On April 16, 2024 TScan Therapeutics, Inc. (Nasdaq: TCRX), a clinical-stage biopharmaceutical company focused on the development of T cell receptor (TCR)-engineered T cell therapies (TCR-T) for the treatment of patients with cancer, reported an update on its solid tumor and heme malignancies clinical programs (Press release, TScan Therapeutics, APR 16, 2024, View Source [SID1234642101]).

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"We continue to make meaningful progress across both our solid tumor and heme malignancies Phase 1 clinical programs. As we rapidly approach dosing the first patients in the solid tumor program, I am pleased to share that over 40 patients have completed all biomarker testing in the screening protocol, with the majority qualifying for at least one TCR-T in our ImmunoBank and many qualifying for multiplex therapy. This should allow for rapid enrollment into the treatment protocol over the course of the year," said Gavin MacBeath, Ph.D., Chief Executive Officer. "With respect to the heme program, we are encouraged to see continued positive data with all treatment-arm patients remaining relapse-free with no detectable cancer to date, now with a median follow-up of over 10 months."

Solid Tumor Program: TScan continues to expand the ImmunoBank, a collection of therapeutic TCR-Ts that target different cancer-associated antigens presented on diverse HLA types. TScan’s strategy is to treat patients with multiple TCR-Ts to overcome tumor heterogeneity and prevent resistance that may arise from either target or HLA loss (screening protocol: NCT05812027; treatment protocol: NCT05973487).

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Phase 1 solid tumor clinical study has been initiated; first three patients expected to be dosed in early May 2024.

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More than 40 patients have completed all biomarker testing in the screening protocol across a broad array of tumor types. 60% of patients qualify for at least one TCR-T in the ImmunoBank and approximately 30% are eligible for multiplex therapy (T-Plex), potentially enabling rapid enrollment into the treatment protocol upon disease progression.

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Patients have been identified across all six TCR-T cohorts with dosing expected to commence early May.

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Initial data on patients from both singleplex and multiplex cohorts expected in the second half of 2024.

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Additional IND filings planned to continue to expand the ImmunoBank.

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Long-term duration of response data for multiplex therapy anticipated in 2025.

Heme Malignancies Program: TScan’s two lead TCR-T cell therapy candidates, TSC-100 and TSC-101, are designed to treat residual disease and prevent relapse in patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndromes (MDS) undergoing allogeneic hematopoietic cell transplantation (HCT) (NCT05473910).

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All eight patients treated with TSC-100 or TSC-101 remain MRD negative, relapse-free with no detectable cancer to date in either bone marrow biopsies or peripheral blood (median follow-up of >10 months) and no dose limiting toxicities observed to date.

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To date, all but one patient has exhibited complete donor chimerism in all subsets of blood cells at all time-points, indicating that only donor-derived cells are present in these patients following treatment with either TSC-100 or TSC-101. One patient with T-ALL who was treated with TSC-100 at the lowest dose level exhibited minimally detectable (<0.3%) mixed donor chimerism at 10.5 months and 12 months post-transplant.

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No detectable mixed chimerism was observed in the malignant cell lineage (CD3+ T-cells) for this patient; mixed chimerism was only observed in healthy nonmalignant blood cells (CD33+ myeloid cells)

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In contrast, for the control arm (transplant alone), eight patients have now been enrolled and only one has achieved and maintained complete donor chimerism to date. Two patients relapsed approximate six months post-transplant and one of these patients died approximately three months later. A third patient required clinical intervention on day 133 because of concerns of impending relapse, and a fourth died 21 days post-transplant.

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Opening of expansion cohorts at the recommended Phase 2 dose level to further characterize safety and evaluate translational and efficacy endpoints is planned for the third quarter of 2024.

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Completion of Phase 1 enrollment and reporting of one-year clinical and translational data on initial patients is anticipated in the second half of 2024.

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Expects to initiate registration trial pending feedback from regulatory authorities and report two-year relapse data in 2025.