Imatinib plasma levels in patients with gastrointestinal stromal tumour under routine clinical practice conditions

OBJECTIVES

Imatinib is the first therapeutic option for the treatment of unresectable or metastatic gastrointestinal stromal tumours. Previous studies have shown an improvement in patient survival rates following the use of imatinib. Nevertheless, adequate plasma concentrations of imatinib are necessary to achieve such improvement in survival and limit the toxicity of the drug. This study aims to analyse the influence of imatinib plasma concentrations on efficacy and safety in the treatment of gastrointestinal stromal tumour.

MATERIALS AND METHODS

This descriptive, multicentre study analysed plasma levels of imatinib in patients diagnosed with gastrointestinal stromal tumour in the period 2019-2020. An optimal therapeutic range of 750-1500 ng/mL was established for the patient stratification based on their minimum plasma concentrations measured at the steady state.

RESULTS

This study included 11 patients with metastatic disease in total, among whom only 54.5% (n  =  6) had a minimum plasma concentrations measured at the steady state value within the therapeutic range. A median progression-free survival of 7.0 months was recorded for those patients with minimum plasma concentrations measured at the steady state < 750 ng/mL, while that median progression-free survival value remained unachieved for the group with minimum plasma concentrations measured at the steady state > 750 ng/mL (p  =  0.005). The toxicity rate was 25% and 14.3% for patients with minimum plasma concentrations measured at the steady state > 1500 ng/mL and minimum plasma concentrations measured at the steady state ≤1500 ng/mL, respectively (p  =  0.66).

CONCLUSIONS

The present study aims to describe the correlation between the toxicity and effectiveness of imatinib as a function of minimum plasma concentrations measured at the steady state under routine clinical practice conditions. The results described here show the usefulness of imatinib plasma concentrations monitoring as part of the standard daily routine in our hospitals.

Imatinib plasma levels in patients with chronic myeloid leukaemia under routine clinical practice conditions

INTRODUCTION

The addition of imatinib to the therapeutic arsenal for chronic myeloid leukaemia (CML) has changed the natural course of the disease, in such a way that it is now considered a chronic pathology. However, to achieve therapeutic success, it is necessary to reach adequate plasma concentrations to ensure efficacy and safety.In this study, we aimed to evaluate the plasma concentration of imatinib, analysing its influence on effectiveness and safety in patients with CML.

METHODS

We performed a descriptive, multicentre study in which imatinib plasma levels from patients diagnosed with CML between 2019-2020 were analysed. An optimal therapeutic range of 750-1500 ng/mL was established for the stratification of patients, according to their minimum plasma concentrations measured at steady state (Cssmin).

RESULTS

A total of 28 patients were included, of whom only 39.3% (n = 11) showed Cssmin within the therapeutic range. 100% of patients with Cssmin >750 ng/mL achieved an optimal molecular response, while only 50% of patients with Cssmin <750 ng/mL achieved an optimal molecular response (p = 0.0004). The toxicity rate was 36.4% for patients with Cssmin >1500 ng/mL and 5.9% for those with Cssmin <1500 ng/mL (p = 0.039).

CONCLUSIONS

This study aimed to describe the correlation between the toxicity and effectiveness of imatinib according to its Cssmin in routine clinical practice conditions. Based on our findings, it would be certainly justified to monitor patient plasma concentrations of imatinib on a daily routine basis in our hospitals.

Assessment of exposure-response relationship for bevacizumab in patients with metastatic colorectal cancer

Limited literature is available for bevacizumab exposure-response relationship and there is not a concentration threshold associated with an optimal disease control. This prospective observational study in patients with metastatic colorectal cancer (mCRC) aims to evaluate, in a real-life setting, the relationship between bevacizumab through concentrations at steady state (C_{trough, SS}) and disease control. C_{trough, SS} were drawn, coinciding with the radiological evaluation of the response (progression or clinical benefit). Generalized estimating equations (GEE) analysis was performed. To test the association between C_{trough, SS} in each patient with overall survival (OS) or progression-free survival (PFS), Cox proportional hazard models were developed. Data included 50 bevacizumab C_{trough, SS} from 27 patients. The GEE model did not suggest any positive association between bevacizumab C_{trough, SS} and clinical benefit (OR 0.99, 95% CI: 0.98-1.02, p = 0.863). The Cox regression showed association between higher median C_{trough, SS} with better OS (HR 0.86, 95% CI: 0.73-1.01, p = 0.060), but not with PFS. We cannot confirm a relationship between bevacizumab C_{trough, SS} and clinical benefit but this is the first real-world study trying to show a relationship between bevacizumab C_{trough, SS} and disease control in mCRC. It was conducted in a small sample size which reduces the level of evidence. Further controlled randomized studies with a sufficient number of patients are required.

Patient-reported outcomes and digital literacy of patients treated in an oncology day hospital unit

INTRODUCTION

Patient-reported outcomes (PROs) use, via a computer registry, allows patients to report their symptoms enabling the detection of early signs of progression of the disease. For such a record, the patient needs to show certain skills in new technologies use. The present study aimed to analyse the perception and degree of digital literacy of patients undergoing oncological treatment in an Oncology Day Hospital (ODH).

METHODS

A cross-sectional descriptive study was performed, where the degree of literacy of patients attending antineoplastic treatment at the ODH was examined by means of an anonymous survey.

RESULTS

A total of 122 patients have been included in the study. The proportion of subjects who use the electronic mail (TM) and the Internet on a daily basis was 45.1% and 70.5%, respectively, and up to 77.9% from the subjects considered that the use of digital 2.0 strategies could help improve communication between healthcare professional and patient.The TM was determined by the age, educational level and employment status of the individual. Furthermore, the age of the patients conditioned their perception of the usefulness of the web 2.0 tools (T2.0).

CONCLUSION

This study allowed us to establish a target patient profile to conduct the efficient monitoring of cancer progression by PROs. The results have shown that approximately 60% of the patients in our population could be potential candidates to receive PROs-based health care. This approach enables earlier detection of symptoms and signs of progression and consequently, improves health outcomes for cancer patients.

Anti-drug antibodies anti-trastuzumab in the treatment of breast cancer

INTRODUCTION

Trastuzumab is a monoclonal antibody which could induce the activation of a humoral immune response generating anti-drug antibodies (ADAs). Such response depends of the protein nature and the route of administration (intravenous or subcutaneous). The formation of these antibodies could block the action of trastuzumab (ADA-Tras) and forming immune complexes which decrease its efficacy, so it would be interesting to determine the presence of ADA-Tras in patients treated with trastuzumab.

MATERIAL AND METHODS

The blood samples were centrifuged to separate the plasma. The presence of ADA-Tras in plasma was determined using an ELISA-type automated immunoassay.

RESULTS

Fifty-one women with non-metastatic HER2-positive breast cancer treated with trastuzumab were included. Two groups were studied: patients treated intravenously and subcutaneously. In neither case was there any presence of ADA-Tras.

DISCUSSION

This study may be the first ever conducted under usual clinical practice conditions to detect the presence of ADA-Tras in patients with non-metastatic HER2-positive breast cancer. We have wanted to show the antibodies anti-trastuzumab determination as a possible tool that would enable comparison of potential differences in immunogenic behavior between trastuzumab and its biosimilars.

Extended enzymatic stability of reconstituted lyophilized PEG-asparaginase in vials

Asparaginase (ASNase) use as a tumour-inhibitor drug has changed completely the natural course of paediatric acute lymphoblastic leukaemia (ALL) in such a way that it represents a paradigm shift in ALL management. ASNase treatment emergence has significantly improved pathologic responses and increased survival rates of ALL patients. Although different ASNase forms are currently available, only the pegylated form (PEG-ASNase) is recommended by relevant clinic guides. PEG-ASNase form shows longer elimination half-life, reducing the number of administrations, along with an enhanced safety profile. In spite of all of these advantages, PEG-ASNase elevated cost limits enormously its use. PEG-ASNase is commercialised as a lyophilised powder which according to the manufacturer it is stable for 24 hours once reconstituted, as a result, the leftover is usually discarded. In this study we analysed the enzymatic stability of reconstituted PEG-ASNase after conservation in three different temperature conditions for 5 and 14 days, aiming to take advantage of the remaining leftover for the subsequent administration. Our results have shown that PEG-ASNase is stable at 4°C, -20°C and -80°C for at least 14 days, retaining the 95% from the initial enzymatic activity in all three storage temperatures. According to our results, it is feasible to reuse the remaining content of PEG-ASNase vial after reconstitution, which means a 50% reduction of its cost for paediatric patient treatment and, consequently, removes the main barrier to use this drug in a wider population.

Pharmacokinetics of Trastuzumab After Subcutaneous and Intravenous Administration in Obese Patients

Background: Subcutaneous trastuzumab (T-SC) administration does not allow the historical target concentration of 20 µg/mL for efficacy to be reached, from the start of treatment in patients with a body mass index (BMI) >30 kg/m². Objectives: To analyze the influence of the strategy of dosification (fixed vs adjusted patient's body weight dose) on the initial minimum plasma concentration (C_min) of trastuzumab in obese patients. Methods: This was an observational, prospective study, which included patients with HER2-positive nonmetastatic breast cancer treated with trastuzumab. The determination of the C_min of trastuzumab was performed on day +21 of the first cycle using the ELISA technique. Patients were stratified according to the strategy of dosification and BMI. Results: A total of 50 patients were included; 16 patients received the drug intravenously and 34 in a fixed dosage subcutaneous (T-SC) regimen. The proportion of patients who achieved an adequate plasma concentration since the beginning of treatment was significantly higher when the drug was administered intravenously (93.8% vs 67.6%, P = 0.042). These differences are especially greater in T-SC patients with BMI >30 kg/m², with only 20% of patients exceeding the pharmacokinetic target. Conclusion and Relevance: Our study suggests that trastuzumab SC fixed dose of 600 mg is not equivalent to IV administration, especially in obese patients. An adequate trastuzumab exposure in this population needs patient weight-adjusted IV dosage in the first administration. The clinical relevance of these findings remains to be elucidated, and further research, including larger controlled trials, is warranted.

Influence of Anthropometric Characteristics in Patients With Her2-Positive Breast Cancer on Initial Plasma Concentrations of Trastuzumab

Background: Plasma concentrations of trastuzumab <20 µg/mL in patients with gastric cancer are associated with reduced progression-free and overall survival. In breast cancer treatment, this relationship has not yet been studied, but a suboptimal pharmacodynamic exposure to trastuzumab could be a reason for therapeutic failure of treatment of HER2-positive breast cancer. Objective: The objective of the present study was to determine the proportion of nonmetastatic HER2-positive breast cancers that do not reach a minimum plasma concentration ( Cmin) of 20 µg/mL after first drug administration, established as therapeutically effective in clinical trials. The secondary objective was to identify the physiological and anthropometric characteristics that determine interindividual pharmacokinetic variability. Methods: Serum concentrations of trastuzumab were assessed by ELISA on day 1 of the second cycle before administration of the second dose ( Cmin). Results: Of 19 patients included, 9 (47.4%) had a mean Cmin of 19.0 µg/mL (±12.1) after the first administration. Body mass index (BMI) and weight was the main variable that determined the achievement of therapeutic levels after the first administration. Thus, the proportion of patients reaching the target concentration was 89% when BMI was ≤30 kg/m2 but only 11% when BMI was >30 kg/m2 ( P < 0.01). Conclusions: The standard dose of 600 mg subcutaneous trastuzumab did not ensure adequate pharmacodynamic exposure from the first administration in 52% of patients, with weight and BMI being related to the plasma levels obtained.

Description of alpha-1-antitrypsin deficiency associated with PI*Q0ourém allele in La Palma Island (Spain) and a genotyping assay for its detection

By analysis of a case of discrepancy between serum alpha-1-antitrypsin (AAT) level and genotype for the most common defective alleles associated with AAT deficiency (PI*S and PI*Z), a patient carrying the allele PI*Q0ourém has been identified for the first time outside of Portugal. This null allele has been implicated in cases of severe pulmonary emphysema. After developing a clinical assay for detection of c.1130insT mutation, based on fluorescent probes (HybProbe®), another 4 carriers of PI*Q0ourém allele were identified among 43 patients with abnormally low serum AAT levels based on their genotypes for PI*S and PI*Z alleles. Since 4 out 5 cases are from the same locality (La Palma Island, Spain), it is advisable to conduct genetic analyses of affected families and, possibly, a focused population screening.

A practical route to partially protected pyrrolidines as precursors for the stereoselective synthesis of alexines

Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by sodium azide in DMF, respectively. Compound 6b was also prepared from 4b in one step by the Mitsunobu methodology. Deacetonation of 6a and 6b gave the partially protected free azidouloses 8a and 8b, respectively, that were protected as their 1-O-TBDPS derivatives 9a and 9b. Hydrogenation of 9b over Raney nickel gave stereoselectively (2R,3R,4R,5S)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (12) which was identified by transformation into the well known (2R,3R,4R,5S)-3,4-dihydroxy-2,5-bis(hydroxymethyl)pyrrolidine (1, DGDP).