Improvements in Survival and Clinical Benefit With Gemcitabine as First-Line Therapy for Patients With Advanced Pancreas Cancer: A Randomized Trial.

PURPOSE: Most patients with advanced pancreas cancer experience pain and must limit their daily activities because of tumor-related symptoms. To date, no treatment has had a significant impact on the disease. In early studies with gemcitabine, patients with pancreas cancer experienced an improvement in disease-related symptoms. Based on those findings, a definitive trial was performed to assess the effectiveness of gemcitabine in patients with newly diagnosed advanced pancreas cancer. PATIENTS AND METHODS: One hundred twenty-six patients with advanced symptomatic pancreas cancer completed a lead-in period to characterize and stabilize pain and were randomized to receive either gemcitabine 1,000 mg/m2 weekly x 7 followed by 1 week of rest, then weekly x 3 every 4 weeks thereafter (63 patients), or to fluorouracil (5-FU) 600 mg/m2 once weekly (63 patients). The primary efficacy measure was clinical benefit response, which was a composite of measurements of pain (analgesic consumption and pain intensity), Karnofsky performance status, and weight. Clinical benefit required a sustained (> or = 4 weeks) improvement in at least one parameter without worsening in any others. Other measures of efficacy included response rate, time to progressive disease, and survival. RESULTS: Clinical benefit response was experienced by 23.8% of gemcitabine-treated patients compared with 4.8% of 5-FU-treated patients (P = .0022). The median survival durations were 5.65 and 4.41 months for gemcitabine-treated and 5-FU-treated patients, respectively (P = .0025). The survival rate at 12 months was 18% for gemcitabine patients and 2% for 5-FU patients. Treatment was well tolerated. CONCLUSION: This study demonstrates that gemcitabine is more effective than 5-FU in alleviation of some disease-related symptoms in patients with advanced, symptomatic pancreas cancer. Gemcitabine also confers a modest survival advantage over treatment with 5-FU.

The role of nonrandomized trials in the evaluation of oncology drugs.

Although randomized trials provide the most reliable evidence of a drug's safety and efficacy, there are situations where randomized trials are not possible or ethical. In this article we discuss when and how single-arm trials can be used to support full approval of oncology drugs. These include situations in which an unprecedented effect on tumor response is observed in a setting of high unmet medical need, clinical trial patients have been well characterized, enabling a target population to be clearly defined, experience exists in a sufficient number of patients to allow adequate assessment of the risk:benefit relationship, and a proper historical context can be provided for analysis. We also discuss how response rates might be considered predictive of long-term outcomes or clinically meaningful in and of themselves in certain contexts.

Multicenter phase II trial of adjuvant therapy for resected pancreatic cancer using cisplatin, 5-fluorouracil, and interferon-alfa-2b-based chemoradiation: ACOSOG Trial Z05031.

BACKGROUND: The American College of Surgeons Oncology Group sought to confirm the efficacy of a novel interferon-based chemoradiation regimen in a multicenter phase II trial. PATIENTS AND METHODS: Patients with resected (R0/R1) adenocarcinoma of the pancreatic head were treated with adjuvant interferon-alfa-2b (3 million units s.c. on days 1, 3, and 5 of each week for 5.5 weeks), cisplatin (30 mg/m(2) i.v. weekly for 6 weeks), and continuous infusion 5-fluorouracil (5-FU; 175 mg·m(2)/day for 38 days) concurrently with external-beam radiation (50.4 Gy). Chemoradiation was followed by two 6-week courses of continuous infusion 5-FU (200 mg·m(2)/day). The primary study end point was 18-month overall survival from protocol enrollment (OS18); an OS18 ≥65% was considered a positive study outcome. RESULTS: Eighty-nine patients were enrolled. Eighty-four patients were assessable for toxicity. The all-cause grade ≥3 toxicity rate was 95% (80 patients) during therapy. No long-term toxicity or toxicity-related deaths were noted. At 36-month median follow-up, the OS18 was 69% [95% confidence interval (CI) 60% to 80%]; the median disease-free survival and overall survival were 14.1 months (95% CI 11.0-20.1 months) and 25.4 months (95% CI 23.4-34.1 months), respectively. CONCLUSIONS: Notwithstanding promising multi-institutional efficacy results, further development of this regimen will require additional modifications to mitigate toxic effects.

Incidence and evolution of oxaliplatin-induced peripheral sensory neuropathy in diabetic patients with colorectal cancer: a pooled analysis of three phase III studies.

BACKGROUND: The purpose of this study was to determine whether the presence of diabetes mellitus (DM) influences the incidence, severity, and/or course of peripheral sensory neuropathy (PSN) after oxaliplatin (FOLFOX) therapy in patients with colorectal cancer (CRC). METHODS: A retrospective pooled analysis incorporating three phase III studies was conducted: Multicenter International Study of Oxaliplatin, 5-Fluorouracil, and Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC) (adjuvant treatment; stage II/III colon cancer), EFC4584 (second-line treatment; metastatic CRC), and EFC2962 (first-line treatment; metastatic CRC). Patients were ineligible for the studies if they had known PSN (EFC4584) or PSN grade > or =1 (MOSAIC and EFC2962) at baseline. The incidence of PSN was evaluated retrospectively in patient subgroups with or without DM at baseline that received FOLFOX. Kaplan-Meier curves were used to assess the probability of PSN with increasing cumulative oxaliplatin dose. RESULTS: Of 1587 patients enrolled across the three studies, 135 (8.5%) had DM at baseline. The incidence of PSN (non-DM/DM) was 45.0%/46.7% (grade 1), 28.6%/26.7% (grade 2), and 13.0%/12.6% (grade 3). The probability of PSN by cumulative dose of oxaliplatin was similar in DM and non-DM patients. CONCLUSIONS: This retrospective analysis indicates that oxaliplatin-based therapy does not influence the incidence, severity, or time to onset of PSN in asymptomatic DM patients with CRC who meet eligibility criteria for clinical trials.

Capecitabine plus oxaliplatin (XELOX) versus 5-fluorouracil/folinic acid plus oxaliplatin (FOLFOX-4) as second-line therapy in metastatic colorectal cancer: a randomized phase III noninferiority study.

BACKGROUND: To demonstrate the noninferiority of capecitabine plus oxaliplatin (XELOX) versus 5-fluorouracil/folinic acid and oxaliplatin (FOLFOX-4) as second-line therapy in patients with metastatic colorectal cancer after prior irinotecan-based chemotherapy. PATIENTS AND METHODS: A total of 627 patients were randomly assigned to receive XELOX (n = 313) or FOLFOX-4 (n = 314) following disease progression/recurrence or intolerance to irinotecan-based chemotherapy. The primary end point was progression-free survival (PFS). RESULTS: PFS for XELOX was noninferior to FOLFOX-4 [hazard ratio (HR) = 0.97; 95% confidence interval (CI) 0.83-1.14] in the intention-to-treat (ITT) population. Median PFS was 4.7 months with XELOX versus 4.8 months with FOLFOX-4. The robustness of the primary analysis was supported by multivariate and subgroup analyses. Median overall survival in the ITT population was 11.9 months with XELOX versus 12.5 months with FOLFOX-4 (HR = 1.02; 95% CI 0.86-1.21). Treatment-related grade 3/4 adverse events occurred in 50% of XELOX- and 65% of FOLFOX-4-treated patients. Whereas grade 3/4 neutropenia (35% versus 5% with XELOX) and febrile neutropenia (4% versus < 1%) were more common with FOLFOX-4, grade 3/4 diarrhea (19% versus 5% with FOLFOX-4) and grade 3 hand-foot syndrome (4% versus < 1%) were more common with XELOX. CONCLUSION: XELOX is noninferior to FOLFOX-4 when administered as second-line treatment in patients with metastatic colorectal cancer.

Phase I trial of oral MAC-321 in subjects with advanced malignant solid tumors.

PURPOSE: MAC-321 is a novel taxane that has demonstrated exceptional activity in human xenograft models when administered intravenously and orally. Preclinical studies of MAC-321 have shown antitumor activity in MDR-expressing and paclitaxel-resistant tumors. This phase I dose escalation study was performed to determine the safety, tolerability, and pharmacokinetic profile of orally administered MAC-321 given once every 21 days. Preliminary antitumor activity of MAC-321 was also examined. METHODS: Key eligibility criteria included adult subjects with refractory solid tumors or solid tumors for which conventional therapy was unsuitable or did not exist, good performance status (ECOG ( 2), and adequate hematologic, hepatic, and renal functions. Plasma pharmacokinetic (PK) sampling was performed during the first cycle of therapy. RESULTS: Five dose levels of MAC-321 ranging from 25 to 75 mg/m(2) were evaluated in 18 subjects (four women and 14 men). MAC-321 was well tolerated at the first three dose levels (25, 37, 50 mg/m(2)). Two subjects developed dose-limiting toxicities (DLTs) at 75 mg/m(2); one subject with grade 3 and one subject with grade 4 neutropenia with fever. Three subjects treated at an intermediate dose level of 60 mg/m(2) had no DLTs. However, the study was terminated prior to completion of the maximal tolerated dose cohort after subjects treated with intravenous MAC-321 in a concurrent study experienced life-threatening toxicities. Other common toxicities included grades 1-2 fatigue and grades 1-2 diarrhea. There was substantial interpatient variability in the PK parameters. MAC-321 was rapidly absorbed with a mean C (max) value of less than 1 h. Mean C (max) and AUC values generally increased in a dose-related manner. The median terminal phase elimination half-life was 45 h (range 20-228 h). Disease stabilization was seen in four subjects with the following tumors: mesothelioma (14 cycles), chondrosarcoma (12 cycles), small cell carcinoma (10 cycles), and prostate carcinoma (6 cycles). CONCLUSIONS: MAC-321 can be safely administered orally once every 21 days up to a dose of 60 mg/m(2). The major DLT was neutropenic fever. Four subjects had disease stabilization.

Long-term follow-up of a phase II trial of oral altretamine for consolidation of clinical complete remission in women with stage III epithelial ovarian cancer in the Southwest Oncology Group.

OBJECTIVE: This report provides follow-up progression-free survival (PFS) and median survival data for women who achieved clinical complete remission (cCR) from stage III ovarian cancer after first-line therapy and were treated with altretamine consolidation therapy. METHODS: Patients who enrolled in the SWOG 9326 study from September 1993 to July 1997 were required to have documented cCR from stage III ovarian cancer following front-line platinum-based therapy. Treatment consisted of 6 months of oral altretamine at 260 mg/m(2)/day for 14 consecutive days of a 28-day cycle. RESULTS: Ninety-seven of 112 enrolled patients were evaluable for efficacy. This report presents median 6.2-year follow-up, dating from study registration. Median PFS was 28 (95% CI: 19-43) months. Median PFS for patients with optimal disease was 45 (95% CI: 27-48) months and for patients with suboptimal disease was 17 (95% CI: 12-26) months. Twenty-six of 61 (43%) patients with optimally debulked lesions and 5 of 36 (14%) patients with suboptimally debulked lesions remained disease free. Median survival of patients with optimally debulked disease has not been reached; median survival of patients with suboptimally debulked disease was 39 (95% CI: 19-51) months. No treatment-related adverse events were reported during the follow-up period. CONCLUSIONS: Consolidation therapy with oral altretamine was generally well tolerated and associated with prolonged progression-free and overall survival in the Phase II setting.

Clinical studies in patients with solid tumors using a second-generation antisense oligonucleotide (GEM 231) targeted against protein kinase A type I.

GEM 231 is a second-generation antisense oligonucleotide targeted against the RIalpha regulatory subunit of cAMP-dependent protein kinase type I (PKA-I). Excessive expression of PKA-I is associated with cell proliferation and transformation, and increased levels of secreted extracellular PKA (ECPKA) are found in the serum of cancer patients. Preclinical studies have demonstrated single-agent antitumor activity of GEM 231 in a variety of human cancer xenograft models, and additive or synergistic antitumor activity has been observed with taxane and/or camptothecin-based combinations. Based on prior safety (MTD) data demonstrating dose-dependent, reversible, and cumulative transaminitis, and high peak plasma concentration (Cmax)-dependent changes in activated partial thromboplastin time (aPTT) with GEM 231 2-h twice-weekly infusions, an alternative schedule of GEM 231 given as a single agent was evaluated in patients with advanced solid tumors. Fourteen patients (median age approximately 60 yrs) with advanced solid malignancies received a total of 78 weeks of therapy. GEM 231 was infused via a CADD pump at 80 mg/m2/day (d) for 3 d/wk (n = 1), then for 5 d/wk at 80 (n = 3), 120 (n = 8), and 180 mg/m2/d (n = 2). One cycle was defined as 4 weeks of therapy. Apparent dose dependency for the occurrence of transaminitis was readily reversible. At 180 mg/m2/d, 2 of 2 patients had cycle 1 dose-limiting toxicity (DLT) transaminitis. One patient treated at 120 mg/m2/d experienced grade 3 transaminase elevations after 8 weeks of therapy, but when serum transaminase values rapidly improved he resumed treatment at 80 mg/m2/d for 6 weeks until tumor progression was documented. Another patient at 120 mg/m2/d developed grade 3 esophagitis after 3 weeks, limiting further dosing. One patient (lung cancer) demonstrated stable disease for 9 weeks. Overall, plasma aPTT was minimally prolonged and changes were transient, peaked at the end of each infusion, and were not associated with spontaneous bleeding. A constitutive symptom (e.g., low-grade fatigue) was common, cumulative, and reversible following discontinuation of therapy. Serum ECPKA was measured by enzymatic assay and Western blotting from blood drawn at the beginning and end of each infusion. Serum ECPKA levels demonstrated a trend to decline with the treatment. In addition to single agent schedules, combination trials were undertaken to assess safety and possible interaction of GEM 231 with taxanes (paclitaxel, docetaxel), given once every 3 weeks (one cycle). While trials using the 2-h twice-weekly GEM 231 infusions are ongoing, preliminary results from both studies show that it is safe to combine paclitaxel or docetaxel with GEM 231. Overall, it is also feasible to administer GEM 231 in combination with taxane or nontaxane chemotherapy (e.g., camptothecins). Phase I combination studies are currently underway to further explore the clinical, pharmacokinetic, and biologic profile of GEM 231 with chemotherapy.

Phase II trial of 5-fluorouracil plus eniluracil in patients with advanced pancreatic cancer: a Southwest Oncology Group study.

BACKGROUND: Eniluracil is a potent, irreversible inactivator of dihydropyrimidine dehydrogenase, the major catabolic enzyme for 5-fluorouracil (5-FU). Pretreatment with eniluracil significantly increases plasma half-life, plasma concentration and oral bioavailability of 5-FU. This multicenter phase II trial was designed to estimate the 6-month survival rate in patients with metastatic adenocarcinoma of the pancreas treated with 5-FU and eniluracil. PATIENTS AND METHODS: One hundred and sixteen patients (61 with no prior chemotherapy and 55 with prior chemotherapy) were registered for treatment with eniluracil 50 mg (total dose) p.o. on days 1-7 and 5-FU 20 mg/m(2)/day p.o. on days 2-6 of a 28-day treatment cycle. RESULTS: In 106 patients evaluable for survival, the 6-month survival rate was 34% [95% confidence interval (CI) 22% to 47%, median survival 3.6 months] for patients who had not been treated previously with chemotherapy and 29% (95% CI 16% to 42%, median survival 3.4 months) for those who had received prior chemotherapy. For those patients with measurable disease, the confirmed response rates were 8% and 2%, respectively. The most common grade 3-4 toxicities were neutropenia (29% of patients) and diarrhea (12% of patients). Overall, 69% of patients experienced a grade 3 or worse adverse event during treatment. CONCLUSIONS: These results suggest that the combination of a 7-day course of eniluracil and a 5-day course of oral 5-FU has limited activity in patients with advanced pancreatic cancer, and is associated with a high frequency of clinically significant adverse events.

Mortality associated with irinotecan plus bolus fluorouracil/leucovorin: summary findings of an independent panel.

PURPOSE: To review and assign attribution for the causes of early deaths on two National Cancer Institute-sponsored cooperative group studies involving irinotecan and bolus fluorouracil (5-FU) and leucovorin (IFL). PATIENTS AND METHODS: The inpatient, outpatient, and research records of patients treated on Cancer and Leukemia Group B protocol C89803 and on North Center Cancer Treatment Group protocol N9741 were reviewed by a panel of five medical oncologists not directly involved with either study. Each death was categorized as treatment-induced, treatment-exacerbated, or treatment-unrelated. RESULTS: The records of 44 patients who experienced early deaths on C89803 (21 patients) or N9741 (23 patients) were reviewed. Patients treated with irinotecan plus bolus 5-FU/leucovorin had a three-fold higher rate of treatment-induced or treatment-exacerbated death than patients treated on the other arm(s) of the respective studies. For C89803, these rates were 2.5% (16 of 635) for IFL versus 0.8% (five of 628) for bolus weekly 5-FU and leucovorin. For N9741, these rates were 3.5% (10 of 289) for IFL, 1.1% (three of 277) for oxaliplatin plus bolus and infusional 5-FU and leucovorin, and 1.1% (three of 275) for oxaliplatin plus irinotecan. Multiple gastrointestinal toxicities that often occurred together were characterized into a gastrointestinal syndrome. Sudden, unexpected thromboembolic events were characterized as a vascular syndrome. The majority of deaths in both studies were attributable to one or both of these syndromes. CONCLUSION: Close clinical monitoring, early recognition of toxicities and toxicity syndromes, aggressive therapeutic intervention, and withholding therapy in the presence of unresolved drug-related toxicities is recommended for patients receiving IFL or other intensive chemotherapy regimens.

Phase II trial of oral altretamine for consolidation of clinical complete remission in women with stage III epithelial ovarian cancer: a Southwest Oncology Group trial (SWOG-9326).

OBJECTIVE: The aim of this study was to evaluate the 2-year survival rate in a group of women in complete clinical remission (cCR) from Stage III ovarian cancer following front-line therapy who were then treated with a 6-month course of altretamine. METHODS: Patients were documented to be in cCR by physical examination, computed tomography or magnetic resonance imaging scan, and serum CA-125. Treatment consisted of altretamine (Hexalen) 260 mg/m(2)/day po divided into four doses taken after meals and at bedtime for 14 of 28 days for six cycles. Based on previous experience in the Southwest Oncology Group, the treatment would be considered promising if the 2-year survival rate was > or = 65% as measured from study registration. RESULTS: From 9/1/93 and 7/1/97, 112 patients were registered and 97 were fully evaluable. The majority of patients had optimally debulked (< or = 1 cm: 63%), high-grade (Grade 3: 82%) tumors. The 2-year survival rate in this study was 75% (95% CI: 66-84%). For those patients with optimal disease, the 2-year survival rate was 82% (95% CI: 72-92%) and for those with suboptimal disease it was 64% (95% CI: 48-79%). Four patients (4%) experienced Grade 4 and 21 patients (22%) experienced Grade 3 toxicities consisting primarily of nausea/vomiting, neutropenia, fatigue, anxiety, and paresthesias. CONCLUSIONS: The 2-year survival rate in this study warrants further evaluation of consolidation therapy for women in clinical complete remission following front-line chemotherapy for Stage III ovarian cancer. Caution is advised in the interpretation of these data, however, because of the nonrandomized nature of the trial and the unknown contribution of front-line use of paclitaxel to the durability of clinical complete response.

Irinotecan (CPT-11): recent developments and future directions--colorectal cancer and beyond.

Since its approval in the United States in 1996, irinotecan (CPT-11, Camptosar, Pharmacia Corp.; Peapack, NJ) has undergone extensive clinical evaluation. In the past five years, the focus of development has evolved from evaluation of single-agent activity in refractory disease settings to evaluation of front-line irinotecan-based combination chemotherapy regimens and integration of irinotecan into combined modality regimens. Important studies have been performed clarifying the role of irinotecan in treating colorectal and other gastrointestinal cancers, small cell and non-small cell lung cancer, and a variety of other malignancies. Preclinical studies performed in conjunction with these clinical trials have also provided significant insights into the pharmacology, metabolism, mechanisms of resistance, and molecular determinants of response. This review summarizes that progress, focusing on the achievements of the past five years.

A phase II study of irinotecan with 5-fluorouracil and leucovorin in patients with previously untreated gastric adenocarcinoma.

BACKGROUND: A phase II study testing the safety and efficacy of irinotecan (CPT-11). 5-fluorouracil (5-FU), and leucovorin (LCV) was conducted in patients with advanced gastric adenocarcinomas. PATIENTS AND METHODS: Patients with metastatic or recurrent adenocarcinoma of the gastroesophageal junction (GEJ) or stomach were entered onto this study. Previous chemotherapy for metastatic disease was not allowed. Treatment consisted of repeated 6-week cycles comprising CPT-11 125 mg/m2 intravenously (i.v.) followed immediately by LCV 20 mg/m2 i.v. and 5-FU 500 mg/m2 i.v., all given weekly for four weeks followed by a two-week rest. RESULTS: Thirty-eight patients were enrolled and 36 eligible patients received protocol therapy. Grade 3-5 toxicities consisted primarily of neutropenia (36%) and diarrhea (28%). Neutropenic infection was observed in 14% of patients, with 3 (8%) dying of neutropenic sepsis. The overall response rate was 22% (95% confidence interval [CI] 8.5% to 35.5%). Median survival was 7.6 months, and median time to progression was 4.4 months. CONCLUSION: This weekly regimen of CPT-11 with bolus 5-FU/LCV is active in patients with advanced adenocarcinomas of the stomach or gastroesophageal junction. While rates of grade 3-4 neutropenia and diarrhea were similar to those observed historically in patients receiving this regimen for colorectal cancer, neutropenic fever/sepsis appeared to be more frequent, and dose modifications were substantial. Future trials of this combination in patients with gastric cancer should decrease the absolute starting drug doses and/ or employ altered scheduling that better accommodates the pattern of toxicity.

Phase I dose-finding and pharmacokinetic trial of irinotecan (CPT-11) administered every two weeks.

OBJECTIVES: This trial was performed to determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetic profile of irinotecan (CPT-11) when administered on a once-every-2-week schedule. PATIENTS AND METHODS: CPT-11 was administered to successive cohorts of patients at progressively increasing starting doses ranging from 125 to 350 mg/m2. The MTD and DLTs were determined both for CPT-11 alone and for CPT-11 followed by filgrastim (G-CSF). Plasma samples were obtained during the first 24 hours after initial dosing to determine the total concentrations (lactone + carboxylate forms) of CPT-11; of the active metabolite SN-38; and of SN-38 glucuronide (SN-38G). RESULTS: Neutropenic fever was the DLT for CPT-11 at the 300 mg/m2 dose level. When G-CSF was added, dose escalation beyond 350 mg/m2 could not be achieved due to grade 2-3 toxicities that prevented on-time retreatment with CPT-11. Severe, late diarrhea was uncommon on this schedule. Peak plasma concentrations of SN-38 and SN-38G were approximately 2.5% and 4.2% of the corresponding peak plasma concentration for CPT-II, respectively The harmonic mean terminal half-lives for CPT-11, SN-38, and SN-38G were 7.1 hours, 13.4 hours, and 12.7 hours, respectively. No predictive correlation was observed between CPT-11 or SN-38 peak concentration or AUC and first-cycle diarrhea, neutropenia, nausea, or vomiting. Across the range of doses studied, mean CPT-11 clearance was 14.0 +/- 4.0 l/h/m2 and volume of distribution was 146 +/- 45.9 l/m2. CONCLUSIONS: When administered every two weeks, the recommended phase II starting dose of CPT-11 is 250 mg/m2 when given alone and 300 mg/m2 when supported by G-CSF. This every-two-week regimen offers a tolerable and active alternative to weekly or every-three-week single-agent CPT-11 therapy.

Matrix metalloproteinases: biologic activity and clinical implications.

Tumor progression is a complex, multistage process by which a normal cell undergoes genetic changes that result in phenotypic alterations and the acquisition of the ability to spread and colonize distant sites in the body. Although many factors regulate malignant tumor growth and spread, interactions between a tumor and its surrounding microenvironment result in the production of important protein products that are crucial to each step of tumor progression. The matrix metalloproteinases (MMPs) are a family of degradative enzymes with clear links to malignancy. These enzymes are associated with tumor cell invasion of the basement membrane and stroma, blood vessel penetration, and metastasis. They have more recently been implicated in primary and metastatic tumor growth and angiogenesis, and they may even have a role in tumor promotion. This review outlines our current understanding of the MMP family, including the association of particular MMPs with malignant phenotypes and the role of MMPs in specific steps of the metastatic cascade. As scientific understanding of the MMPs has advanced, therapeutic strategies that capitalize on blocking the enzymes have rapidly developed. The preclinical and clinical evolution of the synthetic MMP inhibitors (MMPIs) is also examined, with the discussion encompassing important methodologic issues associated with determining clinical efficacy of MMPIs and other novel therapeutic agents.

Efficacy of oxaliplatin in the treatment of colorectal cancer.

Colorectal cancer is one of the leading causes of cancer death. The mainstay of chemotherapy in colorectal cancer patients for the past 40 years has been fluorouracil (5-FU). Oxaliplatin (Eloxatin) is a novel platinum compound with promising activity in colorectal cancer. As a single agent, oxaliplatin has produced response rates of 12% to 24% in patients with previously untreated advanced colorectal cancer, and 10% to 11% in patients with relapsed or refractory advanced colorectal cancer. In phase II trials, oxaliplatin combined with 5-FU, with or without leucovorin, was associated with response rates of 60% and higher when used as front-line therapy, and when used in patients with relapsed or refractory advanced colorectal cancer, response rates ranged from 25% to 50%. In the front-line setting, two randomized trials of 5-FU and leucovorin, with or without oxaliplatin, demonstrated that the addition of oxaliplatin significantly increases response rate and time to tumor progression, but not survival, over 5-FU plus leucovorin alone. The reasons for this discrepancy are unclear, and several possibilities are being considered. Additional phase III trials are underway to clarify the contribution of oxaliplatin in the treatment of patients with locally advanced and metastatic colorectal cancer.

Topoisomerase I inhibitors in the treatment of colorectal cancer.

Over the past 10 years, a number of topoisomerase I inhibitors have entered into clinical trials and several of these have been evaluated in phase II and III studies to determine their activity in patients with advanced colorectal cancer. The most extensively studied of these has been irinotecan (CPT-II). In phase II trials in patients with colorectal cancer that was recurrent or refractory to 5-Ruorouracil (5-FU)based front-line therapy, response rates of 14% to 22% and median survival times of 8 to 10 months have been consistently reported by groups from Japan, Europe, and the United States using avariety of drug administration schedules Two recently reported phase III trials comparing CPT-II against infusional 5-FU or best supportive care demonstrated that CPT-II confers a survival advantage over either of the two other approaches. In front-line treatment of colorectal cancer, CPT-II produces response rates of 19% to 32% and median survival times of 11 to 12 months, figures quite similar to those achievable with bolus 5-FU and leucovorin. Further evaluation in the front-line setting has concentrated on the integration of CPT-II with 5-FU-based regimens. The role of other topoisomerase I inhibitors in colorectal cancer has been more difficult to characterize. Using a standard daily x 5 schedule, topotecan has little objective activity against relapsed or refractory colorectal cancer. Infusional topotecan appears more promising in the treatment of patients with advanced colorectal cancer. The development of an oral formulation of topotecan may make this approach more feasible and is likely to undergo dinical evaluation in the near future. Phase II evaluation of 9-aminocamptothecin (9-AC) has focused on infusional schedules of varying lengths Despite this, little antitumor activity has been observed against colorectal cancer. Other topoisomerase I inhibitors, such as DX-8951f and 9-nitrocamptothecin (9-NC, RFS2000), have not been formally tested in phase II trials against colorectal cancer. In summary, extensive evaluation of topoisomerase I inhibitors has identified a significant degree of variability in clinical activity in patients with advanced colorectal cancer. To date, only one topoisomerase I inhibitor, CPT-II, has demonstrated a level of activity sufficient for it to become an integral component of treatment for patients with 5-FU-refractory colorectal cancer. Current and future studies will focus on the development of front-line regimens combining CPT-II and 5-FU for treatment of patients with advanced-stage disease, moving topoisomerase I inhibitors into the adjuvant therapy setting, and developing combined modality regimens of surgery, radiation, and topoisomerase I inhibitors for patients with locally advanced colorectal cancer.

DNA topoisomerase I-targeting drugs as radiation sensitizers.

Combination chemoradiation, alone or as an adjuvant to surgery, has been shown to improve treatment outcomes in a number of human malignancies, but may be limited by normal tissue toxicities. A primary challenge in radiation oncology is the development of drugs that can selectively enhance the cytotoxicity of ionizing radiation against tumor cells. Mammalian DNA topoisomerase I is the major cytotoxic target of a number of newly developed anticancer drugs that have shown efficacy against solid tumors, including colon cancer, ovarian cancer, lung cancer, cancer of the head and neck, and pediatric cancers. Topoisomerase I-targeting drugs exert their cytotoxic effect by producing enzyme-mediated DNA damage, rather than by directly inhibiting enzyme catalytic activity. DNA topoisomerase I recently has been established as a biochemical mediator of radiosensitization in cultured mammalian cells by camptothecin derivatives. Interestingly, this sensitization appears to be schedule-dependent, cell cycle phase-specific, cell line-dependent, and not strictly dependent on drug cytotoxicity. Clinical chemoradiation trials using camptothecin derivatives are currently ongoing. Future studies aimed at better understanding the underlying mechanisms of molecular radiosensitization with topoisomerase I-targeting drugs are pivotal to the clinical application of these agents, as well as in guiding the development of more effective radiosensitizers.