First U.S. Patient Dosed in BiPASS: Phase 3 Prostate Cancer Diagnosis Study

Rhea-AI Summary

Telix (TLX) announced the first U.S. patient has been dosed in BiPASS, a Phase 3 trial evaluating Illuccix and Gozellix 68Ga-PSMA-11 PET agents in the pre-biopsy prostate cancer diagnosis setting. The prospective, open-label study will enroll 250 patients across the U.S. and Australia and is designed to support marketing authorization for 68Ga-PSMA-PET in the pre-biopsy pathway. The trial will assess whether combining MRI with 68Ga-PSMA-11 PET improves diagnostic accuracy, reduces unnecessary biopsies (up to 75% of U.S. biopsies are reportedly negative), and enables better patient stratification and biopsy precision if objectives are met.

Positive

• First U.S. patient dosed in Phase 3 BiPASS trial
• Study will enroll 250 patients across the U.S. and Australia
• Trial seeks marketing authorization for 68Ga-PSMA-PET in pre-biopsy setting
• Targets reduction of unnecessary biopsies where up to 75% are negative

Negative

• Clinical benefit depends on meeting primary endpoints; outcomes remain uncertain

News Market Reaction

+4.44%

1 alert

+4.44% News Effect

+$110M Valuation Impact

$2.60B Market Cap

0.9x Rel. Volume

On the day this news was published, TLX gained 4.44%, reflecting a moderate positive market reaction. This price movement added approximately $110M to the company's valuation, bringing the market cap to $2.60B at that time.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Planned enrollment: 250 patients Annual prostate biopsies: More than one million Negative biopsy rate: Up to 75% +1 more

4 metrics

Planned enrollment 250 patients BiPASS Phase 3 trial across U.S. and Australia

Annual prostate biopsies More than one million Estimated number performed annually in the U.S.

Negative biopsy rate Up to 75% Share of U.S. prostate biopsies reported as negative

Biopsy refusal rate One in four patients Patients declining a recommended prostate biopsy in the U.S.

Market Reality Check

Price: $7.61 Vol: Volume 217,531 vs 20-day ...

normal vol

$7.61 Last Close

Volume Volume 217,531 vs 20-day average 200,946 (relative volume 1.08). normal

Technical Price $7.43 is trading below the 200-day MA at $12.58, near the 52-week low of $7.31 and well below the 52-week high of $30.36.

Peers on Argus

TLX fell 2.49% while peers showed mixed moves: RARE -1.55%, LGND -0.75%, MLTX -0...

TLX fell 2.49% while peers showed mixed moves: RARE -1.55%, LGND -0.75%, MLTX -0.79%, ZLAB -2.18%, and APLS up 0.29%. With no peers in the momentum scanner and no same-day peer headlines, the move appears more stock-specific than sector-driven.

Historical Context

5 past events · Latest: Jan 08 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Jan 08	Conference presentation	Positive	+1.7%	Announcement of JPM Healthcare Conference presentation and upcoming Q4 2025 release.
Dec 21	Clinical data update	Positive	+3.2%	Illuccix Phase 3 China success and NDA plans plus CDx FDA resubmissions.
Dec 10	Strategic collaboration	Positive	+3.1%	Theranostics-EBRT clinical collaboration with Varian focused on PSMA-PET imaging.
Nov 19	Clinical data update	Positive	-1.5%	ZIRCON-X data showing TLX250-CDx changed management in many renal mass patients.
Nov 05	Investor conferences	Neutral	+0.1%	Planned participation in UBS and Jefferies global healthcare conferences.

Pattern Detected

Recent Telix news, especially clinical and strategic updates, has usually aligned with modestly positive price reactions, though there has been at least one divergence where positive data coincided with a price decline.

Recent Company History

Over the past few months, Telix has reported several pipeline and partnership milestones. A Dec 21 clinical portfolio update highlighting Illuccix Phase 3 success in China and regulatory progress for Pixclara and Zircaix saw a 3.21% gain. A Dec 10 theranostics-EBRT collaboration with Varian and a Nov 19 ZIRCON-X analysis on TLX250‑CDx each underscored Telix’s imaging and theranostics strategy, though the latter drew a -1.53% move. Conference and JPM presentation notices generated smaller, generally positive reactions.

Market Pulse Summary

This announcement advances the BiPASS Phase 3 trial by dosing the first U.S. patient and targeting 2...

Analysis

This announcement advances the BiPASS Phase 3 trial by dosing the first U.S. patient and targeting 250 enrollees across the U.S. and Australia. It highlights a large addressable pool of more than one million prostate biopsies annually, of which up to 75% are negative. In context of Telix’s recent positive Phase 3 data and strategic collaborations, investors may watch for recruitment progress, diagnostic accuracy results, and any evidence of reduced unnecessary biopsies.

Key Terms

phase 3, psma-pet, 68ga-psma-pet, pet imaging, +4 more

8 terms

phase 3 medical

"a Phase 3 trial to evaluate the use of Telix’s commercial PSMA-PET1"

Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.

psma-pet medical

"evaluate the use of Telix’s commercial PSMA-PET1 imaging agents, Illuccix"

A PSMA-PET scan is a medical imaging test that uses a tiny radioactive tracer that sticks to a protein commonly found on prostate cancer cells, allowing a PET scanner to highlight tumors and metastases like a GPS map for cancer. It matters to investors because it can change how accurately disease is detected and staged, influence treatment choices, and drive demand, reimbursement and sales for imaging agents, scanners and related services.

68ga-psma-pet medical

"BiPASS™ is the first study designed to gain marketing authorization for 68Ga-PSMA-PET2 imaging"

A 68Ga-PSMA-PET is a medical imaging test that uses a tiny amount of radioactive gallium-68 attached to a molecule that seeks out PSMA, a marker often found on prostate cancer cells; the scan acts like a specialized camera that lights up cancer locations inside the body. For investors, it matters because use of this diagnostic changes how patients are staged and treated, drives demand for imaging agents, scanners and related services, and can affect clinical trial design and regulatory decisions tied to oncology products.

pet imaging medical

"Illuccix/Gozellix 68Ga-PSMA-11 PET can improve diagnostic accuracy"

PET imaging is a noninvasive medical scan that works like a molecular camera, using tiny radioactive tracers to reveal biological activity inside the body—for example metabolism, blood flow, or the presence of specific proteins. It matters to investors because PET results guide diagnosis, show whether a drug reaches its intended target and how patients respond, and therefore affect clinical trial success, regulatory approval, reimbursement decisions and demand for scanners, tracers and related services.

mri medical

"determine whether combining MRI3 with Illuccix/Gozellix 68Ga-PSMA-11 PET"

Magnetic resonance imaging (MRI) is a medical scan that uses magnetic fields and radio waves to create detailed pictures of the inside of the body, like a high-resolution camera for tissues and organs. Investors care because MRI drives demand for imaging machines, hospital services, diagnostics and can be central to clinical trial results and regulatory decisions—changes in MRI use or technology can affect revenue, capital spending and reimbursement in healthcare and medical device markets.

psa medical

"Men with elevated PSA4 often proceed from an inconclusive MRI"

Prostate-specific antigen (PSA) is a protein produced by prostate tissue and measured in blood to help detect and monitor prostate conditions, including prostate cancer and benign enlargement. For investors, changes in PSA levels reported in clinical studies or regulatory filings can signal how well a drug or diagnostic test is working, similar to how a gauge on a dashboard indicates the health of a machine and can affect a company’s valuation and regulatory outlook.

biopsy medical

"Men with elevated PSA4 often proceed from an inconclusive MRI to template prostate biopsy."

A biopsy is a medical procedure that removes a small piece of tissue or cells so a doctor can examine them under a microscope to see if disease, such as cancer or an infection, is present. For investors, biopsy results can change the outlook for drugs, diagnostics and medical devices—think of it like sampling a bite of food to decide whether the whole dish is safe; positive or negative findings can affect clinical trial success, approval chances, market demand and reimbursement decisions.

radiopharmacies medical

"The dose was administered ... and supplied by RLS Radiopharmacies."

Radiopharmacies are specialized pharmacies that prepare, test and dispense medicines containing short-lived radioactive atoms used for imaging scans and certain cancer treatments. Think of them as a time-sensitive deli that makes and delivers fresh, regulated products to hospitals and clinics on a tight schedule; disruption or quality issues can quickly halt patient care. For investors, radiopharmacy capacity, regulation, and supply reliability affect revenue, operational risk and the commercial success of diagnostic and therapeutic drugs.

AI-generated analysis. Not financial advice.

MELBOURNE, Australia, Jan. 17, 2026 (GLOBE NEWSWIRE) -- Telix Pharmaceuticals Limited (ASX: TLX, NASDAQ: TLX, “Telix”) today announces that the first patient in the United States (U.S.) has been dosed in BiPASS™ (Biopsy of the Prostate Avoidance Stratification Study), a Phase 3 trial to evaluate the use of Telix’s commercial PSMA-PET¹ imaging agents, Illuccix® (kit for the preparation of gallium Ga 68 gozetotide injection) and Gozellix® (kit for the preparation of gallium Ga 68 gozetotide injection) in the initial prostate cancer diagnosis setting. The dose was administered under the supervision of Dr. Brian Mazzarella at Urology Austin and supplied by RLS Radiopharmacies.

BiPASS™ is the first study designed to gain marketing authorization for ⁶⁸Ga-PSMA-PET² imaging in the pre-biopsy setting. The prospective, open-label Phase 3 trial will enroll 250 patients across sites in the U.S. and Australia. The study aims to determine whether combining MRI³ with Illuccix/Gozellix ⁶⁸Ga-PSMA-11 PET can improve diagnostic accuracy and reduce unnecessary biopsies compared to current standard practice. Men with elevated PSA⁴ often proceed from an inconclusive MRI to template prostate biopsy. This procedure is stressful and unpleasant, can lead to complications⁵ and frequently proves to be of no benefit to the patient⁶.

In the U.S., more than one million prostate biopsies are performed annually, yet up to 75% are negative⁶, and one in four patients declines the physician recommendation of receiving a biopsy⁷. The objective of BiPASS™ is to demonstrate improved lesion detection and patient stratification by integrating non-invasive molecular Illuccix/Gozellix ⁶⁸Ga-PSMA-11 PET imaging early in the diagnostic pathway, to enable biopsy de-escalation or, alternatively, greater biopsy precision when administered.

If the BiPASS™ study achieves its primary objectives, it could lead to a reduction in unnecessary biopsies, improved patient experience, and a significant expansion of access to precision imaging for patients with suspected prostate cancer, potentially increasing the use of ⁶⁸Ga-PSMA-11 PET in a large new patient population.

Dr. Mazzarella, Vice President of Research for Urology America, said, “We’re excited to participate in the BiPASS trial at Urology Austin, which brings together promising technologies and emerging trends in patient care. If BiPASS is successful in meeting its primary endpoint, it could eliminate the need for biopsy—reducing risks, side effects, and costs—and improve decision-making for providers and patients.”

Kevin Richardson, Chief Executive Officer, Telix Precision Medicine, added, “Illuccix and Gozellix are already transforming how clinicians treat and manage prostate cancer. By initiating this trial, we are reinforcing Telix’s commitment to patient centricity, clinical innovation, and industry leadership—with the goal of eliminating invasive biopsy.”

About BiPASS™

BiPASS™ (ClinicalTrials.gov ID: NCT07052214) leverages promising clinical findings from the PRIMARY⁸ and PRIMARY2⁹ studies, which demonstrated that MRI combined with ⁶⁸Ga-PSMA-11 PET can better define or rule out prostate cancer and guide active surveillance before invasive biopsy. Professor Louise Emmett, Principal Investigator for PRIMARY, serves on the BiPASS™ Steering Committee and as an Investigator on the study.

About Illuccix® (kit for the preparation of gallium Ga 68 gozetotide injection)

Illuccix, after radiolabeling with ⁶⁸Ga, is indicated for PET scanning of PSMA positive lesions in men with prostate cancer who have suspected metastasis and are candidates for initial definitive therapy, those with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level, and for selection of patients who are indicated for PSMA-directed therapy as described in the prescribing information of the therapeutic products.

IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS

Risk for Misinterpretation
Image interpretation errors can occur with Illuccix PET. A negative image does not rule out the presence of prostate cancer, and a positive image does not confirm the presence of prostate cancer. Gallium Ga 68 gozetotide uptake is not specific for prostate cancer and may occur with other types of cancer as well as non-malignant processes such as Paget’s disease, fibrous dysplasia, and osteophytosis. Clinical correlation, which may include histopathological evaluation of the suspected prostate cancer site, is recommended.

Imaging Prior to Initial Definitive or Suspected Recurrence Therapy
The performance of Illuccix for imaging of biochemically recurrent prostate cancer seems to be affected by serum PSA levels and by site of disease. The performance of Illuccix for imaging of metastatic pelvic lymph nodes prior to initial definitive therapy seems to be affected by Gleason score.

Radiation Risks
Gallium Ga 68 gozetotide contributes to a patient’s overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk for cancer. Ensure safe handling to minimize radiation exposure to the patient and healthcare providers. Advise patients to hydrate before and after administration and to void frequently after administration.

ADVERSE REACTIONS
The safety of gallium Ga 68 gozetotide was evaluated in 960 patients in the PSMA-PreRP and PSMA-BCR studies, each receiving one dose of gallium Ga 68 gozetotide. The average injected activity was 188.7 ± 40.7 MBq (5.1 ± 1.1 mCi). The most commonly reported adverse reactions were nausea, diarrhea, and dizziness, occurring at a rate of <1%.

In the VISION study, 1003 patients received one dose of gallium Ga 68 gozetotide intravenously with the amount of radioactivity 167.1 ± 23.1 MBq (4.52 ± 0.62 mCi). Adverse reactions occurring at ≥0.5% in patients with metastatic prostate cancer who received gallium Ga 68 gozetotide injection in the clinical study were fatigue (1.2%), nausea (0.8%), constipation (0.5%), and vomiting (0.5%).
Adverse reactions occurring at a rate of < 0.5% in the VISION study were diarrhea, dry mouth, injection site reactions, including injection site hematoma and injection site warmth and chills.

DRUG INTERACTIONS
Androgen deprivation therapy and other therapies targeting the androgen pathway
Androgen deprivation therapy (ADT) and other therapies targeting the androgen pathway, such as androgen receptor antagonists, can result in changes in uptake of gallium Ga 68 gozetotide in prostate cancer. The effect of these therapies on performance of gallium Ga 68 gozetotide PET has not been established.

Please note that this information is not comprehensive.
Please see the Full Prescribing Information here.

About Gozellix® (kit for the preparation of gallium Ga 68 gozetotide injection)

Gozellix, after radiolabeling with ⁶⁸Ga, is indicated for PET scanning of PSMA positive lesions in men with prostate cancer who have suspected metastasis and are candidates for initial definitive therapy, and those with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level.

IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS

Risk for Misinterpretation
Image interpretation errors can occur with GOZELLIX PET. A negative image does not rule out the presence of prostate cancer, and a positive image does not confirm the presence of prostate cancer. Gallium Ga-68 gozetotide uptake is not specific for prostate cancer and may occur with other types of cancer as well as non-malignant processes such as Paget’s disease, fibrous dysplasia, and osteophytosis. Clinical correlation, which may include histopathological evaluation of the suspected prostate cancer site, is recommended.

Imaging Prior to Initial Definitive or Suspected Recurrence Therapy
The performance of GOZELLIX for imaging of biochemically recurrent prostate cancer seems to be affected by serum PSA levels and by site of disease. The performance of GOZELLIX for imaging of metastatic pelvic lymph nodes prior to initial definitive therapy seems to be affected by Gleason score.

Radiation Risks
Gallium Ga-68 gozetotide contributes to a patient’s overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk for cancer. Ensure safe handling to minimize radiation exposure to the patient and healthcare providers. Advise patients to hydrate before and after administration and to void frequently after administration.

Hypersensitivity Reactions to Sulfites
Ascorbic Acid Stabilizer contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in non-asthmatic people.

ADVERSE REACTIONS
The safety of gallium Ga-68 gozetotide was evaluated in 960 patients in the PSMA-PreRP and PSMABCR studies, each receiving one dose of gallium Ga-68 gozetotide. The average injected activity was 188.7 ± 40.7 MBq (5.1 ± 1.1 mCi). The most commonly reported adverse reactions were nausea, diarrhea, and dizziness, occurring at a rate of <1%.

DRUG INTERACTIONS
Androgen deprivation therapy and other therapies targeting the androgen pathway Androgen deprivation therapy (ADT) and other therapies targeting the androgen pathway, such as androgen receptor antagonists, can result in changes in uptake of gallium Ga-68 gozetotide in prostate cancer. The effect of these therapies on performance of gallium Ga-68 gozetotide PET has not been established.

Please note that this information is not comprehensive.
Please see the Full Prescribing Information here.

About Telix Pharmaceuticals Limited

Telix is a biopharmaceutical company focused on the development and commercialization of therapeutic and diagnostic radiopharmaceuticals and associated medical technologies. Telix is headquartered in Melbourne, Australia, with international operations in the United States, United Kingdom, Brazil, Canada, Europe (Belgium and Switzerland), and Japan. Telix is developing a portfolio of clinical and commercial stage products that aims to address significant unmet medical needs in oncology and rare diseases. Telix is listed on the Australian Securities Exchange (ASX: TLX) and the Nasdaq Global Select Market (NASDAQ: TLX).

Illuccix, Telix’s first generation PSMA-PET imaging agent, has been approved in multiple markets globally. Gozellix has been approved by the U.S. FDA¹⁰. Illuccix and Gozellix have not received regulatory approval for initial diagnosis of prostate cancer in any jurisdiction.

Visit www.telixpharma.com for further information about Telix, including details of the latest share price, ASX and U.S. Securities and Exchange Commission (SEC) filings, investor and analyst presentations, news releases, event details and other publications that may be of interest. You can also follow Telix on LinkedIn, X and Facebook.

Telix Investor Relations

Ms. Kyahn Williamson
Telix Pharmaceuticals Limited
SVP Investor Relations and Corporate Communications
Email: kyahn.williamson@telixpharma.com

Telix Investor Relations (U.S.)  

Annie Kasparian  
Telix Pharmaceuticals Limited  
Director Investor Relations and Corporate Communications  
Email: annie.kasparian@telixpharma.com 

Media Contact

Eliza Schleifstein
917.763.8106 (Mobile)
Eliza@schleifsteinpr.com

Legal Notices

Cautionary Statement Regarding Forward-Looking Statements. 

You should read this announcement together with our risk factors, as disclosed in our most recently filed reports with the Australian Securities Exchange (ASX), U.S. Securities and Exchange Commission (SEC), including our Annual Report on Form 20-F filed with the SEC, or on our website.

The information contained in this announcement is not intended to be an offer for subscription, invitation or recommendation with respect to securities of Telix Pharmaceuticals Limited (Telix) in any jurisdiction, including the United States. The information and opinions contained in this announcement are subject to change without notification.  To the maximum extent permitted by law, Telix disclaims any obligation or undertaking to update or revise any information or opinions contained in this announcement, including any forward-looking statements (as referred to below), whether as a result of new information, future developments, a change in expectations or assumptions, or otherwise. No representation or warranty, express or implied, is made in relation to the accuracy or completeness of the information contained or opinions expressed in the course of this announcement.

This announcement may contain forward-looking statements, including within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, that relate to anticipated future events, financial performance, plans, strategies or business developments. Forward-looking statements can generally be identified by the use of words such as “may”, “expect”, “intend”, “plan”, “estimate”, “anticipate”, “believe”, “outlook”, “forecast” and “guidance”, or the negative of these words or other similar terms or expressions. Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to differ materially from any future results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. Forward-looking statements are based on Telix’s good-faith assumptions as to the financial, market, regulatory and other risks and considerations that exist and affect Telix’s business and operations in the future and there can be no assurance that any of the assumptions will prove to be correct. In the context of Telix’s business, forward-looking statements may include, but are not limited to, statements about: the initiation, timing, progress, completion and results of Telix’s preclinical and clinical trials, and Telix’s research and development programs; Telix’s ability to advance product candidates into, enroll and successfully complete, clinical studies, including multi-national clinical trials; the timing or likelihood of regulatory filings and approvals for Telix’s product candidates, including the planned NDA resubmission for TLX101-Px and the planned BLA resubmission for TLX250-Px, manufacturing activities and product marketing activities; Telix’s sales, marketing and distribution and manufacturing capabilities and strategies; the commercialization of Telix’s product candidates, if or when they have been approved; Telix’s ability to obtain an adequate supply of raw materials at reasonable costs for its products and product candidates; estimates of Telix’s expenses, future revenues and capital requirements; Telix’s financial performance; developments relating to Telix’s competitors and industry; the anticipated impact of U.S. and foreign tariffs and other macroeconomic conditions on Telix’s business; and the pricing and reimbursement of Telix’s product candidates, if and after they have been approved. Telix’s actual results, performance or achievements may be materially different from those which may be expressed or implied by such statements, and the differences may be adverse. Accordingly, you should not place undue reliance on these forward-looking statements.

Trademarks and Trade Names. All trademarks and trade names referenced in this press release are the property of Telix Pharmaceuticals Limited (Telix) or, where applicable, the property of their respective owners. For convenience, trademarks and trade names may appear without the ® or ™ symbols. Such omissions are not intended to indicate any waiver of rights by Telix or the respective owners. Trademark registration status may vary from country to country. Telix does not intend the use or display of any third-party trademarks or trade names to imply any affiliation with, endorsement by, or sponsorship from those third parties.

©2026 Telix Pharmaceuticals Limited. All rights reserved.

________________________

¹ Imaging of prostate-specific membrane antigen with positron emission tomography.
² Positron emission tomography.
³ Magnetic resonance imaging.
⁴ Prostate-specific antigen.
⁵ Durkan G et al. Prostate Cancer Prostatic Dis. 2000.
⁶ Vickers et al. J Clin Oncol. 2010.
⁷ Schaufler C et al. Urologic Oncology: Seminars and Original Investigations. 2022.
⁸ Emmett et al., Eur Urol. 2021.
⁹ ClinicalTrials.gov ID: NCT05154162. Sponsor: Peter MacCallum Cancer Centre, Australia.
¹⁰ Telix ASX disclosure 21 March 2025.

FAQ

What did Telix (TLX) announce on January 16, 2026 about the BiPASS trial?

Telix announced the first U.S. patient was dosed in BiPASS, a Phase 3 study of Illuccix and Gozellix 68Ga-PSMA-11 PET for pre-biopsy prostate cancer diagnosis.

How many patients will the BiPASS Phase 3 trial (TLX) enroll and where?

BiPASS is a prospective, open-label Phase 3 trial that will enroll 250 patients across sites in the U.S. and Australia.

What is the primary goal of the BiPASS trial for Telix (TLX)?

The trial aims to determine whether combining MRI with Illuccix/Gozellix 68Ga-PSMA-11 PET improves diagnostic accuracy and reduces unnecessary biopsies, potentially supporting marketing authorization in the pre-biopsy setting.

What potential clinical impact did Telix (TLX) highlight for successful BiPASS results?

If primary objectives are met, BiPASS could enable biopsy de-escalation, greater biopsy precision, improved patient experience, and expanded access to precision imaging.

Why is reducing biopsies clinically relevant according to the BiPASS announcement by TLX?

The release notes that in the U.S. more than 1 million prostate biopsies occur annually and up to 75% are negative, indicating scope to reduce unnecessary procedures if imaging improves stratification.