Abstract 4347: A pivotal clinical trial of cResponse, a functional assay for cancer precision medicine

Precision cancer therapy has the potential to revolutionize treatment outcome. While genomic analysis has become central to cancer personalized medicine, recent studies have not shown that it drastically improves the patient’s survival as compared to standard drug selection. Additionally, genomic mutations may suggest several treatment protocols without elucidating which approach will yield the best clinical response. To advance cancer precision guidance, we have developed cResponse, a combined genomic-functional drug sensitivity platform to determine individualized patient treatment regimens. Fresh patient cancer samples are taken by biopsy or resection and sectioned into 250uM slices which when cultured in cResponse platform demonstrate similar architecture and tissue proliferation to those found in vivo. An initial clinical study showed that cResponse can preserve human cancer tissue in 3D culture together with its microenvironment, including endothelial and immune cells, at a high viability (>90%) with continued cell division for more than 7 days. On a cohort of 34 patients treated with neoadjuvant therapy or systemic therapy for metastatic disease, the assay was able to predict patient response to drug treatment with a sensitivity of 96% and a specificity of 77.7%. To further validate the capacity of the cResponse platform to predict patient response to cancer therapy, a follow up pivotal clinical study was established at 7 major cancer centers located in the UK with the goal of recruiting a total of 170 patients to provide a large statistical validation of the previous results. Here we report on the outcome of the first 50 patients recruited to the pivotal trial and describe the predictive results correlated to patient response.

Citation Format: Seth Salpeter, Vered Bar, Guy Neev, Adi Zundelevich, Gil Rosen, Sandra Hanks, Naoise Costelloe, Jonathan Krell, Ravid Straussman. A pivotal clinical trial of cResponse, a functional assay for cancer precision medicine. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4347.

Comparing Intraperitoneal and Intravenous Personalized ErbB2CAR-T for the Treatment of Epithelial Ovarian Cancer

High-grade serous ovarian carcinoma (HGSOC) is the most common type of epithelial ovarian cancer. The majority of cases are diagnosed at advanced stages, when intraperitoneal (IP) spread has already occurred. Despite significant surgical and chemotherapeutic advances in HGSOC treatment over the past decades, survival rates with HGSOC have only modestly improved. Chimeric antigen receptor (CAR)-T cells enable T cells to directly bind to tumor-associated antigens in a major histocompatibility complex-independent manner, thereby inducing tumor rejection. While CAR-T cell therapy shows great promise in hematological malignancies, its use in solid tumors is limited. Therefore, innovative approaches are needed to increase the specificity of CAR-modified T cells against solid tumors. The aim of this study was to assess the efficacy and safety of intraperitoneal (IP) versus intravenous (IV) CAR-T cell therapy in the treatment of HGSOC. We constructed a CAR that targets the ErbB2/HER2 protein (ErbB2CAR), which is overexpressed in HGSOC, and evaluated the functionality of ErbB2CAR on ovarian cancer cell lines (OVCAR8, SKOV3, and NAR). Our findings show that an IP injection of ErbB2CAR-T cells to tumor-bearing mice led to disease remission and increased survival compared to the IV route. Moreover, we found that IP-injected ErbB2CART cells circulate to a lesser extent, making them safer for non-tumor tissues than IV-injected cells. Further supporting our findings, we show that the effect of ErbB2CAR-T cells on primary HGSOC tumors is correlated with ErbB2 expression. Together, these data demonstrate the advantages of an IP administration of CAR-T cells over IV administration, offering not only a safer strategy but also the potential for counteracting the effect of ErbB2CAR in HGSOC. Significance: IP-injected ErbB2CAR-T cells led to disease remission and increased survival compared to the IV route. These findings demonstrate the advantages of IP administration, offering a safe treatment strategy with the potential for counteracting the effect of ErbB2CAR in HGSOC.

Abstract P1-08-25: Evaluating an ex vivo organ culture system for predicting response to neoadjuvant chemotherapy in breast cancer patients

Background. Neoadjuvant chemotherapy (NACT) is increasingly administered for high-risk breast cancer patients. Yet, oncologists lack an effective method for assessing response to treatment beyond clinicpathological features. Organ tissue slices freshly obtained from the tumor and incubated in appropriate media, recapitulate the tumor’s heterogeneity and may provide a superior ex-vivo model for predicting response/resistance to treatment. While these models were tested in metastatic tumors, no studies up to date have been reported in early breast cancer or for NACT. These tests have short turnaround time (7-9 days), critical for the neoadjuvant setting. Here we aimed to prove the feasibility of performing cResponse assay, an ex vivo organ culture (EVOC), on freshly derived pre-treatment core needle biopsies and to evaluate it as a tool for predicting response to NACT in breast cancer. Methods. Pre-treatment tumor biopsies were obtained from breast cancer patients about to undergo NACT at the time of routine tumor clip marking. The fresh samples were immediately placed in cold medium, sliced into 250um sections and cultured in multiwell plates. The samples were treated with the clinically administered therapies or a vehicle control. The various therapies included Doxorubicin (A), Paclitaxel (T), Cytoxan (C) and in TN cases, Carboplatin (Cr), as single agents or in combination in clinically administered ratios. After 4 days of treatment, tumor slices were fixed and stained to allow morphological analysis. A trained pathologist examined the stained slides and scored the viable cancer cells. A response-score was generated and compared to the pathological result (pCR status and RCB class) of the patient at surgery.Results. Tumor samples from 15 breast cancer patients were examined. The cohort median age was 42 (32—82), LN involvement 9/15, subtypes status: 9 HR+, 2 TNBC, 3 HR+HER2+ and 1 HR-HER2+. Nine samples were either excluded due to insufficient viable cancer cells or necrosis and one sample failed technically. Five samples (2 TNBC, 2 HR+ and 1 HR+HER2+) were adequate for analysis and obtained cResponse scores. The HR+HER2+ case received a different protocol than actually tested, thus was not compared. For the four successful cases, the cResponse score was highly concordant with response to therapy (Table I). For the two TNBC samples, a maximal cResponse score (100) was demonstrated for AC-T or AC-TC combination and both patients achieved complete response (pCR, RCB-0) at surgery. Notably, in one patient, the assay predicted maximal response for the TC combination, suggesting that this protocol could be sufficient. For the HR+ patients, one patient demonstrated a strong cResponse to AC-T (85) and achieved near complete response (RCB-I), while the second patient demonstrated a moderate cResponse score (70) and achieved partial pathological response (RCB-II). Conclusions. We provide initial evidence for the feasibility and validity of an EVOC platform to predict response to NACT in breast cancer. Further optimizations are needed to increase the assay’s success rates. We expect the results to set the ground for a clinical trial, examining the utility of the cResponse test as predictive biomarker in determining NACT. This technology may provide a tool for the oncologist to select the most efficient therapies, maximizing pCR rates and minimizing toxicity from ineffective drugs, eventually improving prognosis of breast cancer patients.

Table IPatientSubtypeBest cResponse scoreBest treatmentsPathological ResponseRCB classNAT-2HR+70AC-T/AC/CPartialRCB-IINAT-3TN100AC-TCr/TCrpCRRCB-0NAT-12TN100A/AC-TpCRRCB-0NAT-16HR+85AC-TPartialRCB-I

Citation Format: Einav Nili Gal-Yam, Miri Sklair-Levi, Yaeli Vachnish, Nora Balint-Lahat, Dana Morzaev-Sulzbach, Michal Bakalenik-Gavry, Renata Fearmann, Osnat Halshtok, Anat Shalmon, Michael Gotlieb, Yael Yagil, Keren Levanon, Rinat Bernstein-Molho, Amit Itay, Tali Shapira-Rotenberg, Opher Globus, Iris Barshack, Seth Salpeter, Vered Bar, Sara Aharon, Lubov Turovsky, Adi Zundelevich, Giuseppe Mallel, Hamutal Shahar, Hagit Shapira, Maya Dadiani. Evaluating an ex vivo organ culture system for predicting response to neoadjuvant chemotherapy in breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-25.

Abstract CT209: A clinical trial of cResponse, a functional assay for cancer precision medicine

Precision cancer therapy has the potential to revolutionize treatment outcome. While genomic analysis has become central to cancer personalized medicine, recent studies have not shown that it drastically improves patient survival as compared to standard drug selection. Additionally, genomic mutations may suggest several treatment protocols without elucidating which approach will yield the best clinical response. Moreover, for many drugs no genetic predictive biomarkers are available. To advance cancer precision diagnostics, we have developed cResponse, a functional drug sensitivity platform to determine individualized patient treatment regimens. Fresh patient cancer samples are taken by biopsy or resection and sectioned into 300 uM slices which when cultured in the cResponse platform demonstrate similar architecture and tissue proliferation to those found in vivo. We show that cResponse is able to preserve human cancer tissue in 3D together with its microenvironment, including endothelial and immune cells, at a high viability (>90%) with continued cell division for 7 days in over twenty types of solids tumors. Importantly, the high viability of the tissue over an extended period of time allows for a rapid genomic profiling to help prioritize drugs to be tested by cResponse, as well as the capacity to evaluate the effects of slow acting drugs such as targeted therapy. To validate the capacity of the cResponse platform to predict patient response to cancer treatment, forty two patients with different cancer types receiving diverse chemotherapeutic and targeted agents were recruited to the study and their tumors were tested using cResponse prior to initiation of treatment. Cancer types included bladder, pancreatic, lung, colorectal, breast and sarcoma. After five days of treatment ex-vivo, the samples were fixed and designated a viability score (ranging from 0 to 100) based on an algorithm composed of a panel of histological and morphological markers. The cResponse score was compared to the clinical response to treatment of 27 patients for which this data is already available. The results demonstrated that cResponse could predict the patient's response with a specificity of 82% (9/11) and a sensitivity of 93.75% (15/16) when compared to the patient's imaging results. In the future, the integration of this platform in directing anti-cancer treatment may lead to better response rate of cancer patients to therapy.

Citation Format: Seth Salpeter, Vered Bar, Sara Aharon, Luba Torovsky, Adi Zundelevich, Hamutal Shachar, Hagit Shapira, Nancy Gavert, Ravid Straussman, Shay Golan, Eli Rosenbaum, Talia Golan, Raanan Berger, Zohar Dotan, Dan Leibovici, Shani Breuer, Yakir Rotenberg, Aviad Zick, Ayala Hubert, Hovav Nechushtan, Guy Neev. A clinical trial of cResponse, a functional assay for cancer precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT209.

Cathepsin Inhibition Modulates Metabolism and Polarization of Tumor-Associated Macrophages

Simple Summary

Stroma-infiltrating tumor-associated macrophages (TAM) play an important role in regulating tumor progression and chemoresistance. Many tumor-infiltrating macrophage populations can be identified by preferential expression of distinct marker genes associated with an M2 phenotype and may execute tumor-promoting functions by enhancing tissue remodeling, facilitating angiogenesis, and suppressing immune responses. In this study, we aimed to characterize the impact of cathepsins in maintaining the TAM phenotype. For this purpose, we investigated the molecular effects of cathepsin inhibition on the viability and polarization of human primary macrophages as well as its metabolic consequences. Pharmacological inhibition of cathepsins B, L, and S using a novel inhibitor, GB111-NH₂, led to a polarization shift from M2- to M1 macrophages, associated with distinct alterations in lysosomal signaling and lipid metabolism. This could be therapeutically exploited in tumors with strong infiltration of M2-macrophages, thereby possibly reverting M2 polarization, overcoming drug resistance, and improving the prognosis of our patients.

Abstract

Stroma-infiltrating immune cells, such as tumor-associated macrophages (TAM), play an important role in regulating tumor progression and chemoresistance. These effects are mostly conveyed by secreted mediators, among them several cathepsin proteases. In addition, increasing evidence suggests that stroma-infiltrating immune cells are able to induce profound metabolic changes within the tumor microenvironment. In this study, we aimed to characterize the impact of cathepsins in maintaining the TAM phenotype in more detail. For this purpose, we investigated the molecular effects of pharmacological cathepsin inhibition on the viability and polarization of human primary macrophages as well as its metabolic consequences. Pharmacological inhibition of cathepsins B, L, and S using a novel inhibitor, GB111-NH₂, led to changes in cellular recycling processes characterized by an increased expression of autophagy- and lysosome-associated marker genes and reduced adenosine triphosphate (ATP) content. Decreased cathepsin activity in primary macrophages further led to distinct changes in fatty acid metabolites associated with increased expression of key modulators of fatty acid metabolism, such as fatty acid synthase (FASN) and acid ceramidase (ASAH1). The altered fatty acid profile was associated with an increased synthesis of the pro-inflammatory prostaglandin PGE₂, which correlated with the upregulation of numerous NF_kB-dependent pro-inflammatory mediators, including interleukin-1 (IL-1), interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2), and tumor necrosis factor-alpha (TNFα). Our data indicate a novel link between cathepsin activity and metabolic reprogramming in macrophages, demonstrated by a profound impact on autophagy and fatty acid metabolism, which facilitates a pro-inflammatory micromilieu generally associated with enhanced tumor elimination. These results provide a strong rationale for therapeutic cathepsin inhibition to overcome the tumor-promoting effects of the immune-evasive tumor micromilieu.

A novel quenched fluorescent activity-based probe reveals caspase-3 activity in the endoplasmic reticulum during apoptosis

A selective quenched activity-based probe detects caspase-3 activity in the endoplasmic reticulum of cancerous cells during apoptosis.

The caspases are a family of cysteine proteases that are key regulators of apoptosis and their activity may thus serve as a good marker to monitor cell death. We have developed a quenched fluorescent activity-based probe (qABP) that is selective for caspase-3 activity and emits a fluorescent signal after covalently modifying its target. The probe has a wide range of potential applications, e.g. in real-time imaging, FACS analysis or biochemical quantification of caspase activity in intact cells. Application of the probe allowed us to monitor caspase-3 activation after chemotherapy-treatment and to distinguish between apoptosis sensitive and resistant cells. Moreover, it enabled real-time high-resolution visualization of active caspase-3 during apoptosis. This led to the surprising finding that in cancerous cells active caspase-3 is not only found at the familiar cellular locations but also in mitochondria and the endoplasmic reticulum. Thus, our novel covalent probe allows high spatial and temporal resolution imaging of caspase-3 activation and may thus be used as an effective tool to study molecular mechanisms of programmed cell death in healthy and disease states.

G0-G1 transition and the restriction point in pancreatic β-cells in vivo

Most of our knowledge on cell kinetics stems from in vitro studies of continuously dividing cells. In this study, we determine in vivo cell-cycle parameters of pancreatic β-cells, a largely quiescent population, using drugs that mimic or prevent glucose-induced replication of β-cells in mice. Quiescent β-cells exposed to a mitogenic glucose stimulation require 8 h to enter the G1 phase of the cell cycle, and this time is prolonged in older age. The duration of G1, S, and G2/M is ~5, 8, and 6 h, respectively. We further provide the first in vivo demonstration of the restriction point at the G0-G1 transition, discovered by Arthur Pardee 40 years ago. The findings may have pharmacodynamic implications in the design of regenerative therapies aimed at increasing β-cell replication and mass in patients with diabetes.

Short-term overexpression of VEGF-A in mouse beta cells indirectly stimulates their proliferation and protects against diabetes

AIMS/HYPOTHESIS

Vascular endothelial growth factor (VEGF) has been recognised by loss-of-function experiments as a pleiotropic factor with importance in embryonic pancreas development and postnatal beta cell function. Chronic, nonconditional overexpression of VEGF-A has a deleterious effect on beta cell development and function. We report, for the first time, a conditional gain-of-function study to evaluate the effect of transient VEGF-A overexpression by adult pancreatic beta cells on islet vasculature and beta cell proliferation and survival, under both normal physiological and injury conditions.

METHODS

In a transgenicmouse strain, overexpressing VEGF-A in a doxycycline-inducible and beta cell-specific manner, we evaluated the ability of VEGF-A to affect islet vessel density, beta cell proliferation and protection of the adult beta cell mass from toxin-induced injury.

RESULTS

Short-term VEGF-A overexpression resulted in islet hypervascularisation, increased beta cell proliferation and protection from toxin-mediated beta cell death, and thereby prevented the development of hyperglycaemia. Extended overexpression of VEGF-A led to impaired glucose tolerance, elevated fasting glycaemia and a decreased beta cell mass.

CONCLUSIONS/INTERPRETATION

Overexpression of VEGF-A in beta cells time-dependently affects glycometabolic control and beta cell protection and proliferation. These data nourish further studies to examine the role of controlled VEGF delivery in (pre)clinical applications aimed at protecting and/or restoring the injured beta cell mass.

A mouse model for sleeve gastrectomy: applications for diabetes research

INTRODUCTION

Discovery of enhanced glucose tolerance following bariatric surgery has sparked renewed interest in the investigation of unchartered underlying pathways of glucose homeostasis. Delineation of this pathway may ultimately be the first step in the creation of a novel therapy for type II diabetes. Nevertheless, the technical complexity and formidable nature of these surgeries coupled with the fragile nature of small rodents has made the creation of a mouse model to study these effects incredibly challenging. We have created a simplified sleeve gastrectomy mouse model to study the effects of bariatric surgery on glucose tolerance and beta cell proliferation.

METHODS

Nineteen mice were randomized to undergo either sleeve gastrectomy (SG) (9) or sham operation (SH) (10). Weight and serum glucose were measured three times weekly and serum insulin measurements and pancreatic harvest were performed at the time of sacrifice. Five mice from each group were sacrificed after one week and the remainder sacrificed after one month.

RESULTS

Survival of mice was 100% for both groups. The SG group demonstrated an initial drop in weight and serum glucose as compared to SH, which normalized by one month following surgery. Serum insulin levels and rate of beta cell proliferation were similar in both groups after one week and one month.

CONCLUSION

The simplified sleeve gastrectomy is a technically straightforward, low-mortality technique for creating a bariatric mouse model which most faithfully replicates bariatric surgery performed in humans. This model can be a valuable tool to investigate the glucose tolerance and beta cell effects of bariatric surgery.

Determinants of pancreatic beta-cell regeneration

Recent studies have revealed a surprising plasticity of pancreatic beta-cell mass. beta-cell mass is now recognized to increase and decrease in response to physiological demand, for example during pregnancy and in insulin-resistant states. Moreover, we and others have shown that mice recover spontaneously from diabetes induced by killing of 70-80% of beta-cells, by beta-cell regeneration. The major cellular source for new beta-cells following specific ablation, as well as during normal homeostatic maintenance of adult beta-cells, is proliferation of differentiated beta-cells. More recently, it was shown that one form of severe pancreatic injury, ligation of the main pancreatic duct, activates a population of embryonic-type endocrine progenitor cells, which can differentiate into new beta-cells. The molecular triggers for enhanced beta-cell proliferation during recovery from diabetes and for activation of embryonic-type endocrine progenitors remain unknown and represent key challenges for future research. Taken together, recent data suggest that regenerative therapy for diabetes may be a realistic goal.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A search was performed of The Cochrane Library (up to 8/2005), MEDLINE (up to 8/2005), EMBASE (up to 11/2000), OLD MEDLINE, and REACTIONS (up to 8/2005), in order to identify all studies of metformin treatment from 1966 to August 2005. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: August 2005.

SELECTION CRITERIA

Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effect model for continuous data.

MAIN RESULTS

Pooled data from 206 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 47,846 patient-years of metformin use or in 38,221 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 6.3 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 7.8 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15).

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions.

Cardioselective beta-blockers for chronic obstructive pulmonary disease

BACKGROUND

Beta-blocker therapy has a proven mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To assess the effect of cardioselective beta-blockers on respiratory function of patients with COPD.

SEARCH STRATEGY

A comprehensive search of the Cochrane Airways Group Specialised Register (derived from systematic searches of CENTRAL, MEDLINE, EMBASE and CINAHL) was carried out to identify randomised blinded controlled trials from 1966 to May 2005. We did not exclude trials on the basis of language.

SELECTION CRITERIA

Randomised, blinded, controlled trials of single dose or longer duration that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 second (FEV1) or symptoms in patients with COPD.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data from the selected articles, reconciling differences by consensus. Two interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta2-agonist given after the study drug.

MAIN RESULTS

Eleven studies of single-dose treatment and 9 of treatment for longer durations, ranging from 2 days to 12 weeks, met selection criteria. Cardioselective beta-blockers, given as a single dose or for longer duration, produced no change in FEV1 or respiratory symptoms compared to placebo, and did not affect the FEV1 treatment response to beta2-agonists. A subgroup analysis revealed no change in results for those participants with severe chronic airways obstruction or for those with a reversible obstructive component.

AUTHORS' CONCLUSIONS

Cardioselective beta-blockers, given to patients with COPD in the identified studies did not produce adverse respiratory effects. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should not be routinely withheld from patients with COPD.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A search was performed of the Cochrane Controlled Trials Register and the Database of Abstracts of Reviews of Effectiveness (up to 4/2000), Medline (up to 11/2000), Embase (up to 11/2000), Oldmedline, and Reactions (up to 5/2000), in order to identify all studies of metformin treatment from 1966 to November 2000. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: November 2000.

SELECTION CRITERIA

Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effects model for continuous data.

MAIN RESULTS

Pooled data from 176 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 35,619 patient-years of metformin use or in 30,002 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 8.4 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 9 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15).

REVIEWER'S CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions, taking into account contra-indications.

Cardioselective beta-blocker use in patients with reversible airway disease

BACKGROUND

Beta-blocker therapy has mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with reversible airway disease.

OBJECTIVES

To assess the effect of cardioselective beta-blockers on respiratory function of patients with reversible airway disease. Reversible airway disease was defined as asthma or chronic obstructive pulmonary disease with a reversible obstructive component.

SEARCH STRATEGY

A comprehensive search of EMBASE, MEDLINE and CINAHL was performed using the Cochrane Airways Group registry to identify randomized blinded placebo-controlled trials from 1966 to February, 2000. The search was completed using the terms: asthma*, bronchial hyperreactivity*, respiratory sounds*, wheez*, obstructive lung disease* or obstructive airway disease*, and adrenergic antagonist*, sympatholytic* or adrenergic receptor block*. We did not exclude trials on the basis of language.

SELECTION CRITERIA

Randomized, blinded, placebo-controlled trials of single dose or longer duration that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 second (FEV1), symptoms and use of short-acting inhaled beta-agonists, in patients with reversible airway disease. Reversible airway disease was documented by response to methacholine challenge, by an increase in FEV1 of at least 15% to beta-agonist administration, or the presence of asthma as defined by the American Thoracic Society.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data from the selected articles, reconciling differences by consensus. Cardioselective beta-blockers were divided into 2 groups, those with or without intrinsic sympathomimetic activity (ISA). Two interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta-agonist given after the study drug.

MAIN RESULTS

Nineteen studies for single-dose treatment and 10 for treatment of longer duration met selection criteria. The patients had mild-moderate airways obstruction. For cardioselective beta-blockers taken as a group, administration of a single dose was associated with a 7.98% (CI, 6.19 to 9.77%) reduction in FEV1, but with a 13.16% (CI, 10.76 to 15.56%) increase in beta-agonist response, as compared to placebo. There was no increase in symptoms. After treatment lasting a few days to a few weeks, there was no decrement in FEV1 compared to placebo and no increase in symptoms or inhaler use. Regular use of cardioselective beta-blockers without ISA produced a 13.13% (CI, 5.97 to 20.30) increase in beta-agonist response compared to placebo, a response not seen with beta-blockers containing ISA (-0.60% [CI, -11.7 to +10.5%]).

REVIEWER'S CONCLUSIONS

Cardioselective beta-blockers, given to patients with mild-moderate reversible airway disease, do not produce clinically significant adverse respiratory effects in the short term. It is not possible to comment on their effects in patient with more severe or less reversible disease, or on their effect on the frequency or severity of acute exacerbations. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should not be withheld from patients with mild-moderate reversible airway disease.

Tuberculosis chemoprophylaxis

The incidence of tuberculosis in the United States, after decreasing for many years, has recently begun to climb at an alarming rate. This rise is due mainly to excess cases in high-risk groups including human immunodeficiency virus-infected patients, the elderly, the foreign born, and the homeless. In the United States tuberculosis has been associated with a 10% mortality despite adequate treatment. The tuberculin skin test is a safe and inexpensive test for detecting tuberculous infection. To improve its predictive value the diagnostic criteria for classifying a positive reaction have recently been revised. High-risk populations should be screened to identify those persons who would most benefit from preventive treatment. Isoniazid therapy taken for 6 to 12 months is a safe and highly effective means of preventing tuberculous infection from developing into active disease. The most worrisome toxicity of isoniazid, fatal hepatitis, is extremely rare; when patients are monitored closely the incidence of death from hepatotoxicity is less than 0.01%.