Severe thrombocytopenia after trastuzumab retreatment: a case report

Severe thrombocytopenia after trastuzumab in a patient with HER2-positive serous endometrial cancer

Trastuzumab is a humanised, monoclonal antibody that interferes with the human epidermal growth factor receptor 2 (HER2)/neu receptor and binds selectively to the HERB2 protein. It has been shown to prolong survival of patients with HER2-positive advanced uterine serous carcinoma.We report the case of a woman in her 70s with HER2-positive metastatic papillary serous endometrial adenocarcinoma, who experienced severe thrombocytopenia related to trastuzumab administration. One week after the first dose of carboplatin/paclitaxel/trastuzumab combination chemotherapy, the patient was admitted to the hospital with vaginal bleeding, melena, petechiae and platelet counts of 0×109/L. The patient was suspected to have a severe trastuzumab-induced thrombocytopenia. A rapid and complete recovery was observed after multiple platelet transfusions, high-dose IV corticosteroids and immunoglobulin.Among the 13 reported cases of trastuzumab-induced thrombocytopenia, this is the first case reported in the literature occurring in a patient with a gynecologic malignancy.

Trastuzumab Associated With Recurrent Severe Thrombocytopenia and Successful Use of Pertuzumab Monotherapy

Trastuzumab is a mainstay chemotherapeutic agent used in the treatment of human epidermal growth factor receptor 2 (HER2)/neu-positive breast cancer that, though generally well-tolerated, is classically associated with side effects like cardiotoxicity. Cytopenias can be seen but are generally secondary to other chemotherapeutic agents used in conjunction with trastuzumab. Herein, we present a case of recurrent severe thrombocytopenia following trastuzumab use that resolved following discontinuation. Our patient then finished a year of maintenance therapy with pertuzumab alone and is still in remission four years later. This is the eleventh report of this severe adverse effect described in the literature. This report contributes to the body of work describing this severe side effect by illustrating a clear temporal relationship between trastuzumab and severe thrombocytopenia, while also providing an alternate treatment option with chemotherapy and pertuzumab monotherapy. Given that pertuzumab is typically only used in addition to trastuzumab, evidence of its successful independent use is of clinical value to patients who may not be able to tolerate trastuzumab.

Drug-induced thrombocytopenia associated with trastuzumab in a patient with HER2-positive recurrent gastric cancer

Here, we report a 57-year-old female patient with HER2-positive recurrent gastric cancer who experienced drug-induced thrombocytopenia associated with trastuzumab, a humanized anti-HER2 monoclonal antibody. Shortly after the initiation of S-1, oxaliplatin, and trastuzumab chemotherapy, the patient experienced severe thrombocytopenia and did not respond to platelet transfusions. Based on the findings of increased numbers of polynuclear megakaryocytes in the bone marrow and an elevated level of platelet-associated IgG (PA-IgG), the patient was diagnosed with drug-induced thrombocytopenia (DITP). The platelet count recovered rapidly with oral prednisolone (1 mg/kg). Since we initially suspected oxaliplatin as the causal agent, S-1 was restarted as a monotherapy, followed by trastuzumab after a 3-week interval, without oxaliplatin. On the second day after the addition of trastuzumab, severe thrombocytopenia occurred again, which suggests that trastuzumab was responsible for the DITP. The patient no longer experienced severe thrombocytopenia during the subsequent S-1 and oxaliplatin chemotherapy, which supports this hypothesis.

Severe thrombocytopenia induced by trastuzumab rechallenge: a case report and literature review

WHAT IS KNOWN AND OBJECTIVE

Trastuzumab can significantly prolong the survival of patients with human epidermal growth factor receptor-2 (HER-2)-positive breast cancer. Trastuzumab-induced thrombocytopenia is a rare adverse effect. There have been no reports of acute, grade 4 thrombocytopenia after weekly trastuzumab therapy. The study reports a case of a breast cancer patient with severe thrombocytopenia due to trastuzumab infusion (8 mg/kg). Moreover, the patient experienced recurrence of severe thrombocytopenia after receiving weekly trastuzumab therapy (4 mg/kg).

CASE SUMMARY

A 52-year-old woman with HER-2-positive breast cancer developed diffuse petechial haemorrhages and ecchymosis on the lower limbs and gingival bleeding within 24 hours of trastuzumab infusion (8 mg/kg). She was confirmed to have severe thrombocytopenia, which quickly recovered after corticosteroid therapy and platelet transfusion. When her platelet count recovered, we attempted weekly trastuzumab therapy (4 mg/kg); however, thrombocytopenia recurred within 24 hours. Thus, we did not attempt further treatment with trastuzumab.

WHAT IS NEW AND CONCLUSION

We are the first to attempt weekly trastuzumab therapy after thrombocytopenia induced by its initial administration. Reducing the trastuzumab dose did not prevent trastuzumab-induced thrombocytopenia. Unlike other reports with administration of high-dose corticosteroid, we found that a standard dose of corticosteroid combined with platelet transfusion was effective in treating trastuzumab-induced thrombocytopenia.

Trastuzumab-induced thrombocytopenia after eight cycles of trastuzumab treatment

Trastuzumab, a humanized monoclonal antibody derived from recombinant DNA, is used in patients with breast cancer with HER2 gene amplification. The survival benefit from trastuzumab has been well established in patients with early and metastatic breast cancer who had over expression of HER2. We reported a case of severe thrombocytopenia after eight cycles of trastuzumab treatment for breast cancer. Before the 9th trastuzumab treatment, the patient’s platelet decreased to 48 × 10⁹/L. Recombinant human thrombopoietin was used, and the platelet level increased to normal level. Before the 10th treatment, the platelet count of the patient was 99 × 10⁹/L. However, during the 10th and 11th trastuzumab treatment, the platelet count decreased to 5 × 10⁹/L in 24 h. After treatment with TPO and corticosteroids, the platelet levels increased to the normal level in 7 days. Trastuzumab-induced thrombocytopenia is rare but still occurred even after 8 cycles of trastuzumab treatment.

Species-Specific Involvement of Integrin αIIbβ3 in a Monoclonal Antibody CH12 Triggers Off-Target Thrombocytopenia in Cynomolgus Monkeys

CH12 is a novel humanized monoclonal antibody against epidermal growth factor receptor variant III (EGFRvIII) for cancer treatment. Unfortunately, in pre-clinical safety evaluation studies, acute thrombocytopenia was observed after administration of CH12 in cynomolgus monkeys, but not rats. More importantly, in vitro experiments found that CH12 can bind and activate platelets in cynomolgus monkey, but not human peripheral blood samples. Cynomolgus monkey-specific thrombocytopenia has been reported previously; however, the underlying mechanism remains unclear. Here, we first showed that CH12 induced thrombocytopenia in cynomolgus monkeys through off-target platelet binding and activation, resulting in platelet destruction. We subsequently found that integrin αIIbβ3 (which is expressed on platelets) contributed to this off-target toxicity. Furthermore, three-dimensional structural modeling of the αIIbβ3 molecules in cynomolgus monkeys, humans, and rats suggested that an additional unique loop exists in the ligand-binding pocket of the αIIb subunit in cynomolgus monkeys, which may explain why CH12 binds to platelets only in cynomolgus monkeys. Moreover, this study supported the hypothesis that the minor differences between cynomolgus monkeys and humans can confuse human risk assessments and suggests that species differences can help the prediction of human risks and avoid losses in drug development.