DCC-2618

DCC-2618 is an orally administered kinase switch control inhibitor for the treatment of gastrointestinal stromal tumors (GIST), advanced systemic mastocytosis (ASM), gliomas, and other solid tumors driven by KIT kinase or PDGFRα kinase. Deciphera is focusing the development of DCC-2618 in patient subgroups where significant unmet medical need exists despite currently available therapies.

While approved kinase inhibitors control certain initiating and drug resistance-causing mutations in KIT and PDGFRα, the kinases that drive disease progression in most GIST patients, these approved drugs fail to inhibit all known mutations. DCC-2618 was specifically designed to improve the treatment of GIST patients by inhibiting the full spectrum of mutations in KIT and PDGFRα. DCC-2618 is a pan-KIT and pan-PDGFRα inhibitor that blocks initiating KIT mutations in exons 9, 11, 13, 14, 17, and 18, known to be present in GIST patients and the D816V exon 17 mutation known to be present in ASM patients. DCC-2618 inhibits PDGFRα mutations in exon 18, including the D842V mutation that drives a subset of GIST.

Development Status

Tumor Type Target Status Retained Rights
GIST – 4th Line pan-KIT and pan-PDGFRα Phase 3 Pivotal Trial – Planned Worldwide
GIST – 2nd Line pan-KIT and pan-PDGFRα Phase 3 Pivotal Trial – Planned Worldwide
GIST, ASM, gliomas pan-KIT and pan-PDGFRα Phase 1 Expansion – Ongoing Worldwide
Solid Tumors pan-KIT and pan-PDGFRα Phase 1 Expansion – Ongoing Worldwide

Rationale for DCC-2618 in GIST:

GISTs are the most common sarcoma of the gastrointestinal tract and present most often in the stomach or small intestine. According to the American Cancer Society, in 2015 approximately 5,000 patients were newly diagnosed with GIST in the United States. Estimates for 5-year survival range from 48% to 90% depending upon the stage of the disease at diagnosis.

Metastatic KIT-driven GIST is a disease characterized by many mutations in KIT, with over 90% of individual KIT-driven GIST patients harboring multiple mutations that drive progression of their disease. The complex heterogeneity of KIT mutations within individual tumors and individual patients is a major cause of resistance to existing therapies. DCC-2618 has been designed to broadly inhibit all clinically relevant KIT mutations.

In PDGFRα-driven GIST, there are no approved therapies. The primary PDGFRα mutations are mostly insensitive to imatinib and other drugs approved for GIST. As a result, there is no clinical data regarding the emergence of secondary drug resistance mutations. DCC-2618 has been designed as a PDGFRα switch control inhibitor, which compared to a traditional kinase inhibitor, reduces the likelihood of treatment-emergent mutations.

In June 2017, findings were reported from the dose escalation stage of a Phase 1 trial of DCC-2618 at the ASCO 2017 meeting in Chicago, IL. Data from this dose escalation stage from a total of 48 patients demonstrated DCC-2618 was well tolerated at all doses up to 400 mg daily with no discontinuations due to a lack of tolerability or toxicity. The majority (38) of those enrolled were patients with GIST who had received an average of 3.4 prior kinase inhibitor therapies. In GIST patients shown to harbor a broad range of KIT and PDGFRα mutations who received at least 100 mg of DCC-2618 daily, we observed a disease control rate (DCR) of 85% (23 of 27 patients) at 8 weeks, 78% (18 of 23 patients) at 12 weeks and 60% (9 of 15 patients) at 24 weeks. The DCRs described above are based on investigator assessment of tumor response in a limited number of patients and may not be predictive of or consistent with the results of later trials, however they compare favorably with published results for other kinase inhibitors in less advanced patients (see Figure 1 below).

Fig.1
First Line
Imatinib (n=147)
(Blanke et al. 2008)
Second Line
Sunitinib (n=243)
(Demetri et al. 2012)
Third Line
Regorafenib (n=133)
(Demetri et al. 2013)
TTP/PFS (months) 24.0 6.1 4.8
ORR (%) 68.1% 7.0% 4.5%
SD (%) 15.6% 53.0% 48.1%
Disease Control Rate 83.7%* 60.0%* 52.6%**
TTP Time To Progression PFS Progression Free Survival ORR Objective Response Rate SD Stable Disease

* Time point not disclosed   **At 12 weeks

Based on these results and the high level of unmet need, Deciphera plans to initiate Phase 3 clinical trials in fourth-line GIST and second-line GIST.

Rationale for DCC-2618 in Glioblastoma Multiforme (GBM):

Gliomas, including GBM, are among the most severe types of brain cancer. According to Central Brain Tumor Registry of the United States (CBTRUS), approximately 12,000 patients are projected to be diagnosed in 2016 with estimates for 1-year survival of around 40% and for 2-year survival of 15% to 20%. In approximately 15% of these patients, their disease is driven by chromosome 4 genetic amplifications that increases the activity of PDGFRα, KIT and closely related kinases.

In the dose escalation stage of the Phase 1 trial of DCC-2618, we observed a partial response in one GBM patient who had a 6-fold triple chromosome 4 amplification, and had progressed after three months of standard of care treatment. Based on this encouraging observation, Deciphera continues to evaluate the therapeutic potential of DCC-2618 in a Phase 1 expansion study that includes GBM patients.

Rationale for DCC-2618 in Advanced Systemic Mastocytosis (ASM):

Mastocytosis is a disease characterized by an abnormal accumulation of mast cells, a type of white blood cell, located in peripheral tissues and organs. Mast cells store components that mediate inflammatory and allergic responses. There are several subtypes of the disease, and outcomes can vary significantly by subtype.

Approximately 94% of SM patients are reported to have a somatic D816V mutation in KIT. This D816V mutation is a gain-of-function mutation in the KIT activation switch, which leads to unregulated KIT activation. The KIT receptor, which is widely expressed on mast cells, stimulates signaling pathways that control cell growth, differentiation and survival. The gain-of-function mutation, D816V, enables mast cells to proliferate in the absence of normal activation signals.

As a pan-KIT inhibitor, DCC-2618 potently inhibits the D816V mutation. We are enrolling ASM patients within an expansion cohort of our Phase 1 trial.