Identifying senescence and immune biomarkers predictive of benefit to combined CDK4 and checkpoint blockade inhibition in patients with dedifferentiated liposarcoma

对于局部晚期或转移性分化良好的患者，几乎没有可行的治疗方法。 去分化脂肪肉瘤(WD/DDLS)，这是一种罕见且经常被忽视的孤儿癌症。确实有 在美国，每年约有1000名患者被诊断为WD/DDLS，而这些癌症通常不会 对化疗有反应。最近对细胞周期蛋白依赖性激酶4/6(CDK4/6)抑制剂的试验，动机是 发现CDK4基因在90%的WD/DDLS中被扩增，表明这些药物稳定了曾经发生过的疾病 在治疗前一直在增长，并证明了临床上有意义的无进展中位生存期(PFS) 12周时为66%，但反应不常见。 为了提高应答率和改善PFS收益，我们建议联合使用CDK4/6抑制剂 具有针对免疫检查点PD1抗体的Palbociclib。检查点抑制物具有一定的活性 DDLS，导致约8%的患者出现部分反应。CDK4/6抑制剂已经被证明增加了 检查点抑制剂对乳腺癌患者和动物抗肿瘤免疫的促进作用 模特们。在反应性肿瘤中，CDK4/6抑制剂触发衰老，导致细胞分泌促炎物质 细胞因子和生长因子(称为衰老相关分泌表型，或SASP)，提示 这些药物可能会增强抗肿瘤免疫力。 为了确定可能从这种联合疗法中受益的患者，我们将研究 使用治疗前和治疗中患者在建议阶段的活检标本的反应性和抵抗性 2帕波西利联合抗PD1抗体INCMGA0012试验。这些研究将集中在 先前确定的CDK4/6抑制剂诱导WD/DDLS衰老所需的细胞标志物 (MDM2周转，钙粘蛋白18表达)；终末衰老标志物(Angplt4)，抗肿瘤免疫 反应；和基因表达。因此，我们的具体目标是：(1)评估CDK4的安全性和有效性 帕波西利联合INCMGA0012阻断PD1治疗30例 WD/DDLS(结果：总应答率、PFS和总存活率)；(2)检查衰老的作用， 联合治疗对终末衰老和结果SASP的影响及其与 免疫反应；和(3)表征免疫微环境(特别是CD8+T细胞和PDL1+ 肿瘤细胞)和肿瘤基因的表达(用免疫组织化学以及散体和单细胞进行评估 RNA测序)，并检测它们在联合治疗前和联合治疗期间的变化 与临床反应和预后的关系。 这项试验的成功完成可能会导致一种新的联合免疫疗法的引入 WD/DDLS的策略和确定预测性生物标记物，以选择最有可能在两者中受益的患者 肉瘤和其他恶性肿瘤。

Few viable treatments exist for patients with locally advanced or metastatic well-differentiated or dedifferentiated liposarcoma (WD/DDLS), which are rare and often neglected orphan cancers. There are approximately 1000 patients per year in the US diagnosed with WD/DDLS, and these cancers generally do not respond to chemotherapy. Recent trials of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, motivated by the finding that the CDK4 gene is amplified in >90% of WD/DDLS, show these agents stabilize disease that had been growing prior to treatment and demonstrated clinically meaningful median progression-free survival (PFS) of 66% at 12 weeks but responses were uncommon. To enhance response rates and improve PFS benefit, we propose to combine the CDK4/6 inhibitor palbociclib with an antibody against the immune checkpoint PD1. Checkpoint inhibitors have some activity in DDLS, leading to partial responses in about 8% of patients. CDK4/6 inhibitors have been shown to increase the efficacy of checkpoint inhibitors and to promote antitumor immunity in breast cancer patients and animal models. In responsive tumors, CDK4/6 inhibitors trigger senescence, causing cells to secrete proinflammatory cytokines and growth factors (termed the senescence-associated secretory phenotype, or SASP), suggesting that these agents may enhance antitumor immunity. To identify patients likely to benefit from this combination therapy, we will investigate mechanisms of response and resistance using pre- and on-treatment biopsy specimens from patients on the proposed phase 2 trial of palbociclib combined with the anti-PD1 antibody INCMGA0012. These studies will focus on the cellular markers previously determined to be required for CDK4/6 inhibitor-induced senescence in WD/DDLS (MDM2 turnover, cadherin 18 expression); markers of terminal senescence (Angplt4), antitumor immune responses; and gene expression. Thus, our Specific Aims are to: (1) Assess the safety and efficacy of CDK4 inhibition using palbociclib in combination with PD1 blockade using INCMGA0012 in 30 patients with WD/DDLS (outcomes: overall response rate, PFS, and overall survival); (2) Examine the roles of senescence, terminal senescence and resultant SASP in response to the combination therapy and, their relationship with immune response; and (3) Characterize the immune microenvironment (specifically CD8+ T cells and PDL1+ tumor cells) and tumor gene expression (assessed with immunohistochemistry and both bulk and single-cell RNA sequencing) prior to and during combined treatment of palbociclib and INCMGA0012, and examine their association with clinical response and outcome. Successful completion of this trial may lead to the introduction of a novel combination immunotherapy strategy for WD/DDLS and identify predictive biomarkers for selection of patients most likely to benefit in both sarcoma and other malignancies.