Unfortunately, the potential problems with IGF would seem to negate any of these theoretical benefits.  It has been shown that improper use of hormones such as dehydroepiandrosterone (DHEA), androstenedione, and human growth hormone may increase the risk for development of prostate cancer or promote the growth of existing prostate cancer by raising IGF-1 levels.  Therefore, men who are taking supplements with IGF in it (or those that raise IGF levels) could theoretically be putting themselves at an increased risk for prostate cancer.  Again, it hasn’t been rigorously studied so it’s impossible to know for sure, but if you have any risk factors for prostate cancer, it’s probably best to avoid taking this supplement.  
Studies have found that deer antlers themselves contain a highly concentrated amount of essential trace minerals, fatty acids, amino acids and growth factors that can all support the immune system. This includes the gastrointestinal tract, where the majority of the immune system is found. Antlers contain minerals such as: calcium, phosphorus, magnesium, iron, potassium and sodium in addition to numerous minor components.
Data is limited. Two studies (n=40 and 168) investigating the efficacy of elk velvet antler supplementation on rheumatoid arthritis found no effect, while a study conducted in people with osteoarthritis (n=53) reported symptomatic relief among participants. The small sample sizes may result in the trials being underpowered to detect effects.25, 28, 29
A systemic review on human interventions[25] makes note of a study conducted on patients of osteoarthritis (Edelman et al. 2000; cannot be located online) which found improvements in joint pain symptoms relative to baseline in the Velvet Antler group and not placebo, although a lack of information on blinding and randomization precludes results that can be drawn from this study.