Mark Gelder
Analyst · Guggenheim. You may begin
So, thank you, Steve. And thanks to all of those who have joined us today. I’ll begin today with our narazaciclib program. As Steve mentioned, narazaciclib is a multi-targeted kinase inhibitor that targets CDK 4 and 6 as well as several additional kinases at low nanomolar concentrations. We believe it has the potential to be a highly differentiated therapy due to several key characteristics such as its preclinical safety profile, which shows that it appears to cause less myelosuppression and neutropenia compared to palbociclib, the most widely prescribed CDK4/6 inhibitor today. Preclinical data suggesting potent inhibition of CDK2, a kinase understood to be essential to DNA replication and one of several potential mechanisms of resistance in the hormone receptor positive HER2-negative metastatic breast cancer population to the approved CDK4/6 inhibitors. Additionally, its ability to inhibit ARK5, which promotes the survival of cancer cells in hypoxic microenvironments, serves an important role in cell adhesion and metastasis and may play a role in drug resistance. Its ability to inhibit CSF1 receptor, or CSF1R, which results in the stimulation of antitumor immunological effects and its ability to inhibit the growth of cancer cell lines resistant to palbociclib. We believe this differentiated pharmacologic profile positions narazaciclib to be studied even beyond areas where other CDK4/6 inhibitors inhibitors are currently approved both as a single agent and in combination with a myriad of other anticancer compounds. To begin evaluating this hypothesis, narazaciclib is being studied in two Phase 1 trials: one in the United States and one in China, where we are collaborating with HanX Biopharmaceuticals. Our U.S. study is evaluating a continuous daily dosing schedule of narazaciclib and is enrolling patients with a variety of advanced cancers. If this study shows a favorable safety profile for continuous daily dosing of narazaciclib, it will allow us to further differentiate our lead asset from both palbociclib and the other approved CDK4/6 inhibitor, ribociclib, which are both dosed on a schedule of three weeks on, one week off. These agents are associated with bone marrow toxicity leading to significant myelosuppression or low white blood cell counts and thus, as I mentioned, require a three weeks on, one week off dosing schedule. I’m pleased to say today that the safety findings we have seen in nerazacyclib’s Phase 1 trial thus far have been very promised. No dose-limiting toxicities have been observed in either trial including the lack of clinically meaningful neutropenia. The trial in the U.S. remains ongoing and is currently enrolling patients into its fourth dose cohort, which is evaluating 160 milligrams orally administered daily. Narazaciclib’s complementary Phase 1 trial in China is also moving along very well as our partner, HanX Biopharmaceuticals, has completed the trial’s fourth dose escalation cohort which evaluated the 160-milligram dose of narazaciclib administered orally with a three week on, one week off dosing schedule. We have not seen any dose-limiting toxicities in this trial, and HanX is now enrolling the fifth dose cohort at 200 milligrams orally with a three week on, one week off schedule and is currently working to prepare a protocol amendment to enable the evaluation of higher doses. Ultimately, we expect the data from narazaciclib Phase 1 program to enable the selection of a recommended Phase 2 dose later this year. This will then be utilized in future trials, including a Phase 2 basket trial enrolling patients with several different types of cancer such as CDK4/6 inhibitor refractory hormone receptor positive HER2-negative metastatic breast cancer. Narazaciclib’s potential in this indication is supported by the preclinical data I mentioned earlier, which shows it inhibiting the growth of cancer cell lines resistant to palbociclib. We are also planning one or more additional clinical trials of narazaciclib, as Steve mentioned, which will be designed to evaluate its safety and efficacy alone or in combination with other anticancer agents. We are still developing these specific plans for these trials, and we’ll share them with you once they are finalized. Moving on. I’d now like to turn your attention to rigosertib’s investigator sponsor program, starting with the program’s most recent data update. This update occurred in December when we reported preliminary clinical data at a European Dermatology and Venereology Annual Conference showing rigosertib’s ability to inhibit PLK1 translates into activity against RDEB-associated squamous cell carcinoma. As Steve previewed, RDEB-associated squamous cell carcinoma is an ultra rare and invariably fatal condition caused by a lack of Type 7 collagen protein expression. Type 7 collagen is responsible for anchoring the skin’s interlayer to its outer layer and due to its absence RDEB patients suffer from extreme skin fragility and chronic wound formation. Over time, many of these patients develop squamous cell carcinoma and the overexpression of PLK1. The disease and its tumors are highly aggressive with a cumulative risk of death of greater than 78% by age 55. The standard of care for these patients is tragically poor as targeted therapies, conventional chemo and radiation therapies as well as immunotherapy provides limited response rates and poor durability of response. The trial’s investigators presented data from an RDEB patient. This patient had a history of multiple unresectable squamous cell carcinomas that were unresponsible to multiple prior treatments, including the PD-1 inhibitor, cemiplimab. Notably, when treated with rigosertib monotherapy, the patient experienced a sustained complete response without signs of any further disease following 13 treatment cycles. To see a complete response in this indication, particularly in a patient that had failed multiple prior therapies, is a very promising observation that we believe warrants further study. It confirms rigosertib’s activity against PLK1 in the clinic and positions it as a novel treatment option that can greatly improve upon the current standard of care in a very challenging indication. We look forward to the continued advancement of this clinical trial and will provide additional updates as appropriate. In addition to this investigator-sponsored trial in RDEB-associated squamous cell carcinoma, rigosertib is also being evaluated in combination with the PD-1 inhibitor, nivolumab, in an investigator-sponsored Phase 1/2a trial in KRAS-mutated non-small cell lung cancer patients who have previously failed checkpoint inhibitor therapy. This trial leverages rigosertib drawl as an immune modulator that targets the mutated KRAS pathway and build upon preclinical we’ve discussed in the past that demonstrates rigosertib’s ability to synergize with checkpoint inhibitors by reversing cold immunosuppressive tumor micro environments through the upregulation of novel antigens such as CD40 on cancer cells and thereby recruit host T cells that the immune modulator can stimulate to attack the tumor. Preliminary results from this trial, which were discussed at like during our last earnings call, support the potential anticancer activity of the rigosertib-nivolumab combination. They also demonstrate rigosertib’s applicability across multiple KRAS mutations, which differentiates it from other RAS pathway modulators, that only target a subset of patients with a particular mutation and suggest that rigosertib may enhance checkpoint inhibitor efficacy. We continue to build on these results through the trial sustained progress with its dose expansion phase currently enrolling patients and additional data expected later this year. An additional study that will allow for the evaluation of increased doses of rigosertib that is part of the doublet with nivolumab is also under consideration since the maximum tolerated dose was not reached to date. Beyond non-small cell lung cancer, we are seeking to further leverage rigosertib synergy with checkpoint inhibitors through a planned investigation trial in metastatic melanoma that will evaluate it in combination with the PD-1 inhibitor, pembrolizumab. With anti-PD-1 resistance occurring in 40% to 60% of metastatic melanoma patients, there is a pressing unmet need to enhance the efficacy of these agents that we believe rigosertib may help address. This hypothesis is supported both by the preliminary clinical results in checkpoint inhibitor refractory non-small cell lung cancer I just mentioned as well as by the preclinical data. The protocol for this investigator-sponsored melanoma trial is finalized, and we expect to open the study later in the first half of this year. Finally, before handing the call over to Mark, I’ll just once again remind everybody that while we are very interested in furthering rigosertib’s clinical development to investigator-sponsored trials, we remain primarily focused internally on our lead narazaciclib program. And with that, I’ll turn the call over to Mark Guerin for a discussion of our 2021 financial results. Mark?