Library

Notes: The overexpression and aberrant function of members of the erbB family of receptors, particularly erbB1 (also known as epidermal growth factor receptor), and its ligands in many human cancers have provided a rationale for targeting this signaling network with novel approaches. erbB1 is a selective target for inhibiting cancers because its activation often confers a proliferative advantage. Activation of the erbB1 tyrosine kinase provides signals that drive dysregulated proliferation, invasion, metastasis, angiogenesis, and cell survival, and its inhibition has potential in both the treatment and prevention of these malignancies. Based on the structure and function of erbB1, two therapeutic strategies have been developed. The first uses human monoclonal antibodies (MAbs) generated against the receptor's ligand-binding extracellular domain. These MAbs block binding of receptor-activating ligands, and, in some cases, can induce receptor endocytosis and downregulation. The second uses small molecules that compete with adenosine triphosphate (ATP) for binding to the receptor's kinase pocket, thereby blocking receptor activation and the transduction of postreceptor signals. Early clinical studies suggest that both approaches are well tolerated and can induce clinical activity in many common malignancies.

Notes: Abstract: Studies combining paclitaxel and doxorubicin in the treatment of metastatic breast cancer have shown dose-limiting toxicities and raised questions relating to the risk of cardiac toxicities. This pilot trial evaluates an alternating approach to assess safety and feasibility of paclitaxel alternating with doxorubicin as chemotherapy for recurrent breast cancer.Twelve patients with measurable or evaluable breast cancer who had received no more than one prior chemotherapy (either as adjuvant therapy or therapy for metastatic disease) and no prior anthracycline- or taxane-containing chemotherapy were included. Paclitaxel was administered at 200 mg/2 as a continuous 24-hour intravenous infusion alternating with doxorubicin at 75 mg/m2 intravenously, administered every 21 days for a maximum of 10 cycles of therapy.Objective responses were observed in seven of 12 patients (58%) (three complete responses and four partial responses). Objective responses were seen in lymph node, visceral, soft tissue, and bony sites of metastases. The median duration of response was 9.6 months (range 1.4–20.6). A total number of 102 cycles of therapy were administered with 8 of 12 patients tolerating all 10 cycles (median of 10 cycles per patient, range 2–10). Adverse effects included mild myalgias, arthralgias, and peripheral neuropathies. Cardiac toxicities included asymptomatic sinus tachycardia, sinus bradycardia, and nonspecific T-wave abnormality. One patient experienced left ventricular failure. There were no serious hypersensitivity reactions. Paclitaxel cycles resulted in lower granulocyte nadirs than doxorubicin cycles. There were no significant differences in thrombocytopenia between the two agents.The feasibility of administering paclitaxel and doxorubicin in alternating cycles was demonstrated. This was a well-tolerated regimen with results supportive of safety in administration in an alternating regimen.

Notes: Abstract Purpose: This study was performed to evaluate the activity of the multitargeted antifolate (MTA or LY231514) against a broad range of human tumors taken directly from patients. Materials and methods: Human tumor colony-forming units were treated with MTA at concentrations of 0.1, 1.0, and 10 μg/ml in 1-h exposure studies. The responses of a limited number of specimens were also evaluated concurrently in 1-h exposures to cisplatin, fluorouracil, irinotecan, and/or paclitaxel. Results: Of 358 specimens plated in the 1-h exposure studies, 148 (41%) were evaluable. Overall, responses were observed in 3% of specimens (4/144) at 0.1 μg/ml, 11% (17/148) at 1.0 μg/ml, and 23% (33/141) at 10 μg/ml. In this range of concentrations achievable clinically, there was a significant concentration-response relationship. At 10 μg/ml in the 1-h exposure studies, the response rate in colorectal cancer specimens was 32% (9/28), and the response rate in non-small-cell lung cancer was 25% (6/24). Responses were also observed in several chemoresistant tumors, including renal cell carcinoma, hepatocellular carcinoma, mesothelioma, and pancreatic carcinoma. The activity of MTA was not completely cross-resistant with that of cisplatin, fluorouracil, irinotecan, and paclitaxel. Conclusions: MTA demonstrated in vitro activity against a spectrum of tumors, including several tumors generally considered chemoresistant.

Notes: Abstract Histamine-2 receptor antagonists (H2RAs) are principal components of the premedication regimen used to prevent major hypersensitivity reactions in patients receiving paclitaxel. Several different H2RAs, including cimetidine, ranitidine and famotidine, have been used in clinical trials of paclitaxel, as well as by clinicians in different geographic regions and hospitals primarily because of differences in the availability of the various H2RAs. However, H2RAs have highly variable cytochrome P450-modulating capabilities, and the P450 system appears to play a major role in paclitaxel metabolism and disposition. Therefore, the use of different H2RAs may result in different pharmacologic, toxicologic and antitumor profiles due to differential effects on paclitaxel metabolism. This study evaluated whether cimetidine and famotidine, which possess disparate P450-modulating capabilities, differentially affect paclitaxel clearance rates and the agent's principal toxicity, neutropenia. Women with advanced, platinum-refractory ovarian carcinoma received two courses of treatment with 135 mg/m2 paclitaxel over 24 h while participating in the National Cancer Institute's Treatment Referral Center Protocol. A crossover design was employed in which consecutive patients received either 300 mg cimetidine i.v. or 20 mg famotidine i.v. before their first course of paclitaxel and the alternate H2RA before their second course. In order to evaluate the differential effects of cimetidine and famotidine on pertinent pharmacologic and toxicologic parameters in the same individual, paclitaxel concentrations at steady-state (Css), paclitaxel clearance rates, and absolute neutrophil counts (ANCs) were obtained during both courses. Paclitaxel Css values were not significantly different in individual patients when either cimetidine or famotidine preceded paclitaxel (p=0.16). Mean paclitaxel clearance rates were 271 and 243 ml/min per m2 following cimetidine and famotidine, respectively. These clearance rates were not significantly different in paired analysis (p=0.30). The likelihood of subsequently requiring granulocyte-colony stimulating factor (G-CSF) for severe neutropenia during course 1 did not differ significantly between the two H2RAs (p=0.9). Among patients who did not require G-CSF, mean percentage decreases in ANC were 87.7% and 84.2% after paclitaxel cycles preceded by cimetidine and famotidine, respectively. These measures of neutropenia did not differ significantly in paired analysis (p=0.13). These results show that the H2RAs cimetidine and famotidine do not differentially affect the pharmacologic and toxicity profiles of paclitaxel when used in the premedication regimen to prevent major hypersensitivity reactions, and may be interchanged.

Notes: Abstract Aging influences the disposition and effects of several classes of drugs. Although drug clearance rate is correlated with toxicity for many anticancer drugs, few data have been published concerning the relationship of aging and clearance of chemotherapy. This study was performed to identify any relationship between age and clearance rate for anticancer drugs in phase I trials at the Johns Hopkins Oncology Center. In a retrospective study, we examined the clinical and pharmacokinetic data for 344 adults (aged 21–77 years) who received 9 phase I drugs with linear clearance in 13 clinical trials. We sought correlations between age and clearance for each drug and for the whole group. Data available for 9 of the 13 trials were used to compare age (〈65 or 〉65 years) versus dose delivered [〈 the maximum tolerated dose (MTD) vs ≥ the MTD] or toxicity (〈 grade 3 vs ≥ grade 3). Of 344 patients, 81 (23.5%) were 〉65 years old, 34 (9.9%) were ≥70 years old, and 5 (1.5%) were ≥75 years old. There was no significant correlation between drug clearance and age for individual drugs or the group as a whole. There was no significant difference between patients of the older and younger age groups with regard to dose or toxicity. Although only a small number of patients aged ≥75 years were treated, our results suggest that the elderly do not experience greater toxicity even when treated at doses comparable with those given younger patients and should not be excluded from phase I trials on the basis of age. As the population of the United States ages, more elderly patients will be candidates for chemotherapy. A more thorough examination of the relationships between age, clearance rate, and toxicity can be accomplished as active drugs enter phase II/III studies.

Notes: Abstract. Aging influences the disposition and effects of several classes of drugs. Although drug clearance rate is correlated with toxicity for many anticancer drugs, few data have been published concerning the relationship of aging and clearance of chemotherapy. This study was performed to identify any relationship between age and clearance rate for anticancer drugs in phase I trials at the Johns Hopkins Oncology Center. In a retrospective study, we examined the clinical and pharmacokinetic data for 344 adults (aged 21–77 years) who received 9 phase I drugs with linear clearance in 13 clinical trials. We sought correlations between age and clearance for each drug and for the whole group. Data available for 9 of the 13 trials were used to compare age (〈65 or 〉65 years) versus dose delivered [〈 the maximum tolerated dose (MTD) vs ≥ the MTD] or toxicity (〈 grade 3 vs ≥ grade 3). Of 344 patients, 81 (23.5%) were 〉65 years old, 34 (9.9%) were ≥70 years old, and 5 (1.5%) were ≥75 years old. There was no significant correlation between drug clearance and age for individual drugs or the group as a whole. There was no significant difference between patients of the older and younger age groups with regard to dose or toxicity. Although only a small number of patients aged ≥75 years were treated, our results suggest that the elderly do not experience greater toxicity even when treated at doses comparable with those given younger patients and should not be excluded from phase I trials on the basis of age. As the population of the United States ages, more elderly patients will be candidates for chemotherapy. A more thorough examination of the relationships between age, clearance rate, and toxicity can be accomplished as active drugs enter phase II/III studies.

Notes: Abstract Paclitaxel is an important agent in the treatment of many common malignancies. Although the symptomatic peripheral neuropathy caused by this drug is its principal nonhematologic toxicity, little is known about the distribution of paclitaxel within the peripheral or central nervous system following systemic administration. In order to study paclitaxel's distribution in neural and extraneural tissues, adult Sprague-Dawley rats were sacrificed 2 h after a tail vein injection of [3H]-paclitaxel (0.03 mg/kg, 250 μCi/rat). Samples of lung, heart, liver, spleen, kidney, skeletal muscle, brain, spinal cord, dorsal root ganglion, and peripheral nerve were then removed and snap-frozen. These tissues were sectioned at 10 μm in a cryostat and exposed to autoradiography film for 2 weeks. The distribution and concentrations of [3H]-paclitaxel in plasma, urine and cerebrospinal fluid were also determined using liquid scintillation spectrometry. [3H]-Paclitaxel concentrations (and organ/plasma concentration ratios) in plasma, urine and cerebrospinal fluid were 2.6 nM (1), 38 nM (15) and 0.7 nM (0.3), respectively. A relatively homogeneous distribution of [3H]-paclitaxel was observed in liver [412 nM (151)], spleen [351 nM (133)], heart [319 nM (117)], lung [268 nM (93)] and muscle [69 nM (26)]. Higher concentrations of [3H]-paclitaxel were noted in the portal triads [869 nM (361)], glomeruli [797 nM (304)], and renal medulla [961 nM (363)], which may reflect biliary excretion and glomerular filtration. A high concentration of [3H]-paclitaxel was also noted in the choroid plexus [432 nM (167)], but [3H]-paclitaxel was not detected in the brain parenchyma, spinal cord, dorsal root ganglion, peripheral nerve, or the testicles. The pathogenesis of paclitaxelinduced neurotoxicity remains obscure given its limited distribution in the nervous system. In addition, these results suggest that systemically administered paclitaxel is not likely to be effective for the treatment of malignancies in the testes or the nervous system.

Notes: Abstract  Paclitaxel is an important agent in the treatment of many common malignancies. Although the symptomatic peripheral neuropathy caused by this drug is its principal nonhematologic toxicity, little is known about the distribution of paclitaxel within the peripheral or central nervous system following systemic administration. In order to study paclitaxel’s distribution in neural and extraneural tissues, adult Sprague-Dawley rats were sacrificed 2 h after a tail vein injection of [3H]-paclitaxel (0.03 mg/kg, 250 μCi/rat). Samples of lung, heart, liver, spleen, kidney, skeletal muscle, brain, spinal cord, dorsal root ganglion, and peripheral nerve were then removed and snap-frozen. These tissues were sectioned at 10 μm in a cryostat and exposed to autoradiography film for 2 weeks. The distribution and concentrations of [3H]-paclitaxel in plasma, urine and cerebrospinal fluid were also determined using liquid scintillation spectrometry. [3H]-Paclitaxel concentrations (and organ/plasma concentration ratios) in plasma, urine and cerebrospinal fluid were 2.6 nM (1), 38 nM (15) and 0.7 nM (0.3), respectively. A relatively homogeneous distribution of [3H]-paclitaxel was observed in liver [412 nM (151)], spleen [351 nM (133)], heart [319 nM (117)], lung [268 nM (93)] and muscle [69 nM (26)]. Higher concentrations of [3H]-paclitaxel were noted in the portal triads [869 nM (361)], glomeruli [797 nM (304)], and renal medulla [961 nM (363)], which may reflect biliary excretion and glomerular filtration. A high concentration of [3H]-paclitaxel was also noted in the choroid plexus [432 nM (167)], but [3H]-paclitaxel was not detected in the brain parenchyma, spinal cord, dorsal root ganglion, peripheral nerve, or the testicles. The pathogenesis of paclitaxel-induced neurotoxicity remains obscure given its limited distribution in the nervous system. In addition, these results suggest that systemically administered paclitaxel is not likely to be effective for the treatment of malignancies in the testes or the nervous system.

Notes: Abstract The camptothecin analogues topotecan and irinotecan (CPT-11) are active anticancer drugs. This article reviews the accumulated results of clinical and laboratory studies performed with these agents at The Johns Hopkins Oncology Center. In a phase I clinical and pharmacology trial of topotecan given as a 30-min infusion daily for 5 days every 3 weeks, profound neutropenia precluded dose escalation above 1.5–2.0 mg/m2 per day, the maximum tolerated dose (MTD). The daily ×5 schedule has been developed further with dose escalation using granulocytecolony-stimulating factor support in patients who have kidney or liver dysfunction and given in combination with cisplatin. In addition, a phase I trial of topotecan given as a 5-day continuous intravenous infusion to patients with refractory leukemia has had promising antileukemic responses. A separate series of in vitro studies indicates that a modest degree of resistance to the cytotoxicity of topotecan can be mediated by P-glycoprotein. A phase I and pharmacology study of irinotecan given as a 90-min infusion every 3 weeks has defined an MTD of 240 mg/m2, with dose escalation being limited by several toxicities. These included an acute treatment-related syndrome of flushing, warmth, nausea, vomiting, and diarrhea; a subacute combination of nausea, diarrhea, anorexia, and weight loss; and/or neutropenia. Antitumor activity has been observed with topotecan and irinotecan in patients with a variety of solid tumors and refractory leukemia in our studies, which supports the widespread enthusiasm for this group of compounds.