Phase 2 study of treatment selection based on tumor thymidylate synthase expression in previously untreated patients with metastatic colorectal cancer: A trial of the ECOG-ACRIN Cancer Research Group (E4203).

BACKGROUND: The authors hypothesized that patients with metastatic colorectal cancer (mCRC) who had tumors with low thymidylate synthase (TS-L) expression would have a higher response rate to combined 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) plus bevacizumab (FOLFOX/Bev) than those with high TS (TS-H) expression and that combined irinotecan and oxaliplatin (IROX) plus bevacizumab (IROX/Bev) would be more effective than FOLFOX/Bev in those with TS-H tumors. METHODS: TS protein expression was determined in mCRC tissue. Patients who had TS-L tumors received FOLFOX/Bev, and those who had TS-H tumors were randomly assigned to receive either FOLFOX/Bev or IROX/Bev. The primary endpoint was the response rate (complete plus partial responses). RESULTS: In total, 211 of 247 patients (70% TS-H) were registered to the treatment phase. Efficacy analyses included eligible patients who had started treatment (N = 186). The response rates for patients who received IROX/Bev (TS-H), FOLFOX/Bev (TS-H), and FOLFOX/Bev (TS-L) were 33%, 38%, and 49%, respectively (P = nonsignificant). The median progression-free survival (PFS) was 10 months (95% confidence interval [CI], 9-12 months; 10 months in the IROX/Bev TS-H group, 9 months in the FOLFOX/Bev TS-H group, and 13 months in the FOLFOX/Bev TS-L group). The TS-L group had improved PFS compared with the TS-H group that received FOLFOX/Bev (hazard ratio, 1.6; 95% CI, 1.0%-2.4%; P = .04; Cox regression). The median overall survival (OS) was 22 months (95% CI, 20 29 months; 18 months in the IROX/Bev TS-H group, 21 months in the FOLFOX/Bev TS-H group, and 32 months in the TS-L group). OS comparisons for the 2 TS-H arms and for the FOLFOX/Bev TS-H versus TS-L arms were not significantly different. CONCLUSIONS: TS expression was prognostic: Patients with TS-L tumors who received FOLFOX/Bev had a longer PFS than those with TS-H tumors, along with a trend toward longer OS. Patients with TS-H tumors did not benefit more from IROX/Bev than from FOLFOX/Bev. Cancer 2018;124:688-97. © 2017 American Cancer Society.

Exploring Metabolic Profile Differences between Colorectal Polyp Patients and Controls Using Seemingly Unrelated Regression.

Despite the fact that colorectal cancer (CRC) is one of the most prevalent and deadly cancers in the world, the development of improved and robust biomarkers to enable screening, surveillance, and therapy monitoring of CRC continues to be evasive. In particular, patients with colon polyps are at higher risk of developing colon cancer; however, noninvasive methods to identify these patients suffer from poor performance. In consideration of the challenges involved in identifying metabolite biomarkers in individuals with high risk for colon cancer, we have investigated NMR-based metabolite profiling in combination with numerous demographic parameters to investigate the ability of serum metabolites to differentiate polyp patients from healthy subjects. We also investigated the effect of disease risk on different groups of biologically related metabolites. A powerful statistical approach, seemingly unrelated regression (SUR), was used to model the correlated levels of metabolites in the same biological group. The metabolites were found to be significantly affected by demographic covariates such as gender, BMI, BMI(2), and smoking status. After accounting for the effects of the confounding factors, we then investigated potential of metabolites from serum to differentiate patients with polyps and age matched healthy controls. Our results showed that while only valine was slightly associated, individually, with polyp patients, a number of biologically related groups of metabolites were significantly associated with polyps. These results may explain some of the challenges and promise a novel avenue for future metabolite profiling methodologies.

Elevated phospholipase A2 activities in plasma samples from multiple cancers.

Only in recent years have phospholipase A2 enzymes (PLA2s) emerged as cancer targets. In this work, we report the first detection of elevated PLA2 activities in plasma from patients with colorectal, lung, pancreatic, and bladder cancers as compared to healthy controls. Independent sets of clinical plasma samples were obtained from two different sites. The first set was from patients with colorectal cancer (CRC; n = 38) and healthy controls (n = 77). The second set was from patients with lung (n = 95), bladder (n = 31), or pancreatic cancers (n = 38), and healthy controls (n = 79). PLA2 activities were analyzed by a validated quantitative fluorescent assay method and subtype PLA2 activities were defined in the presence of selective inhibitors. The natural PLA2 activity, as well as each subtype of PLA2 activity was elevated in each cancer group as compared to healthy controls. PLA2 activities were increased in late stage vs. early stage cases in CRC. PLA2 activities were not influenced by sex, smoking, alcohol consumption, or body-mass index (BMI). Samples from the two independent sites confirmed the results. Plasma PLA2 activities had approximately 70% specificity and sensitivity to detect cancer. The marker and targeting values of PLA2 activity have been suggested.

Plk1 phosphorylation of orc2 and hbo1 contributes to gemcitabine resistance in pancreatic cancer.

Although gemcitabine is the standard chemotherapeutic drug for treatment of pancreatic cancer, almost all patients eventually develop resistance to this agent. Previous studies identified Polo-like kinase 1 (Plk1) as the mediator of gemcitabine resistance, but the molecular mechanism remains unknown. In this study, we show that Plk1 phosphorylation of Orc2 and Hbo1 mediates the resistance to gemcitabine. We show that the level of Plk1 expression positively correlates with gemcitabine resistance, both in pancreatic cancer cells and xenograft tumors. Overexpression of Plk1 increases gemcitabine resistance, while inhibition of Plk1 sensitizes pancreatic cancer cells to gemcitabine treatment. To validate our findings, we show that inhibition of Plk1 sensitizes tumors to gemcitabine treatment in a mouse xenograft study. Mechanistically, we find that Plk1 phosphorylation of Orc2 maintains DNA replication on gemcitabine treatment. Furthermore, Plk1 phosphorylation of Hbo1 transcriptionally increases cFos expression and consequently elevates its target multidrug resistance 1 (MDR1), which was previously reported to confer chemotherapeutic drug resistance. Knockdown of cFos or MDR1 sensitizes gemcitabine-resistant cells to gemcitabine treatment. Finally, pancreatic cancer cells expressing Plk1-unphosphorylatable mutants of Orc2 or Hbo1 are more sensitive to gemcitabine than cells expressing wild-type Orc2 or Hbo1. In short, our study provides a mechanism for Plk1-mediated gemcitabine resistance, suggesting that Plk1 is a promising target for treatment of gemcitabine-resistant pancreatic cancer.

Phase I study of bosutinib, a src/abl tyrosine kinase inhibitor, administered to patients with advanced solid tumors.

PURPOSE: Bosutinib, a potent ATP-competitive, quinolinecarbonitrile Src/Abl kinase inhibitor, was tested in this first-in-human phase I trial in patients with advanced solid tumor malignancies. PATIENTS AND METHODS: This trial was conducted in 2 parts. In part 1 (dose escalation), increasing oral bosutinib doses were administered using a 3 + 3 design. In part 2 (dose expansion), approximately 30 patients each with refractory colorectal, pancreas, or non-small cell lung cancer were treated at the recommended phase II dose (RP2D). Primary efficacy endpoints for part 2 were median progression-free survival (colorectal and non-small cell lung) and median overall survival (pancreas). RESULTS: In part 1, dose-limiting toxicities of grade 3 diarrhea (two patients) and grade 3 rash occurred with bosutinib 600 mg/day and the maximum tolerated dose identified was 500 mg/day. However, the majority of patients treated with 500 mg/day had grade 2 or greater gastrointestinal toxicity, and 400 mg/day was identified as the RP2D. The most common bosutinib-related adverse events were nausea (60% patients), diarrhea (47%), vomiting (40%), fatigue (38%), and anorexia (36%). Bosutinib had a mean half-life of 19 to 20 hours at the RP2D. A partial response (breast) and unconfirmed complete response (pancreas) were observed; 8 of 112 evaluable patients had stable disease for 22 to 101 weeks. However, the primary efficacy endpoints for part 2 were not met. CONCLUSIONS: Bosutinib was generally well tolerated in patients with solid tumors, with the main toxicity being gastrointestinal. The RP2D was 400 mg/day orally. Further study of bosutinib is planned in combination regimens.

Retrospective analysis of satraplatin in patients with metastatic urothelial cancer refractory to standard platinum-based chemotherapy.

UNLABELLED: Satraplatin is a novel platinum agent with favorable clinical attributes including oral bioavailability and lack of significant treatment-associated neuropathy and nephropathy. Furthermore, preclinical studies have shown that satraplatin is active is cisplatin-resistant tumors. We retrospectively evaluated the activity of satraplatin in patients with cisplatin or carboplatin-refractory urothelial carcinoma and demonstrated lack of significant antitumor activity in this population. BACKGROUND: Satraplatin is an oral platinum analogue with antitumor activity in cisplatin-resistant cells lines. The activity of satraplatin in patients with metastatic cancers of the urothelial tract refractory to standard platinum agents has not previously been reported. METHODS: We previously reported a phase I study of the safety and pharmacokinetics of satraplatin in patients with refractory solid tumors and varying degrees of renal impairment. Given that the majority of patients enrolled in the study had metastatic cancers of the urothelial tract, and all patients were treated with a uniform dose and schedule, we performed a retrospective analysis to describe the activity of satraplatin in this cohort. RESULTS: A total of 12 patients with metastatic cancers of the urothelial tract were enrolled. The majority (83%) had transitional cell carcinomas, whereas 2 patients (17%) had adenocarcinomas. All patients were treated previously with platinum agents; 6 patients (50%) had previously received cisplatin and 8 patients (67%) had previously received carboplatin. Patients were treated with a median of 1.5 cycles of satraplatin (range, 1-4). There were no objective responses; 1/12 (8%) patients experienced transient stable disease and 11/12 (92%) experienced disease progression as best response. CONCLUSIONS: Treatment with satraplatin in patients with metastatic cancers of the urothelial tract who had progressed on standard platinum-based chemotherapy resulted in negligible antitumor activity. These conclusions are limited by the retrospective nature of the analysis and the phase I population from which the data were derived. The activity of satraplatin in patients with metastatic cancers of the urothelial tract who have been less heavily pretreated is unknown.

CD40 agonists alter tumor stroma and show efficacy against pancreatic carcinoma in mice and humans.

Immunosuppressive tumor microenvironments can restrain antitumor immunity, particularly in pancreatic ductal adenocarcinoma (PDA). Because CD40 activation can reverse immune suppression and drive antitumor T cell responses, we tested the combination of an agonist CD40 antibody with gemcitabine chemotherapy in a small cohort of patients with surgically incurable PDA and observed tumor regressions in some patients. We reproduced this treatment effect in a genetically engineered mouse model of PDA and found unexpectedly that tumor regression required macrophages but not T cells or gemcitabine. CD40-activated macrophages rapidly infiltrated tumors, became tumoricidal, and facilitated the depletion of tumor stroma. Thus, cancer immune surveillance does not necessarily depend on therapy-induced T cells; rather, our findings demonstrate a CD40-dependent mechanism for targeting tumor stroma in the treatment of cancer.

Phase I and pharmacokinetic study of CT-322 (BMS-844203), a targeted Adnectin inhibitor of VEGFR-2 based on a domain of human fibronectin.

PURPOSE: To determine the maximum tolerated dose (MTD), safety, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary antitumor activity of CT-322 (BMS-844203), a VEGFR-2 inhibitor and the first human fibronectin domain-based targeted biologic (Adnectin) to enter clinical studies. EXPERIMENTAL DESIGN: Patients with advanced solid malignancies were treated with escalating doses of CT-322 intravenously (i.v.) weekly (qw), or biweekly (q2w). Plasma samples were assayed for CT-322 concentrations, plasma VEGF-A concentrations, and antidrug antibodies. RESULTS: Thirty-nine patients completed 105 cycles of 0.1 to 3.0 mg/kg CT-322 i.v. either qw or q2w. The most common treatment-emergent grade 1/2 toxicities were fatigue, nausea, proteinuria, vomiting, anorexia, and hypertension. Grade 3/4 toxicities were rare. Reversible proteinuria, retinal artery, and vein thrombosis, left ventricular dysfunction, and reversible posterior leukoencephalopathy syndrome were dose limiting at 3.0 mg/kg. The MTD was 2 mg/kg qw or q2w. CT-322 plasma concentrations increased dose proportionally. Plasma VEGF-A levels increased with dose and plateaued at 2 mg/kg qw. Anti-CT-322 antibodies developed without effects on pharmacokinetics, VEGF-A levels, or safety. Minor decreases in tumor measurements occurred in 4 of 34 evaluable patients and 24 patients had stable disease. CONCLUSIONS: CT-322 can be safely administered at 2 mg/kg i.v. qw or q2w and exhibits promising antitumor activity in patients with advanced solid tumors. The absence of severe toxicities at the MTD, demonstration of plasma drug concentrations active in preclinical models, and clinical pharmacodynamic evidence of VEGFR-2 inhibition warrant further development of CT-322 and suggest strong potential for Adnectin-based targeted biologics.

A phase II study of gemcitabine in combination with radiation therapy in patients with localized, unresectable, pancreatic cancer: a Hoosier Oncology Group study.

OBJECTIVE: A Phase II study was conducted at Indiana University to evaluate the safety and efficacy of combined weekly Gemcitabine (GEM) with external beam radiotherapy (RT) in unresectable, locally advanced pancreatic cancer (LAPC). METHODS: Eligible patients had biopsy-proven LAPC without evidence of metastatic disease. In part A of the treatment plan, patients received GEM 600 mg/m(2) IV weekly, with concurrent RT (50.4 Gy in 28 fractions, 1.8 Gy/d, 5 days per week). Part B of the treatment plan began approximately 4 weeks after completing part A: patients without disease progression received weekly GEM 1000 mg/m(2) on days 1, 8, and 15 of a 28-day cycle for 6 cycles or until disease progression. RESULTS: From April 2001 to June 2003, of 28 patients evaluated, 24 (86%) completed part A. About 22 patients had grade 3 toxicities, primarily hematologic (43%) and gastrointestinal (36%). Three patients (11%) had grade 4 toxicities (one each for hyperbilirubinemia, infection, and dyspnea). The median follow-up was 10 months (1-63 months) for all enrolled patients. Six patients (21%) had a radiologic partial response, 16 (57%) had stable disease, 5 (18%) had progressive disease, and 1 patient (4%) had an unevaluable response at last follow-up. Four patients (14%) underwent surgical resection (2 with R0 resection). Median time to progression was 6 months (0-36 months). Median survival time was 10.3 months (95% confidence interval, 7.9-14.6 months). The 1- and 2-year actuarial survival rates were 30% and 11%. At last analysis, all but 2 patients died. CONCLUSION: The activity and toxicity profile of combination GEM and RT indicates that this can be safely administered for patients with LAPC.

Pancreatic cancer: utility of dynamic contrast-enhanced MR imaging in assessment of antiangiogenic therapy.

PURPOSE: To prospectively evaluate the utility of dynamic contrast material-enhanced magnetic resonance (MR) imaging in predicting the response of locally advanced pancreatic cancer to combined chemotherapy and antiangiogenic therapy. MATERIALS AND METHODS: This prospective, institutional review board-approved, HIPAA-compliant study with informed consent assessed dynamic contrast-enhanced MR imaging in 11 patients (mean age, 54.3 years; six men and five women) with locally invasive pancreatic cancer before and 28 days after combined chemotherapy and antiangiogenic therapy. Axial perfusion images were obtained after injection of 0.1 mmol gadopentetate dimeglumine per kilogram of body weight. Sagittal images of the upper abdominal aorta were obtained for arterial input function calculation. A two-compartment kinetic model was used to calculate the perfusion parameters K(trans) (the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space), K(ep) (the rate constant that represents transfer of contrast agent from the extravascular extracellular space to the blood plasma), and volume of distribution (v(e)). Semiquantitative measurements, peak tissue gadolinium concentration (C(peak)), maximum slope of gadolinium increase (slope), and area under the gadolinium curve at 60 seconds (AUC(60)) were also calculated. Perfusion parameters and tumor size changes were correlated with carbohydrate antigen 19-9 levels. Comparisons between pre- and posttreatment studies were performed by using the Wilcoxon signed rank test, and comparisons between responders and nonresponders were performed by using the Mann-Whitney test. RESULTS: After therapy, K(trans), v(e), C(peak), slope, and AUC(60) decreased significantly (P = .02, .001, .002, .007, and .01, respectively). Tumor size and K(ep) were not significantly changed. Pretreatment K(trans) and K(ep) were significantly higher (P = .02 and .006, respectively) in tumors that showed marker response than in those that did not. A pretreatment K(trans) value (milliliters of blood per milliliter of tissue times minutes) of more than 0.78 mL/mL . min was 100% sensitive and 71% specific for subsequent tumor response. Semiquantative parameters and tumor size were not different between the groups. CONCLUSION: Pretreatment K(trans) measurement in pancreatic tumors can predict response to antiangiogenic therapy. All perfusion parameters showed substantial reduction after 28 days of combined chemotherapy and antiangiogenic therapy.

A phase 2 trial of glufosfamide in combination with gemcitabine in chemotherapy-naive pancreatic adenocarcinoma.

OBJECTIVES: A dose-escalation study of glufosfamide plus gemcitabine showed that the combination could be administered safely at full doses. The purpose of this phase II study was to evaluate the safety and efficacy of this combination in chemotherapy-naive pancreatic adenocarcinoma. METHODS: Eligible patients had metastatic and/or locally advanced pancreatic adenocarcinoma, Karnofsky performance status >or=70, creatinine clearance (CrCL) >or=60 mL/min, and acceptable organ function. Patients received glufosfamide 4500 mg/m intravenous on day 1 and gemcitabine 1000 mg/m intravenous on Days 1, 8, and 15 of every 28-day cycle. The primary end point was response rate. RESULTS: Twenty-nine patients were enrolled; 14 male, median age 58 years. Twenty-three (79%) patients had distant metastases. Median cycles on treatment was 4 (range: 1-18+). Of 28, 5 (18%; 95% CI: 6%-37%) patients had a confirmed partial response (median duration: 8.4 months) and 1 had an unconfirmed partial response. Eleven patients (39%) had stable disease. Median progression-free survival was 3.7 months, median overall survival was 6 months, and 1-year survival was 32%. Grade 3/4 neutropenia occurred in 23 (79%) patients and grade 3/4 thrombocytopenia in 10 (34%) patients. The CrCL fell below 60 mL/min in 10 of 27 (37%) patients. Renal failure occurred in 4 patients. Decrease in CrCL was correlated with glufosfamide and isophosphoramide mustard pharmacokinetic area under the curve. CONCLUSIONS: The combination of glufosfamide plus gemcitabine is active in pancreatic cancer; however, hematologic and renal toxicity were pronounced. Alternative dosing of glufosfamide plus gemcitabine should be explored.

Non-ampullary duodenal adenocarcinoma: factors important for relapse and survival.

BACKGROUND: Duodenal adenocarcinoma (DA) is rare, but potentially curable. Prospective data on treatment outcomes is scarce and large retrospective studies show conflicting results on the impact of radical resection, node-status, and adjuvant therapy. METHODS: In the past 17 years, 30 patients presented with resectable DA. Data on the aforementioned variables were acquired then analyzed for impact on recurrence and survival. RESULTS: Overall-survival rates at 1, 2, and 3 years were 70.0%, 53.3%, and 33.3% respectively. Recurrence-free survival rates at 1, 2, and 3 years were 53.3%, 30.0%, and 26.7%. Overall-survival rates for patients with node-positive disease at 1, 2, and 3 years were 68.8%, 43.8%, 12.5%, and for node-negative 70%, 60%, 60%. Recurrence-free survival in node-positive disease at 1, 2, 3 years was 50%, 12.5%, 12.5%, and for node negative 50%, 50%, and 40%. Median survival from diagnosis was 27.5 months (0.5-226.7 months). Significant predictors of recurrence and survival were nodal-status and AJCC stage (P < 0.001). Adjuvant therapy, surgical-type, pathological tumor-stage, and surgical margins were not significant. CONCLUSION: Nodal-status and overall pathological-stage significantly affect the prognosis for patients with DA, while resection-status and adjuvant therapy may not. The role of adjuvant therapy requires prospective trials for elucidation.

Locally advanced pancreatic cancer: current therapeutic approach.

Even though pancreatic cancer accounts for only 2% of all cancer diagnoses in the U.S., it is the fourth-leading cause of cancer death and one of the most difficult malignancies to manage. Because of the usually late onset of symptoms, only 10%-15% of patients present with resectable disease, whereas the remaining 85%-90% present with locally advanced unresectable or metastatic disease. Despite a lack of consistent evidence from previous clinical trials, chemotherapy in addition to radiation therapy is the most commonly used approach in treating locally advanced pancreatic cancer. The most appropriate chemotherapy in combination with radiation is still debatable between 5-fluorouracil and gemcitabine, and novel trends to prevent resistance and enhance efficacy incorporate biologically targeted agents. This paper reviews the current management options, controversies, and ongoing and future directions for the treatment of locally advanced adenocarcinoma of the pancreas.

Donor chimerism does not predict response to donor lymphocyte infusion for relapsed chronic myelogenous leukemia after allogeneic hematopoietic cell transplantation.

We studied the effect of donor chimerism level on the outcome of donor lymphocyte infusion (DLI) therapy in 42 patients with persistent or relapsed hematologic malignancies after non-T cell-depleted allogeneic hematopoietic cell transplantation. Seventy-five percent of chronic myelogenous leukemia (CML) and 39% of non-CML patients entered remission after DLI therapy. Remission and survival rates were similar for CML patients irrespective of their pre-DLI donor chimerism levels; however, remission occurred sooner in patients with > or =10% pre-DLI donor chimerism. None of the non-CML patients with <10% pre-DLI donor chimerism and 47% of those with > or =10% pre-DLI donor chimerism attained remission. The 2-year survival rates after DLI were 75% for CML and 17% for non-CML patients. We conclude that a low level of donor marrow chimerism is not an adverse prognostic factor for response to DLI in CML patients, but for non-CML patients it may confer worse outcomes. Better methods to augment the response to DLI for patients with hematologic malignancies other than CML that recur after allogeneic hematopoietic cell transplantation are needed, whereas for relapsed CML patients, combination therapies including imatinib mesylate or other promising antileukemic agents may provide outcomes superior to those with DLI alone.

Trastuzumab and interleukin-2 in HER2-positive metastatic breast cancer: a pilot study.

PURPOSE: Trastuzumab as a single agent has activity in metastatic breast cancer; however, the mechanism of action for this clinical activity is uncertain. Whereas interruption of erbB family member signaling occurs, trastuzumab also mediates antibody-dependent cellular cytotoxicity in vitro and in vivo. Based on these data, a clinical trial was performed to test whether interleukin (IL)-2, by increasing FcRgammaIII(+) natural killer (NK) cell numbers and cytolytic function in vivo, when added to trastuzumab, can increase efficacy, be safely given, and avoid the use of chemotherapy. EXPERIMENTAL DESIGN: In this Phase I trial, 10 patients with HER2-overexpressing metastatic breast cancer were treated with IL-2 (1.75 x 10(6) IU/m(2)/day, s.c.) for 7 weeks and trastuzumab (4 mg/kg load and then 2 mg/kg weekly) for 6 weeks. Safety, in vitro immune responses, and clinical responses were assessed. RESULTS: Ten women received a total of 12 cycles of therapy (each cycle lasted 7 weeks). No significant toxicities were seen, and one patient required an IL-2 dose reduction. Among the evaluable patients (10 cycles), the responses were one partial response, five cases of stable disease, and four cases of progressive disease. In vitro immune assays showed NK cell expansion and trastuzumab-mediated increased NK cell killing of breast cancer targets (antibody-dependent cellular cytotoxicity) in a HER2-specific manner but did not correlate with clinical responses. CONCLUSIONS: Trastuzumab + IL-2 is a well-tolerated outpatient regimen that results in NK cell expansion with enhanced in vitro targeted killing of HER2-expressing cells. These preliminary data suggest that this strategy may benefit heavily pretreated metastatic breast cancer patients.

BCR/ABL alters the function of NK cells and the acquisition of killer immunoglobulin-like receptors (KIRs).

Natural killer (NK) cells decrease in function during chronic myelogenous leukemia (CML) progression from chronic phase to blast crisis, and they can become BCR/ABL(+) late in the disease course. To study this altered function, NK92 cells were transduced with the BCR/ABL oncogene. In contrast to the parental cells, which died when deprived of interleukin 2 (IL-2), p210(+) NK92 cells proliferated and survived indefinitely in the absence of IL-2. BCR/ABL also decreased the natural cytotoxicity of NK92 cells against K562 targets, without affecting IL-2, interferon gamma (IFN-gamma), or tumor necrosis factor alpha (TNF-alpha) production. Although the ABL-specific tyrosine kinase inhibitor imatinib mesylate (STI-571) had no effect on parental NK92 cells, it markedly decreased the growth and survival of IL-2-independent p210(+) NK92 cells. In contrast to the parental cell line, serial analysis of p210(+) NK92 cells detected small populations that clonally expressed one or more killer immunoglobulin-like receptors (KIRs). Unlike the decreased natural cytotoxicity, the function of the activating CD158j receptor remained intact. Southern blotting and hybridization with an enhanced green fluorescence protein (eGFP) probe showed that KIR(-) and KIR(+) NK92 cells were all derived from the same clone, suggesting that KIR acquisition remains dynamic at the maturational stage represented by the NK92 cell line. When tested in primary CD56(+bright) NK cells, p210 induced partial IL-2-independent growth and increased KIR expression similar to findings in NK92 cells. This is the first study to show that BCR/ABL, well known for its effects on the myeloid lineage, can alter the function of lymphoid cells, which may be associated with the defect in innate immunity associated with CML progression.