Trastuzumab-Induced Interstitial Pneumonitis

Trastuzumab is a recombinant immunoglobulin G1 monoclonal antibody used to treat human epidermal growth factor receptor 2 (HER2) cancers. Trastuzumab-induced interstitial pneumonitis is a rare adverse effect reported in a few patients. Interstitial pneumonitis presents as symptoms of dyspnea, hypoxia, cough, and fever. If the patient is treated early, corticosteroids can slow or reverse the disease progression. A 41-year-old woman presented with dyspnea and a dry cough three weeks after her third cycle of trastuzumab therapy for breast cancer. A diagnosis of trastuzumab-induced interstitial pneumonitis was made after multiple other disease processes were ruled out. The patient was started on methylprednisolone while inpatient and transitioned to prednisone for outpatient therapy. The patient was maintained on 2-3L of oxygen throughout her hospital stay and was discharged on 3L of oxygen through nasal cannula. Trastuzumab was never restarted after discharge. There have been many trials evaluating the safety, efficacy, and optimal treatment regimen of trastuzumab, but there are only a few reports of interstitial pneumonitis adverse reaction. The lack of correlation and limited cases make this adverse effect very difficult to diagnose and monitor. New trials and case reports can bring an insight into contributing factors, symptoms at onset, and treatment for future patients. With the increase in use of trastuzumab therapy, physicians should be aware of how to diagnose and treat the rare adverse reaction of trastuzumab-induced interstitial pneumonitis.

Pathologic Complete Response Achieved in Early-Stage HER2-Positive Breast Cancer After Neoadjuvant Therapy With Trastuzumab and Chemotherapy vs. Trastuzumab, Chemotherapy, and Pertuzumab: A Systematic Review and Meta-Analysis of Clinical Trials

Patients diagnosed with human epidermal growth factor receptor 2 (HER2)-positive breast cancer require treatment upfront because of the aggressive nature of this type of cancer. Patients with early-stage HER2-positive breast cancer are usually treated with neoadjuvant therapy. This neoadjuvant therapy comprises targeted therapy and chemotherapy. Targeted therapy is given with trastuzumab. Pertuzumab is either administered or not with trastuzumab as a targeted therapy. This systematic review and meta-analysis aim to find out and compare the benefit achieved in terms of pathologic complete response (pCR) by adding pertuzumab to the neoadjuvant treatment regimen for early-stage HER2-positive breast cancer patients. Various databases were searched to find out relevant clinical trials. After going through PubMed, Embase, and Cochrane, three clinical trials were shortlisted for this systematic review and meta-analysis. These three clinical trials were double-armed. Pertuzumab was present in one arm while being absent in one arm to assess the benefit of adding pertuzumab in terms of pCR achieved. Data were analyzed using RevMan Web (Cochrane, London, UK). The odds ratio and 95% confidence interval were calculated for the outcome. The Mantel-Haenszel method and random effect model were used for analysis. The risk of bias in studies was evaluated using the Cochrane risk of bias tool for randomized controlled trials (ROB2). The summary statistics showed that the incidence of pCR was more in the experimental group (having pertuzumab) as compared to the control group (without pertuzumab) with an odds ratio of 2.10 (95% CI: 1.56-2.83) with I2 = 0%. In three double-arm trials, there were 840 participants, 445 in the experimental group and 395 in the control group. A total of 203 (45%) patients out of 445 in the experimental group achieved pCR, whereas 127 (32%) patients out of 395 in the control group achieved pCR. Through the results of this study, it can be concluded that the rate of pCR achieved was higher in that arm in which pertuzumab was present compared to the study arm in which only trastuzumab was given as targeted therapy. Thus, it can be suggested that pertuzumab be added to the neoadjuvant regimen for early-stage HER2-positive breast cancer patients. This would result in achieving a better pCR. And by improving pCR rates, the survival outcomes of patients can be significantly improved.