ZLAB · Zai Lab

The thesis

Zai Lab's shares are modestly more likely than not to beat the S&P 500 over the next three months. The case rests on zoci, the company's DLL3-targeted cancer drug, and on management's commitment to start a global first-line Phase 3 trial by year-end 2026. A start announced by 31 December 2026 settles it. Product revenue is still below its level of a year earlier, so the valuation depends on the drug.

Zoci (zocilurtatug pelitecan) is an antibody-drug conjugate (ADC), an antibody that carries a toxic payload into cancer cells. On 23 October 2026 Zai Lab reported a confirmed objective response rate (ORR) of 81.8% (27 of 33 patients) for zoci plus atezolizumab in first-line extensive-stage small-cell lung cancer (ES-SCLC). The result comes from one 33-patient arm with no randomized comparison. The Phase 3 is the test of it.

The third-quarter release of 5 November 2026 commits to "initiate the global randomized Phase 3 study evaluating zoci 1.6 mg/kg in combination with PD-L1 inhibitors by year-end 2026". It also calls 2027 "a pivotal year, with a potential first U.S. BLA submission for zoci". A biologics license application (BLA) is the US filing for approval. Through 13 November 2026, company news has announced no zoci trial start since that release.

The rating is Medium because the Phase 3 timing is restated in writing, the October placement funds the program, and the American depositary shares (ADS) closed at $24.60 on 13 November 2026, still above the $22.04 per ADS that placement investors paid. The 13 November 2026 drop from $26.04 came on the day of non-oncology ZL-1503 data and did not change the zoci timeline.

Bullish and bearish views on Zai Lab Limited

The bull case on Zai Lab Limited (ZLAB), in brief: Phase 3 timing restated in writing. The bear case: product revenue still shrinking.

Bull case

• Phase 3 timing restated in writing. The 5 November 2026 release keeps the randomized global first-line ES-SCLC Phase 3 at year-end 2026. The trial is registered as NCT07796100.
• Response rate above standard care. The 81.8% confirmed ORR compares with the 60–70% ORR and roughly 5-month median progression-free survival (PFS) for checkpoint inhibitor plus chemotherapy that Zai Lab cited on 23 October 2026. Zoci-related side effects of grade 3 or higher occurred in 9.1% of patients (3 of 33).
• A larger epNEC dataset held up. At the NANETS 2026 symposium, zoci showed a 40% confirmed ORR and a 5.6-month median duration of response in 60 patients with previously treated extrapulmonary neuroendocrine carcinoma (epNEC), per GuruFocus on 5 November 2026. The rate was 38.2% in 34 patients in April 2026.
• Cash funds the global program. Cash, current restricted cash and short-term investments were $659.7 million at 30 September 2026, per the third-quarter release. That excludes about $241.2 million of net proceeds from the private placement that closed on 27 October 2026.
• A second global program reported clean data. On 13 November 2026 Zai Lab reported that a single dose of ZL-1503 of 200 mg or more held at least 90% inhibition of the IL-13 biomarker pSTAT6 through week 12 in healthy volunteers, with a half-life of about 40–50 days and no serious adverse events or anti-drug antibodies, per Benzinga. The company expects patient data in atopic dermatitis in the first half of 2027.
• Management keeps zoci in house. On the 5 November 2026 call, chief executive Samantha Du said the plan is to "advance the drug itself", with launch planning underway, per MarketBeat's call summary.

Bear case

• Product revenue still shrinking. Third-quarter 2026 product revenue was $107.6 million against $115.4 million a year earlier, up only 2% from the second quarter, per the 5 November 2026 release. Filed revenue fell from a year earlier in each of the first three quarters of 2026.
• Losses widened. The third-quarter net loss was $46.1 million against $36.0 million a year earlier, or $0.41 per ADS against $0.33, including a $13.6 million inventory write-down. Free cash flow over the four quarters to 30 September 2026 was −$163 million, per the 10-Q filed 5 November 2026.
• Gross margin has slipped. The filed gross margin was 52.6% in the quarter to 30 September 2026, against 61.5% in the quarter to 31 March 2026 and 59.7% a year earlier.
• Placement shares can come to market. Investors bought 11,340,000 ADSs at $22.04 in the placement that closed on 27 October 2026. Once Zai Lab's resale registration is effective, those shares trade freely while the price sits above what the buyers paid.
• Small first-line sample. The 81.8% ORR comes from 33 patients, and no PFS figure for the doublet has been reported as of 13 November 2026. Response rates in early single-arm cohorts often fall as follow-up lengthens.
• Tarlatamab sets the bar. Amgen's DLL3-targeted bispecific tarlatamab is already approved in previously treated small-cell lung cancer. Its move into earlier lines raises the standard zoci's randomized trials must clear.

Price setup

The ADS closed at $24.60 on 13 November 2026, down from $26.04 on 12 November 2026. That is 15.2% below the 52-week intraday high of $29.02, set on 9 November 2026, a session that closed at $26.86. The shares have closed lower in each session since that high. The 3-month change is −4.1%, measured from a $25.64 close on 17 August 2026.

On adjusted daily closes as of 13 November 2026, the last close sits at the 50-day moving average of $24.62 and above the 200-day moving average of $21.30. Below the price, the $22.60 close on 5 November 2026, before the quarterly report, and the $22.04 placement price set on 23 October 2026 mark where the earnings rise began and where about $250 million of new equity was priced. A common market view is that a recent placement price draws buyers on a decline; nothing in measured price history supports it as a rule. The 52-week closing low is $16.30, set on 2 February 2026.

The ADS rose from $22.60 on 5 November 2026 to $25.48 on 6 November 2026 after the quarterly report.

Catalysts ahead

• ~31 December 2026 (est.): End of the company's year-end 2026 window for starting the global first-line zoci Phase 3 (NCT07796100). A registrational start announced by this date confirms the timing management restated on 5 November 2026 and settles the case; no start by then breaks it.
• First half of 2027 (company guidance): Topline results from the single-arm zoci epNEC cohort. These results decide whether a first US accelerated-approval application for zoci can follow in 2027.
• First half of 2027 (company guidance): First ZL-1503 data in patients with moderate-to-severe atopic dermatitis. Shows whether the clean healthy-volunteer profile reported on 13 November 2026 carries into patients, giving the company a second global program beyond zoci.
• Second half of 2027 (company guidance): Potential interim analysis of the DLLEVATE Phase 3 in previously treated small-cell lung cancer. This is the first randomized test of zoci against chemotherapy and precedes a US accelerated-approval submission in that disease.

What would change the view

A weekly close below $22.00, under the $22.04 per-ADS price of the October 2026 private placement, which would show the market no longer paying for the zoci data. The case also fails if no global first-line zoci Phase 3 start is announced by 31 December 2026.

The risks this note tracks, each with what would confirm it:

• The first-line Phase 3 start slips past 2026. Confirmed by: no start announced by 31 December 2026, or management moving the randomized Phase 3 timing into 2027.
• Early response rates fail to hold as follow-up matures, weakening the first-line Phase 3 case. Confirmed by: updated doublet results showing median PFS near the roughly 5 months the company cites for chemo-immunotherapy.
• Greater China product revenue does not recover in 2027 as management expects. Confirmed by: quarterly product revenue in 2027 below the same quarter of 2026.
• Tarlatamab's progress sets a higher first-line bar and slows DLLEVATE enrollment. Confirmed by: regulatory approval of tarlatamab in first-line maintenance, or the company pushing the DLLEVATE interim analysis beyond the second half of 2027.
• Placement investors resell their ADSs once registration is effective, adding supply. Confirmed by: the resale registration statement for the 11,340,000 placement ADSs becoming effective, followed by placement buyers reporting reduced holdings in later 13G or 13F filings.
• The epNEC accelerated-approval route fails to deliver a first US filing in 2027. Confirmed by: first-half 2027 topline results below the 38.2% ORR reported in April 2026, or new FDA feedback requiring a randomized trial.

What it trades with

The ADS tracks the Hong Kong-listed ordinary shares (9688), so the Hong Kong session and China biotech sentiment set the tone before the US open. Effectively all product revenue comes from Greater China, which ties results to China's national reimbursement drug list (NRDL) pricing cycle and to licensed products such as argenx's Vyvgart and Novocure's Tumor Treating Fields. On zoci, the shares move with news on DLL3-targeted competitors, Amgen's tarlatamab first among them, and with small-cell lung cancer readouts at oncology meetings.

Single-stock outcomes over three months are wide. Across liquid US stocks, the standard deviation of 63-session returns was 27% in 2026, against 15% in 2017, so one company event can outweigh any broad market drift over the call's horizon.