A new class of oral drugs, BCL6 degraders, are demonstrating complete remissions as a single agent in heavily pretreated aggressive lymphoma patients. This activity was surprising, as they were initially expected to require combination therapy to be effective, signaling a promising new non-cell surface targeting mechanism.
Combining polatuzumab vedotin with bispecific antibodies appears particularly effective for patients with double-hit lymphoma. This is significant because these high-risk patients, who have poor prognoses, were notably excluded from pivotal trials like STAR GLOW, suggesting a potential new standard for this specific subgroup.
BTK degraders work despite most kinase inhibitor resistance mutations. However, resistance to degraders themselves alters the BTK binding pocket so significantly that subsequent targeting with any BTK kinase inhibitor is unlikely to be effective, positioning them as a potential end-of-line therapy.
The drug exhibits a multimodal mechanism. It not only reverses chemoresistance and halts tumor growth but also 'turns cold tumors hot' by forcing cancer cells to display markers that make them visible to the immune system. This dual action of direct attack and immune activation creates a powerful synergistic effect.
Unlike some targeted therapies that lead to antigen loss, treatment with the CD19-directed antibody tafasitamab does not appear to eliminate CD19 expression on lymphoma cells. This is a critical finding, as it preserves the target for subsequent potent therapies like CD19-directed CAR T-cells.
Pathways like integrins have long been of interest but lacked effective therapeutic approaches. The advent of new technologies, such as antibody-drug conjugates and checkpoint inhibitors, has created opportunities to re-explore these older targets with potent, modern drugs, breathing new life into decades-old research.
BTK inhibitors like ibrutinib can improve T-cell function. When combined with liso-cel CAR-T, this synergistic effect dramatically improves outcomes in heavily pretreated patients, increasing the complete response rate from 20% to 45% and the overall response rate from 48% to 86%.
Despite strong single-agent trial results, experts believe the field is shifting away from continuous monotherapy. The most significant future impact for pirtobrutinib will likely be as a backbone of fixed-duration combination therapies with drugs like venetoclax, aiming for deeper remissions without indefinite treatment.
Unlike older antibody-drug conjugates (ADCs), newer agents are designed so their chemotherapy payload can diffuse out of the target cell and kill nearby tumor cells that may not even express the target antigen. This "bystander effect" significantly enhances their anti-tumor activity.
Long-term follow-up from the pivotal epcoritamab trial reveals that 46% of DLBCL patients who achieve a complete remission maintain it at four years. This durability provides strong evidence that bispecific monotherapy, not just CAR-T, can be a curative treatment for a subset of patients.
The ECHELON-3 trial showed that brentuximab vedotin plus R-squared is effective in relapsed/refractory DLBCL, even in patients with negligible CD30 expression. This suggests the drug's benefit may stem from immune synergy or other mechanisms, not just direct CD30 targeting.