Jose M Garcia, Beverly M K Biller, Márta Korbonits, Vera Popovic, Anton Luger, Christian J Strasburger, Philippe Chanson, Ronald Swerdloff, Christina Wang, Rosa Rosanna Fleming, Fredric Cohen, Nicola Ammer, Gilbert Mueller, Nicky Kelepouris, Frank Strobl, Vlady Ostrow, and Kevin C J Yuen
The macimorelin test is approved for the diagnosis of adult growth hormone deficiency (AGHD) based on its efficacy vs the insulin tolerance test (ITT). Macimorelin has a significant advantage over ITT in avoiding hypoglycemia. Analyses were conducted to determine whether macimorelin performance is affected by age, BMI, or sex, and evaluate its performance vs ITT over a range of GH cutpoints.
Post hoc analyses of data from a previous randomized phase 3 study included participants aged 18–66 years with BMI <37 kg/m2 and high (Group A), intermediate (Group B), or low (Group C) likelihood for AGHD based on pituitary history, and matched controls (Group D).
Probability of AGHD was estimated using unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted logistic models. Area under the curve (AUC) of the estimated receiver operating characteristic (ROC) curve (range, 0–1; 1 = perfect) was compared for adjusted vs unadjusted models. Separate analyses evaluated agreement, sensitivity, and specificity for macimorelin and ITT using cutpoints of 2.8, 4.0, 5.1, and 6.5 ng/mL.
For participants in Group A (n = 41) and Group D (n = 29), unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted models had ROC AUCs (95% CIs) of 0.9924 (0.9807–1), 0.9924 (0.9807–1), 0.9916 (0.9786–1), and 0.9950 (0.9861–1), respectively.
Macimorelin performance was not meaningfully affected by age, BMI, or sex, indicating robustness for AGHD diagnosis. Of the 4 GH cutpoints evaluated, the cutpoint of 5.1 ng/mL provided maximal specificity (96%) and high sensitivity (92%) and was in good overall agreement with the ITT at the same cutpoint (87%).
Gudmundur Johannsson, Martin Bidlingmaier, Beverly M K Biller, Margaret Boguszewski, Felipe F Casanueva, Philippe Chanson, Peter E Clayton, Catherine S Choong, David Clemmons, Mehul Dattani, Jan Frystyk, Ken Ho, Andrew R Hoffman, Reiko Horikawa, Anders Juul, John J Kopchick, Xiaoping Luo, Sebastian Neggers, Irene Netchine, Daniel S Olsson, Sally Radovick, Ron Rosenfeld, Richard J Ross, Katharina Schilbach, Paulo Solberg, Christian Strasburger, Peter Trainer, Kevin C J Yuen, Kerstin Wickstrom, Jens O L Jorgensen, and on behalf of the Growth Hormone Research Society
The Growth Hormone Research Society (GRS) convened a Workshop in 2017 to evaluate clinical endpoints, surrogate endpoints and biomarkers during GH treatment of children and adults and in patients with acromegaly.
GRS invited 34 international experts including clinicians, basic scientists, a regulatory scientist and physicians from the pharmaceutical industry.
Current literature was reviewed and expert opinion was utilized to establish the state of the art and identify current gaps and unmet needs.
Following plenary presentations, breakout groups discussed questions framed by the planning committee. The attendees re-convened after each breakout session to share the group reports. A writing team compiled the breakout session reports into a document that was subsequently discussed and revised by participants. This was edited further and circulated for final review after the meeting. Participants from pharmaceutical companies were not part of the writing process.
The clinical endpoint in paediatric GH treatment is adult height with height velocity as a surrogate endpoint. Increased life expectancy is the ideal but unfeasible clinical endpoint of GH treatment in adult GH-deficient patients (GHDA) and in patients with acromegaly. The pragmatic clinical endpoints in GHDA include normalization of body composition and quality of life, whereas symptom relief and reversal of comorbidities are used in acromegaly. Serum IGF-I is widely used as a biomarker, even though it correlates weakly with clinical endpoints in GH treatment, whereas in acromegaly, normalization of IGF-I may be related to improvement in mortality. There is an unmet need for novel biomarkers that capture the pleiotropic actions of GH in relation to GH treatment and in patients with acromegaly.