Clinical Opportunities for Germline Pharmacogenetics and Management of Drug-Drug Interactions in Patients With Advanced Solid Cancers.

PURPOSE: Precision medicine approaches, including germline pharmacogenetics (PGx) and management of drug-drug interactions (DDIs), are likely to benefit patients with advanced cancer who are frequently prescribed multiple concomitant medications to treat cancer and associated conditions. Our objective was to assess the potential opportunities for PGx and DDI management within a cohort of adults with advanced cancer. METHODS: Medication data were collected from the electronic health records for 481 subjects since their first cancer diagnosis. All subjects were genotyped for variants with clinically actionable recommendations in Clinical Pharmacogenetics Implementation Consortium guidelines for 13 pharmacogenes. DDIs were defined as concomitant prescription of strong inhibitors or inducers with sensitive substrates of the same drug-metabolizing enzyme and were assessed for six major cytochrome P450 (CYP) enzymes. RESULTS: Approximately 60% of subjects were prescribed at least one medication with Clinical Pharmacogenetics Implementation Consortium recommendations, and approximately 14% of subjects had an instance for actionable PGx, defined as a prescription for a drug in a subject with an actionable genotype. The overall subject-level prevalence of DDIs and serious DDIs were 50.3% and 34.8%, respectively. Serious DDIs were most common for CYP3A, CYP2D6, and CYP2C19, occurring in 24.9%, 16.8%, and 11.7% of subjects, respectively. When assessing PGx and DDIs together, approximately 40% of subjects had at least one opportunity for a precision medicine-based intervention and approximately 98% of subjects had an actionable phenotype for at least one CYP enzyme. CONCLUSION: Our findings demonstrate numerous clinical opportunities for germline PGx and DDI management in adults with advanced cancer.

Low CD34+ Cell Doses Are Associated with Increased Cost and Worse Outcome after Tandem Autologous Stem Cell Transplantation in Patients with Relapsed or Refractory Germ Cell Tumors.

Tandem autologous stem cell transplantation (ASCT) improves long-term survival of platinum-refractory germ cell tumors (GCT) patients. Studies, predominantly in lymphoma, showed that CD34+ cell doses > 5.0 × 106/kg/single transplant led to decreased resource utilization. Because most GCT patients have received prior cisplatin-based treatment, collecting >10 × 106 CD34+ cells/kg is challenging. We analyzed the effect of CD34+ cell dose on resource utilization and outcome in 131 GCT patients, median age 29.5 years (range, 16 to 58), undergoing tandem ASCT. Of 262 individual transplants performed, 120 were performed as inpatient and 142 as planned outpatient. Overall, median CD34+ dose per transplant was 3.1 × 106/kg (range, 0.8 to 16.0), with no significant difference between inpatient and outpatient transplants. Patients were divided into quartiles based on the CD34 cell dose infused: Q1, 0.8 to 1.9 × 106/kg; Q2, 2.0 to 2.9 × 106/kg; Q3, 3.0 to 4.1 × 106/kg; and Q4, 4.2 to 16.0 × 106/kg. For all patients higher CD34+ cell doses were associated with significantly shorter times to neutrophil (P <.001) and platelet recovery (P <.001). For inpatient transplants higher CD34+ doses were significantly associated with shorter length of hospital stay (P <.001), fewer days of filgrastim (P <.001), i.v. antibiotic (P = .012) and antifungal (P = .03) usage; and fewer RBC (P = .001) and platelet units transfused (P <.001), resulting in overall lower cost of care (P < .001). Of the 142 planned outpatient transplants, 100 admissions were required for a median length of hospital stay of 7.0 days (range, 1 to 18). Although there was no significant difference in the rates of hospitalization between patients in different CD34+ cell dose quartiles, a significant trend was observed for shorter hospitalization (P = .01) and fewer RBC (P = .002) and platelet (P = .005) transfusions with higher CD34+ cell dose quartile. Patients receiving CD34+ cell doses in the lowest dose quartile (Q1) had significantly worse progression-free survival and overall survival compared with patients receiving higher CD34+ cell doses. Overall, resource utilization, including cost of care, is significantly reduced when patients receive higher CD34+ cell doses, indicating greater efforts to improve peripheral blood stem cell collection in this population are needed.