Troy Wilson
Analyst · Leerink Partners. Your line is now open
Thank you, Pete, and thank you all for joining us this afternoon. Earlier today we were very pleased to announce our registration directed study of tipifarnib in recurrent or metastatic patients with HRAS mutant head and neck cancer has been initiated, and is now open for enrollment. As a reminder, the trial has two cohorts: SEQ-HN, a non-interventional screening and outcomes cohort, and AIM-HN, a treatment cohort. SEQ-HN is designed as a case-control study that should provide a better understanding of the natural history of patients with HRAS mutations while helping to identify patients for potential enrollment into AIM-HN. AIM-HN is designed to treat at least 59 patients with HRAS mutant HNSCC who have received prior platinum-based therapy. The primary endpoint of AIM-HN is overall response rate. The study has approximately 80% power to detect the difference between a null hypothesis of 15%, which is the point estimate of second-line therapy, ORR, for recurrent and metastatic disease and 30% in ORR considered of interest. We're targeting close to 100 clinical sites worldwide, and expect the study to take approximately two years to fully enroll. However, it's important to remember that based upon the statistical assumptions the trails could need as few as 15 confirmed responses in order to reject the null hypothesis and meets its primary efficacy endpoint. Based on feedback from the U.S. Food and Drug Administration, we believe that the trial, if positive, could support an application for accelerated approval. We are excited that this global multi-center trial is now underway. This milestone represents the culmination of nearly four years of rational drug development. And this first registration-directed trial embodies the promise of our precision medicine approach. To our knowledge tipifarnib is the first small-molecule inhibitor of HRAS oncogene in late stage clinical development. Thanks in part to advancements in cancer genetics and new molecular diagnostic tools, coupled with evidence-based clinical strategy and execution, we now believe we can identify subsets of patients most likely to respond to treatment. Last month, we reported an update on our positive Phase 2 study of tipifarnib in HRAS Mutant Head and Neck Squamous Cell Carcinomas or HNSCC and preliminary results in other HRAS mutant squamous cell carcinomas or SCCs at the ESMO 2018 Congress. As of the September 7, 2018 clinical data cutoff date, tumor size reductions were observed in nine of 11 evaluable patients, with five confirmed partial responses, including three patients with durable responses lasting more than 17 months. A sixth patient achieved a confirmed PR after the data cutoff. Four patients had stable disease including two patients who experienced prolonged disease stabilization lasting more than six months. Only one patient experienced progressive disease as best response. In addition, we're monitoring the progress of one additional HNSCC patient dosed off protocol who has an unconfirmed PR. The patient experienced a 40% tumor size reduction at first assessment, and is continuing to receive treatment. The ongoing Phase 2 trail also enrolled six patients in an additional cohort of other HRAS mutant SCCs. One of the two evaluable patients in this cohort achieved a confirmed PR and the other patient achieved prolonged disease stabilization lasting more than eight months. Four patients were not evaluable as of data cutoff date, including two patients who were pending initial efficacy assessments. As pioneers in the development of farnesyl transferase inhibitors as precision medicines, we are committed to advancing the science of how tipifarnib can best be used in patients. To that end, we were very encouraged by a novel observation that came from our updated ESMO. Our Phase 2 data showed a significant association between tumor HRAS mutant allele frequency and clinical benefit. By way of definition, allele frequency in this case is the measurement of mutated HRAS DNA in a patient's tumor compared to non-mutated HRAS or wild type DNA expressed as a percentage. As with most assay technology, a limited detection and a clinical cutoff must be established, for example, in the case of HER2 testing, a test detects the level of the HER2 protein in the cancer cells, from zero to three-plus. Generally, only cancers with the highest levels respond to the medicines that target HER2 positive breast cancers. Thus, although the assay can detect lower levels of the protein, the clinical cutoff for the assay is set at three-plus. In the same way, although current next-generation sequencing technologies can detect mutations lower than 1% allele frequency, an analysis of available tumor biopsy samples from patients enrolled in our ongoing Phase 2 study have shown that an allele frequency of at least 20% appears to be associated with clinical benefit in HNSCC or SCC patients with tipifarnib. Of the 13 HNSCC or SCC patients with a tumor HRAS mutant allele frequency greater than 20%, six achieved PRs, one achieved an unconfirmed PR and is ongoing, and two experienced disease stabilization greater than six months. In other words, meaningful clinical benefit was observed in nine of 13 patients with an allele frequency greater than 20%. In contrast, no meaningful clinical benefit was observed in the seven patients with an allele frequency less than 20%. We believe these findings give us insight into which patients are most likely to benefit from treatment with tipifarnib, namely those with HRAS mutant allele frequencies greater than 20%, and we have incorporated allele frequency in AIM-HN, as well as our ongoing Phase 2 studies. The question we continue to address is how does establishing an allele frequency cutoff impact the way we think about the addressable population. The short answer is if the number of addressable patients depends on where we set the allele frequency cutoff, specifically our internal data indicate approximately 8% of HNSCC patients have an HRAS mutant allele frequency greater than one percent. Data from a larger sample set in the Cancer Genome Atlas, or TCGA, indicates that approximately 5% of HNSCC patients have an HRAS mutant allele frequency greater than 20%. We believe that HNSCC patients with allele frequencies greater than 20% are those patients who are most likely to experience clinical benefit from treatment with tipifarnib as a monotherapy. Meanwhile, we are investigating how tipifarnib may also address the unmet medical need of those patients with allele frequencies less than 20%. A second takeaway from the data presented at ESMO is we now have a better understanding of the starting dose. Patients in the Phase 2 trial received oral doses ranging from 600 to 900 milligrams twice daily. Although our early clinical experience suggested that 900 milligrams might be the optimal dose. After expanding into additional sites around the world, we've determined 600 milligrams twice daily to be the recommended dose. As presented at ESMO, four of the responses in two disease stabilizations greater than six months were observed in patients while in treatment with the 600 milligram twice-daily dose, indicating that the dose is sufficient to drive clinical activity. Furthermore, by selecting patients with tumors with high HRAS mutant allele frequencies and increased sensitivity to tipifarnib, we believe we may achieve a higher therapeutic index in the clinic. As such, we've introduced a minimum tumor HRAS mutant allele frequency of 20% in our registration directed trial, and are using 600 milligrams orally twice daily as the starting dose. We continue to be very encouraged by the growing body of data that support the potential of tipifarnib as a treatment for squamous cell carcinomas characterized by HRAS mutations. With our registration-directed trial of tipifarnib in HRAS mutant HNSCC now underway, we remain focused on our goal of generating a data package to support an application for marketing approval in that indication, while we also work to broaden the potential of tipifarnib in both HRAS mutant and non-mutant cancers. In that regard, we're encouraged by preliminary signals of clinical activity observed in patients with HRAS mutant SCC as we believe this may represent a near-term opportunity to expand the use of tipifarnib into a broader set of HRAS mutant cancers. In addition, we believe tipifarnib may have utility to address the unmet medical need of those HNSCC patients with low tumor HRAS mutant allele frequencies. Long-term, our development strategy for tipifarnib is to advance toward earlier lines of therapy and ultimately to treat patients with HRAS mutant SCCs in the continuum of systemic treatment setting. Now, let's turn our attention to hematologic malignancies, which represent another significant opportunity for tipifarnib. As a reminder, previously conducted studies by Janssen demonstrated that tipifarnib can drive clinical activity in certain patients with hematologic malignancies. However, no molecular mechanism of action was identified that could explain its activity in those populations. Approximately one year ago, we presented new findings that identified activation of the CXCL12 pathway and bone marrow homing of myeloid cells as potential biomarkers of tipifarnib's activity in certain hematologic malignancies, including PTCL, MDS, CMML, and AML. Based on these observations, we've been working to validate the CXCL12 pathway as a therapeutic target of tipifarnib, and to prospectively validate potential biomarkers in our ongoing Phase 2 trials. PTCL was the first of the three trials to begin, and has been actively enrolling patients into two expansion cohorts, one defined by histology, the other by genetics. The first cohort includes patients with angioimmunoblastic T-cell lymphoma, or AITL, an aggressive form of T-cell lymphoma. We Call preliminary data from our Phase 2 trial tipifarnib unselected population of patients with PTCL showed that patients having elevated levels of CXCL12 gene expression had a higher rate of clinical benefit in terms of objective response rate and progression free survival of the three peers two occurred in the two patients on study with a AITL. These findings are consistent with published data that show patients with AITL expressed high levels of CXCL12. The second cohort includes patients with PTCL not otherwise specified who have the absence of a single nucleotide variation in the three prime untranslated region of the CXCL12G. We estimate that the combined addressable populations of patients with AITL and CXCL12 positive PTCL account for approximately 40% of PTCL cases. Despite several approvals over the past decade, we believe the treatment of relapsed and/or refractory PTCL remains a significant unmet medical need. Three of the more recent launches, pralatrexate, romidepsin, and belinostat were approved based on single-arm clinical trials of fewer than 130 patients each with response rates in the range of 25% to 27% and only two to three months of median progression free survival in unselected populations. We believe the CXCL12 pathway holds promise for identifying patients who will respond to tipifarnib and we look forward to showing initial prospective data from the AITL and CXCL12 positive cohorts in our Phase 2 trial in PTCL at ASH in December. Our goal is to provide additional biomarker and rich data from other hematologic indications in 2019. Now a quick look at our two emerging pipeline programs before we turn to the financials, our Phase 1 dose escalation trial of KO-947 in solid tumors continues. As we work to define a dosing schedule that will enable us to evaluate KO-947 in genetically selected patients whose tumors are sensitive to ERK inhibition. We anticipate having data from the dose escalation portion of the trial available in 2019. Meanwhile, we're currently conducting INDA enabling studies for our menin-MLL inhibitor KO-539 and our targeting an IND submission in the first quarter of 2019. With that, I'll now turn the call over to Marc Grasso for a discussion of our financial results for the third quarter of 2018.