Abstract
Background and Purpose
Treatment with the iron chelator, deferoxamine mesylate (DFO), improves neurological recovery in animal models of Intracerebral hemorrhage (ICH). We aimed to evaluate the feasibility, safety, and tolerability of varying dose-tiers of DFO in patients with spontaneous ICH, and to determine the Maximum Tolerated Dose (MTD) to be adopted in future efficacy studies.
Methods
A multicenter, phase-I, dose-finding study using the Continual Reassessment Method. DFO was administered by an intravenous infusion for 3 consecutive days, starting within 18 hours of ICH onset. Subjects underwent repeated clinical assessments through 90 days, and CT neuroimaging pre- and post-drug administration.
Results
Twenty subjects were enrolled into 5 dose tiers, starting with 7 mg/kg/day and ending with 62 mg/kg/day as the MTD. Median age was 68 years (range: 50–90); 60% were men; and median GCS and NIHSS scores on admission were 15 (5–15) and 9 (0–39), respectively. ICH location was lobar in 40%, deep in 50%, and brainstem in 10%; intraventricular hemorrhage was present in 15%. DFO was discontinued due to adverse events in 2 subjects (10%). Six subjects (30%) experienced 12 serious adverse events (SAEs), none were drug-related. DFO infusions were associated with mild blood pressure lowering effects. Fifty percent of patients had mRS ≤2 and 39% had mRS 4–6 on day-90; 15% died.
Conclusions
Consecutive daily infusions of DFO after ICH are feasible, well-tolerated, and not associated with excessive SAEs or mortality. Our findings lay the groundwork for future studies to evaluate the efficacy of DFO in ICH.
Keywords: Deferoxamine Mesylate, Iron, ICH
INTRODUCTION
At present, there is no specific treatment for intracerebral hemorrhage (ICH) beyond supportive and aggressive medical care. The iron chelator, deferoxamine mesylate (DFO), is a potentially promising therapeutic intervention to target the secondary effects of ICH in order to limit brain injury, facilitate neuronal repair, and improve outcome.
Hemoglobin and its degradation products, particularly iron, released from the hemolysed red blood cells after ICH are implicated in neuronal injury via several mechanisms including exacerbation of excitotoxicity, autophagy, hydroxyl radical formation and oxidative stress [1–8]. Besides chelating iron, DFO has other diverse neuroprotective properties, independent of its iron-chelating properties [9]. It has anti-apoptosis, anti-oxidative stress, anti-phagocytosis, and anti-inflammatory effects [10–12]; and blocks hemoglobin-mediated accentuation of glutamate excitotoxicity [5]. Animal studies have shown that DFO reduces hemoglobin-induced neurotoxicity in vitro and in animal models of hemorrhage; and improves neurological function after experimental ICH in several species [13–15].
In order to translate these pre-clinical data, we undertook the current study to assess the tolerability and safety of DFO in patients with ICH, and to determine the maximum tolerated dose to be investigated in future studies to determine whether treatment with DFO would improve the overall outcome after ICH.
METHODS
Subjects and Overall Study Design
This was a multicenter phase-I dose-finding study using the Continual Reassessment Method (CRM) [16]. Subjects with spontaneous ICH, presenting to the emergency department within 18 hours of symptom onset, were enrolled from July 2008 to January 2010 at 4 sites: Beth Israel Deaconess Medical Center (n =6), Massachusetts General Hospital (n =5), Medical College of Wisconsin (n =5), and Hartford Hospital (n =4). The Data Coordination Unit, housed in the Division of Biostatistics and Epidemiology at the Medical University of South Carolina, served as the Statistical and Data Management Center for the study. The study was approved by the local Institutional Review Boards, and all subjects (or their legal representatives) were required to sign written informed consent prior to enrollment. Supplemental table 1 lists the inclusion and exclusion criteria.
The study was supported by the National Institute of Neurological Disorders and Stroke (NINDS), and registered with ClinicalTrials.Gov as NCT00598572. An Investigational New Drug (IND) was granted from the US Food and Drug Administration to conduct the study (IND # 77306).
Study Procedures
All patients with ICH were screened upon presentation. A pre-treatment baseline plain CT scan establishing the presence of ICH was required to confirm the diagnosis. Neurological examination included assessments of National Institute of Health Stroke Scale (NIHSS) and Glasgow Coma Scale (GCS) scores, and study-specific visual and auditory tests (whenever possible in awake patients), which included assessments for cataract, hearing loss, color blindness, and tinnitus. Consecutive eligible patients were approached for consent and underwent baseline examination (repeated NIHSS, GCS, and physical examination including vital signs) 3–6 hours later to assure neurological stability. Stable subjects received the first dose of the study drug within 45 minutes of baseline assessments and 18 hours of ICH symptom onset. All subjects were admitted to Neurological Intensive Care or Stroke units; the general care of subjects conformed to the guidelines from the Stroke Council of the American Heart Association [17]. Supplemental table 2 summarizes the timing and type of various assessments throughout the study. Subjects were monitored for safety and vital signs recorded every 30 minutes during each infusion and hourly afterwards. The subjects were contacted by phone on day-90 (±7 days) to assess modified Rankin Scale (mRS), Barthel Index (BI), and extended Glasgow outcome scale (GOS-E) scores and mortality. All adverse events (AEs) were assessed until day 7 or discharge (whichever was earlier), and SAEs until the completion of the study on day 90. Administration of DFO may result in a vin rosé discoloration of urine in patients with systemic iron overload, which raised concerns regarding the potential for unblinding in future controlled trials of DFO. Therefore, we performed urine analyses at multiple points during treatment with DFO.
Weight-adjusted intravenous infusions of DFO were administered at a rate of 7.5 mg/kg/hour and repeated daily for 3 consecutive days. The first cohort received a dose of 7 mg/kg/day, with subsequent cohorts treated at dose-tiers determined according to the Piantadosi modified CRM [16]. Regardless of subject weight or assigned dose, the maximum daily dose was restricted to 6000 mg/day, in accordance with the manufacturer’s brochure and FDA recommendations, to minimize risk of toxicity. A minimum cohort size of 3 subjects was pre-specified for each dose. The safety information guiding the transition from one dose to the next was based on the number of subjects in a cohort who experienced pre-specified dose-limiting toxicities (DLTs). In order to guard against rapid dose escalation, we pre-specified incremental increases of ≤25 mg/kg/day until a DLT was observed, at which time the CRM was implemented to determine the dose for each of the subsequent cohorts.
To assure safety, we conservatively defined DLTs as any of the following AEs occurring within 7 days of initiation of treatment with DFO or until discharge (whichever was earlier): 1) Anaphylaxis at any time point during DFO infusion; 2) Hypotension, defined as a decrease in SBP >20 mmHg or DBP >10 mmHg, or SBP <85 mmHg, confirmed by 3 consecutive readings, and requiring medical treatment at any time point during DFO infusion, that cannot be explained by other causes; 3) Worsening neurological status, defined as an increase ≥4 points on NIHSS or a decrease of ≥2 points on GCS, that cannot be explained by other causes, occurring at any time point during DFO infusion; 4) Mortality, regardless of relationship to DFO; and 5) Any AE prolonging hospital stay, resulting in emergent medical therapy, or resulting in death, regardless of relationship to DFO.
An independent Medical Safety Monitor (MSM) reviewed all SAEs and DLTs on an ongoing basis. The MSM communicated his decisions directly to the Chair of the NINDS-appointed Data and Safety Monitoring Board (DSMB). As a safety precaution, we planned to suspend enrollment if 2 of the 3 subjects in a cohort experienced DLTs in order to allow for a DSMB review of the accumulated data to make a recommendation for early termination versus resumption of the study.
Outcome Measures
The primary outcome measure was safety, defined as the occurrence of DLTs as defined above. There was no lost-to-follow up (LTFU) with regard to safety outcomes, since the CRM was based on safety assessments conducted during hospitalization through day 7 or discharge (whichever was earlier).
Since this study was envisioned as a prelude to future efficacy studies, we assessed various neurological and functional outcome scales (mRS, BI, and GOS-E) on day 90. We also explored the effects of treatment on the progression of hematoma and relative perihematoma edema (PHE) volumes on serial CT scans, primarily for safety purpose, to ensure that DFO does not aggravate hematoma or PHE growth. We used relative PHE, as opposed to the absolute PHE volume, to adjust for underlying ICH volume [18]. Computerized radiological volumetric measurements were carried out by a single investigator, blinded to the assigned dose and clinical data, as previously described [19]. The blinded investigator examined the ICH and PHE volumes in 10 randomly selected, de-identified, scans twice at an interval of several months apart. The test-retest intra-class correlation coefficients for intra-observeragreements were 1.0 for both ICH and PHE volume measurements. The concordance correlation coefficient was 0.996 (95% CI 0.990–0.999) for ICH and 0.998 (95% CI 0.993–0.999) for PHE volumes.
Statistical Analysis
The CRM was used to identify the maximum tolerated DFO dose, defined a priori as the dose associated with a 0.40 DLT probability. The maximum acceptable DLT probability of 0.40 was pre-specified based on the weighted average of all SAEs reported in placebo-treated patients who participated in recent ICH trials (FAST, CHANT, GAIN) [20–22]. Under the CRM, when the third subject in each cohort completed the 7-day or discharge period, the dose-toxicity curve was updated based on the DLTs observed in all previously enrolled subjects, and the estimated MTD obtained from the updated curve. Subjects enrolled into the following cohort were then treated at the re-estimated MTD. This reassessment process was repeated until the stopping convergence criterion was reached. The CRM algorithm was considered to have converged when the re-estimated MTD following completion of the current cohort was within 5% of the current dose. Analysis of CRM data was carried out on an ongoing basis throughout the study. The DLT data were available to the study statistician (SY), who implemented the CRM algorithm and updated the dose for subsequent cohorts.
Adverse events were assigned to a system-organ class and preferred term using the MedDRA coding dictionary. Exploratory descriptive statistics (median, range, percentages) of additional safety parameters and clinical and radiological data were computed by dose group. The effect of DFO on laboratory parameters and vital signs is summarized by the median change in the corresponding parameter and 95% confidence interval.
RESULTS
Subjects Baseline and Clinical Characteristics
A total of 20 subjects were enrolled into six cohorts during the course of the study. Two subjects (10%) withdrew consent following the treatment period; neither withdrawal was due to an AE. No other subjects were lost-to-follow up.
The first cohort (N =4) was treated at 7 mg/kg/day, the pre-specified starting dose, with subsequent cohorts treated at doses identified by the CRM algorithm as follows: 32 mg/kg (N =3), 47 mg/kg (N =3), 57 mg/kg (N =4), and 62 mg/kg (N =3). Upon completion of the fifth cohort, the updated dose-toxicity curve indicated that the next cohort should maintain the 62 mg/kg/day dose. As this met our pre-specified convergence criterion, the final estimated MTD is 62 mg/kg/day. Thereafter, following consultation with the DSMB, we enrolled 3 additional subjects at the MTD in order to collect further safety data at this dose. Table 1 summarizes the demographic, baseline, and clinical characteristics of trial subjects by assigned dose.
Table 1.
Demographic and Clinical Characteristics of Patients per Dose-Tier
| Dose | Total | |||||||
|---|---|---|---|---|---|---|---|---|
| 7 mg/kg | 32 mg/kg | 47 mg/kg | 57 mg/kg | 62 mg/kg | ||||
| N=4 | N=3 | N=3 | N=4 | N=6 | N=20 | |||
| Age (years) | Median (range) | 50 (50–69) | 66 (53–76) | 67 (54–85) | 76 (65–90) | 70 (55–80) | 68 (50–90) | |
| Sex | Male (%) | 2 | 2 | 1 | 2 | 5 | 12 (60.0) | |
| Race | White (%) | 3 | 2 | 3 | 3 | 6 | 17 (85.0) | |
| African American (%) | 1 | 1 | 0 | 1 | 0 | 3 (15.0) | ||
| Ethnicity | Hispanic or Latino (%) | 1 | 0 | 0 | 1 | 0 | 2 (10.0) | |
| Medical History | Other Stroke | 1 | 1 | 0 | 1 | 2 | 5 (25.0) | |
| Hypertension | 4 | 3 | 2 | 4 | 5 | 18 (90.0) | ||
| Hyperlipidemia | 2 | 2 | 2 | 2 | 3 | 11 (55.0) | ||
| Diabetes mellitus | 1 | 0 | 1 | 1 | 1 | 4 (20.0) | ||
| Baseline Vitals | SBP (mmHg) | Median (range) | 145 (132–168) | 130 (110–144) | 158 (157–177) | 154 (136–164) | 134 (125–146) | 143 (110–177) |
| DBP (mmHg) | Median (range) | 76 (50–88) | 67 (66–101) | 77 (66–86) | 66 (58–75) | 68 (52–75) | 69 (50–101) | |
| MAP | Median (range) | 97 (80–115) | 93 (81–111) | 104 (96–116) | 99 (84–100) | 88 (81–97) | 96 (80–116) | |
| Screening Glucose | Median (range) | 136 (110–163) | 109 (88–137) | 210 (109–379) | 140 (113–258) | 131 (100–166) | 131 (88–379) | |
| Baseline NIHSS | Median (range) | 15 (7–28) | 0 (0–1) | 8 (5–9) | 12 (1–22) | 13 (1–35) | 9 (0–35) | |
| Baseline GCS | Median (range) | 13 (7–15) | 15 (15–15) | 15 (14–15) | 13 (11–15) | 13 (5–15) | 15 (5–15) | |
| Screening CT | Hematoma Volume (ml) | Median (range) | 10 (3–40) | 2 (1–6) | 29 (3–39) | 23 (4–41) | 18 (1–45) | 12 (1–45) |
| Location | Infratentorial (%) | 1 | 0 | 0 | 0 | 1 | 2 (10.0) | |
| Supratentorial (%) | 3 | 3 | 3 | 4 | 5 | 18 (90.0) | ||
| Lobar (%) | 0 | 1 | 1 | 3 | 3 | 8 (40.0) | ||
| Deep (%) | 3 | 2 | 2 | 1 | 2 | 10 (50.0) | ||
| IVH* | Present (%) | 2 | 0 | 1 | 0 | 0 | 3 (15.0) | |
| Time from Onset to Treatment (hours) | Median (range) | 11 (8–12) | 17 (14–22)§ | 13 (13–18) | 17 (15–18) | 13 (8–18) | 14 (8–22) | |
Intraventricular hemorrhage
One subject was enrolled 22 hours after symptom onset. At the time of enrollment, symptom onset was thought to be 23:00. After enrollment, additional information became available which indicated that symptom onset was at 15:00, eight hours earlier
Safety Data
Adverse Events
The infusions of DFO were, overall, well tolerated. Seventeen subjects (85%) completed the 3-day study drug infusions. In two (10%) subjects, the infusions were prematurely discontinued due to adverse events: shoulder pain, initially thought to be infusion-related, which was later determined unrelated; and visual hallucinations, thought to be possibly study drug-related. One subject only received the first infusion, without experiencing adverse events, but subsequent infusions were not continued because his family declined further treatment.
A total of 94 AEs (12 serious (13%), 82 non-serious), were reported during the study. The12 SAEs occurred in 6 subjects (30%). Six of these 12 SAEs occurred in 3 subjects during the first 7 days of hospitalization. One subject (in the 62 mg/kg dose-tier) experienced 5 SAEs. Three subjects (15%) experienced 4 DLTs; of these 2 subjects, both treated at the 62 mg/kg dose, developed aspiration pneumonia and required intubation. These were considered DLTs, since the intubation prolonged their hospital stay. Because the rate of DLTs in this cohort (0.33) was less than our pre-specified acceptable probability of 0.40, the 62 mg/kg/day dose still met our predefined criteria for the MTD. Table 2 summarizes the occurrence of DLTs and SAEs by dose-tier.
Table 2.
Serious Adverse Events and Dose-limiting Toxicities
| Dose | Total | ||||||
|---|---|---|---|---|---|---|---|
| 7 mg/kg | 32 mg/kg | 47 mg/kg | 57 mg/kg | 62 mg/kg | |||
| N=4 | N=3 | N=3 | N=4 | N=6 | N=20 | ||
| Number of Subjects with Dose Limiting Toxicities* | Total | 1 | 0 | 0 | 0 | 2 | 3 (15.0) |
| Anaphylaxis during infusions | 0 | ||||||
| Unexplained hypotension requiring treatment during infusions | 0 | ||||||
| Unexplained worsening of neurological status during infusions | 0 | ||||||
| Mortality within 7 days of initiation | 1 | 0 | 0 | 0 | 0 | 1 (5.0) | |
| Any AE prolonging hospital stay, resulting in emergent therapy, or resulting in death within 7 days of initiation | 1 | 0 | 0 | 0 | 2 | 3 (15.0) | |
| Number of Subjects with Serious Adverse Events* | Total | 1 | 0 | 1 | 1 | 3 | 6 (30.0) |
| Neurological decompensation | 1 | 1$ | |||||
| Pulmonary embolism | 1 | ||||||
| Recurrent ICH | 1$ | 2 | |||||
| Aspiration leading to respiratory failure and intubation | 2 | ||||||
| Hypotension requiring vasopressor therapy | 1 | ||||||
| Renal failure | 1 | ||||||
Each subject may have multiple events reported.
One subject may have experienced the same SAE twice.
Three subjects (15%) died during the 90-day follow-up period; one subject (5%) died in hospital within 7 days of ICH onset, and two between 7 and 30 days after ICH onset. None of the SAEs, DLTs, or mortalities was adjudicated to be related to the study drug.
Sixteen (20%) non-serious AEs were possibly or probably related to the study drug. They were mild, self-limited, and did not require specific treatment. These included: injection site irritation (15%) and intravenous infiltration (20%), itching or rash (10%), visual hallucinations (5%), blurred vision (5%), a decrease in blood pressure (20%), and arm pain (10%). Supplemental table 3 summarizes all AEs by MedDRA body system, and dose-tier.
Vital Signs and Laboratory Studies
Administration of DFO did not result in important alterations in heart rate, respiratory rate, oxygen saturation, or temperature. Overall, the median mean BP (MAP) at baseline was 95.8 mmHg (95% CI 84,100.3) versus 93.2 mmHg (95% CI 87.6, 98.1) during the infusions. A total of 8 patients (40%) experienced a maximal drop in MAP >20% (median 29%; 95% CI 27, 39) at some point during the infusions compared to baseline values. One subject, in the 62 mg/kg dose-tier, required vasopressors; his hypotension was thought to be related to intubation and anesthesia. None of the remaining 7 subjects required any medical treatment. In the 62 mg/kg dose-tier cohorts, 4 out of 6 subjects (67%) experienced a maximal drop in MAP >20% during the infusions (median 29% –95% CI 25, 39; mean absolute change 22.4 mmHg – standard error 0.49); the median MAP at baseline was 87.7 mmHg (95% CI 80.7, 96.7) versus 87.4 mmHg (95% CI 79.5, 96.0) during the infusions. However, the BP drop was not clinically significant, did not meet our definition for a DLT, and did not require treatment, except in the subject mentioned above.
Analyses of laboratory data indicated no safety concerns. There were no differences in routine laboratory values and in the incidence of abnormalities and change from baseline in EKG parameters. Serum hemoglobin and hematological parameters, renal and hepatic functions, and electrolytes were stable over time. We observed no changes in urine output or color over the 3-day course of DFO infusions in any subject. Treatment with DFO did not result in iron deficiency or anemia. We found no relationship between DFO dose-tier and changes in serum iron studies. Supplemental table 4 summarizes laboratory values at baseline, 72 hours, and day-30.
Radiological Studies
Analysis of volumetric measurements of ICH and relative PHE volumes over time indicated no safety concerns at any of the tested dose-tiers. These data are summarized in Table 3. Overall, treatment with DFO was not associated with an increase in hematoma or PHE growth. The median change in ICH volume from baseline to after the 3rd DFO infusion was −0.05 cm3 (95% CI −0.87, 0.64). The overall median change in relative PHE volume from screening to post-3rd DFO infusion was 0.48 (95% CI 0.10, 0.76) and from screening to day-7 or discharge (whichever occurred first) was 0.87 (95% CI 0.51, 1.28).
Table 3.
Summary of Radiological and Clinical Outcome Data
| Dose | Total | |||||||
|---|---|---|---|---|---|---|---|---|
| 7 mg/kg | 32 mg/kg | 47 mg/kg | 57 mg/kg | 62 mg/kg | ||||
| N=4 | N=3 | N=3 | N=4 | N=6 | N=20 | |||
| Hematoma Volumes | Screening | Median (range) | 9.92 (3.05– 40.21) | 2.27 (0.98– 5.92) | 28.82 (3.39– 39.08) | 23.43 (3.65–40.84) | 17.69 (0.36–45.36) | 11.97 (0.36–45.36) |
| 72 hours | Median (range) | 9.08 (3.69–44.67) | 1.05 (0.93–6.10) | 31.19 (3.40–33.91) | 25.86 (2.83–49.29) | 21.95 (0.31–45.40) | 11.51 (0.31–49.29) | |
| Day 7 or discharge | Median (range) | 4.31 (3.65–4.96) | 3.11 (3.11–3.11) | 25.66 (23.11–28.22) | 19.94 (2.74–47.26) | 24.74 (9.65–44.64) | 21.44 (2.74–47.26) | |
| PHE Volumes | Screening | Median (range) | 6.89 (0.92–45.31) | 13.57 (1.43–14.8) | 33.2 (8.98–52.69) | 23.15 (8.38–86.17) | 24.38 (0–55.14) | 13.87 (0–86.17) |
| 72 hours | Median (range) | 12.94 (1.94–101.65) | 14.58 (2.16–15.29) | 47.35 (9.32–52.31) | 39.02 (9.12–86.46) | 33.21 (0–84.94) | 14.93 (0–101.65) | |
| Day 7 or discharge | Median (range) | 7.75 (2.78–12.73) | 13.96 (13.96–13.96) | 58.42 (49.18–67.65) | 26.64 (9.34–100.49) | 53.65 (13.05–99.42) | 37.91 (2.78–100.49) | |
| Relative PHE Volumes | Screening | Median (range) | 0.69 (0.3–1.13) | 2.29 (1.46–6.52) | 1.83 (0.85–2.65) | 1.82 (0.55–2.30) | 1.12 (0–1.65) | 1.21 (0–6.52) |
| 72 hours | Median (range) | 1.50 (0.53–2.28) | 2.39 (2.32–14.56) | 1.54 (1.52–2.74) | 1.86 (0.91–3.22) | 1.66 (0–1.97) | 1.77 (0–14.56) | |
| Day 7 or discharge | Median (range) | 1.66 (0.76–2.57) | 4.49 (4.49–4.49) | 2.26 (2.13–2.40) | 2.13 (1.34–3.41) | 2.10 (1.35–2.39) | 2.18 (0.76–4.49) | |
| GCS | Day 7 or discharge | Median (range) | 15 (10–15) | 15 (15–15) | 15 (15–15) | 15 (12–15) | 15 (7–15) | 15 (7–15) |
| NIHSS | Day 30 | Median (range) | 2 (2–6) | 0 (0–0) | 3 (2–4) | 3 (0–9) | 1 (0–11) | 2 (0–11) |
| mRS | Day 90 | Median (range) | 2.5 (1–6) | 0 (0–0) | 4.5 (3–6) | 4 (0–5) | 3 (0–6) | 2.5 (0–6) |
| BI | Day 90 | Median (range) | 100 (75–100) | 100 (95–100) | 80 (80–80) | 5 (0–100) | 100 (0–100) | 100 (0–100) |
| Mortality | During Study Period | 1 | 0 | 1 | 0 | 1 | 3 (15.0) | |
| During first 7 days | 1 | 0 | 0 | 0 | 0 | 1 (5.0) | ||
| After 7 days | 0 | 0 | 1 | 0 | 1 | 2 (10.0) | ||
Functional Outcome Data
We collected data on mRS, BI, and GOS-E at day 90. These data are summarized in Table 3. Two subjects (10%) withdrew consent, one after the 7-day visit (mRS =5), and one after the 30-day visit (mRS =1). Among the remaining 18 subjects, 9 subjects (50%) had mRS scores of 0–2; 2 (11%) had a score of 3; and 7 (39%) had scores of 4–6. Three subjects died prior to completing the 90-day assessments. Among the 15 survivors, 9 (60%) had a BI score ≥95; 2 (13%) had scores ≥60 to ≤80 and 4(27%) had scores of 0–50; 6 subjects achieved upper good recovery on GOS-E at day 90; 1 lower good recovery; and 8 moderate-to-severe disability.
Animal studies have shown that human-equivalent doses of DFO ≥16 mg/kg are associated with improved outcome after experimental ICH [15]. Therefore, we explored trends in functional outcome data among the 14 subjects who completed the study in the 32 mg/kg to 62 mg/kg dose-tier cohorts. Seven (50%) had mRS of 0–2 and 6 (43%) had mRS of 4–6 at day 90. The baseline characteristics for this subgroup were as follows: median age 71 years; admission ICH volume 16.5 ml; baseline NIHSS 7; baseline GCS 14.
DISCUSSION
The primary objectives of this phase-I study were to investigate the feasibility, tolerability, and safety of repeated infusions of DFO in patients with acute spontaneous ICH, and to determine its MTD to be used in future phase II and III studies. We found that repeated daily infusions of DFO for 3 consecutive days after ICH onset are feasible and well tolerated; are not associated with an increase in SAEs or mortality, when compared with placebo-treated patients in recent ICH trials [20–22]; and do not result in substantial biochemical, hematological, or radiological adverse events. DFO has been used in clinical practice for over 40 years, mostly for the treatment of acute iron intoxication and chronic iron overload in patients requiring repeated blood transfusions. The safety profile of DFO in this study is in line with previous clinical experience of DFO use in non-stroke patients [23]. In rat models of ICH, DFO doses of 100 mg/kg/day and 200 mg/kg/day were both effective in improving neurological and functional recovery [15]; based on mass constant conversion factors, the calculated human equivalent doses are approximately 16 mg/kg/day and 32 mg/kg/day. We identified 62 mg/kg/day (up to a maximum daily dose of 6000 mg/day, irrespective of body weight) as the MTD for DFO infusions.
There is growing experimental and clinical evidence linking iron-mediated toxicity to secondary neuronal injury after ICH [1–7]. Animal studies demonstrate an increase in iron-positive cells, heme oxygenase protein, and markers of DNA damage in the perihematoma area within the first day after ICH, which peak by day 3 [3, 10]. In ICH patients, serum ferritin upon admission correlates with the relative PHE on day-3 (which coincides with the timing for hemoglobin hemolysis [24]) [19], and functional outcome at 3 months [25]; and the iron content within the hematoma, estimated by MRI, correlates with the relative PHE volume [26]. There is also extensive pre-clinical evidence that the iron-chelator, DFO, confers substantial neuroprotection and reduces hemoglobin-induced neurotoxicity after ICH in different species and by different investigators [6, 10, 13–15]. These studies have shown that the benefit of DFO in ameliorating secondary neuronal injury after ICH is mediated via several diverse mechanisms and may be at least partly independent of its iron-chelating effects [5, 10–12]. Our findings that the MAP decreases by approximately 2 mmHg during DFO infusions indicates that DFO also exerts a mild BP-lowering effect, which may be of some potential benefit in ICH [27]. Therefore, DFO is a rational choice for further investigations as a potential therapeutic intervention to improve the outcome of patients with ICH.
This study represents the first translational attempt in this regard. Most attention in ICH research has been focused on targeting hematoma and its expansion, utilizing various approaches such as surgical evacuation, endoscopic aspiration with or without lysis, ultra-hemostatic therapy, or intensive blood pressure lowering. In contrast, treatment with DFO aims to target the pathophysiological mechanisms that contribute to secondary neuronal injury which continues for days after ICH onset, and if successful can provide a complementary therapy to ongoing efforts targeting hematoma and its expansion.
Treatment with DFO at all tested dose-tiers did not result in significant alterations in hematological or serum iron studies. Serum ferritin, however, showed a trend towards an increase following treatment (Supplemental Table 2). This may be related to a paradoxical increase in serum ferritin following ICH as part of an acute stress response [28]. Our study did not include a placebo arm to adequately address this possibility and to assess whether treatment with DFO in our study might have blunted an otherwise greater rise in serum ferritin. The lack of significant reduction in serum iron studies after 3-day treatment with DFO may be similarly explained, and does not necessarily imply lack of its potential efficacy in ICH. Again, the benefit of DFO may be, at least partly, independent of its iron-chelating effects [5, 10–12]. Previous animal studies have shown that DFO decreases ferritin-positive cells in the brain following ICH [14]. However, they did not examine the effects of DFO on serum ferritin levels. Future studies should examine the levels of serum ferritin and iron following experimental ICH and the effects of DFO on these measures; and carefully probe the temporal changes in these serum measures during the days following ICH in DFO- and non-DFO treated patients, ideally in a randomized, placebo-controlled, trial setting.
Animal studies show that PHE volume increases rapidly between day 1 and 3 after ICH onset, when it reaches its peak [28–29]; delayed brain edema formation is largely related to hemoglobin- and iron-mediated toxicity [2, 30]; and that treatment with DFO attenuates the development of brain edema after ICH [10, 14–15]. Human studies, however, suggest that the peak in PHE is delayed beyond 3 days [31–32]. Our radiological data regarding relative PHE volume, where it increased by 0.48 from admission to day 3 and 0.87 to day-7 or discharge, are consistent with these reports; and compare favorably with previous studies evaluating the natural progression of PHE, which showed that relative PHE volume almost doubles within the first 24 to 72 hours [18–19]. Although debatable, relative PHE might influence recovery after ICH [33]. . Animal studies have shown that DFO decreases PHE, in a dose-dependent manner [13]. We did not observe a clear dose-dependent effect on PHE progression in our study. This may be due to the small number of subjects treated at each dose cohort. Future studies will need to include larger number of subjects and non-DFO treated subjects to conclusively clarify the effect of DFO on PHE. It is, important, however, to point out that our study was focused on safety and dose finding; was not designed to assess efficacy, mechanisms of action of DFO, or surrogate measures of its biological activity; and was not powered nor blinded to properly address clinical outcomes. Therefore, the above findings are purely exploratory at this stage.
We started DFO infusions within 18 hours of ICH onset. . Recent animal studies indicate that the beneficial effects of DFO are maintained when it is administered up to 48 hours after ICH induction, and that the optimal therapeutic time window is up to 24 hours [15].
Our study utilized the modified CRM statistical design, which represents a novel approach to conducting phase-I safety and dose-finding studies in stroke. The CRM provides greater responsiveness to the occurrence of AEs, minimizes exposing additional subjects unnecessarily to doses below the MTD, and allows for determination of the MTD with a small sample size.
In conclusion, the current study provides data demonstrating the feasibility, tolerability, and safety of DFO in doses up to 62 mg/kg/day, up to a maximal daily dose of 6000 mg/day, in patients with ICH. These results support further development of DFO as a potential therapy for ICH. Development of a multicenter, phase II trial of DFO in ICH is currently underway.
Supplementary Material
Acknowledgments
We thank the NINDS-appointed Data and Safety Monitoring Board; Adnan Qureshi, MD, who served as the Independent Data Safety Monitor for the study; and all the DFO in ICH study investigators.
SOURCE OF FUNDING: The study was sponsored by the NIH/NINDS (1R01-NS 057127).
The DFO in ICH Study Group
Project Management and Data Coordination Unit - The Dept. of Biostatistics, Bioinformatics, and Epidemiology at the Medical University of South Carolina, Charleston, SC: Sharon Yeatts, PhD; Yuko Palesch, PhD;; Catherine Dillon; Bonnie Waldman; Lynn Patterson; Andre Thornhill
Clinical Sites: Beth Israel Deaconess Medical Center, Boston, MA: PI: Magdy Selim; Richard Goddeau, Jr.; Coordinators: Shunaiber Tauhid and Kathrin Lieb. Medical College of Wisconsin, Milwaukee, WI: PI: Michel Torbey; Coordinator: Erin McGuire. Massachusetts General Hospital, Boston, MA: PI: Joshua Goldstein/Jonathan Rosand; Coordinator: Alex Oleinik; University of Connecticut/Hartford Hospital, Hartford, CT: PI: Joao Gomes; Coordinator: Martha Ahlquist. Central Imaging Laboratory - BIDMC, Boston, MA: Gottfried Schlaug; Lin L. Zhu. Consultants: Guohua Xi, Lewis Morgenstern, and Steven Greenberg.
Footnotes
DISCLOSURES: The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
DISCLOSURE STATEMENTS:
All investigators received modest support from the NINDS (1R01-NS 057127); Dr. Selim received significant support as the Principal Investigator. Drs. Morgenstern and Xi received additional significant support from the NINDS (U01 NS052510).
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