Exhibit 99.1

Adaptive Biotechnologies Corporation Announces Proposed Convertible Senior Notes Offering

SEATTLE—(GLOBE NEWSWIRE)—June 15, 2026—Adaptive Biotechnologies Corporation (“Adaptive Biotechnologies”) (Nasdaq: ADPT) today announced its intention to offer, subject to market and other conditions, $250 million aggregate principal amount of convertible senior notes due 2031 (the “notes”) in a private offering to persons reasonably believed to be qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). Adaptive Biotechnologies also expects to grant the initial purchasers of the notes an option to purchase, for settlement within a period of 13 days from, and including, the date the notes are first issued, up to an additional $37.5 million aggregate principal amount of notes.

The notes will be senior, unsecured obligations of Adaptive Biotechnologies, will accrue interest payable semi-annually in arrears and will mature on July 1, 2031, unless earlier repurchased, redeemed or converted. Noteholders will have the right to convert their notes in certain circumstances and during specified periods. Adaptive Biotechnologies will settle conversions by paying or delivering, as applicable, cash, shares of its common stock or a combination of cash and shares of its common stock, at Adaptive Biotechnologies’s election.

The notes will be redeemable, in whole or in part (subject to certain limitations), for cash at Adaptive Biotechnologies’s option at any time, and from time to time, on or after July 1, 2029 and on or before the 40th scheduled trading day immediately before the maturity date, but only if the last reported sale price per share of Adaptive Biotechnologies’s common stock exceeds 130% of the conversion price for a specified period of time and certain other conditions are satisfied. In addition, the notes will be redeemable, in whole and not in part, at Adaptive Biotechnologies’s option at any time, if the aggregate principal amount of the notes that remain outstanding is less than 15% of the aggregate principal amount of notes initially issued under the indenture and certain other conditions are satisfied. The redemption price will be equal to the principal amount of the notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date.

If certain corporate events that constitute a “fundamental change” occur, then, subject to a limited exception, noteholders may require Adaptive Biotechnologies to repurchase their notes for cash. The repurchase price will be equal to the principal amount of the notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the applicable repurchase date.

The interest rate, initial conversion rate and other terms of the notes will be determined at the pricing of the offering.

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Adaptive Biotechnologies intends to use a portion of the net proceeds from the offering to fund the cost of entering into the capped call transactions described below. Adaptive Biotechnologies expects to use up to $25 million of the net proceeds from the offering to repurchase shares of its common stock concurrently with the pricing of the offering in privately negotiated transactions effected through one of the initial purchasers of the notes or its affiliate, as Adaptive Biotechnologies’s agent. Adaptive Biotechnologies intends to use the remainder of the net proceeds from the offering for the repayment of the OrbiMed Purchase Agreement, general corporate purposes and opportunistic initiatives in the MRD business. If the initial purchasers exercise their option to purchase additional notes, then Adaptive Biotechnologies intends to use a portion of the additional net proceeds to fund the cost of entering into additional capped call transactions as described below. The concurrent repurchases of shares of Adaptive Biotechnologies’s common stock described above may result in Adaptive Biotechnologies’s common stock trading at prices that are higher than would be the case in the absence of these repurchases, which may result in a higher initial conversion price for the notes Adaptive Biotechnologies is offering.

In connection with the pricing of the notes, Adaptive Biotechnologies has been advised that J. Wood Capital Advisors LLC (“JWCA”), Adaptive Biotechnologies’s financial advisor with respect to the offering, intends to purchase up to $10 million of shares of common stock concurrently with the offering in privately negotiated transactions with institutional investors through one of the initial purchasers or its affiliate (the “JWCA Purchase”).

In connection with the pricing of the notes, Adaptive Biotechnologies expects to enter into privately negotiated capped call transactions with one or more of the initial purchasers or their affiliates or one or more other financial institutions (the “option counterparties”). The capped call transactions are expected to cover, subject to anti-dilution adjustments substantially similar to those applicable to the notes, the number of shares of Adaptive Biotechnologies’s common stock that will initially underlie the notes. If the initial purchasers exercise their option to purchase additional notes, then Adaptive Biotechnologies expects to enter into additional capped call transactions with the option counterparties.

The capped call transactions are expected generally to reduce the potential dilution to Adaptive Biotechnologies’s common stock upon any conversion of the notes and/or offset any potential cash payments Adaptive Biotechnologies is required to make in excess of the principal amount of converted notes, as the case may be, upon conversion of the notes. If, however, the market price per share of Adaptive Biotechnologies’s common stock, as measured under the terms of the capped call transactions, exceeds the cap price of the capped call transactions, there would nevertheless be dilution and/or there would not be an offset of such potential cash payments, in each case, to the extent that such market price exceeds the cap price of the capped call transactions.

In connection with establishing their initial hedges of the capped call transactions, the option counterparties or their respective affiliates expect to enter into various derivative transactions with respect to Adaptive Biotechnologies’s common stock and/or purchase shares of Adaptive Biotechnologies’s common stock concurrently with or shortly after the pricing of the notes. This activity, as well as the JWCA Purchase, could increase (or reduce the size of any decrease in) the market price of Adaptive Biotechnologies’s common stock or the notes at that time.

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In addition, the option counterparties or their respective affiliates may modify their hedge positions by entering into or unwinding various derivatives with respect to Adaptive Biotechnologies’s common stock and/or purchasing or selling Adaptive Biotechnologies’s common stock or other securities of Adaptive Biotechnologies in secondary market transactions following the pricing of the notes and prior to the maturity of the notes (and (x) are likely to do so during any observation period related to a conversion of notes or following any repurchase of notes by Adaptive Biotechnologies in connection with any fundamental change and (y) may do so following any repurchase of notes by Adaptive Biotechnologies other than in connection with any fundamental change). This activity, as well as the JWCA Purchase, could also cause or avoid an increase or decrease in the market price of Adaptive Biotechnologies’s common stock or the notes, which could affect the ability to convert the notes, and, to the extent the activity occurs during any observation period related to a conversion of notes, it could affect the number of shares and value of the consideration that noteholders will receive upon conversion of the notes.

The offer and sale of the notes and any shares of common stock issuable upon conversion of the notes have not been, and will not be, registered under the Securities Act or any other securities laws, and the notes and any such shares cannot be offered or sold except pursuant to an exemption from, or in a transaction not subject to, the registration requirements of the Securities Act and any other applicable securities laws. This press release does not constitute an offer to sell, or the solicitation of an offer to buy, the notes or any shares of common stock issuable upon conversion of the notes, nor will there be any sale of the notes or any such shares, in any state or other jurisdiction in which such offer, sale or solicitation would be unlawful.

About Adaptive Biotechnologies

Adaptive Biotechnologies (“we” or “our”) is a commercial-stage biotechnology company focused on harnessing the inherent biology of the adaptive immune system to transform the diagnosis and treatment of disease. We believe the adaptive immune system is nature’s most finely tuned diagnostic and therapeutic for most diseases, but the inability to decode it has prevented the medical community from fully leveraging its capabilities. Our proprietary immune medicine platform reveals and translates the massive genetics of the adaptive immune system with scale, precision and speed. We apply our platform to partner with biopharmaceutical companies, inform drug development, and develop clinical diagnostics across our two business segments: Minimal Residual Disease (MRD) and Immune Medicine. Our commercial products and clinical pipeline enable the diagnosis, monitoring, and treatment of diseases such as cancer and autoimmune disorders. Our goal is to develop and commercialize immune-driven clinical products tailored to each individual patient.

Forward-Looking Statements

This press release includes forward-looking statements, including statements regarding the anticipated terms of the notes being offered, the completion, timing and size of the proposed offering, the intended use of the proceeds and the anticipated terms of, and the effects of entering into, the capped call transactions described above. Forward-looking statements represent Adaptive Biotechnologies’s current expectations regarding future events and are subject to known and unknown risks and uncertainties that could cause actual results to differ materially from those implied by the forward-looking statements.

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Among those risks and uncertainties are market conditions, including market interest rates, the trading price and volatility of Adaptive Biotechnologies’s common stock and risks relating to Adaptive Biotechnologies’s business, including those described in periodic reports that Adaptive Biotechnologies files from time to time with the SEC. Adaptive Biotechnologies may not consummate the proposed offering described in this press release and, if the proposed offering is consummated, cannot provide any assurances regarding the final terms of the offering or the notes or its ability to effectively apply the net proceeds as described above. The forward-looking statements included in this press release speak only as of the date of this press release, and Adaptive Biotechnologies does not undertake to update the statements included in this press release for subsequent developments, except as required by law.

Contact Information

Karina Calzadilla, Vice President, Investor Relations and FP&A

201-396-1687

investors@adaptivebiotech.com

Erica Jones, Associate Corporate Communications Director

206-279-2423

media@adaptivebiotech.com

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Exhibit 99.2

Adaptive Biotechnologies Announces Plan to Separate Its MRD and Immune Medicine Businesses

MRD has scaled into a profitable, category-leading MRD diagnostics business, while

Immune Medicine has built a differentiated discovery platform powered by proprietary immune data and AI

SEATTLE, June 15, 2026 (GLOBE NEWSWIRE) – Adaptive Biotechnologies Corporation (Nasdaq: ADPT), a commercial-stage biotechnology company focused on translating the genetics of the adaptive immune system into clinical products to diagnose and treat disease, today announced its intention to pursue a separation of its Minimal Residual Disease (MRD) and Immune Medicine businesses. The company is evaluating strategic and structural alternatives for Immune Medicine to support its growth strategy, capital needs, and value creation opportunities outside of Adaptive, and expects to identify its preferred path to separation by year-end 2026.

Since establishing MRD and Immune Medicine as separate operating segments under Adaptive in 2024, both businesses have continued to advance. MRD has achieved significant scale, expanded reimbursement, strengthened its clinical evidence base and reached profitability, establishing clonoSEQ® as a leading platform in MRD testing.

At the same time, Immune Medicine has continued to build a uniquely differentiated discovery platform anchored by the world’s largest clinically linked immune receptor dataset and enhanced by advances in AI-driven discovery. The platform is increasingly demonstrating its potential to generate novel biological insights, identify therapeutic targets, and accelerate the development of precision medicines. As Immune Medicine enters its next phase of growth, the company believes the value of its differentiated assets may be best realized outside of a diagnostic commercial model.

“When we completed our strategic review in 2024, we decided to continue developing both MRD and Immune Medicine within Adaptive while increasing their operational independence,” said Chad Robins, Chief Executive Officer and Co-Founder of Adaptive Biotechnologies. “The progress achieved by both businesses has reinforced that decision. As we look ahead, Adaptive will focus on expanding its leadership in MRD diagnostics, while pursuing the optimal path for Immune Medicine outside of Adaptive. We believe this separation is the best way to unlock the full potential of both businesses, increasing their impact on patients and creating long-term value for shareholders.”

About the MRD business

Adaptive’s MRD business has achieved significant scale, profitability and expanded clinical utility. Revenue has grown from $103 million in 2023 to $212 million in 2025 and the business has reported $15 million in 2025 adjusted EBITDA (non-GAAP). With more than 300 million covered lives, over 175 EMR integrated accounts and greater than 180 active biopharma trials, clonoSEQ is increasingly embedded in routine clinical practice and drug development.

About the Immune Medicine business

Immune Medicine has progressed its data and drug discovery capabilities to uncover causal immune drivers to enable precision medicine in autoimmune diseases. With over 6 million functional T-cell receptor (TCR)-antigen pairs and well-characterized data sets on more than 10,000 patients, Immune Medicine is discovering pathogenic TCRs and the disease-causing antigens they bind.

There can be no assurance that this process will result in any transaction or other outcome, or as to the timing or terms of any such transaction. Adaptive does not intend to disclose further developments unless and until it determines that further disclosure is appropriate or required.

Forward-Looking Statements

This press release contains forward-looking statements that are based on management’s beliefs and assumptions and on information currently available to management. All statements contained in this release other than statements of historical fact are forward-looking statements, including statements regarding Adaptive’s business strategies, strategic focus, review of strategic alternatives for Immune Medicine, potential sale, separation, partnership, licensing transaction or other strategic or operational outcome involving Immune Medicine, the timing and outcome of any strategic review process, the growth, profitability, reimbursement, clinical adoption and commercial opportunity of the MRD business, the market opportunity for clonoSEQ, expected margin expansion, disciplined capital allocation, company-wide profitability and plans and objectives for future operations.

In some cases, forward-looking statements can be identified by words such as “may,” “will,” “could,” “would,” “should,” “expect,” “intend,” “plan,” “anticipate,” “believe,” “estimate,” “predict,” “project,” “potential,” “continue,” “ongoing,” “focus,” “opportunity,” “evaluate,” or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words.

These statements involve risks, uncertainties and other factors that may cause actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these forward-looking statements. These risks, uncertainties and other factors are described under “Risk Factors,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and elsewhere in the documents Adaptive files with the Securities and Exchange Commission from time to time. Adaptive cautions that forward-looking statements are based on a combination of facts and factors currently known to the company and projections of the future, about which Adaptive cannot be certain. As a result, the forward-looking statements may not prove to be accurate. The forward-looking statements in this press release represent Adaptive’s views as of the date hereof. Adaptive undertakes no obligation to update any forward-looking statements for any reason, except as required by law.

ADAPTIVE INVESTORS

Karina Calzadilla, Vice President, Investor Relations and FP&A

201-396-1687

investors@adaptivebiotech.com

ADAPTIVE MEDIA

Erica Jones, Associate Corporate Communications Director

206-279-2423

media@adaptivebiotech.com

Exhibit 99.3

In connection with its previous announcements regarding the planned separation of its Immune Medicine businesses and the launch of a convertible notes offering, Adaptive Biotechnologies Inc. (“we,” “us” and “our”) is providing this statement.

Recent Developments

Separation of Immune Medicine Business

Since establishing MRD and Immune Medicine as separate operating segments in 2024, both businesses have continued to advance. MRD has achieved significant scale, expanded reimbursement, strengthened its clinical evidence base and reached profitability, establishing clonoSEQ® as a leading platform in MRD clinical and biopharma testing.

At the same time, Immune Medicine has continued to build a uniquely differentiated discovery platform anchored by the world’s largest clinically linked immune receptor dataset and enhanced by advances in AI-driven discovery. The platform is increasingly demonstrating its potential to generate novel biological insights, identify therapeutic targets, and accelerate the development of precision medicines. Immune Medicine has progressed its data and drug discovery capabilities to uncover causal immune drivers to enable precision medicine in autoimmune diseases. With over 6 million functional TCR-antigen pairs and well-characterized data sets on more than 10,000 patients, Immune Medicine is discovering pathogenic TCRs and the disease-causing antigens they bind.

As Immune Medicine enters its next phase of growth, we believe the long-term potential of its differentiated assets may be best realized outside of a diagnostic commercial model. As a result, we have reached an inflection point where we believe separating the businesses would enable each to pursue its distinct strategic priorities, capital requirements, and growth opportunities.

Following a separation, Adaptive would continue as the MRD business, building on its leadership position in MRD diagnostics and biopharma testing. We are evaluating strategic and structural alternatives for Immune Medicine to pursue its growth strategy, capital needs, and value creation opportunities outside of Adaptive, and expect to identify our preferred path to separation by year end. We believe this path offers the greatest opportunity to unlock the full potential of both businesses and create long-term value for shareholders.

Leadership for Immune Medicine, where Dr. Harlan Robins, our Chief Scientific Officer, has been primarily focused, will be determined as its strategic alternatives become clearer. Additionally, in line with his continued obligations to Adaptive and as approved by our board of directors, Dr. Robins formed a new data-sharing, cloud-computing company, where he is the founder and a director but not a paid employee. As the strategy for Immune Medicine is finalized, the allocation of Dr. Robins’ time may change. Executive leadership for Adaptive and the MRD business remains intact, and Dr. Robins continues to support research and development efforts for the MRD business.

Repayment of OrbiMed Purchase Agreement

In September 2022, we entered into a revenue interest purchase agreement (the “OrbiMed Purchase Agreement”) with OrbiMed Royalty & Credit Opportunities IV, LP (“OrbiMed”), an affiliate of OrbiMed Advisors LLC, as collateral agent and administrative agent for the purchasers party thereto (the “Purchasers”). Pursuant to the OrbiMed Purchase Agreement, we received $124.4 million from the Purchasers (the “Purchaser Payment”), net of expenses. As consideration for such payments, the Purchasers have a right to receive certain revenue interest payments from us each quarter based on a current rate of five percent of all GAAP revenue, subject to adjustment in September 2028 as provided in the OrbiMed Purchase Agreement. OrbiMed will be entitled to 100% of the revenue interest payments until it has received a total cumulative value of 165% of the Purchaser Payment (the “Return Cap”), unless full repayment of the amount of the Return Cap has not been made by September 12, 2032, in which case the Return Cap shall be increased to 175% of the Purchaser Payment. To secure our obligations under the OrbiMed Purchase Agreement, we and our subsidiaries have granted OrbiMed a security interest in our core platform technology assets, subject to certain customary exclusions, as defined in the OrbiMed Purchase Agreement.

OrbiMed has waived various covenants in the OrbiMed Purchase Agreement that otherwise would have restricted our ability to conduct this offering and agreed to allow us to repay the Purchaser Payment at a Return Cap of 156%, which results in a payoff amount of $156.9 million. We intend to repay this amount using the proceeds from this offering, and then to terminate the OrbiMed Purchase Agreement.

Risks Relating to our Business

We may not realize the anticipated benefits of separating our Immune Medicine business from our MRD business.

As our Immune Medicine business enters its next phase of growth, we believe the long-term potential of its differentiated assets may be best realized outside of a diagnostic commercial model of our MRD business. However, we may not achieve the anticipated operational, financial, strategic and other benefits of the separation. If strategic and structural alternatives for Immune Medicine do not emerge, we may not succeed in separating it from our MRD business, and any alternatives that do become available to us may have commercially challenging terms. Even if we do separate our Immune Medicine business, it may be unable to access the required capital, personnel, technology, or other resources necessary for the businesses to separately pursue its growth opportunities. Whether or not the separation is successful, pursuing the separation may distract our management, require time and resources, or adversely impact our operations, employee retention and morale, customer and partner retention, and other important relationships. As a result, we may not realize the anticipated benefits of separating our Immune Medicine business from our MRD business.

Forward-Looking Statements

This statement includes forward-looking statements, including statements regarding the separation of the Immune Medicine business, repayment of the OrbiMed Purchase Agreement, completion of the offering, and the expected amount and intended use of the net proceeds described above. Forward-looking statements represent Adaptive Biotechnologies’ current expectations regarding future events and are subject to known and unknown risks and uncertainties that could cause actual results to differ materially from those implied by the forward-looking statements. Among those risks and uncertainties are market conditions, the satisfaction of the closing conditions related to the offering and risks relating to Adaptive Biotechnologies’ business, including those described in periodic reports that Adaptive Biotechnologies files from time to time with the Securities and Exchange Commission.

Adaptive Biotechnologies may not consummate the separation of the Immune Medicine business, repayment of the OrbiMed Purchase Agreement, and the offering described in this statement. The forward-looking statements included in this press release speak only as of the date of this press release, and Adaptive Biotechnologies does not undertake to update the statements included in this press release for subsequent developments, except as required by law.