Beyond hands-on and hands-off: supervisory approaches and entrustment on the inpatient ward

CONTEXT

The concept of entrustment has garnered significant attention in medical specialties, despite variability in supervision styles and entrustment decisions. There is a need to further study the enactment of supervision on inpatient wards to inform competency-based assessment design.

METHODS

Attending physicians, while supervising on clinical teaching inpatient wards, were invited to describe a recent moment of enacting supervision with an internal medicine resident. Constructivist grounded theory guided data collection and analysis. Interview transcripts were analysed in iterative cycles to inform data collection. Constant comparison was used to build a theory of supervision from the identified themes.

RESULTS

In 2016-2017, 23 supervisors from two Canadian universities with supervision reputations ranging from very involved to less involved participated in one or two interviews (total: 28). Supervisors were not easily dichotomised into styles based on behaviour because all used similar oversight strategies. Supervisors described adjusting between 'hands-on' (e.g. detail oriented) and 'hands-off' (e.g. less visible on ward) styles depending on the context. All also contended with the competing roles of clinical teacher and care provider. Supervisors made a distinction between the terms `entrust' and `trust', and did not grant complete entrustment to senior residents.

CONCLUSIONS

We propose that a supervisor's perceived responsibility for the ward underlies adjustments between 'hands-on' (i.e. personal ward responsibility) and 'hands-off' (i.e. shared ward responsibility) styles. Our approaches to clinical supervision model combines this responsibility tension with the tension between patient care and teaching to illustrate four supervisory approaches, each with unique priorities influencing entrustment. Given the fluidity in supervision, documenting changes in oversight strategies, rather than absolute levels of entrustment, may be more informative for assessment purposes. Research is needed to determine if there is sufficient association between the supervision provided, the entrustment decision made and the supervisor's trust in a trainee to use these as proxies in assessing a trainee's competence.

P1-12-13: Comparative Pharmacokinetics (PK) of Trastuzumab Emtansine (T-DM1) in Patients Who Have or Who Have Not Received Prior Treatment for Human Epidermal Growth Factor 2 (HER2)-Positive Metastatic Breast Cancer (MBC)

Background: T-DM1, an antibody-drug conjugate composed of trastuzumab, a stable linker, and the cytotoxic agent DM1, is in development for the treatment of HER2−positive cancers. Single-agent T-DM1 3.6 mg/kg every 3 weeks (q3w) has demonstrated clinical activity in 2 phase II studies (TDM4258g and TDM4374g) in patients with pretreated HER2−positive MBC. The efficacy and safety of T-DM1 vs trastuzumab + docetaxel was investigated in patients with no prior MBC treatment in the randomized phase II study TDM4450g/BO21976. Here we report the PK of T-DM1 from that study and compare these data with those from studies that enrolled pretreated patients.

Methods: In all 3 studies, PK parameters, including maximum concentration (Cmax), area under the concentration-time curve (AUC), terminal half-life (t½), steady-state volume of distribution (Vss), and clearance (CL) were estimated by noncompartmental analysis (NCA) for serum T-DM1, serum total trastuzumab (conjugated and unconjugated), and plasma DM1. The effects of baseline trastuzumab and HER2 extracellular domain (ECD) concentration on T-DM1 exposure were explored and the relationship between T-DM1 exposure and clinical response (objective response rate [ORR] and progression-free survival [PFS]) was modeled.

Results: T-DM1 PK from evaluable patients enrolled in 3 studies are shown in Table 1. No significant correlations were observed between efficacy (as measured by ORR) and T-DM1 exposure (AUC, Cmax) after administration of T-DM1 to pretreated patients; efficacy-exposure analyses (ORR and PFS) for previously untreated patients will be presented. Patients with measurable concentrations of trastuzumab at baseline had a greater AUC during cycle 1; however, this did not impact ORR. Baseline circulating HER2 ECD concentrations also had no effect on ORR for pretreated patients. The impact of baseline trastuzumab and HER2 ECD concentrations on ORR and PFS in previously untreated patients will be presented.

Taxanes and COX-2 inhibitors: from molecular pathways to clinical practice

The taxanes paclitaxel and docetaxel are widely used antineoplastic agents that have demonstrated significant clinical activity against a number of human tumor types. Taxanes promote microtubule polymerization and stabilization which inhibits mitosis and leads to apoptosis. Taxanes induce a number of other molecular pathways. One such example is their ability to promote transcription of the cyclo-oxygenase (COX)-2 gene and to stabilize the COX-2 messenger RNA transcript. This leads to increased production of prostaglandins, which have been implicated in tumorigenesis. Increased COX-2 activity has been associated with tumor growth, poor prognostic characteristics, and unfavorable clinical outcome; therefore, up-regulation of COX-2 might attenuate the anti-tumor effect of the taxanes. This provides the rationale for the use of COX-2 inhibitors in combination with taxanes, as this could theoretically improve the clinical efficacy of paclitaxel and docetaxel. Results from preclinical studies have generally shown enhanced anticancer activity from the addition of COX-2 inhibitors to taxane treatment. Data from Phase II clinical studies in patients with non-small cell lung cancer (NSCLC) have suggested a marginal improvement in response rate when celecoxib is added to taxane therapy when compared with historical trials in similar patient groups receiving taxane therapy. There may also be a role for COX-2 inhibitors in ameliorating some of the side effects of taxane treatment, such as fatigue, myalgia, and arthralgia. Randomized clinical trials would be needed to establish whether COX-2 inhibitors improve the therapeutic profile of docetaxel or paclitaxel in patients with solid tumors.

Neoadjuvant docetaxel followed by adjuvant doxorubicin and cyclophosphamide in patients with stage III breast cancer

BACKGROUND

To evaluate clinical and pathologic response to neoadjuvant docetaxel therapy in patients with stage III breast cancer.

PATIENTS AND METHODS

Forty-five patients were planned to receive four cycles of docetaxel 100 mg/m2 every 3 weeks, followed by surgery, four cycles of doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 (AC) every 3 weeks, radiation therapy (RT), and tamoxifen when indicated.

RESULTS

After four cycles of neoadjuvant docetaxel, the clinical response rate within the breast was 59% (95% CI 42% to 73%) and overall (breast and axilla) was 49% (95% CI 38% to 72%) in the intention-to-treat (ITT) population. At the time of surgery, 10% (n=4) of patients had a pathologic complete response (pCR) in the breast, 27% (n=11) had a pCR within the axillary lymph nodes, and 7% (n=3) had a pCR in the breast and axilla (95% CI 2% to 21%). An additional 5% (n=2) had minimal residual invasive tumor (<5 mm). The 5-year overall survival rate was 80%. The percentage of patients with grade 3/4 neutropenia was similar during docetaxel (93%) and AC (86%), while a greater percentage of patients had febrile neutropenia during docetaxel treatment (27%) compared with AC treatment (7%).

CONCLUSIONS

Neoadjuvant docetaxel followed by surgery, adjuvant AC, hormonal therapy where indicated, and RT is an active regimen for patients with stage III breast cancer.

Creatine supplementation delays onset of fatigue during repeated bouts of sprint running

In this study we have investigated the effect of creatine supplementation on performance of repeated sprint runs in well-trained young male handball players. The subjects participated in a test before supplementation (T1) and then received creatine (15 g/d) or placebo for five days before a second test was carried out (T2). Following T2, a low dose of creatine (2 g/d) or placebo was maintained for an additional nine days before the third test was performed (T3). The tests consisted of eight 40 m maximal sprint runs with a 25-s rest period between each sprint. Run time was reduced on the last three sprint runs after five days with high doses of creatine supplementation compared to T1 (P < 0.05). Although the run time during the last three sprints was still significantly lower after supplementation of low doses of creatine compared to T1, analysis of variance showed only a tendency for an interaction between test day and random group (P = 0.14). No improvement was seen in the placebo group. Blood lactate was similar at T1 and T2 in the creatine and placebo groups. In conclusion, high doses of creatine supplementation improve performance during repeated sprint runs in well-trained handball players. Further studies are needed to clarify whether low doses of creatine supplementation, after a period with supplementation of high doses, are able to maintain improved performance.

Glutamic acid 203 of the cAMP-dependent protein kinase catalytic subunit participates in the inhibition by two isoforms of the protein kinase inhibitor

Although the protein kinase inhibitors (PKIs) are known to be potent and specific inhibitors of the catalytic (C) subunit of cAMP-dependent protein kinase, little is known about their physiological roles. Glutamate 203 of the C alpha isoform (C alpha E203) has been implicated in the binding of the arginine 15 residue of the skeletal isoform of PKI (PKI alpha R15) (Knighton, D. R., Zheng, J., Ten Eyck, L. F., Xuong, N., Taylor, S.S., and Sowadski, J. M. (1991) Science 253, 414-420). To investigate the role of C alpha E203 in the binding of PKI and in vivo C-PKI interactions, in vitro mutagenesis was used to change the C alpha E203 codon of the murine C alpha cDNA to alanine and glutamine codons. Initially, the C alpha E203 mutant proteins were expressed and purified from Escherichia coli. C alpha E203 is not essential for catalysis as all of the C subunit mutants were enzymatically active. The mutation of Glu203 did increase the apparent Km for Leu-Arg-Arg-Ala-Ser-Leu-Gly (Kemptide) severalfold but did not affect the apparent Km for ATP. The Vmax(app) was not affected by the mutation of C alpha E203. The mutation of C alpha E203 compromised the ability of PKI alpha (5-24), PKI alpha, and PKI beta to inhibit phosphotransferase activity. PKI alpha was altered using in vitro mutagenesis to probe the role of Arg15 in interacting with C alpha E203. The PKI alpha R15A mutant was reduced in its inhibition of C alpha. Preliminary studies of the expression of these C alpha mutants in COS cells gave similar results. These results suggest that the C alpha E203 mutants may be useful in assessing the role of PKI in vivo.

Inhibition of protein kinase-A by overexpression of the cloned human protein kinase inhibitor

Human cDNA clones for a heat-stable protein kinase inhibitor (PKI) protein of the cAMP-dependent protein kinase (PKA) were isolated using a mouse PKI cDNA fragment. Two human cDNA clones of 1.7 and 2.0 kb were sequenced and shown to encode the entire open reading frame of 228 nucleotides. Together these clones comprised 2147 nucleotides of the mRNA. The deduced amino acid sequence of the human clones showed 100% identity to the rabbit skeletal muscle PKI protein and 97% identity to the mouse brain PKI. The mouse and human PKI cDNAs shared nucleotide homology in their 3' untranslated regions as well as in the 32 nucleotides immediately 5' of the translation initiation site. Northern blot analysis of human skeletal muscle RNA with a human cRNA probe detected a major mRNA of approximately 4.0 kb. Transient overexpression in COS cells verified that a heat-stable inhibitor of protein kinase was produced by he human PKI cDNA, and protein extracts from the transfected COS cells inhibited both the C alpha and C beta isoforms of the PKA catalytic subunit with equal efficacy. Functional expression of the human PKI protein was further studied by assaying the ability of PKI expression vectors to inhibit PKA catalytic subunit stimulation of transcription from the human enkephalin promoter. In these studies, elimination of a conserved alternative translation start site in the 5' untranslated region of PKI was shown to potentiate the inhibitory activity of the PKI expression vector.

Isolation and characterization of cDNA clones for an inhibitor protein of cAMP-dependent protein kinase

Synthetic oligonucleotides were designed to amplify DNA sequences related to the heat-stable protein kinase inhibitor (PKI) isolated from rabbit skeletal muscle. Using these oligonucleotides, a 167-base pair fragment was isolated and shown to code for a portion of the mouse protein kinase inhibitor gene. This amplified DNA sequence was used to isolate three cDNA clones from a mouse brain cDNA library. A composite sequence was derived from these clones and contained a 228-nucleotide open reading frame encoding a protein of 76 amino acids. In addition, the sequence contained 29 nucleotides of 5'-untranslated and 2022 nucleotides of 3'-untranslated regions of the mouse PKI mRNA. Northern blot analysis of various mouse tissues indicated that the 3.8-kilobase pair mRNA is present at high levels in skeletal muscle and brain but is present at lower levels in heart, testis, and liver. RNase protection experiments also suggested that skeletal muscle and brain represent tissues of highest expression and that similar nucleotide sequences are found in the skeletal muscle, brain, and testicular transcripts. Southern blot analysis indicated a single prominent species of genomic DNA sequence related to the mouse PKI cDNA clones but a minor species was also detected.

Affinity purification of the C alpha and C beta isoforms of the catalytic subunit of cAMP-dependent protein kinase

A synthetic peptide of 18 amino acids corresponding to the inhibitory domain of the heat-stable protein kinase inhibitor was synthesized and shown to inhibit both the C alpha and C beta isoforms of the catalytic (C) subunit of cAMP-dependent protein kinase. Extracts from cells transfected with expression vectors coding for the C alpha or the C beta isoform of the C subunit required 200 nM protein kinase inhibitor peptide for half-maximal inhibition of kinase activity in extracts from these cells. An affinity column was constructed using this synthetic peptide, and the column was incubated with protein extracts from cells overexpressing C alpha or C beta. Elution of the affinity column with arginine allowed single step isolation of purified C alpha and C beta subunits. The C alpha and C beta proteins were enriched 200-400-fold from cellular extracts by this single step of affinity chromatography. No residual inhibitory peptide activity could be detected in the purified protein. The purified C subunit isoforms were used to demonstrate preferential antibody reactivity with the C alpha isoform by Western blot analysis. Furthermore, preliminary characterization showed both isoforms have similar apparent Km values for ATP (4 microM) and for Kemptide (5.6 microM). These results demonstrate that a combination of affinity chromatography employing peptides derived from the heat-stable protein kinase inhibitor protein and the use of cells overexpressing C subunit related proteins may be an effective means for purification and characterization of the C subunit isoforms. Furthermore, this method of purification may be applicable to other kinases which are known to be specifically inhibited by small peptides.