Redman, Mary W.

Abstract Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14–labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.

7510 Background: We previously demonstrated that PFS may be a candidate surrogate endpoint for OS in ES-SCLC using data from 3 randomized trials (Foster, Cancer 2011). Here, we sought to formally assess the patient- and trial-level surrogacy of PFS using data from 9 additional randomized phase II and III trials conducted by the NCI-funded cancer cooperative groups since 1986. Methods: Individual patient data from all 12 trials (3178 patients: 9 phase III and 3 phase II) were pooled. OS was the primary endpoint in all phase III trials; 3 phase III and 1 phase II trial were positive per protocol. Patient-level surrogacy (Kendall’s tau) was assessed using the Clayton copula bivariate survival model. Trial-level surrogacy was assessed via association of the log hazard ratios on OS and PFS across trials, including: weighted (by trial size) least squares regression of Cox model effects (R² WLS) and weighted (by trial size) correlation of the copula effects (R² Copula). One trial had 4 treatment arms thus 14 total two-arm comparisons were made. Results: With a median follow-up of 41.8 months in the 106 patients still alive, the median OS and PFS across trials were 9.7 months (95% CI: 9.5, 9.9) and 5.7 months (95% CI: 5.5, 5.8), respectively. There were 3120 PFS events in total (2564 disease progressions and 556 deaths without progression). The median time from progression to death was 4.1 months (95% CI: 3.9, 4.3). PFS showed modest association with OS at the patient-level (tau= 0.56) and at the trial-level (R² WLS = 0.58; R² Copula (standard error) = 0.55 (0.29)). The 95% CIs for the predicted HR for OS given observed HR on PFS under a weighted leave-one-out prediction always included the observed HR for OS; however such intervals were wide, suggesting uncertainty on the practical use of PFS as a surrogate for OS in this setting. Conclusions: PFS failed to demonstrate surrogacy for OS in ES-SCLC based on this large pooled analysis. Given that the difference in the median PFS and OS is less than 6 months, we recommend using OS as the primary endpoint in phase III trials of previously untreated ES-SCLC.

Purpose Irinotecan plus cisplatin (IP) improved survival over etoposide plus cisplatin (EP) in Japanese patients with extensive-stage small-cell lung cancer (E-SCLC). To confirm those results and discern the potential role of population-related pharmacogenomics (PG) in outcomes, we conducted a large randomized trial of identical design to the Japanese trial in North American patients with E-SCLC. Patients and Methods Patients were randomly assigned to IP (irinotecan 60 mg/m2 on days 1, 8, and 15; cisplatin 60 mg/m2 day 1, every 4 weeks) or EP (etoposide 100 mg/m2 on days 1 through 3; cisplatin 80 mg/m2 day 1, every 3 weeks). Blood specimens for genomic DNA analysis were collected before random assignment in 169 patients. Results Of 671 patients, 651 were eligible (324 and 327 patients in the IP and EP arms, respectively). Response rates with IP and EP were 60% and 57%, respectively (P = .56). Median progression-free survival for IP and EP was 5.8 and 5.2 months, respectively (P = .07). Median overall survival for IP and EP was 9.9 and 9.1 months, respectively (P = .71). Severe diarrhea was more common with IP (19% v 3%); severe neutropenia and thrombocytopenia were higher with EP versus IP (68% v 33% and 15% v 4%, respectively). PG analysis showed that ABCB1 (C3435T)T/T (membrane transport) was associated with IP-related diarrhea; UGT1A1 (G-3156A)A/A (drug metabolism) was associated with IP-related neutropenia. Conclusion This large North American trial failed to confirm the previously reported survival benefit observed with IP in Japanese patients. Both regimens produced comparable efficacy, with less hematologic and greater gastrointestinal toxicity with IP. These results emphasize the potential importance of PG in interpreting trials of cancer therapy.