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Business Update
Aptevo Therapeutics, Inc. (NASDAQ: APVO) is currently focused on the continued clinical progress with mipletamig, a $1.5 million non-dilutive grant to advance APVO451, and the company’s recently established 50/50 collaboration with Niowave to develop radiopharmaceutical oncology programs. While Aptevo has historically emphasized the breadth of its multispecific antibody pipeline, management is increasingly focused on those three areas to assist investors in evaluating the company while continuing to maintain the longer-term optionality provided by the ADAPTIR and ADAPTIR-FLEX platforms.
Mipletamig Development Continues
Mipletamig remains Aptevo’s most advanced and important value driver, with the Phase 1b/2 RAINIER study continuing to generate encouraging data in frontline acute myeloid leukemia (AML) patients who are unfit for intensive chemotherapy. Updated results from 31 evaluable patients treated with mipletamig in combination with venetoclax and azacitidine demonstrated an 87% clinical benefit rate and an 81% remission rate. The updated dataset also provides additional evidence regarding the depth of responses, with 55% of patients who achieved CR/CRi reaching measurable residual disease negative level, a result that is typically associated with strong, more durable responses. In addition, 36% of patients achieving remission had TP53 mutations, a high-risk AML subgroup associated with particularly poor outcomes, while six patients treated to date have proceeded to allogenic stem cell transplantation.
Mipletamig continues to exhibit a favorable safety profile. No cytokine release syndrome (CRS) has been reported among frontline patients through Cohort 5 of RAINIER, supporting the possibility that mipletamig’s proprietary CRIS-7 derived CD3-binding domain may provide a differentiated tolerability profile. The absence of CRS is particularly relevant given the challenges associated with CD3-engaging therapies and the importance of combining mipletamig with venetoclax and azacitidine in the frontline AML setting.
RAINIER has now entered the final stage of dose optimization. Aptevo expects to complete the Phase 1b portion of the study and select a recommended Phase 2 dose by year-end 2026, followed by a regulatory interaction regarding Phase 2 development in 1Q27. We view these milestones as the most important near-term catalysts for the company, as they should provide greater clarity on the optimal dosing strategy and the design and regulatory path for a potentially pivotal development program.
Mipletamig is Aptevo’s lead clinical-stage immunotherapy candidate and currently represents the company’s primary value driver. The molecule is a CD123 x CD3 bispecific T cell engager generated using the company’s proprietary ADAPTIR platform and was specifically engineered to redirect endogenous cytotoxic T cells toward leukemic blasts and leukemic stem cells expressing CD123. Unlike many earlier-generation T cell engagers that utilized highly potent CD3-binding domains associated with substantial CRS, mipletamig incorporates Aptevo’s proprietary CRIS-7-derived CD3 binding domain, which was designed to preserve anti-leukemic activity while reducing excessive immune activation and inflammatory cytokine release. In our view, this engineered balance between efficacy and tolerability represents one of the most important differentiating features of the program.
Non-Dilutive Funding Secured for APVO451
In June 2026, Aptevo announced it was awarded a $1.5 million non-dilutive research grant from the Andy Hill Cancer Research Endowment (CARE) Fund to support investigational new drug (IND)-enabling work for APVO451, a Nectin-4-targeted trispecific immunotherapy candidate being developed for solid tumors. The competitively awarded funding provides external validation of the program while allowing Aptevo to advance the candidate without relying entirely on shareholder capital.
Aptevo is targeting development candidate selection for APVO451 by the end of 2026, with IND-enabling studied expected to begin in 1Q27. This is an important development because it gives Aptevo a second internally generated program with a defined path toward clinical development.
Importantly, Aptevo is also building a broader intellectual-property strategy around Nectin-4. In July 2026, the company announced the filing of a provisional patent application covering a Nectin-4 x PD-L1 dual-targeting backbone that it believes could serve as the foundation for multiple solid tumor therapeutic approaches. The proposed backbone is designed to combine Nectin-4 tumor targeting with PD-L1 targeting and could potentially be incorporated into T cell engagers, radiopharmaceuticals, and other immune-based therapies.
This filing is strategically important because it potentially expands the opportunity beyond APVO451 itself. Nectin-4 provides a tumor-associated target already being pursued by Aptevo through APVO451, while adding PD-L1 could provide an additional tumor-localization mechanism and the opportunity to modulate the immunosuppressive tumor microenvironment. In addition, the same targeting architecture could potentially be leveraged across different therapeutic modalities, including the radiopharmaceutical programs being pursued with Niowave. In this context, the patent filing supports management’s effort to build a reusable solid tumor platform rather than a single Nectin-4 product, potentially creating additional opportunities for internal development and partnering.
Niowave Partnership
Another area of Aptevo’s strategic focus is its collaboration with Niowave, which was announced in May 2026. The companies are collaborating on the development of up to three radiopharmaceutical oncology programs, with development costs shared equally. Aptevo contributes its tumor-targeting and multispecific antibody expertise, while Niowave contributes expertise in radioisotope production and supply, including access to Actinium-225.
We view the collaboration as adding attractive long-term value because it allows Aptevo to enter the rapidly developing radiopharmaceutical field without having to build the underlying isotope infrastructure internally. The partnership also provides access to radioisotope supply, which can be an important constraint for companies attempting to develop radiopharmaceutical therapies. Niowave further invested in Aptevo at the closing of the collaboration, initially acquiring a 7.9% ownership stake and retaining the potential to increase its ownership to 19.99% through warrant exercises and future purchases.
While mostly adding long-term upside to the story, the opportunity will become more tangible as the companies identify specific development programs in addition to the previously announced targeting assets directed against Nectin-4. Until then, the principal investment benefit is the potential to expand Aptevo’s tumor targeting-technology into an attractive therapeutic modality while sharing development costs with a strategic partner.
Financial Update
On August 13, 2026, Aptevo announced financial results for the second quarter of 2026. As expected, the company did not report any revenue in the second quarter of 2026. R&D expenses in the second quarter of 2026 were $3.7 million compared to $3.3 million for the second quarter of 2025. The increase was primarily due to higher mipletamig clinical study costs, preclinical testing costs, and consulting fees. G&A expenses in the second quarter of 2026 were $2.7 million compared to $2.9 million in the second quarter of 2025. The decrease was primarily due to lower employee costs.
Aptevo exited the second quarter of 2026 with approximately $9.8 million in cash and cash equivalents. Subsequent to the end of the quarter, the company entered into warrant inducement letter agreements with certain holders of existing warrants, in which those holders agreed to exercise in full for cash their existing warrants to purchase up to an aggregate 254,922 shares of common stock for $4.03 per share. Concurrently, Aptevo entered into a private placement with certain purchasers for the sale of up to 861,708 unregistered shares of common stock at a price of $4.03. The aggregate gross proceeds from the transactions were approximately $4.5 million. As of August 14, 2026, Aptevo had approximately 1.8 million shares outstanding and, when factoring in stock options and warrants, a fully diluted share count of approximately 7.9 million.
Conclusion
We believe Aptevo is focusing its investment story on the core, value-driving programs. Mipletamig remains the central value driver, with the RAINIER study moving toward completion of dose optimization and a Phase 2 regulatory interaction in 1Q27. The 87% clinical benefit rate, 81% remission rate, MRD-negative responses, activity in TP53-mutated patients, and ability to bridge six patients to transplant provide encouraging evidence of clinical activity, while the absence of CRS in frontline patients remains a potentially important differentiating characteristic.
At the same time, APVO451 provides a second internally controlled opportunity that is now advancing toward candidate selection and IND-enabling studies with the benefit of non-dilutive funding. The Niowave collaboration adds a third source of long-term optionality, giving Aptevo a capital-efficient entry into radiopharmaceutical therapeutics. The most important upcoming milestones are completion of mipletamig dose optimization and Phase 2 planning, APVO451 candidate selection, and further definition of the radiopharmaceutical programs to be pursued with Niowave. The recent financing was already incorporated into our model, thus our valuation remains at $30 per share.
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