Trastuzumab deruxtecan (T-DXd) is a novel anti-HER2 antibody-drug conjugate formed by the combination of trastuzumab and deruxtecan. It is used in human epidermal growth factor 2 receptor (HER2) mutant breast, stomach and colorectal cancers as well as non-small cell lung cancer (NSCLC). The 58-year-old denovo metastatic NSCLC patient we will discuss here progressed with newly developing brain metastasis under first-line carboplatin/paclitaxel treatment. After next generation sequencing revealed a mutation in the ERBB2 gene located in exon 20, we administered T-DXd to our patient. While a significant improvement was observed in the clinical condition of the patient after one course of treatment, brain metastases were found to be in complete response in control screening after four courses of treatment. Systemic screening with PET/computed tomography showed nearly complete regression of the primary lesion, metastatic lymphadenopathies, and surrenal metastases. T-DXd may be successfully used in HER2 mutant metastatic NSCLC patients. In addition, it can also be successfully used in patients with central nervous system metastases with or without cranial radiotherapy.

Breast cancer (BC) is the prevailing malignancy among women, with HER2 overexpression observed in 20-30 % of all BC, thereby serving as a prognostic indicator for unfavorable outcomes in affected individuals. There is a necessity to establish innovative treatment protocols to expand the therapeutic alternatives accessible for managing HER2-positive BC. In this study, we report a case of HER2-positive BC that was managed in our department using a combination of three targeted drugs (Trastuzumab, Pertuzumab and Pyrotinib) along with chemotherapy. The treatment resulted in a pathological complete response (pCR) and was observed to be well-tolerated, without any significant adverse reactions. Hence, the combination of Pyrotinib and Dual HER2 blockade treatment shows promise as a neoadjuvant therapy for locally advanced HER2-positive BC to achieve a pCR in surgery. Nevertheless, this conclusion necessitates additional validation via meticulously designed clinical research investigations encompassing larger patient populations.

UNASSIGNED: Neuro-Behcet\'s disease (NBD) is a variant of Behcet\'s disease (BD). To our knowledge, there have been no previous reports on concurrent NBD in breast cancer patients undergoing chemotherapy.
UNASSIGNED: Our patient had a history of BD and was asymptomatic. She was diagnosed with human epidermal growth factor receptor 2-positive breast cancer by core needle biopsy and was administered neoadjuvant chemotherapy. After four courses, in addition to the aggravation of the existing adverse events, headache, fever, dysarthria, and muscle weakness in the upper left and lower extremities appeared. On admission, she was diagnosed with acute NBD, and steroid therapy was initiated. After her symptoms improved gradually, she was discharged. Then, she underwent mastectomy and axillary lymph node dissection for breast cancer. Trastuzumab and pertuzumab plus tamoxifen were administered postoperatively. Two years postoperatively, no recurrence of breast cancer and NBD was noted.
UNASSIGNED: When chemotherapy is administered to breast cancer patients with a history of BD, it is necessary to select chemotherapy with as few adverse events as possible and to continue with treatment while paying attention to the risk of NBD.

Inflammatory breast cancer (IBC) is a rare, aggressive form of breast cancer characterized by poor prognosis. The treatment requires a multidisciplinary approach, with neoadjuvant chemotherapy, surgery, and radiation therapy (RT). Particularly, high doses of conventional RT have been historically delivered in the adjuvant setting after chemotherapy and mastectomy or as radical treatment in patients ineligible for surgery. Here, we report the case of a 49-year-old woman patient with IBC unsuitable for surgery and treated with a combination of lattice RT and fractionated external beam RT concurrent with trastuzumab, with a curative aim. One year after RT, the patient showed a complete response and tolerable toxicities. This is the first reported case of a not-operable IBC patient treated with this particular kind of RT.

Toxic Epidermal Necrolysis (TEN) is a rare, but potentially fatal mucocutaneous reaction, that may occur due to an immunologic response to certain medications. However, TEN triggered by Trastuzumab is extremely rare. Early diagnosis, recognition, and prompt cessation of the offending drugs and initiation of steroid therapy with supportive management are the most important actions for managing TEN. Although rare, it is important to be vigilant about this potential adverse reactions associated with trastuzumab to ensure patient safety and contribute to better outcomes.

Pulmonary lymphangitis carcinomatosis is generally characterized by resistance to chemotherapy and is associated with a poor prognosis. Herein, we present a case of pulmonary lymphangitic carcinomatosis from recurrent breast cancer that responded well to trastuzumab deruxtecan(T-DXd). The patient was a 40-year-old woman with hormone receptor-positive, HER2-positive breast cancer. At the age of 31, she had undergone a left mastectomy with axillary lymph node dissection. She received adjuvant chemotherapy(5-fluorouracil-epirubicin-cyclophosphamide, docetaxel, and trastuzumab)followed by endocrine therapy(tamoxifen and LH-RHa). Three years after the surgery, pulmonary and bone metastases were detected and she was treated with trastuzumab, pertuzumab, and capecitabine. Liver metastases were detected, and she was treated with trastuzumab emtansine. Nine years after surgery, the patient developed dyspnea and was diagnosed with lymphangitis carcinomatosis. After initiating T-DXd, dyspnea rapidly improved, and ground glass opacity on CT scan disappeared. She responded well to the treatment, with prolonged, stable disease for 1 year and 2 months. Thus, T-DXd may be effective against pulmonary lymphangitis carcinomatosis, which is generally characterized by resistance to chemotherapy.

UNASSIGNED: Radiation recall dermatitis (RRD) is a localized drug-induced inflammatory skin reaction occurring exclusively in a previously irradiated site months to years after discontinuation of ionizing radiation. The symptoms of RRD can range from mild redness to extensive dermatitis. Antineoplastic drugs such as doxorubicin, docetaxel, paclitaxel, and gemcitabine are most commonly associated with radiation recall reactions. These reactions can also occur with antibiotics and anti-tubercular drugs.
METHODS: A 38-years-old woman with hormone receptor-negative, HER2-positive inflammatory breast cancer (right), clinical stage cT4dN1Mx, received neoadjuvant chemotherapy with AC > TH protocol at 3 weeks intervals (Anthracycline-Doxorubicin plus Cyclophosphamide X 4 cycles, then docetaxel plus Trastuzumab X 4 cycles) followed by modified radical mastectomy followed by adjuvant locoregional radiotherapy. She received the 5th cycle and 6th cycle trastuzumab monotherapy just before the start of surgery and radiotherapy, respectively. After 1 month of completion of radiotherapy, during her seventh cycle of Trastuzumab monotherapy, she developed mild edema with erythematous change over the previously irradiated area with fever. A skin biopsy was taken to exclude any recurrence; however, no evidence of malignancy was found.
UNASSIGNED: We diagnosed it as a case of RRD. We managed her conservatively. Later, she was rechallenged with the same dose in subsequent cycles with systemic steroid coverage, which she tolerated very well, except for the reappearance of mild erythema following each cycle of maintenance dose of Trastuzumab.
CONCLUSIONS: Radiation recall dermatitis is an extremely rare phenomenon; hence, an acquaintance of clinicians with this rare entity is essential for timely diagnosis and appropriate management.

BACKGROUND: Extramammary Paget\'s disease (EMPD) is a rare cancer that occurs within the epithelium of the skin, arising predominantly in areas with high apocrine gland concentration such as the vulva, scrotum, penis and perianal regions. Here, we aim to integrate clinicopathological data with genomic analysis of aggressive, rapidly-progressing de novo metastatic EMPD responding to HER2-directed treatment in combination with other agents, to attain a more comprehensive understanding of the disease landscape.
METHODS: Immunohistochemical staining on the scrotal wall tumor and bone marrow metastasis demonstrated HER2 overexpression. Whole genome sequencing of the tumor and matched blood was performed.
RESULTS: Notable copy number gains (log2FC > 0.9) on chromosomes 7 and 8 were detected (n = 81), with 92.6% of these unique genes specifically located on chromosome 8. Prominent cancer-associated genes include ZNF703, HOOK3, DDHD2, LSM1, NSD3, ADAM9, BRF2, KAT6A and FGFR1. Interestingly, ERBB2 gene did not exhibit high copy number gain (log2FC = 0.4) although 90% of tumor cells stained HER2-positive. Enrichment in pathways associated with transforming growth factor-beta (TGFβ) (FDR = 0.0376, Enrichment Ratio = 8.12) and fibroblast growth factor receptor (FGFR1) signaling (FDR = 0.0082, Enrichment Ratio = 2.3) was detected. Amplicon structure analysis revealed that this was a simple-linear amplification event.
CONCLUSIONS: Whole genome sequencing revealed the underlying copy number variation landscape in HER2-positive metastatic EMPD. The presence of alternative signalling pathways and genetic variants suggests potential interactions with HER2 signalling, which possibly contributed to the HER2 overexpression and observed response to HER2-directed therapy combined with other agents in a comprehensive treatment regimen.

BACKGROUND: HER2 positive disease accounts for 15-20% of early breast cancer. Achieving a pathological complete response after neoadjuvant chemotherapy (NACT) improves prognosis and decreases risk of recurrence.
METHODS: Our case report aimed to highlight an emblematic clinical success and benefit of NACT with the addition of pertuzumab to the standard trastuzumab/taxane/anthracycline combination in a patient with a 9 cm breast neoplasm and extensive lymph node involvement (>4 pathological lymph nodes).
CONCLUSIONS: Achieving a complete pathological response with NACT, should be the main goal, especially in patients with triple negative and HER2 positive breast cancer.

A 67-year-old man visited our hospital for epigastric pain. Esophagogastroduodenoscopy(EGD)revealed type 2 gastric cancer from the cardia to the gastric angle, and histopathological examination revealed papillary adenocarcinoma(pap), HER2-positive. Contrast-enhanced CT showed wall thickening mainly in the posterior wall of the gastric body, enlarged lymph nodes that were lumped together with the main lesion, and 8 low-absorption areas with ring shaped contrast effects in both lobes of the liver. The patient was diagnosed as gastric cancer cT4aN(+)M1[HEP], clinical Stage ⅣB. Six courses of capecitabine plus cisplatin plus trastuzumab(XP plus Tmab)therapy and 17 courses of capecitabine plus trastuzumab(X plus Tmab)therapy were performed. After chemotherapy, liver and lymph node metastases disappeared on CT and MRI. EGD showed residual gastric cancer, and the policy was to resect the primary tumor. Laparoscopic total gastrectomy with D2 lymph node dissection was performed. Pathological results showed T1b(SM)depth, no lymph node metastasis, and histologic response was Grade 2a. Six courses of X plus Tmab were administered as postoperative adjuvant chemotherapy, but were discontinued at the patient\'s request. Currently, 5 years have passed since the first chemotherapy and 3.5 years have passed since the surgery, and the patient is alive without recurrence, suggesting that the conversion surgery may have contributed to the prolonged survival.