Phase Ib dose-escalation trial of taselisib (GDC-0032) in combination with HER2-directed therapies in patients with advanced HER2+ breast cancer.

BACKGROUND: In most patients with advanced human epidermal growth factor receptor-2-positive (HER2+) breast cancer, anti-HER2 therapies fail due to the development of acquired resistance, potentially mediated through phosphoinositide-3-kinase (PI3K) signaling. We investigated adding taselisib, an α-selective potent oral inhibitor of PI3K, to different HER2-directed regimens in order to improve disease control. PATIENTS AND METHODS: Patients (n = 68) with advanced HER2+ breast cancer were enrolled to this open-label, dose-escalation phase Ib study. The primary endpoint was defining the maximal tolerated dose (MTD) for the various taselisib-containing combinations. The secondary endpoint was safety. Exploratory endpoints included circulating tumor DNA analysis. The study included four cohorts: (A) taselisib + trastuzumab emtansine (T-DM1), (C) taselisib + trastuzumab and pertuzumab (TP), (D) taselisib + TP + paclitaxel, and (E) taselisib + TP + fulvestrant. RESULTS: Following dose escalation, the taselisib MTD was defined as 4 mg once daily. Treatment was associated with significant toxicities, as 34 out of 68 patients experienced grade ≥3 adverse events (AEs) attributed to taselisib, the most common all-grade AEs being diarrhea, fatigue, and oral mucositis. At a median follow-up of 43.8 months, median progression-free survival (PFS) for the MTD-treated population in cohorts A, C, and E was 6.3 [95% confidence interval (CI) 3.2-not applicable (NA)] months, 1.7 (95% CI 1.4-NA) months, and 10.6 (95% CI 8.3-NA) months, respectively. The median PFS for patients in cohort A with prior T-DM1 use was 10.4 (95% CI 2.7-NA) months. CONCLUSIONS: PIK3CA targeting with taselisib in combination with HER2-targeted therapies was associated with both promising efficacy and substantial toxicities.

Circulating tumor DNA association with residual cancer burden after neoadjuvant chemotherapy in triple-negative breast cancer in TBCRC 030.

BACKGROUND: We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy. PATIENTS AND METHODS: We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence. RESULTS: Of 139 patients, 68 had complete samples and no additional neoadjuvant chemotherapy. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000 variants) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3 and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10-4 (range 7.9 × 10-7-4.9 × 10-1). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10 of 11 patients with RCB 0, 3 of 8 with RCB 1, 4 of 15 with RCB 2 and 0 of 4 with RCB 3. Among six patients with known recurrence, five had persistent ctDNA at week 12. CONCLUSIONS: Neoadjuvant chemotherapy for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine whether ctDNA-guided approaches can improve outcomes.

TBCRC 030: a phase II study of preoperative cisplatin versus paclitaxel in triple-negative breast cancer: evaluating the homologous recombination deficiency (HRD) biomarker.

BACKGROUND: Cisplatin and paclitaxel are active in triple-negative breast cancer (TNBC). Despite different mechanisms of action, effective predictive biomarkers to preferentially inform drug selection have not been identified. The homologous recombination deficiency (HRD) assay (Myriad Genetics, Inc.) detects impaired double-strand DNA break repair and may identify patients with BRCA1/2-proficient tumors that are sensitive to DNA-targeting therapy. The primary objective of TBCRC 030 was to detect an association of HRD with pathologic response [residual cancer burden (RCB)-0/1] to single-agent cisplatin or paclitaxel. PATIENTS AND METHODS: This prospective phase II study enrolled patients with germline BRCA1/2 wild-type/unknown stage I-III TNBC in a 12-week randomized study of preoperative cisplatin or paclitaxel. The HRD assay was carried out on baseline tissue; positive HRD was defined as a score ≥33. Crossover to an alternative chemotherapy was offered if there was inadequate response. RESULTS: One hundred and thirty-nine patients were evaluable for response, including 88 (63.3%) who had surgery at 12 weeks and 51 (36.7%) who crossed over to an alternative provider-selected preoperative chemotherapy regimen due to inadequate clinical response. HRD results were available for 104 tumors (74.8%) and 74 (71.1%) were HRD positive. The RCB-0/1 rate was 26.4% with cisplatin and 22.3% with paclitaxel. No significant association was observed between HRD score and RCB response to either cisplatin [odds ratio (OR) for RCB-0/1 if HRD positive 2.22 (95% CI: 0.39-23.68)] or paclitaxel [OR for RCB-0/1 if HRD positive 0.90 (95% CI: 0.19-4.95)]. There was no evidence of an interaction between HRD and pathologic response to chemotherapy. CONCLUSIONS: In this prospective preoperative trial in TNBC, HRD was not predictive of pathologic response. Tumors were similarly responsive to preoperative paclitaxel or cisplatin chemotherapy.

A phase II feasibility study of palbociclib in combination with adjuvant endocrine therapy for hormone receptor-positive invasive breast carcinoma.

BACKGROUND: The CDK4/6 inhibitor palbociclib prolongs progression-free survival in hormone receptor-positive/HER2-negative (HR+/HER2-) metastatic breast cancer when combined with endocrine therapy. This phase II trial was designed to determine the feasibility of adjuvant palbociclib and endocrine therapy for early breast cancer. PATIENTS AND METHODS: Eligible patients with HR+/HER2- stage II-III breast cancer received 2 years of palbociclib at 125 mg daily, 3 weeks on/1 week off, with endocrine therapy. The primary end point was discontinuation from palbociclib due to toxicity, non-adherence, or events related to tolerability. A discontinuation rate of 48% or higher would indicate the treatment duration of 2 years was not feasible, and was evaluated under a binomial test using a one-sided α = 0.025. RESULTS: Overall, 162 patients initiated palbociclib; over half had stage III disease (52%) and most received prior chemotherapy (80%). A total of 102 patients (63%) completed 2 years of palbociclib; 50 patients discontinued early for protocol-related reasons (31%, 95% CI 24% to 39%, P = 0.001), and 10 discontinued due to protocol-unrelated reasons. The cumulative incidence of protocol-related discontinuation was 21% (95% CI 14% to 27%) at 12 months from start of treatment. Rates of palbociclib-related toxicity were congruent with the metastatic experience, and there were no cases of febrile neutropenia. Ninety-one patients (56%) required at least one dose reduction. CONCLUSION: Adjuvant palbociclib is feasible in early breast cancer, with a high proportion of patients able to complete 2 years of therapy. The safety profile in the adjuvant setting mirrors that observed in metastatic disease, with approximately half of the patients requiring dose-modification. As extended duration adjuvant palbociclib appears feasible and tolerable for most patients, randomized phase III trials are evaluating clinical benefit in this population. CLINICALTRIALS.GOV REGISTRATION: NCT02040857.

A phase II study of bevacizumab in combination with vinorelbine and trastuzumab in HER2-positive metastatic breast cancer.

We aimed to evaluate the efficacy and feasibility of combining trastuzumab/vinorelbine with bevacizumab in patients with first-or second-line HER2-positive, metastatic breast cancer (MBC). Eligible patients had HER2-positive measureable MBC, with no more than one prior line of chemotherapy, and were treated with trastuzumab (4 mg/kg × 2 mg/kg weekly thereafter), vinorelbine (25 mg/m(2) weekly), and bevacizumab (10 mg/kg every 2 weeks). Co-primary endpoints were (a) the proportion of patients alive and progression-free at 1 year and (b) safety profile/feasibility. Feasibility was defined as a rate of grade 3/4 non-hematologic toxicity attributable to protocol-based therapy <20 %. Twenty-nine patients were enrolled (n = 22 first-line, n = 7 second-line). Median age was 48 years (range 37-68). The median number of cycles received was 8 (1-23) and median duration on treatment was 7.4 months (range 1-22). The study was closed early due to higher-than-expected rates of grade 3/4 non-hematologic toxicities, with 50 events in 20 patients. A total of six patients (21 %) were taken off study for treatment-related toxicity. Most common treatment-related toxicities included fatigue (n = 7), febrile neutropenia (n = 4), and headache (n = 3). At 1 year, 8/22 first-line (36 %) and 2/7 second-line (29 %) patients were alive and progression-free. Median PFS was 9.9 months and 7.8 months in the first- and second-line cohorts, respectively. Objective responses were observed in 16/22 (73 %) and 5/7 (71 %) patients in the first- and second-line settings. Although the combination of vinorelbine, trastuzumab, and bevacizumab showed notable activity in HER2-positive MBC, the proportion of first-line patients alive and progression-free at 1 year was deemed unlikely to reach the pre-defined threshold for declaring success. Additionally, unacceptable toxicity was observed, at rates greater than previously reported with vinorelbine/trastuzumab or vinorelbine/bevacizumab doublet combinations.

SABRE-B: an evaluation of paclitaxel and bevacizumab with or without sunitinib as first-line treatment of metastatic breast cancer.

BACKGROUND: The vascular endothelial growth factor (VEGF) pathway can be targeted through VEGF neutralization or VEGF receptor (VEGFR) blockade using tyrosine kinase inhibition. Because laboratory models suggest that combining these approaches might be synergistic, we sought to evaluate the feasibility and efficacy of combining sunitinib with paclitaxel + bevacizumab (PB). METHODS: Patients with human epidermal growth factor receptor 2 (HER2)-negative, metastatic breast cancer receiving first-line chemotherapy were randomized to PB or PB with sunitinib (PBS), with planned escalation of the sunitinib dose. RESULTS: Forty-six patients were randomized to PB or PBS with sunitinib dosed at 25 mg p.o. daily. Patients receiving PBS encountered substantial toxicity that precluded adequate treatment. The percentage of patients with grade ≥3 adverse events was greater in the PBS arm than the PB arm (83% versus 57%), and sunitinib dosing was modified in 78% of patients, most often due to neutropenia, febrile neutropenia, and fatigue. In addition, 44% of patients had sunitinib dose reduction to 12.5 mg, and 39% required discontinuation. Patients receiving PBS had more bevacizumab treatment interruptions and discontinuations because of toxicity. Median treatment duration was longer in the PB arm compared with the PBS arm (14.1 versus 11.1 weeks), reflecting early treatment discontinuation of PBS. Because of poor tolerability of the addition of sunitinib to PB, the planned sunitinib dose escalation was halted and the study accrual was terminated. CONCLUSION: Adding sunitinib to standard doses of bevacizumab plus paclitaxel for metastatic breast cancer is not feasible. Different strategies will be required to evaluate whether there is additional clinical benefit to combining VEGF/VEGFR-targeted agents.

Tolerability of and adherence to combination oral therapy with gefitinib and capecitabine in metastatic breast cancer.

PURPOSE: This phase I study explored gefitinib (G) and capecitabine (C) in metastatic breast cancer (MBC). METHODS: Sequential cohorts (n = 3) received G and escalating C on a 14 day on/7 day off schedule, with a validation cohort (n = 10) at the maximum tolerated dose (MTD). Dose limiting toxicity (DLT) was defined in cycle 1. The primary endpoint was safety; secondary endpoints included response and adherence. RESULTS: About 19 patients were treated for a median of 5 cycles. No patients in sequential cohorts experienced DLT; C MTD was 2,000 mg/m(2)/day when paired with daily G 250 mg. In the validation cohort, four experienced serious toxicities, including diarrhea, mucositis, and palmarplantar dysesthesia. At the MTD, 6 (46%) required a C dose reduction, and 3 (23%) came off study for toxicity. One partial response was observed (8%, 95% CI 0.2-38.5%); five had stable disease >24 weeks (26, 95% CI 9-51%). Patients missed few drug doses, with the suggestion of overadherence to therapy. CONCLUSIONS: In this phase I study of G and C in MBC, a C MTD was identified, and significant toxicity was observed. About 8% demonstrated a response, with 26% maintaining stable disease. The possibility of overadherence, as suggested in this study, may have implications for other trials of oral antineoplastic therapy.

On "Telepathic dreams?": an unpublished paper by Robert J. Stoller.

In 1973 Robert Stoller wrote a paper on a series of dreams-his own and his patients'--that he reluctantly found himself calling "telepathic." He never submitted the paper for publication, though he returned to the topic of unconscious communication and telepathy with increasing fascination in the years before his death. Publication of Stoller's paper seems particularly opportune just now. In it he pleads for open-minded examination of data, however alien to current scientific belief those data seem. In the past, despite numerous published reports of possibly telepathic experiences in analysis, their investigation remained relatively one-sided, since a technical posture of anonymity with patients constrained analysts from revealing that a communication struck them as telepathic. This has limited what analysts have been able to learn about the information actually exchanged, how it was exchanged, and whether the communication was experienced as uncanny by the patient. Recent attention to the intersubjective nature of the analytic situation has led to a deemphasis of anonymity, opening freer dialogue that may facilitate the rigorous investigation Stoller calls for. Such investigation may further analytic understanding of unconscious mental function and communication in the clinical setting, and lend perspective to the growing body of carefully controlled experimental research on anomalous mental phenomena.

Hyperhomocysteinemia confers an independent increased risk of atherosclerosis in end-stage renal disease and is closely linked to plasma folate and pyridoxine concentrations.

BACKGROUND: A high level of total plasma homocysteine is a risk factor for atherosclerosis, which is an important cause of death in renal failure. We evaluated the role of this as a risk factor for vascular complications of end-stage renal disease. METHODS AND RESULTS: Total fasting plasma homocysteine and other risk factors were documented in 176 dialysis patients (97 men, 79 women; mean age, 56.3 +/- 14.8 years). Folate, vitamin B12, and pyridoxal phosphate concentrations were also determined. The prevalence of high total homocysteine values was determined by comparison with a normal reference population, and the risk of associated vascular complications was estimated by multiple logistic regression. Total homocysteine concentration was higher in patients than in the normal population (26.6 +/- 1.5 versus 10.1 +/- 1.7 mumol/L; P < .01). Abnormally high concentrations (> 95th percentile for control subjects, 16.3 mumol/L) were seen in 149 patients (85%) with end-stage renal disease (P < .001). Patients with a homocysteine concentration in the upper two quintiles (> 27.8 mumol/L) had an independent odds ratio of 2.9 (CI, 1.4 to 5.8; P = .007) of vascular complications. B vitamin levels were lower in patients with vascular complications than in those without. Vitamin B6 deficiency was more frequent in patients than in the normal reference population (18% versus 2%; P < .01). CONCLUSIONS: A high total plasma homocysteine concentration is an independent risk factor for atherosclerotic complications of end-stage renal disease. Such patients may benefit from higher doses of B vitamins than those currently recommended.

Purification and characterization of the vaccinia virus deoxyuridine triphosphatase expressed in Escherichia coli.

The deoxyuridine triphosphatase gene of vaccinia virus, encoded by the open reading frame F2L, was cloned into Escherichia coli and expressed under the control of a bacteriophage T7 promoter. After induction of T7 RNA polymerase by isopropyl beta-D-thiogalactopyranoside, a 16.5-kDa peptide accumulated to high levels. This 16.5-kDa protein was purified to homogeneity and characterized. Gel filtration of the purified protein revealed a trimeric native structure. Biochemical analysis revealed the enzyme to be a metalloenzyme; enzymatic activity is inhibited by EDTA. This inhibition was reversed by the addition of Mg2+, Mn2+, or Zn2+. While the enzyme activity was highly specific for dUTP with an apparent Km of 0.94 microM, inhibition studies show that 8-azido-ATP acted as a competitive inhibitor of dUTP with a Ki of approximately 173 microM. Also, protection studies demonstrated that nucleotide competitors inhibit photoincorporation of the photoaffinity analogues [gamma-32P]5-azido-dUTP and [gamma-32P]8-azido-ATP. This suggests that while catalytic activity is limited to dUTP, other nucleotides can bind the active site.

Subjectivity and intersubjectivity of clinical facts.

The author has learned a great deal from the IJPA 75th Anniversary Issue, particularly regarding ways in which psychoanalysts across the world are consensually re-defining psychoanalysis as a quintessentially subjective and intersubjective endeavour. In summarising her response to the Issue, she addresses the ways in which its focus on psychoanalytic subjectivity and intersubjectivity helps to define the nature of psychoanalysis as a scientific endeavour. In addition, she identifies an area that she wished had been more developed in the Issue: some further specification of the cognitive and communicative processes that make for psychoanalytic subjectivity and intersubjectivity. She speculates that, as we continue our attempts further to understand those processes, we may find it valuable to look towards a body of research that is absent from consideration in the 75th Anniversary Issue (and is, for that matter, absent from serious and scientific consideration by psychoanalysts in general): research on mental effects currently considered 'anomalous', or outside the bounds of conventionally defined human mental function and capacity. She describes briefly some of that research in the context of its possible relevance to issues of psychoanalytic subjectivity and intersubjectivity. She takes up the specific relevance of that research to phenomena we have traditionally subsumed under categories of experience like intuition, empathic attunement and unconscious communication.

Homocysteine and coronary atherosclerosis.

Homocysteine is increasingly recognized as a risk factor for coronary artery disease. An understanding of its metabolism and of the importance of vitamins B6 and B12 and folate as well as enzyme levels in its regulation will aid the development of therapeutic strategies that, by lowering circulating concentrations, may also lower risk. Possible mechanisms by which elevated homocysteine levels lead to the development and progression of vascular disease include effects on platelets, clotting factors and endothelium. This review presents the clinical and basic scientific evidence supporting the risk and mechanisms of vascular disease associated with elevated homocysteine concentrations as well as the results of preliminary therapeutic trials.

Hyperhomocysteinemia and low pyridoxal phosphate. Common and independent reversible risk factors for coronary artery disease.

BACKGROUND: High plasma homocysteine is associated with premature coronary artery disease in men, but the threshold concentration defining this risk and its importance in women and the elderly are unknown. Furthermore, although low B vitamin status increases homocysteine, the link between these vitamins and coronary disease is unclear. METHODS AND RESULTS: We compared 304 patients with coronary disease with 231 control subjects. Risk factors and concentrations of plasma homocysteine, folate, vitamin B12, and pyridoxal 5'-phosphate were documented. A homocysteine concentration of 14 mumol/L conferred an odds ratio of coronary disease of 4.8 (P < .001), and 5-mumol/L increments across the range of homocysteine conferred an odds ratio of 2.4 (P < .001). Odds ratios of 3.5 in women and of 2.9 in those 65 years or older were seen (P < .05). Homocysteine correlated negatively with all vitamins. Low pyridoxal 5'-phosphate (< 20 nmol/L) was seen in 10% of patients but in only 2% of control subjects (P < .01), yielding an odds ratio of coronary disease adjusted for all risk factors, including high homocysteine, of 4.3 (P < .05). CONCLUSIONS: Within the range currently considered to be normal, the risk for coronary disease rises with increasing plasma homocysteine regardless of age and sex, with no threshold effect. In addition to a link with homocysteine, low pyridoxal-5'-phosphate confers an independent risk for coronary artery disease.

Absence of blood formation in mice lacking the T-cell leukaemia oncoprotein tal-1/SCL.

Chromosomal translocations associated with malignancies often result in deregulated expression of genes encoding transcription factors. In human T-cell leukaemias such regulators belong to diverse protein families and may normally be expressed widely (for example, Ttg-1/rbtn1, Ttg-2/rbtn2), exclusively outside the haematopoietic system (for example, Hox11), or specifically in haematopoietic cells and other selected sites (for example, tal-1/SCL, lyl-1). Aberrant expression within T cells is though to interfere with programmes of normal maturation. The most frequently activated gene in acute T-cell leukaemias, tal-1 (also called SCL), encodes a candidate regulator of haematopoietic development, a basic-helix-loop-helix protein, related to critical myogenic and neurogenic factors. Here we show by targeted gene disruption in mice that tal-1 is essential for embryonic blood formation in vivo. With respect to embryonic erythropoiesis, tal-1 deficiency resembles loss of the erythroid transcription factor GATA-1 or the LIM protein rbtn2. Profound reduction in myeloid cells cultured in vivo from tal-1 null yolk sacs suggests a broader defect manifest at the myelo-erythroid or multipotential progenitor cell level.

The phallic castration complex and primary femininity: paired developmental lines toward female gender identity.

I suggest that two developmental lines contribute to the achievement of female gender identity. One is rooted in the phallic castration complex, and the other in primary femininity. Far from being mutually exclusive, the two comprise necessary aspects of every girl's progress toward becoming a woman. To that extent, every woman's analysis will include the analysis of compromise formations that emerge from both. In distinguishing clinical manifestations of each developmental line, I suggest that it may be useful to conceptualize primary femininity and the phallic castration complex as affect-defense configurations which incorporate two fundamentally different ideas about danger. In conflicts of primary femininity, danger is anticipated: anxiety is the signal for compromise formation, since what is actually possessed (the female genital) is valued and is therefore imagined as subject to danger. In the phallic castration complex, danger is imagined already to have occurred. Depressive affect becomes the primary motive for defense, based on a fantasy that what is valued (the male genital) has already been lost. This distinction may facilitate our efforts to specify exactly how recent revisions in theories of female development have explicit implications for practice.

Some implications for psychoanalytic technique drawn from analysis of a dying patient.

The analysis of a dying patient is presented. The suggestion is made that analytic work with people who are dying is both possible and productive. The unusual elements that are introduced by such cases are examined in terms of how they highlight problems in our theory of technique. Particularly, the analyst's empathy and compassion are emphasized as crucial: not because of how they affect the patient but because of how they affect the analyst and the analyst's ability to analyze.

When theory and practice diverge: gender-related patterns of referral to psychoanalysts.

This study tests the hypothesis that female analysts, relative to male analysts, receive a disproportionately small percentage of male referrals. Referral patterns for 170 analysts from four institutes accredited by the American Psychoanalytic Association were examined. One thousand, five hundred and ten patients referrals were studied. The findings were extremely robust and offered dramatic confirmation of our hypothesis. The major implications of the study are as follows: (1) Women analysts receive relatively few adult male referrals, making it difficult for them to gain requisite clinical experience with men. (2) Analysts and nonanalysts alike demonstrate a reluctance to refer male patients to female analysts. (3) Adult referrals, including those made by analysts, are significantly influenced by the issue of gender match between patient and analyst. (4) Analysts' behavior with regard to making referrals does not correspond to explicit clinical theory regarding how analysts make referrals--specifically, the extent to which gender influences the referral process is not adequately described by theory. We believe that these findings are of some concern from the standpoint of analytic education and that they also raise questions regarding unacknowledged aspects of how gender match between patient and analyst enters into clinical decision making.(ABSTRACT TRUNCATED AT 250 WORDS)

Transport of membrane-bound macromolecules by M cells in follicle-associated epithelium of rabbit Peyer's patch.

M cells in Peyer's patch epithelium conduct transepithelial transport of luminal antigens to cells of the mucosal immune system. To determine the distribution of specific lectin-binding sites on luminal membranes of living M cells and to follow the transport route of membrane-bound molecules, lectin-ferritin conjugates and cationized ferritin were applied to rabbit Peyer's patch mucosa in vivo and in vitro. The degree to which binding enhances transport was estimated by comparing quantitatively the transport of an adherent probe, wheat germ agglutinin-ferritin, to that of a nonadherent BSA-colloidal gold probe. When applied to fixed tissue, the lectins tested bound equally well to M cells and columnar absorptive cells. On living mucosa, however, ferritin conjugates of wheat germ agglutinin and Ricinus communis agglutinins I and II bound more avidly to M cells. Absorptive cells conducted little uptake and no detectable transepithelial transport. Lectins on M cell membranes were endocytosed from coated pits, rapidly transported in a complex system of tubulocisternae and vesicles, and remained adherent to M cell basolateral membranes. Cationized ferritin adhered to anionic sites and was similarly transported, but was released as free clusters at M cell basolateral surfaces. When applied simultaneously to Peyer's patch mucosa, wheat germ agglutinin-ferritin was transported about 50 times more efficiently than was bovine serum albumin-colloidal gold.