Advancements in minimal residual disease detection: a practical approach using single-cell droplet PCR for comprehensive monitoring in hematological malignancy.

The identification of chromosomal abnormalities accompanied by copy number alterations is important for understanding tumor characteristics. Testing methodologies for copy number abnormality have limited sensitivity, resulting in their use only for the sample provided at the time of diagnosis or recurrence of malignancy, but not for the monitoring of minimal residual disease (MRD) during and after therapy. We developped the "DimShift" technology which enable to measure the copy number of target gene/chromosome in each cell, which is given by the single cell droplet PCR. Qualitative result of DimShift given by peripheral blood was perfectly concordant with that of bone marrow. These findings and performances are promising to be the new methodology for MRD detection in malignant diseases utilizing bone marrow as well as peripheral blood.

A Novel Method for Acquired Sex Chromosome Mosaicism.

The phenomenon of sex chromosome loss from hematopoietic cells is an emerging indicator of biological aging. While many methods to detect this loss have been developed, enhancing the field, these existing methods often suffer from being labor-intensive, expensive, and not sufficiently sensitive. To bridge this gap, a novel and more efficient technique is developed, named the SinChro assay. This method employs multiplexed single-cell droplet PCR, designed to detect cells with sex chromosome loss at single-cell resolution. Through the SinChro assay, the age-dependent increase in Y chromosome loss in male blood is successfully mapped. The age-dependent loss of the X chromosome in female blood is also identified, a finding that has been challenging with existing methods. The advent of the SinChro assay marks a significant breakthrough in the study of age-related sex mosaicism. Its utility extends beyond blood analysis, applicable to a variety of tissues, and it holds the potential to deepen the understanding of biological aging and related diseases.

Pulmonary Metastasectomy after Radiofrequency Ablation of Hepatocellular Carcinoma.

Introduction: Single distant metastases after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) are rare. There are no guidelines for treating patients without liver tumors after resecting lung metastases. Case Presentation: Here, we report a patient with HCC recurring as a single lung metastasis 14 months after RFA. A 76-year-old woman with primary biliary cholangitis without hepatitis B virus or hepatitis C virus infection had been treated by RFA for a single 16-mm-sized HCC lesion in liver S8. Fourteen months thereafter, despite lack of intrahepatic recurrence, a single new 26-mm-sized mass was found in S10 of the right lung. The patient underwent right lower lobectomy. The histopathological diagnosis was HCC metastasis. Because no residual disease could be found, she was followed up without any additional treatment after surgery. She remains alive with no signs of recurrence 3 years later. Conclusion: HCC patients who relapse with lung metastases but without intrahepatic recurrence after RFA are extremely rare, especially when RFA is used to treat HCC lesions <30 mm. However, it should be noted that, although rare, HCC may recur in the form of extrahepatic metastases after RFA. Furthermore, it is suggested that, as in the presently-described case, at least some patients without intrahepatic recurrence whose lung metastases are completely resected have a good prognosis even without additional treatment for HCC.

Gap junction beta-4 accelerates cell cycle progression and metastasis through MET-AKT activation in pancreatic cancer.

Despite continuing advances in the development of effective new therapies, including immunotherapies, the prognosis of pancreatic cancer remains extremely poor. Gap junction proteins have become attractive targets for potential cancer therapy. However, the role of gap junction beta-4 (GJB4) protein remains unexplored in pancreatic cancer. Through bioinformatic analyses we discovered pancreatic cancer tissues showed higher levels of GJB4 transcripts compared to normal pancreatic tissues and this had a negative effect on overall survival in patients that had pancreatic cancer. The high expression of nuclear GJB4 was identified as a negative prognostic factor in such patients. Knockdown of GJB4 in cultured pancreatic cancer cells resulted in G0/G1 arrest followed by decreased cell proliferation and suppression of metastatic potential. The overexpression of GJB4 accelerated cell proliferation, migration, and invasion in a SUIT-2 cell line, whereas MET inhibitor canceled the acceleration. GJB4 suppression with siRNA significantly inhibited tumor growth in a mouse xenograft model. Mechanistically, suppression of GJB4 inhibited MET-AKT activities. Such data suggest that targeting the GJB4-MET axis could represent a promising new therapeutic strategy for pancreatic cancer.

Clinical characterization of patients with gBRCA1/2 mutation-positive unresectable pancreatic cancer: a multicenter prospective study.

BACKGROUND: Accumulating evidence has demonstrated platinum-based chemotherapy followed by maintenance therapy with a poly Adenosine diphosphate (ADP)-ribose polymerase inhibitor (olaparib) show benefits in unresectable pancreatic cancer with a germline (g)BRCA1/2 mutation. Evaluation of the germline BRCA1 and BRCA2 mutation is essential for making decisions on a treatment strategy for patients with unresectable pancreatic cancer. However, the detection rates of germline BRCA1 and BRCA2 mutations and efficacy of maintenance with olaparib remain undetermined, prospectively, in Japan. METHODS & RESULTS: In this prospective analysis, the rate of germline BRCA1 and BRCA2 mutations and efficacy of chemotherapy were analyzed in 136 patients with pancreatic cancer who underwent BRACAnalysis® (85 patients) or FoundationOne® CDx (51 patients) between January 2020 and July 2022. A total of six patients (4.4%) had a germline BRCA1 and BRCA2 mutation. Five patients were treated with modified FOLFIRINOX and one with fluorouracil and oxaliplatin. All patients continued platinum-based chemotherapy for ˃4 months and were subsequently treated with olaparib as a maintenance therapy. The response rate to platinum-based chemotherapy in the germline BRCA1 and BRCA2 mutation-positive group was significantly better than that of the germline BRCA1 and BRCA2 mutation-negative group (66% vs 23%, P = 0.04). All patients harbouring a germline BRCA1 and BRCA2 mutation were able to switch to olaparib. The median progression-free survival using olaparib was 5.7 months (range 3.0-9.2). CONCLUSIONS: The rate of germline BRCA1 and BRCA2 mutations found in patients with unresectable pancreatic cancer was comparable to those of previous studies.An analysis of germline BRCA1 and BRCA2 mutations has benefits for all patients with unresectable pancreatic cancer with regard to decisions on therapeutic strategies in a clinical practice setting.

LMNA::NTRK1 Fusion-positive Leiomyosarcoma: Discrepancy between DNA-based Comprehensive Genomic Profiling and RNA Sequencing.

A 26-year-old man presented with a tumor in the left soleus muscle. The tumor was diagnosed as a locally advanced leiomyosarcoma. The patient was treated with irradiation followed by wide resection. One year after surgery, the patient presented with multiple lung metastases. Despite aggressive sequential chemotherapy, systemic metastatic tumors continued to develop. To explore therapeutic options for the patient, we performed DNA-based CGP with FoundationOne® CDx (F1). F1 identified anout-of-strand rearrangement of the NOS1AP::NTRK1 gene, which has not been previously reported. In contrast, RNA sequencing revealed an in-frame LMNA::NTRK1 gene, which is an oncogenic fusion gene.

Pemphigus vulgaris as an immune-related adverse event in recurrent metastatic esophageal squamous cell carcinoma treated with ipilimumab plus nivolumab: a case report and literature review.

Ipilimumab plus nivolumab therapy is approved for patients with unresectable advanced esophageal squamous cell carcinoma (ESCC). Although a combination of immune checkpoint inhibitors (ICIs), compared to conventional chemotherapy, can improve overall survival in patients with advanced ESCC, this increases the incidence of immune-related adverse events (irAEs). Here, we describe an ESCC case that developed pemphigus vulgaris (PV), an extremely rare cutaneous irAE, during ipilimumab plus nivolumab treatment. The patient achieved a partial response to treatment. The PV was successfully managed after the cessation of ipilimumab and the use of a topical steroid. We should thus re-treat ESCC with nivolumab monotherapy. In the era of ICIs as standard cancer therapeutics, diagnostic criteria for blistering diseases need to be established to properly manage patients with cutaneous irAEs.

Synergistic antitumor effect of histone deacetylase class IIa inhibitor with lenvatinib in hepatocellular carcinoma.

BACKGROUND: Histone deacetylase (HDAC) class I and IIa are highly expressed in hepatocellular carcinoma (HCC) and associated with decreased survival. However, clinically used pan and class I inhibitors have serious adverse events. In this study, we assessed the antitumor effects and tolerability of class IIa HDAC inhibitor (HDACI) with lenvatinib, which is a standard therapy for HCC. METHODS AND RESULT: Combination therapy with class IIa HDACI and lenvatinib exerted synergistic antitumor effect in human HCC cell lines. In mouse models, this therapy showed significant antitumor effects, and few adverse events occurred. In immunoblotting, the expression of fibroblast growth factor receptor 4 (FGFR4) and fibroblast growth factor 19 (FGF19) was high in cell lines that showed a high antitumor effect. In addition, class IIa HDACI administration decreased the expression of FGFR4. In the small interfering RNA (siRNA) analysis, knockdown of HDAC9, which is an isoform of HDAC class IIa, reduced the expression of FGFR4 and induced apoptosis. Immunohistochemistry of human clinical specimens showed a positivity rate of 32% for FGFR4 and 84% for HDAC9 in HCC, and all FGFR4-positive patients were HDAC9 positive. CONCLUSION: Class IIa HDACI and lenvatinib combination therapy induces apoptosis by downregulating FGFR4 and blocking the FGFR signaling in FGFR4-positive HCC cell lines and has demonstrated synergistic antitumor effects and safety. This combination therapy overcomes the problems of conventional therapies and will be beneficial for FGFR4-positive HCC patients.

Achievement of a durable response with eribulin for relapsed cardiac metastasis of uterine leiomyosarcoma after surgery: a case report and literature review.

BACKGROUND: Uterine leiomyosarcoma (U-LMS) is an aggressive malignancy linked to a high risk of metastasis to distant major organs. Although cardiac metastasis of U-LMS is extremely rare, it is often associated with life-threatening conditions, leading to dismal prognosis. Currently, there is no established therapy for patients with unresectable/relapsed cardiac metastasis of U-LMS. In this article, we report a case of locally relapsed cardiac metastasis of U-LMS, which occurred 3 years after surgical resection, successfully treated with eribulin. CASE DESCRIPTION: A 69-year-old female with cardiac symptoms (e.g., dyspnea, tachycardia, and easy fatigability) was sequentially treated with doxorubicin plus ifosfamide, gemcitabine plus docetaxel, and pazopanib. However, cardiac metastasis continued to grow despite treatment. Hence, eribulin was administered as fourth-line therapy. Exceptionally, eribulin markedly improved cardiac symptoms, and the patient achieved a durable response for 17 months without the development of severe adverse events. Moreover, the volume of the metastatic cardiac tumor was decreased by 70%. Despite the poor prognosis of this condition, the patient survived for 8 years from the diagnosis of cardiac metastasis due to surgery and the continuous administration of chemotherapies. CONCLUSIONS: Eribulin may be an effective and accessible treatment option for cardiac metastasis of U-LMS in patients with life-threatening conditions for whom surgery is not indicated. Additionally, the expression levels of phosphorylated AKT (p-AKT) may be a predictive biomarker for the sensitivity of patients with U-LMS to treatment with eribulin.

Effect of comprehensive cancer genomic profiling on therapeutic strategies and clinical outcomes in patients with advanced biliary tract cancer: A prospective multicenter study.

Characterization of the genomic landscape of biliary tract cancer (BTC) may lead to applying genotype-matched therapy for patients with this disease. Evidence that comprehensive cancer genomic profiling (CGP) guides genotype-matched therapy to improve clinical outcomes is building. However, the significance of CGP in patients with BTC remains unclarified in clinical practice. Therefore, the purposes of this study were to assess the utility of CGP and identify associations between clinical outcomes and genomic alterations in patients with BTC. In this prospective analysis, detection rates for actionable genomic alterations and access rates for genotype-matched therapy were analyzed in 72 patients with advanced BTC who had undergone commercial CGP. Cox regression analyses assessed relationships between overall survival and genomic alterations detected with CGP. The most common genomic alterations detected were TP53 (41, 56.9%), followed by CDKN2A/B (24, 33.3%/20, 27.8%), and KRAS (20, 27.8%). Actionable genomic alterations were identified in 58.3% (42/72) of patients. Detection rates for FGFR2 fusions, IDH1 mutations, and BRAF V600E were low in this cohort. Eight (11.1%) patients received genotype-matched therapy. For patients with intrahepatic cholangiocarcinoma (ICC), CDKN2A/B loss was associated with shorter overall survival. These real-world data demonstrate that CGP can identify therapeutic options in patients with advanced BTC. CDKN2A/B loss was identified as a poor prognostic factor in patients with ICC. Thus, this study provides a rationale for considering CGP in planning therapeutic strategies for advanced BTC.

Association between Hepatic Oxidative Stress Related Factors and Activation of Wnt/ß-Catenin Signaling in NAFLD-Induced Hepatocellular Carcinoma.

We investigated the association between iron overload, oxidative stress (8-oxo-7,8-dihydroguanine: 8-oxo-dG scores), Wnt/ß-catenin pathway activation (expression of glutamine synthetase: GS), and tumor hyperintensity in the Gd-EOB-DTPA-enhanced MRI hepatobiliary phase (relative enhancement ratio: RER). This was a retrospective analysis of 94 hepatocellular carcinoma (HCC) patients who underwent surgical resection. In HBV-, HCV-, and alcohol-associated HCC, serum ferritin levels in the high and low RER groups were equivalent. In contrast, ferritin levels were elevated in the 'high RER' group of patients with nonalcoholic fatty liver disease (NAFLD)-HCC. As predictors of GS positivity, high RER had a sensitivity of 57.2% and a specificity of 100%. High serum ferritin had a sensitivity of 85.7% and a specificity of 85.7%. All cases with serum ferritin ≥275.5 ng/mL and high RER were 8-oxo-dG- and iron staining-positive. Additionally, GS positivity was seen in all cases with "serum ferritin levels above the upper limits or iron staining-positive" and '8-oxo-dG high' cases. Therefore, combining serum ferritin levels with RER may increase the accuracy with which activated Wnt/ß-catenin signaling is predicted in NAFLD-HCC. We suggest that 8-oxo-dG accumulates following increased oxidative stress due to hepatic tissue iron deposition; this may activate Wnt/ß-catenin signaling and trigger carcinogenesis.

Two cases of resected gallbladder carcinosarcoma with a contrasting course.

INTRODUCTION: Carcinosarcoma of the gallbladder is a rare tumor with both carcinoma and sarcoma components. CASE PRESENTATION: In this paper, we report two cases. The first case is of a man in his 60s who was preoperatively diagnosed with gallbladder carcinosarcoma and has achieved 6 years and 6 months survival through aggressive surgical treatment. The second case is of a woman in her 70s who was diagnosed with locally advanced gallbladder cancer; she underwent multidisciplinary treatment for the same, but died 8 months after the surgery. While the primary disorder was the same in both cases, the clinical courses contrasted sharply. DISCUSSION: There is no established chemotherapy or radiation therapy for gallbladder carcinosarcoma, and the only curative treatment is surgery. However, it has a very poor prognosis. CONCLUSION: Carcinosarcoma of the gallbladder may progress very rapidly, and the treatment management should be carefully decided.

Combination of psoas muscle mass index and neutrophil/lymphocyte ratio as a prognostic predictor for patients undergoing nonsurgical hepatocellular carcinoma therapy.

BACKGROUND AND AIM: Reliable predictors for hepatocellular carcinoma (HCC) are urgently needed. The psoas muscle index (PMI) is a simple and rapid method for evaluating muscle atrophy. Furthermore, the neutrophil/lymphocyte ratio (NLR) is a prognostic factor that is easy to calculate in everyday clinical practice. We aimed to investigate the value of the PMI and NLR as prognostic factors for patients receiving nonsurgical HCC therapy, hepatic arterial infusion chemotherapy (HAIC), transcatheter arterial chemoembolization (TACE), or molecular targeted drugs such as sorafenib (SOR) and lenvatinib (LEN). METHODS: We enrolled 87 patients with HCC who were treated with HAIC, TACE, SOR, or LEN. The primary endpoint was overall survival (OS) with variable PMI or NLR status. For Barcelona Clinic Liver Cancer (BCLC)-B patients, useful prognostic factors were examined by comparing the OS between stratified groups. Prognostic factors including PMI and NLR were evaluated by univariate and multivariate analysis. RESULTS: Analysis of HAIC or TACE (HAIC/TACE) and SOR or LEN (SOR/LEN) patients showed significant differences in OS between low and high PMI. In patients treated with TACE, there was a significant difference in OS between low and high NLR. For BCLC-B and low PMI, the prognosis was significantly worse for SOR/LEN than for TACE, although there was no difference for high PMI, suggesting that PMI may be useful for treatment selection. In addition, the prognostic formula composed of PMI, NLR, and up-to-seven criteria developed in the present study may be useful. CONCLUSION: PMI and NLR are considered to be independent prognostic factors for HCC.

[A case of intraductal tubulopapillary adenocarcinoma with bone metastases].

A woman in her 70s with main pancreatic duct dilatation was referred to our hospital. Various imaging examinations showed an extensive mass within the lumen of the main pancreatic duct in the head and body of the pancreas. The microscopic examination of a biopsy specimen revealed an adenocarcinoma. She was diagnosed with intraductal tubulopapillary adenocarcinoma of the pancreas;a pylorus-preserving total pancreatectomy was subsequently performed. However, 30 days after surgery, the patient presented with neck pain and left upper arm numbness. Results of magnetic resonance imaging and bone scintigraphy revealed a cervical spinal tumor that was subsequently biopsied. The patient was diagnosed with intraductal tubulopapillary adenocarcinoma with bone metastasis.

Six-transmembrane epithelial antigen of the prostate 1 accelerates cell proliferation by targeting c-Myc in liver cancer cells.

Six-transmembrane epithelial antigen of the prostate 1 (STEAP1) has emerged as an ideal target in cancer therapeutics. However, the functions of STEAP1 in liver cancer remain unexplored. The current study aimed to characterize the biological roles of STEAP1 in liver cancer. STEAP1 expression was upregulated in tumor tissues, and high STEAP1 expression was associated with poor clinical outcomes in patients with liver cancer, according to several publicly available datasets. STEAP1 silencing using small interfering RNA inhibited cell proliferation and was accompanied by G1 arrest induced by the suppression of cyclin D1 and the promotion of p27. STEAP1 silencing suppressed c-Myc expression, which was identified as a component in STEAP1 signal transduction by mining publicly available datasets and was then confirmed by PCR array. In conclusion, the knockdown of STEAP1 in liver cancer cell lines led to inhibition of cell proliferation involving G1 arrest by suppressing c-Myc. The present study provides a preclinical concept for STEAP1 as a druggable target in liver cancer.

MUTYH is associated with hepatocarcinogenesis in a non-alcoholic steatohepatitis mouse model.

Non-alcoholic steatohepatitis (NASH)-related HCC is associated with oxidative stress. However, the mechanisms underlying the development of NASH-related HCC is unclear. MUTYH is one of the enzymes that is involved in repair of oxidative DNA damage. The aim of this study was to investigate the association between MUTYH and NASH-related hepatocarcinogenesis. MUTYH wild-type (Mutyh+/+), heterozygous (Mutyh+/-), and MUTYH-null (Mutyh-/-) mice were fed a high-fat high-cholesterol (HFHC) diet or HFHC + high iron diet (20 mice per group) for 9 months. Five of 20 Mutyh-/- mice fed an HFHC + high iron diet developed liver tumors, and they developed more liver tumors than other groups (especially vs. Mutyh+/+ fed an HFHC diet, P = 0.0168). Immunohistochemical analysis revealed significantly higher accumulation of oxidative stress markers in mice fed an HFHC + high iron diet. The gene expression profiles in the non-tumorous hepatic tissues were compared between wild-type mice that developed no liver tumors and MUTYH-null mice that developed liver tumors. Gene Set Enrichment Analysis identified the involvement of the Wnt/ß-catenin signaling pathway and increased expression of c-Myc in MUTYH-null liver. These findings suggest that MUTYH deficiency is associated with hepatocarcinogenesis in patients with NASH with hepatic iron accumulation.

Impaired T- and NK-cell reconstitution after haploidentical HCT with posttransplant cyclophosphamide.

Administration of posttransplant cyclophosphamide (PTCy) has significantly expanded the number of patients undergoing HLA-haploidentical hematopoietic cell transplantation (haplo-HCT). To examine immune reconstitution in these patients, we monitored T- and natural killer (NK)-cell recovery in 60 patients receiving bone marrow or peripheral blood stem cell (PBSC) grafts after haplo-HCT with PTCy and 35 patients receiving HLA-matched donor PBSC grafts with standard graft-versus-host disease (GVHD) prophylaxis. Compared with HLA-matched recipients, early T-cell recovery was delayed in haplo-HCT patients and skewed toward effector memory T cells with markedly reduced naive T cells. We found higher regulatory T (Treg)-cell/conventional T (Tcon)-cell ratios early after HCT and increased PD-1 expression on memory T cells. Within the haplo-HCT, patients who did not develop chronic GVHD (cGVHD) had higher PD-1 expression on central and effector memory CD4+ Treg cells at 1 month after transplant. These findings suggest an immunologic milieu that promotes immune tolerance in haplo-HCT patients. NK cells were decreased early after haplo-HCT with preferential expansion of immature CD56brightCD16- NK cells compared with matched donor transplants. One month after transplant, mass cytometry revealed enrichment of immature NK-cell metaclusters with high NKG2A, low CD57, and low killer-cell immunoglobulin-like receptor expression after haplo-HCT, which partially recovered 3 months post-HCT. At 2 months, immature NK cells from both groups were functionally impaired, but interleukin-15 priming corrected these defects in vitro. Increased immature/mature NK-cell ratios were associated with cytomegalovirus reactivation and increased incidence of cGVHD after haplo-HCT. These homeostatic imbalances in T- and NK-cell reconstitution after haplo-HCT reveal opportunities for early immune-based interventions to optimize clinical outcomes.

Rare case of acinar cell carcinoma with multiple lesions in the pancreas.

We present the first case of pancreatic acinar cell carcinoma (PACC) with multiple lesions. A 55-year-old man with a pancretic tail mass on abdominal computed tomography (CT) was admitted to our hospital. Endoscopic ultrasound (EUS) showed a hypoechoic mass, and EUS-guided fine-needle aspiration (EUS-FNA) revealed the mass to be PACC. The patient underwent distal pancreatectomy, and two masses were identified in the pancreatic tail and body. Histologically, both masses had tumor cells similar to acinar cells and were positive for BCL-10. The patient was thus diagnosed with synchronous PACC. Ten months after the surgery, abdominal CT revealed a mass in the remnant pancreas. EUS showed a hypoechoic mass, and EUS-FNA determined it to be PACC. The patient underwent total remnant pancreatectomy. The histological imaging results were similar to those of the first resection. Finally, the patient was diagnosed with synchronous and metachronous PACC. The possibility of multiple occurrences in the pancreas should be considered with PACC.

Pancreatic cancer with leptomeningeal carcinomatosis: case report and literature review.

Leptomeningeal carcinomatosis (LMC) associated with pancreatic cancer is an extremely rare complication. Symptoms vary depending on the site of invasion and include intracranial pressure, and cranial and spinal dysfunction making early diagnosis difficult. We describe a rare case of leptomeningeal metastasis from pancreatic cancer. A 59-year-old man was diagnosed with unresectable pancreatic cancer and subsequently received systemic chemotherapy. Initial chemotherapy was effective. After 12 months the patient's serum carbohydrate antigen (CA)19-9 level had become elevated, and he presented with neck and back pain, and shoulder stiffness. Tumor enlargement was not detected by computed tomography (CT) and positron emission tomography-CT. Contrast CT of the brain revealed evidence of leptomeningeal enhancement. Cerebrospinal fluid cytology showed atypical, but not malignant cells; the CA19-9 level was further elevated. The patient was finally diagnosed with LMC and, being in poor general condition, received palliative care. During the treatment of pancreatic cancer, the potential existence of LMC should be contemplated when a serum tumor marker becomes rapidly elevated despite the control of primary or metastatic sites.

BH3 profiling discriminates the anti­apoptotic status of 5­fluorouracil­resistant colon cancer cells.

5­Fluorouracil (5­FU) is a cytotoxic anticancer drug commonly used for patients with advanced colon cancer. This drug effectively reduces the size of tumors to a certain degree; however, cancer cells can gradually acquire resistance, resulting in disease progression. To identify the mechanism of 5­FU resistance, we established three 5­FU­resistant colon cancer cell lines and analyzed both apoptosis­related protein expression levels and BH3 profiling. These 5­FU­resistant colon cancer cell lines acquired apoptotic resistance to 5­FU. Although apoptosis­related protein expression levels were altered in each 5­FU­resistant colon cancer cell line variably, BH3 profiling indicated BCLXL dependence in 5­FU­resistant HT­29 cells only. Functional BCLXL inhibition in 5­FU­resistant HT­29 cells not only sensitized the cells to apoptosis but also overcame 5­FU resistance. The apoptotic BIM protein was preferentially sequestered, thereby resulting in acquired dependence on BCLXL for survival. Additionally, in vivo models showed that BCLXL inhibition controlled tumor progression. These results indicate that BH3 profiling facilitates the identification of the functional role of anti­apoptotic proteins during drug resistance and has clinical implications for colon cancer in targeting specific proteins such as BCLXL.