Schalm Stefanie S, O'Hearn Erin, Wilson Kevin, LaBranche Timothy P, Silva Grace, Zhang Zhuo, DiPietro Lucian, Bifulco Neil, Woessner Richard, Stransky Nicolas, Sappal Darshan, Campbell Robert, Lobbardi Riadh, Palmer Michael, Kim Joseph, Ye Chaoyang, Dorsch Marion, Lengauer Christoph, Guzi Timothy, Kadambi Vivek, Garner Andrew, Hoeflich Klaus P
Blueprint Medicines Corporation, Cambridge, Massachusetts.
Gastro Hep Adv. 2022 Nov 8;2(3):307-321. doi: 10.1016/j.gastha.2022.11.004. eCollection 2023.
Fibrolamellar carcinoma (FLC) is a rare, difficult-to-treat liver cancer primarily affecting pediatric and adolescent patients, and for which precision medicine approaches have historically not been possible. The gene fusion was identified as a driver of FLC pathogenesis. We aimed to assess whether FLC tumors maintain dependency on this gene fusion and determine if PRKACA is a viable therapeutic target.
FLC patient-derived xenograft (PDX) shRNA cell lines were implanted subcutaneously into female NOD-SCID mice and tumors were allowed to develop prior to randomization to doxycycline (to induce knockdown) or control groups. Tumor development was assessed every 2 days. To assess the effect of treatment with novel selective PRKACA small molecule kinase inhibitors, BLU0588 and BLU2864, FLC PDX tumor cells were implanted subcutaneously into NOD-SCID mice and tumors allowed to develop. Mice were randomized to treatment (BLU0588 and BLU2864, orally, once daily) or control groups and tumor size determined as previously.
Knockdown of DNAJB1-PRKACA reversed a FLC-specific gene signature and reduced PDX tumor growth in mice compared to the control group. Furthermore, FLC PDX tumor growth was significantly reduced with BLU0588 and BLU2864 treatment vs control ( = .003 and = .0005, respectively).
We demonstrated, using an inducible knockdown and small molecule approaches, that FLC PDX tumors were dependent upon DNAJB1-PRKACA fusion activity. In addition, this study serves as a proof-of-concept that PRKACA is a viable therapeutic target for FLC and warrants further investigation.
纤维板层癌（FLC）是一种罕见的、难以治疗的肝癌，主要影响儿童和青少年患者，而且以往一直无法采用精准医学方法进行治疗。该基因融合被确定为FLC发病机制的驱动因素。我们旨在评估FLC肿瘤是否维持对这种基因融合的依赖性，并确定PRKACA是否为一个可行的治疗靶点。
将源自FLC患者的异种移植（PDX）shRNA细胞系皮下植入雌性NOD-SCID小鼠体内，待肿瘤形成后再随机分为强力霉素组（诱导基因敲低）或对照组。每2天评估一次肿瘤生长情况。为评估新型选择性PRKACA小分子激酶抑制剂BLU0588和BLU2864的治疗效果，将FLC PDX肿瘤细胞皮下植入NOD-SCID小鼠体内，待肿瘤形成。将小鼠随机分为治疗组（BLU0588和BLU2864，口服，每日一次）或对照组，并如前所述测定肿瘤大小。
与对照组相比，DNAJB1-PRKACA基因敲低逆转了FLC特异性基因特征，并降低了小鼠PDX肿瘤的生长。此外，与对照组相比，BLU0588和BLU2864治疗显著降低了FLC PDX肿瘤的生长（分别为P = 0.003和P = 0.0005）。
我们通过诱导性基因敲低和小分子方法证明，FLC PDX肿瘤依赖于DNAJB1-PRKACA融合活性。此外，本研究证明PRKACA是FLC一个可行的治疗靶点，值得进一步研究。
