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Abstract Abstract 5146 Background: Myelofibrosis (MF) is characterized by splenomegaly, debilitating symptoms, hematologic abnormalities, and shortened survival. COMFORT-I is a Phase III randomized, double-blind, placebo-controlled study of the JAK1 and JAK2 inhibitor ruxolitinib in patients (pts) with MF. The placebo arm of this ongoing study provides a unique population in which to assess the clinical burden of MF in a controlled setting. Methods: 151 pts with intermediate-2 or high-risk primary-MF (PMF), post-polycythemia vera-MF (PPV-MF), or post-essential thombocythemia-MF (PET-MF) who were not candidates for other therapies were randomized to receive placebo in COMFORT-I after a 28-day washout of previous MF therapies. Assessments included MF symptoms measured daily using an electronic diary (modified Myelofibrosis Symptom Assessment Form [MFSAF] v2.0), spleen volume measured every 12 wks by blinded abdominal MRI or CT scans, and laboratory measures at least monthly through wk 24. The Patient-Reported Outcomes Measurement System (PROMISE) Fatigue and Patient Global Impression of Change (PGIC) questionnaires were administered at each visit. Pts with missing data (baseline or post-baseline assessment measured), or pts who withdrew or crossed over to active treatment before a study visit were not included in analyses. Results: 151 pts received 1 or more doses of placebo (median exposure 204 days). The study included 65% high-risk and 35% intermediate-2 risk pts, with a median of 2.5 years since diagnosis. 55% had PMF, 31% PPV-MF, and 14% PET-MF. Regardless of prior MF therapy (57% were on hydroxyurea), there was continual worsening of symptoms over time as assessed by the MFSAF Total Symptom Score (TSS, comprised of scores for night sweats, itching, abdominal pain and discomfort, early satiety and bone/muscle pain) (see Figure). At wk 24, mean/median spleen volume increased by +8.1%/+8.5%, and both intermediate-2 and high-risk pts demonstrated progressive disease over the course of the study. Mean/median PROMIS Fatigue score worsened by 9.1%/6.5%. Mean/median score for the PGIC (a 7-point scale ranging from 1 = very much improved to 7 = very much worse, with 4 = no change) was 4.2/4.0 at wk 24; 19.6% of pts reported feeling much worse or very much worse. Mean/median total body weight changed from 72.0 kg/72.2 kg to 70.1 kg/69.7 kg at wk 24. Hematology assessments (median, baseline vs wk 24) were as follows: hemoglobin, 105 vs 106 g/L; platelets, 233 vs 219 x109/L; neutrophils, 14.8 vs 16.0 x109/L; white blood cell count, 18.4 vs 20.1 x109/L. Two of 151 pts had new-onset (new or worsening) grade 3 or grade 4 thrombocytopenia, and 23/151 pts had new-onset grade 3 or grade 4 anemia. 16 pts met protocol-specified criteria for unblinding and crossover to active treatment before wk 24, which was a 25% increase in MRI-based spleen volume either with or without increased pain or weight loss; thus, mean and median values reported at wk 24 may represent an underestimate of the degree of worsening in disease parameters. Conclusion: The signs and symptoms of MF continued to worsen over a 6-month time frame in this placebo population. The data illustrate the progressive nature of MF and support the need for effective therapeutic interventions. Moreover, treatment benefit must be benchmarked against continual evolution of the disease in the absence of treatment. Early recognition of the debilitating symptoms of MF and intervention with effective therapy to prevent continual worsening of the disease should be strongly considered. Disclosures: Verstovsek: Incyte: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding. Gotlib:Incyte: Consultancy, Research Funding. Levy:Incyte: Employment, Equity Ownership. Gupta:Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Catalano:Incyte: Honoraria; Novartis: Honoraria. Deininger:BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Genzyme: Research Funding. Miller:Incyte: Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau. Winton:Incyte: Consultancy. Arcasoy:Incyte: Research Funding. Lyons:Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Telik: Research Funding; Alexion: Consultancy, Honoraria; Novartis: Research Funding. Vaddi:Incyte: Employment. Erickson-Viitanen:Incyte: Employment. Sun:Incyte: Employment. Sandor:Incyte: Employment. Kantarjian:Incyte: Research Funding; Novartis: Consultancy, Research Funding.

Abstract Background In the primary analysis of the phase III COMFORT-I study, the JAK1/JAK2 inhibitor ruxolitinib (RUX) significantly improved splenomegaly, myelofibrosis (MF)-related symptoms, and quality of life (QoL) measures in patients (pts) with MF versus placebo (PBO). An additional analysis (median follow-up 51 weeks [wks)]) showed RUX was associated with a survival advantage versus PBO (Verstovsek et al. N Engl J Med2012). Longer term follow-up (median 102 wks) showed durable SV reductions and QoL improvements. At this time point, RUX continued to be associated with a survival advantage, despite all pts originally randomized to PBO having discontinued or crossed over to ruxolitinib shortly after the primary analysis (Verstovsek et al. ASH 2012. abstract 800). We report additional longer-term follow-up of pts from COMFORT-I. Methods In COMFORT-I, 309 pts were randomized (1:1) to RUX or PBO. RUX starting dose depended on baseline platelet count (100–200´109/L: 15 mg BID; >200´109/L: 20 mg BID). Doses could be titrated for lack of efficacy or excess toxicity as specified in the protocol. Pts receiving PBO could crossover to RUX after the primary analysis (ie, when all pts completed 24 wks and half the pts completed 36 wks of therapy) or at any time if they met protocol-specified criteria for worsening splenomegaly. The primary endpoint was the proportion of pts who achieved a ≥35% reduction in spleen volume (SV) at wk 24. Symptoms were assessed up to wk 24 using the modified MF Symptom Assessment Form v2.0. QoL continued to be evaluated beyond wk 24 using the EORTC QoL Questionnaire-Core 30 (QLQ-C30). Survival was estimated by Kaplan-Meier analysis according to original randomized treatment. To better understand the effect of crossover on the PBO arm, statistical modeling of survival was conducted using a generalized Gamma distribution. Results Median follow-up was 149 wks at the time of this updated analysis. Of 155 pts originally randomized to RUX, 77 remain on therapy. Of 154 pts originally randomized to PBO, 111 crossed over to RUX; the median time to crossover was 41.1 wks (range, 5.1–65.4). At wk 24, pts originally randomized to RUX had a mean SV reduction of −31.6%; this was durable for pts who continued on RUX, where the mean SV reduction at wk 144 was −34.1%. Fifty-nine percent (91/155) of pts originally randomized to RUX achieved a ≥35% SV reduction at any time during study; for these pts, the probability of maintaining this response for >132 weeks from the time of their initial response was 0.53. Pts originally randomized to RUX who continued on therapy experienced durable improvements in the Global Health Status/QoL and functional domains of the EORTC QLQ-C30. Overall survival favored RUX (HR=0.69; 95% CI: 0.46, 1.03; P= 0.067; Fig 1), with 42 and 54 deaths among pts originally randomized to RUX and PBO, respectively. Modeling of the hazard function of death over time to explore the effect of crossover to RUX in pts originally randomized to PBO showed a decrease in hazard for these pts, which corresponded to an increased proportion of pts crossing over to RUX. In pts originally randomized to RUX who continued on therapy, there was no substantial change in the rate, distribution, or severity of nonhematologic adverse events (AEs) with longer-term therapy; most nonhematologic AEs were grade 1 or 2. Mean and median hemoglobin and platelet count remained stable with longer-term therapy. Consistent with this, the incidence of new onset grade 3 or 4 anemia and thrombocytopenia observed after the first 6 months of RUX therapy decreased relative to that seen in the first 6 months of therapy (Fig 2). With approximately 1 year of additional follow up, 4 new cases of acute myeloid leukemia were reported: 2 pts originally randomized to PBO (376 and 666 days after crossover to RUX) and 2 pts originally randomized to RUX (848 and 1143 days after starting RUX). Conclusions After a median follow-up of 149 wks, the hazard ratio for overall survival favored pts originally randomized to RUX over those originally randomized to PBO, the majority of whom crossed over to RUX. The hazard of death for pts originally randomized to PBO decreased as pts crossed over to RUX. SV reductions and QoL improvements were sustained with longer-term therapy. The incidence of new onset grade 3 or 4 anemia and thrombocytopenia decreased with longer-term therapy. Collectively, these data reinforce the durable efficacy and longer-term safety of RUX in pts with MF. Disclosures: Verstovsek: Incyte Corporation: Research Funding. Mesa:Genentech: Research Funding; NS Pharma: Research Funding; Gilead: Research Funding; Incyte Corporation: Research Funding; Lilly: Research Funding. Gotlib:Incyte Corporation: Travel support, Travel support Other; Incyte Corporation: Membership on an entity’s Board of Directors or advisory committees; Incyte Corporation: Research Funding. Levy:Incyte Corporation: Equity Ownership; Incyte Corporation: Employment. Gupta:Incyte Corporation: Consultancy; Novartis: Consultancy; Inctye Corporation: Research Funding; Novartis: Research Funding; Novartis: Speakers Bureau. Deininger:BMS, ARIAD, NOVARTIS: Consultancy; BMS, NOVARTIS, CELGENE, GILEAD: Research Funding; ARIAD, NOVARTIS: Advisory Boards, Advisory Boards Other. Miller:Novartis: Consultancy; Incyte Corporation: Consultancy; Novartis: Research Funding; Incyte Corporation: Research Funding; Novartis: Honoraria; Incyte Corporation: Honoraria. Talpaz:Ariad: Consultancy; Novartis: Consultancy; BMS: Consultancy; Pfizer: Consultancy; Ariad: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees; BMS: Membership on an entity’s Board of Directors or advisory committees; Pfizer: Membership on an entity’s Board of Directors or advisory committees. Winton:Incyte Corporation: Research Funding; Incyte Corporation: Membership on an entity’s Board of Directors or advisory committees. Arcasoy:Incyte Corporation: Research Funding. Lyons:Lilly: Research Funding; Amgen: Research Funding; Celgene: Research Funding; Incyte Corporation: Research Funding; Gilead: Consultancy; Seattle Genetics: Research Funding; Gilead: Research Funding; Ariad: Research Funding; GlaxoSmithKline: Research Funding; Novartis: Research Funding. Paquette:Incyte Corporation: Consultancy. Raza:Novartis: Speakers Bureau; Onconova Inc: Research Funding. Vaddi:Incyte Corporation: Employment; Incyte Corporation: Equity Ownership. Sun:Incyte: Employment; Incyte: Equity Ownership. Peng:Incyte Corporation: Employment; Incyte Corporation: Equity Ownership. Sandor:Incyte: Employment; Incyte: Equity Ownership. Kantarjian:Ariad: Research Funding; Novartis: Research Funding; BMS: Research Funding; Pfizer: Research Funding.

Abstract Background: Polycythemia vera (PV) is characterized by erythrocytosis, thrombocytosis, and/or leukocytosis and a broad range of disease-related symptoms. In high-risk patients, the most common first-line treatment is hydroxyurea (HU). The open-label RESPONSE trial demonstrated that ruxolitinib (RUX), a JAK1/JAK2 inhibitor, provided superior efficacy compared with best available therapy in patients with PV who were resistant to or intolerant of HU according to modified European LeukemiaNet (ELN) criteria. This study (RELIEF) was conducted in patients receiving a stable dose of HU and who were generally well controlled but reporting disease-associated symptoms, comparing the change in PV-related symptom burden in patients continuing their HU therapy with those switching to RUX treatment. Methods: RELIEF was a randomized, multicenter, double-blind, double-dummy, phase 3b study of patients with PV aged ≥18 years on a stable dose of HU monotherapy and reporting PV-related symptoms. Patients were required to be receiving HU for ≥12 weeks prior to enrollment and on the same dose level for the last 4 weeks, and have a score ≥8 on the Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) cytokine total symptom score (TSS-C). The TSS-C comprised symptoms of itching, tiredness, muscle ache, night sweats, and sweats while awake; each symptom was rated on a scale of 0=absent to 10=worst imaginable, with a maximum TSS-C score of 50. Patients also had to meet one of the following: ≤1 phlebotomy in the previous 6 months or no palpable splenomegaly. Those eligible were randomized 1:1 to receive RUX 10 mg BID and HU-placebo, or HU at the same dose/schedule and RUX-placebo. Dose adjustments were permitted for safety and efficacy. After Week 16, patients could receive open-label RUX until Week 48. The primary endpoint was the proportion of patients with a ≥50% reduction in TSS-C at Week 16; secondary endpoints included proportion of patients with a ≥50% reduction in individual TSS-C symptoms and safety. Results: Overall, 54 and 56 patients were randomized to RUX and HU, respectively; 87.0% and 89.3% remained on treatment through Week 16. At baseline, the median age (range) was 64 (36-87) in the RUX group and 66 (19-85) in the HU group; 44% and 61% were men. The majority of patients in the RUX and HU groups did not have baseline platelet counts or WBC above ELN thresholds: platelets >400 and ≤600 x 109/L (RUX 31.5%, HU 28.6%), >600 x 109/L (3.7%, 8.9%); WBC >10 and ≤15 x 109/L (16.7%, 16.1%), >15 x 109/L (11.1%, 14.3%). In the RUX and HU groups, the mean TSS-C at screening (22.4, 23.1) was higher than that at baseline (16.7, 18.0); the ratio of screening to baseline TSS-C was 1.7 and 1.6. The proportion of patients achieving a ≥50% reduction from baseline in TSS-C at Week 16 (primary endpoint) was 43.4% in the RUX group and 29.6% in the HU group (P=0.139; OR, 1.82; 95% CI, 0.82-4.04). The proportions of patients in the RUX vs HU groups achieving a ≥50% reduction in scores for itching and tiredness at Week 16 were 40.0% vs 26.4% and 54.2% vs 32.0%, respectively. Median percentage changes in individual TSS-C symptoms are shown in Table 1. Additional analyses found no correlation between individual changes in HU dose from baseline to Weeks 13-16 and percentage change in TSS-C in the HU arm (r2=0.030). Even patients maintaining the same HU dose from prior to study entry through Week 16 reported symptom improvement: 12/35 (34.3%) with no dose change, 4/12 (33.3%) with a dose increase, and 0/9 (0%) with a dose decrease had a ≥50% reduction in TSS-C. The most common nonhematologic adverse events in the RUX arm on randomized treatment were fatigue (20.4% RUX vs 10.7% HU), headache (16.7% vs 5.4%), and dizziness (13.0% vs 8.9%). The most common adverse events on HU were diarrhea (9.3% RUX vs 19.6% HU) and constipation (7.4% vs 12.5%); most events were grade 1 or 2. Grade 3 or 4 anemia or thrombocytopenia (lab values) were not reported in the RUX group; two patients in the RUX group had grade 3 or 4 neutropenia. Conclusion: In generally well controlled PV patients receiving a stable dose of HU, there was a positive trend in symptom improvement for patients switched to RUX therapy versus those continuing on HU therapy, although this was not statistically significant. The 34% response rate among patients who continued to receive a stable HU dose suggests a placebo effect that led to an underpowered study. Further analyses are required to better interpret these findings. Disclosures Off Label Use: Ruxolitinib is a JAK1/JAK2 inhibitor approved for the treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Vannucchi:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Yacoub:Alexion Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Membership on an entity's Board of Directors or advisory committees. Koschmieder:Novartis Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Byrne:Novartis Pharmaceuticals: Honoraria. Verstovsek:Incyte Corporation: Research Funding. Hunter:Incyte Corporation: Employment, Equity Ownership. Jones:Incyte Corporation: Employment, Equity Ownership. He:Incyte Corporation: Employment, Equity Ownership. Morozov:Novartis Pharmaceuticals: Employment, Equity Ownership.

Abstract Abstract 800 Background: Ruxolitinib (RUX), an oral JAK1/JAK2 inhibitor, reduced spleen volume (SV), improved myelofibrosis (MF)-associated symptoms and quality of life (QoL), and appeared to exhibit a survival advantage over placebo (PBO) in patients (pts) with MF regardless of JAK2V617F mutation status in the phase III COMFORT-I study. We describe long-term efficacy and safety of RUX from COMFORT-I, with 1 year of additional follow up beyond previously published data. Methods: Eligible pts (N=309) were randomized (1:1) to RUX or PBO. The primary analysis occurred when all pts completed 24 weeks (wks) and when half the pts completed 36 wks of treatment. All pts receiving PBO were eligible for crossover to RUX after the primary analysis; crossover before wk 24 was permitted if pts met protocol-defined criteria for worsening splenomegaly. The proportion of pts with ≥35% SV reduction at 24 wks (primary endpoint) and durability of SV response were assessed. Although symptom burden (measured daily using the modified MF Symptom Assessment Form v2.0) was only measured up to wk 24, QoL continued to be evaluated beyond wk 24 (every 24 wks) using the EORTC QoL Questionnaire-Core 30 (QLQ-C30). Overall survival (OS) was assessed according to original randomized treatment. Results: In this updated analysis, median follow-up of pts randomized to RUX was 102 wks. All pts receiving PBO completed crossover or discontinued within 3 months of the primary analysis. Of 134 pts randomized to RUX who remained on treatment after the primary data analysis, 100 continue on study. Mean SV reduction in pts randomized to RUX was 31.6% at wk 24 and has remained stable with additional follow up through wk 96 (Table). In pts who achieved a ≥35% SV reduction, response was durable, with a median response duration of 108 wks. RUX treatment was also associated with durable improvements in the Global Health Status/QoL (Table) and the 5 functional domains of the EORTC QLQ-C30. Twenty-seven (27) pts randomized to RUX and 41 pts randomized to PBO died, representing a continued OS benefit in favor of RUX (HR=0.58; 95% CI: 0.36, 0.95; P = 0.028; Fig 1) similar in magnitude to that previously reported. OS favored RUX across subgroups including starting dose as well as baseline risk status and hemoglobin (Hgb). Of 34 pts randomized to RUX who discontinued after the primary analysis, 4 discontinued for an adverse event (AE). In pts who continued on RUX, anemia and thrombocytopenia remained the most frequently reported AEs. New onset of grade 3 or 4 anemia and thrombocytopenia was reported in only 12 and 5 pts, respectively. One pt discontinued for anemia. Overall, among all pts randomized to RUX, Grade 3 and 4 anemia regardless of baseline Hgb was reported in 37.4% and 14.8% of pts, respectively. Similarly, Grade 3 and 4 thrombocytopenia was reported in 11.0% and 5.2% of pts, respectively. These rates were similar to those reported in the primary analysis. By wk 36, the proportion of pts receiving red blood cell transfusions decreased to the level seen with PBO and remained stable thereafter (Fig 2). Rates of nonhematologic AEs adjusted for increased follow-up duration remain similar to those seen at the time of the primary data analysis. No additional cases of acute myeloid leukemia (AML) in pts randomized to RUX were reported. Two pts originally randomized to PBO developed AML, 21 and 178 days after crossover to RUX. There continued to be no reports of a withdrawal syndrome after RUX discontinuation. Conclusions: RUX provides durable reductions in SV and improvements in QoL. Although all pts randomized to PBO crossed over to RUX shortly after the primary analysis, with 1 year of additional follow up, RUX continues to be associated with a survival advantage over PBO. RUX continues to be well tolerated; the AE profile with long-term treatment is consistent with that previously reported. The proportion of pts receiving transfusions decreased over time to rates similar to PBO, and there were no reports of a specific withdrawal syndrome or cytokine rebound phenomenon after RUX discontinuation. Disclosures: Verstovsek: Incyte Corporation: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Gotlib:Incyte: Consultancy, travel to congress Other. Levy:Incyte: Employment, Equity Ownership. Gupta:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; YM Biosciences: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofiå]Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Catalano:Incyte: Consultancy. Deininger:Bristol-Myers Squibb: Consultancy, Research Funding; Novartis: Consultancy; Ariad: Consultancy. Miller:Novartis: Consultancy, Research Funding, Speakers Bureau, development of educational presentations Other; Incyte: development of educational presentations, development of educational presentations Other. Talpaz:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; B.M.S.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Winton:Incyte: Consultancy, Honoraria. Arcasoy:Incyte: Research Funding. Lyons:Incyte: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Novartis: Research Funding; Telik: Research Funding. Paquette:Incyte: Consultancy. Vaddi:Incyte: Employment, Equity Ownership. Erickson-Viitanen:Incyte: Employment, Equity Ownership. Sun:Incyte Corporation: Employment, Equity Ownership. Sandor:Incyte Corporation: Employment, Equity Ownership. Kantarjian:Incyte: grant support Other.

Case Report.Aspergillusosteomyelitis is a destructive and progressive infection that has been described both in immunosuppressed and in immunocompetent hosts. We describe a case of lumbar vertebral osteomyelitis in a 61-year-old immunocompetent patient due toAspergillus nidulansthat was successfully treated with a combination of extensive surgical debridement, spinal stabilization, and a prolonged course of antifungal therapy. Imaging demonstrated findings consistent with L3 discitis. The biopsy grewAspergillusfungus and was treated with vorconizole. Imaging showed progressive destructive osteomyelitis at L3-L4. Patient underwent anterior L3 and L4 partial corpectomies, anterior interbody fusion L3-L5, and posterior T11-S2 pedicle screw and rod fixation. Antifungal treatment resulted in resolution of infection.Aspergillusmarkers remain negative. One year following definitive treatment, the patient’s back pain remains resolved.Conclusion. Definitive surgical resection of the infection, spinal stabilization, and aggressive antifungal therapy were required to eradicate the infection.

Participation refers to a state of health in which a person is able to fully engage in roles and life situations. Adults living with and beyond cancer often report persistent participation restrictions that affect their productivity and quality of life. The American Occupational Therapy Foundation convened a group of scientists from seven different disciplines in a Planning Grant Collective (PGC) to stimulate research to identify scalable ways to preserve and optimize participation among cancer survivors. Participants identified challenges, prioritized solutions, and generated novel research questions that move beyond symptom and impairment mitigation as outcomes to identify interventions that improve participation in roles and life situations. This article summarizes the PGC discussion and recommendations regarding three challenges: (a) the dynamic and multi-faceted nature of participation, (b) a need to integrate the concept of participation within the culture of oncology, and (c) identification of priority areas in which new lines of research regarding participation would be most impactful.

Abstract BACKGROUND AND IMPORTANCE Deep brain stimulation (DBS) is a well-established treatment for medically refractory Parkinson's disease (PD), essential tremor (ET), and dystonia. The field of DBS is expanding and techniques are under investigation for the treatment of several neurological disorders. A critical component of the success of these procedures depends significantly on the reliability and durability of devices implanted. Immediate feedback during surgery often gives the surgeon and patient a sense of confidence of long term success. When impedances are found to be elevated during the implantation of the DBS leads, appropriate trouble shooting measures are critical. CLINICAL PRESENTATION We present a 73-yr-old male undergoing awake subthalamic DBS with microelectrode recordings for severe PD. Once the optimal trajectory and depth were ascertained, the permanent DBS electrode was placed. High impedances were recorded. Troubleshooting procedures were performed and were all negative as to the cause of the values. Correct impedance levels of the DBS electrode was confirmed with extracranial testing, but continued high values were found again with intracranial positioning of the electrode. A postoperative computerized tomography (CT) scan confirmed intracranial air surrounding all of the contacts. The patient went on to outpatient programming with excellent clinical results. CONCLUSION The presence of pneumocephalus surrounding the DBS lead contacts at the target nucleus may have accounted for the intraoperative impedance findings. When all troubleshooting checks have not identified an explanation for the high impedances, intraoperative imaging may demonstrate pneumocephalus around the lead contacts, which should resolve and impedances return to normal values.