Phase II and dose-escalation with or without granulocyte colony-stimulating factor study of 9-aminocamptothecin in relapsed and refractory lymphomas

Antitumor efficacy of colon-specific HPMA copolymer/9-aminocamptothecin conjugates in mice bearing human-colon carcinoma xenografts

The antitumor activity of a colon-specific N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer - 9-aminocamptothecin (9-AC) conjugate (P-9-AC) was assessed in orthotopic and subcutaneous animal (HT29 xenograft) tumor models. P-9-AC treatment of mice bearing orthotopic colon tumors, with a dose of 3 mg/kg of 9-AC equivalent every other day for 6 weeks, resulted in regression of tumors in 9 of 10 mice. A lower dose of P-9-AC (1.25 mg/kg of 9-AC equivalent) every other day for 8 weeks inhibited subcutaneous tumor growth in all mice. No liver metastases were observed. Colon-specific release of 9-AC from polymer conjugates enhanced antitumor activity and minimized the systemic toxicity.

Granulopoiesis-stimulating factors to prevent adverse effects in the treatment of malignant lymphoma

BACKGROUND

Granulopoiesis-stimulating factors, such as granulocyte-colony-stimulating factor (G-CSF) and granulocyte-macrophage-colony-stimulating factor (GM-CSF), are being used to prevent febrile neutropenia and infection in patients undergoing treatment for malignant lymphoma. The question of whether G-CSF and GM-CSF improve dose intensity, tumour response, and overall survival in this patient population has not been answered yet. Since the results from single studies are inconclusive, a systematic review was undertaken.

OBJECTIVES

To determine the effectiveness of G-CSF and GM-CSF in patients with malignant lymphoma with respect to preventing neutropenia, febrile neutropenia and infection; improving quality of life, adherence to treatment protocol, tumour response, freedom from treatment failure (FFTF) and overall survival (OS); and adverse effects.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, CancerLit, and other relevant literature databases; Internet databases of ongoing trials; and conference proceedings of the American Society of Clinical Oncology and the American Society of Hematology (1980 - 2007). We included full-text and abstract publications as well as unpublished data.

SELECTION CRITERIA

Randomised controlled trials comparing prophylaxis with G-CSF or GM-CSF versus placebo/no prophylaxis in adult patients with malignant lymphoma undergoing chemotherapy were included for review. Both study arms had to receive identical chemotherapy and supportive care.

DATA COLLECTION AND ANALYSIS

Trial eligibility and quality assessment, data extraction and analysis were done by two reviewers independently. Authors were contacted to obtain missing data.

MAIN RESULTS

We included 13 eligible randomised controlled trials with 2607 randomised patients. Compared with no prophylaxis, both G-CSF and GM-CSF did not improve overall survival (hazard ratio 0.97; 95% CI 0.87 to 1.09) or FFTF (hazard ratio 1.11; 95% CI 0.91 to 1.35). Prophylaxis significantly reduced the relative risk (RR) for severe neutropenia (RR 0.67; 95% confidence interval (CI) 0.60 to 0.73), febrile neutropenia (RR 0.74; 95% CI 0.62 to 0.89) and infection (RR 0.74; 95% CI 0.64 to 0.85). There was no evidence that either G-CSF or GM-CSF reduced the number of patients requiring intravenous antibiotics (RR 0.82; 95%CI 0.57 to 1.18); lowered infection related mortality (RR 0.93; 95% CI 0.51 to 1.71); or improved complete tumour response (RR 1.03; 95% CI 0.95 to 1.10).One study evaluated quality of life parameters and found no differences between the treatment groups.

AUTHORS' CONCLUSIONS

G-CSF and GM-CSF, when used as a prophylaxis in patients with malignant lymphoma undergoing conventional chemotherapy, reduce the risk of neutropenia, febrile neutropenia and infection. However, based on the randomised trials currently available, there is no evidence that either G-CSF or GM-CSF provide a significant advantage in terms of complete tumour response, FFTF or OS.

Phase II study of 9-aminocamptothecin in previously treated lymphomas: results of Cancer and Leukemia Group B 9551

PURPOSE

To evaluate the efficacy and toxicity of the topoisomerase I inhibitor, 9-aminocamptothecin (9-AC), in patients with relapsed lymphoma and to correlate 9-AC plasma concentrations with response and toxicity.

METHODS

Eligible patients had relapsed Hodgkin lymphoma (HL) treated with one or two prior regimens, low grade non-Hodgkin's lymphoma (NHL) treated with one or two prior regimens, or aggressive NHL treated with one prior regimen. The first nine patients received 9-AC dimethylacetamide 0.85 mg/m(2) per day intravenously over 72 h every 2 weeks and the remaining 27 patients received 9-AC/colloidal dispersion 1.1 mg/m(2) per day. Patients received a minimum of three cycles unless progression or intolerable toxicity occurred. Responding patients received two cycles past best response with a minimum of six cycles.

RESULTS

CALGB 9551 accrued 37 patients from April 1996 through October 2000; one patient with HD, 18 patients with indolent lymphoma, and 17 patients with aggressive lymphoma. The overall response rate was 17%, with response rates of 11% (2 partial responses) in patients with indolent histologies and 23% (1 complete response, 3 partial responses) in patients with aggressive histologies. The patient with HD did not respond. Response rates were similar for both drug formulations. The median remission duration for the six responders was 6.5 months, with one remission lasting longer than 12 months. Significant grade 3 and 4 toxicities included neutropenia (66%), anemia (31%), and thrombocytopenia (36%), with 20% of patients experiencing grade 3 or 4 infection. No treatment related deaths occurred. Steady state serum concentrations did not correlate with patient response or toxicity.

CONCLUSION

Single agent 9-AC has modest activity in aggressive non-Hodgkin's lymphomas.

Phase I trial of continuous infusion 9-aminocamptothecin in patients with advanced solid tumors: 21-day infusion is an active well-tolerated regimen

This study's objectives were to determine the maximum tolerated dose (MTD) of 9-aminocamptothecin (9-AC), given as a prolonged continuous infusion (CI) for 7-21 days, when formulated in dimethylacetamide/polyethylene glycol 400 (DMA) and then later as a colloidal dispersion (CD), and to determine the steady-state pharmacokinetics of 9-AC. Patients with solid tumors refractory to standard therapy were enrolled on this study. Total dose/cycle of 9-AC/DMA was initially escalated by duration (7-21 days), while keeping the dose rate constant at 6.2 microg/m/h (1.04-3.12 mg/m/4-week cycle). Then, the dose rate was escalated from 6.2 to 21.1 microg/m/h (3.12-10.6 mg/m/4-week cycle) while keeping the infusion duration constant at 21 days. CD formulation was escalated from 14.1 to 25 microg/m/h (7.11-12.60 mg/m/4-week cycle) while keeping the infusion duration constant at 21 days and then escalated from 28.1 to 37.5 microg/m/h (9.44-12.60 mg/m/3-week cycle) while keeping the infusion duration constant at 14 days. Sixty-two patients were evaluable for toxicity; 61 received prior chemotherapy (median 3 regimens/patient). No consistent dose-limiting toxicity (DLT) was encountered with the DMA formulation until dose level 10.60 mg/m/cycle, when two patients experienced DLTs. With the 21-day CD formulation, the MTD was 12.60 mg/m/cycle with three DLTs out of five patients. When 9-AC was given on the 14-day schedule, DLT was seen at 9.44, 11.20 and 12.60 mg/m/cycle, with consistent DLT at the two highest dose levels. All DLTs for both formulations were grade 4 hematologic toxicities (neutropenia and/or thrombocytopenia), while non-hematologic toxicities were relatively mild (including gastrointestinal toxicities and fatigue). One patient with ovarian cancer had a complete response and three had partial responses (PRs). One patient each with non-Hodgkin's lymphoma and cancer of unknown primary had a PR. Pharmacokinetic studies of both formulations of 9-AC revealed a linear relationship between increasing plasma 9-AC lactone concentration and dose. The median plasma 9-AC lactone concentration for 9-AC/CD was approximately twice that achieved by 9-AC/DMA for the same dose level. Both 9-AC formulations, given as a 21-day CI, were well tolerated with dose-limiting myelosupression at the MTD. This dose intensity exceeds that of other 9-AC phase I/II schedules. The recommended phase II dose (RPTD) is 9.42 mg/m/4-week cycle, given as a 21-day infusion. The 14-day schedule of 9-AC/CD was equally myelosuppressive with the RPTD of 9.44 mg/m/3-week cycle, although two heavily pre-treated patients (one with pelvic radiotherapy) could not tolerate this dose. Objective responses were observed in six out of 57 heavily pre-treated patients, most of which had ovarian cancer.

Systemic chemotherapy for the treatment of mycosis fungoides and Sezary syndrome

The treatment of mycosis fungoides and Sézary syndrome is unique. The treatments of choice are highly stage-and practitioner-dependent. For early stage patients, treatment with palliative topical therapies is often adequate to yield excellent, high-quality and durable responses. For the more advanced stages, systemic approaches are more appropriate, either alone or in combination, to palliate patients. There is still little convincing evidence from randomized trials that any single approach is favorable for improving survival. Many practitioners believe the disease can be controlled with the host immune system, but there again is little scientific support for this conclusion. It has been hypothesized that some of our therapies work through this mechanism, such as photopheresis and perhaps even psoralen and ultraviolet A. Unfortunately, even the use of biologic response modifiers, such as interferon and the interleukins, is not absolutely supportive of an active role for immune surveillance since these agents have been shown to have cytotoxic and differentiating effects. Because of the above, many practitioners have actively discouraged the use of chemotherapy because it may impair the host immune system; certainly, the purine analogs would fall into this category. However, there is little evidence supporting significant immune effects for other chemotherapeutics, and clearly, the responses seen would support their use in appropriate patients. As the present authors will detail in this paper, the advances in understanding cancer biology and mechanisms of resistance should, in the future, lead to optimal selection of agents that are predicted to be optimally active, limiting the toxicity and waste associated with ineffective drug usage.

Current trends in large cell lymphoma

For the last decade, cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) has been the best available standard of care for aggressive non-Hodgkin's lymphoma (NHL), based on equivalent therapeutic results with other multiagent chemotherapy accompanied by lower costs and lesser toxicity. However, only 40-45% of these patients are cured with CHOP. New treatment strategies have been employed, including the addition of Rituximab to CHOP in elderly patients; dose escalation using granulocyte-colony-stimulating factor; overcoming the multidrug resistance phenotype with infusional chemotherapeutic regimens and use of some newer agents. Furthermore, the International Prognostic Factor index (IPI) has permitted identification of subsets of patients with large variations in prognosis, allowing prognosis specific therapy to be tested. There is now accumulating evidence that the clinical behavior of certain NHL can be profiled by the expression of certain molecular markers, which will undoubtedly play a role in the development of new prognostic models that may refine our ability to identify poor-risk patients. Regardless, there is still significant opportunity for improving survival in large cell lymphomas.

Intravenous administration of 9-aminocamptothecin to dogs with lymphoma

A colloidal dispersion formulation of 9-aminocamptothecin (9-AC) was administered intravenously to 10 dogs with previously untreated, spontaneously occurring, multicentric lymphoma. The dogs received a 72-h infusion of 9-AC at a rate of 46.5-51.25 microg m(-2) h(-1) (total dose range 3.35-3.69 mg m(-2)). This dose range was associated with myelosuppression, consisting principally of neutropenia with a nadir at 7 days following the start of infusion. Neutropenia and thrombocytopenia were the most common toxicoses and are most likely to be dose-limiting toxicities; low-grade gastrointestinal signs were rarely seen. Concentrations of 9-AC lactone, as well as clinical toxicities, compare favourably with those found in humans. Tumour responses were seen in all treated dogs. Response to other chemotherapy, following cessation of 9-AC treatment, was not obviously compromised even in dogs clinically resistant to 9-AC. 9-AC is a novel treatment drug for canine lymphoma, which appears to show great promise.

Phase II study of sequential topotecan and etoposide in patients with intermediate grade non-Hodgkin's lymphoma: a National Cancer Institute of Canada Clinical Trials Group study

Preliminary results indicate that inhibitors of the nuclear enzyme topoisomerase (topo) I, such as topotecan, may be active in non-Hodgkin's lymphoma (NHL). Pre-clinical studies have shown sequential administration of a topo I and II inhibitor has supra-additive anti-tumor effects in some model systems, and that greater cytotoxicity occurs if the topo I inhibitor is given first. We enrolled, 22 eligible patients with relapsed or refractory intermediate grade NHL in a phase II study ofsequential administration of topotecan 1.25 mg/m2 days 1-5 and etoposide 50 mg po b.i.d. days 6-12, every 28 days without G-CSF. Most patients had diffuse large B-cell lymphoma and all had received only one prior regimen (CHOP, 20 patients, or equivalent, 2 patients). Patients with stable or responding disease were allowed to proceed to high-dose therapy and autologous stem-cell transplant after 2 cycles of therapy. The 22 patients received a total of 62 cycles of topotecan + etoposide (median 2, range 1-6), and 4/22 completed all six planned cycles. Hematologic toxicity was significant and resulted in incomplete etoposide dosing in half of all cycles in 16/22 patients. Nineteen of twenty-two patients had grade 3/4 neutropenia, 12 had grade 3/4 thrombocytopenia, and 6 grade 3/4 anemia. Eleven patients had at least one episode of febrile neutropenia or had documented infection. Non-hematologic toxicity was mild. Four patients had a partial response (PR) (18.2%), nine had stable disease and seven progressed; three patients with stable disease went on to ABMT. The combination of topotecan and etoposide as given in this study has modest activity in relapsed/refractory aggressive histology NHL, and produces marked myelosuppression. Other doses and schedules combining topo I and II inhibitors, or topo I inhibitors with alkylating agents, should be explored with the addition of hematopoietic growth factors in this patient population.

A phase II study of topotecan in non-Hodgkin's lymphoma: an Ohio State University phase II research consortium study

PURPOSE

This multicenter phase II trial evaluated the efficacy and toxicity of the topoisomerase I inhibitor topotecan (TPT, 9-dimethylaminomethyl-10-hydroxycamptothecin) in patients with refractory or relapsing non-Hodgkin's lymphoma.

PATIENTS AND METHODS

Thirty-two patients with previously treated non-Hodgkin's lymphoma were accrued in this study from June 1992 to June 1997. Patients were eligible if they had measurable disease and had received two or less chemotherapy treatments for indolent lymphoma or no more than one treatment for aggressive lymphoma. Nineteen patients with aggressive lymphoma including seven with transformed indolent disease and 11 patients with indolent disease were treated. Two additional patients had both indolent and aggressive lymphoma in the bone marrow and lymph nodes at entrance into the study. Topotecan was administered as a 30-min infusion at a dose of 1.25 mg/m2 for five days and repeated at three week intervals.

RESULTS

Thirty-two patients were evaluable for toxicity and 29 patients were evaluable for response. There were five objective responses including two complete remissions and three partial remissions (17%; CI 4-30%). Four of the five responders had aggressive disease and had been responsive to prior chemotherapy. The duration of remissions were short, lasting a median of 2 months (range 2-52 months). The major toxicity seen was myelosuppression with 28 of the 32 patients having grade three or greater granulocytopenia.

CONCLUSION

Topotecan given as a five day 30 min infusion at a dose of 1.25 mg/m2 has modest activity in previously treated non-Hodgkin's lymphoma as compared to other active agents.

A literature review of single agent treatment of multiply relapsed aggressive non-Hodgkin's lymphoma

To analyze the available literature describing the treatment of relapsed aggressive non-Hodgkin's lymphoma (NHL) with single-agent chemotherapies, several comprehensive electronic and manual inspections of the literature were performed for the period from 1966 to the present. Each paper was examined to capture the following data: study type; patient demographics and characteristics; study endpoints, including responses, and method used to evaluate response; toxicities, and the power of the study. A wide variety of single-agent protocols continue to be studied, indicating no currently accepted standard therapy in this patient population. Reported response rates varied between 0 and 67%. The majority of trials were small, uncontrolled studies that used widely varying inclusion/exclusion criteria and had limited reporting of histology, response, prior treatments, and other key parameters. We were able to find only four agents, etoposide, vincristine, vinorelbine and possibly rituximab, with sufficient reproducible evidence to suggest greater than 30% activity (CR + PR rate) when given to patients with second or greater relapse of aggressive NHL. Consequently, the usefulness of the agents in these reports remains to be established in larger trials with more detailed reporting. The advantages that would be brought by an active non-myelosuppressive agent for patients having this condition emerge clearly from this review.

Phase II trial of 9-aminocamptothecin as a 72-h infusion in cutaneous T-cell lymphoma

PURPOSE

To evaluate the role of 9-aminocamptothecin (9-AC), a synthetic camptothecin analog, in advanced cutaneous T-cell lymphoma (CTCL).

METHODS

Eligible patients had stage IIB-IV CTCL. 9-AC was infused over 72 h at a dose of 1,100 microg/m2 per day (approximately 46 microg/m2/h) every 2 weeks, with granulocyte-colony stimulating factor (G-CSF) support.

RESULTS

Twelve patients received a total of 30 cycles of 9-AC. Nine patients had stage IV disease, 5 patients had circulating Sezary cells, and 2 patients had evidence of tranformation to a large cell lymphoma. Most of the patients were heavily pretreated: 10 had received prior chemotherapy (83%), 5 of whom had received 2 or more prior regimens, including a patient who had received high-dose chemotherapy, and 7 had previously received total-skin electron beam therapy. The study was prematurely terminated due to substantial toxicity. Six patients (50%) developed an indwelling central venous catheter-related infection, 5 during a period of neutropenia. Three patients died due to sepsis 4-8 weeks after their last 9-AC treatment. Two of these patients had a previous history of bacterial sepsis. Four patients (33%) developed grade IV thrombocytopenia. Two partial responses were observed (response rate 17%), but the duration of response was brief, 4-8 weeks.

CONCLUSION

9-AC at this schedule and route of administration had activity but resulted in an unacceptable rate of complicated neutropenia and septic deaths in heavily pretreated patients with advanced CTCL who are susceptible to catheter-related infections.

Camptothecins

Camptothecin analogues and derivatives appear to exert their antitumour activity by binding to topoisomerase I and have shown significant activity against a broad range of tumours. In general, camptothecins are not substrates for either the multidrug-resistance P-glycoprotein or the multidrug-resistance-associated protein (MRP). Because of manageable toxicity and encouraging activity against solid tumours, camptothecins offer promise in the clinical management of human tumours. This review illustrates the proposed mechanism(s) of action of camptothecins and presents a concise overview of current camptothecin therapy, including irinotecan and topotecan, and novel analogues undergoing clinical trails, such as exatecan (DX-8951f), IDEC-132 (9-aminocamptothecin), rubitecan (9-nitrocamptothecin), lurtotecan (GI-147211C), and the recently developed homocamptothecins diflomotecan (BN-80915) and BN-80927.

New drug development in non-Hodgkin lymphomas

The non-Hodgkin lymphomas (NHL) are characterized by initial responsiveness to a variety of chemotherapeutic regimens. Nevertheless, most patients progress and die from their disease. A number of new agents with unique mechanisms of action are in clinical development. Agents that are currently considered to be the most promising include those that induce apoptosis; those that interfere with cell cycling, tumor-associated angiogenesis, farnesylation of the Ras gene, and histone deacetylase; and those that inhibit the proteasome, among others. Increasing insights into the differences between tumors and among patients will lead to more individualized therapeutic strategies using agents directed at specific genetic and immunologic targets. More rapid accrual to high-quality clinical studies will facilitate dissemination of new agents to patients and lead to an increased cure rate for NHL.

The clinical development of 9-aminocamptothecin

9-Aminocamptothecin (9-AC) is a topoisomerase I-targeting agent first synthesized by Wani and Wall in 1986. Because of its potent in vitro effects and promising preclinical activity in colorectal cancer animal models, it was designated a high-priority compound for further drug development by the NCI. In 1993, 9-AC first entered clinical trials as a 72-hour intravenous (i.v.) infusion. Predictable myelosuppression was the major dose-limiting toxicity, and pharmacokinetic studies showed a relatively short plasma half-life and unstable lactone ring. Unfortunately, phase II studies using this schedule showed minimal or no activity in tumors such as colorectal and lung cancer. Modest activity was observed in ovarian cancer and in refractory lymphomas. Efforts to improve systemic drug exposure by utilizing alternative schedules of administration of 9-AC such as prolonged, continuous intravenous infusions have also been tested. However, phase II studies of 120-hour weekly infusions of 9-AC have not shown improved activity against solid tumors such as colorectal cancer. More recently, a daily times 5 days i.v. administration schedule has been tested. Currently, further development of intravenously administered 9-AC for the treatment of colorectal cancer is not promising. Thus, topotecan and irinotecan remain the only two successfully developed topoisomerase I-targeting drugs in the United States. This experience with 9-AC raises important questions regarding how to best select new topoisomerase I-targeting drugs for future clinical development.

Modulation of camptothecin analogs in the treatment of cancer: a review

The topoisomerase I inhibitors reviewed in this paper are all semisynthetic analogs of camptothecin (CPT). Modulation of this intranuclear enzyme translates clinically in to antitumor activity against a broad spectrum of tumors and is therefore the subject of numerous investigations. We present preclinical and clinical data on CPT analogs that are already being used in clinical practice [i.e. topotecan and irinotecan (CPT-11)] or are currently in clinical development (e.g. 9-aminocamptothecin, 9-nitrocamptotecin, lurtotecan, DX 8951f and BN 80915), as well as drugs that are still only developed in a preclinical setting (silatecans, polymer-bound derivates). A variety of different strategies is being used to modulate the systemic delivery of this class of agents, frequently in order to increase antitumor activity and/or reduce experienced side effects. Three principal approaches are discussed, including: (i) pharmaceutical modulation of formulation vehicles, structural alterations and the search for more water-soluble prodrugs, (ii) modulation of routes of administration and considerations on infusion duration, and (iii) both pharmacodynamic and pharmacokinetic biomodulation.

Role of a doxorubicin-containing regimen in relapsed and resistant lymphomas: an 8-year follow-up study of EPOCH

PURPOSE

Curative up-front regimens for non-Hodgkin's lymphomas contain doxorubicin, vincristine, and cyclophosphamide, whereas salvage regimens generally contain non-cross-resistant agents. We hypothesized that up-front agents may be highly effective for salvage and developed an infusional regimen based on in vitro evidence of increased efficacy.

PATIENTS AND METHODS

A prospective phase II study of etoposide, vincristine, and doxorubicin over 96 hours with bolus cyclophosphamide and oral prednisone (EPOCH) was performed in 131 patients with relapsed or resistant lymphoma.

RESULTS

Seventy-nine percent of patients had aggressive histologies, 46% were considered high risk by the International Prognostic Index, and 34% had resistant disease. Eighty-eight percent of patients had received at least four of the agents in EPOCH, and 94% had received doxorubicin. In 125 assessable patients, 29 (24%) achieved complete responses and 60 (50%) achieved partial responses. Among 42 patients with resistant disease, 57% responded, and in 28 patients with relapsed aggressive de novo lymphomas, 89% responded with 54% complete responses. With a median follow-up of 76 months, the overall and event-free survivals (EFS) were 17.5 and 7 months, respectively. In 33 patients with sensitive aggressive disease who did not receive stem-cell transplantation, EFS was 19% at 36 months. Toxicity was primarily hematologic, with an 18% incidence of febrile neutropenia. No clinically significant cardiac toxicity was observed, despite no maximum cumulative doxorubicin dose.

CONCLUSION

EPOCH is highly effective in patients who had previously received most/all of the same drugs and produces durable remissions in curable subtypes. Salvage regimens need not contain non-cross-resistant agents, and infusional schedules may partially reverse drug resistance and reduce toxicity.

Treatment advances in non-Hodgkin's lymphoma

Non-Hodgkin's lymphomas (NHL) encompass a heterogeneous group of lymphoid malignancies with varying natural histories and prognoses. Recent classifications for NHL have defined distinct lymphoma entities based on morphology, immunophenotype, genetic features, clonal cell lineage and clinical features. These new, more precise classifications and characterizations of NHL will be essential in developing new targeted therapies. However, for this brief review, we will continue describe NHL primarily as indolent or aggressive. Treatment options for patients with indolent, but generally incurable, lymphomas include a 'watch and wait' approach, single agent alkylators, nucleoside analogues, combination chemotherapy, immunotherapy with monoclonal antibodies, radiolabelled monoclonal antibodies, or interferon (IFN). Vaccine therapy for indolent lymphomas is currently under intense investigation. For aggressive lymphomas, combination chemotherapy remains the standard of care. Major advances in the management of aggressive lymphomas include validation of the international prognostic index and clarification of the role of high-dose therapy with bone marrow or stem cell transplant in patients with relapsed aggressive lymphomas. Multiple randomised pilot trials of high dose therapy as initial therapy for aggressive lymphomas have shown conflicting results and await confirmatory studies.

Gemcitabine as a single agent in the treatment of relapsed or refractory aggressive non-Hodgkin's lymphoma

PURPOSE

A multicenter phase II trial was conducted to evaluate the efficacy and toxicity of gemcitabine in patients with relapsed or refractory aggressive non-Hodgkin's lymphomas (NHL).

PATIENTS AND METHODS

Thirty-one patients with B-cell intermediate or high-grade NHL (Working Formulation) were enrolled onto the study. The median age was 61 years, with a Karnofsky performance status of </= 80% in 65% of patients. Forty-eight percent had stage III or IV (Ann Arbor Classification) at study entry. Pretreatment consisted of one, two, or three chemotherapeutic regimens in nine, 11, and 11 patients, respectively. Gemcitabine 1,250 mg/m(2) was administered intravenously over 30 minutes on days 1, 8, and 15 of a 28-day schedule.

RESULTS

Thirty patients were assessable for efficacy, and 31 were assessable for toxicity. No complete responses were observed, but six patients showed a partial response, 11 stable disease, and 13 progressive disease. The overall response rate was 20% (95% confidence interval, 8% to 39%) for assessable patients and 19% (95% confidence interval, 8% to 34%) for the intent-to-treat analysis. The median duration of partial response was 6 months (range, 3.7 to 15+ months). Nonhematologic World Health Organization grade 3 toxicity included hepatic toxicity in four patients and infection in two. Hematologic toxicity was observed as grade 3 anemia in three patients, grade 3 leukopenia in two patients, grade 3/4 neutropenia in two patients, and grade 3/4 thrombocytopenia in six patients.

CONCLUSION

The present schedule of gemcitabine displays modest efficacy and mild toxicity in pretreated aggressive NHL.

Topoisomerase enzymes as drug targets

DNA topoisomerases catalyze changes in the topology of DNA. Recently, other functions have also been reported for these enzymes. For example, topoisomerase I participates in transcription by RNA polymerases I, II, and III, and also has a kinase activity. Topoisomerase I binds directly to at least two helicases, nucleolin and SV40 T antigen, and mechanistic studies show that T antigen alters the function of topoisomerase I. Additional protein and nucleotide interactions for both topoisomerases I and II suggest that each protein is multifunctional. It may be that the multifunctional nature of these enzymes is the basis for the antitumor activity seen with inhibitors of these enzymes. Clinical trials with combinations of CPT-11 and 5-fluorouracil for the treatment of colon cancer, and preclinical studies with CPT-11 and vincristine are particularly encouraging. Protracted schedules of administration of topoisomerase inhibitors will likely have greater antitumor effect than more concentrated, higher dose exposures, but a systematic determination of optimal schedules of administration is needed.

Design and synthesis of water-soluble glucuronide derivatives of camptothecin for cancer prodrug monotherapy and antibody-directed enzyme prodrug therapy (ADEPT)

Glucuronide prodrugs of 9-aminocamptothecin were synthesized. Prodrug 4, in which 9-aminocamptothecin was connected to glucuronic acid by an aromatic spacer via a carbamate linkage, was stable in both aqueous solution and human plasma. Prodrug 4 and its potassium salt 12 were 20-80-fold less toxic than 9-aminocamptothecin to human tumor cell lines. The simultaneous addition of beta-glucuronidase and 4 or 12 to tumor cells resulted in a cytotoxic effect equal to that of 9-aminocamptothecin alone. Prodrugs 4 and 12 were over 80 and 4000 times more soluble than 9-aminocamptothecin in aqueous solutions at pH 4.0, respectively. Compounds 4 and 12 may be useful for prodrug monotherapy of tumors that accumulate extracellular lysosomal beta-glucuronidase as well as for antibody-directed enzyme prodrug therapy (ADEPT) of cancer.

Hodgkin's disease and non-Hodgkin's lymphoma

The development of new classification schemes and prognostic analyses for lymphomas has helped to identify patients at high risk for relapse who may benefit from intensification of primary therapy. Conventional salvage therapy for relapsed follicular or low-grade lymphomas now includes monoclonal antibody therapy. The combination of chemotherapy and monoclonal antibody therapy may improve outcomes for patients with advanced-stage aggressive non-Hodgkin's lymphomas. Confirmatory randomized trials are now in progress. Therapy for Hodgkin's disease continues to evolve toward the most efficacious programs, which also minimize the long-term probability of toxicity. The combination of high-dose chemotherapy and stem cell transplantation is probably the most effective therapy for patients with relapsed or refractory Hodgkin's disease.