Our aim was to improve techniques for drug development by facilitating the identification of small molecules that bind with high affinity to acceptor molecules (for example, cell-surface receptors, enzymes, antibodies) and so to mimic or block their interaction with the natural ligand. Previously such small molecules have been characterized individually on a serial basis. The systematic synthesis and screening of peptide libraries of defined structure represents a new approach. For relatively small libraries, predetermined sequence variations on solid-phase supports have been used, and large libraries have been produced using a bacteriophage vector into which random oligodeoxynucleotide sequences have been introduced, but these techniques have severe limitations. Here we investigate an alternative approach to synthesis and screening of peptide libraries. Our simple methodology greatly enhances the production and rapid evaluation of random libraries of millions of peptides so that acceptor-binding ligands of high affinity can be rapidly identified and sequenced, on the basis of a 'one-bead, one-peptide' approach.

The presenting clinical features of 71 patients with multiple myeloma were correlated with myeloma cell mass (myeloma cells X 10(12)/m2 of body surface area) determined from measurements of monoclonal immunoglobulin (M-component) synthesis and metabolism. Bivariate correlation and multivariate regression analyses showed that myeloma cell mass could be accurately predicted from A) extent of bone lesions, B) hemoglobin level, C) serum calcium level, and D) M-component levels in serum and urine. Analyses of response to chemotherapy and survival indicated significant correlation with measured myeloma cell burden. The results were synthesized to produce a very reliable and useful clinical staging system with three tumor cell mass levels (Table 7). For clinical research purposes, multivariate regression equations were developed to predict optimally the exact myeloma cell mass. Thus, initial staging can be quantitatively related to followup using tumor cell mass changes calculated from changes in M-component production. Use of the clinical staging system sould provide better initial assessment and followup of individual patients, and should lead to improved study design and analysis in large clinical trials of therapy for multiple myeloma.

Nephrectomy followed by interferon therapy results in longer survival among patients with metastatic renal-cell cancer than does interferon therapy alone.

A simple method has been developed to support human tumor stem cell colony growth in soft agar. The technique appears suitable for culture of a variety of neoplasms of differing histopathology. Tumor stem cell colonies arising from different types of cancer have differing growth characteristics and colony morphology. This bioassay should be suitable for clinical studies of effects of anticancer drugs or irradiation on human tumor stem cells.

The HDT and SDT regimens used in S9321 yielded comparable response rates and PFS and OS durations. IFN maintenance therapy did not benefit patients who achieved > or = 75% tumor reduction on either arm.

With a direct in vitro tumor-colony assay developed to measure sensitity of human-tumor stem cells to anticancer drugs, we performed 32 retrospective or prospective clinical studies in nine patients with myeloma and nine with ovarian cancer treated with standard agents that were tested in vitro. The results were clearly correlated (P is less than 0.00001). Unique patterns of sensitivity and resistance to the six drugs tested were observed for individual patients. In eight cases of myeloma and three of obarian carcinoma in vitro sensitivity corresponded with in vivo sensitivity whereas in one case of myeloma it did not. In vitro resistance correlated with clinical resistance in all five comparisons in myeloma and all 15 in ovarian cancer. We conclude that this assay shows sufficient promise to warrant larger-scale testing to determine its efficacy for selection of new agents and individualized cancer chemotherapy regimens.

No abstract

The B-cell neoplasms, multiple myeloma and non-Hodgkin's lymphoma, frequently become drug resistant, despite initial responses to chemotherapeutic drugs. Tumor cells from eight patients with clinically drug-refractory disease were evaluated by immuno-histochemical staining for monoclonal immunoglobulin (Ig) expression, nuclear proliferation antigen, P-glycoprotein (P-gly) expression, and other cellular antigens. P-gly was detected on tumor cells from six of eight patients with drug-resistant disease. Of the six patients with P-gly-positive tumors, five patients had advanced multiple myeloma and one had a drug-refractory non-Hodgkin's lymphoma. Cellular RNA analysis confirmed the over-expression of P-gly. In an effort to overcome drug resistance, a pilot study evaluated possible verapamil enhancement of chemotherapy in these eight patients. All patients had developed progressive disease while receiving a regimen containing vincristine and doxorubicin, and seven of eight patients had previously received continuous infusion vincristine and doxorubicin plus oral dexamethasone (VAD). At the time of progressive disease, continuous infusion verapamil was added to the VAD regimen. Three of the eight patients who were refractory to vincristine and doxorubicin alone responded when verapamil was added to VAD. The three patients who responded had P-gly-positive tumors. Verapamil increased the intracellular accumulation of doxorubicin and vincristine in vitro for both a P-gly-positive myeloma cell line and tumor cells from two patients with end-stage myeloma which over-expressed P-gly. The dose-limiting side effect associated with the addition of verapamil to chemotherapy was temporary impairment of cardiac function, manifest as hypotension and cardiac arrhythmia. We conclude that P-gly expression occurs in drug-refractory B-cell neoplasms and may contribute to the development of clinical drug resistance. However, other factors, such as the proliferative activity of the tumor, may also play a role in determining response to chemotherapy. The administration of verapamil along with VAD chemotherapy may partially circumvent drug resistance in patients whose tumors over-express P-gly.