Positive phase 1/2 data for CS2009; Goldman Sachs reiterates Buy on CStone Pharma

Overview

This report is Goldman Sachs' company research on CStone Pharma following the ASCO 2026 update for CS2009. The core conclusion is that CS2009, as a PD-1/VEGF/CTLA-4 trispecific antibody, has provided stronger evidence in mature phase 1 safety, early phase 2 efficacy in NSCLC, and response rates across multiple cold tumors; management plans to hold a Type B meeting with the FDA in 4Q26 and launch the first two phase 3 MRCTs before the end of 2026, with another two trials planned to start in 1Q27.

Core views

Goldman Sachs maintains a positive view, believing the current data for CS2009 support its therapeutic feasibility and differentiation potential. The report emphasizes that phase 1 data reinforced overall tolerability, while phase 2 NSCLC data showed competitive ORR in PD-L1-positive, PD-L1-negative/low-expression squamous, and later-line previously treated populations. At the same time, despite ivonesicmab achieving strong OS benefit in HARMONi-6, Goldman Sachs still expects CS2009's regulatory path in AGA-negative NSCLC to remain intact, with the key point being that the launch timing of CS2009's pivotal trials may precede the earliest possible approval timing of the competing product in 1L NSCLC.

Analysis framework

The report mainly uses clinical data interpretation, peer therapy benchmarking, regulatory timeline projection, and risk-adjusted DCF valuation. On the clinical side, it focuses on ORR, safety, and the maturity of patient follow-up; on the competitive side, it compares CS2009 with pembrolizumab, PD-1/VEGF bispecific antibodies, and ivonesicmab-related trials; on the valuation side, it uses a 12-month risk-adjusted DCF framework.

Methodology notes

• Valuation methodsRisk-adjusted DCF

  Adjust future cash flows by the probability of clinical success

  Goldman Sachs' 12-month target price of HK$9.44 is based on a 14.5% discount rate, a 2% perpetual growth rate, and PoS adjusted by average industry success rates across different R&D stages combined with existing clinical data.

• Clinical data analysisORR and safety comparison

  Use objective response rate and adverse events to assess early efficacy and tolerability

  The report compares CS2009's ORR and G3+ adverse events in NSCLC, mCRC, STS, and nccRCC against existing PD-1/VEGF therapies, pembrolizumab, and standard treatments.

• Regulatory path assessmentPivotal trial and competitor timeline projection

  Determine active-control requirements through trial initiation, readout, and potential approval timing

  The report believes that if CS2009 enters pivotal trials as planned between 4Q26 and 1Q27, its trial initiation timing would precede the earliest possible approval timing for ivonesicmab in 1L NSCLC, meaning a pembrolizumab regimen may still serve as the active control.

Asset mapping & comparison

Structured mapping from thesis to named assets (strengths, weaknesses, peers, risks).

• CStone Pharma（02616.HK）

  Covered company

  Strengths

  Owns innovative oncology immunotherapy pipelines including CS2009; Goldman Sachs reiterates Buy and assigns a target price of HK$9.44.

  Weaknesses

  Limited commercialization track record and still needs to prove late-stage clinical execution and sales ramp-up capability.

  Comparison

  Relative to China's innovative drug peers, the investment thesis is more concentrated on CS2009's differentiated mechanism and global phase 3 advancement.

  Risks

  R&D failure, financing pressure, competition in China's IO market, and talent recruitment and retention risks.

• CS2009

  Core clinical asset

  Strengths

  The PD-1/VEGF/CTLA-4 trispecific antibody design has shown preliminarily high ORR in NSCLC and cold tumors, while safety data remain manageable after follow-up.

  Weaknesses

  Sample size remains small, follow-up duration is short in some cohorts, and phase 3 data are still needed to validate OS, PFS, and tolerability.

  Comparison

  ORR in 1L PD-L1-positive NSCLC is 81.3%, which the report says is competitive versus 60%-77% for PD-1/VEGF bispecific antibodies and about 45% for pembrolizumab.

  Risks

  If competitors establish a new standard earlier, regulators may raise control-arm requirements; there are also execution risks around phase 3 enrollment and CMC preparation.

• ivonesicmab

  Key competitor and regulatory reference

  Strengths

  HARMONi-6 showed strong OS benefit in 1L squamous NSCLC, with OS HR of 0.66.

  Weaknesses

  HARMONi-3 in the more relevant mixed squamous/non-squamous 1L NSCLC population is still awaiting readout.

  Comparison

  Goldman Sachs believes HARMONi-3 is a more appropriate reference than HARMONi-6 for CS2009's first phase 3 plan in 1L NSCLC.

  Risks

  If HARMONi-3 data are significantly superior and change the clinical standard earlier, CS2009's future differentiation space may be compressed.

Key data

• Rating and target priceBuy; target price HK$9.4412-month risk-adjusted DCF target price.
• Reference price on disclosure pageHK$5.44According to company-specific disclosure text; corresponding to implied upside of approximately 73.5% versus the target price.
• Phase 1 safetyG3+ TRAE 24.6%; G3+ irAE 12.7%; G3+ VEGF-related TRAE 5.1%The report believes it continued to show sustained tolerability after longer follow-up.
• CTLA-4-related toxicityAny-grade rash 10.2%; ulcerative colitis 1%-2%, all grade 1-2Disclosed by management; the report believes toxicity control is good.
• 1L PD-L1-positive NSCLCORR 81.3% (13/16)The March update showed ORR of 90% in 10 patients, with all responders still maintaining response; follow-up was approximately 2 months.
• 1L PD-L1-negative/low-expression squamous NSCLCORR 75% with chemotherapy combination, N=8The report believes the sample size is small, but preliminarily shows potential in the low PD-L1 squamous subgroup.
• 2/3L I/O- and chemotherapy-treated NSCLCORR 66.7% with docetaxel combinationShows signs of improvement versus existing standard treatment with low double-digit ORR for docetaxel monotherapy.
• Cold tumor expansion signals1L mCRC with chemotherapy ORR 66.7%; 2L+ pMMR/MSS mCRC monotherapy ORR 25%; 2L+ STS monotherapy ORR 33.3%; 2L+ nccRCC monotherapy ORR 33.3%Supports CS2009's broad-spectrum therapeutic potential beyond NSCLC.
• Phase 3 MRCT planFDA Type B meeting in 4Q26; first two phase 3 trials to start before YE26; another two to start in 1Q27The company plans to prioritize 1L mCRC and other indications as one of its phase 3 directions.
• Competitor regulatory timelineivonesicmab HARMONi-6 OS HR 0.66; HARMONi-3 squamous cohort PFS/interim OS readout expected in 2H26, non-squamous PFS readout expected in 1H27Goldman Sachs estimates ivonesicmab could be approved in 1L NSCLC as early as 1H28, while other phase 3 PD-1/VEGF assets are mainly expected to complete in 2029 or later.

Impact & implications

If CS2009 data continue to mature and phase 3 MRCTs progress on schedule, CStone Pharma's core pipeline value and potential BD negotiating leverage could strengthen. Near-term share price volatility is affected by the strong OS data from ivonesicmab, but Goldman Sachs believes this does not materially undermine CS2009's key regulatory path. From an investment perspective, clinical execution, trial design, BD execution, and competitor readouts will determine the probability of target price realization.

Risks

• CS2009 is still in the early-to-mid clinical stage, with small sample size and short follow-up duration, and its efficacy and safety need phase 3 validation.
• The company lacks a sufficient commercialization track record, and there is uncertainty around the sales ramp-up of existing products.
• Competition in China's oncology immunotherapy market is intense, and PD-1/VEGF and related combination therapies may continue to raise the competitive bar.
• Sustained R&D investment requires capital support, and the financing environment may affect pipeline advancement.
• If competitor ivonesicmab or other PD-1/VEGF assets establish a new treatment standard earlier, the phase 3 design and regulatory comparator for CS2009 may face changes.
• There is uncertainty in R&D execution, CMC preparation, global MRCT enrollment progress, and BD negotiations.
• Talent recruitment and retention may affect R&D and commercialization execution.

What to watch

• Outcome of the FDA Type B meeting in 4Q26, including feedback on trial design and CMC preparation.
• Whether the first two phase 3 MRCTs can start as planned before YE26, and whether the subsequent two trials can be launched in 1Q27.
• Further maturation of phase 2 NSCLC data for CS2009 in terms of ORR, duration of response, PFS, and safety.
• Phase 3 design and enrollment pace for priority indications such as 1L mCRC and 2L AGA-negative NSCLC.
• Key readouts from HARMONi-3 in 2H26 and 1H27, as well as the potential approval timeline for ivonesicmab.
• Whether the company can complete a CS2009-related BD transaction before YE26.
• PoC data for early-stage assets such as CS5001 ROR1 ADC, and whether sales ramp-up of commercialized assets in China exceeds expectations.