Phase II study of nanoparticle albumin-bound paclitaxel monotherapy for relapsed non-small cell lung cancer with patient-reported outcomes (NLCTG1302).

Background: This multicenter, open-label, single-arm phase II study [Niigata Lung Cancer Treatment Group (NLCTG) 1302] was conducted to evaluate the efficacy and safety of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) monotherapy for previously treated patients with advanced non-small cell lung cancer (NSCLC). We also investigated chemotherapy-induced peripheral neuropathy (CIPN) to evaluate the quality of life (QOL). Methods: Sixty-five patients with advanced NSCLC from 14 participating institutions who had previously undergone one or two cytotoxic chemotherapy regimens were enrolled in this study. The patients received 100 mg/m2 nab-paclitaxel intravenously on days 1, 8, and 15, every 4 weeks. The primary endpoint was overall objective response rate. CIPN symptoms were prospectively assessed using the Patient Neurotoxicity Questionnaire (PNQ) and Common Terminology Criteria for Adverse Events (CTCAE). Results: The overall response rate (ORR) was 18.5% [95% confidence interval (CI): 10.9-29.6%], and the median progression-free survival (PFS) was 3.4 (95% CI: 2.5-4.3) months. Median overall survival (OS) was 8.6 (95% CI: 7.1-10.2) months. The most common non-hematologic grade ≥3 adverse events were infection (7.7%) and hyponatremia (4.6%). Neutropenia was the most common grade 3 or 4 adverse event (30.8%), and febrile neutropenia developed in 6.2% patients. The PNQ and CTCAE scores for motor peripheral neuropathy were low (kappa =0.10). Conclusions: The primary endpoint was achieved. Nab-paclitaxel was well tolerated and showed anti-tumor activity in patients with previously treated NSCLC. This study demonstrates a low degree of concordance in CIPN grading between physicians and patients. Trial Registration: University hospital Medical Information Network Clinical Trial Registry (ID: UMIN000012343).

Observational study of rebiopsy in EGFR-TKI-resistant patients with EGFR mutation-positive advanced NSCLC.

The identification of acquired resistance mutations has been essential in non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) active mutations. Rebiopsy plays a pivotal role in selecting the optimal treatment for patients who develop resistance to initial EGFR-tyrosine kinase inhibitors (EGFR-TKIs). This multicenter, observational study was conducted to investigate the details of rebiopsy in Japanese clinical practice. The primary endpoints were the implementation rate of rebiopsy and the concordance rate for T790M mutation detection between histological and cytological specimens using the cobas EGFR Mutation Test, version 2. One hundred ninety-four patients with EGFR-mutant NSCLC were enrolled, and 120 patients developed acquired resistance to EGFR-TKIs. The median age was 68 years (range 20-87), and 52.5% of the patients were women. Rebiopsy was performed in 109 patients, and the implementation rate of rebiopsy was 90.8%. The success rates of rebiopsy in the total, histology, cytology and liquid biopsy populations were 67.9%, 81.3%, 66.7% and 43.8%, respectively. The positive percent agreement and the negative percent agreement in the detection of the T790M mutation between the histological and cytological specimens were both 90.9%. Obtaining histological or cytological tissue samples at rebiopsy may contribute to improving the detection rate of the T790M mutation (trial registration number: UMIN000026019).

The Prognostic Significance of the Continuous Administration of Anti-PD-1 Antibody via Continuation or Rechallenge After the Occurrence of Immune-Related Adverse Events.

OBJECTIVES: Although immune checkpoint inhibitors (ICIs) have been shown to improve overall survival (OS) in advanced non-small-cell lung cancer (NSCLC) patients, ICIs sometimes cause various types of immune-related adverse events (irAEs), which lead to the interruption of ICI treatment. This study aims to evaluate the clinical significance of the continuation of ICIs in NSCLC patients with irAEs and to assess the safety and efficacy of the readministration of ICIs after their discontinuation due to irAEs. METHODS: We retrospectively identified patients with advanced NSCLC who were treated with first- to third-line anti-programmed cell death-1 (PD-1) therapy from January 2016 through October 2017 at multiple institutions belonging to the Niigata Lung Cancer Treatment Group. Progression-free survival (PFS) and OS from the initiation of ICI treatment were analyzed in patients with and without irAEs, with and without ICI interruption, and with and without ICI readministration. A 6-week landmark analysis of PFS and OS was performed to minimize the lead-time bias associated with time-dependent factors. RESULTS: Of 231 patients who received anti-PD-1 antibodies, 93 patients (40%) developed irAEs. Of 84 eligible patients with irAEs, 32 patients (14%) continued ICIs, and OS was significantly longer in patients who continued ICIs than that in patients who discontinued ICIs [not reached (95% CI: NE-NE) vs. not reached (95% CI: 22.4-NE); p = 0.025]. Of 52 patients who discontinued ICIs, 14 patients (6.1%) readministered ICIs, and OS in patients with ICI readministration was significantly longer than that in patients without ICI readministration [not reached (95% CI: NE-NE) vs. not reached (95% CI: 8.4-NE); p = 0.031]. CONCLUSION: The current study demonstrated that both the continuation and readministration of ICIs after irAE occurrence improved OS compared to the permanent interruption of ICIs in NSCLC patients with ICI-related irAEs.

Subsequent systemic therapy for non-small cell lung cancer patients with immune checkpoint inhibitor-related interstitial lung disease.

BACKGROUND: Although immune checkpoint inhibitors (ICIs) are effective for advanced non-small cell lung cancer (NSCLC), ICIs may cause interstitial lung disease (ILD), which results in treatment discontinuation and is sometimes fatal. Despite the high incidence of ICI-related ILD, there are few cancer treatment options for patients. This study aimed to evaluate the safety and efficacy of subsequent systemic cancer therapy in NSCLC patients with ICI-related ILD. METHODS: We retrospectively assessed NSCLC patients who received programmed cell death-1 (PD-1) inhibitors as first- to third-line therapy at participating institutions of the Niigata Lung Cancer Treatment Group from January 2016 to October 2017. RESULTS: This analysis included 231 patients, 32 (14%) of whom developed ICI-related ILD. Of these patients, 16 (7%) received subsequent systemic cancer treatments. The median overall survival (OS) tended to be longer in the systemic cancer therapy group than in the no systemic cancer therapy group [22.2 months (95% CI: 1-NE) vs. 4.5 months (95% CI: 1-NE); P=0.067]. ICI-related ILD recurred in half of the patients who received systemic cancer therapy, and the median OS tended to be shorter in patients with recurrent ICI-related ILD [22.0 months (95% CI: 1-NE) vs. 7.0 months (95% CI: 1-NE); P=0.3154]. CONCLUSIONS: According to the current study, systemic cancer treatment is effective in patients with ICI-related ILD; however, its safety is uncertain because of the high risk of ICI-related ILD recurrence and poor survival outcome following ILD recurrence.

A prospective phase II study of multimodal prophylactic treatment for afatinib-induced adverse events in advanced non-small cell lung cancer (Niigata Lung Cancer Treatment Group 1401).

BACKGROUND: Afatinib has shown clinical benefits in patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations. Many patients treated with afatinib experience skin or gastrointestinal toxicity. However, an effective management strategy has not been established. This prospective study was conducted to evaluate the efficacy of multimodal prophylactic treatment for afatinib-induced toxicity. METHODS: This single-arm prospective study was conducted to evaluate the efficacy of multimodal prophylactic treatment for afatinib-induced toxicity in patients with EGFR mutation positive advanced NSCLC who planned to receive a 40 mg dose of afatinib. Eligible patients were treated with oral loperamide (2 mg twice per day), prophylactic minocycline (100 mg once per day), topical medium-class steroids, and gargling with sodium azulene. The primary endpoint was the ability of prophylactic loperamide to prevent severe or intolerable diarrhea during the 4 weeks after the initial administration of afatinib. The incidence, severity and time to occurrence of diarrhea, rash, oral mucositis and paronychia were evaluated based on a daily patient questionnaire. RESULTS: Forty-six patients were enrolled. The primary endpoint analysis was performed in 35 patients as the per-protocol (PP) population. The 4-week successful prophylaxis rate for severe or intolerable diarrhea was 82.9% (90% confidence interval: 70.1-91.9%). In the total population, the incidences of grade 3 or higher rash, oral mucositis and paronychia within 4 weeks were 4%, 2% and 4%, respectively. CONCLUSIONS: Prophylactic loperamide administration was not effective in preventing severe or intolerable diarrhea during afatinib treatment. Adequate dose reduction will be a better approach to manage afatinib-induced diarrhea. Multimodal prevention using minocycline, topical steroids and gargling with sodium azulene may be helpful to maintain compliance with afatinib treatment (UMIN000016167).

Prognostic significance of the radiologic features of pneumonitis induced by anti-PD-1 therapy.

BACKGROUND: Interstitial lung disease (ILD) induced by anti-programmed-cell death-1 (PD-1) and anti-PD-ligand 1 (PD-L1) is potentially life-threatening and is a common reason of the discontinuation of therapy. In contrast, an enhancement in antitumor effects was reported in patients who developed immune-related adverse events, including ILD. Although recent evidence suggests that radiologic patterns of ILD may reflect the severity of ILD and the antitumor immune responses to anti-PD-1/PD-L1 therapies, the association between radiologic features and clinical outcomes remains unclear. METHODS: Patients with advanced non-small-cell lung cancer who were treated with 1st to 3rd line anti-PD-1 therapy from January 2016 through October 2017 were identified at multiple institutions belonging to the Niigata Lung Cancer Treatment Group. ILD was diagnosed by the treating physicians, and chest computed tomography scans were independently reviewed to assess the radiologic features of ILD. RESULTS: A total of 231 patients who received anti-PD-1 therapy were enrolled. Thirty-one patients (14%) developed ILD. Sixteen patients were classified as having ground glass opacities (GGO), 16 were classified as having cryptogenic organizing pneumonia (COP), and one was classified as having pneumonitis not otherwise specified. Patients with GGO had significantly worse overall survival time compared to patients with COP (7.8 months (95% CI: 2.2-NE) versus not reached (95% CI: 13.2-NE); P = 0.0175). Multivariate analysis of all 231 patients also revealed that PS = 1 and ≥2 and GGO were significant predictors of a worse overall survival. CONCLUSIONS: This study demonstrated that patients who developed GGO exhibited worse outcomes among non-small-cell lung cancer patients receiving anti-PD-1 therapies.

Efficacy of EGFR-TKIs with or without upfront brain radiotherapy for EGFR-mutant NSCLC patients with central nervous system metastases.

BACKGROUND: Although the clinical efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) patients has been demonstrated, their efficacy in EGFR-mutant NSCLCs with central nervous system (CNS) metastases and the role of radiotherapy remain unclear. This study aimed to determine if it is preferable to add upfront cranial radiotherapy to EGFR-TKIs in patients with EGFR-mutant NSCLC with newly diagnosed brain metastases. METHODS: We retrospectively analyzed the data of EGFR-mutant NSCLC patients with CNS metastases who received EGFR-TKIs as a first-line therapy. RESULTS: A total of 104 patients were enrolled and 39 patients received upfront brain radiotherapy, while 65 patients received first and second generation EGFR-TKIs first. The median time to treatment failure (TTF) was 7.8 months (95% confidence interval [CI]: 6.3-9.4). The median survival time (MST) was 24.0 months (95% CI: 20.1-30.1). The overall response rate of the CNS was 37%. The median CNS progression-free survival (PFS) was 13.2 months (95% CI: 10.0-16.2). Brain radiotherapy prior to EGFR-TKI prolonged TTF (11.2 vs. 6.8 months, P = 0.038) and tended to prolong CNS-PFS (15.6 vs. 11.1 months, P = 0.096) but was not significantly associated with overall survival (MST 26.1 vs. 24.0 months, P = 0.525). Univariate and multivariate analyses indicated that poor performance status and the presence of extracranial metastases were poor prognostic factors related to overall survival. CONCLUSION: EGFR-TKI showed a favorable effect for EGFR-mutant NSCLC patients with CNS metastases. Prolonged TTF and CNS-PFS were observed with upfront brain radiotherapy.

Nephrotoxicity of cisplatin combination chemotherapy in thoracic malignancy patients with CKD risk factors.

BACKGROUND: Nephrotoxicity is the major side effect that limits the dose of cisplatin that can be safely administered, and it is a clinical problem in cancer patients who received cisplatin combination chemotherapy. Recent evidence has demonstrated that patients with chronic kidney disease (CKD) have an increased risk of developing acute kidney injury (AKI). The present study was conducted to evaluate the prevalence of CKD risk factors in patients who received cisplatin and to assess the correlation between CKD risk factors and cisplatin-induced AKI. METHODS: We retrospectively analyzed 84 patients treated with cisplatin combination chemotherapy for thoracic malignancies. AKI was defined as a decrease in the estimated glomerular filtration rate (eGFR) > 25% from base line, an increase in the serum creatinine (sCre) level of > 0.3 mg/dl or ≥ 1.5 times the baseline level. RESULTS: Eighty of the 84 patients (95.2%) had at least one risk factor for CKD. All enrolled patients received cisplatin with hydration, magnesium supplementation and mannitol. Cisplatin-induced AKI was observed in 18 patients (21.4%). Univariate analysis revealed that cardiac disease and use of non-steroidal anti-inflammatory drugs (NSAIDs) were associated with cisplatin-induced nephrotoxicity (odds ratios [OR] 6 and 3.56, 95% confidence intervals [CI] 1.21-29.87 and 1.11-11.39, p = 0.04 and p = 0.04, respectively). Multivariate analysis revealed that cisplatin nephrotoxicity occurred significantly more often in patients with both risk factors (OR 13.64, 95% CI 1.11-326.83, p = 0.04). Patients with more risk factors for CKD tended to have a greater risk of developing cisplatin-induced AKI. CONCLUSIONS: We should consider avoiding administration of cisplatin to patients with CKD risk factors, particularly cardiac disease and NSAID use.

Critical Roles of Chemoresistant Effector and Regulatory T Cells in Antitumor Immunity after Lymphodepleting Chemotherapy.

Antitumor immunity is augmented by cytotoxic lymphodepletion therapies. Adoptively transferred naive and effector T cells proliferate extensively and show enhanced antitumor effects in lymphopenic recipients. Although the impact of lymphodepletion on transferred donor T cells has been well evaluated, its influence on recipient T cells is largely unknown. The current study demonstrates that both regulatory T cells (Tregs) and effector CD8(+) T cells from lymphopenic recipients play critical roles in the development of antitumor immunity after lymphodepletion. Cyclophosphamide (CPA) treatment depleted lymphocytes more efficiently than other cytotoxic agents; however, the percentage of CD4(+)CD25(+) Foxp3(+) Tregs was significantly increased in CPA-treated lymphopenic mice. Depletion of these chemoresistant Tregs following CPA treatment and transfer of naive CD4(+) T cells augmented the antitumor immunity and significantly suppressed tumor progression. Further analyses revealed that recipient CD8(+) T cells were responsible for this augmentation. Using Rag2(-/-) mice or depletion of recipient CD8(+) T cells after CPA treatment abrogated the augmentation of antitumor effects in CPA-treated reconstituted mice. The transfer of donor CD4(+) T cells enhanced the proliferation of CD8(+) T cells and the priming of tumor-specific CD8(+) T cells originating from the lymphopenic recipients. These results highlight the importance of the recipient cells surviving cytotoxic regimens in cancer immunotherapies.

Advanced thymic cancer treated with carboplatin and paclitaxel in a patient undergoing hemodialysis.

A 53-year-old man with an asymptomatic anterior mediastinal tumor undergoing hemodialysis was referred to our institution. He was diagnosed with thymic basaloid carcinoma based on the findings of a chest tomography-guided biopsy and successfully treated with carboplatin (300 mg/m(2)/day) and paclitaxel (200 mg/m(2)/day) on day 1 for six three-week cycles. To our knowledge, this is the first report regarding the efficiency of a carboplatin dose-definition method based on the body surface area with paclitaxel in a hemodialysis patient. This report may therefore be useful for treating hemodialysis patients who are candidates for carboplatin and paclitaxel therapy.

DDX3X induces primary EGFR-TKI resistance based on intratumor heterogeneity in lung cancer cells harboring EGFR-activating mutations.

The specific mechanisms how lung cancer cells harboring epidermal growth factor receptor (EGFR) activating mutations can survive treatment with EGFR-tyrosine kinase inhibitors (TKIs) until they eventually acquire treatment-resistance genetic mutations are unclear. The phenotypic diversity of cancer cells caused by genetic or epigenetic alterations (intratumor heterogeneity) confers treatment failure and may foster tumor evolution through Darwinian selection. Recently, we found DDX3X as the protein that was preferentially expressed in murine melanoma with cancer stem cell (CSC)-like phenotypes by proteome analysis. In this study, we transfected PC9, human lung cancer cells harboring EGFR exon19 deletion, with cDNA encoding DDX3X and found that DDX3X, an ATP-dependent RNA helicase, induced CSC-like phenotypes and the epithelial-mesenchymal transition (EMT) accompanied with loss of sensitivity to EGFR-TKI. DDX3X expression was associated with upregulation of Sox2 and increase of cancer cells exhibiting CSC-like phenotypes, such as anchorage-independent proliferation, strong expression of CD44, and aldehyde dehydrogenase (ALDH). The EMT with switching from E-cadherin to N-cadherin was also facilitated by DDX3X. Either ligand-independent or ligand-induced EGFR phosphorylation was inhibited in lung cancer cells that strongly expressed DDX3X. Lack of EGFR signal addiction resulted in resistance to EGFR-TKI. Moreover, we found a small nonadherent subpopulation that strongly expressed DDX3X accompanied by the same stem cell-like properties and the EMT in parental PC9 cells. The unique subpopulation lacked EGFR signaling and was highly resistant to EGFR-TKI. In conclusion, our data indicate that DDX3X may play a critical role for inducing phenotypic diversity, and that treatment targeting DDX3X may overcome primary resistance to EGFR-TKI resulting from intratumor heterogeneity.

[A case of thymic cancer effectively treated by weekly paclitaxel combined with carboplatin].

A 65-year-old woman with left chest pain, back pain, and palpitation that had persisted for 2 months was referred to our hospital. Computed tomography of her chest showed an anterior mediastinal tumor with mediastinal lymphadenopathy, left pleural effusion, and pericardial effusion. Endobronchial ultrasound-guided transbronchial needle aspiration of the subcarinal lymphadenopathy was performed. The pathological findings and other examinations such as bone scintigraphy suggested advanced thymic cancer (stage IV b according to the Masaoka classification of thymic epithelial tumors). The patient was treated with combination chemotherapy of carboplatin(area under the curve [AUC]=6, 656 mg/body, day 1) and weekly paclitaxel (70 mg/m², 100 mg/body, days 1, 8, and 15). After 4 cycles of chemotherapy, a partial response was achieved and the pericardial effusion disappeared. The patient did not experience any severe toxicity, except for grade 1 nausea, grade 2 anemia, and grade 2 alopecia. Weekly paclitaxel combined with carboplatin appears to be a useful regimen with minimal toxicity for advanced thymic cancer.

DEAD/H (Asp-Glu-Ala-Asp/His) box polypeptide 3, X-linked is an immunogenic target of cancer stem cells.

Accumulating evidence suggests that most solid malignancies consist of heterogeneous tumor cells and that a relatively small subpopulation, which shares biological features with stem cells, survives through potentially lethal stresses such as chemotherapy and radiation treatment. Since the survival of this subpopulation of cancer stem cells (CSC) plays a critical role in recurrence, it must be eradicated in order to cure cancer. We previously reported that vaccination with CD133(+) murine melanoma cells exhibiting biological CSC features induced CSC-specific effector T cells. These were capable of eradicating CD133(+) tumor cells in vivo, thereby curing the parental tumor. In the current study, we indicated that DEAD/H (Asp-Glu-Ala-Asp/His) box polypeptide 3, X-linked (DDX3X) is an immunogenic protein preferentially expressed in CD133(+) tumor cells. Vaccination with DDX3X primed specific T cells, resulting in protective and therapeutic antitumor immunity. The DDX3X-primed CD4(+) T cells produced CD133(+) tumor-specific IFNγ and IL-17 and mediated potent antitumor therapeutic efficacy. DDX3X is expressed in various human cancer cells, including lung, colon, and breast cancer cells. These results suggest that anti-DDX3X immunotherapy is a promising treatment option in efforts to eradicate CSC in the clinical setting.

The efficacy of triplet antiemetic therapy with 0.75 mg of palonosetron for chemotherapy-induced nausea and vomiting in lung cancer patients receiving highly emetogenic chemotherapy.

BACKGROUND: Chemotherapy-induced nausea and vomiting (CINV) are some of the most problematic symptoms for cancer patients. Triplet therapy consisting of a 5HT3 receptor antagonist, aprepitant, and dexamethasone is a guideline-recommended antiemetic prophylaxis for highly emetogenic chemotherapy (HEC). The efficacy and safety of triplet therapy using a 0.75-mg dose of palonosetron have not yet been investigated. We performed a prospective phase II study using triplet antiemetic therapy with 0.75 mg of palonosetron. METHODS: Chemotherapy-naïve lung cancer patients scheduled to receive HEC were enrolled. The eligible patients were pretreated with antiemetic therapy consisting of the intravenous administration of 0.75 mg of palonosetron, and 9.9 mg of dexamethasone and the oral administration of 125 mg of aprepitant on day 1, followed by the oral administration of 80 mg of aprepitant on days 2-3 and the oral administration of 8 mg of dexamethasone on days 2-4. The primary endpoint was the complete response rate (the CR rate; no vomiting and no rescue medication) during the overall phase (0-120 h). RESULTS: The efficacy analysis was performed in 63 patients. The CR rates during the overall, acute and delayed phases were 81.0, 96.8, and 81.0%, respectively. The no nausea and no significant nausea rate during the overall phase were 54.0 and 66.7%, respectively. The most common adverse event was grade 1 or 2 constipation. CONCLUSIONS: Triplet antiemetic therapy using a 0.75-mg dose of palonosetron shows a promising antiemetic effect in preventing CINV in lung cancer patients receiving HEC.

[A case of IgG4-related disease with marked thickening of the bronchial wall].

A 52-year-old man noticed hardening and swelling of his salivary glands in the summer of 2009. We suspected Mikulicz disease and performed several work-ups. His serum IgG4 level was elevated, and a chest computed tomography scan demonstrated marked thickening of the bronchial wall. A histopathologic examination of a bronchial mucosa biopsy specimen revealed diffuse infiltration of IgG4-positive cells in the submucosal layers, and on this basis we diagnosed IgG4-related disease. After the administration of corticosteroids, the patient's symptoms, his serum IgG4 level and bronchial wall thickening all improved. When encountering a patient with thickening of the bronchial wall, IgG4-related disease should be considered.

[A case of primary effusion lymphoma effectively treated by oral corticosteroid therapy].

Primary effusion lymphoma is a rare type of lymphoma which is confined to those body cavities associated with human herpes virus 8 infection in its development. We describe a 93-year-old man with primary effusion lymphoma in the pleura, but who was negative for herpes virus 8 infection. Chest computed tomography revealed bilateral pleural effusion, but did not show any evidence of a tumor mass or lymph node enlargement. Cytological analysis of his pleural effusion revealed atypical lymphoid cells with immunophenotypes which were positive for CD10, CD19 and CD20. Clonal rearrangement of the immunoglobulin-heavy chain gene was detected by Southern blot analysis, and a diagnosis of primary effusion lymphoma was made. Although dyspnea and severe hypoxia developed, accompanied with increased pleural effusion, chemotherapy was not indicated because of his age. We thus tried oral corticosteroid therapy for palliation which resulted in a dramatic, long-term decrease of his pleural effusion. We present a rare case of primary effusion lymphoma effectively controlled by corticosteroid therapy.

[Chronic intestinal pseudo-obstruction as a paraneoplastic presentation of limited-stage small cell lung cancer].

A 53-year-old woman with chief complaints of vomiting and constipation was given a diagnosis of ileus and admitted to a local hospital. The origin of the ileus was unknown despite intensive examinations. However, her chest X-ray film and CT showed left hilar and mediastinal lymphadenopathy. Her pro-gastrin-releasing peptide (ProGRP) levels were elevated. After transfer to our hospital, the diagnosis of small cell lung cancer (SCLC) was confirmed by transbronchial aspiration cytology. Since no cause of ileus was found on laparotomy, her symptoms were considered to indicate chronic intestinal pseudo-obstruction (CIPO), a manifestation of paraneoplastic neurological syndrome. Serum anti-Hu antibody testing was positive. Chemoradiotherapy induced complete remission and her abdominal symptoms markedly improved. This is a very rare case of CIPO accompanied with SCLC, which improved after immediate anti-tumor therapy for lung cancer.

Human T-cell leukemia virus type 1 Tax induces an aberrant clustering of the tumor suppressor Scribble through the PDZ domain-binding motif dependent and independent interaction.

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia. HTLV-1 Tax1 transforming protein interacts with several PDZ domain-containing proteins, and the interaction is associated with the transforming activities of Tax1 as well as persistent HTLV-1 infection. In this study, we show that Tax1 interacts with the tumor suppressor Scribble containing PDZ domains. Unlike other Tax1-interacting PDZ domain proteins, the PDZ domain-binding motif (PBM) of Tax1 was not required for the interaction with transiently expressed Scribble in 293T cells, but it was essential for the interaction with endogenous Scribble. Endogenous Scribble in 293T cells was primarily localized at the plasma membrane and colocalized with Tax1 but not Tax1C lacking PBM, whereas transiently expressed Scribble was localized in the cytoplasm and colocalized with Tax1C as well as Tax1, thus suggesting that Tax1 is recruited to the site of endogenous Scribble, such as the plasma membrane, in a PBM-dependent manner, and thereafter it interacts with Scribble in a PBM-independent and PBM-dependent manner. Endogenous Scribble was diffusely localized at the plasma membrane of HTLV-1-uninfected T-cell lines, whereas it colocalized with Tax1 as small and large aggregate at the plasma membranes. These results suggest that Tax1 through two binding sites induce aberrant clustering of Scribble, thereby altering the functions in HTLV-1-infected cells, which may thus play a role in persistent HTLV-1 infection and the pathogenesis.