Improved tolerability of neratinib in patients with HER2-positive early-stage breast cancer: the CONTROL trial

BACKGROUND

Neratinib is an irreversible pan-HER tyrosine kinase inhibitor approved for extended adjuvant treatment in early-stage HER2-positive breast cancer based on the phase III ExteNET study. In that trial, in which no antidiarrheal prophylaxis was mandated, grade 3 diarrhea was observed in 40% of patients and 17% discontinued due to diarrhea. The international, open-label, sequential-cohort, phase II CONTROL study is investigating several strategies to improve tolerability.

PATIENTS AND METHODS

Patients who completed trastuzumab-based adjuvant therapy received neratinib 240 mg/day for 1 year plus loperamide prophylaxis (days 1-28 or 1-56). Sequential cohorts evaluated additional budesonide or colestipol prophylaxis (days 1-28) and neratinib dose escalation (DE; ongoing). The primary end point was the incidence of grade ≥3 diarrhea.

RESULTS

Final data for loperamide (L; n = 137), budesonide + loperamide (BL; n = 64), colestipol + loperamide (CL; n = 136), and colestipol + as-needed loperamide (CL-PRN; n = 104) cohorts, and interim data for DE (n = 60; completed ≥six cycles or discontinued; median duration 11 months) are available. No grade 4 diarrhea was observed. Grade 3 diarrhea rates were lower than ExteNET in all cohorts and lowest in DE (L 31%, BL 28%, CL 21%, CL-PRN 32%, DE 15%). Median number of grade 3 diarrhea episodes was one; median duration per grade 3 episode was 1.0-2.0 days across cohorts. Most grade 3 diarrhea and diarrhea-related discontinuations occurred in month 1. Diarrhea-related discontinuations were lowest in DE (L 20%, BL 8%, CL 4%, CL-PRN 8%, DE 3%). Decreases in health-related quality of life did not cross the clinically important threshold.

CONCLUSIONS

Neratinib tolerability was improved with preemptive prophylaxis or DE, which reduced the rate, severity, and duration of neratinib-associated grade ≥3 diarrhea compared with ExteNET. Lower diarrhea-related treatment discontinuations in multiple cohorts indicate that proactive management can allow patients to stay on neratinib for the recommended time period. CLINICALTRIALS.GOV: NCT02400476.

Effects of neratinib on health-related quality of life in women with HER2-positive early-stage breast cancer: longitudinal analyses from the randomized phase III ExteNET trial

BACKGROUND

We report longitudinal health-related quality-of-life (HRQoL) data from the international, randomized, double-blind, placebo-controlled phase III ExteNET study, which demonstrated an invasive disease-free survival benefit of extended adjuvant therapy with neratinib over placebo in human epidermal growth factor receptor-2-positive early-stage breast cancer.

PATIENTS AND METHODS

Women (N  = 2840) with early-stage HER2-positive breast cancer who had completed trastuzumab-based adjuvant therapy were randomly assigned to neratinib 240  mg/day or placebo for 12  months. HRQoL was an exploratory end point. Patients completed the Functional Assessment of Cancer Therapy-Breast (FACT-B) and EuroQol 5-Dimensions (EQ-5D) questionnaires at baseline and months 1, 3, 6, 9, and 12. Changes from baseline were compared using analysis of covariance with no imputation for missing values. Sensitivity analyses used alternative methods. Changes in HRQoL scores were regarded as clinically meaningful if they exceeded previously reported important differences (IDs).

RESULTS

Of the 2840 patients (intention-to-treat population), 2407 patients were evaluable for FACT-B (neratinib, N  = 1171; placebo, N  = 1236) and 2427 patients for EQ-5D (neratinib, N  = 1186; placebo, N  = 1241). Questionnaire completion rates exceeded 85%. Neratinib was associated with a decrease in global HRQoL scores at month 1 compared with placebo (adjusted mean differences: FACT-B total, -2.9 points; EQ-5D index, -0.02), after which between-group differences diminished at later time-points. Except for the FACT-B physical well-being (PWB) subscale at month 1; all between-group differences were less than reported IDs. The FACT-B breast cancer-specific subscale showed small improvements with neratinib at months 3-9, but all were less than IDs. Sensitivity analyses exploring missing data did not change the results.

CONCLUSIONS

Extended adjuvant neratinib was associated with a transient, reversible decrease in HRQoL during the first month of treatment, possibly linked to treatment-related diarrhea. With the exception of the PWB subscale at month 1, all neratinib-related HRQoL changes did not reach clinically meaningful thresholds. ClinicalTrials.gov: NCT00878709.

Abstract PD3-06: Neratinib + fulvestrant for HER2-mutant, HR-positive, metastatic breast cancer: Updated results from the phase 2 SUMMIT trial

Background: HER2 mutations define a rare subset of metastatic breast cancer (MBC) with a unique mechanism of oncogenic addiction to HER2 signaling. Neratinib, an irreversible pan-HER tyrosine kinase inhibitor, has demonstrated single-agent clinical activity in HER2-mutant MBC. In HER2-mutant, HR+ MBC, neratinib + fulvestrant (N+F) appears synergistic vs single-agent neratinib, possibly due to more complete inhibition of bi-directional signaling between HER2 and estrogen receptors. Here we describe interim efficacy results of the expanded HER2-mutant, HR+ MBC cohort treated with N+F from SUMMIT (NCT01953926).

Methods: HR+ MBC patients (pts) with HER2 mutations documented by local testing received oral neratinib 240mg qd and intramuscular fulvestrant (labeled dose). Intensive loperamide prophylaxis was mandatory during cycle 1. Efficacy endpoints include objective response rate at week 8 (ORR8); confirmed objective response rate (ORR); clinical benefit rate (CBR); duration of response (DOR); progression-free survival (PFS); response was assessed by RECIST 1.1 and/or PET Response Criteria. Genomic profiling from fresh/archival tumor tissues and/or plasma cfDNA was performed retrospectively by next-generation sequencing (MSK-IMPACT).

Results: As of 18 May 2018, 46 HER2-mutant HR+ MBC pts have been treated with N+F. Most pts were pretreated, with 91% having received prior anti-cancer medication for MBC (range 0–10). ORR was 33% and median DOR in the 15 pts with a confirmed response was 9.2 months (95% CI 3.9–18.5). Twenty-four pts had prior fulvestrant exposure, and 19 had received prior CDK4/6i-based therapy. Clinical activity was observed with ORRs of 17% and 26% in prior fulvestrant-treated and prior CDK4/6i-treated pts, respectively. ORRs by HER2 mutation were: V777L 63% (5/8 pts); S310F/Y 67% (4/6 pts); G778_P780dup 50% (3/6 pts). Diarrhea was the most common adverse event (grade 3, 24%; grade 4, 0%). Median cumulative duration of grade 3 diarrhea was 3 days. There were no treatment discontinuations due to diarrhea.

 Neratinib + fulvestrantOutcomeaAll patients (N=46)Prior fulvestrant (N=24)Prior CDK4/6i-based therapy (N=19)ORR8 – n (%)19 (41.3)8 (33.3)7 (36.8)95% CI27.0–56.815.6–55.316.3–61.6ORR – n (%)15 (32.6)4 (16.7)5 (26.3)95% CI19.5–48.04.7–37.49.1–51.2DOR for each responder, months 5.6b; 9.2; 9.6b; 18.55.6b; 5.7b; 9.3; 9.6b; 12.9bCBR – n (%)27 (58.7)11 (45.8)9 (47.4)95% CI43.2–73.025.6–67.224.4–71.1Median (95% CI) time to event,c monthsPFS3.9 (3.6–5.7)3.7 (3.5–12.8)3.9 (1.9–NA)DOR9.2 (3.9–18.5)NANAaFor pts with both RECIST- and PET-evaluable lesions, the best of either RECIST or PET response was used to determine response; the earliest progression by RECIST or PET was used for progression; bPt has not progressed; cKaplan-Meier analysis; NA, not applicable

Conclusions: N+F demonstrates encouraging clinical activity with durable responses in heavily pretreated pts with HER2-mutant, HR+ MBC. Of note, responses were observed in pts who had received prior fulvestrant or CDK4/6 inhibitors. No new safety signals were identified; the rate of diarrhea was similar to single-agent neratinib and not dose limiting. Updated data after additional follow-up and genomic data will be presented.

Citation Format: Smyth LM, Piha-Paul SA, Saura C, Loi S, Lu J, Shapiro GI, Juric D, Mayer IA, Arteaga C, de la Fuente M, Brufksy AM, Mau-Sørensen M, Arnedos M, Moreno V, Sohn J-H, Schwartzberg L, Gonzàlez-Farré X, Cervantes A, Mann G, Shahin S, Cutler, Jr. RE, Eli LD, Xu F, Bagulho T, Lalani AS, Bryce R, Solit DB, Hyman DM, Meric-Bernstam F, Baselga J. Neratinib + fulvestrant for HER2-mutant, HR-positive, metastatic breast cancer: Updated results from the phase 2 SUMMIT trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-06.

Abstract P1-13-11: Neratinib in the extended adjuvant treatment of patients from Asia with early-stage HER2+ breast cancer after trastuzumab-based therapy: Exploratory analyses from the phase III ExteNET trial

Background: Current breast cancer knowledge is based largely on studies conducted in western populations. Their findings may not be generalizable to Asian women because of ethnic, genetic and lifestyle differences. Neratinib (N) is an irreversible tyrosine kinase inhibitor of HER1, 2 and 4. The international, randomized, placebo (P)-controlled phase III ExteNET trial showed that 1 year (yr) of N after trastuzumab (T)-based adjuvant therapy significantly improved 2-yr invasive disease-free survival (iDFS) in patients (pts) with early-stage HER2+ breast cancer (HR 0.67; 95% CI 0.50–0.91; p=0.009) [Chan et al. Lancet Oncol 2016]. The significant iDFS benefit with N was shown to be durable after 5 yrs' follow-up (HR 0.73; 95% CI 0.57-0.92; p=0.008) [Martin et al. ESMO 2017]. We report efficacy and safety findings from pts enrolled from Asian centers (China, Hong Kong, Japan, Korea, Malaysia, Singapore, and Taiwan) on the ExteNET trial to better characterize the effects of N in Asian women.

Methods: Pts with early-stage HER2+ breast cancer were randomly assigned to oral N 240 mg/day or P for 1 yr after standard primary therapy and T-based adjuvant therapy. Antidiarrheal prophylaxis was not required by protocol. Data concerning disease recurrences were collected prospectively during yr 1-2 post-randomization, and from medical records during yr 3–5 post-randomization. Primary endpoint: iDFS. HR (95% CI) estimated using Cox proportional-hazards models stratified by nodal status, hormone-receptor status and prior T regimen. Data cut-off: 2-yr analysis, July 2014; 5-yr analysis, March 2017. Clinicaltrials.gov:NCT00878709.

Results: Of 2840 randomized pts (N, n=1420; P, n=1420), 341 (12%) were enrolled from Asian centers (N, n=165; P, n=176). Baseline characteristics: median age 53 yr; hormone receptor-positive 48%. Median treatment duration was similar in both groups (N, 351 days; P, 352 days). iDFS events in Asian vs ITT populations are shown in the Table.

 Primary 2-yr analysisa5-yr analysis NPNPAsian population, n165176165176iDFS events, n10151222HR (95% CI)b0.71 (0.31-1.57)0.54 (0.26-1.08)P-value (2-sided)0.4040.085ITT population, n1420142014201420iDFS events, n67106116163HR (95% CI)b0.66 (0.49-0.90)0.73 (0.57-0.92)P-value (2-sided)0.0080.008a. Primary study endpoint; b. Neratinib vs placebo

The incidence of grade 3/4 diarrhea with N was slightly higher in Asian pts (46.1% vs ITT, 39.8%). All other grade 3/4 adverse events with N were rare among Asian pts (elevated ALT, mucosal inflammation, 2 pts each; other events, 1 pt each). Compliance with N in Asian pts was also improved (71% vs ITT, 61%).

Conclusions: In Asian pts enrolled into ExteNET, compliance with N was better and the magnitude of N effect was similar or greater that that observed in the ITT population. Although N-related grade 3/4 diarrhea was more common in Asian pts than in the ITT population, all other grade 3/4 events were rare. Despite small pt numbers, our analyses suggest that the findings from ExteNET are applicable to Asian pts, and support the conclusion that N reduces disease recurrences in Asian pts with early-stage HER2+ breast cancer after T-based adjuvant therapy.

Citation Format: Iwata H, Masuda N, Kim S-B, Inoue K, Rai Y, Fujita T, Shen Z-Z, Chiu JW, Ohtani S, Takahashi M, Yamamoto N, Miyaki T, Sun Q, Yen-Shen L, Xu B, Yap YS, Bustam AZ, Lee JR, Zhang B, Bryce R, Chan A. Neratinib in the extended adjuvant treatment of patients from Asia with early-stage HER2+ breast cancer after trastuzumab-based therapy: Exploratory analyses from the phase III ExteNET trial [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-13-11.

Abstract P1-13-08: Extended adjuvant neratinib/fulvestrant blocks ER/HER2 crosstalk and maintains complete responses of ER+/HER2+ tumors following treatment with chemotherapy and anti-HER2 therapy

Background: Neratinib is a potent, irreversible pan-HER tyrosine kinase inhibitor. The phase III trial ExteNET showed improved disease-free survival in patients (pts) with HER2+ breast cancer treated with neratinib vs placebo after trastuzumab-based adjuvant therapy. The benefit from neratinib appeared to be greater in pts with ER+ tumors. Thus, we sought to elucidate mechanisms that may explain the benefit from extended adjuvant therapy with neratinib in pts with ER+/HER2+ breast cancer using a human-in-mouse model that simulates the clinical outcomes seen in ExteNET.

Results: Mice with established ER+/HER2 amplified MDA-361 tumors were treated with trastuzumab (tz) + paclitaxel (pac) for 4 weeks, and then randomized to fulvestrant (fulv) ± neratinib for 4 weeks. All MDA-361 tumors exhibited a prompt and marked reduction in volume after tz/pac treatment; 10 mice achieved a complete response (CR) before receiving 'extended adjuvant' therapy with fulv (n=5) or neratinib/fulv (n=5). A CR was maintained with neratinib/fulv following tz/pac. However, mice treated with fulv alone, relapsed rapidly (p<0.05 at week 8) despite of a complete downregulation of tumor ER levels. In a second experiment, nude mice with established MDA-361 xenografts were treated with pertuzumab/tz/pac for 4 weeks. Following a CR, mice were randomized to neratinib/fulv vs. fulv. Again, mice treated with neratinib/fulv maintained a CR, while mice in the fulv alone arm exhibited tumor progressions within a week. In three ER+/HER2+ cell lines (MDA-361, BT474 and UACC893) but not in ER+/HER– MCF7 cells, treatment with neratinib induced ER reporter transcriptional activity whereas treatment with fulv resulted in an increase in HER2 phosphorylation, suggesting compensatory crosstalk between the ER and HER2 pathways. To further understand the molecular basis of this crosstalk, MDA-361 tumor-bearing mice were treated with either fulv, neratinib or the combination for 7 days, after which tumors were harvested and analyzed using a Nanostring breast cancer ER panel consisting of 196 ER-regulated genes. Compared to vehicle or fulv-treated tumors, tumors treated with neratinib alone and neratinib/fulv showed marked downregulation of cyclin D1 mRNA expression. Similarly, in MDA-361, BT474 and UACC893 cells but not in MCF7 cells, only neratinib/fulv downregulated cyclin D1, P-AKT and P-ERK. Finally, treatment with neratinib/fulv but not fulv alone reduced cyclin D1 transcriptional reporter activity and cyclin D1 protein levels, and induced cell cycle arrest, suggesting double blockade is required to overcome compensatory crosstalk between ER and amplified HER2.

Conclusions: Neratinib/fulv but not fulv alone maintained complete responses of ER+/HER+ tumors following treatment with tz/pac or pertuzumab/tz/pac, reminiscent of the results in ExteNET. Neratinib treatment promoted ER transcriptional activity whereas ER downregulation with fulv was associated with increased HER2 signaling. In ER+/HER2+ breast cancer cells and tumors, neratinib/fulv synergistically inhibited growth, cyclin D1 expression, and AKT and MAPK activation, thus providing a plausible mechanism to explain the results in the ExteNET trial.

Citation Format: Sudhan DR, Schwarz LJ, Guerrero-Zotano AL, Nixon M, Formisano L, Croessmann S, Gonzalez Ericsson PI, Sanders ME, Balko JM, Avogadri-Connors F, Cutler RE, Lalani AS, Bryce R, Auerbach A, Arteaga CL. Extended adjuvant neratinib/fulvestrant blocks ER/HER2 crosstalk and maintains complete responses of ER+/HER2+ tumors following treatment with chemotherapy and anti-HER2 therapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-13-08.

Use of multicriteria decision analysis to address conservation conflicts

Conservation conflicts are increasing on a global scale and instruments for reconciling competing interests are urgently needed. Multicriteria decision analysis (MCDA) is a structured, decision-support process that can facilitate dialogue between groups with differing interests and incorporate human and environmental dimensions of conflict. MCDA is a structured and transparent method of breaking down complex problems and incorporating multiple objectives. The value of this process for addressing major challenges in conservation conflict management is that MCDA helps in setting realistic goals; entails a transparent decision-making process; and addresses mistrust, differing world views, cross-scale issues, patchy or contested information, and inflexible legislative tools. Overall we believe MCDA provides a valuable decision-support tool, particularly for increasing awareness of the effects of particular values and choices for working toward negotiated compromise, although an awareness of the effect of methodological choices and the limitations of the method is vital before applying it in conflict situations.

Randomized, dose-finding phase III study of lithium gamolenate in patients with advanced pancreatic adenocarcinoma

BACKGROUND

Chemotherapy for pancreatic cancer offers small survival benefits and considerable side-effects. Unsaturated fatty acids have an antitumour effect in experimental studies; in phase II studies few side-effects were seen.

METHODS

In this group-sequential, open-label, randomized study, 278 patients with a diagnosis of inoperable pancreatic cancer were treated with either oral (700 mg daily for 15 days), low-dose (0.28 g/kg) or high-dose (0.84 g/kg) intravenous lithium gamolenate (LiGLA). The primary endpoint was survival time from randomization using Kaplan-Meier estimates.

RESULTS

Median survival after oral and low-dose intravenous treatment was 129 and 121 days respectively. Median survival after high-dose intravenous treatment was 94 days. A good Karnofsky score and the absence of metastases were associated with increased survival. Haemolysis, a marker of rapid infusion, was associated with a median survival time of 249 days in the low-dose intravenous group.

CONCLUSION

Oral or low-dose intravenous LiGLA led to survival times similar to those of other treatments for pancreatic cancer although one subgroup (low-dose intravenous LiGLA with haemolysis) had longer survival. High-dose intravenous treatment appeared to have an adverse effect. Systemic treatment with LiGLA cannot be recommended for the treatment of pancreatic cancer.

The effect of fatty acids and analogues upon intracellular levels of doxorubicin in cells displaying P-glycoprotein mediated multidrug resistance

Multidrug resistance mediated by overexpression of P-glycoprotein (P-gp) is a major obstacle in the chemotherapeutic management of cancer. The objectives of the current work were to examine if fatty acids affect the intracellular transport and dynamics of doxorubicin in drug-resistant cancer cell lines, and to assess if such effects were mediated through modulation of P-gp efflux pump activity. Among the range of fatty acids tested in this study, eicosapentaenoic acid diester (EPADI) increased doxorubicin accumulation [A] to 137% and retention [R] to 212% in doxorubicin-resistant MCF-7/ADR breast carcinoma cells, and [A] to 147% and [R] to 163% in vinblastine-resistant KBVI nasopharyngeal carcinoma cells. Consistent with EPADI-induced increases in intracellular doxorubicin concentrations, EPADI (10 microg/ml) sensitized MCF-7/ADR cells to the cytotoxic effects of doxorubicin (1 microg/ml) as assessed by MTT assay (viability < 50% of control), while EPADI itself displayed no cytotoxicity. The combination of EPADI (10 microg/ml) with verapamil (1 microM) resulted in a considerable increase in the [A] and [R] of the model P-gp substrate rhodamine-123 within drug-resistant cells compared to when either agent were used alone. KBV1 cells treated with combination of EPADI (10 microg/ml) and verapamil (1 microM) achieved 160% and 1120% greater [A] and [R] of rhodamine-123, respectively, compared to untreated cells. The P-gp modulatory effects of EPADI either alone, or as part of a combination with more potent inhibitors, should be further investigated.

Cytotoxic effects of two gamma linoleic salts (lithium gammalinolenate or meglumine gammalinolenate) alone or associated with a nitrosourea: an experimental study on human glioblastoma cell lines

Gamma linoleic acid (GLA) salts may exert a direct antiproliferative activity on tumor cells. The cytotoxicity is linked to the generation of conjugated dienes, peroxyl radicals and superoxide radicals. Lithium gammalinolenate (LiGLA) and meglumine gammalinolenate (MeGLA) have been recently developed for enhancing the water solubility of these compounds. MeGLA or LiGLA (10(-5) to 10(-4) mol/l) and fotemustine (Fote) (2 x 10(-6) to 2 x 10(-4) mol/l) were applied, alone or in combination, for up to 9 days to two human glioblastoma cell lines A172 and U373MG. Fote was applied first followed by LiGLA and/or MeGLA. Cytotoxicity was evaluated by the MTT test, and the effects of drug combinations were analyzed by the isobolographic representation according to the Chou and Talalay method (combination indexes). For both GLA salts, cytotoxicity was manifested after 4 days of cell exposure and with very sharp dose-response curves. Comparison of IC50 values indicated that MeGLA was more active than LiGLA. There was a constant reduction in IC50 values following an increase in exposure time for A172 cells: between 4 and 9 days of cell exposure, IC50 changed from 73 to 46 microM for LiGLA and from 49 to 31 microM for MeGLA (p<0.05). With U373MG cells, there was no influence of exposure duration on IC50 values. Combination index values indicated that association between Fote and GLA salts globally resulted in slightly antagonistic effects. These results may be useful for further development of GLA salts at the clinical level.

Calcium supplementation in nulliparous women for the prevention of pregnancy-induced hypertension, preeclampsia and preterm birth: an Australian randomized trial. FRACOG and the ACT Study Group

A multicentre, randomized controlled double-blind trial in 5 maternity hospitals in Australia assessed the effect of a daily supplement of calcium (1.8g oral calcium or an oral placebo) taken daily until delivery, from less than 24 weeks' gestation, on the frequency of pregnancy-induced hypertension, preeclampsia and preterm birth (< 37 weeks' gestation) in 456 nulliparas with a singleton pregnancy. Treatment with calcium reduced the risk of preeclampsia (relative risk 0.44 [95% CI, 0.21-0.90], p = 0.02) and the risk of preterm birth (relative risk 0.44 [95% CI, 0.21-0.90], p = 0.02). No significant differences were seen between the 2 groups in the frequency of pregnancy-induced hypertension, although the study only had statistical power to detect large differences in this outcome. An updated systematic review of the 9 randomized trials of calcium supplementation in pregnancy shows a significant reduction in the risk of hypertension and preeclampsia although no effect on preterm birth. Calcium supplementation during pregnancy reduced the risk of preeclampsia and preterm birth in this nulliparous population. The available evidence for systematic review of all the randomized trials of calcium supplementation shows benefit in reducing the risk of hypertension and preeclampsia.

Inhibition of membrane ruffling and ezrin translocation by gamma linolenic acid

Membrane ruffling of a tumour cell is correlated with its motile and metastatic behaviour. This study examined the effect of gamma linolenic acid (GLA), an anti-cancer agent, on HGF/SF induced membrane ruffling in the human cancer cell line, HT115. HGF induced a rapid appearance of membrane ruffling which was related to increased motility and the tyrosine phosphorylation and translocation of ezrin, a membrane-cytoskeleton linker protein. The presence of GLA significantly inhibited both the membrane ruffling and cell motility of the tumour cells, at sub-toxic concentrations. Western blotting revealed that the tyrosine phosphorylation of ezrin was inhibited by GLA. The translocation ezrin from cytosol and generalised areas of cell membrane to ruffled areas of the membrane induced by HGF/SF was also inhibited as shown by both indirect immunofluorescence and transmission electron microscopy. It is concluded that GLA inhibits HGF/SF induced membrane ruffling via its effect on ezrin, and this provides a further molecular explanation for the anti-tumour action of GLA.

Gamma linolenic acid inhibits tyrosine phosphorylation of focal adhesion kinase and paxillin and tumour cell matrix interaction

Gamma linolenic acid (GLA) is an anti-cancer agent recently reported to inhibit tumour cell-matrix attachment. This study examined the effects of GLA on the adhesion of two tumour cell lines, HT115 (human colon) and MDA MB 231 (human breast), to an extracellular matrix, Matrigel. The action of GLA on focal adhesion kinase(FAK) and paxillin was also investigated. Following cell adhesion to Matrigel in control experiments, both FAK and paxillin were quickly tyrosine phosphorylated and become concentrated at focal adhesion areas. Inclusion of GLA resulted in an inhibition of the tyrosine phosphorylation of both FAK and paxillin leading to a reduced attachment of both cell types to Matrigel. FAK and paxillin were also less well distributed in the focal adhesions compared with the controls. It is concluded, therefore, that GLA inhibits tumour-matrix adhesion via the inhibition of FAK and paxillin tyrosine phosphorylation.

Stiffening effects of cortical bone on vertebral cancellous bone in situ

STUDY DESIGN

This study tested a theory about vertebral cancellous bone stiffness by performing experimental tests and comparing the results with the theoretical predictions.

OBJECTIVES

To test experimentally a theoretical prediction that vertebral cancellous bone appears stiffer than would be expected from isolated tests because of the constraining effects of the cortical bone, to measure the magnitude of this strengthening effect and its dependency on tissue composition and density.

SUMMARY OF BACKGROUND DATA

Vertebral bodies are composed mainly of cancellous bone surrounded by a thin shell of much stronger cortical bone. Little is known of the ways in which these two materials function synergistically to produce strong but light structures and why sometimes extensive damage to the cancellous bone has apparently little outward effect on vertebral body strength.

METHODS

Cancellous bone from 45 lumbar vertebrae from a homogeneous group of pigs was tested in compression both in situ in the vertebral body and as an excised cylinder. The density and composition of the bone were then measured and correlation tested with both of the stiffness measurements.

RESULTS

The cancellous bone in situ appears much stiffer than when isolated by a factor of about 4 (range, 1.6-12). No correlation was found between stiffness, either in situ or in isolation, and density, although density is predicted entirely by the volume fractions of water, organic, and mineral phases.

CONCLUSIONS

Combining low density cancellous bone with stiffer, more dense cortical bone leads to a lightweight structure that is much stronger than might be expected from the isolated properties of its components.