Unveiling Discrepant and Rare Dihydropyrimidine Dehydrogenase (DPYD) Results Using an In-House Genotyping Test: A Case Series.

Fluoropyrimidine chemotherapy is a primary component of many solid tumor treatment regimens, particularly those for gastrointestinal malignancies. Approximately one-third of patients receiving fluoropyrimidine-based chemotherapies experience serious adverse effects. This risk is substantially higher in patients carrying DPYD genetic variants, which cause reduced fluoropyrimidine metabolism and inactivation (ie, dihydropyridine dehydrogenase [DPD] deficiency). Despite the known relationship between DPD deficiency and severe toxicity risk, including drug-related fatalities, pretreatment DPYD testing is not standard of care in the United States. We developed an in-house DPYD genotyping test that detects 5 clinically actionable variants associated with DPD deficiency, and genotyped 827 patients receiving fluoropyrimidines, of which 49 (6%) were identified as heterozygous carriers. We highlight 3 unique cases: (1) a patient with a false-negative result from a commercial laboratory that only tested for the c.1905 + 1G>A (*2A) variant, (2) a White patient in whom the c.557A>G variant (typically observed in people of African ancestry) was detected, and (3) a patient with the rare c.1679T>G (*13) variant. Lastly, we evaluated which DPYD variants are detected by commercial laboratories offering DPYD genotyping in the United States and found 6 of 13 (46%) did not test for all 5 variants included on our panel. We estimated that 20.4% to 81.6% of DPYD heterozygous carriers identified on our panel would have had a false-negative result if tested by 1 of these 6 laboratories. The sensitivity and negative predictive value of the diagnostic tests from these laboratories ranged from 18.4% to 79.6% and 95.1% to 98.7%, respectively. These cases underscore the importance of comprehensive DPYD genotyping to accurately identify patients with DPD deficiency who may require lower fluoropyrimidine doses to mitigate severe toxicities and hospitalizations. Clinicians should be aware of test limitations and variability in variant detection by commercial laboratories, and seek assistance by pharmacogenetic experts or available resources for test selection and result interpretation.

Addressing barriers to increased adoption of DPYD genotyping at a large multisite cancer center.

PURPOSE: To describe the implementation of an in-house genotyping program to detect genetic variants linked to impaired dihydropyrimidine dehydrogenase (DPD) metabolism at a large multisite cancer center, including barriers to implementation and mechanisms to overcome barriers to facilitate test adoption. SUMMARY: Fluoropyrimidines, including fluorouracil and capecitabine, are commonly used chemotherapy agents in the treatment of solid tumors, such as gastrointestinal cancers. DPD is encoded by the DPYD gene, and individuals classified as DPYD intermediate and poor metabolizers due to certain genetic variations in DPYD can experience reduced fluoropyrimidine clearance and an increased risk of fluoropyrimidine-related adverse events. Although pharmacogenomic guidelines provide evidence-based recommendations for DPYD genotype-guided dosing, testing has not been widely adopted in the United States for numerous reasons, including limited education/awareness of clinical utility, lack of testing recommendations by oncology professional organizations, testing cost, lack of accessibility to a comprehensive in-house test and service, and prolonged test turnaround time. Based on stakeholder feedback regarding barriers to testing, we developed an in-house DPYD test and workflow to facilitate testing in multiple clinic locations at Levine Cancer Institute. Across 2 gastrointestinal oncology clinics from March 2020 through June 2022, 137 patients were genotyped, and 13 (9.5%) of those patients were heterozygous for a variant and identified as DPYD intermediate metabolizers. CONCLUSION: Implementation of DPYD genotyping at a multisite cancer center was feasible due to operationalization of workflows to overcome traditional barriers to testing and engagement from all stakeholders, including physicians, pharmacists, nurses, and laboratory personnel. Future directions to scale and sustain testing in all patients receiving a fluoropyrimidine across all Levine Cancer Institute locations include electronic medical record integration (eg, interruptive alerts), establishment of a billing infrastructure, and further refinement of workflows to improve the rate of pretreatment testing.

Impact of obesity on safety outcomes and treatment modifications with ado-trastuzumab emtansine in breast cancer patients.

INTRODUCTION: Ado-trastuzumab emtansine (T-DM1) is an antibody-drug conjugate indicated for the treatment of HER2-positive breast cancer. The 2012 American Society of Clinical Oncology guidelines on chemotherapy dosing in obesity recommend using full weight-based cytotoxic chemotherapy doses to treat obese patients with cancer. These guidelines were published prior to the advent of anticancer antibody-drug conjugates. There is a need to investigate the safety of T-DM1 in obese patients. METHODS: This retrospective chart review included adult patients with breast cancer receiving T-DM1. The primary endpoint was a composite of the incidence of T-DM1 treatment modifications secondary to an adverse event. Secondary outcomes included the incidence of dose reductions, dose delays, treatment discontinuations, and adverse events. RESULTS: A total of 119 patients with HER2-positive breast cancer who received T-DM1 therapy were included in this study: 44 obese patients and 75 non-obese patients. The composite outcome of treatment modifications due to toxicity was significantly higher in obese patients compared to non-obese patients (45% vs 25%, p = 0.024). Treatment delays were significantly higher in obese patients (36% vs 16%, p = 0.011). All-grade adverse events with a higher incidence in obese patients included left ventricular ejection fraction decrease (11% vs 5%), bilirubin increase (32% vs 12%), thrombocytopenia (61% vs 55%), and peripheral neuropathy (34% vs 27%). CONCLUSIONS: This study suggests obese patients receiving T-DM1 may require more treatment modifications secondary to adverse events compared to non-obese patients. Larger studies are needed to determine if obese patients are at higher risk for specific T-DM1-induced adverse events.

Retrospective Analysis of Clinical Outcomes Associated With the Use of Pegfilgrastim On-body Injector in Patients Receiving Chemotherapy Requiring Granulocyte Colony-Stimulating Factor Support.

Objectives: Pegfilgrastim is a granulocyte colony-stimulating factor (G-CSF) used as primary prophylaxis in patients receiving myelosuppressive chemotherapy regimens that have greater than 20% risk of developing febrile neutropenia (FN). Historically, pegfilgrastim has been administered 24 to 72 hours after chemotherapy, necessitating a return to clinic to receive the provider-administered injection. An alternative option is the pegfilgrastim on-body injector (OBI). With the OBI device, patients have their pegfilgrastim administered 27 hours after receiving chemotherapy while remaining at home, avoiding an additional clinic appointment. Concerns with pegfilgrastim OBI include lack of experience with the device in both the patient and provider, device-related failures, and the success of delivery. This study evaluates pegfilgrastim OBI failure rates through associated patient outcomes among cancer patients receiving chemotherapy requiring G-CSF. Methods: A retrospective electronic chart review was conducted of adult patients with cancer who received chemotherapy and pegfilgrastim OBI from July 1, 2016, to July 31, 2018. The primary objective of this study was the incidence of FN in patients receiving pegfilgrastim OBI. Results: There were no reported cases of hospitalization due to FN in patients who received pegfilgrastim OBI. Dose delays and dosage modifications were not observed in our review. The OBI device failure rate was found to be low (1.92%). Conclusion: The low device failure rate from this study suggests that the OBI is a viable option for administration of pegfilgrastim in patients receiving chemotherapy requiring G-CSF.

Risk of hepatotoxicity with trastuzumab emtansine in breast cancer patients: a systematic review and meta-analysis.

BACKGROUND: Trastuzumab emtansine (T-DM1) is an anti-HER2 antibody-drug conjugate indicated for the treatment of HER2-positive breast cancer. One of the most severe adverse events reported with T-DM1 is hepatotoxicity. The objective of our meta-analysis is to investigate the risk of hepatic adverse events in patients with breast cancer receiving T-DM1 compared with controls. METHODS: We conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing T-DM1 with a control treatment in patients with HER2-positive breast cancer. Phase II/III RCTs with available event number or event rate of hepatic toxicity with an assessable sample size were included. Relative risk (RR) and corresponding 95% confidence intervals (CI) for all grade and high-grade (grade 3/4) aspartate aminotransferase (AST) and alanine aminotransferase (ALT) elevations were calculated. RESULTS: Seven RCTs were deemed eligible and were included in the meta-analysis. The RR for all-grade AST and ALT elevations were 3.24 (95% CI 2.16-4.86; p < 0.00001) and 2.90 (95% CI 1.98-4.23; p < 0.00001), respectively. The RR for high-grade AST and ALT elevations were 2.73 (95% CI 1.07-6.93; p = 0.03) and 2.17 (95% CI 1.34-3.50; p = 0.002), respectively. CONCLUSIONS: Our meta-analysis demonstrates that T-DM1-based therapy is associated with an increased risk of AST and ALT elevations.

Mogamulizumab: An Anti-CC Chemokine Receptor 4 Antibody for T-Cell Lymphomas.

Objective: To review the pharmacology, pharmacokinetics, efficacy, safety, dosing, and administration of mogamulizumab for the treatment of T-cell lymphomas. Data Sources: A literature search of PubMed (1966 to September 2019) was conducted using the keywords mogamulizumab, KW-0761, and lymphoma. Data were also obtained from package inserts and meeting abstracts. Study Selection and Data Extraction: All relevant published articles, package inserts, and unpublished meeting abstracts on mogamulizumab for the treatment of T-cell lymphomas were reviewed. Data Synthesis: Mogamulizumab is an anti-CC chemokine receptor 4 (CCR4) monoclonal antibody that has demonstrated activity in various T-cell lymphomas. It was approved by the US Food and Drug Administration (FDA) for the treatment of adult patients with relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS) who have been treated with at least 1 prior line of therapy. Mogamulizumab demonstrated significant improvement in progression-free survival compared with vorinostat in patients with relapsed or refractory MF or SS. Serious adverse events associated with mogamulizumab include infusion-related reactions, cutaneous drug eruption, and autoimmune complications. Mogamulizumab administration in the preallogeneic hematopoietic stem cell transplant setting can increase the risk for severe posttransplant graft-versus-host disease. Relevance to Patient Care and Clinical Practice: Mogamulizumab is a first-in-class CCR4 inhibitor, providing a new option in the treatment of relapsed or refractory cutaneous T-cell lymphomas. Although not currently FDA approved for this indication, mogamulizumab may have some utility for the treatment of relapsed adult T-cell leukemia/lymphoma. Conclusion: The recent approval of mogamulizumab represents an important addition to the armamentarium of pharmacotherapies for T-cell lymphomas.

Ibrutinib for the treatment of Bing-Neel syndrome, a complication of Waldenström macroglobulinemia: Patient case report.

Bing-Neel syndrome is a rare complication of Waldenström macroglobulinemia, characterized by infiltration of lymphoplasmacytic cells to the central nervous system. Multiple treatment modalities exist including purine analogs, bendamustine, high-dose methotrexate, or high-dose cytarabine. Of interest, ibrutinib, a Bruton tyrosine kinase inhibitor has also displayed efficacy in Bing-Neel syndrome. Current literature is limited for the treatment of Bing-Neel syndrome considering its rarity, and while ibrutinib is indicated for the treatment of Waldenström macroglobulinemia, it is utilized off-label for treatment of Bing-Neel syndrome. Additionally, debate exists regarding the recommended dosing strategy for ibrutinib for this indication with disease remission demonstrated at 560 mg and 420 mg. We present a case report that provides additional evidence for this debate with a patient who received 560 mg of ibrutinib initially and maintained disease control despite a dose reduction to 420 mg for tolerability. Ultimately, more data are needed to develop standardized Bing-Neel syndrome treatment strategies with specific consideration to the use of ibrutinib in this condition.

Pancreatic cancer survival in elderly patients treated with chemotherapy.

OBJECTIVES: Pancreatic cancer is a lethal disease mostly affecting elderly people. Clinical trials on treatment contain disproportionately fewer elderly patients compared with everyday practice. This retrospective study evaluates differences in the rates of chemotherapy delivered and associated survival in different age groups. METHODS: Data were collected from the Cancer Information Resource Files on patients diagnosed with pancreatic cancer from 1993 to 2008. Patients were divided into 3 age groups, namely, A with younger than 50 years, B with 50 to 70 years old, and C with older than 70 years. RESULTS: Complete data were available on 16,694 patients. Forty-four percent were in group C.Chemotherapy was given to 38% of patients in group C versus 69% of patients in group A. A multivariate analysis revealed a similar chemotherapy benefit in all groups, as follows: group C (hazard ratio [HR], 0.51), group A (HR, 0.74), and group B (HR, 0.55). CONCLUSIONS: We found that elderly patients with pancreatic cancer receive treatment less frequently compared with younger patients. However, elderly patients receiving chemotherapy derive similar benefits. Randomized clinical trials are needed to evaluate pancreatic cancer treatment in the elderly patients, particularly given the increasing occurrence of pancreatic cancer in later life.

Biological contamination of insulin pens in a hospital setting.

PURPOSE: Biological contamination of insulin pens in a hospital setting was studied. METHODS: This prospective study, conducted at two hospitals within a multihospital system, examined 125 insulin pens that had been returned to the inpatient pharmacies after patient discharge and were refrigerated for up to 48 hours before laboratory testing. Insulin was removed from the 125 pens and examined microscopically for the presence of nucleated cells and red blood cells (RBCs). Positive samples were examined by a pathologist to determine the cell types present. An immunochromatographic assay was used to determine the presence of free hemoglobin in the insulin. The 10 control samples were negative on microscopic examination. RESULTS: Out of 125 insulin pens, 7 (5.6%) tested positive for cells or hemoglobin. Microscopic examination revealed six positive samples containing a total of nine cells, including macrophages, squamous cells, and an RBC. The sample containing the RBC was not the same sample that tested positive for hemoglobin. Based on findings of intact cells and hemoglobin in insulin pens after administration, the potential exists for transmission of infectious agents from patient to patient if a single pen cartridge is used to administer insulin to multiple patients, even if a new needle is used for each individual. CONCLUSION: Examination of 125 insulin pens used in hospitals revealed hemoglobin in 1 pen and at least one cell in another 6 pens. The nine detected cells consisted of four squamous epithelial cells, four macrophages, and one RBC.