Chemotherapy with irinotecan (CPT-11), a topoisomerase-I inhibitor, for refractory and relapsed non-Hodgkin's lymphoma

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

Chem-seq permits identification of genomic targets of drugs against androgen receptor regulation selected by functional phenotypic screens

Understanding the mechanisms by which compounds discovered using cell-based phenotypic screening strategies might exert their effects would be highly augmented by new approaches exploring their potential interactions with the genome. For example, altered androgen receptor (AR) transcriptional programs, including castration resistance and subsequent chromosomal translocations, play key roles in prostate cancer pathological progression, making the quest for identification of new therapeutic agents and an understanding of their actions a continued priority. Here we report an approach that has permitted us to uncover the sites and mechanisms of action of a drug, referred to as "SD70," initially identified by phenotypic screening for inhibitors of ligand and genotoxic stress-induced translocations in prostate cancer cells. Based on synthesis of a derivatized form of SD70 that permits its application for a ChIP-sequencing-like approach, referred to as "Chem-seq," we were next able to efficiently map the genome-wide binding locations of this small molecule, revealing that it largely colocalized with AR on regulatory enhancers. Based on these observations, we performed the appropriate global analyses to ascertain that SD70 inhibits the androgen-dependent AR program, and prostate cancer cell growth, acting, at least in part, by functionally inhibiting the Jumonji domain-containing demethylase, KDM4C. Global location of candidate drugs represents a powerful strategy for new drug development by mapping genome-wide location of small molecules, a powerful adjunct to contemporary drug development strategies.

Intercepting the synthesis of triazine dendrimers with nucleophilic pharmacophores: a general strategy toward drug delivery vehicles

The camptothecin ester of isonipecotic acid is installed on a triazine dendrimer intermediate obtained through an iterative, scalable route to ultimately yield cationic and PEGylated targets with activities in cell culture comparable to free drug.

Preclinical results of camptothecin-polymer conjugate (IT-101) in multiple human lymphoma xenograft models

PURPOSE

Camptothecin (CPT) has potent broad-spectrum antitumor activity by inhibiting type I DNA topoisomerase (DNA topo I). It has not been used clinically because it is water-insoluble and highly toxic. As a result, irinotecan (CPT-11), a water-soluble analogue of CPT, has been developed and used as salvage chemotherapy in patients with relapsed/refractory lymphoma, but with only modest activity. Recently, we have developed a cyclodextrin-based polymer conjugate of 20-(S)-CPT (IT-101). In this study, we evaluated the preclinical antilymphoma efficacy of IT-101 as compared with CPT-11.

EXPERIMENTAL DESIGN

We determined an in vitro cytotoxicity of IT-101, CPT-11, and their metabolites against multiple human lymphoma cell lines. In human lymphoma xenografts, the pharmacokinetics, inhibitions of tumor DNA topo I catalytic activity, and antilymphoma activities of these compounds were evaluated.

RESULTS

IT-101 and CPT had very high in vitro cytotoxicity against all lymphoma cell lines tested. As compared with CPT-11 and SN-38, IT-101 and CPT had longer release kinetics and significantly inhibit higher tumor DNA topo I catalytic activities. Furthermore, IT-101 showed significantly prolonged the survival of animals bearing s.c. and disseminated human xenografts when compared with CPT-11 at its maximum tolerated dose in mice.

CONCLUSIONS

The promising present results provide the basis for a phase I clinical trial in patients with relapsed/refractory lymphoma.

UGT1A1 promoter genotype correlates with SN-38 pharmacokinetics, but not severe toxicity in patients receiving low-dose irinotecan

PURPOSE

To study the association between UDP-glucuronosyltransferase 1A1 (UGT1A1) genotypes and severe toxicity as well as irinotecan disposition in pediatric patients with solid tumors receiving low-dose, protracted irinotecan (15 to 75 mg/m2 daily for 5 days for 2 consecutive weeks).

PATIENTS AND METHODS

Seventy-four patients on five institutional clinical trials received irinotecan (15 to 75 mg/m2) daily intravenously or orally for 5 days for 2 consecutive weeks. Genomic DNA was genotyped for UGT1A1*28, and patients were designated as 6/6, 6/7, or 7/7 depending on the number of TA repeats in the UGT1A1 promoter region. Patients were evaluated for gastrointestinal and hematologic toxicity, as well as baseline and maximal serum bilirubin levels. Toxicity and pharmacokinetic results were evaluated during courses 1 and 2 of irinotecan therapy.

RESULTS

The frequencies of 6/6, 6/7, and 7/7 genotypes were 27 (36.5%), 36 (48.6%), and 9 (12.2%) of 74 patients, respectively. Patients with 7/7 genotype had a statistically greater baseline total bilirubin than patients with 6/6 or 6/7 genotype (P = .005). UGT1A1*28 genotype was not associated with grade 3 and 4 neutropenia (P = .21 for course 1; P = .23 for course 2) or diarrhea (P = .176 for course 1; P = .87 for course 2). However, patients with the 7/7 genotype tended to have higher SN-38 area under the plasma time-concentration curve (AUC) values and lower SN-38G/SN-38 AUC ratios.

CONCLUSION

Severe toxicity was not increased in pediatric patients with the 7/7 genotype when treated with a low-dose protracted schedule of irinotecan. Therefore, UGT1A1 genotyping is not a useful prognostic indicator of severe toxicity for patients treated with this irinotecan dosage and schedule.

Phase I Study of the Combination of Irinotecan Hydrochloride, Carboplatin, and Dexamethasone for the Treatment of Relapsed or Refractory Malignant Lymphoma

A phase I study of irinotecan hydrochloride (CPT-11), carboplatin, and dexamethasone treatment in 7 patients with relapsed lymphoma and 7 patients with refractory lymphoma was conducted to evaluate the maximal tolerated dose. The 6 female and 8 male patients had a median age of 63 years (range, 45-73 years), a median performance status of 0 (range, 0-2), and a median disease stage of IV. This study included patients with diffuse large B-cell lymphoma (n = 5), adult T-cell leukemia/lymphoma (n = 2), mantle cell lymphoma (n = 2), follicular lymphoma (n = 2), angioimmunoblastic T-cell lymphoma (n = 1), anaplastic large cell lymphoma (n = 1), and Hodgkin's lymphoma (n = 1). All patients had received anthracycline-containing combination chemotherapy prior to this therapy. The starting dosage of CPT-11 was 15 mg/m2 per day (days 1-3 and 8-10), and dosage-escalation increments of 5 mg/m2 per day were planned, with fixed dosages of carboplatin (250 mg/m2 per day, day 1) and dexamethasone (40 mg/body, days 1-3 and days 8-10). Five patients were enrolled at level 1, 3 at level 2, 4 at level 3, and 2 at level 4. Ten patients (71%) and 11 patients (79%) experienced grade 3 or 4 hematologic toxicities of leukocytopenia and neutropenia, respectively. Three patients (29%) and 9 patients (64%) experienced grade 3 or 4 thrombocytopenia and anemia, respectively. Two patients who received 30 mg/m2 (level 4) of CPT-11 developed sepsis. We concluded that the recommended dose of CPT-11 with carboplatin and dexamethasone is 25 mg/m2. No deaths were related to this chemotherapy, and no patient developed liver dysfunction. The overall response rate was 36%. We conclude that the combination therapy of CPT-11, carboplatin, and dexamthasone is effective as salvage therapy but that the duration of response is too short.