Clinical significance of coadministration of moderate to strong CYP enzyme inhibitors with doxorubicin in breast cancer patients receiving AC chemotherapy.

INTRODUCTION: Cytochrome P450 (CYP) enzyme inhibitors may increase the toxicity of many chemotherapies. Medication databases classify doxorubicin coadministration with CYP2D6 or CYP3A4 inhibitors as either a major interaction or contraindication. This study assessed the incidence of toxicity secondary to doxorubicin given with or without CYP enzyme inhibitors in breast cancer patients receiving doxorubicin and cyclophosphamide. METHODS: This retrospective study included female breast cancer patients treated with doxorubicin and cyclophosphamide (AC). Patients were divided into three arms: no moderate or strong CYP inhibitor interactions, moderate or strong CYP2D6 inhibitor interactions, or moderate or strong CYP3A4 inhibitor interactions. Primary outcomes included incidence of doxorubicin-associated toxicity, unplanned medical visits, chemotherapy treatment delays, and doxorubicin dose reductions. The secondary endpoint was time to toxicity. RESULTS: There were 171 patients included (n = 20 patients in the CYP2D6 inhibitor group and n = 15 in the CYP3A4 inhibitor group). Neither CYP inhibitor group showed a difference in incidence of hepatotoxicity, cardiotoxicity, myelotoxicity, moderate/severe nausea, or treatment delays. Compared to the no CYP inhibitor group, the CYP2D6 inhibitor group experienced a higher incidence of unplanned medical visits (45% vs. 19.4%; p = 0.023) and more frequent doxorubicin dose reductions (30% vs. 7.2%; p = 0.006). The CYP3A4 inhibitor group did not differ from the no CYP inhibitor group for these outcomes. CONCLUSIONS: CYP inhibitors, particularly CYP2D6 inhibitors, may affect doxorubicin tolerability, as seen in this study by an increased incidence of unplanned medical visits and doxorubicin dose reductions.

Assessment of hospitalization rates for immune-related adverse events with immune checkpoint inhibitors.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) have become the standard of care in many cancer types. As the number of patients receiving ICIs for various cancers continues to expand, patients and practitioners should be aware of potentially severe immune-related adverse events (irAEs). Despite reports of the incidence of grade 3/4 toxicities, the proportion of patients whose symptoms were clinically severe enough to warrant hospitalization for adverse event management is unknown. METHODS: This single center, retrospective, observational study was designed to determine the impact of irAEs on patients and the hospital. Patients who started ICIs from May 2016 through May 2019 for melanoma or lung cancer were included. The primary outcome was incidence of hospitalization for irAE. Secondary outcomes included median length of hospitalization, time to onset of irAE, rates of hospitalization for irAE per each checkpoint inhibitor regimen, organ system affected, progression free survival, and overall survival. RESULTS: Of 384 patients with melanoma or lung cancer, 27 (7%) were hospitalized at our institution for an irAE. The most common irAE leading to hospitalization was colitis for patients with melanoma and pneumonitis for patients with lung cancer. The median length of stay across all hospitalizations was 10 days. Twenty-five patients required the use of corticosteroids while hospitalized, while eight of these patients required second line irAE treatment. For the total patient population, 34.7% experienced a grade 1/2 irAE and 13.1% experienced a grade 3/4 irAE. CONCLUSION: Our cohort of patients experienced similar rates irAEs as reported in clinical trials and published reports.

Orolingual Angioedema After Tissue Plasminogen Activator Administration in Patients Taking Angiotensin-Converting Enzyme Inhibitors.

Orolingual angioedema is a rare adverse effect (1%-5%) of tissue plasminogen activator (tPA) that can lead to significant morbidity in patients with acute ischemic stroke. It is thought that increased levels of bradykinin and histamine resulting from tPA administration can result in angioedema. Angiotensin-converting enzyme (ACE) inhibitors can also lead to increased levels of bradykinin and appear to be a risk factor for tPA-associated angioedema. A literature review was conducted to examine previous cases of orolingual angioedema associated with tPA administration in patients also taking ACE inhibitors to better understand the relationship between ACE inhibitors and tPA-induced angioedema. Over a 20-year period, 27 patients who experienced angioedema with tPA while on ACE inhibitor therapy were identified. In this patient population, the onset of angioedema symptoms appeared as soon as 15 min after the tPA bolus and as late as 2 hr after the tPA infusion. Most patients required a combination of supportive medications such as corticosteroids (81.5%), antihistamines (74%), and epinephrine (18.5%) for the management of angioedema. Severe presentations of orolingual angioedema resulted in intubation for airway protection (26%). Symptom resolution ranged from shortly after the administration of supportive medications to 72 hr after symptom onset. Orolingual angioedema after tPA administration has the potential to cause significant morbidity, indicating patients should be monitored closely for a few hours after administration for the development of airway compromise. ACE inhibitors should not be the preferred antihypertensive agents for patients who require blood pressure lowering prior to tPA administration.