ALS全名肌萎缩性脊髓侧索硬化症，是一种发病率极低得罕见病。由于患者全身肌肉萎缩，而造成失去行动能力，严重时甚至肺部等器官功能也受到极大损伤。此前，风靡一时得冰桶挑战就是旨在为这类疾病募集善款。目前市面上治疗此类疾病的药物凤毛麟角。

今年早些时候，生物制药公司Cytokinetics公司公布了其治疗ALS药物tirasemtiv的中期临床研究数据。结果发现，这种药物未能达到其预定终点，即改善患者的行动能力，延缓ALS的发病进程。不过，研究人员分析后认为，tirasemtiv能够明显增大患者的慢肺活量（SVC）指标，即患者每次缓慢深呼吸能够吸入的最大气体量。SVC也被认为是评价ALS病情进程的一个重要指标。此次临床二期研究共有711名ALS患者参加。因此，Cytokinetic公司认为tirasemtiv仍然能够明显改善ALS患者的生存状况。目前，公司正着手准备相关数据以说服FDA批准公司进行关于tirasemtiv的临床三期研究。

然而，这一消息并未明显提振投资者的信心，tirasemtiv的中期研究临床数据刚刚公布时，Cytokinetic公司股价遭受重挫，此次利好消息也仅将股价提升6％，恢复至公司暴跌前的65％左右。显示出市场对tirasemtiv能够获得FDA青睐的疑虑。

最近一段时间，Cytokinetic公司的研发工作频频受挫。去年公司与安进公司开发的治疗心衰药物omecamtiv mecarbil临床二期研究也宣告失败，与此相关的研究数据也在进一步分析中。安进公司表示需要得到最终的分析结果后才会决定omecamtiv mecarbil的未来命运。

详细英文报道：

Earlier this year, Cytokinetics ($CYTK) tanked as its lead prospect, a treatment for amyotrophic lateral sclerosis (ALS), missed its primary endpoint and a slew of secondary goals in a mid-stage trial. But the drug did come through on one measure of lung function, and, upon analysis of the results, the biotech believes that could be its ticket to FDA approval.

The treatment, tirasemtiv, is designed to increase muscle sensitivity to calcium, thereby improving movement and functionality in patients with ALS and delaying the disease's characteristic fatigue. However, in a Phase IIb study dubbed BENEFIT-ALS, Cytokinetics' drug failed to significantly improve patient scores on a standardized measure of ALS symptoms, and it posted mixed results on its secondary goals.

But the 711-patient trial wasn't a total loss, the company said, as tirasemtiv charted a statistically significant benefit on patients' slow vital capacity (SVC), which is a measure of how much air they can exhale slowly after a deep breath. After running statistical analyses and consulting with neuromuscular experts, Cytokinetics is convinced improving SVC is a viable surrogate for improving ALS, and the company is now making that case to the FDA, hoping to kick off a late-stage trial on tirasemtiv next year.

"BENEFIT-ALS is the first clinical trial in patients with ALS to demonstrate a positive and potentially clinically meaningful effect on slow vital capacity, an important measure of disease progression and predictor of survival," CEO Robert Blum said in a statement. "We are encouraged by our initial interactions with the FDA relating to the results of BENEFIT-ALS and believe that our continuing discussions can inform our plans to pursue a potential registration program based on effects observed on respiratory function measured by slow vital capacity in patients with ALS."

Investors, however, would seem to be less than optimistic that the FDA will get behind the plan and sign off on SVC as a primary endpoint in Phase III. The latest news sent Cytokinetics' shares up about 6% on Monday, gains that hardly reverse the 65% dive the biotech took after first reporting its Phase IIb results.

Tirasemtiv's mid-stage misstep came on the heels of a setback for Cytokinetics' other lead program, the Amgen ($AMGN)-partnered heart failure treatment omecamtiv mecarbil. An intravenous formulation of the drug failed in Phase IIb, Amgen disclosed last year, and now the Big Biotech is waiting on data from a mid-stage study on an oral version before deciding whether to head into Phase III or scrap the program.