Switching to the AFFINITY-2 study (Study 175) in type 2 diabetics, Afrezza's A1c reduction of 0.82% was superior to placebo's A1c reduction of 0.42%. (All patients were also treated with oral diabetes medications.)

The between-group difference in A1c of 0.4%, while statistically significant, was lower than the 0.5 to 1.0% difference MannKind hoped to achieve in this study. Again, MannKind has every right to declare the study positive because it met the primary endpoint, but Afrezza's performance still underwhelmed.

Afrezza also caused more weight gain among type 2 diabetics and the difference in fasting blood glucose between Afrezza and placebo was not statistically significant.

All in, Afrezza is mediocre insulin, with lots of data, particularly around lung function, still undisclosed. I give MannKind 50-50 odds, at best, for an FDA approval this time around. (FDA has already rejected Afrezza twice.) Even if approved, Afrezza is far from the blockbuster product MannKind supporters believe it is, making MannKind a very over-valued stock today.

Next up, Vical ( VICL).

Steven B. emails:

Nice call on VICL. Your views on the prospects for the Allovectin trial convinced me to sell and saved me some money. I don't always agree but I certainly always consider and respect your position. Investors should do themselves a favor and stop taking opposing opinions personally and use them to test the strength of their own thesis. Thanks and all the best.

Thanks, Steven. And I agree with you about the importance of testing your investment thesis -- bullish or bearish -- against the opposite argument. Unfortunately, there will always be investors like Ken Luskin of Intrinsic Value Asset Management who, to their clients' detriment, only view the other side as the enemy.

Note the dates on Luskin's tweets. Here's what happened to Vical soon after: VICL Chart VICL data by YCharts

Next up, Osiris Therapeutics ( OSIR):

No, Jason, you're not alone. Alexey Bersenev, who tweets under the handle @cell_nnm, collected negative (smartly so) Twitter reactions to the Grafix diabetic foot ulcer data.

On his blog, Bersenev also questions Osiris' claim that Grafix is a true stem-cell product:

To me, there is no any piece of evidence that Grafix indeed "stem cell product." Based on what Osiris is making a claim about it? Based on presence of MSC in the product? Well, let me tell you this - every piece of tissue mashed in a dish will contain some sort of stem cells and more likely they will be MSC or alike. Is it a valid reason to qualify product as "stem cell product"? NO! A drop of blood contains stem cells, but blood transfusion products are not "stem cell products." Donor organs for transplantation contain stem cells, but they are not "stem cell products."

Reality check on Osiris: CEO Randy Mills is making some ludicrous claims about Grafix and its wound-healing ability.

Grafix is not an FDA-approved drug or medical device. Grafix is a bandage embedded with unmodified and uncultured cellular tissue derived from human placentas and other growth factors. As such, Grafix is considered by FDA to be a human cells, tissue and cellular and tissue-based product, or HCT/P, which means it can be sold without regulatory review as a drug or medical device.

Grafix competes against many other, similar HCT/P products in the diabetic foot ulcer/wound-healing market. MiMedx Group's ( MDXG) EpiFix is just one example. The most commercially successful wound-healing products -- Shire's ( SHHPY) DermaGraft and Organogenesis' Apligraf -- are actually classified as medical devices because they underwent formal FDA regulatory review.

Osiris' diabetic foot ulcer study compared Grafix to a plain bandage so the company cannot make any comparisons of Grafix to competing wound care products. In fact, all of these products are essentially the same and have similar wound-healing properties.

Osiris' Mills says Grafix is the best wound-healing product but this is just stock-promoting marketing blather. He has no data to back up his boast. In typical Osiris fashion, important details about the Grafix study, including baseline characteristics of the patients, wound recurrence and persistence of response data, have not been disclosed. The study has not been published or presented at a medical meeting yet. Osiris has a bad habit of using press releases to promulgate half-truths about clinical trial results, so there's no reason to believe last week's Grafix data announcement is any more transparent.

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