Lessons Learned Using Real-World Data to Emulate Randomized Trials: A Case Study of Treatment Effectiveness for Newly Diagnosed Immune Thrombocytopenia

Regulatory agencies are increasingly considering real-world evidence (RWE) to support label expansions of approved medicines. We conducted a comparative effectiveness study to emulate a proposed randomized trial of romiplostim vs. standard-of-care (SOC) therapy among patients with recently diagnosed (≤12 months) immune thrombocytopenia (ITP), that could support expansion of the romiplostim label. We discuss challenges that we encountered and solutions that were developed to address those challenges. Study size was a primary concern, particularly for romiplostim initiators, given the rarity of ITP and the stringent trial eligibility criteria. For this reason, we leveraged multiple data sources (Nordic Country Patient Registry for Romiplostim; chart review study of romiplostim initiators in Europe; Flatiron Health EMR linked with MarketScan claims). Additionally, unlike the strictly controlled clinical trial setting, platelet counts were not measured at regular intervals in the observational data sources, and therefore the end point of durable platelet response often used in trials could not be reliably measured. Instead, the median platelet count was chosen as the primary end point. Ultimately, while we observed a slightly higher median platelet count in the romiplostim group vs. SOC, precision was limited because of small study size (median difference was 11 × 10⁹ /L (95% CI: -59, 81)). We underscore the importance of conducting comprehensive feasibility assessments to identify fit-for-purpose data sources with sufficient sample size, data elements, and follow-up. Beyond technical challenges, we also discuss approaches to increase the credibility of RWE, including systematic incorporation of clinical expertise into study design decisions, and separation between decision makers and the data.

Treatment Patterns Among Adults with Primary Immune Thrombocytopenia Diagnosed in Hematology Clinics in the United States

PURPOSE

Patients with immune thrombocytopenia (ITP) have low platelet counts and an increased risk of bleeding. We described treatment patterns and clinical outcomes in routine practice in the United States (US).

PATIENTS AND METHODS

Using electronic health record data from hematology/oncology clinics linked to administrative claims in the US, we studied 447 adults newly diagnosed with primary ITP from 2011 to 2016. Patients with a secondary cause of thrombocytopenia were excluded. The incidence of ITP treatment initiation, bleeding events, and rescue therapy use were estimated using competing risk models.

RESULTS

At 1-year post-ITP diagnosis, 50% of patients were prescribed an oral corticosteroid, with the majority being prescribed immediately following diagnosis. Of the more common second-line options, rituximab use was the most frequent (1-year cumulative incidence: 16% [95% confidence interval: 12, 19]), followed by romiplostim (9% [7, 12] and eltrombopag (5% [3, 8]). Use of these drugs was similar at 2 years post-diagnosis. At 6 months post-ITP treatment initiation, the cumulative incidence of bleeding was similar among eltrombopag and romiplostim initiators (17% [6, 33] and 19% [9, 31], respectively) and was slightly lower in rituximab users (12% [6, 20]). However, during this same timeframe, rituximab users had a higher incidence of rescue therapy use (48% [36, 58] versus 29% [14, 46] in eltrombopag and 26% [14, 39] in romiplostim users). Although splenectomy was rare, at 6 months post-surgery nearly 20% had experienced a bleed and nearly 20% had required rescue.

CONCLUSION

This study describes the health trajectory of adults with ITP who are managed in hematology clinics in the US and could inform the design of non-interventional studies of comparative effectiveness among treatments.

Safety and efficacy of romiplostim in splenectomized and nonsplenectomized patients with primary immune thrombocytopenia

Primary immune thrombocytopenia is an autoimmune disorder characterized by increased platelet destruction and insufficient platelet production without another identified underlying disorder. Splenectomy may alter responsiveness to treatment and/or increase the risk of thrombosis, infection, and pulmonary hypertension. The analysis herein evaluated the safety and efficacy of the thrombopoietin receptor agonist romiplostim in splenectomized and nonsplenectomized adults with primary immune thrombocytopenia. Data were pooled across 13 completed clinical studies in adults with immune thrombocytopenia from 2002-2014. Adverse event rates were adjusted for time of exposure. Results were considered different when 95% confidence intervals were non-overlapping. Safety was analyzed for 1111 patients (395 splenectomized; 716 nonsplenectomized) who received romiplostim or control (placebo or standard of care). At baseline, splenectomized patients had a longer median duration of immune thrombocytopenia and a lower median platelet count, as well as a higher proportion with >3 prior immune thrombocytopenia treatments versus nonsplenectomized patients. In each treatment group, splenectomized patients used rescue medications more often than nonsplenectomized patients. Platelet response rates (≥50×10⁹/L) for romiplostim were 82% (310/376) for splenectomized and 91% (592/648) for nonsplenectomized patients (P<0.001 by Cochran-Mantel-Haenszel test). Platelet responses were stable over time in both subgroups. Exposure-adjusted adverse event rates were higher for control versus romiplostim for both splenectomized (1857 versus 1226 per 100 patient-years) and nonsplenectomized patients (1052 versus 852 per 100 patient-years). In conclusion, responses to romiplostim were seen in both splenectomized and nonsplenectomized patients, and romiplostim was not associated with an increase in the risk of adverse events in splenectomized patients. clinicaltrials.gov Identifier: 00111475(A)(B), 00117143, 00305435, 01143038, 00102323, 00102336, 00415532, 00603642, 00508820, 00907478, 00116688, and 00440037.

Efficacy and safety of the thrombopoietin receptor agonist romiplostim in patients aged ≥ 65 years with immune thrombocytopenia

Thrombopoietin receptor agonists increase platelet counts and reduce bleeding risk in patients with immune thrombocytopenia (ITP). Studies have reported that these agents may represent a risk factor for thromboembolic events, especially in the elderly, who are at increased risk for such complications relative to younger patients. In this retrospective analysis, efficacy and safety data for romiplostim in patients with ITP aged ≥65 years versus those aged <65 years are described. Data from 3 studies (N = 159; 24.5% ≥ 65 years of age) were analyzed for efficacy. Data from 13 studies (N = 1037; 28.4% ≥ 65 years of age) were analyzed for adverse events (AEs). Relative risk (RR) ratios with 95% CIs were calculated for duration-adjusted incidences of AEs for romiplostim versus placebo/standard of care (SOC) in patients ≥ 65 and <65 years. Slightly higher platelet response rates were seen among romiplostim-treated patients ≥ 65 versus <65 years. In the safety analyses, 65 (6.3%) received placebo/SOC, 69 (6.7%) received placebo/SOC and then romiplostim, and 903 (87.1%) received romiplostim only. Duration-adjusted AE rates were similar for romiplostim versus placebo/SOC in older and younger patients. The risks for grade ≥ 3 bleeding (RR 1.92; 95% CI, 0.47-7.95) and thromboembolic events (RR 3.85; 95% CI, 0.53-27.96) were numerically but not significantly higher for romiplostim versus placebo/SOC in patients ≥ 65 years. Romiplostim is effective and, with the exception of nonsignificant trends showing increased risks of grade ≥ 3 bleeding and thromboembolic events (a trend observed in other studies), generally well tolerated in older patients with ITP.

Integrated analysis of long-term safety in patients with chronic immune thrombocytopaenia (ITP) treated with the thrombopoietin (TPO) receptor agonist romiplostim

A safety analysis of pooled data from clinical studies of romiplostim, a thrombopoietin (TPO) receptor agonist, in which patients with immune thrombocytopaenia (ITP) received romiplostim, placebo, or medical standard of care (SOC) Rodeghiero et al. (Eur J Haematol 91:423-436, 2013), has been updated. Included are data from 14 trials spanning 2002-2011; placebo- and SOC-arm data are pooled. Most patients (n = 1059) were female (61 %) and Caucasian (85 %); 38 % had undergone splenectomy; 23 were children. Mean (SD) baseline platelet count was 20.6 (16.5) × 10(9)/L. Mean (SD) weekly dose of romiplostim was 4.2 (2.8) µg/kg; total exposure was 1520 patient-years. Overall, 921 patients received romiplostim only, 65 received placebo/SOC only, and 73 received placebo/SOC followed by romiplostim. Rates of haemorrhage (romiplostim, 205/100 patient-years; placebo/SOC, 263/100), thrombosis (both, 5.5/100 patient-years), haematological malignancy/myelodysplastic syndrome (romiplostim, 0.5/100 patient-years; placebo/SOC, 2.7/100), and non-haematological tumours (romiplostim, 2.2/100 patient-years; placebo/SOC, 3.6/100) were comparable among groups. Bone marrow reticulin was reported in 17 patients and collagen in one patient receiving romiplostim; one patient receiving placebo/SOC had reticulin reported. Three patients developed neutralizing antibodies to romiplostim, but not to endogenous TPO. This integrated analysis of the safety profile of romiplostim in patients with ITP is consistent with previously reported studies; no new safety concerns emerged.

Bleeding and mortality outcomes in ITP clinical trials: a review of thrombopoietin mimetics data

Patients with ITP may have severe thrombocytopenia, putting them at risk for serious bleeding. ITP trials of new treatments must allow use of standard-of-care therapies to prevent serious bleeding. Thrombopoietin mimetic trials used platelet counts and rescue/concomitant medication use as endpoints. These trials were of insufficient size and duration to measure mortality or serious bleeding, which are infrequent with appropriate treatment. A recent Cochrane review criticized the thrombopoietin mimetic registrational trials for inadequately assessing bleeding and survival. We discuss how these endpoints are difficult to measure in clinical trials designed to improve platelet counts and minimize bleeding, in accordance with ethical trial design.

Effect of religious observance on infants' sleep position in the Jewish population

OBJECTIVES

To describe the effect of the level of religiousness on infants' sleep position in the Jewish population.

METHODS

A longitudinal telephone survey of randomly selected 608 2-month-old Jewish infants repeated at 4 and 6 months. Results were analyzed versus the four levels of Jewish religion observance.

RESULTS

A significant correlation was found between the level of religious practice and sleep position (P < or = 0.002). 56.8% (50/88) of ultra-orthodox parents put their babies to sleep in the non-prone position, compared with 79% (411/520) in the other three groups (P < 0.001). Non-prone sleeping decreased when infants grew. Higher parity correlated with the level of religiousness and with prone sleeping in religious families (OR = 1.15, 95% CI 1.00-1.33, P < 0.001).

CONCLUSIONS

Jews and especially the ultra-orthodox families comply significantly less with recommendations to avoid prone sleeping. Specific measures may be required in this population that rely more on personal experience and belief than on health care provider advice.

Recurrent urinary tract infections in postmenopausal women

To evaluate factors associated with recurrent urinary tract infection (UTI) in postmenopausal women, we conducted a case-control study comparing 149 postmenopausal women referred to an infectious diseases outpatient clinic who had a history of recurrent UTI (case patients) with 53 age-matched women without a history of UTI (control patients). Each woman completed a questionnaire providing demographic data, history and clinical characteristics of prior infections, and information regarding risk factors for UTI. In addition, each patient underwent a gynecologic evaluation, renal ultrasound and urine flow studies, and blood group and secretor status testing. Three urologic factors-namely, incontinence (41% of case patients vs. 9.0% of control patients; P<.001), presence of a cystocele (19% vs. 0%; P<.001), and postvoiding residual urine (28% vs. 2.0%; P=.00008)-were all strongly associated with recurrent UTI. Multivariate analysis showed that urinary incontinence (odds ratio [OR], 5.79; 95% confidence interval [CI], 2.05-16.42; P=.0009), a history of UTI before menopause (OR, 4.85; 95% CI, 1.7-13.84; P=. 003), and nonsecretor status (OR, 2.9; 95% CI, 1.28-6.25; P=.005) were most strongly associated with recurrent UTI in postmenopausal women. Prospective studies are needed to confirm these observations and to develop approaches for prevention.

Walk-through surveys for child labor

Child labor is increasing in both developing and developed countries. Walk-through surveys were used to identify children, aged 8-15 years, working in six sites in Tel Aviv and Jerusalem, the largest cities in Israel. Of the 45 children who were interviewed, 20 were Jewish Israeli born, 19 were recent Jewish immigrants from the former Soviet Union, and six were Arabs from Judea, Samaria, and Gaza. The majority of children were either too young for employment, according to the Israeli Child Labor Laws, and/or receiving less than the legal minimum wage. Many were performing physical labor that might be expected to interfere with normal growth and development. Many of the children had visible signs of impaired physical health. Some were subjected to physical and/or verbal abuse. Walk-through surveys are recommended as a tool for routine use for surveillance of hazardous working conditions, case-finding, and evaluating the efficacy of preventive measures. The World Health Organization recommendations are emphasized to eliminate hazardous working conditions and to provide on-the-job health and social services to working children.

Whole bone marrow irradiation for the treatment of multiple myeloma

Nine patients with multiple myeloma were treated with whole bone marrow irradiation. Six had heavily pretreated disease refractory to chemotherapy. Three had stable disease lightly pretreated by chemotherapy. A modification of the "three and two" total nodal radiation technique was employed. Although varying and often severe treatment related cytopenia occurred, infectious complications, clinical bleeding, and nonhematalogic complications were minimal. Five of nine patients showed a decrease in monoclonal protein components, and one showed an increase during treatment. These preliminary results indicate that a reduction of tumor cell burden may occur in patients following whole bone marrow irradiation and that the technique is feasible. Whole bone marrow irradiation combined with chemotherapy represents a new conceptual therapeutic approach for multiple myeloma.

Sequence of fibrinogen proteolysis and platelet release after intrauterine infusion of hypertonic saline

Plasma fibrinopeptide B (Bbeta1-14 or FPB) immunoreactivity was studied by radioimmunoassay in patients who received intrauterine infusion of hypertonic saline to terminate pregnancy. FPB immunoreactivity increased with thrombin treatment (TIFPB) suggesting the presence of a larger FPB-containing peptide, since purified FPB is not altered by thrombin, whereas thrombin increases the immunoreactivity of Bbeta1-42 (which includes FPB) 10-fold. TIFPB immunoreactivity in plasma, drawn 4 h after hypertonic saline infusion eluted from Sephadex G-50 similarly to isolated Bbeta1-42. Streptokinase, incubated with normal plasma progressively generated TIFPB immunoreactivity, which showed a major component which eluted from Sephadex G-50 similarly to Bbeta1-42. Streptokinase generated TIFPB much more rapidly in reptilase-treated plasma that contains fibrin I, (which still includes FPB), indicating that fibrin I is preferred over fibrinogen as a substrate for plasmin cleavage of arginine (Bbeta42)-alanine (Bbeta43). Serial studies were then made in 10 patients receiving intrauterine hypertonic saline. Fibrinopeptide A (FPA) levels rose immediately, reached a peak between 1 and 2 h, were declining at 4 h, and were normal at 24 and 48 h. TIFPB levels rose slightly in the 1st h, reached a peak at 4 h, and had returned to base-line values at 24 h. Serum fibrinogen degradation product levels were unchanged at 1 h, reached their highest level at 4 h, and were still markedly elevated at 24 and 48 h. Fibrinogen levels dropped slightly being lowest at 4 and 24 h. Platelet counts declined in parallel with the fibrinogen levels over the first 4 h, but continued to decrease through 48 h. Beta thromboglobulin (betaTG) levels generally paralleled FPA levels whereas platelet factor 4 (PF4) levels showed only slight changes. The data indicate that immediately after intrauterine hypertonic saline infusion thrombin is formed that cleaves FPA from fibrinogen to produce fibrin I and releases betaTG and PF4 from platelets. Later plasmin cleaves Bbeta1-42 from fibrin I to produce fragment X, which is further degraded to form serum fibrinogen degradation products. This sequence of proteolysis indicates that plasmin action on fibrin I serves as a mechanism that regulates fibrin II formation by removing the Bbeta chain cleavage site, which is required for thrombin action in converting fibrin I to fibrin II.

Anticoagulation and high dose liver radiation: a preliminary report

Two groups of patients were observed for evidence of acute radiation hepatitis during "high dose" radiation to the liver. The first group of 18 patients with metastatic liver disease received an average of 4,050 rad to the whole liver. Half received anticoagulation with warfarin. One patient on anticoagulation developed evidence of acute radiation hepatitis while 2 patients did so without anticoagulation. Eleven patients with Hodgkin's disease received 4,000 rad to the left lobe of the liver during extended field radiation. Four of these 11 patients were anticoagulated to therapeutic range. Only one of the fully anticoagulated patients showed changes on liver scan consistent with radiation hepatitis whereas three did so without anticoagulation. No serious sequelae from anticoagulation occurred in either group. These preliminary data suggest that anticoagulation may be safely administered with high dose hepatic radiation and that further trials with anticoagulation are warranted.

Fibrinogen Bβ Chain Proteolysis by Thrombin and Plasmin - A Regulatory Mechanism in Hemostasis and Thrombosis

Thrombin cleaves fibrinogen in two steps producing fibrin I and fibrinopeptide A(FPA) and then fibrin II and fibrinopeptide B(FPB). Plasmin cleaves the Aα chain and the N-terminal Bβ chain to form fragment X. Radioiimminoassay of plasma FPA reflects fibrin I formation. A modified FPB assay detects plasm in-produced Bβ1-42, reflecting fragment X formation. Sequential changes have been studied in saline abortion and in venous thrombosis. Following intra-uterine infusion of hypertonic saline to interrupt pregnancy, FPA levels rose immediately from 1 to 18 pmol/ml in 60 minutes, and after 2 hours began to slowly decline to the baseline level. Bβ1-42 levels rose rapidly after the first hour to reach 67 pmol/ml at 4 hours. Thus fibrin I was formed and then fragment X. In post-surgical patients FPA levels rose and exceeded Bβ1-42 levels for several days preceding thrombosis indicated by 125I-fibrinogen scanning and confirmed by venography. These results suggest that following injury thrombin forms fibrin I. Each fibrin I molecule is then either cleaved by thrombin to form fibrin II or by plasmin to form fragment X. The balance between thrombin and plasmin proteolysis of the N-terminal Bβ chain may be critical. Normally sufficient fibrin II formation occurs for effective hemostasis. Thrombosis occurs with excessive thrombin action and fibrin II formation. Slow thrombin formation as in hemophilia results in preferential formation of fragment X and ineffective hemostasis.

Anticoagulation and high dose liver radiation: a preliminary report

Two groups of patients were observed for evidence of acute radiation hepatitis during "high dose" radiation to the liver. The first group of 18 patients with metastatic liver disease received an average of 4,050 rad to the whole liver. Half received anticoagulation with warfarin. One patient on anticoagulation developed evidence of acute radiation hepatitis while 2 patients did so without anticoagulation. Eleven patients with Hodgkin's disease received 4,000 rad to the left lobe of the liver during extended field radiation. Four of these 11 patients were anticoagulated to therapeutic range. Only one of the fully anticoagulated patients showed changes on liver scan consistent with radiation hepatitis whereas three did so without anticoagulation. No serious sequelae from anticoagulation occurred in either group. These preliminary data suggest that anticoagulation may be safely administered with high dose hepatic radiation and that further trials with anticoagulation are warranted.