Preclinical activity of P276-00, a novel small-molecule cyclin-dependent kinase inhibitor in the therapy of multiple myeloma.

Cyclin D dysregulation and overexpression is noted in the majority of multiple myeloma (MM) patients, suggesting its critical role in MM pathogenesis. Here, we sought to identify the effects of targeting cyclin D in MM. We first confirmed cyclin D mRNA overexpression in 42 of 64 (65%) patient plasma cells. Silencing cyclin D1 resulted in >50% apoptotic cell death suggesting its validity as a potential therapeutic target. We next evaluated P276-00, a clinical-grade small-molecule cyclin-dependent kinase inhibitor as a way to target the cyclins. P276-00 resulted in dose-dependent cytotoxicity in MM cells. Cell-cycle analysis confirmed either growth arrest or caspase-dependent apoptosis; this was preceded by inhibition of Rb-1 phosphorylation with associated downregulation of a range of cyclins suggesting a regulatory role of P276-00 in cell-cycle progression through broad activity. Proliferative stimuli such as interleukin-6, insulin-like growth factor-1 and bone-marrow stromal cell adherence induced cyclins; P276-00 overcame these growth, survival and drug resistance signals. Because the cyclins are substrates of proteasome degradation, combination studies with bortezomib resulted in synergism. Finally, in vivo efficacy of P276-00 was confirmed in an MM xenograft model. These studies form the basis of an ongoing phase I study in the treatment of relapsed/refractory MM.

Complementary, alternative, integrative, or unconventional medicine?

Shortly before his death in 1995, Kenneth B. Schwartz, a cancer patient at Massachusetts General Hospital (MGH), founded the Kenneth B. Schwartz Center. The Schwartz Center is a non-profit organization dedicated to supporting and advancing compassionate health care delivery, which provides hope to the patient, support to caregivers, and sustenance to the healing process. The center sponsors the Schwartz Center Rounds, a monthly multidisciplinary forum where caregivers reflect on important psychosocial issues faced by patients, their families, and their caregivers, and gain insight and support from fellow staff members. Interest in complementary and alternative medicine (CAM) has grown exponentially in the past decade, fueled by Internet marketing, dissatisfaction with mainstream medicine, and a desire for patients to be actively involved in their health care. There is a large discordance between physician estimates and reported prevalence of CAM use. Many patients do not disclose their practices mainly because they believe CAM falls outside the rubric of conventional medicine or because physicians do not ask. Concern about drug interactions and adverse effects are compounded by a lack of Food and Drug Administration regulation. Physicians need to be informed about CAM and be attuned to the psychosocial needs of patients.

Losing God.

Shortly before his death in 1995, Kenneth B. Schwartz, a cancer patient at Massachusetts General Hospital (MGH), founded the Kenneth B. Schwartz Center. The Schwartz Center is a non-profit organization dedicated to supporting and advancing compassionate health care delivery, which provides hope to the patient, support to caregivers, and sustenance to the healing process. The center sponsors the Schwartz Center Rounds, a monthly multidisciplinary forum where caregivers reflect on important psychosocial issues faced by patients, their families, and their caregivers, and gain insight and support from fellow staff members. Nebulous language, distrust, and dogma confound spiritual aspects of cancer care. However, existential well being is an important determinant of quality of life: finding meaning and purpose make suffering more tolerable. The case presented is of a patient who experienced "losing God" as a Hodgkin's disease survivor with metastatic prostate cancer and severe coronary artery disease. His caregivers were able to provide the sense of community in which he could re-establish his faith. Health care providers do not have to be religious in order to help patients to deal with a spiritual crisis. The clinical skills of compassion need to be deployed to diagnose and respond to spiritual suffering. Acknowledging and addressing anger or guilt, common sources of suffering, are essential to adjustment. Simply being there for the patient and being open to their hurt can help resolve their spiritual crisis, a responsibility that is shared by the whole health care team.

The role of thymidylate synthase expression in prognosis and outcome of adjuvant chemotherapy in patients with rectal cancer.

PURPOSE: We assessed the prognostic importance of the level of thymidylate synthase (TS) expression in patients with primary rectal cancer and whether, for Dukes' B and C cancer patients, the benefit of chemotherapy was associated with TS expression. PATIENTS AND METHODS: The level of TS expression in the primary rectal cancers of 294 of 801 patients enrolled on protocol R-01 of the National Surgical Adjuvant Breast and Bowel Project (NSABP) was immunohistochemically assessed with the monoclonal antibody TS 106. RESULTS: Forty-nine percent of patients whose tumors had low TS levels (n = 91) were disease free at 5 years compared with 27% of patients with high levels of TS (n = 203; P < .01). Moreover, 60% of patients with low TS levels were alive after 5 years compared with 40% of patients with high TS levels (P < .01). The level of TS protein was significantly associated with Dukes' stage (P < .01); patients with a more advanced Dukes' stage had a significantly higher level of TS. The level of TS expression remained prognostic for both disease-free survival (P < .01) and survival (P < .05) independent of Dukes' stage and other pathologic characteristics evaluated. Thirty-eight percent and 54% of patients with high TS levels (n = 71) were disease free and alive, respectively, after 5 years when treated with chemotherapy, compared with 17% and 31%, respectively, of similar patients when treated with surgery alone (n = 64) (P < .01). No difference was noted in disease-free survival (P = .46) or survival (P = .43) in patients with low TS levels. CONCLUSION: The expression of TS is an important independent prognosticator of disease-free survival and survival in patients with rectal cancer. Adjuvant fluorouracil (5-FU)-based chemotherapy demonstrated significant improvement in disease-free and overall survival for patients with high TS levels. Prospective studies measuring TS levels will be needed to understand further the role of TS as a prognosticator of survival and chemotherapeutic benefit.

The National Cancer Institute: cancer drug discovery and development program.

The discovery and development of novel therapeutic products for the treatment of malignancy is vitally important to those physicians responsible for the management of cancer patients. A description of the ongoing efforts at the National Cancer Institute (NCI) is intended to provide insight into those complex processes necessary to accomplish this mission. An update on the NCI's revised cancer screen is accompanied by a brief summary of those new agents scheduled to be entered into clinical investigation in the near future. The tremendous potential advantages and challenges associated with the use of a molecular approach to cancer drug design are discussed. Despite the differences of opinion that may exist regarding the optimal strategies for accomplishing the mission, there is no disagreement regarding the importance of the effort to find effective new therapies for cancer patients.

Characterization of de novo folate synthesis in Pneumocystis carinii and Toxoplasma gondii: potential for screening therapeutic agents.

Drug therapy studies imply that Pneumocystis carinii and Toxoplasma gondii possess the enzymes necessary for de novo folate synthesis. To verify this, incorporation of [3H]paraaminobenzoic acid [( 3H]PABA) into reduced folates by P. carinii and T. gondii was investigated. Both organisms synthesized tritiated reduced folates. In P. carinii, 10-formyltetrahydrofolate and tetrahydrofolate, and in T. gondii, 5-formyltetrahydrofolate were the major synthesized folates. P. carinii remained metabolically active in vitro for only a few days. Because current systems for screening antipneumocystis agents are cumbersome, the utility of this assay system for screening therapeutic agents was investigated. Sulfonamides and pentamidine efficiently inhibited de novo folate synthesis in P. carinii. Inhibitors of dihydrofolate reductase such as trimethoprim and trimetrexate were poor inhibitors for P. carinii but efficient inhibitors for T. gondii. This study demonstrates the first unambiguous evidence of metabolic activity in P. carinii, and provides a potential assay for efficiently screening antipneumocystis drugs in vitro.

4-Ipomeanol: a novel investigational new drug for lung cancer.

4-Ipomeanol (IPO) is the first agent to undergo preclinical development at the National Cancer Institute (NCI) based principally on a specific biochemical-biological rationale for clinical investigation as an antineoplastic agent targeted against lung cancer. This disease-specific development of IPO was initially stimulated by observations that the compound was activated by metabolism, preferentially within the mammalian lung, specifically within bronchiolar Clara cells, and that its predominant toxicity was to the lung in most species. IPO is inactive or only minimally active against most conventional antitumor test systems. However, some human lung cancer cell lines, as well as a variety of fresh human lung tumor biopsy specimens, have been shown to be capable of mediating the in situ biotransformation of IPO to a potentially cytotoxic intermediate. In this report, the biochemistry, metabolism, preclinical pharmacology, and toxicology of IPO are reviewed and the clinical development plans for this unique and challenging new agent are presented.

High dose intravenous methotrexate with leucovorin rescue in rheumatoid arthritis.

Five patients with severe, treatment refractory rheumatoid arthritis were treated with high dose intravenous methotrexate (500 mg/m2) followed by leucovorin (50 mg/m2). Four courses of chemotherapy were given over a 2-month interval. At the end of the final course, there was a 50% or greater improvement in joint swelling and pain indices and morning stiffness in all patients. Clinical responses persisted for 6-14 weeks posttherapy. High dose methotrexate-leucovorin was associated with a significant reduction in DR antigen expression on peripheral Leu 2, Leu 3 and Leu 4 lymphocytes.

Potential roles for preclinical pharmacology in phase I clinical trials.

Concepts elucidated from preclinical pharmacology studies have made a substantial impact on the clinical use of anticancer drugs. However, the majority of animal pharmacology results have not been available until after drugs have entered clinical trials. Since clinical pharmacokinetic measurements are already part of many phase I trials, human data could be directly compared with mouse data if mouse pharmacology studies were completed before clinical trials were initiated. Once the starting dose in a phase I clinical trial has been evaluated, subsequent doses are escalated until the maximum tolerated dose is reached. The rate of escalation is empirically defined by a modified Fibonacci series. This universal escalation scheme is applied to all drugs, with no modifications based upon pharmacology or other factors. If the starting dose is far removed from the maximum tolerated dose, a large number of dose escalations are required. Consequently, most patients receive subtherapeutic doses, and the amount of resources allocated to each drug increases. We are exploring potential strategies for controlling the rate of dose escalation based upon pharmacokinetic determinations in mouse and man. Retrospective analyses indicate that 20%-50% savings in the total number of dose escalations are possible.

Presence of 2,4-diamino-N10-methylpteroic acid after high-dose methotrexate.

Assay of plasma methotrexate has been established as important to its safe use. We have investigated the specificity of 2 assay procedures for methotrexate: the competitive dihydrofolate reductase binding assay (CRBA) and the radioimmunoassay (RIA). The RIA of plasma methotrexate resulted in consistently higher values than the CRBA, with greater differences at later measurement times. A compound that strongly cross-reacts in the RIA, but not the CRBA, has been identified in plasma and urine of patients on high-dose methotrexate therapy, and appears to be the carboxypeptidase cleavage product (2,4-diamino-N10-methylpteroic acid) on the basis of chromatographic and ultraviolet spectral properties. Although this compound is present as a minor contaminant in commercial methotrexate preparations, quantitative assessment of urinary excretion suggests that in man a major portion of the compound is derived from methotrexate metabolism.

Treatment of osteogenic sarcoma. I. Effect of adjuvant high-dose methotrexate after amputation.

Thirty-nine patients with extremity osteogenic sarcoma and no discernible metastases were treated with amputation and postoperative adjuvant high-dose methotrexate with leucovorin rescue. One half of the patients were also randomized to receive bacillus Calmette-Guérin by a multiple-puncture technique. Results have been analyzed with a minimum followup of 10 months and a median followup of 27 months. Actuarial analysis estimates that 38% of current protocol patients remain continuously free of disease for 24 months compared to only 17.4% of historical control patients (P = 0.029; one-sided generalized Kruskal-Wallis test). Bacillus Calmette-Guérin administered by a multiple-puncture technique had no effect on disease-free interval. Minor differences between current protocol and historical control patients with regard to race, age, histologic type, and site and size of primary tumors do not affect the difference in disease-free interval between these two patient groups. However, current patients had somewhat lower grade lesions and consideration of the patients with grade III and IV lesions only, lessens the difference between current and historical control patients (P = 0.11; one-sided generalized Kruskal-Wallis test). High-dose methotrexate was administered with virtually no morbidity and no deaths. The small differences observed in this study between protocol patients treated with surgery plus high-dose methotrexate and historical control patients treated with surgery alone point to the need for a prospective randomized study to establish the role of high-dose methotrexate in the adjuvant treatment of patients with osteogenic sarcoma.

Use of plasma pharmacokinetics to predict and prevent methotrexate toxicity.

To correlate the pharmacokinetics and toxicity of methotrexate, we measured the drug's clearance from plasma after 395 high-dose, six-hour infusions given to 78 patients. After 375 infusions, 48 hour methotrexate levels fell within 2 standard deviations of the mean for nontoxic infusions, and myelosuppression did not occur. Methotrexate concentrations exceeded the range for nontoxic patients (mean +/- 2 standard deviations) after 20 infusions. Serious myelosuppression occurred after six of these 20 infusions, including five of 12 infusions associated with 48-hour drug concentrations above 9 X 10(-7) M. In seven patients with 48-hour concentrations above 9 X 10(-7) M, the absence of toxicity could be attributed to subsequent rapid clearance of the drug; four of these patients also received large doses of supplemental leucovorin (50 to 100 mg per square meter every six hours). Determination of methotrexate concentration in plasma thus identified patients at high risk of toxicity, a group that may benefit from supplemental leucovorin rescue.

Preliminary Results of trials of chemotherapy in advanced ovarian carcinoma.

A search for improved forms of systemic chemotherapy in advanced ovarian carcinoma has resulted in two prospective trials at the Medicine Branch National Cancer Institute. The first trial compared high-dose, split-course intravenous cyclophosphamide with conventional treatment with an oral alkylating agent, melphalan [also called L-phenylalanine mustard (PAM)]. While both regimens were essentially equal in therapeutic efficacy, the former was considerably more toxic and the latter was therefore preferred. The second trial employed a 4-drug combination (5-fluorouracil, methotrexate, cyclophosphamide, and hexamethylmelamine); the results indicated a higher overall response rate (85%) and a higher complete remission rate (31%) with the combination therapy than with the PAM therapy, although the study is short and the observations are preliminary.