A systematic overview of chemotherapy effects in pancreatic cancer

Current state of adjuvant therapy in resected pancreatic adenocarcinoma

Pancreatic carcinoma cannot generally be cured by surgery alone. This review summarizes the development of adjuvant therapy over the past two decades. Four randomized controlled trials compare long-term survival of different treatments. The small GITSG-study supports combined chemoradiation, but the EORTC-study found no significant effect. A Norwegian study of adjuvant chemotherapy found an increased median survival, but no effect beyond two years. The large ESPAC-1 study shows a benefit for 5-FU based chemotherapy, while chemoradiation had a negative effect. Thus, evidence favours adjuvant therapy, but 5-FU may not be the ultimate drug. Support for gemcitabine is given by preliminary data from a German randomized trial, and further American and European studies are upcoming. However, postoperative therapy is problematic, as 20-30% of resected patients never undergo treatment because of slow recovery or other reasons. Preoperative therapy has some theoretical advantages, and moreover, patients with rapidly progressive disease may be spared surgery. Randomized controlled trials are lacking, but published results compare well with postoperative, adjuvant therapy. The value of locally targeted therapy is difficult to assess. Reasonable results have been obtained with regional chemotherapy, whereas intraoperative radiotherapy does not seem to increase survival despite reducing reducing local recurrences.

Long term survivors with metastatic pancreatic adenocarcinoma treated with gemcitabine: a retrospective analysis

BACKGROUND

Metastatic pancreatic adenocarcinoma has a short median overall survival (OS) of 5-6 months. However, a subgroup of patients survives more than 1 year. We analyzed the survival outcomes of this subgroup and evaluated clinical and pathological factors that might affect survival durations.

METHODS

We identified 20 patients with metastatic or recurrent pancreatic adenocarcinoma who received single-agent gemcitabine and had an OS longer than 1 year. Baseline data available after the diagnosis of metastatic or recurrent disease was categorized as: 1) clinical/demographic data (age, gender, ECOG PS, number and location of metastatic sites); 2) Laboratory data (Hematocrit, hemoglobin, glucose, LDH, renal and liver function and CA19-9); 3) Pathologic data (margins, nodal status and grade); 4) Outcomes data (OS, Time to Treatment Failure (TTF), and 2 year-OS). The lowest CA19-9 levels during treatment with gemcitabine were also recorded. We performed a univariate analysis with OS as the outcome variable.

RESULTS

Baseline logarithm of CA19-9 and total bilirubin had a significant impact on OS (HR = 1.32 and 1.31, respectively). Median OS and TTF on gemcitabine were 26.9 (95% CI = 18 to 32) and 11.5 (95% CI = 9.0 to 14.3) months, respectively. Two-year OS was 56.4%, with 7 patients alive at the time of analysis.

CONCLUSION

A subgroup of patients with metastatic pancreatic cancer has prolonged survival after treatment with gemcitabine. Only bilirubin and CA 19-9 levels were predictive of longer survival in this population. Further analysis of potential prognostic and predictive markers of response to treatment and survival are needed.

An explorative randomised phase II study of sequential chemotherapy in advanced upper gastrointestinal cancer

The feasibility, safety, and efficacy of planned sequential administration of docetaxel and irinotecan with 5-fluorouracil (5-FU)/leucovorin in advanced upper gastrointestinal adenocarcinoma (UGIA) are unknown. Seventy-three patients with gastric (GC; n = 22), pancreatic (PC; n = 28) or biliary cancer (BC; n = 23) were randomised to start with 45 mg/m(2) docetaxel or 180 mg/m(2) irinotecan combined with 5-FU/leucovorin every 2nd week. After every 2nd course, the patients were crossed over to the other combination. Treatment was given for a maximum of 12 courses. Quality-of-life (QoL) was evaluated during the first two months using the EORTC QLQ-C30. Eighteen patients (25%; GC 32%, PC 21%, BC 22%) demonstrated partial response (PR) and 21 (29%) had prolonged stable disease. Mean QoL scores were low at baseline. Twenty-three (32%) patients had improved QoL using a summary measure and 13 were stable. Median time to progression was 4.4 months and overall survival 8.2 months. The treatments were reasonably well tolerated. Grade 3-4 toxicities were slightly more common for the docetaxel combination. There were two treatment-related deaths. Planned sequential treatment with docetaxel or irinotecan with 5-FU/leucovorin is feasible, reasonably tolerable and appears active in advanced UGIA.

Fixed dose rate infusion of gemcitabine with oral doxifluridine and leucovorin for advanced unresectable pancreatic cancer: a phase II study

The standard beneficial chemotherapy proven for patients with advanced pancreatic cancer is a regimen containing gemcitabine. In the pregemcitabine era, 5-fluorouracil (5-FU) was the standard agent. Oral 5-FU can be added to gemcitabine to improve the efficacy of chemotherapy and to provide better patient convenience. The possibility to improve efficacy of gemcitabine by fixed dose rate infusion (FDRI) was proposed in addition to combining it with 5-FU. We tried a new chemotherapy combining FDRI of gemcitabine with doxifluridine and leucovorin. Eligibility criteria were pathologically proven, chemotherapy-naïve, and metastatic or nonoperable advanced pancreatic cancer. Gemcitabine 1,000 mg/m(2) was infused over 100 min (days 1, 8 and 15). Doxifluridine 200 mg/m(2) t.i.d. and leucovorin 15 mg b.i.d. were given orally (days 1-21). Chemotherapy was repeated every 28 days until a patient had received 6 cycles or progression was found. Twenty-nine patients were enrolled from October 2002 to December 2004. A total of 78 cycles were given at a mean of 2.7 cycles per patient. Response could be evaluated in 26 patients. Responses were partial remission in 4/26 patients (15.4%), stable disease in 8/26 (30.8%) and progression in 14/26 (53.8%). All patients progressed except for 2 in partial remission and 2 in stable disease. Toxicities could be assessed in 23 patients. Maximal hematological toxicities greater than grade 2 were leucopenia in 3 patients (11.5%), neutropenia in 2 (7.7%), anemia in 2 (7.7%), thrombocytopenia in 1 (3.8%) and febrile neutropenia in 3 (11.5%). Maximal nonhematological grade 3 or 4 toxicities were asthenia in 1 patient (3.8%), anorexia in 1 (3.8%), vomiting in 1 (3.8%), diarrhea in 2 (7.7%), allergic reaction in 1 (3.8%), hand-foot syndrome in 1 (3.8%) and hyperbilirubinemia in 1 (3.8%). All 29 patients were dead on last follow-up. Median progression-free survival was 3.91 months in 26 evaluable patients and median overall survival was 5.59 months in all patients. Combination chemotherapy including FDRI of gemcitabine seems minimally active for patients with advanced, nonoperable pancreatic cancer. Further research to improve effectiveness of chemotherapy for advanced pancreatic cancer is mandatory.

The immunocytokine scFv23/TNF targeting HER-2/neu induces synergistic cytotoxic effects with 5-fluorouracil in TNF-resistant pancreatic cancer cell lines

Human pancreatic tumor cells are highly resistant to both tumor necrosis factor (TNF) and to chemotherapeutic agents. HER-2/neu expression has been proposed as a negative prognostic marker in pancreatic intraepithelial neoplasia. Our approach was to utilize HER-2/neu expression on the surface of tumor cells as a therapeutic target employing scFv23/TNF, immunocytokine composed of a single chain Fv antibody (scFv23) targeting the HER-2/neu and the cytokine TNF as the cytotoxic moiety, to deliver TNF directly to TNF-resistant pancreatic tumor cells. Using a panel of human pancreatic cell lines, which overexpress HER-2/neu, we evaluated the in vitro response of cells to TNF, scFv23/TNF, Herceptin, and a combination of scFv23/TNF with various chemotherapeutic agents. We found that all pancreatic cancer cell lines were highly resistant to the cytotoxic effects of TNF and that scFv23/TNF was highly cytotoxic to TNF-resistant HER-2/neu-expressing pancreatic cancer cell lines at levels rivaling that of conventional chemotherapeutic agents. Combination studies demonstrated a synergistic cytotoxic effect of scFv23/TNF with 5-fluorouracil (5-FU) in TNF-resistant pancreatic cancer cell lines. Mechanistic studies demonstrated that the 5-FU plus scFv23/TNF combination specifically resulted in a down-regulation of HER-2/neu, p-Akt and Bcl-2 and up-regulation of TNF-R1. In addition, the combination 5-FU plus scFv23/TNF induced apoptosis and this synergistic effect was dependent on activation of caspase-8 and caspase-3. Delivery of the cytokine TNF to HER-2/neu expressing pancreatic tumor cells, which are inherently resistant to TNF using scFv23/TNF may be an effective therapy for pancreatic cancer especially when utilized in combination with 5-FU.

Second-line treatment with oxaliplatin, leucovorin and 5-fluorouracil in gemcitabine-pretreated advanced pancreatic cancer: A phase II study

STUDY OBJECTIVES

The present study was conducted to evaluate the efficacy and safety of the combination of Oxaliplatin, Leucovorin and 5-FU as second line therapy, following relapse to Gemcitabine, in patients with advanced adenocarcinoma of the pancreas.

PATIENTS AND METHODS

Patients with advanced pancreatic cancer previously treated with Gemcitabine were included in the study. All patients had histologically or cytologically confirmed adenocarcinoma of the pancreas that was unresectable, locally advanced or metastatic. Treatment consisted of Oxaliplatin 50 mg/m(2) (2-hour iv infusion), followed by Leucovorin 50 mg/m(2) (i.v. bolus) and 500 mg/m(2) 5-FU (1-hour iv infusion), administered weekly, until unacceptable toxicity or disease progression. Objective tumour response and toxicity were evaluated according to World Health Organisation (WHO) criteria.

RESULTS

A total of 30 patients, 20 men and 10 women, median age 63 years (range 52-71 years) and Karnofsky Performance Status (PS) of > or =50 entered the study. The majority of patients (96%) had locally advanced disease. A total of 380 doses of chemotherapy were delivered, a median of 12 doses per patient. Partial responses were observed in 7 patients (PR 23.3%), stable disease in 9 (SD 30.0%), while 14 patients progressed (PD 46.7%). Improved PS was observed in 18 (42.8%) patients. Patients that had responded to first-line Gemcitabine treatment were found more likely to respond or stabilize their disease with second-line treatment. The median duration of response was 22 weeks, and median overall survival was 25 weeks, Grade 3/4 toxicity expressed per chemotherapy dose included leukopenia 16%, anemia 3.2%, thrombocytopenia 3.2%, diarrhea 14.2%, fatigue 16.1% and neurotoxicity 4.2%. Eight patients (27%) suffered a febrile neutropenic event managed successfully with oral antibiotic home therapy, while 17 patients required G-CSF support. There were no treatment related deaths.

CONCLUSIONS

The combination of Oxaliplatin, Leucovorin and 5-FU was tolerated with manageable toxicity, offering encouraging activity as second-line treatment of patients with advanced or metastatic pancreatic adenocarcinoma, previously treated with Gemcitabine. Additional studies are warranted with this regimen in Gemcitabine relapsed pancreatic cancer patients.

Efficacy of systemic therapy in advanced pancreatic carcinoma

With a worldwide incidence of more than 200,000 cases and almost as many deaths, pancreatic carcinoma (PC) remains one of the leading causes of cancer deaths, especially in the Western world. Due to the late onset of symptoms, almost all patients suffer from disseminated disease at the time of diagnosis and only a minority will ever be candidates for radical surgery. Only about one tenth of the operated patients remain disease free. For these reasons, development of effective palliative systemic therapy is important. Almost a decade ago, gemcitabine replaced 5-Fu as the gold standard in systemic treatment of advanced PC. Since then, a number of trials have investigated the potential additional effect of several cytotoxic or targeted agents in combination with gemcitabine. As shown in this review, nearly all these trials have proved disappointing. This review provides an overview of the results of current phase III trials of gemcitabine based systemic therapy. Furthermore, we discuss the role of systemic therapy compared to BSC only and the potential future role of targeted therapies.

Fixed dose-rate infusion of gemcitabine in combination with cisplatin and UFT in advanced carcinoma of the pancreas

BACKGROUND

Gemcitabine is currently considered the standard treatment for advanced pancreatic cancer (APC). Cisplatin and a fluoropyrimidine have some activity in the treatment of this cancer. The aim of this trial is to evaluate the efficacy and toxicity of a fixed dose-rate infusion of gemcitabine associated with cisplatin and UFT in patients with APC.

PATIENTS AND METHODS

Forty-six chemotherapy-naïve patients with APC that was either unresectable or metastatic were included in this phase II study. All of them had Karnofsky performance status > or =50 and unidimensionally measurable disease. Treatment consisted of gemcitabine 1,200 mg/m2 given as a 120-min infusion weekly for three consecutive weeks, cisplatin 50 mg/m2 on day 1 and oral UFT 400 mg/m2/day (in two to three daily doses) on days 1 to 21; cycles of treatment were given every 28 days.

RESULTS

A total of 208 cycles of chemotherapy were given with a median of 4 per patient. Fourteen patients (30%) achieved partial responses (95% CI 19-48%) and 17 (37%) had stable disease. The median time to progression was 5 months, and the median overall survival 9 months. Nineteen patients (49%; 95% CI 32-64%) had a clinical benefit response. Grade 3-4 WHO toxicities were as follows: neutropaenia in 26 patients (57%), with 5 cases of febrile neutropaenia (11%), thrombocytopaenia in 15 (33%), anaemia in six (13%), diarrhoea in 5 (11%), asthenia in 2 (4%) and mucositis in 1 (2%). Seven patients required hospitalisation for treatment-related complications.

CONCLUSION

A fixed dose-rate infusion of gemcitabine associated with cisplatin and UFT is active in patients with APC, though at the cost of considerable toxicity.

Phase I/II trial of intraperitoneal 5-Fluorouracil with and without intravenous Vasopressin in non-resectable pancreas cancer

BACKGROUND

Systemic palliative treatment with chemotherapy against advanced pancreas cancer has low effectiveness despite considerable toxicity.

AIM

To investigate the safety, toxicity and tumour response of intraperitoneal 5-Fluorouracil (5-FU) with intravenous Leucovorin and to monitor 5-FU pharmacokinetics in plasma during intraperitoneal instillation with and without vasopressin in patients with non-resectable pancreas cancer.

PATIENTS/METHODS

Between 1994 and 2003, 68 patients with non-resectable pancreas cancer TNM stage III and IV, were enrolled to receive intraperitoneal5-FU instillation 750-1500 mg/m2 and intravenous Leucovorin 100 mg/m2 for two days every third week. Tumour response, performance status and toxicity were recorded. Seventeen patients were also treated with intravenous vasopressin 0.1 IU/minute for 180 minutes, during intraperitoneal 5-FU instillation. Area under the curve (AUC) and peak concentration (Cmax) of 5-FU in plasma were analysed.

RESULTS

The treatment was well tolerated with minor toxicity. One complete response (54.1+ months) and 2 partial responses were observed. Time to progression was 4.4 months (0.8-54.1+), and median survival was 8.0 months (0.8-54.1+). There was a significant reduction of 5-FU Cmax in plasma the second day of treatment if vasopressin was used (3.4+/-2.5 and 6.1+/-5.4 mumol/l, respectively, p<0.05). 5-FU AUC in plasma was not significantly affected by vasopressin either day of treatment.

CONCLUSION

Intraperitoneal 5-FU is a safe treatment with low toxicity to patients with non-resectable pancreas cancer. Tumour response was 4.4% and median survival time 8.0 months. Addition of vasopressin did not significantly decrease plasma 5-FU AUC but reduced Cmax on day 2 of treatment.

Substantial Changes in Life

There are few studies on patients' perceptions of their situation after being recently diagnosed with an advanced gastrointestinal cancer and those of their spouses. Fourteen patients and their spouses were interviewed separately. The interviews were analyzed using a phenomenographic approach. The analysis indicated that the response categories for patients and spouses were roughly the same, but the number of patients and spouses who made statements differed between categories. All informants perceived substantial changes in life. This included negative physical, mental, and practical changes as well as positive changes. Mental changes included 3 categories: despair, why, and uncertainty. The informants described several ways of handling these changes in life. The most frequently reported by patients were that "one shouldn't complain" and by spouses to "hope," and by all informants to "make the best of it." Other ways of handling the situation were reconciliation, avoidance, preparation for death, seeking support, and isolation. In conclusion, more patients than spouses seemed to accept their situation because fewer patients complained and instead prepared for death, whereas more spouses felt despair, used hope and avoidance, and were preoccupied with practical matters. These findings suggest that spouses are a vulnerable group and healthcare staff should be just as aware of their situation as that of the patients.

Phase II trial of a 24-hour infusion of gemcitabine in previously untreated patients with advanced pancreatic adenocarcinoma

The antitumor effect of gemcitabine is not dose-response related but schedule dependent. Here we report a phase II trial of a weekly 24-hour infusion of gemcitabine in previously untreated patients with advanced pancreatic cancer. Patients with histologically proven, measurable, and irresectable pancreatic adenocarcinoma were treated with gemcitabine at a dose of 100 mg/m2 infused over 24 hr on days 1, 8, and 15. Treatment was repeated every 28 days until progression of disease or limiting toxicity. All 18 patients enrolled were evaluable for response. Neutropenia and thrombocytopenia grade 3 occurred in 1 patient each. One partial response and two minor responses were observed. Median time to progression of disease was 4.4 months. Improvement of the European Organization for Research and Treatment of Cancer C30 scores was observed in 6 patients (pain and overall symptom score, respectively) and in 3 patients (overall functioning score and global quality of life, respectively). Weekly 24-hr gemcitabine was well tolerated in previously untreated patients with advanced pancreatic cancer. It shows marginal antitumor activity in terms of response rate. However, the 24-hr infusion at a dose of 100 mg/m2 seems to be as active as the standard 30-min gemcitabine at a dose of 1000 mg/m2. Relatively long median time to progression of disease and improvement of symptom and quality-of-life scores suggest, that patients may benefit from 24-hr gemcitabine.

Role of adjuvant chemoradiotherapy for abdominal malignancies

The rationale for combining surgery, radiotherapy and chemotherapy is discussed and the clinical results seen with surgery and adjuvant radiochemotherapy in three major abdominal malignancies are reviewed. A systematic approach to the literature was used. In rectal cancer, postoperative radiochemotherapy is an established treatment, although there is weak scientific support for the combined approach. The same clinical gains can also be reached much more easily with preoperative radiotherapy. In gastric cancer, a recent large randomised trial showed improved survival from postoperative radiotherapy. This was not seen in a comparably large trial in pancreatic cancer. The reasons for the different results according to primary tumour site are discussed. It is argued that adequate coverage of all adjacent regional lymph node stations is necessary for an effect on survival.

The cost of treating pancreatic cancer--a cohort study based on patients' records from four hospitals in Sweden

An estimate of the average cost of treatment (COT) was assessed for 53 patients with pancreatic cancer treated between 1997 and 1999 in four hospitals in southern Sweden. Average COT was estimated to Euro18 947, 55% of which was attributable to hospitalization (including surgical procedures), 20% to long-term care and 11% to chemotherapy. Diagnostics and radiotherapy accounted for 9% and 4%, respectively. Median survival was 5.6 months (mean 6.3 months). Treatment costs per patient were negatively correlated with age but were higher for patients receiving chemo/radiotherapy and surgical treatment than for patients receiving only standard supportive care. Disease stage and type of hospital (university versus regional/local hospitals) were not significant predictors of COT per se. Assuming that our estimate of the average cost is representative for Sweden, the total healthcare cost for pancreatic cancer was Euro16 million (dollar14 million), i.e about 2-3% of the COT for all cancer diseases in Sweden. In the USA the cost of pancreatic cancer accounted for the same proportion. However, our estimated cost per patient was about half the amount of the US estimate. The distribution of costs between the different types of treatment services did not differ greatly between Sweden and the USA.

Phase II study of a fixed dose-rate infusion of gemcitabine associated with uracil/tegafur in advanced carcinoma of the pancreas

BACKGROUND

The objectives of this study were to evaluate the efficacy and toxicity of a fixed dose-rate infusion of gemcitabine associated with uracil/tegafur (UFT) in patients with advanced adenocarcinoma of the pancreas.

PATIENTS AND METHODS

Forty-three chemotherapy-naïve patients with adenocarcinoma of the pancreas were included in this phase II study. All of whom had a Karnofsky performance status >or=50 and bi-dimensionally measurable disease (either advanced non-resectable or metastatic); median age 59 years (range 39-77); male:female ratio 29:14. Eight patients (19%) had locally advanced disease and 35 (81%) distant metastases. Treatment consisted of gemcitabine 1200 mg/m(2) given as a 120-min infusion weekly for 3 consecutive weeks, plus oral UFT 400 mg/m(2)/day (in 2-3 doses per day) on days 1-21, cycles were given every 28 days. Measurements of efficacy included response rate, clinical benefit response, time to disease progression and overall survival.

RESULTS

A total of 192 cycles of chemotherapy were delivered with a median of four per patient. There were two complete responses (5%) and 12 partial responses (28%), producing an overall response rate of 33% [95% confidence interval (CI) 16% to 49%]. Thirteen patients (30%) had stable disease, whereas 16 (37%) had a progression. The median time to progression was 6 months and the median overall survival was 11 months. Twenty-five patients (64%, 95% CI 47% to 78%) experienced a clinical benefit response. Grade 3-4 WHO toxicities were: neutropenia in nine patients (21%); thrombocytopenia in four (9%); anaemia in five (12%); diarrhoea in four (9%); and asthenia in one (2%).

CONCLUSIONS

A fixed dose-rate infusion of gemcitabine associated with UFT was well tolerated and showed promising activity in patients with locally advanced or metastatic carcinoma of the pancreas. This is an appropriate palliative treatment in this setting.

Surgical and medical therapy for pancreatic carcinoma

Progress on the treatment of pancreatic ductal adenocarcinoma has involved advances in medical and surgical care with important contributions from disciplines such as radiology and intensive care. In the last decade large randomized controlled trials have been undertaken that demonstrate the improved patient outcomes. There is an increased risk of pancreatic cancer in chronic pancreatitis, hereditary pancreatitis and a variety of familial cancer syndromes. The optimum outcome from pancreatic cancer needs management by multidisciplinary teams in regional specialist units. Endoscopic stenting, good pain relief and pancreatic enzyme supplementation are the basis of care in advanced pancreatic cancer. Chemotherapy prolongs survival in advanced pancreatic cancer with little to be gained using drugs other than 5FU. Resection, if possible, prolongs life and provides the best quality of life. Adjuvant chemoradiotherapy is of no benefit but chemotherapy may improve survival. Alongside the evolution in clinical management has been the elucidation of the molecular events that underlie pancreatic cancer and this knowledge has guided the introduction of targeted treatments for pancreatic cancer.

The role of adjuvant therapy for pancreatic cancer

Patients with pancreatic cancer have a very poor outlook. There have been major advances in the standard surgical treatment of this disease, resulting in decreased post-operative mortality and morbidity. The use of chemotherapy and radiotherapy has been developed to increase long-term patient survival following potentially curative resection. The standard chemotherapeutic agent is 5-fluorouracil (5-FU), although newer cytotoxic agents are in clinical trials for advanced cancer. Initial studies of adjuvant therapy have been based on small numbers of patients, but recently two large European randomised controlled trials of adjuvant therapy (EORTC and ESPAC-1) have been completed. These suggest that adjuvant chemotherapy has a significant survival advantage over resection alone but chemoradiotherapy does not. Promising new agents are being developed and tested mainly in clinical trials of advanced pancreatic cancer. The results of large-scale randomised controlled trials to assess adjuvant therapies for pancreatic cancer demonstrate the great surgical and oncological progress that has been made over the past decade.

Taxotere resistance in SUIT Taxotere resistance in pancreatic carcinoma cell line SUIT 2 and its sublines

AIM: To investigate the specific mechanisms of intrinsic and acquired resistance to taxotere (TXT) in pancreatic adenocarcinoma (PAC).

METHODS: MTT assay was used to detect the sensitivity of PAC cell line SUIT-2 and its sublines (S-007, S-013, S-020, S-028 and TXT selected SUIT-2 cell line, S2/TXT) to TXT. Mdr1 (P-gp), multidrug resistance associated protein (MRP), lung resistance protein (LRP) and β-tubulin isotype gene expressions were detected by RT-PCR. The functionality of P-gp and MRP was tested using their specific blocker verapamil (Ver) and indomethacin (IMC), respectively. The transporter activity of P-gp was also confirmed by Rhodamine 123 accumulation assay.

RESULTS: S-020 and S2/TXT were found to be significantly resistant to TXT (19 and 9.5-fold to their parental cell line SUIT-2, respectively). RT-PCR demonstrated strong expression of Mdr1 in these two cell lines, but weaker expression or no expression in other cells lines. MRP and LRP expressions were found in most of these cell lines. The TXT-resistance in S2-020 and S2/TXT could be reversed almost completely by Ver, but not by IMC. Flow cytometry showed that Ver increased the accumulation of Rhodamine-123 in these two cell lines. Compared with S-020 and SUIT-2, the levels of β-tubulin isotype II, III expressio ns in S-2/TXT were increased remarkably.

CONCLUSION: The both intrinsic and acquired TXT-related drug resistance in these PAC cell lines is mainly mediated by P-gp, but had no relationship to MRP and LRP express ions. The increases of β-tubulin isotype II, III might be collateral changes that occur when the SUIT-2 cells are treated with TXT.