Business	9 Months Ended
Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business	1. Business We are a commercial-stage biotechnology company focused on improving the lives of patients by developing best-in-class treatments to address some of the most important unmet patient needs. Our advanced science, patented technologies, and innovative approach to drug discovery and development have allowed us to create and commercialize a portfolio of products that aim to advance the standard of care for acute care and oncology patients. In August 2016, our first commercial product, SUSTOL (granisetron) extended-release injection (“SUSTOL”), was approved by the U.S. Food and Drug Administration (“FDA”). SUSTOL is indicated in combination with other antiemetics in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic chemotherapy (MEC) or anthracycline and cyclophosphamide (AC) combination chemotherapy regimens. SUSTOL is an extended-release, injectable 5-hydroxytryptamine type 3 receptor antagonist that utilizes our proprietary Biochronomer drug delivery technology to maintain therapeutic levels of granisetron for ≥5 days. We commenced commercial sales of SUSTOL in the U.S. in October 2016. In November 2017, our second commercial product, CINVANTI (aprepitant) injectable emulsion (“CINVANTI”), was approved by the FDA. In October 2019, the FDA approved our supplemental New Drug Application (“sNDA”) for CINVANTI to expand the indication and recommended dosage to include the 130 mg single-dose regimen for patients receiving moderately emetogenic cancer chemotherapy (“MEC”). CINVANTI, in combination with other antiemetic agents, is indicated in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy (HEC) including high-dose cisplatin as a single-dose regimen, delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy (MEC) as a single-dose regimen, and nausea and vomiting associated with initial and repeat courses of MEC as a 3-day regimen. CINVANTI is an intravenous (“IV”) formulation of aprepitant, a substance P/neurokinin-1 (“NK₁”) receptor antagonist. We commenced commercial sales of CINVANTI in the U.S. in January 2018. In February 2019, the FDA approved our sNDA for CINVANTI, for IV use, which expanded the administration of CINVANTI beyond the initially approved administration method (a 30-minute IV infusion) to include a 2-minute IV injection. In May 2021, our third commercial product, ZYNRELEF (bupivacaine and meloxicam) extended-release solution (“ZYNRELEF”), was approved by the FDA. ZYNRELEF is currently indicated for use in adults for soft tissue or periarticular instillation to produce postsurgical analgesia for up to 72 hours after bunionectomy, open inguinal herniorrhaphy and total knee arthroplasty. ZYNRELEF is a dual-acting local anesthetic that delivers a fixed-dose combination of the local anesthetic bupivacaine and a low dose of nonsteroidal anti-inflammatory drug meloxicam. ZYNRELEF is the first and only modified-release local anesthetic to be classified by the FDA as an extended-release product because ZYNRELEF demonstrated in Phase 3 studies significantly reduced pain and significantly increased proportion of patients requiring no opioids through the first 72 hours following surgery compared to bupivacaine solution, the current standard-of-care local anesthetic for postoperative pain control. We commenced commercial sales of ZYNRELEF in the U.S. in July 2021. At a Type C meeting with the FDA, following the ZYNRELEF New Drug Application (“NDA”) approval, we aligned with the FDA on the content of an sNDA for proposed expansion of the ZYNRELEF indication statement to include foot and ankle, small–to–medium open abdominal, and lower extremity total joint arthroplasty surgical procedures without the need for additional clinical studies. The sNDA is based on the consistent safety, efficacy and pharmacokinetic data from previously completed clinical trials and was submitted to the FDA in late September 2021. We also aligned with the FDA on the data needed to support a future sNDA to further expand the ZYNRELEF indication statement to broadly include soft tissue and orthopedic surgical procedures with pharmacodynamic, pharmacokinetic and safety data from a limited number of additional procedures. The studies in these additional surgeries are already in progress with the plan to submit the next sNDA in the second half of 2022. Heron recently received FDA approval in less than 4 months of a manufacturing supplement to the NDA for ZYNRELEF to add a large-scale secondary supplier of our proprietary polymer, which will allow for the manufacturing of millions of doses of ZYNRELEF annually at a significantly reduced cost of product sales. In September 2020, ZYNRELEFwas granted a marketing authorization by the European Commission. As of January 1, 2021, ZYNRELEF is approved in 31 European countries including the countries of the European Union and European Economic Area and the United Kingdom. ZYNRELEF is indicated for the treatment of somatic postoperative pain from small- to medium-sized surgical wounds in adults. As we build large-scale manufacturing capacity to meet the anticipated commercial demand in the U.S. and the rest of the world, we are developing a coordinated global marketing strategy. At this time, we anticipate making ZYNRELEF available to patients in Europe in late 2022. HTX-011 (ZYNRELEF in the U.S. and Europe) is an investigational agent in Canada. Our New Drug Submission for HTX-011 for the management of postoperative pain was accepted by Health Canada in November 2019. In April 2021, we responded to a list of questions received from Health Canada, and we anticipate up to a 300-day review period following screening of our responses. HTX-034, our next-generation product candidate for postoperative pain management, is an investigational non-opioid, fixed-dose combination, extended‑release solution of the local anesthetic bupivacaine, the nonsteroidal anti-inflammatory drug meloxicam and aprepitant that further potentiates the activity of bupivacaine. HTX-034 is formulated in the same proprietary polymer as ZYNRELEF. By combining two different mechanisms that each enhance the activity of the local anesthetic bupivacaine, HTX-034 is designed to provide superior and prolonged analgesia. Local administration of HTX-034 in a validated preclinical postoperative pain model resulted in sustained analgesia for 7 days. In May 2020, we initiated a Phase 1b/2 clinical study in patients undergoing bunionectomy of HTX-034. In the Phase 1b portion of this Phase 1b/2 double-blind, randomized, active-controlled, dose-escalation study in 33 patients undergoing bunionectomy, the reduction in pain intensity observed was greater with the lowest dose of HTX-034 evaluated (containing 21.7 mg of bupivacaine plus meloxicam and aprepitant) than with the bupivacaine 50 mg solution through 96 hours. In addition, 45.5% of HTX-034 patients remained opioid-free through Day 15 with median opioid consumption of 2.5 milligram morphine equivalents (same as one 5 mg oxycodone pill) through 72-hours, a 71% reduction compared to bupivacaine solution. We initiated the expanded Phase 2 portion of the study for HTX-034 in the first quarter of 2021. We have temporarily postponed work on HTX-034 while we work with the FDA on expanding the indication statement for ZYNRELEF. We will re-evaluate the HTX-034 program after approval of our first ZYNRELEF sNDA. HTX-019 is an investigational agent for the prevention of postoperative nausea and vomiting (“PONV”). HTX-019 is an IV injectable emulsion formulation designed to directly deliver aprepitant, the active ingredient in EMEND^® (aprepitant) capsules, which is the only NK₁ receptor antagonist approved in the U.S. for the prevention of PONV in adults. The FDA-approved dose of oral EMEND is 40 mg for PONV, which is given within 3 hours prior to induction of anesthesia for surgery. An Investigational New Drug application for HTX-019 for PONV was approved by the FDA in late September 2020. In a Phase 1 clinical trial, 32 mg of HTX-019 as a 30-second IV injection was demonstrated to be bioequivalent to oral aprepitant 40 mg. A Pre-NDA meeting with the FDA was held in August 2021 and the HTX-019 NDA for prevention of PONV in adults is on track for filing in the fourth quarter of 2021. As of September 30, 2021 we had $202.8 million in cash, cash equivalents and short-term investments. We have incurred significant operating losses and negative cash flows from operations. Management believes that the Company’s existing cash, cash equivalents and short-term investments will be sufficient to meet the Company’s anticipated cash requirements for at least one year from the date this Quarterly Report on Form 10-Q is filed with the U.S. Securities and Exchange Commission (“SEC”).

Business

9 Months Ended

Sep. 30, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Business

We are a commercial-stage biotechnology company focused on improving the lives of patients by developing best-in-class treatments to address some of the most important unmet patient needs. Our advanced science, patented technologies, and innovative approach to drug discovery and development have allowed us to create and commercialize a portfolio of products that aim to advance the standard of care for acute care and oncology patients.

In August 2016, our first commercial product, SUSTOL (granisetron) extended-release injection (“SUSTOL”), was approved by the U.S. Food and Drug Administration (“FDA”). SUSTOL is indicated in combination with other antiemetics in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic chemotherapy (MEC) or anthracycline and cyclophosphamide (AC) combination chemotherapy regimens. SUSTOL is an extended-release, injectable 5-hydroxytryptamine type 3 receptor antagonist that utilizes our proprietary Biochronomer drug delivery technology to maintain therapeutic levels of granisetron for ≥5 days. We commenced commercial sales of SUSTOL in the U.S. in October 2016.

In November 2017, our second commercial product, CINVANTI (aprepitant) injectable emulsion (“CINVANTI”), was approved by the FDA. In October 2019, the FDA approved our supplemental New Drug Application (“sNDA”) for CINVANTI to expand the indication and recommended dosage to include the 130 mg single-dose regimen for patients receiving moderately emetogenic cancer chemotherapy (“MEC”). CINVANTI, in combination with other antiemetic agents, is indicated in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy (HEC) including high-dose cisplatin as a single-dose regimen, delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy (MEC) as a single-dose regimen, and nausea and vomiting associated with initial and repeat courses of MEC as a 3-day regimen. CINVANTI is an intravenous (“IV”) formulation of aprepitant, a substance P/neurokinin-1 (“NK₁”) receptor antagonist. We commenced commercial sales of CINVANTI in the U.S. in January 2018. In February 2019, the FDA approved our sNDA for CINVANTI, for IV use, which expanded the administration of CINVANTI beyond the initially approved administration method (a 30-minute IV infusion) to include a 2-minute IV injection.

In May 2021, our third commercial product, ZYNRELEF (bupivacaine and meloxicam) extended-release solution (“ZYNRELEF”), was approved by the FDA. ZYNRELEF is currently indicated for use in adults for soft tissue or periarticular instillation to produce postsurgical analgesia for up to 72 hours after bunionectomy, open inguinal herniorrhaphy and total knee arthroplasty. ZYNRELEF is a dual-acting local anesthetic that delivers a fixed-dose combination of the local anesthetic bupivacaine and a low dose of nonsteroidal anti-inflammatory drug meloxicam. ZYNRELEF is the first and only modified-release local anesthetic to be classified by the FDA as an extended-release product because ZYNRELEF demonstrated in Phase 3 studies significantly reduced pain and significantly increased proportion of patients requiring no opioids through the first 72 hours following surgery compared to bupivacaine solution, the current standard-of-care local anesthetic for postoperative pain control. We commenced commercial sales of ZYNRELEF in the U.S. in July 2021.

At a Type C meeting with the FDA, following the ZYNRELEF New Drug Application (“NDA”) approval, we aligned with the FDA on the content of an sNDA for proposed expansion of the ZYNRELEF indication statement to include foot and ankle, small–to–medium open abdominal, and lower extremity total joint arthroplasty surgical procedures without the need for additional clinical studies. The sNDA is based on the consistent safety, efficacy and pharmacokinetic data from previously completed clinical trials and was submitted to the FDA in late September 2021. We also aligned with the FDA on the data needed to support a future sNDA to further expand the ZYNRELEF indication statement to broadly include soft tissue and orthopedic surgical procedures with pharmacodynamic, pharmacokinetic and safety data from a limited number of additional procedures. The studies in these additional surgeries are already in progress with the plan to submit the next sNDA in the second half of 2022.

Heron recently received FDA approval in less than 4 months of a manufacturing supplement to the NDA for ZYNRELEF to add a large-scale secondary supplier of our proprietary polymer, which will allow for the manufacturing of millions of doses of ZYNRELEF annually at a significantly reduced cost of product sales.

In September 2020, ZYNRELEFwas granted a marketing authorization by the European Commission. As of January 1, 2021, ZYNRELEF is approved in 31 European countries including the countries of the European Union and European Economic Area and the United Kingdom. ZYNRELEF is indicated for the treatment of somatic postoperative pain from small- to medium-sized surgical wounds in adults. As we build large-scale manufacturing capacity to meet the anticipated commercial demand in the U.S. and the rest of the world, we are developing a coordinated global marketing strategy. At this time, we anticipate making ZYNRELEF available to patients in Europe in late 2022.

HTX-011 (ZYNRELEF in the U.S. and Europe) is an investigational agent in Canada. Our New Drug Submission for HTX-011 for the management of postoperative pain was accepted by Health Canada in November 2019. In April 2021, we responded to a list of questions received from Health Canada, and we anticipate up to a 300-day review period following screening of our responses.

HTX-034, our next-generation product candidate for postoperative pain management, is an investigational non-opioid, fixed-dose combination, extended‑release solution of the local anesthetic bupivacaine, the nonsteroidal anti-inflammatory drug meloxicam and aprepitant that further potentiates the activity of bupivacaine. HTX-034 is formulated in the same proprietary polymer as ZYNRELEF. By combining two different mechanisms that each enhance the activity of the local anesthetic bupivacaine, HTX-034 is designed to provide superior and prolonged analgesia. Local administration of HTX-034 in a validated preclinical postoperative pain model resulted in sustained analgesia for 7 days. In May 2020, we initiated a Phase 1b/2 clinical study in patients undergoing bunionectomy of HTX-034. In the Phase 1b portion of this Phase 1b/2 double-blind, randomized, active-controlled, dose-escalation study in 33 patients undergoing bunionectomy, the reduction in pain intensity observed was greater with the lowest dose of HTX-034 evaluated (containing 21.7 mg of bupivacaine plus meloxicam and aprepitant) than with the bupivacaine 50 mg solution through 96 hours. In addition, 45.5% of HTX-034 patients remained opioid-free through Day 15 with median opioid consumption of 2.5 milligram morphine equivalents (same as one 5 mg oxycodone pill) through 72-hours, a 71% reduction compared to bupivacaine solution. We initiated the expanded Phase 2 portion of the study for HTX-034 in the first quarter of 2021. We have temporarily postponed work on HTX-034 while we work with the FDA on expanding the indication statement for ZYNRELEF. We will re-evaluate the HTX-034 program after approval of our first ZYNRELEF sNDA.

HTX-019 is an investigational agent for the prevention of postoperative nausea and vomiting (“PONV”). HTX-019 is an IV injectable emulsion formulation designed to directly deliver aprepitant, the active ingredient in EMEND^® (aprepitant) capsules, which is the only NK₁ receptor antagonist approved in the U.S. for the prevention of PONV in adults. The FDA-approved dose of oral EMEND is 40 mg for PONV, which is given within 3 hours prior to induction of anesthesia for surgery. An Investigational New Drug application for HTX-019 for PONV was approved by the FDA in late September 2020. In a Phase 1 clinical trial, 32 mg of HTX-019 as a 30-second IV injection was demonstrated to be bioequivalent to oral aprepitant 40 mg. A Pre-NDA meeting with the FDA was held in August 2021 and the HTX-019 NDA for prevention of PONV in adults is on track for filing in the fourth quarter of 2021.

As of September 30, 2021 we had $202.8 million in cash, cash equivalents and short-term investments. We have incurred significant operating losses and negative cash flows from operations. Management believes that the Company’s existing cash, cash equivalents and short-term investments will be sufficient to meet the Company’s anticipated cash requirements for at least one year from the date this Quarterly Report on Form 10-Q is filed with the U.S. Securities and Exchange Commission (“SEC”).