Troy Wilson
Analyst · STB Leerink. Your line is open
Thank you, Pete, and thank you all for joining us this afternoon. At Kura, we're committed to realizing the promise of precision medicines for the treatment of cancer. Approximately one year ago, on our year-end call, we talked of taking another step toward achieving that goal, following a successful end of Phase 2 meeting with FDA. Now a year later, I'm very pleased to report that our registration directed trial of tipifarnib in HRAS-mutant head and neck squamous cell carcinomas is under way. In addition to our efforts in HRAS-mutant solid tumors, we've also made considerable strides over the past year to broaden the potential to treat patients with tipifarnib. We demonstrated how to enrich for clinical activity in multiple indications, showed clinical proof-of-concept in angioimmunoblastic T-cell lymphoma or AITL, validated CXCL12 as a therapeutic target of tipifarnib in peripheral T-cell lymphoma or PTCL, and identified the potential association between CXCL12 expression and clinical benefit in pancreatic cancer. Together, these efforts are helping us to expand the opportunity for tipifarnib well beyond HRAS-mutant solid tumors. Now as we look forward to date in the year ahead, from each of our three ongoing Phase 2 clinical trials of tipifarnib, the execution of our registration directed trial remains our top priority. As a reminder, our registration-directed trial of tipifarnib in HRAS-mutant HNSCC has two cohorts; a non-interventional screening and outcomes cohort, which we call SEQ-HN, and a treatment cohort which we call AIM-HN. SEQ-HN is designed as a case control study to determine the treatment outcome of patients with recurrent or metastatic HNSCC with HRAS mutations. The primary objective of SEQ-HN is to determine the objective response rate of first-line therapy in patients with HNSCC that carry HRAS mutations compared to those without a known HRAS-mutation. In addition, the screening and outcomes cohort is expected to enable the identification of patients with HRAS mutations for potential enrollment into AIM-HN. AIM-HN is designed to enroll at least 59 patients with HRAS-mutant HNSCC who have received prior platinum-based therapy. The trial's primary endpoint is objective response rate. AIM-HN has approximately 80% power to detect a difference between a null hypothesis of 15%, which is the point estimate of the objective response rate of second-line therapy for recurrent and metastatic disease and 30% an objective response rate considered of interest. AIM-HN initiated in November of last year and is expected to take approximately two years to fully enroll. However, based upon the statistical assumptions, the trial could be positive as soon as 15 confirmed responses are observed, in order to reject the null hypothesis. Based on feedback from FDA, we believe that AIM-HN if positive, maybe adequate to support a new drug application seeking accelerated approval. We anticipate providing more information regarding the design of our registration directed trial at an upcoming medical meeting. Meanwhile, we continue to enroll HRAS-mutant HNSCC patients in our ongoing Phase 2 trial, which we call RUN-HN at clinical sites that have yet to open in AIM-HN. We plan to provide an update from RUN-HN in the second half of 2019, and we expect this update will include follow-up on ongoing patients in the trial, as well as preliminary data on newly enrolled patients in both our HNSCC and other SCC cohorts. Among the compelling features of the tipifarnib program, when we in-licensed it from Janssen where anecdotal reports of anti-tumor activity observed across various cancers, including lymphomas and leukemias, as well as certain solid tumors such as pancreatic and breast cancers. Given that these tumors do not typically carry HRAS mutations, we hypothesize there might be a molecular mechanism that would relate the observed anti-tumor activity to the inhibition of the farnesyltransferase enzyme in patients. Despite the fact that multiple large pharma companies worked on farnesyltransferase inhibitor programs for more than a decade, no such molecular mechanism had been described. Our previously reported preliminary results from our ongoing trial in PTCL, most recently at ASH in December 2018, showed a significant association between CXCL12 expression and clinical benefit. The data have also provided a clinical proof of concept in patients with AITL, an aggressive form of PTCL often characterized by high levels of CXCL12 expression. Of the 13 valuable AITL patients in the trial, two achieved a complete response and four achieved a partial response for an objective response rate of 46%. We also identified a particularly responsive patient subset in the Phase 2 trial. Specifically, patients with a high ratio of expression of CXCL12 to its receptor CXCR4, experienced a 50% objective response rate and a clinical benefit rate of 90% with tipifarnib. In other words, of the 10 patients in the trial, with a high ratio of CXCL12 to CXCR4 expression, only one patient progressed. This level of clinical activity was particularly noteworthy given that the patients were in the salvage setting, having experienced the median of three prior therapies. Results from an ancillary non-clinical study indicate that high CXCL12 is a negative prognostic factor for standard-of-care PTCL therapy. Our data suggests that as many as 40% of PTCL patients express high CXCL12. We believe the preliminary results reported at ASH, validate our observation that the CXCL12 pathway is a therapeutic target of tipifarnib and provide a potential path to pursue the development of tipifarnib using CXCL12 related biomarkers to enrich for patients most likely to benefit from treatment. We are encouraged by these lymphoma data in late-line patients and believe this represents another potential registrational opportunity. We anticipate providing an update on our ongoing Phase 2 trial, including duration of response data from the AITL cohort and additional data from the CXCL12 high PTCL cohort in mid-2019. We're also working to validate the utility of CXCL12 pathway biomarkers, as a strategy for patient enrichment in relapsed, refractory myeloid tumor indications. Enrollment in our ongoing Phase 2 trial in chronic myelomonocytic leukemia or CMML is stratified based upon levels of CXCL12 pathway biomarkers, and we've observed encouraging signs of clinical activity in patients with CMML. If confirmed, we believe this approach may allow us to extend the potential use of tipifarnib to other myeloid indications in settings, including previously untreated, poor risk in elderly patients with acute myeloid leukemia or AML. We anticipate presenting additional data from our CMML trial at a medical meeting later this year. The CXCL12 pathway plays critical roles mediating the growth and homing of lymphoid and myeloid cells. We are encouraged that our ongoing trials in PTCL and CMML, as well as our retrospective analysis of Janssens trials in AML and other diseases may allow us to pursue a biomarker guided approach to the development of tipifarnib across these and other CXCL12 expressing indications including diffuse large B-Cell Lymphoma, Hodgkin's lymphoma and Mycosis fungoides a form of cutaneous T-cell lymphoma in which evidence of activity an unselected populations has already been reported. Such a biomarker guided approach is currently being pursued successfully by others, against targets such as CD30 that are relevant across multiple Hematologic Malignancies. The progress we've made in Hematologic Malignancies has also motivated us to investigate the role of CXCL12 in pancreatic cancer. Among its many roles, CXCL12 and its receptors are known to contribute to metastasis, an elevated CXCL12 expression is known to be a Poor Prognosis factor in patients with certain solid tumors including pancreatic cancer. In January 2019, we presented new findings at ASCO GI identifying a potential association between CXCL12 expression and clinical benefit in patients with pancreatic cancer treated with tipifarnib. We believe these findings support the notion that tipifarnib is acting through modulation of the CXCL12 pathway, and furthermore, we believe they support further development of tipifarnib in pancreatic cancer. We're currently working with key opinion leaders and investigators on the design of a proof-of-concept study in this indication and we expect to provide an update on our plans in this area later this year. Although we see a significant opportunity for tipifarnib in many CXCL12 mediated solid tumor and Hematologic Malignancies, it's also important that we prioritize our efforts. In this regard our Phase 2 study of tipifarnib in myelodysplastic syndromes has been deprioritized and is not currently enrolling new patients, so that we may redirect those resources toward our effort in other CXCL12 pathway indications. Meanwhile, we've been actively working to further elucidate the biology of farnesyl transferase and the specific molecular mechanisms of action of tipifarnib. Our R&D team has made progress toward the identification of farnesylated protein targets as well as the potential mechanistic linkage between farnesyl transferase inhibition and CXCL12. We expect to have more to say on these topics at medical meetings this year. We've also expanded patent protection for tipifarnib to include AITL and certain CXCL12 expressing cancers, providing commercial exclusivity in the US to 2037. This is an important part of our strategy to generate intellectual property related to the use of tipifarnib in genetically defined patient populations and disease indications, and we're continuing to pursue additional US and ex-US patent. In summary, I'm very pleased with the progress we've made in our tipifarnib development program over the past year. We have better insights into why tipifarnib is active in different clinical settings and a better understanding of how to enrich for clinical activity. We're excited to explore these opportunities and broaden the potential clinical utility of tipifarnib, as we continue to execute on our registration-directed trial. Now, let's quickly turn our attention to our two emerging pipeline programs. Beginning with our ERK inhibitor KO-947. KO-947 is a potent and selective small molecule inhibitor of extracellular signal-related kinase, which we are advancing as a potential treatment for patients with tumors that have dysregulated activity in the mitogen-activated protein kinase or MAPK pathway. Our preclinical data suggests that KO-947 has anti-tumor activity in KRAS or BRAF-mutant adenocarcinomas, as well as certain subsets of squamous cell carcinomas. We continue to evaluate a number of doses and schedules for KO-947, and we anticipate having data from our Phase 1 trial in 2019. Our third product candidate is KO-539, a potent and selective small molecule inhibitor of the menin-mixed lineage leukemia or menin-MLL, protein-protein interaction. We've generated preclinical data that support the potential anti-tumor activity of KO-539 in genetically defined subset of acute leukemia including those with rearrangements or partial tandem duplication of the MLL gene, as well as those with oncogenic driver mutations in genes such as NPM1. I'm pleased to report the FDA has cleared our IND application, and we anticipate initiating our Phase 1 clinical trial of KO-539 in relapsed or refractory AML next quarter. With that, I'll now turn the call over to Marc Grasso for a discussion of our financial results for the fourth quarter and full year 2018.