Company and Nature of Business	3 Months Ended
Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company and Nature of Business	1. Company and Nature of Business Organization and Description of Business Athenex, Inc. and subsidiaries (the “Company” or “Athenex”), originally under the name Kinex Pharmaceuticals LLC (“Kinex”), formed in November 2003, commenced operations on February 5, 2004, and operated as a limited liability company until it was incorporated in the State of Delaware under the name Kinex Pharmaceuticals, Inc. on December 31, 2012. The Company changed its name to Athenex, Inc. on August 26, 2015. Athenex is a biopharmaceutical company dedicated to becoming a leader in the discovery, development, and commercialization of next generation drugs for the treatment of cancer. The Company’s mission is to improve the lives of cancer patients by creating more effective, safer and tolerable treatments. The Company has assembled a strong and experienced leadership team and has established operations across the pharmaceutical value chain to execute our goal of becoming a leader in bringing innovative cancer treatments to the market and improving health outcomes. The Company is organized around three operating segments: (1) its Oncology Innovation Platform, dedicated to the research and development of our proprietary drugs; (2) its Commercial Platform, focused on the sales and marketing of our specialty drugs and the market development of our proprietary drugs; and (3) its Global Supply Chain Platform, dedicated to providing a stable and efficient supply of APIs for our clinical and commercial efforts. The Company’s current clinical pipeline in the Oncology Innovation Platform is derived from four different proprietary technologies: (1) Orascovery, based on a P-glycoprotein (“P-gp”) pump inhibitor, (2) Src Kinase Inhibition, (3) Cell Therapy, and (4) Arginine Deprivation Therapy. The Company is primarily engaged in conducting research and development activities through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting preclinical and clinical testing, identifying and evaluating additional drug candidates for potential in-licensing or acquisition, and raising capital to support development and commercialization activities. The Company also conducts commercial sales of specialty products through its wholly owned subsidiary, Athenex Pharmaceutical Division (“APD”), and 503B products through its wholly owned subsidiary, Athenex Pharma Solutions (“APS”). Significant Risks and Uncertainties The Company has incurred operating losses since its inception and, as a result, as of March 31, 2021 and December 31, 2020 had an accumulated deficit of $738.7 million and $713.6 million, respectively. As of March 31, 2021, the Company had cash and cash equivalents of $48.0 million, restricted cash of $16.5 million, and short-term investments of $123.2 million. The Company believes that the existing cash and cash equivalents, restricted cash, and short-term investments will enable us to meet our current operational liquidity needs and fund operations into the second half of 2022. The Company has based these estimates on assumptions that may prove to be wrong, and it could spend the available financial resources much faster than expected and need to raise additional funds sooner than anticipated. Operations have been funded primarily through the sale of common stock, senior secured loans, and to a lesser extent, from convertible bond financing, revenue, and grant funding. The Company will require significant additional funds to conduct clinical trials and to fund its commercialization and manufacturing operations. There can be no assurance that this funding will be available for our use when needed, or at all. If adequate funds are not available, the Company may be required to delay, modify, or terminate its research and development programs or reduce its planned commercialization efforts. Further, if the Company is unable to obtain additional financing, the Company will need to reevaluate future operating plans. Although the Company plans to raise additional funds, these plans are subject to market conditions which are outside of its control and therefore cannot be deemed to be probable. In February 2021, the Company received a Complete Response Letter (“CRL”) from the U.S. Food and Drug Administration (“FDA”) regarding the Company’s New Drug Application (“NDA”) for oral paclitaxel and encequidar (“Oral Paclitaxel”) for the treatment of metastatic breast cancer. The FDA issues a CRL to indicate that the review cycle for an application is complete and that the application is not ready for approval in its present form. In the CRL, the FDA indicated its concern of safety risk to patients in terms of an increase in neutropenia-related sequelae on the Oral Paclitaxel arm compared with the IV paclitaxel arm in the Phase III study. The FDA also expressed concerns regarding the uncertainty over the results of the primary endpoint of objective response rate (ORR) at week 19 conducted by blinded independent central review (“BICR”). The FDA stated that the BICR reconciliation and re-read process may have introduced unmeasured bias and influence on the BICR. The FDA recommended that Athenex conduct a new adequate and well-conducted clinical trial in a patient population with metastatic breast cancer representative of the population in the U.S. The FDA determined that additional risk mitigation strategies to improve toxicity, which may involve dose optimization as well as, or in addition to, exclusion of patients deemed to be at higher risk of toxicity, are required to support potential approval of the NDA. We are working to consider the appropriate next steps in the development of Oral Paclitaxel. We have been preparing for and plan to request a meeting with the FDA and plan to engage in a dialogue on the design and scope of a clinical trial to address the FDA’s requirements and align on the next steps required to obtain approval. The Company’s ability to potentially commercialize Oral Paclitaxel, and the timing of potential commercialization, is dependent on the discussion with the agency, the Company’s resubmission of its NDA, ultimate FDA approval, and potentially additional capital. The Company is subject to a number of risks similar to other biopharmaceutical companies, including, but not limited to, the lack of available capital; possible failure of preclinical testing or clinical trials, inability to obtain regulatory approval of product candidates; competitors developing new technological innovations; unsuccessful commercialization strategy and launch plans for its proprietary drug candidates; risks inherent in litigation, including purported class actions; market acceptance of the Company’s products; and protection of proprietary technology. If the Company or its partners do not successfully commercialize any of the Company’s product candidates, it will be unable to generate sufficient product revenue and might not, if ever, achieve profitability and positive cash flow.

Company and Nature of Business

3 Months Ended

Mar. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Company and Nature of Business

Organization and Description of Business

Athenex, Inc. and subsidiaries (the “Company” or “Athenex”), originally under the name Kinex Pharmaceuticals LLC (“Kinex”), formed in November 2003, commenced operations on February 5, 2004, and operated as a limited liability company until it was incorporated in the State of Delaware under the name Kinex Pharmaceuticals, Inc. on December 31, 2012. The Company changed its name to Athenex, Inc. on August 26, 2015.

Athenex is a biopharmaceutical company dedicated to becoming a leader in the discovery, development, and commercialization of next generation drugs for the treatment of cancer. The Company’s mission is to improve the lives of cancer patients by creating more effective, safer and tolerable treatments. The Company has assembled a strong and experienced leadership team and has established operations across the pharmaceutical value chain to execute our goal of becoming a leader in bringing innovative cancer treatments to the market and improving health outcomes.

The Company is organized around three operating segments: (1) its Oncology Innovation Platform, dedicated to the research and development of our proprietary drugs; (2) its Commercial Platform, focused on the sales and marketing of our specialty drugs and the market development of our proprietary drugs; and (3) its Global Supply Chain Platform, dedicated to providing a stable and efficient supply of APIs for our clinical and commercial efforts. The Company’s current clinical pipeline in the Oncology Innovation Platform is derived from four different proprietary technologies: (1) Orascovery, based on a P-glycoprotein (“P-gp”) pump inhibitor, (2) Src Kinase Inhibition, (3) Cell Therapy, and (4) Arginine Deprivation Therapy.

The Company is primarily engaged in conducting research and development activities through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting preclinical and clinical testing, identifying and evaluating additional drug candidates for potential in-licensing or acquisition, and raising capital to support development and commercialization activities. The Company also conducts commercial sales of specialty products through its wholly owned subsidiary, Athenex Pharmaceutical Division (“APD”), and 503B products through its wholly owned subsidiary, Athenex Pharma Solutions (“APS”).

Significant Risks and Uncertainties

The Company has incurred operating losses since its inception and, as a result, as of March 31, 2021 and December 31, 2020 had an accumulated deficit of $738.7 million and $713.6 million, respectively. As of March 31, 2021, the Company had cash and cash equivalents of $48.0 million, restricted cash of $16.5 million, and short-term investments of $123.2 million.

The Company believes that the existing cash and cash equivalents, restricted cash, and short-term investments will enable us to meet our current operational liquidity needs and fund operations into the second half of 2022. The Company has based these estimates on assumptions that may prove to be wrong, and it could spend the available financial resources much faster than expected and need to raise additional funds sooner than anticipated. Operations have been funded primarily through the sale of common stock, senior secured loans, and to a lesser extent, from convertible bond financing, revenue, and grant funding. The Company will require significant additional funds to conduct clinical trials and to fund its commercialization and manufacturing operations. There can be no assurance that this funding will be available for our use when needed, or at all. If adequate funds are not available, the Company may be required to delay, modify, or terminate its research and development programs or reduce its planned commercialization efforts. Further, if the Company is unable to obtain additional financing, the Company will need to reevaluate future operating plans. Although the Company plans to raise additional funds, these plans are subject to market conditions which are outside of its control and therefore cannot be deemed to be probable.

In February 2021, the Company received a Complete Response Letter (“CRL”) from the U.S. Food and Drug Administration (“FDA”) regarding the Company’s New Drug Application (“NDA”) for oral paclitaxel and encequidar (“Oral Paclitaxel”) for the treatment of metastatic breast cancer. The FDA issues a CRL to indicate that the review cycle for an application is complete and that the application is not ready for approval in its present form. In the CRL, the FDA indicated its concern of safety risk to patients in terms of an increase in neutropenia-related sequelae on the Oral Paclitaxel arm compared with the IV paclitaxel arm in the Phase III study. The FDA also expressed concerns regarding the uncertainty over the results of the primary endpoint of objective response rate (ORR) at week 19 conducted by blinded independent central review (“BICR”). The FDA stated that the BICR reconciliation and re-read process may have introduced unmeasured bias and influence on the BICR. The FDA recommended that Athenex conduct a new adequate and well-conducted clinical trial in a patient population with metastatic breast cancer representative of the population in the U.S. The FDA determined that additional risk mitigation strategies to improve toxicity, which may involve dose optimization as well as, or in addition to, exclusion of patients deemed to be at higher risk of toxicity, are required to support potential approval of the NDA. We are working to consider the appropriate next steps in the development of Oral Paclitaxel. We have been preparing for and plan to request a meeting

with the FDA and plan to engage in a dialogue on the design and scope of a clinical trial to address the FDA’s requirements and align on the next steps required to obtain approval. The Company’s ability to potentially commercialize Oral Paclitaxel, and the timing of potential commercialization, is dependent on the discussion with the agency, the Company’s resubmission of its NDA, ultimate FDA approval, and potentially additional capital.

The Company is subject to a number of risks similar to other biopharmaceutical companies, including, but not limited to, the lack of available capital; possible failure of preclinical testing or clinical trials, inability to obtain regulatory approval of product candidates; competitors developing new technological innovations; unsuccessful commercialization strategy and launch plans for its proprietary drug candidates; risks inherent in litigation, including purported class actions; market acceptance of the Company’s products; and protection of proprietary technology. If the Company or its partners do not successfully commercialize any of the Company’s product candidates, it will be unable to generate sufficient product revenue and might not, if ever, achieve profitability and positive cash flow.