Predicting the safety of medicines in pregnancy: A workshop report

The framework for developmental toxicity testing has remained largely unchanged for over 50 years and although it remains invaluable in assessing potential risks in pregnancy, knowledge gaps exist, and some outcomes do not necessarily correlate with clinical experience. Advances in omics, in silico approaches and alternative assays are providing opportunities to enhance our understanding of embryo-fetal development and the prediction of potential risks associated with the use of medicines in pregnancy. A workshop organised by the Medicines and Healthcare products Regulatory Agency (MHRA), "Predicting the Safety of Medicines in Pregnancy - a New Era?", was attended by delegates representing regulatory authorities, academia, industry, patients, funding bodies and software developers to consider how to improve the quality of and access to nonclinical developmental toxicity data and how to use this data to better predict the safety of medicines in human pregnancy. The workshop delegates concluded that based on comparative data to date alternative methodologies are currently no more predictive than conventional methods and not qualified for use in regulatory submissions. To advance the development and qualification of alternative methodologies, there is a requirement for better coordinated multidisciplinary cross-sector interactions coupled with data sharing. Furthermore, a better understanding of human developmental biology and the incorporation of this knowledge into the development of alternative methodologies is essential to enhance the prediction of adverse outcomes for human development. The output of the workshop was a series of recommendations aimed at supporting multidisciplinary efforts to develop and validate these alternative methodologies.

Gender medicine and oncology: report and consensus of an ESMO workshop

BACKGROUND

The importance of sex and gender as modulators of disease biology and treatment outcomes is well known in other disciplines of medicine, such as cardiology, but remains an undervalued issue in oncology. Considering the increasing evidence for their relevance, European Society for Medical Oncology decided to address this topic and organized a multidisciplinary workshop in Lausanne, Switzerland, on 30 November and 1 December 2018.

DESIGN

Twenty invited faculty members and 40 selected physicians/scientists participated. Relevant content was presented by faculty members on the basis of a literature review conducted by each speaker. Following a moderated consensus session, the final consensus statements are reported here.

RESULTS

Clinically relevant sex differences include tumour biology, immune system activity, body composition and drug disposition and effects. The main differences between male and female cells are sex chromosomes and the level of sexual hormones they are exposed to. They influence both local and systemic determinants of carcinogenesis. Their effect on carcinogenesis in non-reproductive organs is largely unknown. Recent evidence also suggests differences in tumour biology and molecular markers. Regarding body composition, the difference in metabolically active, fat-free body mass is one of the most prominent: in a man and a woman of equal weight and height, it accounts for 80% of the man's and 65% of the woman's body mass, and is not taken into account in body-surface area based dosing of chemotherapy.

CONCLUSION

Sex differences in cancer biology and treatment deserve more attention and systematic investigation. Interventional clinical trials evaluating sex-specific dosing regimens are necessary to improve the balance between efficacy and toxicity for drugs with significant pharmacokinetic differences. Especially in diseases or disease subgroups with significant differences in epidemiology or outcomes, men and women with non-sex-related cancers should be considered as biologically distinct groups of patients, for whom specific treatment approaches merit consideration.

Abstract P6-11-10: Preclinical efficacy of the novel PIM2 kinase inhibitor, JP11646 in triple negative breast cancer models

Background: Triple negative breast cancer (TNBC) patients have poorer prognosis and there remains a lack of novel targeted therapies for their treatment. PIM2 (Proviral Integrations of Moloney virus 2) belongs to a family of three kinases that have been implicated in the survival and progression of hematologic malignancies and solid tumors. PIM2 has been linked to epithelial to mesenchymal transition in TNBC, which can lead to metastasis and chemotherapeutic resistance. We hypothesized that PIM2 may present as a therapeutic target in TNBC.

Materials and Methods: The study involved both in vitro and in vivo studies involving a novel PIM2 inhibitor JP11646 (obtained from Jasco Pharmaceuticals). TNBC cell lines MDA-MB-231 and BT-549 were obtained for our in vitro studies. Cell viability was evaluated using MTT assay. Western Blot assay was used to evaluate relative protein expression. For in vivo studies, female SCID mice were inoculated in the mammary fat pads with 1 × 106 MDA-MB-231 cells. When tumor volumes reached 100 mm3, the mice were treated with JP11646 at the dosage 15mg/kg intraperitoneally for 2 consecutive days weekly for total of 4 weeks as determined from previous experiments. Control animals received vehicle only. The mice were euthanized once tumors reached ∼1,700 mm3.

Results: BT-549 cells treated in vitro with 3 different available PIM kinase inhibitors AZD 1208, LGB321 and JP12641 showed only modest reduction in cell viability. However, treatment of both MDA-MB-231 and BT-549 with JP 11646 demonstrated significant reduction in cell viability with IC50 ranging from 40 to 71.6 nM. Treatment with JP11646 demonstrated a novel mechanism of action resulting in downregulation of PIM2 in both cell lines. Treatment with JP11646, but not other PIM kinase inhibitors, resulted in activation of apoptosis as measured by cleaved PARP (cPARP) levels. Anti-PIM2 siRNA treatment but not treatment with non-specific PIM kinase inhibitor AZD1208 resulted in cPARP induction. Inhibition of proteolysis by bortezomib resulted in preservation of PIM2 and inhibition of apoptosis as demonstrated by decreased cPARP levels after treatment with JP11646. PIM2 over-expressing clone of MDA-MB-231 cells showed enhanced proliferation and migration properties both in vitro and in vivo.Treatment of mice with orthotopically implanted MDA-MB-231 tumors with JP 11646 resulted in significant reduction in the tumor growth (p=0.0019) and increased overall survival (p=0.018) as compared to control mice.

Conclusions: PIM2 upregulation in TNBC cell line resulted in more aggressive phenotype. JP11646, through novel mechanism of action resulting in degradation of PIM2, showed robust activity in TNBC cell lines both in vitro and in vivo. Further correlative studies in tumors harvested from in vivo experiments are ongoing. These results encourage further exploration of use of JP11646 as a targeted agent in treatment of TNBC.

Citation Format: Mehta R, Kothai Guruswamy Sangameswaran D, Bezbatchenko K, Moore J, Gil M, Khoury T, Baldino C, Caserta J, Fetterly, Jr. G, Lee K, Adjei A, Opyrchal M. Preclinical efficacy of the novel PIM2 kinase inhibitor, JP11646 in triple negative breast cancer models [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-10.

Crimean-Congo hemorrhagic fever virus in livestock ticks and animal handler seroprevalence at an abattoir in Ghana

Background

Crimean-Congo Haemorrhagic Fever Virus (CCHFV) is a zoonotic virus transmitted by Ixodid ticks and causes Crimean-Congo hemorrhagic fever (CCHF) disease in humans with up to 50 % mortality rate.

Methods

Freshly slaughtered livestock at the Kumasi abattoir in the Ashanti Region of Ghana were examined for the presence of ticks once a month over a 6-month period from May to November 2011. The ticks were grouped into pools by species, sex, and animal source. CCHFV was detected in the ticks using reverse transcription PCR. Blood samples were collected from enrolled abattoir workers at initiation, and from those who reported fever in a preceding 30-day period during monthly visits 2–5 months after initiation. Six months after initiation, all participants who provided baseline samples were invited to provide blood samples. Serology was performed using enzyme linked immunosorbent assay (ELISA). Demographic and epidemiological data was also obtained from enrolled participants using a structured questionnaire.

Results

Of 428 freshly slaughtered animals comprising 130 sheep, 149 cattle, and 149 goats examined, 144 ticks belonging to the genera Ambylomma, Hyalomma and Boophilus were identified from 57 (13.3 %): 52 (34.9 %), 4 (3.1 %) and 1 (0.7 %) cattle, sheep and goat respectively. Of 97 tick pools tested, 5 pools comprising 1 pool of Hyalomma excavatum and 4 pools of Ambylomma variegatum, collected from cattle, were positive for CCHFV. Of 188 human serum samples collected from 108 abattoir workers, 7 (3.7 %) samples from 6 persons were anti-CCHF IgG positive with one of them also being CCHF IgM positive. The seroprevalence of CCHFV identified in this study was 5.7 %.

Conclusions

This study detected human exposure to CCHF virus in slaughterhouse workers and also identified the CCHF virus in proven vectors (ticks) of Crimean Congo hemorrhagic fever in Ghana. The CCHFV was detected only in ticks collected from cattle, one of the livestock known to play a role in the amplification of the CCHF virus.

2nd ESMO Consensus Conference on Lung Cancer: non-small-cell lung cancer first-line/second and further lines of treatment in advanced disease

To complement the existing treatment guidelines for all tumour types, ESMO organises consensus conferences to focus on specific issues in each type of tumour. The 2nd ESMO Consensus Conference on Lung Cancer was held on 11-12 May 2013 in Lugano. A total of 35 experts met to address several questions on non-small-cell lung cancer (NSCLC) in each of four areas: pathology and molecular biomarkers, first-line/second and further lines of treatment in advanced disease, early-stage disease and locally advanced disease. For each question, recommendations were made including reference to the grade of recommendation and level of evidence. This consensus paper focuses on first line/second and further lines of treatment in advanced disease.

A phase I/II pharmacokinetic and pharmacogenomic study of calcitriol in combination with cisplatin and docetaxel in advanced non-small-cell lung cancer

BACKGROUND

Preclinical studies demonstrated antiproliferative synergy of 1,25-D3 (calcitriol) with cisplatin. The goals of this phase I/II study were to determine the recommended phase II dose (RP2D) of 1,25-D3 with cisplatin and docetaxel and its efficacy in metastatic non-small-cell lung cancer.

METHODS

Patients were ≥18 years, PS 0-1 with normal organ function. In the phase I portion, patients received escalating doses of 1,25-D3 intravenously every 21 days prior to docetaxel 75 mg/m(2) and cisplatin 75 mg/m(2) using standard 3 + 3 design, targeting dose-limiting toxicity (DLT) rate <33 %. Dose levels of 1,25-D3 were 30, 45, 60, and 80 mcg/m(2). A two-stage design was employed for phase II portion. We correlated CYP24A1 tagSNPs with clinical outcome and 1,25-D3 pharmacokinetics (PK).

RESULTS

34 patients were enrolled. At 80 mcg/m(2), 2/4 patients had DLTs of grade 4 neutropenia. Hypercalcemia was not observed. The RP2D of 1,25-D3 was 60 mcg/m(2). Among 20 evaluable phase II patients, there were 2 confirmed, 4 unconfirmed partial responses (PR), and 9 stable disease (SD). Median time to progression was 5.8 months (95 % CI 3.4, 6.5), and median overall survival 8.7 months (95 % CI 7.6, 39.4). CYP24A1 SNP rs3787554 (C > T) correlated with disease progression (P = 0.03) and CYP24A1 SNP rs2762939 (C > G) trended toward PR/SD (P = 0.08). There was no association between 1,25-D3 PK and CYP24A1 SNPs.

CONCLUSIONS

The RP2D of 1,25-D3 with docetaxel and cisplatin was 60 mcg/m(2) every 21 days. Pre-specified endpoint of 50 % confirmed RR was not met in the phase II study. Functional SNPs in CYP24A1 may inform future studies individualizing 1,25-D3.

Survival of patients (pts) treated with high-dose radiotherapy (RT) and concurrent chemotherapy for unresectable non-small cell lung cancer (NSCLC)

7544

Background: NCCTG N0028 was a trial that determined the MTD of RT that could be given with carboplatin & paclitaxel was 74 Gy/34 fractions. This secondary analysis was performed to determine the survival of pts treated on this trial. Methods: Eligible pts had medically or surgically unresectable NSCLC, PS=0–1, weight loss <10% in the prior 3 months(mo), no prior therapy, adequate laboratory & pulmonary functions. Included were 25 pts with clinical stages I (4pts), II (1 pt), IIIa (12 pts), & IIIb (8 pts). Treatment included: weekly I.V. paclitaxel (50mg/m2) & carboplatin (AUC=2) during RT. The RT included 2 Gy daily to an initial dose of 70 Gy. The total dose was increased in 4 Gy increments until the MTD was determined. RT was delivered with 3-D treatment planning but no elective nodal RT. Three pts received 70 Gy, 18 pts received 74 Gy, & 4 pts received 78Gy. Results: Pts were followed until death or from 10–67 mo (median: 28mo) in those alive at last evaluation. The median survival (MS) of the entire cohort was 42mo. The 5 stages I-II pts had a MS of 53 mo & the 20 stage III pts had MS of 42mo. Conclusions: Standard dose RT is unable to sterilize disease in the majority of pts with unresectable NSCLC. While the addition of chemotherapy has significantly improved survival of these pts, the MS is generally 15–24 mo. These preliminary results suggest higher than standard doses of RT may improve disease control & prolong survival. A phase III trial comparing standard-dose RT(60Gy) to high-dose RT (74Gy) is open and should more definitively address the issue of RT dose with concurrent chemotherapy for unresectable NSCLC. Future technological improvements in imaging & targeting will provide methods to safely administer even greater RT doses which will likely further improve disease control.

No significant financial relationships to disclose.

Circulating tumor cells expressing the insulin growth factor-1 receptor (IGF-1R): Method of detection, incidence and potential applications

3507

Purpose: To detect IGF-1R on circulating tumor cells (CTCs) as a biomarker in the clinical development of a monoclonal human antibody, CP-751,871, targeting IGF-1R. Experimental Design: An automated sample preparation and analysis system for enumerating CTCs (Celltracks) was adapted for detecting IGF-1R positive CTCs with a diagnostic antibody targeting a different IGF-1R epitope to CP-751,871. This assay was utilized in three phase I trials of CP-751,871 as a single agent or with chemotherapy and was validated using cell lines and blood samples from healthy volunteers and patients with metastatic carcinoma. Results: There was no interference between the analytical and therapeutic antibodies. CP-751,871 was well tolerated as a single agent, and in combination with docetaxel or carboplatin and paclitaxel, at doses ranging from 0.05 mg/kg to 20 mg/kg. Eighty patients were enrolled on phase 1 studies of CP-751,871, with 47 (59%) patients having CTCs detected during the study. Prior to treatment 26 patients (33%) had CTCs, with 23 having detectable IGF-1R positive CTCs. CP-751,871 alone, and CP-751,871 with cytotoxic chemotherapy, decreased CTCs and IGF-1R positive CTCs; these increased towards the end of the 21-day cycle in some patients, falling again with retreatment. CTCs were commonest in advanced hormone refractory prostate cancer (11/20). Detectable IGF-1R expression on CTCs before treatment with CP-751,871 and docetaxel was associated with a higher frequency of PSA decline by more than 50% (6/10 vs 2/8 patients). A relationship was observed between sustained falls in CTCs counts and PSA declines by more than 50%. Conclusions: IGF-1R expression is detectable by immunofluorescence on CTCs. These data support the further evaluation of CTCs in pharmacodynamic studies and patient selection, particularly in advanced prostate cancer.

No significant financial relationships to disclose.

A phase I study of lapatinib and topotecan in patients with solid tumors

3598

Background: Drug resistance to topotecan can be the result of BCRP/ABCG2 expression. BCRP is a member of the ABC transporter family that pumps anticancer drugs out of the cell. Lapatinib is a potent and selective dual inhibitor of epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 (Her2/Neu). 4-aminoquinazoline tyrosine kinase inhibitors have been shown to enhance the cytotoxicity of topotecan through inhibition of BCRP-mediated drug efflux in cancer cells. Methods: Thirty-seven patients with advanced stage cancers were enrolled at escalating dose levels of lapatinib and topotecan in cohorts IA, IB and IIB (MTD). Treatment schedule included lapatinib (750 - 1500 mg/d) daily for 21 (cohort IA) or 28 days (cohort IB) and topotecan (2.4 - 4.0 mg/ m2), days 1, 8 and 15; cycles were repeated every 28 days. Three patients were treated at each dose level, 18 on cohort IA, 9 on cohort IB and 10 at MTD (cohort IIB). Assessments of toxicity were performed with each cycle and clinical response was determined per RECIST criteria every other cycle. Results: The MTD for cohorts IA and IB was reached at a dose of 1250 mg of lapatinib and 3.2 mg/m2 of IV topotecan on days 1, 8 and 15. No DLT were seen during the dose escalation stage of cohorts IA and IB. Ten patients were enrolled at the MTD. There were no grade 4+ events. Thirteen grade 3+ events, considered to be related to treatment, were seen in 6 patients. The most common grade 3+ toxicities included dehydration (2) diarrhea (2), nausea (3), vomiting (2), neutropenia (1), thrombocytopenia (1), and fatigue (1). No abnormalities in left ventricular ejection fraction were noted. Stable disease was seen in 46% of the 37 patients. Conclusions: The combination of lapatinib and topotecan is a well-tolerated regimen. The MTD for the combination is lapatinib 1,250 mg orally once daily for 21 or 28 days and topotecan 3.2 mg/m2 on days 1, 8 and 15. Pharmacokinetic analysis for drug interaction will be available for presentation at the meeting. Supported in part by GSK and Mayo Clinic

No significant financial relationships to disclose.

Glutathione pathway genes predict quality of life (QOL) in lung cancer patients: A NCCTG-97–24–51 based study

18037

Background: Platinum compounds are major chemotherapeutic agents in lung cancer and are metabolized by the glutathione pathway enzymes. We reported that genotypes of glutathione-related enzymes, especially GCLC, may be host factors in predicting survival of patients with stage IIIB/IV non-small cell lung cancer who were stable or responding from prior platinum-based chemotherapy (Yang et al., ASCO 2006). NCCTG investigators previously correlated allelic variants in 5-FU metabolizing genes with QOL in colorectal cancer patients (Sloan et al., ASCO 2004). We sought to evaluate the role of glutathione pathway genotypes on QOL. Methods: DNA samples were analyzed using 6 polymorphic DNA markers in the glutathione metabolic pathway. The contrasting genotypes in the analysis were GSTM1 and GSTT1 (null vs. present), GSTP1-I105V (AA vs. GA/GG), GSTP1-A114V (CC vs. CT/TT), GPX1 (CC vs. TT/TC), and GCLC (homozygous repeat 77 vs. heterozygous 7*). Forty-six patients completed the FACT-L and the UNISCALE QOL questionnaires at baseline and week-8, and we have results for all 6 genotypes. A clinically significant decline (CSD) in QOL was defined as a 10% decrease from baseline to week-8. A multivariate logistic regression model was used to evaluate the association of all 6 genotypes with a CSD in QOL. Results: Patients carrying the GPX1-CC genotype had a CSD in the UNISCALE (Odds Ratio (OR): 10.0; p=0.02), total FACT-L score (OR: 7.9; p=0.03), the FACT-L physical well being construct (OR: 13.7; p=0.02), and the FACT-L functional well being construct (OR: 5.3; p=0.05). Other constructs, i.e., emotional, social and family, and additional concerns were not significantly associated with the genotypes. Conclusions: Genotypes of glutathione-related enzymes, especially GPX1 may be inherited factors in predicting patients’ QOL after platinum-based chemotherapy. Further investigation to define and measure the direct or indirect effects of these genes on QOL is critical, particularly, via drug responses, toxicities, and disease recurrence. (This work was partly supported by NIH grants CA77118, CA80127, and CA84354.)

No significant financial relationships to disclose.

Cryptosporidium oocysts in Ghanaian AIDS patients with diarrhoea

BACKGROUND

Although Cryptosporidiumspp. infections in acquired immunodeficiency syndrome patients (AIDS) with chronic diarrhoea have been reported in several African countries, there is no information regarding cryptosporidial diarrhoea in Ghanaian AIDS patients.

OBJECTIVE

To investigate the occurrence of C. parvum and other gastrointestinal parasitic agents in Ghanaian AIDS patients with chronic diarrhoea.

DESIGN

Prospective study of HIV/AIDS patients with diarrhoea over a nine month period.

SETTING

Korle-Bu Teaching Hospital and Korle-Bu Polyclinic Accra, Ghana.

RESULTS

Analysis of stool specimens from clinically diagnosed HIV/AIDS (n = 21; mean CD4 count was 288 cells per microliter, 95% confidence interval of 237 to 340 cells per microliter) and HIV-seronegative (n = 27) patients revealed C. parvum in six (28.6%) of HIV/AIDS and 10 (37.0%) of the HIV-seronegative patients, respectively. Three other HIV/AIDS cases had other infections involving Strongyloides stercoralis 4.8% (1/21) and Salmonella spp. 9.5% (2/21). There was no concomitant association between C. parvum and any other parasites found. Also, no enterobacteria was found in the HIV-seronegative patients.

CONCLUSION

This study demonstrates the prevalence of Cryptosporidium sp. in both HIV/ AIDS and HIV-seronegative individuals in Ghana. However, there was no statistical association between cryptosporidiosis and HIV/AIDS (p > 0.05).

A−61C and C−101G Hp gene promoter polymorphisms are, respectively, associated with ahaptoglobinaemia and hypohaptoglobinaemia in Ghana

We have investigated the genetic basis for the Hp0 phenotype amongst 123 randomly selected Ghanaians. A total of 17 individuals were determined to be Hp0 phenotype, based on the classical method for Hp phenotyping of Hb-supplemented plasma. Out of the 17 Hp0 individuals, nine subjects were further classified as ahaptoglobinaemic and eight as hypohaptoglobinaemic by Western blots and double immunodiffusion. We identified three previously known base substitutions (A-55G, A-61C and T-104A) and three new ones (C-101G, T-191G and C-242T) within the 5' flanking region of the Hp gene. The A-61C base substitution significantly decreased transcriptional activity and was associated strongly with Hp2 allele and ahaptoglobinaemia. The C-101G substitution was similar in transcriptional activity to the wild-type and was associated with Hp1S allele and hypohaptoglobinaemia. The Hpdel allele seen in Asian populations was absent. We conclude that the Hp0 phenotype in Ghana has a genetic basis that differs significantly from that seen in Asia.

The effect of soybean protein on bone loss in a rat model of postmenopausal osteoporosis

This study was designed to investigate the modulatory effect of dietary soybean protein on the skeleton of an ovariectomized rat model with postmenopausal osteoporosis. Thirty-two female Sprague-Dawley rats were weight matched and divided into the following four experimental groups: Soy group, ovariectomized and fed soy protein diet; Estrogen group, ovariectomized, fed casein diet and injected with estrogen; Casein group, ovariectomized and fed casein diet; and Sham group, sham-operated and fed casein diet. The diets and estrogen were started two weeks after surgery, and continued for four weeks. Rats in the Sham, Soy and Estrogen groups had significantly higher (p < 0.05) femur and tibia ash content than those in the Casein group. Accordingly, the calcium content of the tibia and femur were also significantly higher (p < 0.05) in the Soy, Estrogen and Sham groups as compared to the Casein group. Serum total and bone-type alkaline phosphatase levels were both significantly lower (p < 0.05) in the Estrogen and Sham groups in relation to the Soy and Casein groups. This study demonstrated that a 22% soybean protein diet could be just as effective as daily estrogen administration in suppressing bone loss due to ovariectomy. However, unlike estrogen, soy protein diet did not have any uterotrophic effect and did not decrease the markers of bone turnover measured, suggesting a possible difference in the mechanism of action.

Throat microflora in breastfed and formula-fed infants

Most bacterial infections are caused by organisms that are already colonizing the host, and these infections commonly originate at site of the gastrointestinal and respiratory tracts. However, little attention has been focused on the indigenous microflora of the respiratory tract in the infant. We studied the throat microflora of healthy breastfed and formula-fed infants. The incidence of pathogenic bacterial isolation from breastfed infants (1 out of 23) was lower relative to infants fed formula (5 out 14). The dominant bacteria in the throat flora isolated in both breastfed and formula-fed infants were alpha-haemolytic Streptococcus and gamma Streptococcus. These results suggest that breastmilk may be effcacious in preventing the growth of pathogenic bacteria in the throat.

Phase I and pharmacodynamic study of the topoisomerase I-inhibitor topotecan in patients with refractory acute leukemia

PURPOSE

To determine the feasibility of escalating the hydrophilic topoisomerase I (topo I)-inhibitor topotecan (TPT) above myelosuppressive doses in adults with refractory or relapsed acute leukemias and to assess pharmacodynamic determinants of TPT action.

PATIENTS AND METHODS

Seventeen patients received 33 courses of TPT as a 5-day infusion at doses ranging from 0.70 to 2.7 mg/m2/d. Pharmacologic studies were performed to determine the TPT concentrations at steady-state (Css) and to examine parameters in the patients' leukemic blasts ex vivo that may be related to TPT sensitivity, eg, topo I content, p-glycoprotein (Pgp) expression, and the inhibitory effects of relevant TPT concentrations on the growth of blast colonies in clonogenic assays relative to the range of TPT Css values achieved.

RESULTS

Severe mucositis of the oropharynx and perianal tissues was intolerable at TPT doses greater than 2.1 mg/m2/d, the recommended dose for phase II studies in leukemia. One complete response (CR) in a patient with chronic myelogenous leukemia in blast crisis (CML-B) and one partial response (PR) in a patient with acute myelogenous leukemia (AML) were noted. Significant reductions in circulating blast-cell numbers occurred in all courses, and complete leukemia clearance from the peripheral blood, albeit transient, was noted in 11 courses. TPT Css values ranged from 4.8 to 72.5 nmol/L. Colony-forming assays showed that the TPT LD90 (dose that inhibits the growth of leukemia blast colonies by 90%) values for blasts varied from 6 to 22 nmol/L, a range that overlapped with TPT Css values. In view of these variations in TPT sensitivity, several aspects of topo I-mediated drug action were also studied. In 10 of 11 samples, the multi-drug resistance (Mdr) modulator quinidine altered nuclear daunorubicin (DNR) accumulation and whole-cell TPT accumulation by less than 15%, which suggests that Pgp-mediated effects on drug efflux are insufficient to explain the fourfold range of TPT sensitivities in the colony-forming assays. Immunohistochemistry showed that topo I was expressed in all of the blasts from individual patients without detectable cell-to-cell heterogeneity in each marrow. Western blots indicated that topo I content varied over a 10-fold range. Although the sample size was small, topo I content appeared to be higher in acute lymphoblastic leukemia (ALL), intermediate in AML, and lower in CML-B. Topo I content did not appear to be related to the proliferative status of the blasts.

CONCLUSION

These results indicate that substantial dose escalation of TPT above myelosuppressive doses reached in solid-tumor patients is feasible in patients with refractory leukemia, that biologically relevant TPT Css values are achievable, and that further developmental trials are warranted.

Effect of formulation adjuvants on gastrointestinal absorption of leuprolide acetate

Leuprolide acetate, [D-Leu6-desGly10]LH-RH ethylamide, a highly potent superagonist of luteinizing hormone-releasing hormone (LH-RH), was administered by intraduodenal (ID) injection to male castrate rats in a saline solution. Absorption was low, approximately 0.01% and 0.08% by oral (PO) and ID administration respectively, compared with intravenous (i.v.) controls. An aqueous formulation and a water in oil emulsion of a lipophilic salt, a decane sulfonic acid derivative of [D-Leu6-desGly10]LH-RH ethylamide gave ID bioavailabilities of approximately 0.2% and 1%, respectively. Evaluation of formulation effects on the oral absorption of leuprolide showed that lipophilicity, surfactant and vehicle properties significantly affected ID absorption of leuprolide. Absolute bioavailability of the drug in typical emulsion systems ranged from approximately 3 to 10% and represent an improvement of about 100 fold in gastrointestinal bioavailability of this peptide. The implications of these findings relative to the effect of formula adjuvants on oral absorption of leuprolide and other peptides following ID administration are discussed.

Bioavailability of leuprolide acetate following nasal and inhalation delivery to rats and healthy humans

Systemic delivery of leuprolide acetate, a luteinizing hormone releasing hormone (LHRH) agonist, was compared after inhalation (i.h.) and intranasal (i.n.) administration. The i.n. bioavailability in rats was significantly increased by alpha-cyclodextrin (CD), EDTA, and solution volume. Intraanimal variability was 30-60%, and absorption ranged from 8 to 46% compared to i.v. controls. Studies in healthy human males were conducted with leuprolide acetate i.n. by spray, or inhalation aerosol (i.h.), and subcutaneous (s.c.) and intravenous (i.v.) injection. The s.c. injection was 94% bioavailable compared with i.v. The i.n. bioavailability averaged 2.4%, with significant subject-to-subject variability. Plasma peak concentrations (Cmax) with 1- and 3-mg dosages ranged between 0.24-1.6 and 0.10-11.0 ng/ml, respectively. The low human bioavailability may be due to physical loss of drug down the oral cavity and differences between human and rat nasal mucosa. Inhalation delivery gave a slightly lower intersubject variability. Mean Cmax with a 1-mg dose of solution aerosol was 0.97 ng/ml, compared with 4.4 and 11.4 ng/ml for suspension aerosols given at 1- and 2-mg bolus dosages, respectively. The mean bioavailability of the suspension aerosols (28% relative to s.c. administration) was fourfold greater than that of the solution aerosol (6.6%), suggesting that LHRH analogues may be delivered systemically via the lung as aerosol dispersions.

Pulmonary delivery of peptide drugs: effect of particle size on bioavailability of leuprolide acetate in healthy male volunteers

Leuprolide acetate, a nonapeptide with potent luteinizing hormone releasing hormone (LHRH) agonist activity, has low oral bioavailability. Unique aerosols of leuprolide acetate were developed and particle size distribution studies were carried out. A light scattering method (Malvern Model 2600c) was compared to the impaction method (Andersen Sampler) for measuring size distribution. Results showed the Malvern method to be comparable to the impaction method with the Malvern being faster and easier to use. Absolute bioavailability of leuprolide acetate in healthy human male volunteers ranged from 4% to 18% and agreed well with particle size data. Bioavailability corrected for respirable fraction ranged from 35% to 55%, indicating that the pulmonary route may have high potential for systemic delivery of this peptide.

Membrane solubility parameter and in situ release of theophylline

The solubility of theophylline in polyethylene glycol 400-water binary mixtures was analyzed in terms of solute-solvent interaction using the solubility parameter principle of Hildebrand. Preliminary in situ (rat gut permeation) studies with the solvent mixtures having varying polarity as expressed by the solubility parameter showed that (a) the more alike the solubility parameter of theophylline (delta 2 = 14, as obtained from solubility studies) and the solubility parameter of the solvent mixture, the greater was the attraction of solvent for the drug (b) sufficient similarity must exist between the solubility parameter of theophylline and that of the intestinal mucosa to promote bioabsorption, and (c) from the above, it follows that there exists a competition between solvent and rat gut membrane for the drug. The solubility parameter of the solvent vehicle must be such that it does not impede absorption of the molecules into the intestinal mucosa.

Extended Hildebrand solubility approach: testosterone and testosterone propionate in binary solvents

Solubilities of testosterone and testosterone propionate in binary solvents composed of the inert solvent, cyclohexane, combined with the active solvents, chloroform, octanol, ethyl oleate, and isopropyl myristate, were investigated with the extended Hildebrand solubility approach. Using multiple linear regression, it was possible to obtain fits of the experimental curves for testosterone and testosterone propionate in the various binary solvents and to express these in the form of regression equations. Certain parameters, mainly K and log alpha 2, were employed to define the regions of self-association, nonspecific solvation, specific solvation, and strong solvation or complexation.

Extended Hildebrand solubility approach and the log linear solubility equation

The log linear solubility equation, log S = log Sw + sigma f, was studied in relationship to the extended Hildebrand solubility approach. It is shown that the log linear form may be derived beginning with the extended Hildebrand approach. The log linear expression gives a good linear fit for semipolar drugs in a number of water-cosolvent mixtures. It is particularly successful when the solubility parameter, delta 1, of the cosolvent is 3 or more solubility parameter units larger than the solubility parameter, delta 2, of the drug. When the cosolvent tends to solvate the drug strongly, the log linear function may even hold where the solubility parameters of the drug and cosolvent are similar. It appears, however, not to be applicable to nonpolar cosolvent systems. An interfacial model for the solubility of drugs in polar mixed solvents is based on sigma, a parameter that also figures prominently in the log linear solubility equation. When used to describe mixed solvent systems, the interfacial model applies in the region of the solubility profile (solubility versus solvent composition) where the log linear relationships hold. The extended Hildebrand solubility approach is applicable over a wide range of cosolvent composition in mixed systems from nonpolar organic solvents to water.