. 76% had a baseline ECOG PS of 0, and the rest were ECOG PS 1. Overall, 36% of patients had intermediate Rai risk (stage I–II) and 63% high Rai risk (stage 3–4) disease. Prognostic testing revealed that 36% were CD38+, 50% were Zap-70 +, and 39% had an unmutated IgVh status. Chromosome analysis by FISH found that 99% had detectable FISH panel defect, including 61%, 27% and 3% of patients with 1, 2, or 3 FISH detects, respectively. RESULTS: 28 of 33 patients (85%) completed therapy. While on treatment, 6 pts (18%) had a dose held or modified with 4 of these delays due to hematologic AE. For adverse events deemed at least possibly related to treatment, 4 (12%) pts experienced grade 3+ hematologic toxicity and 5 (15%) experienced grade 3+ non-hematologic toxicity. Out of all 33 enrolled patients, the overall response rate was 79% with 10 CR, 6 nPR, and 10 PR. At the time of this analysis, 29/33 patients are still alive with a median follow-up time of 14 months on surviving patients. To date 17/33 (52%) of patients have progressed with an estimated median time to progression of 12 months (95% CI: 8.5–21 months). 13/26 responders have progressed. Median duration of response is 12.5 months ((95% CI: 11–21 months). Finally, since eligibility were nearly identical and enrollment accrued at the same two academic centers, we compared the patient characteristics, response rates, and PFS of the 33 patients treated with PR to the 64 patients previously treated on our PCR trial. Patients in the two studies were generally similar with respect to demographic and prognostic characteristics, although patients in the PR trial had higher WBC and were less likely to be IgVH unmutated (Table). Although the differences in ORR and CR rate were not significantly different, the PFS appeared to be inferior in patients treated with PR as compared to PCR (12 months vs. 31 months; p=0.003). CONCLUSION: Although the PR regimen achieves a high OR response rate, the PFS appears inferior to PCR therapy. These findings suggest that increasing the purine nucleoside analogue dose does not eliminate the need to include cyclophosphamide in chemoimmunotherapy for patients with CLL. PCR Trial N=64 PR Trial N=33 P value Age, median(range) 63 years (38–80) 65 years (45–81) 0.34 ≥70 years(%) 28% 27% Male 77% 82% 0.61 Rai stage 0 5% 0 0.46 Rai stage I–II 42% 36% Rai stage III–IV 53% 64% White Cell Count, median(range) 79 × 109/L (11–519) 127 × 109/L (8–430) 0.04 &lt;50 × 109/L 36% 28% 50–149 × 109/L 44% 25% &gt;150 × 109/L 20% 47% Serum B2-microglobulin, median(range) 3.97 (1.8–13.5) 3.80 (2.0–8.2) 0.81 &gt;2 × Upper Limit Normal(%) 57% 58% CD38 Positive 34% 36% 1.00 ZAP-70 Positive 36% 50% 0.26 IgVH Unmutated 71% 39% 0.004 FISH Normal, 11% 9% 13q- 35% 42% +12 21% 24% 6q- 2% 0 11q- 22% 18% 17p- 6% 3% other 3% 3% Overall Response Rate 91% 79% 0.12 Complete Response Rate 41% 30% 0.38 Median PFS 31 months 12 months 0.003

Abstract Background: CLL is still an incurable lymphoid malignancy. The current standard of care is to treat only patients with obvious clinical progression as defined by the National Cancer Institute Working Group in 1996 (NCI–WG 1996). High risk CLL can be identified at diagnosis by a variety of tests including fluorescence in situ hybridization (FISH), immunoglobulin heavy-chain variable region (IgVH) analysis, and expression of ZAP-70 or CD38. With this information we can identify patients with high risk, early stage disease who are candidates for novel low toxicity therapies that could alter the natural course of their disease. Our hypothesis was that combination monoclonal antibody (MoAb) therapy using alemtuzumab and rituximab would significantly reduce the high risk clone in early stage CLL. Methods: This phase II trial was conducted with IRB approval and accrued the planned 30 patients between January 2005 and July 2007 at Mayo Clinic Rochester. The study enrolled consenting patients with Rai stage 0–II CLL without NCI–WG 1996 criteria for treatment who had high risk CLL as defined as one or more of the following 17p13–, 11q22–, unmutated (UM) IgVH (&lt; 2%) and expression of ZAP–70 (≥ 30%) and/or CD38 (≥20%). Treatment was one 30 day cycle (alemtuzumab 3 mg, 10 mg, 30 mg days 1–3 then 30 mg 3 × week × 4 weeks with all doses subcutaneously and rituximab at 375 mg/m2/week IV × 4 doses from day 8). Patients received 7 days of allopurinol and antimicrobial prophylaxis against PCP and herpes virus infections for 7 months. CMV testing by PCR was done weekly during treatment, then monthly × 6. Results: All 30 patients have completed therapy and 27 have been evaluated for response. The median age of these 27 patients was 62 yr (range 29–77) with 8 patients &gt; 70 years. There was a male predominance (67%) with median time from diagnosis to treatment of 0.7 yr (range 0.1 – 6.1). Stage (Rai) at the start of therapy was 0 in 7 (26%), I in 19 (70%), and II in 1. High risk markers were 17p13– in 9 (33%), 11q22– in 7 (26%), UM IgV and expression of either ZAP–70 or CD38 in 11 (41%). All 27 patients completed therapy without interruption. Non hematological grade 3–4 toxicity occurred in 3 patients (2 drug reactions caused by SMX/TMP, 1 CMV reactivation responsive to IV therapy). Response evaluation at 2 months after completion of therapy using NCI–WG 1996 criteria showed an ORR of 93% with 12 (44%) CR, 8 (30%) nPR, and 5 (19%) PR. Two (7%) patients had disease progression. Median duration of follow up was 14.1 months (range 1.9 – 27.2). Median time to disease progression in the 25 responding patients was 14.4 months (95% CI 5.9 – 22.4). Seven (26%) patients have received subsequent treatment for CLL (median 5.2 months, range 2.4 – 20.1). A minimal residual disease assay using 3-color flow cytometry on peripheral blood was negative in 6 of the 7 patients with CR who had no evidence of residual CLL on immunohistochemical examination of the bone marrow. These 6 patients all remain in sustained CR (median follow up 15 months, range 2 – 27.2). Conclusion: Alemtuzumab and rituximab is an effective and tolerable therapy in patients with high risk early stage CLL. A randomized controlled trial is now required to test if this intervention is better than the standard observation approach. In addition, this combination MoAb regimen could be used as a platform to develop even more effective combination treatments for patients with CLL.

Abstract Myeloid cell factor-1 (Mcl-1) is an anti-apoptotic member of the Bcl-2 protein family that associates with tumor cell survival and drug resistance in chronic lymphocytic leukemia (CLL). Increased Mcl-1 expression is associated with failure to achieve remission after chemotherapy with fludarabine and chlorambucil in CLL patients. However, the influence of Mcl-1 expression has not been examined in CLL trials using treatment regimens that contain rituximab, which has shown substantially improved outcomes for a large subset of patients and have become a mainstay in the therapy of newly diagnosed CLL. We previously reported that combination chemoimmunotherapy with pentostatin, cyclophosphamide, and rituximab (PCR) has significant clinical activity with low accompanying toxicity in previously untreated CLL patients, and is especially well tolerated in older patients in whom the use of fludarabine may be associated with prohibitive toxicities. As part of this study, we prospectively investigated association of Mcl-1 protein expression with response and progression-free survival. Eligible patients received a regimen consisting of pentostatin (2 mg/m2), cyclophosphamide (600 mg/ m2), and rituximab (375 mg/m2) given intravenously on day 1 of a 21-day cycle for a maximum of 6 cycles. Responses were assessed according to NCI 1996 criteria and included bone marrow evaluation and two-color flow cytometry two months after completion of therapy. Flow cytometry-negative status was defined as less than or equal to 1% CD5+/CD19+ cells. Of the 64 patients evaluated in this trial, clinical responses were seen in 58 (91%), with 26 (41%) complete responses (CR), 14 (22%) nodular partial responses (nPR), and 18 (28%) partial responses (PR). Lysates from peripheral blood cells obtained pre-treatment were analyzed for Mcl-1 expression by immunoblot. Mcl-1 as a continuous variable was not found to be associated with other commonly described risk factors. However, Recursive Partitioning Analysis (RPA) was devised employing Mcl-1 expression as a continuous variable, which revealed an optimal cut point of 0.85. At this cutoff, flow cytometry-negative status was significantly different between the two groups (p=0.01) and median PFS was significantly higher (p=0.02) in patients with Mcl-1 levels of &lt;0.85 (50.8 vs. 18.7 months). No difference by Mcl-1 expression was noted in other pre-treatment or response parameters. Our data describes the first prospective validation of Mcl-1 over-expression adversely influencing both the likelihood of attaining a flow cytometry-negative complete remission and extended progression free survival. Mcl-1 expression was also independent of other risk factors, indicating additional benefit for this measure in assessing patients. Mcl-1 expression may therefore predict poor response to chemoimmunotherapy, and these findings advocate pursuing therapeutic agents targeting this important anti-apoptotic protein.

2031 Background: The mammalian target of rapamycin (mTOR) functions within the PI3K/Akt pathway as a critical modulator of cell survival. Preclinical studies in GBM indicate that the combination of mTOR inhibitors, such as everolimus (RAD001), with either radiation therapy (RT) or temozolomide (TMZ) provide increased tumor cell killing. Methods: Newly diagnosed GBM pts were eligible for the study. RAD001 was dosed orally at 70 mg/week weekly, starting 1 week prior to RT/TMZ, and continued throughout RT/TMZ, adjuvant TMZ and then until progression. This was a single arm phase II design powered to detect a true overall survival at 12 months (OS12) of 73% (vs 58% in historical controls). Secondary endpoints were toxicity, response rate, and time to progression (TTP). A subgroup of patients with measurable residual disease were eligible for the PET imaging component of the study, consisting of an 18FLT-PET/CT scan performed before and after the initial two doses of RAD001 but before the first dose of RT or TMZ. Results: 103 patients were accrued to phase II of which 100 were evaluable. The median age was 60.5 years (23-81), median ECOG PS was 1, 46 patients had GTR, 33 STR, and the remainder had biopsy at diagnosis. Treatment tolerance was acceptable: 17% patient had at least one grade 3 hematologic toxicity; 14% had at least one grade 4 hematologic toxicity, 42% had at least one grade 3 non-heme toxicity, while 12% had at least one grade 4 non-heme toxicity. No increased incidence of infectious complications was observed and there were no treatment related deaths. Median PFS was 5.3 months (1.3-21.4), with 22 patients progression free. Mature OS data will be available at the meeting. MGMT methylation status analysis is ongoing. Of the pts who had evaluable FLT-PET data, three of eight (37.5%) had a drop in SUVmax >25% after two treatments of RAD001. Conclusions: RAD001 with standard of care chemoradiation had moderate toxicity. Serial 18FLT-PET was feasible for evaluating drug-induced changes in tumor proliferation following RAD001. Final outcome data and association of MGMT status with outcome will be reported at the meeting.

2004 Background: With the approval of novel agents for glioblastoma (GBM) treatment, reliable historical outcome data for the common phase II endpoint of progression free survival (PFS) is not available. In particular, the association between progression and overall survival (OS) has not been evaluated after temozolomide (TMZ) became the standard therapy for newly diagnosed GBM. Methods: Datasets from 5 TMZ-including NCCTG clinical trials in newly diagnosed GBM (n=325, 2005-2011, 1 phase I only and 4 phase I and single arm phase II trials) were pooled and analyzed to evaluate the individual level correlation between PFS and OS using correlation coefficient, landmark analyses, and time-dependent variable analyses. A historical control group was constructed by pooling datasets from 12 pre-TMZ era NCCTG clinical trials in the same patient population (n=1359, 1980-2004). Each of the 5 newer trials was compared to the control group to estimate the treatment effect (hazard ratio) on PFS and OS, which were analyzed to evaluate the trial level correlation between PFS and OS using correlation coefficient and weighted linear regression. Results: The estimated correlation coefficient between PFS and OS at individual patient level is 0.75 (95%CI, 0.7 to 0.8). The estimated hazard ratios of death in the landmark analysis at 4 and 6 months are 2.15 (95%CI, 1.47 to 3.15) and 2.17 (95%CI, 1.57 to 3.12), respectively, and the estimated hazard ratio of death is 10.1 (95%CI, 6.6 to 15.4) when progression is treated as a time-dependent variable. For trial level correlation (against the historical control group), the estimated correlation coefficient between HRos and HRpfs is 0.51 (95%CI, -0.67 to 0.96), with moderate prediction: the predicted HRos is very close to the observed HRos in 4 of 5 cases, however the predicted HRos is significantly different from 1 in only 2 out of 5 cases due to small sample size in other 3 cases. Conclusions: PFS and OS are highly associated at the individual patient level but only moderately at the trial level, the latter possibly due to small sample size in some of the trials. Additional validation in other trials could support use of PFS as a primary endpoint for randomized phase II trials in GBM.

2046 Background: Vorinostat (VOR) is a histone deacetylase inhibitor that represents a rational targeted agent in GBM treatment. Given its single-agent activity in recurrent disease (Galanis,et al, 2009) and radiosensitizing properties, this phase I/II trial was designed to test the addition of VOR to standard chemoradiation in newly diagnosed GBM patients (pts): the phase I portion of the trial is the focus of this report. Methods: A standard cohorts of three design was used to assess the safety of VOR in combination with RT and concomitant TMZ and establish the phase II dose of the combination. VOR was given orally days 1 - 5 every wk beginning with the first dose of RT (total dose 60 Gy) and (75mg/m²/day). Following a 4 - 6 week rest, pts received up to 12 cycles of standard adjuvant TMZ in combination with VOR on days 1-7 and 15 – 21 of each cycle; dose was based on NABTT trial 04-03 (Lee, et al, 2012). Results: The phase I component is complete with 15 pts, 12 pts at dose level 0 (VOR 300 mg/day days 1 - 5, weekly x 6 wks), and 3 pts at dose level 1 (VOR 400 mg/day, days 1 – 5 weekly x 6 wks) in combination with RT/TMZ. Dose limiting toxicity (DLT) in dose level 1 included grade 3 fatigue in 2 pts, grade 3 wound dehiscence in 1 pt, and grade 4 neutropenia and thrombocytopenia in 1 pt. In dose level 0, 1/6 pts had DLT (gr 3 dyspnea). An MTD expansion cohort of 6 additional patients was added to dose level 0; one patient experienced grade 4 thrombocytopenia and grade 3 fatigue, and 1 patient experienced grade 3 febrile neutropenia. In the 12 pts treated in the phase II dose, most common toxicities were hematologic, including lymphopenia (gr 3/4 in 66.7%), thrombocytopenia (gr 3 in 16.7%, gr 4 in 16.7%) and neutropenia (gr 3 in 16.7%, gr 4 in 8.3%). Grade 3 fatigue was observed in 8.3% of the pts. Conclusions: MTD for VOR in combination with TMZ/RT in newly diagnosed GBM patients is 300 mg/d, days 1 - 5 weekly during RT. Toxicity was primarily hematologic. This dose was used in the recently completed phase II trial of the combination (110 pts). RNA expression profiling in patient samples is in process to assess vorinostat responsive signatures observed in preclinical models. Clinical trial information: NCT00731731.

7030 Background: JAK2V617F occurs in approximately 50% of patients with essential thrombocythemia. Qualitative studies of mutation analysis have previously reported an association between JAK2V617F and advanced age, higher hemoglobin level, higher leukocyte count, and lower platelet count. A possible association with thrombotic complication has also been considered. Methods: Allele-specific, quantitative PCR analysis for JAK2V617F was performed on 176 patients with ET, using genomic DNA from archived bone marrow, which was collected within one year (n=72), between 1 and 5 years (n=64), or after 5 years (n=40) of diagnosis. Results: JAK2V617F was detected in 96 patients (55%), in whom mutant allele burden ranged from 1% to 100% (median 6.3%). Neither mutational frequency (p=0.37) nor mutant allele burden (p=0.62) was affected by the timing of bone marrow sample collection. Presence of JAK2V617F was significantly associated with higher hemoglobin level (p<0.0001), lower platelet count (p=0.001), higher leukocyte count (p=0.008), increased incidence of venous thrombosis occurring after diagnosis (p=0.02), and older age at diagnosis (p=0.03). All but age retained significance in multivariable analysis. In mutation-positive patients (n=96), JAK2V617F allele burden clustered between 1% and 22% in 94 cases, in whom it correlated directly and significantly with platelet and leukocyte counts, palpable splenomegaly at diagnosis, and venous thrombosis occurring after diagnosis. Conclusions: JAK2V617F allele burden imparts additional phenotypic effects in ET. No significant financial relationships to disclose.

2075 Background: Multiple variables may impact endpoints used to assess therapeutic efficacy for patients with recurrent gliomas. To identify prognostic factors for each of 3 outcome variables, a master analysis file was constructed by pooling datasets summarizing key baseline factors and outcomes obtained in 15 North Central Cancer Treatment Group (NCCTG) trials (n=583, 1980–2004) and 12 North American Brain Tumor Consortium (NABTC) trials (n=596, 1998–2002). Methods: In addition to traditional variables (gender, age, performance score (PS), race, extent of primary resection, year of study entry, last known histology, time since initial diagnosis, baseline steroid use, prior chemotherapy (Y/N), prior nitrosoureas, baseline anticonvulsant use), we investigated prior t (TMZ), number of relapses, academic vs. community site and low grade at initial diagnosis. Outcome variables were: (1) overall survival (OS), (2) progression free survival (PFS) and (3) PFS6 = proportion of patients alive and progression-free 6 months after start of treatment. For all 3 endpoints, Classification and Regression Tree (CART) models and bootstrap samples were used to identify prognostic variables and to look for evidence of interactions among the independent variables affecting outcome. Results: For all outcomes the initial CART analysis selected last known grade (4 vs. 3) as the most important variable. Additional factors selected as predicting poor prognosis differed with grade and outcome measure and included prior TMZ, longer time since primary diagnosis, older age and poor PS. Community vs. academic was not a strong predictor in any of the models nor was low grade at initial diagnosis. Additional analyses are planned to better describe the impact of all the variables on outcome, including use of Cox models and logistic models considering all baseline variables with backwards selection. Conclusions: The results from analyses to date are consistent with current thinking that last known histology (grade) is an important factor. Time since initial diagnosis is likely a surrogate for number of relapses. More definitive conclusions await the completion of ongoing analyses. No significant financial relationships to disclose.

Abstract BACKGROUND: Information regarding risk factors for leukemic transformation (LT) in primary myelofibrosis (PMF) is limited, although both leukocytosis and abnormal cytogenetics have previously been implicated. The current retrospective study examines clinical variables at diagnosis as well as specific treatment modalities for their effect on LT in PMF. METHODS: Diagnoses of PMF and LT were based on World Health Organization criteria. In addition, study inclusion required availability, for review, of bone marrow histology and clinical data obtained at or within 6 months of diagnosis but prior to treatment intervention. Statistical methods used were standard and included Cox regression analysis of leukemia-free survival (LFS). RESULTS: A master database of PMF patients seen at the Mayo Clinic from 1976 through 2006 was queried to identify 311 patients who fulfilled the aforementioned stipulated criteria for study inclusion; median age was 57 years and 41% were females. At presentation, 30% of the patients displayed a hemoglobin level (Hgb) of < 100 g/L, 20% a leukocyte count of < 4 or > 30 x 109/L, 18% a platelet count of < 100 x 109/L, 12% an absolute monocyte count (AMC) of ≥ 1 x 109/L, 28% hypercatabolic symptoms and 35% a peripheral blood (PB) blast percentage of ≥ 1; 27 patients (9%) had a PB blast percentage of ≥ 3. Dupriez prognostic scoring system distribution for high, intermediate, and low risk disease was 30 (10%), 94 (30%), and 187 (60%) patients. Among 182 and 139 evaluable patients, 74 (41%) and 80 (58%) displayed cytogenetic abnormalities and JAK2V617F, respectively. At a median follow-up of 27 months (range 0–282), 27 cases (9%) of LT were documented at a median time from diagnosis to LT of 26 months (range 0.8–266). Effect of clinical and laboratory variables at diagnosis on leukemic transformation By univariate analysis, LFS was negatively affected by anemia (p=0.04), leukocytosis (p=0.04), PB monocyte count ≥ 1 x 109/L (p=0.02), platelet count of < 100 x 109/L (p=0.004), hypercatabolic symptoms (p=0.03) and PB blast percentage of ≥ 3 (p<0.0001); LFS was not affected by PB blast percentage of > 1 but < 3 (p=0.49). By multivariable analysis, significance was sustained only for PB blast percentage of ≥ 3 (p = 0.0002) and platelet count of < 100 x 109/L (p = 0.02) with hazard ratios (HR) of 5.8 and 2.8 and 95% confidence intervals (CI) of 2.3–14.6 and 1.2–6.6, respectively. The presence of JAK2V617F did not affect LFS (p=0.98). Effect of specific treatment on leukemic transformation By univariate analysis, LT was significantly associated with history of splenectomy (p=0.01) and treatment with erythropoiesis stimulating agents (ESA; p=0.004), danazol (p=0.007), and androgens (p=0.03) but not with hydroxyurea (p=0.17), interferon alpha (p=0.95), thalidomide (p=0.26) or other drugs. On multivariable analysis, significance was sustained for both ESA (p = 0.005; HR 3.1, CI 1.4–6.8) and danazol (p = 0.01; HR 3.4, CI 1.3–8.5), even when the aforementioned prognostic indicators at diagnosis were added as covariates to the multivariable model. CONCLUSIONS: The current study identifies PB blast percentage of ≥ 3% and platelet count of < 100 x 109/L, at presentation, as independent risk factors for LT in PMF. Unexpectedly, the study also revealed an association between LT and treatment history with ESA or danazol. These observations are intriguing, considering recent reports on the possible harmful effects of ESA in certain solid tumors.