On April 19, 2026 CStone Pharmaceuticals ("CStone," HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, immunology, inflammation, and other key disease areas, reported that the Company presented the latest preclinical data for three proprietary pipeline assets at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting (from April 17 to 22), including CS5007 (EGFR/HER3 ADC), CS5006 (ITGB4 ADC), and CS5008 (DLL3/SSTR2 ADC).

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CStone’s Proprietary ADC Technology Platform

All three antibody-drug conjugates (ADCs) presented at AACR (Free AACR Whitepaper) – CS5007 (EGFR/HER3 ADC), CS5006 (ITGB4 ADC), and CS5008 (DLL3/SSTR2 ADC) – are developed utilizing CStone’s proprietary ADC technology platform, which incorporates the following core features:

High Stability & Precise Payload Release: The platform utilizes CStone’s proprietary CSL20 linker, a hydrophilic construct designed for enhanced stability in circulation. Payload release is triggered selectively through a tandem cleavage mechanism involving the synergistic action of β-glucuronidase and cathepsin.
Potent Payload: Each ADC employs exatecan, a clinically validated and highly potent topoisomerase I inhibitor with a strong bystander effect and reduced sensitivity to multidrug resistance.
CS5007 – EGFR/HER3 Bispecific ADC

EGFR and HER3, members of the ErbB receptor family, are key oncogenic drivers frequently co-overexpressed across a variety of human epithelial malignancies. Although single-target EGFR therapies are widely utilized in standard-of-care treatments, adaptive resistance driven by compensatory HER3 signaling and heterodimerization substantially limits long-term clinical benefit. Therefore, dual targeting of EGFR and HER3 represents a highly promising strategy to overcome the tumor heterogeneity and resistance mechanisms that commonly compromise single-target approaches. CS5007 is designed to synergistically bind EGFR and HER3, which form extensive dimerization with other HER family members, thereby targeting almost all oncogenic HER-family receptor complexes (except HER2 homodimers) and effectively blocking the signaling cascades that promote tumor cell survival and proliferation.

CS5007 is a bispecific ADC comprising: 1) an anti-EGFR and HER3 human IgG1 antibody; 2) CStone’s proprietary hydrophilic CSL20 linker; 3) exatecan (Exa), a clinically validated topoisomerase I inhibitor, as the payload, conjugated with a drug-to-antibody ratio (DAR) of approximately 4.

Key Highlights:

1. Superior Molecular Stability

CS5007 demonstrates excellent stability in in vitro plasma stability tests, outperforming DS-8201 (trastuzumab deruxtecan) benchmark. After 7 days of incubation in plasma, free payload release was below 0.5%, indicating a low risk of off-target toxicity.

2. Dual Signaling Pathway Blockade

Western blot analysis was used to assess the signal-blocking capability of J17 (the naked antibody of CS5007) across various human tumor cell lines under a continuous stimulation microenvironment simulated by ligands (TGF-α/EGF and/or NRG1 β1). By dually targeting EGFR and HER3, CS5007 achieves potent inhibition of downstream signaling cascades, including the Akt and MAPK pathways. This dual blockade overcomes the inherent limitations and resistance mechanisms associated with single-target inhibition. Compared to SI-B001 (the naked antibody of BL-B01D1), CS5007’s antibody (J17) demonstrates superior inhibitory potency. Notably, while SI-B001 fails to interrupt HER3/Akt signaling in A431 and FaDu cells, J17 effectively abrogates these signals even under ligand-stimulated conditions.

3. Rapid and Deep Internalization

Using the Incucyte Real-Time Live-Cell Imaging, the internalization profile of CS5007 was evaluated in A431, BxPC-3, FaDu, SW620 and MDA-MB-468 cells with pH sensor dye. CS5007 was efficiently and rapidly internalized across all tested tumor cell lines in a concentration-dependent manner and efficiently trafficked to the lysosome. Similar results were observed for the naked antibody J17. Notably, in SW620 cells with low EGFR expression, CS5007 maintains efficient drug delivery through the HER3-mediated internalization pathway.

4. Potent and Broad-Spectrum In Vitro Anti-Tumor Activity

In vitro cytotoxicity was evaluated using CellTiter-Glo (CTG) luminescent assay across 6 human tumor cell lines. CS5007 exhibits potent, nanomolar-level, antigen-dependent cell-killing activity across a broad spectrum of tumor cell lines, including non-small cell lung cancer (NSCLC), squamous cell carcinoma (SCC), colorectal cancer (CRC), squamous cell carcinoma (SCCHN), pancreatic cancer (PANC), and breast cancer (BC).

5. Significant Bystander Killing Effect

The bystander effect of CS5007 was assessed using a co-culture system of NCI-H1568 cells (antigen-positive, Ag+) and NCI-H524 cells (antigen-negative, Ag-) by CTG and flow cytometry (FCM) assays. In mono-culture systems, CS5007 induced cytotoxicity on H1568 cells, but not on HCI-H524 cells. In the co-culture system, CS5007 eliminated not only antigen-positive (NCI-H1568) tumor cells but also adjacent antigen-negative (NCI-H524) tumor cells, demonstrating an ability to address tumor heterogeneity and expand the therapeutic range.

6. Broad-Spectrum In Vivo Anti-tumor Activity and Breakthrough in Resistant Models

CS5007 inhibited tumor growth in cell line-derived xenograft (CDX) models derived from multiple tumor types, including NSCLC, CRC, BC, SCCHN, and SCC.
CS5007 was effective in the osimertinib-resistant H1975 model (EGFR C797S mutation).
In the SW620 model with low EGFR expression and high HER3 expression, CS5007 achieved tumor clearance, whereas the comparator BL-B01D1 showed no meaningful activity.
7. Favorable PK/PD Profile

CS5007 demonstrated a superior pharmacokinetics (PK) / Pharmacodynamics (PD) profile compared to BL-B01D1 in the FaDu CDX model:

Greater potency: At 5 mg/kg, exposure (AUC) was comparable between the two ADCs, but tumor regression in the CS5007 group was significantly greater than that in the BL-B01D1 group (p < 0.05).
Longer half-life: CS5007 maintained a half-life of approximately 20 hours across dose levels, compared to approximately 10 hours for BL-B01D1 at 5 mg/kg.
8. Favorable Safety and Tolerability

In non-human primates (NHPs), CS5007 demonstrated favorable metabolic stability consistent with other EGFR-targeting agents, with a half-life of approximately 2 days. In human FcRn transgenic mice, the half-life was approximately 2.5–8 days.
Controllable toxicity: GLP toxicology studies determined the highest non-severe toxic dose (HNSTD) to be 30 mg/kg.
Safety window: No lethal toxicity was observed. Skin toxicity occurred only at the high-dose level. Overall, the safety profile appears manageable with a broad therapeutic window.

9. Phase I Clinical Trial Plan

CStone plans to initiate the Investigational New Drug (IND) application for CS5007 in the first half of 2026. The planned CS5007-101 study will be a monotherapy dose-escalation and expansion study designed to evaluate safety and recommended phase II dose (RP2D) in patients with advanced solid tumors. The study plans to enroll approximately 70 adult patients with advanced solid tumors who have progressed on or are ineligible for standard treatment or have no effective treatment options.

In summary, CS5007 is a highly promising bispecific ADC that demonstrates potent anti-tumor activity alongside a favorable safety and PK profile. Preclinical findings indicate that CS5007 binds with exceptional affinity, triggers rapid internalization across tumors with diverse EGFR and HER3 expression, effectively blocks dual downstream signaling pathways, and exhibits robust bystander-mediated tumor growth inhibition. These data provide a strong rationale to advance CS5007 into clinical investigation in solid tumors.

CS5006 – ITGB4 Targeting ADC

Integrin β4 (ITGB4) exclusively pairs with Integrin α6 (ITGA6) to form the α6β4 heterodimer, a receptor for the basement membrane protein laminin. ITGB4 is highly expressed on the surface of various solid tumors, including CRC, NSCLC, HNSCC and ESCC, while its expression in normal tissues is low. Distinct from other β integrins, ITGB4 features a unique 1,000-amino acid cytoplasmic domain that may facilitate a rapid antigen turnover. Furthermore, ITGB4 integrates with and amplifies key signaling cascades—including ErbB2, PI3K, FAK/Akt, and c-Met—thereby driving tumor progression. It also upregulates the expression of PD-L1 and mediates anti-PD-1 resistance via MEK/ERK signaling.

CS5006 is a novel ADC targeting ITGB4, composed of a humanized anti-ITGB4 IgG1 antibody conjugated via a highly stable, hydrophilic CSL20 linker (with tandem-cleavage technology) to a clinically validated exatecan payload, with an average DAR of 4.

Key Highlights:

1. Superior Molecular Stability

The linker-payload system of CS5006 demonstrates superior in vitro plasma stability to GGFG-DXd-based model ADCs targeting ITGB4, with less than 0.6% free payload released after 7 days of incubation in human or monkey serum, indicating a low risk of off-target toxicity.

2. Rapid and Deep Internalization

CS5006 triggers rapid and deep internalization on ITGB4-positive tumor cells.

3. Potent and Specific In Vitro Anti-tumor Activity

CS5006 exhibits nanomolar-level, antigen-dependent cytotoxic activity against tumor cell lines with high ITGB4 expression and sensitivity to exatecan in vitro. Its killing potency is significantly positively correlated with the expression level of ITGB4 on the tumor cell surface.

4. Significant Bystander Killing Effect

CS5006 demonstrates an excellent bystander killing effect. Supernatants from ITGB4-positive tumor cells incubated with CS5006 induced significant cytotoxicity in ITGB4-negative tumor cells.

5. Broad-Spectrum and Deep In Vivo Anti-Tumor Activity

CS5006 demonstrated potent and broad-spectrum tumor growth inhibition (TGI) activity in CDX models covering multiple tumor types, including NSCLC, BC, CRC, SCCHN, urothelial cancer (UC), ESCC, and gastric cancer (GC).

6. Favorable PK Profile and Safety

In NHPs, CS5006 exhibits a favorable PK and safety profile, with a half-life of approximately 3.5 days and a tentative HNSTD of 45 mg/kg.

CS5006 is a highly promising first-in-class ADC targeting ITGB4, combining broad-spectrum and potent anti-tumor activity with favorable safety and PK profiles. Preclinical studies have demonstrated rapid, deep internalization and potent, specific killing of ITGB4-positive cells, with bystander-mediated elimination of ITGB4-negative cells, thereby exhibiting broad-spectrum and robust in vivo anti-tumor activity in xenograft models. In NHPs, CS5006 exhibits a favorable HNSTD and half-life. Furthermore, it also demonstrates impressive CMC profiles, including high antibody yield, strong ADC stability, and favorable developability. Collectively, the preclinical data provide strong support for the clinical development of CS5006.

CStone expects to initiate the IND application for CS5006 in the second half of 2026.

CS5008 – SSTR2/DLL3 Bispecific ADC

DLL3 and SSTR2 are both highly overexpressed in small cell lung cancer (SCLC) and neuroendocrine tumors/carcinomas (NETs/NECs). DLL3 is overexpressed in more than 70% of SCLC and 64% of NECs patients, while SSTR2 is overexpressed in over 50% of SCLC and approximately 90% of G1/G2 NETs patients Therefore, dual targeting of SSTR2 and DLL3 holds great promise for overcoming intra- and inter-tumoral heterogeneity in SCLC and NETs/NECs, potentially improving efficacy and broadening the addressable patient population. Despite initial high sensitivity to chemotherapy and/or radiotherapy, most SCLC patients develop therapeutic resistance within one year. Accumulating evidence highlights that the heterogeneity and plasticity of SCLC are closely associated with the development of distant metastases and chemoresistance, which remain major obstacles to improving clinical outcomes.

CS5008 is a bispecific ADC constructed with: 1) an anti-DLL3 and SSTR2 human IgG1 antibody; 2) CStone proprietary hydrophilic CSL20 linker; 3) exatecan (Exa) as payload, conjugated with a DAR of approximately 4.

Key Highlights:

1. Excellent In Vitro Serum Stability

CS5008 demonstrated excellent stability in both human and cynomolgus monkey serum. After 7 days of incubation at 37°C, the toxin release rate was below 0.5%.

2. Rapid and Deep Internalization

CS5008 triggers rapid and deep internalization on SSTR2- and/or DLL3-positive tumor cells.

Specificity: In transgenic cells overexpressing DLL3 or SSTR2, CS5008 and its antibody exhibited significant antigen-dependent internalization.
Superiority: In SCLC tumor cells, CS5008 and its antibody induced significantly higher rates of internalization compared to their mono-specific ADC counterparts.
3. Potent and Antigen-Dependent In Vitro Killing Activity

CS5008 efficiently and specifically kills tumor cells expressing DLL3 or SSTR2 antigens, and the killing effect is significantly positively correlated with the expression level of the antigens (SSTR2+DLL3).

4. Broad-Spectrum and Potent In Vivo Anti-Tumor Activity

In SCLC CDX models, CS5008 demonstrated potent and broad-spectrum anti-tumor effects. A single dose induced tumor regression in various tumor models with different antigen expression levels. Notably, CS5008 outperformed DLL3-CSL20-Exa in the H446 (DLL3 negative SCLC) CDX model, indicating its potential to overcome tumor heterogeneity.

5. Favorable PK and Safety Profile

CS5008 exhibited a favorable PK profile in cynomolgus monkeys:

Long half-life: Approximately 14 days, indicating good stability.
Broad safety window: Provisional HNSTD of 60 mg/kg, with no lethal toxicity observed.
6. Potential New Strategy to Overcome Subtype Switching Resistance

By simultaneously targeting both antigens, CS5008 can effectively address the resistance challenge induced by treatment-driven molecular subtype switching in SCLC (e.g., from SCLC-A to SCLC-N).*

Subtype switching occurred in ~50% of patients during therapy.[1]
Recent data: 75% (3/4) of SCLC-A converted to SCLC-N vs. 100% (2/2) of SCLC-N stability.[1]
SCLC-N exhibits NEUROD1-driven SSTR2 overexpression.[1], [2]
A bispecific DLL3/SSTR2-ADC may therefore offer a promising strategy to overcome resistance resulting from therapy-induced subtype switching.
Notes. *: Yoshida T. WCLC, 2025; 1: Chiang CL et al. Lung Cancer. 2024 Feb; 2: Heeke S et al. Cancer Cell. 2024 Feb

CS5008 is a highly promising bispecific ADC with broad-spectrum, potent anti-tumor activity and favorable safety and PK profiles. Preclinical studies demonstrate that via rapid and deep internalization, CS5008 enables efficient and specific killing of tumor cells with varying DLL3 and SSTR2 expression and exhibits broad, robust in vivo anti-tumor activity in xenograft models. In NHPs, CS5008 displays favorable tolerability and excellent PK properties. Furthermore, CS5008 features high antibody yield, strong ADC stability, and good developability. Collectively, these data support advancing CS5008 into IND-enabling studies and subsequent clinical evaluation for solid tumors including SCLC, NECs, etc.

CStone plans to initiate the IND application for CS5008 in the second half of 2026.

(Press release, CStone Pharmaceauticals, APR 19, 2026, View Source [SID1234664522])

On April 19, 2026 Molecular Partners AG (SIX: MOLN; NASDAQ: MOLN), a clinical-stage biotech company developing a novel class of custom-built protein drugs known as DARPin therapeutics ("Molecular Partners" or the "Company"), reported the presentation of new preclinical data across three posters at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2026.

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The first poster outlines preclinical data supporting proof-of-concept for MP0632, a logic-gated Switch-DARPin CD3 T cell engager with CD2 co-stimulation designed to selectively kill cells co-expressing mesothelin (MSLN) and epithelial cell adhesion molecule (EpCAM). MP0632 leads to regression of established tumors expressing both EpCAM and MSLN, with minimal impact on tumors expressing only one antigen, indicating a favorable therapeutic window. In addition, the Switch-DARPin candidate allowed for safe use of potent costimulation for efficient tumor cell killing with low cytokine release profile. The data support MP0632’s potential as clinical lead candidate for the treatment of ovarian cancer and other MSLN- and EpCAM-positive solid tumors.

"We are excited to present new data on MP0632, our first logic-gated T cell engager candidate leveraging our Switch-DARPin technology. We designed MP0632 to achieve potent yet safe tumor-localized immune activation through incorporation of CD2 costimulation and through unmasking of the CD3 binder upon binding to two co-expressed tumor antigens – MSLN and EpCAM. We are looking forward to advancing MP0632 and building on the strong preclinical data package, which indicates its potential to make a difference to cancer patients," said Martin Steegmaier, Ph.D., CSO of Molecular Partners.

The second poster presents a computational workflow to identify and prioritize tumor-associated antigen pairs for improved tumor-selectivity and safety in support of designing novel Switch-DARPin candidates, such as MP0632. This scalable, data-driven platform provides a strong foundation for the discovery of next-generation multispecific immunotherapies. This workflow could also be leveraged for the identification of complementary tumor antigen pairs to address heterogeneous tumors, which could enable the design of next-generation multispecific Radio-DARPin candidates.

The third poster outlines the molecular characteristics of MP0712, the Company’s first 212Pb-based Radio-DARPin candidate, with high affinity binding to DLL3 and optimized half-life extended properties. MP0712’s properties are hypothesized to facilitate sustained tumor uptake through repeated DLL3 internalization-replenishment despite low cell surface density of the target, thereby supporting the attractive biodistribution profile of MP0712 observed in preclinical studies as well as in first patient imaging data from a Named Patient Access Program in South Africa using MP0712 with 203Pb.

MP0712, co-developed with strategic partner Orano Med, is evaluated in an ongoing Phase 1/2a trial in the US for the treatment of patients with small cell lung cancer (SCLC) and other DLL3-expressing neuroendocrine cancers.

Details of the presentations at AACR (Free AACR Whitepaper) 2026:

Logic-gated Switch-DARPin T cell engager with CD2 co-stimulation for improved safety and efficacy in MSLN and EpCAM co-expressing ovarian cancer
Session Category: Immunology
Session Title: T Cell Engagers 1
Session Start: 4/20/2026 9:00 AM PT
Session End: 4/20/2026 12:00 PM PT
Location: Poster Section 10
Poster Board Number: 16
Poster Number: 1624

Logic-gated Switch-DARPin–based immune cell engagers guided by data-driven tumor-antigen profiling: A computational workflow for the development of cancer immunotherapies
Session Category: Bioinformatics / Computational Biology / Systems Biology / Convergent Science
Session Title: Application of Bioinformatics to Cancer Biology 3
Session Start: 4/20/2026 2:00 PM PT
Session End: 4/20/2026 5:00 PM PT
Location: Poster Section 1
Poster Board Number: 16
Poster Number: 2691

Molecular characteristics of MP0712, a clinical stage ²¹²Pb-based Radio-DARPin candidate for targeted anti-DLL3 radiotherapy of small cell lung cancer (SCLC)
Session Category: Experimental and Molecular Therapeutics
Session Title: Targeted Radiopharmaceuticals and Combination Strategies in Cancer Therapy
Session Start: 4/22/2026 9:00 AM PT
Session End: 4/22/2026 12:00 PM PT
Location: Poster Section 17
Poster Board Number: 16
Poster Number: 7197

The posters will be made available on Molecular Partners’ website after the presentations.

(Press release, Molecular Partners, APR 19, 2026, View Source [SID1234664521])

On April 19, 2026 Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs), reported promising preclinical data across its pipeline of next- generation ADCs in five posters and one oral presentation at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2026. Of note, results from a preclinical study of STRO-004, its DAR8 Topo1 ADC targeting Tissue Factor (TF), were reviewed today in an oral presentation titled "STRO-004, an exatecan-based next-generation tissue factor (TF)-targeted ADC, demonstrates superior efficacy across TF-expressing solid tumors in a comprehensive single-mouse PDX trial."

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In the preclinical study, STRO-004 demonstrated robust and consistent antitumor activity across a broad range of TF-expressing solid tumor patient-derived xenograft (PDX) models, with improved efficacy compared to benchmark ADCs. At a single, clinically relevant dose of 5 mg/kg, STRO-004 achieved remarkable disease control and tumor reduction across multiple tumor types. STRO-004’s favorable tolerability, with a highest non-severely toxic dose (HNSTD) of 50 mg/kg, and pharmacokinetic profile are expected to enable increased drug exposure and payload delivery, supporting the Company’s belief that STRO-004 will demonstrate superior depth and durability of response in the clinic. Exploratory biomarker analyses provide preliminary insight into STRO-004’s mechanism of action, suggesting potential for combination studies addressing specific indications in either early or late lines of treatment.

"The STRO-004 preclinical data presented today underscore the potential of our next-generation ADCs to drive meaningful activity across multiple solid tumors," said Jane Chung, Sutro’s Chief Executive Officer. "As STRO-004 advances in the clinic – with initial results from our Phase 1 study expected in mid-2026 – these preclinical data further strengthen our confidence in its potential across indications. More broadly, they underscore the versatility of our platform to generate differentiated ADCs across many targets and payloads, supporting a pipeline designed to address significant unmet need in cancer."

In addition to the oral presentation, Sutro will present multiple posters highlighting advances across its ADC pipeline and discovery platforms, the full details of which are included below.

Select Poster Highlights:

Preclinical data for STRO-006, an integrin β6-targeting ADC (DAR 8 exatecan), demonstrated robust, dose-dependent antitumor activity across multiple solid tumor models at a single, clinically relevant dose of 5 mg/kg, including non-small cell lung cancer (NSCLC) and head and neck cancers. The program also shows a favorable pharmacokinetic and tolerability profile, supporting its potential as a differentiated next-generation ADC with IND submission planned for 2026.
Preclinical data for STRO-227, a PTK7-targeting dual-payload ADC (DAR 10; 8 exatecan + 2 MMAE), demonstrated robust, dose-dependent antitumor activity across multiple solid tumor models, including breast, ovarian and NSCLC, with improved efficacy versus single-payload ADCs. The program also shows favorable pharmacokinetics, stable payload delivery, and tolerability comparable to benchmark ADCs, supporting the potential of its dual-payload design. These findings position STRO-227 as a differentiated ADC with broad applicability across solid tumors. Sutro expects to file an IND for STRO-227, its first wholly-owned dual-payload ADC, in late 2026.

Full Poster Presentation Details:

Poster: "Phase 1 open-label study to evaluate safety, pharmacokinetics, and preliminary anti-tumor activity of STRO-004 in adults with refractory/recurrent metastatic solid tumors"
Session Date and Time: Monday, April 20, 2026; 9:00 AM-12:00 PM PT
Poster: "STRO-006: An Integrin beta-6–targeting ADC demonstrates favorable safety profile and potent antitumor activity in preclinical solid tumors"
Session Date and Time: Monday, April 20, 2026; 9:00 AM-12:00 PM PT
Poster: "Preclinical characterization of STRO-227: A PTK7-targeting dual-payload ADC with topoisomerase 1 and tubulin inhibitors"
Session Date and Time: Monday, April 20, 2026; 9:00 AM-12:00 PM PT
Poster: "The HER2-targeting dual-payload antibody-drug conjugate combining a topoisomerase I inhibitor and a microtubule inhibitor demonstrates superior efficacy and overcomes resistance to single-payload ADCs in xenograft models"
Session Date and Time: Monday, April 20, 2026; 9:00 AM-12:00 PM PT
Poster: "Sutro’s Site-Specific Dual-Payload ADCs Combining TOPO1i and DNA Damage Response Inhibitors to Enhance Efficacy, Overcome Resistance, and Improve Safety"
Session Date and Time: Tuesday, April 21, 2026; 9:00 AM-12:00 PM PT

In addition to these presentations, Sutro’s strategic partner, Astellas Pharma, also reviewed preclinical results from its TROP2-targeted iADC program at AACR (Free AACR Whitepaper) today. The oral presentation, titled "ASP2998, a TROP2-targeted immunostimulatory antibody-drug conjugate (iADC) with dual payloads, demonstrates potent efficacy and a favorable safety profile in nonclinical models," highlighted the company’s progress in the development of next-generation iADCs leveraging Sutro’s cell-free protein synthesis platform. ASP2998 is a first-in-class iADC that combines cytotoxic and immune-stimulatory mechanisms to enhance antitumor efficacy. Inclusion of a STING agonist augments the antitumor efficacy, immune activation and durable tumor immunity of ASP2998, supporting its superior activity over toxin-only anti-TROP2 ADCs. Preclinically, ASP2998 demonstrated a favorable safety profile, supporting a promising therapeutic index. ASP2998 entered the clinic earlier this year and is actively dosing patients.

Following the congress, the Company’s presentations will be made available in the Scientific Publications section of Sutro Biopharma’s website at www.sutrobio.com.

(Press release, Sutro Biopharma, APR 19, 2026, View Source [SID1234664520])

On April 19, 2026 Revolution Medicines, Inc. (Nasdaq: RVMD), a late-stage clinical oncology company developing targeted therapies for patients with RAS-addicted cancers, reported updated Phase 1 (RMC-9805-001) clinical data for zoldonrasib, an oral RAS(ON) G12D-selective inhibitor, in patients with previously treated KRAS G12D non-small cell lung cancer (NSCLC). Results were highlighted in the official press program at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting and will be featured in a plenary oral presentation today, April 19, 2026, at 1:30 p.m. PDT.

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"Patients with RAS G12D non-small cell lung cancer remain a population with a significant unmet medical need for targeted therapeutic options," said Jonathan Riess M.D., medical director of thoracic oncology at UC Davis Comprehensive Cancer Center and principal investigator for the RMC-9805-001 trial. "The manageable safety profile and evidence of clinical activity in this Phase 1 trial are encouraging and support the continued clinical development of zoldonrasib."

"We believe these updated data further strengthen the profile of zoldonrasib as a potentially important targeted therapy for patients with RAS G12D non-small cell lung cancer where historical treatment options, such as chemotherapy, have offered limited benefit, and are often associated with considerable toxicity," said Alan Sandler, M.D., chief development officer of Revolution Medicines. "The emerging profile supports advancing zoldonrasib across monotherapy and combination settings in lung cancer and other RAS G12D-driven cancers."

Summary of Phase 1 Zoldonrasib Data at AACR (Free AACR Whitepaper) 2026 (Abstract # CT021)

RMC-9805-001 is a multicenter, open-label, dose escalation and dose expansion Phase 1 trial designed to evaluate zoldonrasib in patients with advanced solid tumors harboring a KRAS G12D mutation. The data to be presented at the AACR (Free AACR Whitepaper) Annual Meeting are as of a December 1, 2025 data cutoff, and included 40 patients with KRAS G12D NSCLC treated with zoldonrasib 1200 mg once daily, the recommended Phase 2 dose, and who were evaluable for safety. Efficacy analyses were conducted in a subset of patients with prior immune checkpoint inhibitor and platinum chemotherapy and no prior docetaxel treatment who had sufficient follow-up for response assessment (n=27).

Zoldonrasib was generally well tolerated and demonstrated a safety profile consistent with previously reported findings. Treatment-related adverse events (TRAEs) of any grade occurring in at least 15% of patients were nausea (43%), vomiting (33%), diarrhea (30%), and rash (18%). The majority of TRAEs were Grade 1 in severity. Grade 3 TRAEs occurred in 13% of patients and resolved following dose interruption; TRAEs led to treatment discontinuation in 5% of patients. No Grade 4 or Grade 5 TRAEs were observed. Zoldonrasib demonstrated a favorable mean dose intensity of 94%.

Zoldonrasib demonstrated encouraging clinical activity in patients with KRAS G12D NSCLC previously treated with immune checkpoint inhibitor and platinum chemotherapy and no prior docetaxel. Among this subset of patients (n=27), the confirmed objective response rate was 52% (confidence interval (CI): 32, 71) and the disease control rate was 93% (CI: 76, 99). Median time to response was 1.4 months and median duration of response was not yet estimable (95% CI: 8.3, not estimable). Median progression-free survival (PFS) was 11.1 months (95% CI: 5.3, not estimable), with an estimated 12-month PFS rate of 48% (95% CI: 27, 66). Overall survival (OS) data were immature at the time of analysis, and median OS was not yet reached with median potential follow-up of 13.1 months (range: 9.1–19.9). Estimated survival rate at 12 months was 73% (95% CI: 52, 86), suggesting encouraging early survival outcomes.

About Non-Small Cell Lung Cancer
Non-small cell lung cancer (NSCLC) accounts for 80%-85% of all lung cancers, with more than 229,000 people diagnosed in the U.S. each year.1,2 Despite treatment advancements, NSCLC remains a leading cause of cancer-related mortality worldwide, primarily due to its late-stage diagnosis and limited response to conventional therapies. KRAS G12D is the most common oncogenic driver of human cancers and represents 4% of NSCLC cases.3

About Zoldonrasib
Zoldonrasib is a tri-complex inhibitor that binds to cyclophilin A, creating a complex that selectively recognizes and inhibits the active, oncogenic RAS G12D(ON) mutant. KRAS G12D is the most prevalent RAS mutation, accounting for 29% of all RAS cancers, and currently lacks an approved targeted therapy.4 Across tumor types, approximately 61,000 new patients with RAS G12D cancers are estimated each year in the United States.5 Zoldonrasib is currently being evaluated as a monotherapy and in combination with other therapies, including with Revolution Medicines’ RAS(ON) multi-selective inhibitor daraxonrasib (RMC-6236), as well as standard of care regimens in lung and gastrointestinal cancers.

(Press release, Revolution Medicines, APR 19, 2026, View Source [SID1234664519])

On April 18, 2026 Pliant Therapeutics, Inc. (Nasdaq: PLRX) reported the presentation of updated data from its Phase 1 trial of PLN-101095, in combination with pembrolizumab, in patients with immune checkpoint inhibitor (ICI)-refractory advanced or metastatic solid tumors. The oral presentation was made at the Clinical Trials Mini Symposium of the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2026 Annual Meeting.

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Timothy A. Yap, MBBS, Ph.D., Medical Oncologist and Physician-Scientist at the University of Texas MD Anderson Cancer Center, presented results from the dose escalation portion of the ongoing Phase 1a/1b trial covering data as of February 27, 2026. Results showed that in the heavily pretreated ICI-secondary refractory patient subgroup, twice daily (BID) treatment with PLN-101095 at the highest doses in combination with the ICI pembrolizumab showed antitumor activity. One confirmed overall complete response, two confirmed overall partial responses, including one patient with a complete response of baseline target lesions, and one unconfirmed partial response were reported in patients with cholangiocarcinoma, non-small cell lung cancer (NSCLC), melanoma and head and neck squamous cell carcinoma, respectively. As of the data cutoff date, the median time on treatment for the three confirmed responders was 19 months, who experienced an average baseline target tumor reduction of 89%.

All responding patients showed large increases (4- to 13-fold vs. baseline) in plasma interferon gamma (IFN-γ) after a 14-day run-in period of monotherapy with PLN-101095. At Week 10, all responders maintained more than a 2-fold increase in IFN-γ. No non-responders showed meaningful increases in IFN- γ. In addition to IFN- γ increases, all responding patients showed elevated plasma PD-L1 levels, known to be induced by increased IFN-γ and a predictor of an improved ICI response. As increases in IFN-γ have the potential to serve as a biomarker of TGF-β inhibition and an early indicator of PLN-101095 anti-tumor activity. Pliant anticipates further study of this biomarker as part of the expansion cohorts in the Phase 1b trial.

PLN-101095 was generally well tolerated across all doses evaluated with few discontinuations (n=2) due to adverse events. Rash was the most common treatment-related adverse event (TRAE), all Grade 1 or 2, and the majority of events occurred within the first 2 days of the initial pembrolizumab dose. One Grade 3 TRAE was observed.

PLN-101095 demonstrated a dose-ordered exposure at Day 14 with doses ≥1000 mg BID achieving sustained IC90 coverage and all participants dosed at ≥1000 mg BID maintaining IC75 coverage over 24 hours. These results support the consistent target engagement of PLN-101095.

Sixteen patients with ten different tumor types, including both primary and secondary refractory patients, were enrolled in five dose cohorts. Patients were treated for 14 days with PLN-101095 monotherapy administered orally at doses of 250 mg twice a day (BID) (n=1), 500 mg BID (n=2), 1000 mg BID (n=6), 1000 mg three times a day (TID) (n=4) or 2000 mg BID (n=3), followed by the addition of pembrolizumab at 200 mg administered intravenously every three weeks until disease progression. Scans were conducted at baseline, Day 14, Week 10, and every 8 weeks thereafter.

Dr. Yap commented "One of the ways that the tumor microenvironment can suppress responses to immune checkpoint inhibitors is through a process that is activated by integrins to upregulate TGF-β. PLN-101095 is designed to inhibit the integrins before they can ever do that, which gives it significant potential to stimulate or reinvigorate the immune response to cancer. These clinical trial data, for the combination of PLN-101095 and pembrolizumab in patients with secondary immune checkpoint inhibitor resistance, show the potential to meet a high unmet therapeutic need."

"These encouraging results show a deepening of baseline tumor reductions in confirmed responders and an increased median time on treatment with PLN-101095 in patients with difficult-to-treat ICI refractory tumors," said Bernard Coulie, M.D., PhD., Chief Executive Officer of Pliant. "We have initiated the Phase 1b trial to expand this novel combination therapy in specific tumor types to address patients in need and deliver value to our investors."

Slides accompanying these data can be found here and under the Investors & Media page of Pliant’s website at www.PliantRx.com.

PLN-101095 Phase 1b Indication Expansion Trial

Pliant has initiated a Phase 1b open-label indication expansion trial enrolling three cohorts of patients with NSCLC, tumors with high tumor mutational burden or clear cell renal cell carcinoma. Patients will be treated for 14 days with PLN-101095 dosed at 1,000 mg twice daily as monotherapy, after which pembrolizumab will be added as combination therapy. Enrollment is underway with interim data expected in 2027.

PLN-101095 for the Treatment of Checkpoint Resistant Tumors

PLN-101095 is an oral, small molecule inhibitor of integrins αvβ8 and αvβ1. PLN-101095 is being evaluated in Phase 1a/1b open-label, dose-escalation and indication expansion trial to evaluate the safety, tolerability, pharmacokinetics, and preliminary evidence of antitumor activity of PLN-101095 in combination with pembrolizumab, in patients with immune checkpoint inhibitor (ICI)-refractory advanced or metastatic solid tumors. Activated transforming growth factor-β (TGF-β) has been shown to foster an immuno-suppressive tumor microenvironment (TME) that contributes to immune-checkpoint inhibitor (ICI) resistance and treatment failure in cancer.1 Blocking integrins αvβ8 and αvβ1 has been shown to prevent the activation of TGF-β and is expected to stimulate immune activation by increasing immune cell infiltration into the tumor microenvironment.2,3 PLN-101095 in combination with an anti-PD-1 monoclonal antibody (mAb) elicited a dose-dependent reduction in tumor volume and increased CD8+ T cell tumor infiltration in the tumor microenvironment compared with anti-PD-1 mAb therapy alone.4 In preclinical studies, PLN-101095 demonstrated monotherapy activity in reduction of tumor volume and increased cluster of differentiation (CD)8+ T cell infiltration.

(Press release, Pliant Therapeutics, APR 18, 2026, View Source [SID1234664529])