A multi-centre case series of alectinib-related erythrocyte membrane changes and associated haemolysis

Changes in Red Cell Morphology and Haematological Laboratory Parameters Associated With Alectinib

BACKGROUND

Alectinib is a second-generation anaplastic lymphoma kinase (ALK) inhibitor indicated for ALK-mutated non-small-cell lung cancer. Recently, the association between alectinib and red cell morphological abnormalities has been reported in a few case series. This retrospective observational study aims to determine the frequency of occurrence of acanthocytosis in patients taking alectinib and to evaluate the red cell indices, biochemical markers of haemolysis and eosin-5-maleimide (EMA) binding assay results in patients receiving alectinib.

METHODS

Patients who were on alectinib and had a complete blood count test performed in Queen Elizabeth Hospital Haematology Laboratory between 1 May 2021 and 31 August 2021 were included in the study. Haematological investigations that had been performed before and after the commencement of alectinib were reviewed.

RESULTS

Fifty patients receiving alectinib were evaluated in this analysis. One hundred per cent of patients showed 3+ acanthocytes on the peripheral blood smears. Compared with the test results before starting alectinib, the post-alectinib blood tests showed a significantly lower haemoglobin concentration, red blood cell count and haematocrit; and a significantly higher mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and red cell distribution width. All the tested patients showed a marked reduction in EMA mean channel fluorescence compared with normal control.

CONCLUSION

Our cohort revealed that alectinib caused significant acanthocytosis in all patients. Alectinib was also associated with changes in red cell indices and biochemical markers of haemolysis, compatible with a spherocytic and anisopoikilocytic morphology with haemolysis. Patients on alectinib had reduced EMA binding.

Alectinib-induced Hemolytic Anemia with Positive Direct Antiglobulin Test in a Patient with Lung Adenocarcinoma: A Possible Drug-drug Interaction Effect

Recent studies have reported that direct antiglobulin test (DAT) results were negative in cases of alectinib-induced hemolytic anemia with abnormal red blood cell (RBC) morphology. We herein report the case of a 72-year-old female patient who was diagnosed with alectinib-induced hemolytic anemia who - in contrast to previous reports - showed a positive DAT result. After discontinuing famotidine and alectinib, the DAT results turned negative; however, when alectinib was resumed, hemolysis recurred. Although alectinib-induced hemolytic anemia has been previously thought to be associated with abnormal morphological changes of the RBCs, we suggest that alectinib-induced anemia may manifest as DAT-positive immune hemolytic anemia because of a complementary effect with other drugs.

Alectinib-Induced Severe Hemolytic Anemia in a Patient with ALK-Positive Non-Small Cell Lung Cancer: A Case Report

Alectinib is a selective anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor as standard therapy for ALK-rearranged non-small cell lung cancer (NSCLC). Hemolytic anemia is considered as a rare but significant adverse event with alectinib. Here, we report a case of a 73-year-old female with lung adenocarcinoma, harbouring an ALK fusion gene, who received alectinib as second-line therapy and developed gradually progressive grade 4 (6.4 g/dL) drug-induced hemolytic anemia (DIHA) after complete response. We discontinued alectinib and performed a blood transfusion for the severe anemia. The anemia improved with no recurrence of lung adenocarcinoma over 10 months. Regular hematologic monitoring and the possibility of DIHA should be considered in case of progressive hemolytic anemia during alectinib treatment.

Successful Treatment with Brigatinib after Alectinib-Induced Hemolytic Anemia in Patients with Metastatic Lung Adenocarcinoma-A Case Series

Alectinib is a second-generation anaplastic lymphoma kinase (ALK) inhibitor used in the treatment of advanced ALK-rearrangement positive non-small-cell lung cancer (NSCLC). Many tolerable adverse events were reported with the use of Alectinib; nevertheless, hemolytic anemia was not mentioned in the safety analysis. In this case, series, we report four cases of Alectinib-induced oxidative hemolytic anemia and discuss different etiologic hypotheses on the underlying mechanism of such overlooked adverse event of the drug. Furthermore, we draw attention to the successful treatment with Brigatinib, an alternative second-generation ALK-inhibitor without recurrence of hemolytic anemia in three of our four cases, suggesting a probable class effect.

Early Development of Ubiquitous Acanthocytosis and Extravascular Hemolysis in Lung Cancer Patients Receiving Alectinib

Alectinib is a standard initial treatment for patients with advanced anaplastic lymphoma kinase (ALK) rearranged non-small-cell lung cancer (NSCLC). The current study analyzed a prospective cohort of 24 consecutive alectinib-treated patients and controls in order to comprehensively characterize longitudinal erythrocyte changes under treatment with ALK inhibitors. Upon starting alectinib, all examined patients developed reticulocytosis and abnormal erythrocyte morphology with anisocytosis and a predominance of acanthocytes (64% of red blood cells on average, range 36−100%) in the peripheral blood smear within approximately 2 weeks. Changes were accompanied by a gradual reduction in Eosin-5-maleimide (EMA) binding, which became pathologic (<80% of cells) within 1−2 months in all cases, mimicking an abortive form of hereditary spherocytosis. The latter could be ruled out in 3/3 of analyzed cases by normal sequencing results for the ANK1, EPB42, SLC4A1, SPTA1, or SBTB genes. The direct Coombs test was also negative in 11/11 tested cases. Besides, anemia, increased LDH, and increased bilirubin were noted in a fraction of patients only, ranging between 42 and 68%. Furthermore, haptoglobin decreases were infrequent, occurring in approximately 1/3 of cases only, and mild, with an average value of 0.93 g/L within the normal range of 0.3−2 g/dL, suggesting that hemolysis occurred predominantly in the extravascular compartment, likely due to splenic trapping of the deformed erythrocytes. These changes showed no association with progression-free survival under alectinib or molecular features, i.e., ALK fusion variant or TP53 status of the disease, and resolved upon a switch to an alternative ALK inhibitor. Thus, alectinib induces mild, reversible erythrocyte changes in practically all treated patients, whose most sensitive signs are aberrant red cell morphology in the peripheral smear, a pathologic EMA test, and reactive reticulocytosis. Frank hemolytic anemia is rare, but mild subclinical hemolysis is very frequent and poses differential-diagnostic problems. Alectinib can be continued under the regular control of hemolysis parameters, but the risk of long-term complications, such as cholelithiasis due to increased serum bilirubin in most patients, remains unclear at present.