Phase III multicenter randomized trial of oxaliplatin added to chronomodulated fluorouracil-leucovorin as first-line treatment of metastatic colorectal cancer

Adjuvant treatment of colorectal cancer at the turn of the century: European and US perspectives

BACKGROUND

Despite early scepticism, several studies of systemic adjuvant 5-fluorouracil (5-FU)-based chemotherapy demonstrated significant benefits in high-risk colon cancer. As many clinical investigations have since been conducted in this setting, a comprehensive literature review was undertaken to clarify the role of adjuvant therapy in the treatment of colorectal cancer.

DESIGN

Current and future adjuvant treatment approaches in colorectal cancer were reviewed, and differences in the present-day North American and European practices were highlighted.

RESULTS AND CONCLUSIONS

5-FU plus leucovorin for six months is generally considered the 'standard' adjuvant treatment in Dukes' stage C (stage II) colon cancer. Large-scale international trials of other strategies are required to provide further advances in treatment outcome. Following the lead of the USA Intergroup trials, a recently initiated cooperative effort, the Pan-European Trials in Adjuvant Colon Cancer (PETACC), may serve as a European model for such investigations. In T3 and/or lymph-node positive rectal cancer, postoperative (chemo)radiotherapy in the USA is considered the adjuvant treatment of choice. However, most European investigators have advocated for preoperative intensive short-course irradiation instead. Randomized trials in this area are ongoing. In the near future, new drugs for the treatment of colorectal cancer may lead to tailored therapies.

Perioperative radiotherapy and concurrent radiochemotherapy in rectal cancer

Combined modality treatment is the recommended standard adjuvant therapy for patients with locally advanced rectal cancer in the United States and Germany. During the last decade substantial progress has been made in treatment modalities, and surgical management currently includes a broad spectrum of operative procedures ranging from radical operations to innovative sphincter-preserving techniques. Specialized groups have reported excellent local control rates with total mesorectal excision (TME) alone. New and improved radiation techniques (conformal and intraoperative radiotherapy) and innovative schedules (protracted intravenous and chronomodulated infusion) and combinations (oxaliplatin and irinotecan) of chemotherapy may have the potential to further increase the therapeutic benefit of adjuvant treatment. Moreover, the basic issue of timing (pre- or postoperative) within a multimodal regimen is currently being addressed in prospective trials. Evidently there is a need to question the current monolithic approaches, which were established by studies conducted more than a decade ago. It is also under discussion whether to apply the same schedule of postoperative radiochemotherapy to all patients with stage II/III rectal cancer, or to give preoperative intensive short-course radiation according to the Swedish concept for all patients with resectable rectal cancer irrespective of tumor stage and treatment goal (e.g., sphincter preservation). This review discusses different irradiation settings in more recent and ongoing studies of perioperative radiotherapy for rectal cancer, and focuses on the issue of which patient should receive radiotherapy (if at all), and if so, how and when.

Dose escalation of CPT-11 in combination with oxaliplatin using an every two weeks schedule: a phase I study in advanced gastrointestinal cancer patients

BACKGROUND

To determine the dose-limiting toxicity of CPT-11 in combination with oxaliplatin, and the maximal tolerated dose (MTD) and the recommended dose (RD) of CPT-11 using an every two weeks schedule.

PATIENTS AND METHODS

The study was designed to evaluate escalated doses of CPT-11 starting at 100 mg/m2 with a fixed clinically-relevant dose of 85 mg/m2 oxaliplatin given every two weeks.

RESULTS

Twenty-three patients and 186 cycles were evaluable for toxicity (median per patient: 7, range: 1-13). Grade 3 oxaliplatin-induced neurotoxicity was cumulative and limiting in 39% (9 of 23) of patients. The MTD of CPT-11 was 200 mg/m2, with incomplete neutrophil recovery at day 15 as limiting toxicity. At the RD (175 mg/m2 of CPT-11): no grade 4 neutropenia was seen in the two first cycles; 30% of patients experienced grade 3-4 diarrhea. Febrile neutropenia (3.2% of all cycles) was 3-fold more frequent in performance status (PS) 2 than in PS0-1 patients. Among eleven colorectal cancer (CRC) patients, three complete and four partial responses were documented, including in three 5-fluorouracil (5-FU) refractory patients.

CONCLUSION

To combine CPT-11 175 mg/m2 and oxaliplatin 85 mg/m2 every two weeks is feasible in an outpatient setting, and very active in 5-FU resistant CRC patients. A dose of 150 mg/m2 CPT-11 is recommended in PS2 patients.

New developments and approaches in the platinum arena

Following the introduction of cisplatin and the demonstration of its importance in the treatment of testicular and ovarian cancer, there was a need to develop less toxic analogues. Compared with cisplatin, carboplatin proved markedly less toxic to the kidneys and nervous system and caused less nausea and vomiting, while generally (and certainly for ovarian cancer) retaining equivalent antitumour activity. In many situations, carboplatin is now the drug of choice in view of the improved quality of life it offers patients. Many drug combinations involving platinum complexes have been explored, but those with taxanes are particularly noteworthy. Paclitaxel in combination with a platinum agent is now accepted as a standard component of first-line treatment for ovarian cancer, and produces improved survival. Preclinical studies suggested that drugs containing the diaminocyclohexane ligand would be capable of overcoming intrinsic or acquired resistance. However, this outcome was not realised in the clinic until the development of oxaliplatin, which appears to have a different spectrum of activity compared with cisplatin and carboplatin. Oxaliplatin improves the response rate and progression-free survival when given with fluorouracil for the treatment of advanced colorectal cancer, and its activity in other tumour types is under investigation. ZD0473 is a platinum analogue that relies on steric hindrance to overcome thiol-mediated detoxification. It has a good tolerability profile, is currently undergoing phase II testing, and its activity in combination with other agents is being explored. The trinuclear platinum complex BBR3464 also looks promising in preclinical studies and will shortly be evaluated in phase II trials. Although much research remains to be done, these new developments in platinum-based chemotherapy should translate into significant improvements in treatment for patients with a broad range of tumour types.

Oxaliplatin. A review of its pharmacological properties and clinical efficacy in metastatic colorectal cancer and its potential in other malignancies

Oxaliplatin is a platinum compound that inhibits DNA synthesis, primarily by causing intrastrand cross-links in DNA. Oxaliplatin has a broad spectrum of antineoplastic activity and has demonstrated a lack of cross-resistance with other platinum compounds. In patients with metastatic colorectal cancer, intravenous oxaliplatin has been trialled as a monotherapy and in combination with other agents. The highest response rates were achieved when oxaliplatin was used in combination with fluorouracil/folinic acid (leucovorin; calcium folinate), typically > or = 50% in the first-line setting and 13 to 45% as a second-line therapy. First-line triple therapy with oxaliplatin and fuorouracil/folinic acid achieved significantly higher response rates and longer median progression-free survival than fluorouracil/folinic acid therapy alone. However, no significant difference in the median duration of overall survival was found. This may be a consequence of the subsequent use of oxaliplatin and/or surgery after disease progression in patients who relapsed after fluorouracil/folinic acid therapy alone. Neoadjuvant therapy with oxaliplatin/fluorouracil/folinic acid has proven beneficial in enabling surgical removal of previously unresectable liver metastases. In 2 studies, surgery with curative intent was performed in 16 and 51% of patients with initially unresectable liver metastases following oxaliplatin/fluorouracil/folinic acid therapy; the 5-year survival rates were 40 and 50%, respectively. In patients with advanced ovarian cancer, first-line therapy with oxaliplatin/cyclophosphamide achieved an objective response rate which did not differ significantly from that of cisplatin/cyclophosphamide (33 vs 42%). In addition, oxaliplatin has shown efficacy in patients with platinum-pretreated ovarian cancer and achieved objective response rates similar to paclitaxel in this setting (16 vs 17%). Promising results have also been found with oxaliplatin in patients with non-Hodgkin's lymphoma, breast cancer, mesothelioma and non-small cell lung cancer. Reversible, cumulative, peripheral sensory neuropathy is the principle dose-limiting factor of oxaliplatin therapy. Haematological and gastrointestinal toxicities occur frequently but are generally mild to moderate in intensity.

CONCLUSION

Oxaliplatin in combination with fluorouracil/folinic acid is an effective treatment option for patients with metastatic colorectal cancer, both as a first-line therapy and in patients refractory to previous chemotherapy. Although preliminary results failed to show any overall survival advantage of this regimen over fluorouracil/folinic acid alone, this may be a consequence of trial design and requires further examination. Additional clinical investigation of oxaliplatin in patients with other cancers is warranted given the promising results achieved in early trials, most notably in patients with platinum-pretreated ovarian cancer.

Risk factors determining chemotherapeutic toxicity in patients with advanced colorectal cancer

Antitumour therapy in advanced colorectal cancer has limited efficacy. For decades, fluorouracil has been the main anticancer drug for the treatment of colorectal cancer. Recently, however, new agents have been introduced: raltitrexed, irinotecan and oxaliplatin. Currently, the dosage for an individual patient is calculated from the estimated body surface area of the patient. Toxicity, however, frequently necessitates decreasing the dosage, extending the dose interval or even discontinuing treatment. Risk factors with predictive value for toxicity have been identified in several studies. These risk factors are often determined by the pharmacokinetic and pharmacodynamic properties of the drug. In this review, the risk factors for toxicity of the cytotoxic agents used in the treatment of advanced colorectal cancer are considered. For fluorouracil, age, gender, performance status, genetic polymorphism of dihydropyridine dehydrogenase, drug administration schedule, circadian rhythm of plasma concentrations, history of previous chemotherapy-related diarrhoea, xerostomia, low neutrophil levels, and drug-drug interactions have been identified as affecting chemotherapeutic toxicity. For raltitrexed, gender and renal and hepatic impairment, and for oxaliplatin, renal impairment and circadian rhythm of plasma concentrations, respectively, can be considered as risk factors for toxicity. In addition, age, performance status, bilirubinaemia, genetic polymorphism of uridine 5'-diphosphate-glucuronyltransferase-1A1 and drug administration schedule have been shown to be related to irinotecan toxicity. The available literature suggests that dose adjustment based on these risk factors can be used to individualise the dose in order to decrease toxicity and to improve the therapeutic index. This also applies to therapeutic drug monitoring, which has been shown to be effective controlling the toxicity of fluorouracil in some studies. Future research is warranted to assess the potential advantage of dose individualisation of chemotherapy founded on risk factors, over direct dose calculation from the estimated body surface area, with regard to toxicity, therapeutic index, and quality of life, in patients with advanced colorectal cancer.

Leucovorin and fluorouracil with or without oxaliplatin as first-line treatment in advanced colorectal cancer

PURPOSE

In a previous study of treatment for advanced colorectal cancer, the LV5FU2 regimen, comprising leucovorin (LV) plus bolus and infusional fluorouracil (5FU) every 2 weeks, was superior to the standard North Central Cancer Treatment Group/Mayo Clinic 5-day bolus 5FU/LV regimen. This phase III study investigated the effect of combining oxaliplatin with LV5FU2, with progression-free survival as the primary end point.

PATIENTS AND METHODS

Four hundred twenty previously untreated patients with measurable disease were randomized to receive a 2-hour infusion of LV (200 mg/m(2)/d) followed by a 5FU bolus (400 mg/m(2)/d) and 22-hour infusion (600 mg/m(2)/d) for 2 consecutive days every 2 weeks, either alone or together with oxaliplatin 85 mg/m(2) as a 2-hour infusion on day 1.

RESULTS

Patients allocated to oxaliplatin plus LV5FU2 had significantly longer progression-free survival (median, 9.0 v 6.2 months; P =.0003) and better response rate (50.7% v 22.3%; P =.0001) when compared with the control arm. The improvement in overall survival did not reach significance (median, 16.2 v 14.7 months; P =. 12). LV5FU2 plus oxaliplatin gave higher frequencies of National Cancer Institute common toxicity criteria grade 3/4 neutropenia (41. 7% v 5.3% of patients), grade 3/4 diarrhea (11.9% v 5.3%), and grade 3 neurosensory toxicity (18.2% v 0%), but this did not result in impairment of quality of life (QoL). Survival without disease progression or deterioration in global health status was longer in patients allocated to oxaliplatin treatment (P =.004).

CONCLUSION

The LV5FU2-oxaliplatin combination seems beneficial as first-line therapy in advanced colorectal cancer, demonstrating a prolonged progression-free survival with acceptable tolerability and maintenance of QoL.

Oxaliplatin clinical activity: a review

Oxaliplatin (Eloxatin), a recently developed third-generation cisplatin analogue with a 1,2-diaminocyclohexane (DACH) carrier ligand, has displayed preclinical and clinical activity in a wide variety of tumour types. Synergistic with 5-FU in colorectal cancer (CRC), the combination has proven efficacy in 5-FU-resistant advanced disease and in previously untreated CRC, as demonstrated in controlled phase III trials, while evaluation in the adjuvant setting is ongoing. Due to its excellent safety profile, its unique mechanism of action and lack of cross-resistance with other active agents in CRC, oxaliplatin has also been combined with CPT-11 and Raltitrexed with promising results. Trials in pretreated and untreated advanced ovarian cancer (AOC), as a single agent or in combination with cisplatin, cyclophosphamide or paclitaxel, indicate a yet to be defined role in AOC and confirm its lack of cross-resistance with cis/carboplatin. Clinical investigations of single agent and combination therapies in breast, lung, prostate and germ-cell carcinomas, non-Hodgkin's lymphoma and malignant mesothelioma are being pursued. While the role of oxaliplatin in medical oncology is yet to be fully defined, it appears to be an important new anticancer agent.

Dramatic tumor response of bulky liver metastases following treatment with CPT-11 and a chronomodulated 4-day infusion of 5-fluorouracil, folinic acid and oxaliplatin every 2 weeks in a colorectal cancer patient

Three active antitumor agents, i.e. 5-fluorouracil (5-FU), oxaliplatin and CPT-11, are available for the treatment of advanced colorectal cancer (CRC) patients and have been successfully combined in two-drug regimens. Hence, CRC has become a chemosensitive disease, but the optimal combination of these agents in first-line treatment remains to be determined. We report the first case of the combination of CPT-11 with oxaliplatin, 5-FU and folinic acid (FA) as first-line chemotherapy for a patient with a pre-occlusive sigmoid adenocarcinoma and synchronous bulky liver metastases. CPT-11 was given at 125 mg/m2, prior to the start of a chronomodulated 4-day infusion of oxaliplatin 25 mg/m2/day, 5-FU 800 mg/m2/day and FA 300 mg/m2/day repeated every 2 weeks. The doses could be escalated to 150 mg/m2 for CPT-11 and 900 mg/m2/day for 5-FU. After six cycles of chemotherapy 70% reduction in tumor size was documented in the liver. The primary tumor was no longer detectable by barium enema. The toxicity included three episodes of grade 4 neutropenic fever, and two episodes of severe diarrhea and vomiting with dehydration. A cumulative grade 2 neurosensory toxicity was observed after six cycles. Following surgery of the primary tumor, because of the major hepatic tumor response and of the absence of extra-hepatic metastases, the patient might be registered for a liver transplantation program. This first report of combining the three active agents in CRC every 2 weeks led to a high dose intensity of each agent and was associated with a dramatic tumor response of a very advanced disease in a patient with already altered performance status. The antitumor activity in this patient suggests that a three-drug intensified regimen might be feasible and active. A prospective study appears warranted to further examine the efficacy and toxicity of this therapeutic approach, and to determine whether it may increase the fraction of advanced CRC patients becoming resectable. This aggressive chemotherapy program may contribute to a re-examination of the usefulness of liver transplantation in patients with metastatic CRC confined to the liver.

Oxaliplatin: pharmacokinetics and chronopharmacological aspects

Oxaliplatin is the first clinically available diaminocyclohexane platinum coordination complex. The drug is non-cross-resistant with cisplatin or carboplatin and is one of the few active drugs against human colorectal cancer. Its cytotoxicity is synergistic with fluorouracil and folinic acid (leucovorin), the reference treatment for this disease. The main cumulative dose-limiting toxicity of oxaliplatin is peripheral sensory neuropathy. The drug can also produce diarrhoea, vomiting and haematological suppression. Unlike cisplatin, no renal failure or peripheral motor neuropathy have been reported and the sensory neuropathy is partly reversible. Unlike carboplatin, oxaliplatin produces only mild to moderate haematological toxicity. Oxaliplatin undergoes biotransformation into aquated forms in the blood, where 3 species can be found: total platinum, ultrafilterable or 'free' platinum and erythrocyte platinum. Flameless atomic absorption (FAAS) is used for assaying platinum concentration in various tissues. Inductively-coupled plasma mass spectrometry (ICP-MS), with a >10-fold lower sensitivity threshold than FAAS, was also used for the determination of oxaliplatin pharmacokinetics. The pharmacokinetics of oxaliplatin are described by a 3-compartment model. The drug rapidly crosses the cellular membrane as a result of its lipophilicity. Hence, at the end of a 2-hour infusion, approximately 40% of the blood platinum is found in erythrocytes. The distribution half-life of ultrafiltrated plasma platinum ranges from 10 to 25 minutes and its terminal elimination half-life is 26 hours (determined with FAAS) or 270 hours (ICP-MS). The elimination half-life of erythrocytic platinum is 12 to 50 days, close to that of erythrocytes. 30 to 50% of the platinum is recovered in the urine within 2 to 5 days, with renal clearance accounting for half of the total clearance of ultrafiltrated platinum. The total clearance of this species is correlated with the glomerular filtration rate. No pharmacokinetic-pharmacodynamic relationship has been established for oxaliplatin. Pharmacokinetic alterations produced by fluorouracil + folinic acid or irinotecan were minimal if any. The prolonged stability of oxaliplatin makes it suitable for continuous infusions over 4 to 5 days, with a delivery rate which can be either constant or chronomodulated (peak rate at 1600h), using programmable ambulatory pumps. Chronomodulation significantly reduces toxicity and improves antitumour activity as compared with constant rate infusion. These differences in pharmacodynamic properties were paralleled by differences in plasma concentration time courses. The different drug concentration profiles achieved with different infusional modalities may be useful tools for understanding the relationship between the pharmacokinetics and pharmacodynamics of oxaliplatin and may lead to further optimisation of its administration schedule and its combination with other drugs.