Raltitrexed (Tomudex) in combination with platinum-based agents and/or anthracyclines: preliminary results of phase I clinical trials

Oxaliplatin and Raltitrexed in the Treatment of Inoperable Malignant Pleural Mesothelioma: Results of a Pilot Study

Aims and Background

The treatment of inoperable malignant pleural mesothelioma is a challenge for the oncologist. Available chemotherapy regimens achieve poor results, therefore new agents or combinations are needed. In a phase I study, the combination of oxaliplatin and raltitrexed was shown to be active against malignant pleural mesothelioma. We herein report the results of a pilot study about the treatment of this disease.

Methods

From April 1999 to June 2000, we enrolled 11 chemotherapy-naïve patients with inoperable malignant pleural mesothelioma suitable to receive the following combination chemotherapy: raltitrexed, 3 mg/m2 iv, and oxaliplatin, 130 mg/m2, as a 2-hr infusion every 3 weeks.

Results

Four partial responses, 1 regression of disease (objective response rate, 45%; 95% Cl, 15.6-74.4%), 4 stable diseases and 2 progressions of disease were observed. An improvement in disease-related symptoms was recorded in all responders and in 2 patients with stable disease. Toxicity was mild, with no toxic-related death and only 1 episode of grade 4 neurotoxicity.

Conclusions

We consider the combination promising and worthy of further studies.

Recent advances in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma clinically manifests after decades of initial exposure to etiologic agents, such as asbestos, and presents with nonspecific symptoms such as dyspnea, pain, or weight loss. In patients with limited, resectable disease, surgical therapy with extrapleural pneumonectomy or pleurectomy is recommended, although, it is unclear which approach is superior. Radiation has a limited role and is used primarily for palliation. The palliative efficacy of traditional chemotherapeutic agents and combination regimens is modest at best. The combination of cisplatin and pemetrexed, a novel multitargeted antifolate agent, is the approved "standard of care" for patients with unresectable malignant pleural mesothelioma. A number of molecularly targeted agents are currently under evaluation for mesothelioma such as the Histone deacetylase (HDAC) inhibitors that have demonstrated promising anticancer activity. Vorinostat, a small molecule inhibitor of HDAC, which targets select members of class I and II HDACs, has shown early evidence of activity and is currently being evaluated in a randomized study for patients who progress with standard therapy for advanced mesothelioma. It is hoped that the HDAC inhibitors and other novel targeted agents will pave the way for improved outcomes for patients with this disease.

Phase I study of Tomudex and Doxorubicin in patients with locally advanced, inoperable or metastatic cancer (IND.98)

BACKGROUND

The primary objective of this Phase I study was to determine the maximum tolerated dose (MTD) and recommended phase II dose for Tomudex and Doxorubicin when given in combination to patients with advanced metastatic cancer. The secondary objective was to assess the toxicity profile.

PATIENTS AND METHODS

Starting doses were Tomudex 2.5 mg/m2 i.v. bolus day 1 and Doxorubicin 30 mg/m2 i.v. bolus day 1, repeated every 3 weeks. Doxorubicin was escalated in increments of 10 mg/m2 to 60 mg/m2, followed by escalation of Tomudex in increments of 0.5 mg/m2 to 3.5 mg/m2, on six dose levels. Twenty-five patients received 127 cycles of therapy, with at least 3 patients treated at each dose level.

RESULTS

There was no dose limiting toxicity (DLT) observed in the first five dose levels. Three of six patients on dose level six had DLT. Further dose escalation was not warranted and this was declared the MTD. Grade 3 or 4 granulocytopenia was observed in 16/25 patients, with associated fever in 3/25 patients. Responses were seen in this study with one complete response (duration 12.8 months) and 3 partial responses (median duration 8 months) in 21 evaluable patients. Fourteen patients had stable disease (median duration 2.5 months). All 4 responding patients and 10 patients with stable disease had gastric cancer.

CONCLUSIONS

The recommended phase-II dose for this combination in future studies is Tomudex 3 mg/m2 and Doxorubicin 60 mg/m2 given every 3 weeks.

Malignant mesothelioma: options for management

In the past, there has been a tendency to think of diffuse malignant pleural mesothelioma as one disease in therapeutic terms, regardless of histological type and tumor stage. This does not happen with other tumors, yet it is equally illogical and inappropriate in mesothelioma. As with other tumors, early diagnosis-while the disease is still in stage I, or even at an in situ stage-must be the goal so that therapy can be maximized, particularly if immunotherapy or gene therapy is to be used. Patients with pure epithelial mesothelioma have a better prognosis and respond better to trimodality therapy. Stage I patients who meet fitness criteria should be offered the option of radical surgery in combination with chemotherapy and radiotherapy. Further research is required to determine the optimum neoadjuvant and adjuvant modalities, particularly the timing of individual drugs, use of hyperthermia, and route of administration. The place of immunotherapy and gene therapy as adjunctive treatments also remains to be defined. For example, it may be possible to reduce tumor bulk and perhaps downstage the disease with immunotherapy before radical surgery, if treatment is started early enough. Gene therapy may have a role either preoperatively or in destroying the microscopic disease that remains after radical surgery. These and other combinations of treatment need to be tested in well-designed clinical trials, probably on a multicenter basis (to enroll a sufficient number of patients). Finding the means to improve treatment for sarcomatous and mixed histology mesothelioma remains a challenge. At present, radical surgery does not seem worthwhile for these patients when combined with currently employed chemotherapy and radiotherapy; however, chemotherapy combinations used for treating other sarcomas need to be evaluated as adjunctive therapy before radical surgery is abandoned altogether as a mode of treatment. A collaborative approach involving thoracic surgeons, basic scientists and oncologists, and physicians with experience in treating mesothelioma is essential. Despite its increasing frequency, mesothelioma is still a relatively rare tumor, so treatment should be concentrated in relatively few supraregional centers to maximize expertise and allow innovative treatment combinations to be implemented with the greatest chance of success. Evaluation of new therapeutic approaches will be achieved more rapidly if these supraregional centers collaborate in multicenter trials. The nihilistic approach of simply waiting until the mesothelioma epidemic eventually begins to decline spontaneously in 20 or 30 years is untenable in view of the hundreds of thousands of deaths that will result if no effective treatment is found.

A phase II study of epirubicin, cisplatin and raltitrexed combination chemotherapy (ECT) in patients with advanced oesophageal and gastric adenocarcinoma

BACKGROUND

The aim of this study was to evaluate the efficacy of the combination of epirubicin, cisplatin and ralitrexed (Tomudex). ECT, in patients with advanced oesophageal or gastric adenocarcinoma. Efficacy was assessed primarily as response rate and secondarily in terms of toxicity, time to progression and survival.

PATIENTS AND METHODS

Twenty-one patients with histologically and/or cytologically proven unresectable (7) or metastatic (14) gastro-oesophageal adenocarcinoma, who had bi-dimensionally measurable disease, with ECOG performance status < or = 2. with adequate haematological, hepatic and renal function received first-line chemotherapy with epirubicin (50 mg/m2). cisplatin (60 mg/m2) and Tomudex (2.5 mg/m2), ECT, at three-weekly intervals. Treatment consisted of three cycles of chemotherapy, with a further three cycles if there was disease response or stabilisation.

RESULTS

ECT is an active regimen in the treatment of advanced gastro-oesophageal adenocarcinoma with an overall intention-to-treat response rate of 29% (95% confidence intervals (CI): 11%-52%). In addition, 4 (19%) patients had stable disease. Median time to progression was 19 weeks (95% CI: 7-31 weeks). Median overall survival was 18 weeks (95% CI: 11-24 weeks). Seventeen patients failed to complete the six cycles of treatment due to disease progression (5). toxicity (3), non-toxic death (1 pulmonary embolism, 1 cardiac), severe allergy to epirubicin (1), patient decision (1) and five patients after the study was discontinued early due to toxicity. There were three toxic deaths: two due to sepsis complicating neutropaenia and one due to cardiorespiratory failure following drug induced enteritis. Nine patients experienced grade 3 or 4 neutropaenia, two patients experienced grade 3 or 4 nausea and vomiting and one patient had grade 4 diarrhoea.

CONCLUSIONS

The combination of epirubicin, cisplatin and tomudex is active against advanced gastro-oesophageal adenocarcinoma but the toxicity suggests that further evaluation in a randomised comparison to ECF is not appropriate.

Phase I trial of sequential administration of raltitrexed (Tomudex) and 5-iodo-2'-deoxyuridine (IdUrd)

Raltitrexed (Tomudex) is a specific inhibitor of thymidylate synthase with clinical activity in colorectal cancer. The combination of raltitrexed and 5-iodo-2'-deoxyuridine (IdUrd, a cytotoxic pyrimidine analog) resulted in increased IdUrd incorporation into DNA and exhibited in vitro synergism against colon and bladder human carcinoma cell lines. We designed a phase I trial to determine the MTD, pharmacokinetics, and biologic effects of escalating doses of the combination of IdUrd given as a 24-hour infusion after a raltitrexed 15-minute infusion every three weeks. Thirty-four patients received 95 courses of raltitrexed and IdUrd at doses ranging from raltitrexed 1 mg/m2 and IdUrd 750 mg/m2 to raltitrexed 2.5 mg/m2 and IdUrd 10,400 mg/m2. The median number of cycles administered was 2 (range 1-10). Dose limiting hematologic toxicity occurred at doses of raltitrexed 2.5 mg/m2 and IdUrd 10,400 mg/m2. In addition, we determined the mean plasma concentrations C(SS) of IdUrd, the iodouracil level at 22 hours and the IdUrd clearance. Raltitrexed did not appear to affect the pharmacokinetics of IdUrd in the dose range tested. The recommended phase II dose is raltitrexed 2 mg/m2 and IdUrd 10,400 mg/m2 repeated every three weeks. Evidence of potential antitumor activity was observed: 1 patient (with colon cancer) had a partial response while 15 others had stable disease.

Fibrous tumors of the pleura

Fibrous tumor of the pleura is a rare tumor arising from mesenchymal cells underlying the visceral or parietal pleura. The tumor may have benign or malignant histological features, but these do not always predict the clinical behavior of the tumor. In most cases, the tumor appears pedunculated, and simple resection of the tumor is curative even if significant cellular atypia is present. In contrast, some tumors with a broad base of attachment may recur and occasionally become malignant. Complete surgical resection is the mainstay of therapy for both benign and malignant fibrous tumors of the pleura. When resection is incomplete or impossible, external radiation therapy with or without chemotherapy is recommended.

Raltitrexed ('Tomudex') and radiotherapy can be combined as postoperative treatment for rectal cancer

BACKGROUND

The optimal adjuvant therapy for operable rectal cancer is likely to be a combination of radiotherapy and chemotherapy. Raltitrexed ('Tomudex') is a specific thymidylate synthase inhibitor with a convenient administration schedule, acceptable and manageable toxicity, radiosensitising properties, and proven efficacy in the treatment of advanced colorectal cancer. It may, therefore, offer advantages compared with standard 5-FU chemotherapy regimens used in colorectal cancer. The aim of this phase I, dose-escalation study was to determine the recommended dose of raltitrexed for use with postoperative pelvic radiotherapy in patients with rectal cancer.

PATIENTS AND METHODS

Patients with resected Dukes' stage B or C rectal cancer were treated with a combination of raltitrexed and radiotherapy (50.4 Gy at 1.8 Gy per fraction over five to six weeks). At least three patients were treated at each of three escalating raltitrexed dose levels (2.0, 2.6 and 3.0 mg/m2) once every three weeks. Toxicity was assessed by the recording of WHO adverse events and biochemistry and haematology determinations.

RESULTS

A total of 22 patients entered the study, 17 of whom had Dukes' stage C disease. All three patients entered at a dose level of 3.0 mg/m2 experienced dose-limiting toxicity (DLT) (2 patients had grade 3 leucopenia and 1 patient had grade 2 leucopenia and grade 3 diarrhoea); however, only 2 of 1 patients entered at a dose level of 2.6 mg/m2 experienced DLT (1 patient had grade 4 neutropenia and 1 patient died probably due to aspiration pneumonia unrelated to treatment). The most common haematological toxic events were leucopenia (8 patients) and anaemia (6 patients). Only four haematological or biochemical toxic events were of grade 3 or 4. Other common toxicities were diarrhoea and nausea, which occurred in 15 and 9 patients, respectively.

CONCLUSIONS

This study demonstrates that raltitrexed can be combined with postoperative radiotherapy for treatment of patients with Dukes' stage B or C rectal cancer. The recommended dose of raltitrexed in this setting is 2.6 mg/m2, which is close to the full monotherapy dose.