The American Society of Hematology (ASH) annual meeting is one of the most important medical conferences held each year, focusing on new drugs to treat blood-related diseases, including blood cancers.

Naturally, the ASH meeting, which starts on Dec. 2, grabs the attention of healthcare investors.

On Thursday, research abstracts previewing clinical data to be presented at the ASH meeting were posted online. Some of the abstracts contain new clinical data, which has investors buzzing and drug stocks moving -- mostly down in early trading. 

Here's a rundown of noteworthy ASH abstracts from Thursday release:

Bluebird Bio (BLUE) - Get bluebird bio, Inc. Report :

In beta thalassemia, five patients with the non beta zero/beta zero subtype treated with Bluebird's gene therapy Lentiglobin and followed for at least 12 months remain free of blood transfusions. Another five beta thalassemia patients with the beta zero/beta zero subtype, again treated with Lentiglobin gene therapy and followed for at least 12 months, are showing a median 60% reduction in blood transfusion requirements.

In sickle cell disease, one "super responding" patient continues to remain symptom free 18 months after receiving Lentiglobin. Another seven treated sickle cell patients, however, are not responding as well, echoing subpar results first disclosed last year. Changes made to Lentiglobin to boost its potency, announced last month, are intended to improve the response rate in sickle cell patients.

The relevant Bluebird ASH abstracts can be found here, here and here.

Spark Therapeutics (ONCE) - Get Spark Therapeutics, Inc. Report :

The first seven hemophilia B patients, treated with SPK-9001 gene therapy, have not required infusions of factor IX to prevent bleeding. Four of the seven patients, followed longer than 12 weeks, showed a sustained, average factor IX level greater than 30% of normal. However, one patient showed an immune response to SPK-9001 resulting in a drop in factor IX activity level.

The Spark abstract can be found here.

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UniqureQURE is developing a competing hemophilia B gene therapy, AMT-060. It's ASH abstract can be seen here.

Trillium Therapeutics (TRIL) - Get Trillium Therapeutics Inc. Report :

A new safety concern related to Trillium's lead cancer drug TTI-621 was disclosed for the first time in Thursday's ASH abstract. The company is now looking at a lower dose of the drug.

The 0.3 mg/kg dose was associated with reversible, dose-limiting toxicity (DLT) in 2 of 5 pts: one pt with G3 elevated ALT/AST and G4 platelet count, and a second pt with G4 platelet count who was transfused. Dosing at 0.2 mg/kg is now being explored.

The abstract can be found here.

Global Blood Therapeutics (GBT) - Get Global Blood Therapeutics Inc Report :

Today's ASH abstracts re-hashed previously presented data on Global Blood's sickle cell disease drug GBT-440. There will be new data presented at the meeting in December.

Achillion Pharmaceuticals (ACHN) - Get Achillion Pharmaceuticals, Inc. Report :

A potential safety concern related to the company's complement factor D drug ACH-4471 was disclosed Thursday in a press release (not in an ASH abstract.)

To date in the MAD study, ACH-4471 has been generally well tolerated across three dose cohorts (200 mg, 500 mg or 800 mg given every 12 hours) with no treatment-related SAEs reported. Two cases of self-limited, ALT elevations (Grade 3 and 4) were observed post-treatment in the mid- and high dose groups, respectively, with neither subject exhibiting signs or symptoms of hepatic decompensation. Both subjects' ALT levels normalized without intervention during follow up. Further, no treatment-associated fever or infections were observed.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.