A single-arm, multicenter, phase II trial of osimertinib in patients with epidermal growth factor receptor exon 18 G719X, exon 20 S768I, or exon 21 L861Q mutations

BACKGROUND

For patients with stage IV non-small-cell lung cancer with epidermal growth factor receptor (EGFR) exon 19 deletions and exon 21 L858R mutations, osimertinib is the standard of care. Investigating the activity and safety of osimertinib in patients with EGFR exon 18 G719X, exon 20 S768I, or exon 21 L861Q mutations is of clinical interest.

PATIENTS AND METHODS

Patients with stage IV non-small-cell lung cancer with confirmed EGFR exon 18 G719X, exon 20 S768I, or exon 21 L861Q mutations were eligible. Patients were required to have measurable disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, and adequate organ function. Patients were required to be EGFR tyrosine kinase inhibitor-naive. The primary objective was objective response rate, and secondary objectives were progression-free survival, safety, and overall survival. The study used a two-stage design with a plan to enroll 17 patients in the first stage, and the study was terminated after the first stage due to slow accrual.

RESULTS

Between May 2018 and March 2020, 17 patients were enrolled and received study therapy. The median age of patients was 70 years (interquartile range 62-76), the majority were female (n = 11), had a performance status of 1 (n = 10), and five patients had brain metastases at baseline. The objective response rate was 47% [95% confidence interval (CI) 23% to 72%], and the radiographic responses observed were partial response (n = 8), stable disease (n = 8), and progressive disease (n = 1). The median progression-free survival was 10.5 months (95% CI 5.0-15.2 months), and the median OS was 13.8 months (95% CI 7.3-29.2 months). The median duration on treatment was 6.1 months (range 3.6-11.9 months), and the most common adverse events (regardless of attribution) were diarrhea, fatigue, anorexia, weight loss, and dyspnea.

CONCLUSIONS

This trial suggests osimertinib has activity in patients with these uncommon EGFR mutations.

Phase II randomized trial of carboplatin, paclitaxel, bevacizumab with or without cixutumumab (IMC-A12) in patients with advanced non-squamous, non-small-cell lung cancer: a trial of the ECOG-ACRIN Cancer Research Group (E3508)

Background

Cixutumumab is a fully human IgG1 monoclonal antibody to the insulin-like growth factor type I receptor that can potentially reverse resistance and enhance the efficacy of chemotherapy.

Methods

Bevacizumab-eligible patients with stage IV or recurrent non-squamous, non-small-cell lung cancer and good performance status were randomized to receive standard doses of paclitaxel, carboplatin, and bevacizumab to a maximum of six cycles followed by bevacizumab maintenance (CPB) until progression (arm A) or CPB plus cixutumumab 6 mg/kg i.v. weekly (arm B).

Results

Of 175 patients randomized, 153 were eligible and treated (78 in arm A; 75 in arm B). The median progression-free survival was 5.8 months (95% CI 5.4-7.1) in arm A versus 7 months (95% CI 5.7-7.6) in arm B (P = 0.33); hazard ratio 0.92 (95% CI 0.65-1.31). Objective response was 46.2% versus 58.7% in arm A versus arm B (P = 0.15). The median overall survival was 16.2 months in arm A versus 16.1 months in arm B (P = 0.95). Grade 3/4 neutropenia and febrile neutropenia, thrombocytopenia, fatigue, and hyperglycemia were increased with cixutumumab.

Conclusions

The addition of cixutumumab to CPB increased toxicity without improving efficacy and is not recommended for further development in non-small-cell lung cancer. Both treatment groups had longer OS than historical controls which may be attributed to several factors, and emphasizes the value of a comparator arm in phase II trials.

ClinicalTrials.gov Identifier

NCT00955305.

Geomorphic and geologic controls of geohazards induced by Nepal's 2015 Gorkha earthquake

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes' induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.

Docetaxel and imatinib every 21 days for castration resistant prostate cancer: A phase II trial

e16086

Background: Docetaxel (D) IV every 21 days, is the only cytotoxic agent that prolongs survival in men with castrate resistant prostate cancer (CRPC). Imatinib (I), a tyrosine kinase inhibitor, modulates PDGFR-ß in tumor vasculature. Based on phase I data from our institution, we hypothesized that D plus I would prolong time to progression (TTP) in patients (pts) with CRPC. Methods: Subjects with CRPC received D 60 mg/m2 IV every 21 days plus I 400 mg PO daily. After 10 pts, the study treatment was modified due to toxicity so that pts received I 400 mg on 10 of 21 days/cycle. The primary endpoint was TTP. Secondary endpoints were rate of PSA response and overall survival (OS). The sample size of 43 pts was designed to provide 90% power to detect an increase in TTP from 5 to 8 months. Results: 43 pts enrolled from 8/05 to 9/08. Age at enrollment ranged from 54–86 years (median 69 years). 14 pts received <1 cycle of D plus I and were unevaluable: 10 had significant toxicity, 4 due to non-treatment related reasons. Primary toxicities were hematologic: 21% G4 neutropenia, 5% G4 anemia, and no G4 thrombocytopenia. Fatigue, nausea, diarrhea, and electrolyte abnormalities were common, but <2 cases each of G3-G4 toxicity occurred. 1 case of G5 non-neutropenic sepsis occurred. 29 pts received >2 cycles of chemotherapy (mean 4.6). 12 pts had PR (41.4%), 9 had SD (31.0%), and 8 had no response (27.6%) by PSA. No objective responses were seen by CT imaging among 10 pts with measurable disease. 3 pts remain on trial. For evaluable pts, overall median TTP was 6.4 months (95% CL: 4.8, 8.4 months) compared with TTP of 5 months seen in previous trials. 23 (79%) pts had PSA progression, 3 pts died before progression, and 3 pts remain on trial. For all evaluable pts who had PR or SD by PSA (N = 21), median TTP was 7.1 months (95% CL: 5.5, 9.1 months). Median OS was 23.1 months (95% CL: 11.61 months, NR), compared with 18.9 months for GC Conclusions: Docetaxel on day 1 plus imatinib 10 days of each 21-day cycle resulted in meaningful improvement in TTP in the subset of pts who showed a response. Toxicity precludes its use in the general population, although its role in select pts with good performance status needs to be explored.

[Table: see text]

Phase II study of gefitinib and docetaxel as salvage therapy in patients (pts) with advanced pancreatic adenocarcinoma (APC)

4120

Background: There is no standard-of-care second-line chemotherapy for APC. The combination of docetaxel and gefitinib, an inhibitor of epidermal growth factor receptor (EGFR) shows enhanced preclinical activity compared to docetaxel alone. Docetaxel alone has activity in APC, and this phase II trial is designed to evaluate the combination. The primary endpoint is survival with an accrual goal of 45 patients to detect an improvement to 5.25 months (mo) in median survival time by one-sided log-rank test at level α = 0.05. Methods: Patients with APC and one prior chemotherapy regimen are eligible for study; EGFR over-expression is not required. Gefitinib is administered at the dose of 250 mg/day orally without interruption. The initial dose of docetaxel was 75 mg/m2 every three weeks (one cycle), but was reduced to 60 mg/m2 due to a high incidence of febrile neutropenia. Results: 31 pts, all with prior gemcitabine therapy, have been enrolled on study to date, with 26 evaluable for toxicity. Patient characteristics: 62% male; 92 % with ECOG performance status 0/1, 8% ECOG of 2; median age 64 years (range 47–82 years). The best response is stable disease (5 pts), median cycles administered 2 (range 1–12). Thus far the median survival time is 4.4 mo, with median time to progression of 2.5 mo. Grade (G) 3/4 febrile neutropenia occurred in 8 out of 18 pts treated at the 75 mg/m2 dose of docetaxel; none has been seen with the 60 mg/m2 dose. Other G 3/4 adverse events include: diarrhea (3.8%), rash (7.7%), constitutional symptoms (11.5%), and nausea (11.5%). Conclusion: The combination of gefitinib and docetaxel at 60 mg/m2 is tolerable, with interim results showing a median survival time of 4.4 mo at this point. If the protocol’s goal of median survival time of 5.25 mo is met upon study completion, the combination may be worthy of further investigation.

No significant financial relationships to disclose.

Lung cancer

Is any one combination therapy for metastatic non-small cell lung cancer (NSCLC) superior to other regimens for metastatic NSCLC? The answer is "probably no." More than 4,000 patients with advanced NSCLC participated in randomized trials presented at the 37th Annual Meeting of the American Society of Clinical Oncology. TAX326 was the only study in which the investigational arm (cisplatin/docetaxel) showed a statistically significant difference in survival compared with the reference standard (cisplatin/vinorelbine). We did learn, however, that what we administer may make some difference: cisplatin might be superior to carboplatin, and patients treated with nonplatinum chemotherapy regimens have a trend toward poorer survival than those who receive platinum doublets. Although there is still no clear best regimen for advanced NSCLC, we may now know how much chemotherapy to give: a randomized study presented found that four cycles produces as much survival benefit as treating until progression. The most significant abstracts presented at this year's lung cancer session involved the use of novel agents with unique mechanisms of action. The median survival in the large, randomized trials of chemotherapy in advanced NSCLC remains a bleak 9 months. ISIS 3521, an antisense oligonucleotide that targets protein kinase C, was found to produce a near doubling of survival when combined with carboplatin and paclitaxel. OSI-774, an epidermal growth factor receptor tyrosine kinase inhibitor, was shown to have impressive single agent activity in the second-line treatment of lung cancer. The future of lung cancer therapy will involve combining these novel agents with active chemotherapy regimens in an effort to improve outcome. While we appear to have reached a plateau in what we can accomplish with various combinations of cytotoxic chemotherapy in metastatic NSCLC, in locally-advanced disease new chemotherapy combinations can achieve remarkable results when combined with radiation therapy. The Southwest Oncology Group presented unprecedented phase II data on the use of cisplatin and etoposide with concurrent radiation therapy followed by consolidation docetaxel in patients with stage IIIB NSCLC.

Tick-raccoon associations and the potential for Lyme disease spirochete transmission in the coastal plain of North Carolina

Raccoons (Procyon lotor) were live-trapped and examined for ticks from July 1990 to July 1993 in the coastal plain of North Carolina on Marine Corps Base, Camp Lejeune, North Carolina (USA). Five species of ixodid ticks were found on 351 (78%) of 449 raccoons. Amblyomma americanum was the most abundant tick found on raccoons. Dermacentor variabilis, Ixodes texanus, and Ixodes scapularis were frequently collected, while Ixodes cookei were rarely collected from raccoons. Tick burdens were not affected by the age, sex, or trap location of captured raccoons. Ticks parasitizing raccoons had varying seasonal patterns of abundance. Amblyomma americanum were generally collected from raccoons year around, but infestation intensities were greatest in summer from June to September. Dermacentor variabilis adults were most abundant in mid-summer while peak numbers of larvae were collected in the fall. Infestation intensities of Ixodes texanus larvae were greatest in fall and winter months while nymphs were most abundant in winter and spring. No males were collected from raccoons, but females were most frequently collected in the spring and declined in abundance in the summer with no specimens collected in the fall or winter. Numbers of 1. scapularis adults appeared to reach peak numbers in the fall while larvae and nymphs were most abundant on raccoons in winter. Spirochetes, Borrelia burgdorferi, were identified in a small percentage (0.2%) of host-seeking A. americanum nymphs and adults, and I. scapularis adults by immunofluorescent antibody assays. Similarly, a small percentage (1.9%) of host-associated A. americanum, D. variabilis, I. texanus and I. cookei contained B. burgdorferi. Borrelia burgdorferi spirochetes were cultured from the blood of 23 (26%) of 87 raccoons.

Relative utilization of reptiles and rodents as hosts by immature Ixodes scapularis (Acari: Ixodidae) in the coastal plain of North Carolina, USA

The interaction of immature black-legged ticks, Ixodes scapularis, with reptiles and rodents was investigated in various woodland habitats in the coastal plain of North Carolina. Reptiles were sampled from April 1 to September 30, 1991. No ticks were found on 95 specimens representing 16 species of snakes. Ticks were found on 54 (36.7%) of 147 lizards. I. scapularis was the only tick recovered from lizards. Some lizards were collected in drift fence traps each month of the study except August. Capture rates averaged one lizard per 16 trap-days. Larvae and nymphs of I. scapularis were removed from the southeastern five-lined skink (Eumeces inexpectatus), the ground skink (Scincella lateralis), the broad-headed skink (E. laticeps) and the eastern glass lizard (Ophisaurus ventralis), but ticks were not found on three other lizard species. Tick infestation rates and loads for parasitized species are presented. Ticks were almost exclusively attached at the base or in the axils of forelimbs of skinks and in the lateral grooves of eastern glass lizards. Rodents were live-trapped at sites where lizards were sampled and at other sites from 1 July, 1990 to 30 January, 1992. Capture rates averaged one rodent per 47 trap-nights. Ticks were found on 23 (17.8%) of 129 animals inspected. Five species of rodents were examined but only four species were found to be tick-infested. In contrast to lizards, few I. scapularis were collected. Rodents, principally the white-footed mouse (Peromyscus leucopus) and cotton mouse (P. gossypinus) were most frequently infested with immature American dog ticks, Dermacentor variabilis, during winter and early spring months. Burdens of D. variabilis on these rodents averaged 0.3 ticks per rodent. Effects of the diversion of ticks from feeding on Peromyscus mice on the transmission of the Lyme disease spirochete are discussed.

Large-scale production of murine monoclonal antibodies using hollow fiber bioreactors

We have produced large quantities of murine monoclonal antibodies for in vivo human clinical trials using hollow fiber bioreactors (HFBRs). Thirty-three different hybridoma cell lines have been evaluated in various HFBR systems. Monoclonal antibody (Ab) productivity is highly dependent on the intrinsic secretory rate of each cell line. Other factors that affect Ab production include capillary membrane molecular weight cutoff, and HFBR design. Studies comparing HFBRs to static and suspension culture systems revealed similar Ab productivity. An advantage of the HFBR is that the Ab is concentrated in the extracapillary space, simplifying downstream processing.

Defective T-cell colony formation and IL-2 receptor expression at all stages of HIV infection

The T-cell colony assay is a highly sensitive measure of immunological dysfunction. The present study evaluated this in vitro response in asymptomatic HIV-infected homosexuals, those with chronic adenopathy as their only clinical manifestation and patients with either ARC or AIDS. The mean colony count in antibody-positive asymptomatic individuals was significantly reduced when compared to either heterosexual controls or antibody-negative homosexuals. Furthermore, there were no differences in the responses of these antibody-positive individuals and those with chronic lymphadenopathy as their only clinical manifestation. By contrast, patients with AIDS or ARC showed a profound defect; this suggests that the colony assay can detect a functional gradient across the spectrum of HIV infections. Colony growth was correlated with the absolute number of T-helper cells and the ability of PHA-stimulated lymphocytes to express IL-2 receptors; no correlation was found with the number of suppressor/cytotoxic cells or in vitro production of IL-2. Recent HIV seroconverters had normal colony counts but impaired ability to express IL-2 receptors. These data suggest a sequential loss of T-cell function as a result of HIV infection; the earliest manifestations are impaired expression of IL-2 receptors and reduced proliferative responses, as measured in the colony assay.

High-dose megestrol acetate therapy of ovarian carcinoma: a phase II study by the Northern California Oncology Group

The activity of high-dose megestrol acetate was studied in 47 patients with epithelial ovarian cancers after failure of initial chemotherapy. The dose of megestrol acetate was 800 mg/d orally (PO) for 4 weeks and then 400 mg/d until tumor progression. Patients generally had far-advanced disease. Prior therapy included cisplatin, doxorubicin, and cyclophosphamide (PAC) or other cisplatin-containing regimens in 37, other combinations in eight, and single agents in only two patients. Seventeen patients (36%) developed intestinal obstructions within the first 2 months on study. Tumor histology was serous in 37, endometrioid in six, and clear-cell in two. Two thirds of the tumors were histologic grade 3, and the others were grade 2. Complete remission was obtained in one patient, with time to progression of 4 months. There were three partial remissions, with times to progression of 4, 5, and 18 months. The overall response rate (complete and partial) was 8%. Three additional patients had minor remissions (3, 5, and 8 months), and five had stable disease, for 3, 4, 5, 6, and 9 months. There was no correlation of response with grade, histologic type, or site of disease, but responding patients had a longer survival from diagnosis to protocol entry and from protocol failure to death than did nonresponding patients. The major side effect of megestrol acetate was increased appetite, which caused one patient to withdraw from the study, and resulted in a 10- to 20-kg weight gain in five patients. Plasma levels of megestrol acetate averaged 600 ng/mL in the first month of therapy and decreased to approximately 400 ng/mL at 8 and 12 weeks, after the drug dosage had been reduced. Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were markedly lower during megestrol therapy compared with pretreatment values. Megestrol acetate at 1 microgram/mL in vitro inhibited soft agar colony formation from one of 17 specimens of ovarian carcinomas. We conclude that megestrol acetate in high doses has modest, but definite, palliative effects in some patients with advanced ovarian carcinoma in whom chemotherapy has failed. A controlled trial of megestrol plus combination chemotherapy as first-line treatment of advanced ovarian carcinoma should be considered.

Defective in vitro T cell colony formation in the acquired immunodeficiency syndrome

Depressed T cell immunity is a universal characteristic of the acquired immunodeficiency syndrome (AIDS). In the present study, 25 patients with AIDS and opportunistic infections, 22 individuals with AIDS-related complex (ARC, or chronic lymphadenopathy syndrome), and 20 healthy homosexuals were evaluated by means of the T cell colony assay. Forty-seven healthy heterosexual controls showed an average of 3964 +/- 319 colonies/7.5 X 10(5) cells, with a range of 880 to 9340. The mean in the 20 healthy homosexuals (3173 +/- 483) did not differ significantly from the controls; in this group, only three patients had values less than 1000 colonies/plate. By contrast, all AIDS patients and 14 ARC patients had colony counts less than 1000. The mean value for the AIDS patients was only 24 +/- 15 (p less than 0.0005 compared with either controls or healthy homosexuals); values in the ARC group were intermediate (1180 +/- 360). The addition of interleukin 2 to the plates promoted correction of the proliferative abnormality in ARC patients. This interleukin increased colony scores in the AIDS group, but the mean value was still significantly less than controls. Comparison indicated that the colony assay is a more sensitive indicator for detecting proliferative abnormalities than responses to PHA, Con A, or pokeweed mitogen in suspension cultures.

Defective in vitro T cell colony formation in the acquired immunodeficiency syndrome

Depressed T cell immunity is a universal characteristic of the acquired immunodeficiency syndrome (AIDS). In the present study, 25 patients with AIDS and opportunistic infections, 22 individuals with AIDS-related complex (ARC, or chronic lymphadenopathy syndrome), and 20 healthy homosexuals were evaluated by means of the T cell colony assay. Forty-seven healthy heterosexual controls showed an average of 3964 +/- 319 colonies/7.5 X 10(5) cells, with a range of 880 to 9340. The mean in the 20 healthy homosexuals (3173 +/- 483) did not differ significantly from the controls; in this group, only three patients had values less than 1000 colonies/plate. By contrast, all AIDS patients and 14 ARC patients had colony counts less than 1000. The mean value for the AIDS patients was only 24 +/- 15 (p less than 0.0005 compared with either controls or healthy homosexuals); values in the ARC group were intermediate (1180 +/- 360). The addition of interleukin 2 to the plates promoted correction of the proliferative abnormality in ARC patients. This interleukin increased colony scores in the AIDS group, but the mean value was still significantly less than controls. Comparison indicated that the colony assay is a more sensitive indicator for detecting proliferative abnormalities than responses to PHA, Con A, or pokeweed mitogen in suspension cultures.

Thrombotic thrombocytopenic purpura: clinical course and response to therapy in eight patients

The clinical manifestations, pathologic findings, and responses to therapy were reviewed in eight patients with thrombotic thrombocytopenia purpura (TTP). Only one exhibited all five cardinal manifestations; five showed a triad of anemia, thrombocytopenia, and neurologic abnormalities. Microangiopathic red cell changes on peripheral blood smear and severe thrombocytopenia were present in all. The serum LDH levels were initially elevated in all eight; this enzyme determination was extremely useful for following the course of the disease and its response to therapy. Pathologic evidence of TTP was most consistently found in lymph nodes, spleen, and bone marrow biopsies. All patients were treated with a combination of therapeutic modalities including plasma exchange with replacement by fresh frozen plasma. Using this approach, 7/8 entered a complete remission; however, disappearance of all clinical manifestations was not seen in two patients prior to splenectomy.

T lymphocyte colony assay in hemophiliacs

Unexplained lymphadenopathy, with or without accompanying symptoms, known as the "lymphadenopathy syndrome," has been recognized in groups at risk for acquired immune deficiency syndrome (AIDS), namely, homosexuals and hemophiliacs. To date, however, no test has been defined that discriminates between asymptomatic individuals and those with adenopathy in these high-risk groups. The T colony assay, which measures T lymphocyte growth in soft agar and which allows selective T cell proliferation with minimal cell-cell contact, was evaluated in asymptomatic hemophiliacs. Significantly lower mean colony counts were found in eight hemophiliacs with adenopathy (HA), 763 +/- 348 (+/- SEM), than in 16 healthy hemophiliacs (HH) 3,044 +/- 661 (P less than .005), or than in 24 heterosexual control subjects, 3,964 +/- 395 (P less than .005). The in vitro addition of exogenous interleukin-2 (IL-2) restored normal colony growth in the HA population. These results indicate that the T colony assay can detect abnormal cell-mediated immunity among hemophiliacs and specifically discriminates between asymptomatic hemophiliacs (HH) and those with adenopathy (HA). In addition, IL-2 may be of potential benefit in improving T cell defects in AIDS or the "lymphadenopathy syndrome"; however, this remains to be proven.

Failure of erythromycin in treatment of Legionella micdadei pneumonia

A 59-year-old immunocompromised woman had nosocomial Legionella micdadei infection that failed to respond to two weeks of erythromycin in high intravenous doses and oral rifampin. Treatment with intravenous trimethoprim-sulfamethoxazole and oral rifampin, which previously has not been used in this infection, resulted in cure.

Clinical responses of dogs to experimentally induced Dipetalonema reconditum infection

Six male and 6 female Beagles, 6 to 7 months old, were allotted to 2 groups: group I--inoculated subcutaneously with 30 Dipetalonema reconditum infective larvae/dog, and group II--noninoculated controls. Group comparisons were made in regard to hematologic values, Knott test results, body weights, blood urea nitrogen, total serum protein, serum albumin and alanine aminotransferase and creatine kinase activities. Routine urinalysis data were compared at 1 week before and at 28 weeks after the inoculations. Mean total leukocyte counts were significantly (P less than 0.05) greater in group I dogs than in group II dogs at postinoculation weeks (PIW) 4, 5, and 7 to 12, and mean eosinophil counts were significantly greater in group I dogs at PIW 3 to 11, 13 to 15, 20, and 23 to 24. Microfilariae were detected as early as the 10th week and sporadically thereafter. Only 1 D reconditum adult worm was recovered from all of the inoculated dogs. Five other dogs (group III) with chronic, patient experimentally induced dipetalonemiasis, were evaluated with the same tests at PIW 70 to 89. Eosinophilia (greater than 750 cells/microliter) was present in 4 of 5 dogs; lymphocytosis (greater than 4,800 cells/microliter) was evident in 1 dog. Proteinuria (greater than or equal to 30 mg/dl) was detected in 3 of 4 dogs with chronic dipetalonemiasis.

In vitro degradation of L-phenylalanine mustard (L-PAM)

L-Phenylalanine mustard (L-PAM), a bis-choroethylamine, is an important drug in the treatment of multiple myeloma and ovarian cancer. It undergoes rapid hydrolysis in vitro and in vivo, forming the mono-and dihydroxy degradation products. L-PAM's first-order disappearance rate in a phosphate-buffered solution did not differ statistically according to the presence or absence of activated rat liver microsomal enzymes. Furthermore, L-PAM's disappearance rate in a rat whole liver perfusion system was not greater than its hydrolysis rate in water. In vitro plasma recovery studies showed that up to 85% of the 14C L-PAM drug equivalents could be recovered as the parent compound and the mono- and dihydroxy degradation products. Thus, L-PAM in in vitro degradation was similar qualitatively and quantitatively to its reported in vivo degradation in animals and man. It is concluded that L-PAM does not undergo important, active in vivo metabolism.

Methodologic problems in clonogenic assays of spontaneous human tumors

Colony formation in soft agar was used to investigate growth properties and drug sensitivity in 102 tumor specimens from 91 patients. Sufficient colony growth for sensitivity testing with various drugs was obtained in 36 of 67 specimens (54%) with adequate cell yield and pathologically documented malignancy. Room temperature (20-24 degrees C) is superior to both 4 degrees C and 37 degrees C for 12-36 h storage and transport of malignant effusions. By contrast, fine mincing in sterile saline or balanced salt solution, and refrigerated storage (4 degrees C) appear optimal in experiments with three solid tumors. The use of buffered NH4Cl to lyse red blood cells markedly reduced plating efficiencies, and also reduced the percentage of tumors in which drug sensitivities could be tested from 64% to 38%. Several combinations of potential growth factors and culture media have been tested. Insulin enhanced plating efficiency (PE) in all six adenocarcinomas tested. Drug sensitivity of tumors was not affected by varying plating efficiency up to five-fold in two tumors. In eleven cases tumor cells were exposed to combinations of two or more drugs, and results assessed for evidence of drug interactions. In almost all cases, these two-drug combinations produced additive cell killing than either antagonistic or greater-than-additive effects.U

Concentration profile for the dissolution of drug tablets undergoing simultaneous degradation

An empirical approach to the concentration-time history of a dissolving drug has resulted in a cube-root equation in which the characteristic constant of the equation embodies the important physical variables of the system. This expression has been used to study the dissolution of a drug that degrades simultaneously in the test solution. An alternative representation of the dissolution process is first-order kinetics. These two approaches are compared by fitting the experimental data of the dissolution of digoxin and melphalan tablets in various media, and a new method for the proper analysis of data for the dissolution of tablets that simultaneously degrade in the test solution is presented.

Comparative pharmacokinetics of chlorambucil and melphalan in man

We have studied the pharmacokinetics of orally administered chlorambucil and melphalan in patients with hematologic malignancies and solid tumors. With a standard oral dose of 0.6 mg/kg, chlorambucil showed much more rapid systemic appearance than did melphalan and had a mean peak plasma concentration and area under the plasma disappearance curve which was 3-4 times greater than that observed in patients receiving melphalan. Melphalan had extremely variable systemic availability which was not observed with chlorambucil, and was not related to problems in tablet formulation. Chlorambucil undergoes extensive active metabolism to phenylacetic acid mustard, whereas melphalan undergoes rapid chemical degradation and has little, if any, active metabolism. On a pharmacokinetic basis, chlorambucil's greater in vitro stability, its more rapid and predictable systemic availability after oral dosing, and its extremely low urinary excretion make it a more predictable alkylating agent for clinical use than melphalan, especially for patients with reduced renal function.

Oral melphalan kinetics

The systemic availability of melphalan after oral administration is not well known. Most patients are put on a fixed oral dosage regimen. We have studied the disposition of melphalan in 14 patients after single oral doses. Five were also studied after receiving the same dose intravenously. Oral melphalan had a mean plasma terminal phase half-life (t1/2) of 90 +/- 17 min. The mean area under the plasma concentration:time curve (CXT) was 53 +/- 33 micrograms . min/ml. Urinary excretion of oral melphalan averaged 10.9 +/- 4.9% during the first 24 hr. The CXT ratio (oral:intravenous) for the 5 patients studied after both oral and intravenous melphalal (0.6 mg/kg) ranged between 0.25 and 0.89 and averaged 0.56. After oral dosing in 14 fasting patients, the time at which melphalan first appeared in the plasma varied between 15 min and 6 hr. In a myeloma patient who took oral melphalan, no melphalan was found in plasma or urine up to 24 hr. Some instances of failure of tumor response to oral melphalan may be due to inadequate bioavailability rather than inherent tumor resistance.

Kinetics of intravenous melphalan

We have studied the disposition and elimination of melphalan after intravenous administration in 9 patients with cancer. High-pressure liquid chromatography and 14C-melphalan were used to assay drug concentration in plasma and urine. Composite plasma t1/2alpha was 7.7 +/- 3.3 and t1/2beta was 108 +/- 20.8 min for 8 of the patients. The mean 24-hr urinary excretion of melphalan was 13.0 +/- 5.4% of the administered dose. In 2 patients, 80% to 100% of the measured 14C counts in plasma and urine samples at each study interval, up to 24 hr after drug administration, could be accounted for by the sum of parent compound, monohydroxy and dihydroxy products, and methanol nonextractable radioactivity (i.e., protein-bound activity). These data and evidence of rapid disappearance from plasma at 37 degrees in vitro suggest that spontaneous degradation, and not enzymatic metabolism, is the major determinant of the t1/2 of melphalan in vivo.