UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

☒      QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the Quarterly Period Ended September 30, 2020March 31, 2021

OR

☐      TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the Transition Period from       to       

Commission File Number: 1-35447

APTOSE BIOSCIENCES INC.

(Exact Name of Registrant as Specified in Its Charter)

251 Consumers Road, Suite 1105  

Toronto, Ontario, Canada M2J 4R3
(Address of principal executive offices)

647-479-9828

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☒☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

Securities registered pursuant to Section 12(b) of the Act:

As of November 10, 2020May 4, 2021 the registranthad 88,861,73788,943,243 common shares outstanding.

TABLE OF CONTENTS

PART I—FINANCIAL INFORMATION

Item 1 – Financial Statements

Condensed Consolidated Interim Financial Statements

(Unaudited)

APTOSE BIOSCIENCES INC.

For the three and nine months ended September 30,March 31, 2021 and 2020 and 2019

APTOSE BIOSCIENCES INC.

Condensed Consolidated Interim Statements of Financial Position

(Expressed in thousands of US dollars)

(unaudited)

See accompanying notes to condensed consolidated interim financial statements (unaudited).

Subsequent events (note 12)

APTOSE BIOSCIENCES INC.

Condensed Consolidated Interim Statement of Loss and Comprehensive Loss

(Expressed in thousands of US dollars, except for per common share data)

(unaudited)

See accompanying notes to condensed consolidated interim financial statements (unaudited).

APTOSE BIOSCIENCES INC.

Condensed Consolidated Interim Statements of Changes in Shareholders’ Equity

(Expressed in thousands of US dollars, except for per common share data)dollars)

(unaudited)

See accompanying notes to condensed consolidated interim financial statements (unaudited).

APTOSE BIOSCIENCES INC.

Condensed Consolidated Interim Statements of Cash Flows

(Expressed in thousands of US dollars)

(unaudited)

See accompanying notes to condensed consolidated interim financial statements (unaudited).

To calculate the lease liability, the lease payments in the table above were discounted over the remaining term of the leases using the Company’s incremental borrowing rate as at January 1, 2019 for existing leases at the time of adopting the Topic 842, and for new leases after the date adoption, as at the date of the execution date of the new lease. The following table presents the weighted average remaining term of the leases and the weighted average discount rate:

Right-of-use assets obtained in exchange for operating lease liabilities are as follows:

Operating lease costs and operating cash flows from our operating leases are as follows:

The Company uses historical data to estimate the expected dividend yield and expected volatility of its common shares in determining the fair value of stock options. The expected life of the options represents the estimated length of time the options are expected to remain outstanding.

The following table presents the vesting terms of options granted in the period:

Restricted share units

The Company has a stock incentive plan (SIP) pursuant to which the Board may grant stock-based awards comprised of restricted stock units or dividend equivalents to employees, officers, consultants, independent contractors, advisors and non-employee directors of the Company. Each restricted unit is automatically redeemed for one common share of the Company upon vesting. The following table presents the activity under the SIP plan for the ninethree months ended September 30,March 31, 2021 and 2020 and 2019 the units outstanding.

On March 10, 2020, the Company granted 645,000 restricted share units (RSUs) withhaving a vesting term of three months. On May 5, 2020, the vesting term on the RSUs was extended from three months to four months. On July 10, 2020, all of these restricted share units were vested and were redeemed for 645,000 common shares.

On June 3, 2019, the Company granted 80,000 restricted share units (RSUs), 40,000 of which have a vesting term of three months and the balance have a vesting term of one year. On May 5, 2020, the vesting term on the balance was extended from one year to one year and one month. On July 2, 2020, the remaining of these restricted share units were vested and were redeemed for 40,000 common shares.

The grant date fair value of the March 10, 2020 and June 3, 2019 RSUs werewas determined as the closing value of the common shares of the Company on the Nasdaq Stock Market on the date prior to the date of grant.

The Company recorded share-based payment expense related to stock options and RSUs as follows:

Item 2 – Management’s Discussion and Analysis of Financial Condition and Results of Operations

This Quarterly Report on Form 10-Q contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and is subject to the safe harbor created by those sections. For more information, see “Cautionary Note Regarding Forward-Looking Statements.” When reviewing the discussion below, you should keep in mind the substantial risks and uncertainties that impact our business. In particular, we encourage you to review the risks and uncertainties described in “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2019,2020, as updated and supplemented in Part II, Item 1A in this Quarterly Report on Form 10-Q. These risks and uncertainties could cause actual results to differ materially from those projected or implied by our forward-looking statements contained in this report. These forward-looking statements are made as of the date of this management’s discussion and analysis, and we do not intend, and do not assume any obligation, to update these forward-looking statements, except as required by law.

The following discussion should be read in conjunction with our condensed consolidated interim financial statements and accompanying notes contained in this Quarterly Report on Form 10-Q and our audited financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2019.2020.

All amounts are expressed in United States dollars unless otherwise stated.

OVERVIEW

Aptose Biosciences Inc. (“we”, “our”, “us”, “Aptose” or the “Company”) is a science-driven biotechnology company advancing first-in-class targeted agents to treat life-threatening cancers, such as acute myeloid leukemia (“AML”), high-risk myelodysplastic syndromes (“MDS”), chronic lymphocytic leukemia (“CLL”) and other hematologic malignancies. Based on insights into the genetic and epigenetic profiles of certain cancers and patient populations, Aptose is building a pipeline of novel oncology therapies directed at dysregulated processes and signaling pathways. Aptose is developing targeted medicines for precision treatment of these diseases to optimize efficacy and quality of life by minimizing the side effects associated with conventional therapies. We currently have in development two molecules: CG026806 (“CG-806”)luxeptinib (CG-806) and APTO-253, both being evaluated for safety, tolerability, pharmacokinetics and signals of efficacy in Phase 1 clinical trials. Each molecule is described below.

CG-806Luxeptinib is an orally administered, highly potent first-in-class FMS-like tyrosine kinase 3 (“FLT3”)/Bruton’s tyrosine kinase (“BTK”) inhibitor that selectively targets defined clusters of kinases that are operative in myeloid and lymphoid hematologic malignancies. This mutationally agnostic small molecule anticancer agent is currently being evaluated in a Phase 1a/b study for the treatment of patients having B-cell malignancies including classic CLL, small lymphocytic lymphoma (“SLL”) and certain non-Hodgkin’s lymphomas (“NHL”) that are resistant/refractory/intolerant to other therapies. In addition, Aptose recently received IND allowance and has initiated patient dosingUnder a separate Investigational New Drug (“IND”), luxeptinib is being evaluated in a Phase 1a/b study to develop CG-806 for the treatment of patients with relapsed/refractory acute myeloid leukemiaAML (“R/R AML”), including the emerging populations resistant to FLT3 inhibitors. In this trial of patients with R/R AML, the CG-806 starting dose of 450 mg BID was selected because the plasma from B-cell cancer patients at that dose completely inhibited phospho-FLT3, suggesting that this starting dose might be active in the AML patient population. It is important to note that CG-806 now is undergoing formal clinical development in bothhoped luxeptinib can serve patients across lymphoid and myeloid hematologic malignancies.malignancies and combine well with other agents to extend its application to multiple lines of therapy.

APTO-253 is a first-in-class small molecule therapeutic agent that clinically inhibits expression of the MYC oncogene without causing, to date, general myelosuppression of the bone marrow. The MYC oncogene is overexpressed across many hematologic cancers, including AML and certain B cell malignancies, as well as certain solid tumor indications. MYC acts as a transcription factor that regulates cell growth, proliferation, differentiation and apoptosis, and overexpression of MYC amplifies new sets of genes to promote survival of cancer cells. APTO-253 suppresses expression of the MYC oncogene in AML cells and depletes those cells of the MYC oncoprotein, leading to apoptotic cell death. APTO-253 is currently being evaluated in a Phase 1b1a/b study for the treatment of patients with R/R AML and high-risk MDS. APTO-253 may serve as a safe and effective MYC inhibitor for AML/MDS patients that combines well with other agents and does not significantly impact the normal bone marrow.

PROGRAM UPDATES

CG-806

Indication and Clinical Trials:

CG-806 is being developed with the intent to deliver the agent as an oral therapeutic for the treatment of R/R AML and for the treatment of a spectrum of B cell malignancies (including but not limited to CLL, SLL and NHL).

On March 25, 2019, we announced that the U.S Food and Drug Administration (“FDA”) granted Aptose Investigational New Drug (“IND”) allowance to initiate its Phase 1a/b clinical trial for CG-806. The clinical trial is a multicenter, open label, dose-escalation study with additional optional expansion cohorts to assess the safety, tolerability, pharmacokinetics and pharmacodynamic effects, and preliminary efficacy of CG-806 in patients with CLL, SLL or NHL. In this study, CG-806 is administered in gelatin capsules twice daily (“BID”) during a 28-day cycle.

As of the date of this report, we have initiated thirty clinical sites for the Phase 1a/b trial in patients with CLL/SLL or NHL which include specialty regional cancer care centers as well as large hospitals and key academic institutions. As of the date of this report, we have completed the first, second, third and fourth dose levels (150 mg, 300 mg, 450 mg and 600 mg BID, respectively). Cohort 5 (750mg) enrollment is ongoing. Under an FDA-approved accelerated titration protocol, only one patient was required at each of the first two dose levels, followed by three patients at each dose level thereafter. Intra-patient dose escalation is allowed if the higher dose is safe in three or more patients, and additional patients may be enrolled at dose levels previously declared safe. To date, we have reported that among enrolled patients with an array of B-cell malignancies, three classic CLL patients have received CG-806 and all three demonstrated inhibition of phospho-BTK and “on-target” lymphocytosis, indicating target engagement and pharmacologic activity of CG-806. As CG-806 moves from low/intermediate dose levels and into the higher dose levels, it is hoped that an optimal dose can be selected that demonstrates formal clinical responses without excessive toxicity.

Aptose is also advancing CG-806 into myeloid malignancies, with an initial focus on AML, in a separate Phase 1a/b trial. On June 29, 2020, the Company announced that it had received allowance from the FDA to proceed into a study in R/R AML with a starting dose of 450 mg BID, and subsequently on October 19, 2020, announced that it had initiated dosing of the first patient with AML. As of the date of this report we have initiated five clinical sites for the Phase 1a/b trial.

The clinical trial is a multicenter, open label, dose-escalation study with additional optional expansion cohorts to assess the safety, tolerability, pharmacokinetics and pharmacodynamic effects, and preliminary efficacy of CG-806 in patients with R/R AML. In this study, CG-806 is administered in gelatin capsules BID during a 28-day cycle. Our strategy was to identify a starting dose of CG-806 that we believe could be therapeutically active in critically ill patients with R/R AML. In our ongoing Phase 1a/b study in patients with CLL and other B-cell malignancies, 450 mg BID CG-806 delivered plasma levels that completely inhibited phospho-FLT3 in a plasma inhibitory activity (PIA) reporter cell assay, suggesting that the 450 mg BID dose may be active in patients with AML. Aptose plans to dose escalate beyond the 450 mg BID dose level, provided the 450 mg BID dose level is safe and well tolerated in R/R AML patients. Based on strong preclinical evidence of CG-806’s activity against AML – including demonstration of mutation-agnostic and genotype-agnostic potency, particularly compared against other FLT3 inhibitors, and its ability to safely cure AML in murine leukemia models – we believe CG-806 may offer hope to the fragile and difficult-to-treat AML patient population.

The FDA has granted orphan drug designation to CG-806 for the treatment of patients with AML. Orphan drug designation is granted by the FDA to encourage companies to develop therapies for the treatment of diseases that affect fewer than 200,000 individuals in the United States. Orphan drug status provides research and development tax credits, an opportunity to obtain grant funding, exemption from FDA application fees and other benefits. The orphan drug designation also provides us with seven additional years of marketing exclusivity in this indication.

Manufacturing:

During fiscal years 2017 and 2018, we created a scalable chemical synthetic route for the manufacture of CG-806 drug substance and have scaled the manufacture of API (active pharmaceutical ingredient, or drug substance) to multi-kg levels, we completed the manufacture of a multi-kg batch of API under Good Manufacturing Product (“GMP”) conditions as our API supply for our first-in-human clinical trials, and we manufactured under GMP conditions two dosage strengths of capsules to serve as our clinical supply in those human studies. During fiscal 2019, we completed successful manufacture of multiple batches of API and drug product, and planned numerous GMP production campaigns to supply the ongoing trial and planned trials into the future. To date we have been able to manufacture API and capsules to support clinical supplies under GMP conditions. We are continuing our manufacturing campaigns in the current 2020 fiscal period and have commenced scale-up and tech transfer activities to support additional manufacturing capacity for the ongoing and planned clinical trials of CG-806. Additional research and development funds are being utilized to support exploratory formulation studies in an ongoing effort to craft a superior formulation for later stage development of CG-806.

Data presentations:

On April 27, 2020, we presented the early clinical data on CG-806 at the AACR Virtual Annual Meeting I (April 27-28) in lieu of the live oral presentation originally planned. A video summary of Abstract # 9967 - Early clinical findings from a Phase 1a/b dose escalation trial to evaluate the safety and tolerability of CG-806 in patients with relapsed or refractory CLL/SLL or non-Hodgkin’s lymphomas described the first-in-human tests of CG-806 which are being carried out in a Phase 1a/b clinical study in patients with significant unmet needs including patients with relapsed or refractory CLL, SLL or NHL who had been failed by or been intolerant to two lines of established therapy. We noted that the second patient, treated at the 300 mg BID dose level, represented a classic CLL patient that developed a brisk lymphocytosis (evidence of BTK target engagement and evidence of pharmacologic activity), and that enrollment was continuing.

On June 12, 2020, we presented new clinical data on CG-806 in a poster presentation at the 25th Congress of the EHA. The poster, Early Clinical Findings from a Phase 1 a/b Dose Escalation Trial to Evaluate the Safety and Tolerability of CG-806 in Patients with Relapsed or Refractory CLL/SLL or Non-Hodgkin’s Lymphomas (EHA2020 Abstract# EP711), reviewed CG-806 data for eight patients (as of the data cut-off date on May 5, 2020) with relapsed or refractory CLL,SLL or NHL in the first in-human Phase 1a/b, open-label, single arm, multicenter dose-escalation clinical study. Data from the ongoing trial demonstrated CG-806 was well-tolerated in patients treated at 150 mg, 300 mg, 450 mg BID over multiple cycles, with no dose-limiting toxicities or serious adverse events observed, supporting continued dose escalation. CG-806 treatment achieved human steady state PK levels known to be effective in murine tumor models and led to complete inhibition of phospho-BTK and multiple CLL survival pathways. CG-806 treatment also led to lymphocytosis in both classic CLL patients entering study with elevated lymphocyte counts and led to complete inhibition of phospho-FLT3, suggesting that dose levels evaluated in this study may be therapeutic in patients with AML.

On June 22, 2020, we presented new preclinical data on CG-806 in a poster presentation at the AACR Virtual Annual II 2020. The poster, CG-806, a First-in-Class FLT3/BTK Inhibitor, and Venetoclax Synergize to Inhibit Cell Proliferation and to Induce Apoptosis and Aggressive B-cell Lymphomas, illustrated how CG-806 simultaneously inhibits the driver BCR pathway and PI3K/AKT, NFᴋB and MAPK-mediated rescue pathways to kill aggressive double-hit and double-expressor B-cell lymphoma cells. Overall, the presented work provided additional mechanistic evidence to support the clinical development of CG-806 as a single agent or in combination with venetoclax in patients with aggressive B-cell lymphomas harboring unfavorable BCL2/MYC/BCL6 translocations and / or overexpression.

APTO-253

Phase 1b Trial

APTO-253, a small molecule inhibitor of MYC gene expression, is being evaluated by Aptose in a Phase 1b clinical trial in patients with R/R hematologic malignancies, particularly R/R AML and high-risk MDS. The Phase 1b, multicenter, open-label, dose-escalation clinical trial of APTO-253 is designed to assess the safety, tolerability, pharmacokinetics and pharmacodynamic responses and efficacy of APTO-253 as a single agent and determine the recommended Phase 2 dose. APTO-253 is being administered once weekly, over a 28-day cycle. The dose escalation stage of the study could potentially enroll up to 20 patients with R/R AML or high-risk MDS. The study is designed to then transition, as appropriate, to single-agent expansion cohorts in R/R AML and/or high-risk MDS.

As of the date of this report, we have multiple active sites recruiting patients in the dose escalation stage of the trial. As of the date of this report, we have completed enrollment and treatment of patients on the first, second, third and fourth dose levels (20, 40, 66, and 100 mg/m², respectively). Under an FDA-approved accelerated titration protocol, only one patient was required at each of the first two dose levels, followed by three patients at each dose level thereafter. Aptose is currently enrolling and treating patients in the fifth dose level (150 mg/m²) of APTO-253. During the second quarter of 2020, the FDA allowed an amendment for Aptose to initiate more aggressive dose escalations with APTO-253, provided the tolerability profile remains favorable. The first four dosing cohorts have enrolled a mix of patients with AML and MDS. To date, we have observed meaningful reductions in MYC expression in peripheral blood mononuclear cells (PBMCs) from treated patients with AML and MDS, demonstrating MYC target engagement and mechanistic proof of concept in different indications.

Manufacturing:

We are continuing to manufacture additional drug substance and drug product for use in the ongoing trial.

We are exploring additional drug delivery methods for APTO-253 and plan to initiate additional non-clinical studies for solid tumor and hematologic cancer development. As preparing, submitting, and advancing applications for regulatory approval, developing drugs and drug product and clinical trials are sometimes complex, costly, and time-consuming processes, an estimate of the future costs is not reasonable at this time.

Impact of COVID 19COVID-19 on our Research Programs:Programs:

We are advancing first-in-class targeted agents to treat life-threatening cancers that, in most cases, are not elective for patients and require immediate treatment. However, COVID-19 has caused global economic and social disruptions that could adversely affect our ongoing or planned research and development and clinical trial activities including enrollment of patients in our ongoing clinical trials, collection and analysis of patient data and eventually, the reporting of top-line results from our trials.

Our team proactively addressed these new challenges swiftly and appropriately, implementing safeguards and procedures to ensure both the safety of our employees and stakeholders, and accommodate the potential challenges due to COVID-19. Aptose was early in directing its employees to work-from-home and provided the tools to minimize productivity disruptions. Our Clinical Operationsclinical operations team reached out to active and future clinical sites to determine their needs and challenges and assist where possible, including virtual monitoring of patients, which reduces patients’ visits. We also have contacted our drug manufacturers to identify any potential supply chain disruptions and are adjusting accordingly. During the early part of the first quarter of 2020, we began to carefully monitor the potential impact of COVID-19, and on a regular basis, we communicated with investigators at our clinical sites to gain an evolving understanding of competing COVID-19 related activities and clinical trial related activities.

In the beginning of April 2020, we learned that some of our larger clinical sites that are impacted by COVID-19 may either postpone or face delays in the enrollment of patients on all on-going clinical trials due to a number of factors, including the re-allocation of resources and to avoid clinical trial patients being exposed to COVID-19. Such measures taken at the clinical sites could lead to a slowdown in the enrollment of patients on our trials at these sites. To minimize the impact of COVID-19, we focusedcontinue to focus efforts in parallel on our other larger clinical sites and regional cancer care sites that are not/less impacted by COVID-19 to recruit patients into the fourth cohort.COVID-19. While it is difficult to estimate the duration and impact of COVID-19 on the larger clinical sites and regional cancer care sites, as of the date of this report, we have not experienced and do not foresee material delays to the enrollment of patients or timelines for the CG-806 Phase 1a/b B-cell malignancy trialluxeptinib clinical trials due to the variety of clinical sites that we have actively recruited for this trial.recruited. APTO-253, which is administered intravenously, requires the need for hospital / clinical site resources to assist and monitor patients during each infusion and based on the current conditions caused by COVID-19, future enrollment of patients on this trial is likely to be negatively impacted.

While as of the date of this report we have not experienced any material delays in initiating our CG-806 Phase 1 clinical study in AML due to COVID-19, we are conducting site initiation visits remotely which could result in delays in site activations and negatively impact this trial. Additionally, COVID-19 could negatively impact patient enrollment if our clinical sites are unable to enroll patients due to either a lack of administrative resources at their sites or decisions made at the clinical sites to limit patient exposure to COVID-19.

As of the date of this report, we have not experienced material delays in the manufacturing of CG-806luxeptinib or APTO-253 related to COVID-19. Should our manufacturers experience shortages in staffing or be required to shut down their facilities due to COVID-19 for an extended period of time, our trials may be negatively impacted.

PROGRAM UPDATES

Luxeptinib (CG-806)

Indication and Clinical Trials:

Luxeptinib is being developed with the intent to deliver the agent as an oral therapeutic for the treatment of R/R AML and for the treatment of a spectrum of B cell malignancies (including but not limited to CLL, SLL and NHL).

On March 25, 2019, we announced that the U.S. Food and Drug Administration (“FDA”) granted Aptose IND allowance to initiate its Phase 1a/b clinical trial for luxeptinib. The clinical trial is a multicenter, open label, dose-escalation study with additional optional expansion cohorts to assess the safety, tolerability, pharmacokinetics and pharmacodynamic effects, and preliminary efficacy of luxeptinib in patients with CLL, SLL or NHL. In this study, luxeptinib is administered in gelatin capsules twice daily (BID during a 28-day cycle).

As of the date of this report, we have multiple active clinical sites for the Phase 1a/b trial in patients with CLL/SLL or NHL which include specialty regional cancer care centers as well as large hospitals and key academic institutions. As of the date of this report, we have completed the first, second, third and fourth dose levels (150 mg, 300 mg, 450 mg and 600 mg BID, respectively). Cohort 5 (750mg) enrollment is ongoing. Under an FDA-approved accelerated titration protocol, only one patient was required at each of the first two dose levels, followed by three patients at each dose level thereafter. Intra-patient dose escalation is allowed if the higher dose is safe in three or more patients, and additional patients have been and may continue to be enrolled at dose levels previously declared safe. To date, we have reported that among treated patients with an array of B-cell malignancies, we have observed inhibition of phospho-BTK and modest tumor reductions in different tumor types, indicating target engagement and pharmacologic activity of luxeptinib. As luxeptinib moves from low/intermediate dose levels and into the higher dose levels, it is hoped that an optimal dose can be selected that demonstrates formal clinical responses without excessive toxicity.

We are also advancing luxeptinib into myeloid malignancies, with an initial focus on AML, in a separate Phase 1a/b trial. On June 29, 2020, we announced that we had received allowance from the FDA to proceed into a study in R/R AML with a starting dose of 450 mg BID, and subsequently on October 19, 2020, announced that we had initiated dosing of the first patient with AML. Encouraging anti-leukemic activity has been observed at the first dose level of 450mg bid, including one complete response in a patient at the 450mg dose level. Aptose completed the 450 mg bid dose cohort and initiated dosing of patients with the 600 mg bid dose. The clinical trial is a multicenter, open label, dose-escalation study with additional optional expansion cohorts to assess the safety, tolerability, pharmacokinetics and pharmacodynamic effects, and preliminary efficacy of luxeptinib in patients with R/R AML. In this study, luxeptinib is administered in gelatin capsules BID during a 28-day cycle. As of the date of this report we have multiple active clinical sites for the Phase 1a/b trial. Based on strong preclinical evidence of luxeptinib’s activity against AML – including demonstration of mutation-agnostic and genotype-agnostic potency, particularly compared against other FLT3 inhibitors, and its ability to safely cure AML in murine leukemia models – we believe that luxeptinib may offer hope to the fragile and difficult-to-treat AML patient populations. The FDA has granted orphan drug designation to luxeptinib for the treatment of patients with AML. Orphan drug designation is granted by the FDA to encourage companies to develop therapies for the treatment of diseases that affect fewer than 200,000 individuals in the United States. Orphan drug status provides research and development tax credits, an opportunity to obtain grant funding, exemption from FDA application fees and other benefits. The orphan drug designation also provides us with seven additional years of marketing exclusivity in this indication.

Manufacturing:

During fiscal years 2017 and 2018, we created a scalable chemical synthetic route for the manufacture of luxeptinib drug substance and have scaled the manufacture of API (active pharmaceutical ingredient, or drug substance) to multi-kg levels, we completed the manufacture of a multi-kg batch of API under GMP conditions as our API supply for our first-in-human clinical trials, and we manufactured under GMP conditions two dosage strengths of capsules to serve as our clinical supply in those human studies. During fiscal 2019 and 2020, we completed successful manufacture of multiple batches of API and drug product and planned numerous GMP production campaigns to supply the ongoing trial and planned trials into the future. To date we have been able to manufacture API and capsules to support clinical supplies under GMP conditions. We are continuing our manufacturing campaigns in the current 2021 fiscal period and continue scale-up and tech transfer activities to support additional manufacturing capacity for the ongoing and planned clinical trials of luxeptinib. Additional research and development funds are being utilized to support exploratory formulation studies in an ongoing effort to craft an improved formulation for later stage development of luxeptinib.

Preclinical and Clinical Updates:

Key presentations on luxeptinib at recent scientific forums are as follows:

On April 15, 2018, at the 2018 Annual Meeting of the American Association for Cancer Research (“AACR”), we presented with the OHSU Knight Cancer Institute preclinical data demonstrating that luxeptinib, a pan-FLT3/pan-BTK inhibitor, demonstrates broader activity and superior potency to other FLT3 and BTK inhibitors against primary bone marrow samples from patients with hematologic malignancies. We also presented preclinical data demonstrating that luxeptinib targets multiple pathways to kill diverse subtypes of AML and B-cell malignancies in vitro.

On June 15, 2018, at the 23rd Congress of the European Hematology Association (“EHA”), we presented, during a poster presentation, preclinical data demonstrating a unique binding mode of luxeptinib to wild type and C481S mutant BTK. Further, we presented that luxeptinib suppresses the BCR, AKT/PI3K, ERK and NFkB signaling pathways and exerts broader and far greater potency of direct cancer cell killing that ibrutinib against malignant bone marrow cells from patients with CLL, ALL and a host of other hematologic malignancies.

On December 3, 2018, we announced two separate poster presentations at the American Society of Hematology (“ASH”) Annual Meeting. The OHSU Knight Cancer Institute and Aptose presented data in one poster and the team at The University of MDACC presented data in a separate poster. These presentations highlighted several key findings. First, in collaboration with the MDACC, orally administered luxeptinib demonstrated efficacy in a PDX study in which the bone marrow cells from a patient with AML having dual ITD and D835 mutations in FLT3 were implanted into a mouse. The dual FLT3 mutant form of AML represents a very difficult-to-treat population that has shown resistance to other FLT3 inhibitors, and data from the PDX model suggest that luxeptinib may be useful in treating such patients. Secondly, Aptose presented high level data from preclinical GLP toxicology studies that demonstrate orally administered luxeptinib is a well-tolerated targeted molecule. Finally, in collaboration with the OHSU Knight Cancer Center, studies of luxeptinib on 124 samples of freshly isolated bone marrow from CLL patients demonstrated both broader and greater cell killing potency for luxeptinib than Ibrutinib.

On April 1, 2019, at the 2019 Annual Meeting of the AACR, Aptose, along with our collaborators at OHSU Knight Cancer Institute, presented data highlighting luxeptinib was more potent in killing AML patient-derived samples than other FLT3 inhibitors including midostaurin, sorafenib, sunitinib, dovitinib, quizartinib, crenolanib and gilteritinib. Luxeptinib was equally potent against cells from patients in the adverse, intermediate and favorable risk groups (2017 ELN risk stratification), and cells from patients with relapsed or transformed AML (World Health Organization classification) were as sensitive as those from patients with de novo AML. The data demonstrated potency on primary AML patient samples across all AML subgroups including relapsed/refractory/transformed AML and those with genetic abnormalities related to poor prognosis. While patient samples with FLT3-ITD mutations were expected to have greater sensitivity to luxeptinib, the most surprising correlation was the sensitivity of patient samples with IDH1 R132 mutations. The enhanced sensitivity of IDH-1 mutant AML to luxeptinib warrants investigation in the clinical setting. Moreover, in studies of luxeptinib on AML patient bone marrow samples, we demonstrated that mutations in p53, ASXL1 and NPM1 do not hinder the potency of luxeptinib.

On June 14, 2019, we presented new preclinical data for luxeptinib in a poster presentation at the 24th Congress of the EHA in Amsterdam, the Netherlands. The poster, CG-806, preclinical in vivo efficacy and safety profile as a pan-FLT3 / pan-BTK inhibitor, highlights the in vivo anti-leukemic efficacy of luxeptinib and its GLP toxicology and toxicokinetic profile. In a preclinical MV4-11 FLT3-ITD AML xenograft mouse model, luxeptinib suppressed leukemia growth at all doses tested throughout the 28-day period of dosing. In the mice treated with 100 mg/kg, 5 of 11 (45%) were cured through day 120, and in the 300 mg/kg group, 10 of 11 (91%) of the mice were cured. Retreating the “uncured’ mice in these two dose groups for an additional 28 days beginning on day 88 led to rapid and robust antitumor response in all retreated mice through day 120. In the “re-treated” mice, no drug resistance and no toxicities were observed. GLP 28-day toxicology and TK studies mice and dogs showed no adverse luxeptinib-related effects on body weight, ophthalmic, respiratory or neurological examinations, clinical pathology (coagulation, clinical chemistry, or urinalysis), organ weight or macroscopic evaluations. No luxeptinib-related cardiovascular effects were noted in the 28-day GLP toxicology study or in a separate preclinical cardiovascular safety study.

On October 24, 2019, we presented preclinical data in a poster presentation at the 5th International Conference on Acute Myeloid Leukemia “Molecular and Translational” Advances in Biology and Treatment in Estoril, Portugal. The poster, CG-806 Pan-FLT3/Pan-BTK Inhibitor Simultaneously Suppresses Multiple Oncogenic Signaling Pathways to Treat AML, highlighted that luxeptinib acts on large xenograft tumors with no evidence of drug resistance and with no observed toxicity, enhances killing of patient-derived AML and B-cell cancer cells when combined with venetoclax, and retains activity in patient-derived AML cells even when cells harbor mutations of FLT3, IDH-1, NPM1, ASXL1 or p53.

On December 8 and 9, 2019, we presented new preclinical data in two separate poster presentations at the 61st ASH Annual Meeting. On December 8, 2019, the poster CG-806, a First-in-Class Pan-FLT3/Pan-BTK Inhibitor, Exhibits Broad Signaling Inhibition in Chronic Lymphocytic Leukemia Cells compared luxeptinib and ibrutinib, the standard of care, on primary patient cells of CLL highlighting that CG-806 broadly inhibits B-cell receptor signaling in CLL cells, resulting in CLL cell apoptosis and reduced proliferation, luxeptinib is more potent than ibrutinib in inducing apoptosis of MEC1 CLL cells and, finally, luxeptinib targets elements of the CLL microenvironment, and thereby potentially targets pro-survival signals from the microenvironment. The poster presented on December 9, 2019 titled Synergistic Targeting of BTK and E-Selectin/CXCR4 in the Microenvironment of Mantle Cell Lymphomas, explored the effects of luxeptinib on cells of MCL, a rare subtype of aggressive B cell non Hodgkin lymphoma that is incurable with standard therapy, and investigated the molecular mechanisms of acquired resistance to treatment, highlighted that luxeptinib demonstrated superior anti-lymphoma effects compared with ibrutinib, exerting potent cell growth inhibitory effects on ibrutinib-resistant MCL cells, luxeptinib suppresses phospho-BTK, -Stat3, -AKT, -ERK, -Src, NF-kB, and the anti-apoptotic protein Mcl1, while upregulating p53, luxeptinib increased autophagy in MCL cells, which may be associated with resistance to luxeptinib-mediated apoptosis. Inhibition of autophagy re-sensitizes MCL cells to luxeptinib-induced apoptosis, luxeptinib treatment upregulates CXCR4/E-selectin levels in MCL cells and finally, combination of CXCR4/E-selectin antagonists with luxeptinib enhances luxeptinib-induced apoptotic killing of MCL cells in the presence of the tumor microenvironment. On December 7, 2019, Aptose also hosted a corporate event and clinical update, where the company’s management and invited Key Opinion Leaders highlighted some early clinical observations on safety, tolerability, pharmacokinetics, and activity, including. The discussion focused on key findings from dose levels one and two of luxeptinib in heavily pretreated R/R CLL patients, including: the clean safety profile to date, with no myelosuppression, drug-related adverse events or dose-limiting toxicity observed; meaningful oral absorption and predictable pharmacokinetic (“PK”) profile; evidence of target engagement manifesting as inhibition of Phospho-BTK, Phospho-SYK and Phospho-ERK in a plasma inhibitory assay (“PIA”) using plasma from the CLL patient on dose level two, and early evidence of clinical activity in the same patient manifesting as increase in peripheral blood lymphocytes (lymphocytosis), typically associated with BTK inhibition.

On April 27, 2020, we presented the early clinical data on luxeptinib at the AACR Virtual Annual Meeting I in lieu of the live oral presentation originally planned. A video summary of Abstract # 9967 - Early clinical findings from a Phase 1a/b dose escalation trial to evaluate the safety and tolerability of CG-806 in patients with relapsed or refractory CLL/SLL or non-Hodgkin’s lymphomas described the first-in-human tests of luxeptinib which are being carried out in a Phase 1a/b clinical study in patients with significant unmet needs including patients with relapsed or refractory CLL, SLL or NHL who had been failed by or been intolerant to two lines of established therapy. We noted that the second patient, treated at the 300 mg BID dose level, represented a classic CLL patient that developed a brisk lymphocytosis (evidence of BTK target engagement and evidence of pharmacologic activity), and that enrollment was continuing.

On June 12, 2020, we presented new clinical data on luxeptinib in a poster presentation at the 25th Congress of the EHA. The poster, Early Clinical Findings from a Phase 1 a/b Dose Escalation Trial to Evaluate the Safety and Tolerability of CG-806 in Patients with Relapsed or Refractory CLL/SLL or Non-Hodgkin’s Lymphomas (EHA2020 Abstract# EP711), reviewed luxeptinib data for eight patients (as of the data cut-off date on May 5, 2020) with relapsed or refractory CLL, SLL or NHL in the first in-human Phase 1a/b, open-label, single arm, multicenter dose-escalation clinical study. Data from the ongoing trial demonstrated that luxeptinib was well-tolerated in patients treated at 150 mg, 300 mg, 450 mg BID over multiple cycles, with no dose-limiting toxicities or serious adverse events observed, supporting continued dose escalation. Luxeptinib treatment achieved human steady state PK levels known to be effective in murine tumor models and led to complete inhibition of phospho-BTK and multiple CLL survival pathways. Luxeptinib treatment also led to lymphocytosis in both classic CLL patients entering study with elevated lymphocyte counts and led to complete inhibition of phospho-FLT3, suggesting that dose levels evaluated in this study may be therapeutic in patients with AML.

On June 22, 2020, we presented new preclinical data on luxeptinib in a poster presentation at the AACR Virtual Annual II 2020. The poster, CG-806, a First-in-Class FLT3/BTK Inhibitor, and Venetoclax Synergize to Inhibit Cell Proliferation and to Induce Apoptosis and Aggressive B-cell Lymphomas, illustrated how luxeptinib simultaneously inhibits the driver BCR pathway and PI3K/AKT, NFᴋB and MAPK-mediated rescue pathways to kill aggressive double-hit and double-expressor B-cell lymphoma cells. Overall, the presented work provided additional mechanistic evidence to support the clinical development of CG-806 as a single agent or in combination with venetoclax in patients with aggressive B-cell lymphomas harboring unfavorable BCL2/MYC/BCL6 translocations and / or overexpression.

APTO-253

Indication and Clinical Trials:

APTO-253, a small molecule inhibitor of MYC gene expression, is being evaluated in a Phase 1a/b clinical trial in patients with R/R AML and high-risk MDS. The multicenter, open-label, dose-escalation clinical trial is designed to assess the safety, tolerability, pharmacokinetics and pharmacodynamic responses and efficacy of APTO-253 as a single agent and determine the recommended Phase 2 dose. APTO-253 is being administered once weekly, over a 28-day cycle. The dose escalation stage of the study could potentially enroll up to 20 patients with R/R AML or high-risk MDS. The study is designed to then transition, as appropriate, to single-agent expansion cohorts in R/R AML and/or high-risk MDS.

As of the date of this report, we have multiple active sites recruiting patients in the dose escalation stage of the trial. As of the date of this report, we have completed enrollment and treatment of patients on the first, second, third, fourth, and fifth dose levels (20, 40, 66, 100, and 150 mg/m2, respectively). Under an FDA-approved accelerated titration protocol, only one patient was required at each of the first two dose levels, followed by three patients at each dose level thereafter. Aptose is currently enrolling patients in the sixth dose level (210 mg/m2) of APTO-253. During the second quarter of 2020, the FDA allowed an amendment for Aptose to initiate more aggressive dose escalations with APTO-253, provided the tolerability profile remains favorable. The first fivedosing cohorts have enrolled a mix of patients with AML and MDS. To date, we have observed reductions in MYC expression in peripheral blood mononuclear cells (PBMCs) from treated patients with AML and MDS, demonstrating MYC target engagement and mechanistic proof of concept.

Manufacturing:

We are continuing to manufacture additional drug substance and drug product for use in the ongoing trial.

We are exploring additional drug delivery methods for APTO-253 and plan to initiate additional non-clinical studies for solid tumor and hematologic cancer development. As preparing, submitting, and advancing applications for regulatory approval, developing drugs and drug product and clinical trials are sometimes complex, costly, and time-consuming processes, an estimate of the future costs is not reasonable at this time.

Preclinical and Clinical Updates:

Key presentations on APTO-253 at recent scientific forums are as follows: