The trouble with sending T cells after a T-cell cancer is that the hunters and the hunted can wear the same badge. Give an immune cell a receptor that recognizes that badge, and it may attack its neighbors in the treatment batch. Cancer research has a grimly domestic name for this: fratricide.
March Biosciences, a Houston biotech, is testing a way around that problem. Its lead candidate, MB-105, targets CD5, a protein found on both malignant and normal T cells. The company’s wager is that a carefully chosen receptor design can make a difficult target usable without adding another gene-editing operation.
- The medicine: patients’ own T cells, engineered to recognize CD5.
- The distinction: target downregulation without extra gene editing.
- The test: Phase 2 lymphoma data, still early and still small.
The target that turns on its own
CAR-T treatment gives T cells a chimeric antigen receptor, or CAR, that helps them recognize a cancer target. March’s version has a useful additional behavior. As CEO Sarah Hein explained in a May 2026 interview, the CAR binds CD5 on the therapeutic cell itself, prompting that protein’s internalization and degradation. The cell becomes functionally CD5-negative at the protein level.
“The CAR T cells become functionally CD5-negative at the protein level.”
Sarah Hein / May 2026 interview
That distinction matters. MB-105 cells are genetically engineered to express their CAR. March avoids additional gene editing to remove CD5. Describing the treatment as genetically unmodified would miss the machinery that makes it work.
An academic result needs a company
March was founded in 2021 by Hein and the scientists Maksim Mamonkin and Malcolm Brenner. The program emerged from the Center for Cell and Gene Therapy, involving Baylor College of Medicine, Houston Methodist Hospital and Texas Children’s Hospital. Hein encountered Mamonkin through the Texas Medical Center’s cancer therapeutics accelerator.
The clinical evidence interested her; the development setting imposed a ceiling. The product, she told Pulse 2.0, had “reached the limits of academic development.” That is a recognizable predicament in biotechnology. A research institution can produce a promising treatment without possessing all the capital, production systems and commercial machinery needed to develop it at scale.
Sarah Hein
Maksim Mamonkin
Malcolm BrennerThe beneficiaries are patients whose T-cell lymphoma has returned or resisted treatment. Today, access to MB-105 runs through clinical trials and specialist centers. March is a therapeutic developer pursuing potential commercialization; its lead medicine is investigational. Baylor’s 2024 ventures report describes an equity stake in March, plus development milestones and royalties.
The factory belongs in the pitch
An autologous therapy starts with the patient’s own cells. Collect them, engineer them, expand them, then return them. Each batch begins with a different immune system, shaped by disease and previous treatments. A persuasive laboratory result must survive that variation.
March made production expertise part of its development plan. In September 2023, it allied with CTMC, the MD Anderson Cancer Center and Resilience joint venture. In October 2024, it announced a partnership with Volnay Therapeutics for technical oversight and scalable manufacturing. These relationships put specialist capability beside the clinical program.
That October also brought a $28.4 million Series A, co-led by Mission BioCapital and 4BIO Capital. The announced uses included Phase 2 development, optimized manufacturing and further pipeline work. March reported more than $51 million raised across equity and non-dilutive sources at that point.
Financing for development. A funding round does not reveal what a finished dose will cost.
Support has also come from public and manufacturing grants: approximately $13.4 million from CPRIT in 2023 and a $200,000 G-Rex grant announced in April 2025. CPRIT’s May 2026 approvals include a further $1,993,978 award for advancing MB-105. These numbers describe financing commitments, rather than a tally of money spent.
Five responses, with the denominator attached
March announced its first Phase 2 patient dosing in April 2025. In December, at the American Society of Hematology meeting, it reported a complete response in all five evaluable patients in the primary efficacy cohort. Those patients came from a six-patient safety run-in; the primary cohort required at least 50% CD5 expression.
Complete responses in the evaluable primary cohort. Six patients in the safety run-in. Small, uncontrolled, preliminary.
The patients had received between two and eight previous systemic treatment regimens. That makes the signal worth following. Five responses cannot establish a dependable response rate across a larger population, long-term cure or superiority to another treatment. The independent monitoring committee allowed the study to advance to its second stage.
The trial registry lists estimated enrollment of 46. It is an open-label, single-arm study: investigators and patients know the treatment, and there is no randomized comparison group. FDA orphan drug and RMAT designations support development. Neither designation makes MB-105 an approved medicine.
A useful choice, with biological limits
March sits within a broader effort to bring cell therapy to T-cell malignancies. Wugen’s adjacent WU-CART-007 program uses healthy donor cells, targets CD7 and employs gene editing. Its T-ALL and lymphoblastic lymphoma studies involve different diseases and designs; response percentages cannot be ranked like competing restaurant reviews.
March’s approach still depends on the tumor presenting the target. Patient-cell variability remains. Depleting normal T cells can complicate immune recovery, and infection is a serious consideration. Hein has described clinicians monitoring recovery or considering stem-cell transplantation. The biology does not stop being complicated after a response.
For founders, the transferable lesson is a practical one: identify the production risk while the science is promising, then bring in people who know how to manage it. For patients and clinicians, March’s trial information offers a route to an eligibility discussion. The next persuasive chapter will require more patients and longer follow-up.