Use of Advanced Flexible Modeling Approaches for Survival Extrapolation from Early Follow-up Data in two Nivolumab Trials in Advanced NSCLC with Extended Follow-up

OBJECTIVES

Immuno-oncology (IO) therapies are often associated with delayed responses that are deep and durable, manifesting as long-term survival benefits in patients with metastatic cancer. Complex hazard functions arising from IO treatments may limit the accuracy of extrapolations from standard parametric models (SPMs). We evaluated the ability of flexible parametric models (FPMs) to improve survival extrapolations using data from 2 trials involving patients with non-small-cell lung cancer (NSCLC).

METHODS

Our analyses used consecutive database locks (DBLs) at 2-, 3-, and 5-y minimum follow-up from trials evaluating nivolumab versus docetaxel in patients with pretreated metastatic squamous (CheckMate-017) and nonsquamous (CheckMate-057) NSCLC. For each DBL, SPMs, as well as 3 FPMs-landmark response models (LRMs), mixture cure models (MCMs), and Bayesian multiparameter evidence synthesis (B-MPES)-were estimated on nivolumab overall survival (OS). The performance of each parametric model was assessed by comparing milestone restricted mean survival times (RMSTs) and survival probabilities with results obtained from externally validated SPMs.

RESULTS

For the 2- and 3-y DBLs of both trials, all models tended to underestimate 5-y OS. Predictions from nonvalidated SPMs fitted to the 2-y DBLs were highly unreliable, whereas extrapolations from FPMs were much more consistent between models fitted to successive DBLs. For CheckMate-017, in which an apparent survival plateau emerges in the 3-y DBL, MCMs fitted to this DBL estimated 5-y OS most accurately (11.6% v. 12.3% observed), and long-term predictions were similar to those from the 5-y validated SPM (20-y RMST: 30.2 v. 30.5 mo). For CheckMate-057, where there is no clear evidence of a survival plateau in the early DBLs, only B-MPES was able to accurately predict 5-y OS (14.1% v. 14.0% observed [3-y DBL]).

CONCLUSIONS

We demonstrate that the use of FPMs for modeling OS in NSCLC patients from early follow-up data can yield accurate estimates for RMST observed with longer follow-up and provide similar long-term extrapolations to externally validated SPMs based on later data cuts. B-MPES generated reasonable predictions even when fitted to the 2-y DBLs of the studies, whereas MCMs were more reliant on longer-term data to estimate a plateau and therefore performed better from 3 y. Generally, LRM extrapolations were less reliable than those from alternative FPMs and validated SPMs but remained superior to nonvalidated SPMs. Our work demonstrates the potential benefits of using advanced parametric models that incorporate external data sources, such as B-MPES and MCMs, to allow for accurate evaluation of treatment clinical and cost-effectiveness from trial data with limited follow-up.

HIGHLIGHTS

Flexible advanced parametric modeling methods can provide improved survival extrapolations for immuno-oncology cost-effectiveness in health technology assessments from early clinical trial data that better anticipate extended follow-up.Advantages include leveraging additional observable trial data, the systematic integration of external data, and more detailed modeling of underlying processes.Bayesian multiparameter evidence synthesis performed particularly well, with well-matched external data.Mixture cure models also performed well but may require relatively longer follow-up to identify an emergent plateau, depending on the specific setting.Landmark response models offered marginal benefits in this scenario and may require greater numbers in each response group and/or increased follow-up to support improved extrapolation within each subgroup.

Wound healing complications following folded flap palatoplasty in brachycephalic dogs

OBJECTIVE

To determine the incidence and characteristics of wound healing complications after folded flap palatoplasty (FFP).

METHODS

Prospective study of 25 dogs that underwent FFP as a component of corrective multilevel surgery for brachycephalic obstructive airway syndrome. Oropharyngeal re-examination was conducted after a minimum of 28 days post-operatively, unless indicated earlier by the onset of clinical signs.

RESULTS

Wound healing complications occurred in nine dogs (36%). Minor and major wound complications were diagnosed at a median of 36 days (1.5-51 days) post-operatively. Eight dogs had major wound complications, four of which showed no associated clinical signs. Two patterns of major wound complications were observed: incisional dehiscence (ID) with caudal retraction of the soft palate mucosa and development of a full-thickness defect (FTD) in the centre of the soft palate. Revision of the soft palate surgery was performed in five dogs, failing again in one dog with ID. Clinical signs resolved in symptomatic dogs after revision surgery to close FTD.

CONCLUSION

In this study, wound healing complications were common after FFP and were not associated with significant clinical deterioration. Further research is necessary to determine the value and timing of routine post-operative oropharyngeal examination for assessment of soft palate healing after FFP as well as the indication for and success of approaches to the management of wound healing complications. The two distinct patterns of FFP failure recognised may provide insight into the underlying causes and lead to refinements in folded flap palatoplasty technique.

Profiles of medicinal cannabis patients attending compassion centers in rhode island

Little is understood regarding medicinal marijuana dispensary users. We sought to characterize socio-demographics and reasons for medicinal marijuana use among medical cannabis dispensary patients in Rhode Island. Participants (n=200) were recruited from one of two Compassion Centers in Rhode Island and asked to participate in a short survey, which included assessment of pain interference using the Brief Pain Inventory (BPI). The majority of participants were male (73%), Caucasian (80%), college educated (68%), and had health insurance (89%). The most common reason for medicinal marijuana use was determined to be chronic pain management. Participants were more likely to have BPI pain interference scores of > 5 if they were older (OR: 1.36, 95% CI: 1.04-1.78) or reported using cannabis as a substitute for prescription medications (OR: 2.47, 95% CI: 1.23-4.95), and were less likely to have interference scores of >5 if they had higher income levels (OR: 0.53, 95% CI: 0.40-0.70) or reported having ever received treatment for an alcohol use disorder. One-fifth of participants had a history of a drug or alcohol use disorder. Most participants report that medicinal cannabis improves their pain symptomology, and are interested in alternative treatment options to opioid-based treatment regimens.

Addressing the increasing burden of sexually transmitted infections in Rhode Island

The rates of sexually transmitted infections (STI) including chlamydia, gonorrhea, and syphilis, are increasing across the United States, including in Rhode Island (RI). These STIs affect many otherwise healthy adolescents and young adults, and represent a significant source of morbidity. The Centers for Disease Control and Prevention encourages states to develop strategies for addressing increasing STI rates in the setting of diminishing public health resources. The RI Department of Health (DOH) works with providers and funded community- based organizations to promote STI screening, expedited partner therapy, and partner services to reduce STI rates. The Miriam Hospital Immunology Center opened a public HIV/STI Clinic, which offers free and confidential testing for HIV, viral hepatitis, chlamydia, gonorrhea, and syphilis, as well as post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) services to prevent HIV. In collaboration with the RI DOH, the Clinic serves as a referral source across the state for complicated STI cases.

Investigation and clinical application of a novel axial pattern flap for nasal and facial reconstruction in the dog

OBJECTIVE

To describe the vascular supply to a facial skin flap based at the commissure of the lip in the dog and report on its use in four dogs.

STUDY DESIGN

Experimental and prospective clinical study. Animals Five canine cadavers and four client-owned dogs.

METHODS

In the cadavers, the ventral aspect of the zygomatic arch, the ventral margin of the caudal mandible and the wing of the atlas were marked as anatomical boundaries of a skin flap that was elevated from the subcutaneous tissues to the level of the medial canthus of the eye. Methylene blue dye and barium sulphate solution were independently infused through a common carotid (three dogs) or facial artery (two dogs) catheter. Distribution of dye throughout the harvested skin was assessed subjectively. After contrast infusion the flap was excised and radiographed. The technique was used to reconstruct large facial or nasal defects in four dogs after tumour or skin lesion excision.

RESULTS

Cadaver dissections and contrast studies clearly demonstrated three direct cutaneous arteries, the superior and inferior labial arteries and the angularis oris artery, arborising within the base of the flap. A separate direct cutaneous branch of the angularis oris artery was identified. An arterial plexus was identified within the distal flap, within which this artery communicates with the transverse facial artery and a cutaneous branch of the masseteric artery. Dye infusion caused discolouration of the elevated skin and vasculature within the flap. The flap survived in all clinical cases with marginal distal necrosis in one dog.

CONCLUSIONS

The complex facial flap described is perfused by three direct cutaneous arteries and functions reliably in clinical cases.

Role of L-type Ca(2+) channels in transmitter release from mammalian inner hair cells I. Gross sound-evoked potentials

Intracochlear perfusion and gross potential recording of sound-evoked neural and hair cell responses were used to study the site of action of the L-type Ca(2+) channel blocker nimodipine in the guinea pig inner ear. In agreement with previous work nimodipine (1-10 microM) caused changes in both the compound auditory nerve action potential (CAP) and the DC component of the hair cell receptor potential (summating potential, or SP) in normal cochleae. For 20-kHz stimulation, the effect of nimodipine on the CAP threshold was markedly greater than the effect on the threshold of the negative SP. This latter result was consistent with a dominant action of nimodipine at the final output stage of cochlear transduction: either the release of transmitter from inner hair cells (IHCs) or the postsynaptic spike generation process. In animals in which the outer hair cells (OHCs) had been destroyed by prior administration of kanamycin, nimodipine still caused a large change in the 20-kHz CAP threshold, but even less change was observed in the negative SP threshold than in normal cochleae. When any neural contamination of the SP recording in kanamycin-treated animals was removed by prior intracochlear perfusion with TTX, nimodipine caused no significant change in SP threshold. Some features of the data also suggest a separate involvement of nimodipine-sensitive channels in OHC function. Perfusion of the cochlea with solutions containing Ni(2+) (100 microM) caused no measurable change in either CAP or SP. These results are consistent with, but do not prove, the notion that L-type channels are directly involved in controlling transmitter release from the IHCs and that T-type Ca(2+) channels are not involved at any stage of cochlear transduction.

Coding of sound pressure level in the barn owl's auditory nerve

Rate-intensity functions, i.e., the relation between discharge rate and sound pressure level, were recorded from single auditory nerve fibers in the barn owl. Differences in sound pressure level between the owl's two ears are known to be an important cue in sound localization. One objective was therefore to quantify the discharge rates of auditory nerve fibers, as a basis for higher-order processing of sound pressure level. The second aim was to investigate the rate-intensity functions for cues to the underlying cochlear mechanisms, using a model developed in mammals. Rate-intensity functions at the most sensitive frequency mostly showed a well-defined breakpoint between an initial steep segment and a progressively flattening segment. This shape has, in mammals, been convincingly traced to a compressive nonlinearity in the cochlear mechanics, which in turn is a reflection of the cochlear amplifier enhancing low-level stimuli. The similarity of the rate-intensity functions of the barn owl is thus further evidence for a similar mechanism in birds. An interesting difference from mammalian data was that this compressive nonlinearity was not shared among fibers of similar characteristic frequency, suggesting a different mechanism with a more locally differentiated operation than in mammals. In all fibers, the steepest change in discharge rate with rising sound pressure level occurred within 10-20 dB of their respective thresholds. Because the range of neural thresholds at any one characteristic frequency is small in the owl, auditory nerve fibers were collectively most sensitive for changes in sound pressure level within approximately 30 dB of the best thresholds. Fibers most sensitive to high frequencies (>6-7 kHz) showed a smaller increase of rate above spontaneous discharge rate than did lower-frequency fibers.

Relationship between oversizing of self-expanding stents and late loss index in carotid stenting

Stenting of the internal carotid artery is facilitated by stenting across the carotid bifurcation and sizing the diameter of a self-expanding stent to the large common carotid segment. This usually results in marked oversizing of the self-expanding stent in the internal carotid segment. This study was done to determine the relationship between stent oversizing and late luminal loss index after stenting of the internal carotid artery. Between September 1995 and March 1997, there were 165 patients (189 vessels) who underwent successful carotid stenting with self-expanding stents. Fifty-nine patients (63 vessels) had six-month follow-up carotid angiograms and on-line quantitative angiographic analysis. The mean reference diameter of the internal carotid arteries was 4.93+/-1.31 mm. Nominal stent size was 5 mm in 4 patients, 6 mm in 6 patients, 8 mm in 106 patients, 10 mm in 77 patients, and 12 mm in 1 patient. The average stent/patient was 1.03+/-0.16. There were three patients who had more than 50% diameter renarrowing at follow-up. The mean late loss index was 0.25+/-0.41. By linear regression analysis, there was no clear linear relationship between stent oversizing and late loss index after stenting (correlation coefficient = -0.21, P = 0.09). When analysis of variance with linear contrast was used to analyze six groups of different stent/artery ratios (from 1.4 to > or = 2), late loss indexes are significantly lower in the groups of high stent/artery ratio than the groups of low stent/artery ratio (P = 0.01). The process of oversizing of self-expanding stents deployed in the internal carotid artery does not appear to be associated with late restenosis and high stent/artery ratio seems to be associated with low late loss index.

Intraduodenal vaccination of brushtail possums with bacille Calmette-Guérin enhances immune responses and protection against Mycobacterium bovis infection

SETTING

An effective oral bacille Calmette-Guérin (BCG) vaccine would have advantages for use in humans and as an oral bait vaccine for protecting wild-life against bovine tuberculosis.

OBJECTIVE

To compare the level of protection against tuberculosis in intraduodenally BCG-vaccinated possums with those vaccinated intragastrically in order to determine whether degradation of BCG in the stomach lowers vaccine efficacy.

DESIGN

Three groups of five possums were vaccinated with BCG by the intraduodenal, intragastric or subcutaneous routes, with a fourth group serving as unvaccinated controls. The animals were later challenged intratracheally with a low dose of virulent Mycobacterium bovis.

RESULTS

Possums vaccinated intraduodenally with BCG had significantly greater lymphocyte blastogenic responses to bovine purified protein derivative (PPD) and lower lung bacterial counts in comparison with intragastrically vaccinated animals. In comparison with unvaccinated animals, all of the BCG-vaccinated groups had significant protection against M. bovis infection as assessed by changes in body weight, lung weight and reduction in numbers of mycobacteria and granulomas in the spleen.

CONCLUSION

The enhanced immune responses and protection against bovine tuberculosis observed in the intraduodenally BCG-vaccinated possums indicated that if BCG vaccine is protected from degradation in the stomach its efficacy should improve.

Hippocampal lesions impair navigational learning in experienced homing pigeons

Adult experienced homing pigeons from Maryland were subjected to hippocampal lesion and then transferred to a new loft in Ohio to examine what effect such treatment may have on learning to navigate to a new home loft. When subsequently released from an unfamiliar site, the hippocampal lesioned birds were impaired in taking up a vanishing bearing toward their new Ohio loft. This deficit is interpreted as an impairment in hippocampal-lesioned birds learning a new navigational map. Together with a previous study, the results suggest that an intact hippocampus is necessary if young naive or adult experienced homing pigeons are to learn a navigational map.

Hippocampal lesions impair navigational learning in experienced homing pigeons

Adult experienced homing pigeons from Maryland were subjected to hippocampal lesion and then transferred to a new loft in Ohio to examine what effect such treatment may have on learning to navigate to a new home loft. When subsequently released from an unfamiliar site, the hippocampal lesioned birds were impaired in taking up a vanishing bearing toward their new Ohio loft. This deficit is interpreted as an impairment in hippocampal-lesioned birds learning a new navigational map. Together with a previous study, the results suggest that an intact hippocampus is necessary if young naive or adult experienced homing pigeons are to learn a navigational map.

Social isolation effects on the "behavioral despair" forced swimming test: effect of age and duration of testing

Social loss is considered to be one of the major precipitants of depression. Prior work with the Porsolt forced swimming test (FST) has failed to demonstrate increases in despair-like immobility as a result of prior social isolation in adult animals. In the present work, increased immobility was observed in young Swiss Webster mice that had been socially isolated for 24 h prior to a 15-minute FST. The effect was not apparent until after the first five minutes of testing. The increase in immobility as a result of social isolation was apparent in 17-21-day-old animals but not in 26-30-day-old ones. Control experiments indicated that the increase in immobility was not due to the slightly higher weight loss of the socially isolated animals. Administration of reserpine (0.25 mg/kg) induced a marginal increase in immobility in the youngest animals but decreased immobility at later ages. These data suggest that the mouse only exhibits a short period of time during early development where social isolation can promote despair-like immobility in the FST and suggest that analyses of depressive processes which result from social variables may be best studied during a limited age range in this species.