Cullinan Therapeutics, Inc.

Item 7.01 Regulation FD Disclosure. On August 12, 2026, Cullinan Therapeutics, Inc. (the “Company”), together with Taiho Oncology, Inc. and Taiho Pharmaceutical Co., Ltd. (collectively “Taiho”), issued a press release announcing that its global Phase 3 clinical trial evaluating the combination of zipalertinib and platinum-based chemotherapy compared with chemotherapy alone in the first-line treatment of adult patients with previously untreated, locally advanced or metastatic non-small cell lung cancer (“NSCLC”) harboring epidermal growth factor receptor (“EGFR”) exon 20 insertion (“ex20ins”) mutations (the “REZILIENT3 clinical trial”) met its primary endpoint of progression-free survival ("PFS") at a planned interim analysis. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. The information in this report furnished pursuant to Item 7.01, including Exhibit 99.1 attached hereto, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 8.01 Other Events. On August 12, 2026, the Company and Taiho announced that the REZILIENT3 clinical trial met its primary endpoint of PFS at a planned interim analysis. In this analysis, the clinical trial demonstrated a statistically significant and clinically meaningful improvement in PFS in the zipalertinib containing arm. Observed safety for the zipalertinib containing arm was manageable. Based on these data, the Independent Data Monitoring Committee recommended unblinding the clinical trial. The clinical trial will continue to monitor efficacy and safety. Full results from the REZILIENT3 clinical trial will be submitted for presentation at an upcoming international medical conference. Based on these results, pending discussions with the U.S. Food and Drug Administration, Taiho and the Company plan to pursue U.S. regulatory approval for the combination of zipalertinib and platinum-based chemotherapy in the first-line treatment of adult patients with previously untreated, locally advanced or metastatic NSCLC harboring EGFR ex20ins mutations in the first-line setting.