2015年3月10日讯 /生物谷BIOON/--十五个月以前，百特医疗和CTI生物公司（现为Cell Therapeutics）签订了一份协议，合作开发治疗骨髓纤维化药物pacritinib。协议规定，百特公司将向Cell Therapeutics支付6000万美元的预付款和高达1亿1千2百万美元的里程碑奖金。
这一协议对当时刚刚被FDA拒之门外的Cell Therapeutics公司来说无疑是雪中送炭。如今，两家公司终于宣布这一药物临床三期研究取得积极进展。临床三期研究显示，pacritinib治疗组患者的脾脏体积出现显著缩小。而此次临床三期研究的首要终点为pacritinib治疗组的脾脏体积缩小程度比对照JAK2抑制物治疗组脾脏体积缩小程度多达35%以上。
此外，研究还显示，有50名患者对输血治疗的依赖性下降。在安全性方面，此次临床三期研究结果的数据与此前的临床二期研究一致，有三名患者因副作用而停止用药，五名患者因出现腹泻而降低用药剂量。
研究人员介绍称，虽然目前JAK2抑制物类疗法能够有效治疗骨髓纤维化，但是一些患者在接受这类药物治疗时会出现血小板减少的副作用。而pacritinib则有望能够填补临床这一空白。
两家公司并未透露详细的临床三期数据，仅表示将稍后举行一个相关学术研讨会来公布实验数据细节。但首次积极结果的影响，Cell Therapeutics的股价上扬17%之多。不过，这并不意味着pacritinib的上市之路就此高枕无忧。
鉴于Cell Therapeutics公司开发pixantrone的坎坷经历，更多的分析人士则表现出审慎的态度。此前公司推出的另一种抗肿瘤药物Pixuvri (pixantrone)的上市之路也是波折重重。
虽然欧盟最终以有条件批准的方式批准这一药物上市，但Pixuvri的表现并不乐观，2014年前九个月的销售额仅为400万美元。因此，pacritinib是否能为百特公司和Cell Therapeutics带来惊喜尚未可知。
详细英文报道：
Some 15 months after Baxter ($BAX) signed on with CTI BioPharma--then called Cell Therapeutics--on a late-stage therapy for myelofibrosis called pacritinib, the partners say they have come up with statistically significant topline data on its effectiveness and safety. But after the biotech's many twists and turns taken trying to advance pixantrone over the years, a few longtime observers preferred to wait and see the actual numbers before deciding for themselves.
CTI ($CTIC) got $60 million upfront and a promise of $112 million in development milestones from Baxter back in the fall of 2013 for their partnership, gaining some badly needed credibility for itself after the FDA scorned pixantrone and the biotech's failed attempt to win an approval for lymphoma. This morning investigators say that their blood cancer drug produced a statistically significant response in reduction of spleen volume, even regardless of low initial platelet counts, but said the details will be held back for a scientific conference. The primary endpoint was a reduction of 35% or more in spleen volume compared with best available therapy--aside from JAK2 inhibitors.
There was also a reduction in transfusion dependence in a group of 50 patients. On the safety front three patients stopped therapy and 9 more had to have their doses reduced due to diarrhea, though the researchers say that the safety profile looked "consistent" with Phase II.
CTI's shot jumped about 17% on the news in premarket trading, evidence of the skepticism that the biotech generates.
"Despite the introduction of JAK2 inhibitors as effective therapies for patients with myelofibrosis, there remains a treatment gap for patients with disease-related or treatment emergent thrombocytopenia. The currently approved drug may require dose titration to less effective doses in this patient population, thus limiting our ability to effectively treat them. Results from the PERSIST-1 randomized trial demonstrate that pacritinib could address this unmet medical need," said Claire Harrison, one of the principal investigators for PERSIST-1.
There is some historical data on pacritinib. In S*Bio's Phase II with 34 patients 24% of patients had a reduction in spleen volume of 35% or more.
Its history suggests CTI faces a painstaking review by regulators before it can expect to get to the market with this drug.
In early 2010, regulators and experts scathingly objected to CTI's (Cell Therapeutics') development process and application for Pixuvri (pixantrone), bluntly objecting to the data as inadequate for an approval. Cell Therapeutics found itself opposed by Richard Pazdur, the powerful oncology drug-review chief at the agency. And later the biotech sparked considerable controversy when it unexpectedly yanked its new application for the treatment after claiming it needed more time to prep for an advisory committee review. The EU provided a conditional approval for Pixuvri, though, which generated a little more than $4 million in net product sales in the first 9 months of 2014.